behavior

JoVE Behavior documents observational and experimental techniques that seek to understand human and animal behavior. Work in this field includes analysis of genetic causes and physiological responses to internal or external stimuli as well as the implicated brain regions.

Sciences du comportement

biochemistry

JoVE Biochemistry publishes experiments that investigate the structure, function, and interactions of biological molecules. The video articles in this section demonstrate methods to study nucleic acids, proteins, carbohydrates and lipids as well as enzyme function, protein folding, molecular interactions and biochemical reactions.

Biochimie

bioengineering

JoVE Bioengineering merges both physical and life sciences to understand and predict biological processes. Applying physical science tools to life science questions allow for the discovery of better technologies to measure, diagnose, and clinically treat disease.

Bio-ingénierie

biology

JoVE Biology welcomes all general biology research methodologies. Content in this section canvases all fields of cell, molecular, and organismal biology, ranging from new applications of standard techniques to novel approaches aimed at understanding the functions of life and living organisms. This diverse section includes, but is not limited to, techniques in physical biology, cellular biochemistry, genetics, physiology, systems biology and a combination of eukaryotic and prokaryotic model systems.

Biologie

cancer research

JoVE Cancer Research illustrates experimental approaches in biomedical research and clinical practice aimed at understanding, detecting, treating and preventing cancer. The video articles in this section demonstrate methods to study the cellular and molecular mechanisms of cancer, animal models of cancer research, development of new therapies and diagnostics, tumor imaging, chemical and radiation treatments, surgical procedures and improvements in therapy. These video articles offer researchers and clinical practitioners an efficient way to learn the technologies and experimental methods in cancer research.

Recherche en cancérologie

chemistry

JoVE Chemistry surveys a broad scope of chemical disciplines. This collection includes fundamental and applied research that investigates molecular interactions, properties, and structure spanning in the following core divisions: analytical, organic, organometallic, inorganic, bioinorganic, and biochemistry. This section also includes the design and preparation of materials and small molecules for advanced or unique applications.

Chimie

developmental biology

JoVE Developmental Biology publishes research methodologies in the field of developmental biology. This includes methods that are used to study biological development in vitro and in vivo at the molecular, cellular, tissue, organ and whole organism levels.

Biologie du développement

engineering

JoVE Engineering encompasses a broad range of experimental and instrumental techniques utilized in physics research. Investigations in this area strive to address and answer a broad range of scientific questions, such as device mechanisms and efficiencies, using physical tools. This approach often requires a combination of specialties, and research in this area tends to be interdisciplinary with contributions from mechanical, electrical, and chemical engineers.

Ingénierie

environment

JoVE Environment is dedicated to research methodologies that address environmental concerns and seek to better understand Earth's ecosystem.  Special consideration is given to experimental methodologies that assess society’s impact on the environment, suggest solutions for protecting Earth’s resources, and develop sustainable fuel sources. Moving towards an environmentally conscious planet is a collaborative effort with contributions from both life and physical scientists.

Environnement

genetics

JoVE Genetics publishes video articles demonstrating experimental approaches to investigate gene function and regulation. This includes methods to study gene expression, mutagenesis, epigenetics, genetic determinants of development, genetic disorders, population genetics and evolution.

Génétique

immunology and infection

JoVE Immunology and Infection includes content from a variety of fields working toward a shared initiative of improving global health. Techniques evaluating the biological response to pathogens from the molecular to organismal level are presented as well as therapeutic agents and their efficacy in treating disease.

Immunologie et infection

medicine

JoVE Medicine serves as a connection between basic research and clinical applications. Articles may present medical procedures, case studies or clinical trial methodologies. Included studies are often modeled towards predictive, preventative, personalized, and practical approaches to treatment of disease. The goal of research methodologies in this section is to improve overall patient care and prognosis.

Médecine

neuroscience

JoVE Neuroscience is a multidisciplinary section devoted to investigations of the structure, function, physiology, and pathophysiology of the brain and nervous system. Included methodologies range from molecular and cellular level studies to full central and peripheral neural systems. Potential treatment platforms and surgical techniques for neurological diseases and disorders are also presented in this section.

Neurosciences

jove journal

JoVE Journal

Journal vidéo scientifique. Evaluation par les pairs. Multi-disciplinaire. Indexé dans Pubmed et Web of Science.

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Research

Experimental Protocol for Manipulating Plant-induced Soil Heterogeneity

Coexistence theory has often treated environmental heterogeneity as being independent of the community composition; however biotic feedbacks such as plant-soil feedbacks (PSF) have large effects on plant performance, and create environmental heterogeneity that depends on the community composition. Understanding the importance of PSF for plant community assembly necessitates understanding of the role of heterogeneity in PSF, in addition to mean PSF effects. Here, we describe a protocol for manipulating plant-induced soil heterogeneity. Two example experiments are presented: (1) a field experiment with a 6-patch grid of soils to measure plant population responses and (2) a greenhouse experiment with 2-patch soils to measure individual plant responses. Soils can be collected from the zone of root influence (soils from the rhizosphere and directly adjacent to the rhizosphere) of plants in the field from conspecific and heterospecific plant species. Replicate collections are used to avoid pseudoreplicating soil samples. These soils are then placed into separate patches for heterogeneous treatments or mixed for a homogenized treatment. Care should be taken to ensure that heterogeneous and homogenized treatments experience the same degree of soil disturbance. Plants can then be placed in these soil treatments to determine the effect of plant-induced soil heterogeneity on plant performance. We demonstrate that plant-induced heterogeneity results in different outcomes than predicted by traditional coexistence models, perhaps because of the dynamic nature of these feedbacks. Theory that incorporates environmental heterogeneity influenced by the assembling community and additional empirical work is needed to determine when heterogeneity intrinsic to the assembling community will result in different assembly outcomes compared with heterogeneity extrinsic to the community composition.

Understanding the role of environmental heterogeneity in species coexistence has typically focused on types of heterogeneity that are extrinsic to the community&#8217;s species composition. We provide novel detailed methods for creating soil heterogeneity treatments using soils subject to plant-soil feedback conditioning, or heterogeneity intrinsic to the community composition.

Protocole expérimental pour l&#39;hétérogénéité du sol Manipulation des plantes induite

Coexistence theory has often treated environmental heterogeneity as being independent of the community composition; however biotic feedbacks such as ...

Studying Food Reward and Motivation in Humans

A key challenge in studying reward processing in humans is to go beyond subjective self-report measures and quantify different aspects of reward such as hedonics, motivation, and goal value in more objective ways. This is particularly relevant for the understanding of overeating and obesity as well as their potential treatments. In this paper are described a set of measures of food-related motivation using handgrip force as a motivational measure. These methods can be used to examine changes in food related motivation with metabolic (satiety) and pharmacological manipulations and can be used to evaluate interventions targeted at overeating and obesity. However to understand food-related decision making in the complex food environment it is essential to be able to ascertain the reward goal values that guide the decisions and behavioral choices that people make. These values are hidden but it is possible to ascertain them more objectively using metrics such as the willingness to pay and a method for this is described. Both these sets of methods provide quantitative measures of motivation and goal value that can be compared within and between individuals.

This article describes a set of methods for the measurement of food related motivation and food related goal values in humans.

Etudier récompense alimentaire et de la motivation chez les humains

A key challenge in studying reward processing in humans is to go beyond subjective self-report measures and quantify different aspects of reward such as ...

Psychosurgery

Psychosurgery, the surgical alteration or permanent removal of brain tissue to alleviate severe psychological conditions, stands as one of the most radical and controversial treatments in the history of mental health care. Its development and application have evolved significantly, marked by dramatic shifts in scientific understanding and ethical perspectives.
Historical Development of Psychosurgery
In the 1930s, Portuguese neurologist Antonio Egas Moniz introduced a surgical procedure designed to sever neural pathways between the frontal lobe and thalamus. This intervention aimed to mitigate severe mental health disorders, including schizophrenia and severe anxiety. Despite its crude methodology, the surgeries gained recognition, and Moniz was awarded the Nobel Prize in Physiology or Medicine in 1949.
Walter Freeman, an American neurologist, popularized and coined the term prefrontal lobotomy in the United States, introducing a simplified and faster technique that involved accessing the brain through the eye socket using a surgical instrument similar to an ice pick. Freeman performed over 3,000 lobotomies, often in public demonstrations, and fervently advocated for the procedure as a solution to various psychological disorders. However, his approach often overlooked long-term outcomes and ethical considerations.
Decline of Traditional Lobotomies
The widespread adoption of lobotomies from the 1930s to the 1960s resulted in significant and irreversible harm to many patients. Adverse effects included severe cognitive impairments, memory loss, emotional flatness, and personality changes. Coupled with the advent of psychiatric medications in the mid-1950s, which offered non-invasive alternatives, lobotomies fell out of favor. Reports of poor outcomes and heightened ethical scrutiny further discredited the procedure.
Modern Psychosurgical Techniques
Contemporary psychosurgery employs far more precise and controlled methods, targeting specific brain regions such as the amygdala or anterior cingulate cortex. Techniques like cingulotomy and capsulotomy are used to treat intractable psychiatric conditions such as severe obsessive-compulsive disorder (OCD) and major depressive disorder. These procedures are guided by advanced imaging technologies to minimize damage to surrounding tissues.
Stringent regulations, such as institutional review boards, now govern psychosurgery, ensuring thorough patient evaluation, informed consent, and surgeon&#39;s competency. These measures aim to balance the potential benefits of psychosurgery with its inherent risks, emphasizing its use as a last resort when all other treatments have failed.
Ethical and Scientific Considerations
Despite technological advances, psychosurgery remains a contentious field. Critics point to the procedure&#39;s historical misuse and potential for unintended consequences, while proponents argue for its value in treating otherwise untreatable conditions. Ongoing research seeks to refine surgical techniques and deepen understanding of the brain, underscoring the need for a cautious and ethical approach to this powerful intervention.

Psychosurgery involves removing or permanently destroying brain tissue to treat severe psychological conditions, making it a controversial biomedical ...

Couples Therapy

Couples therapy is a therapeutic approach designed to help individuals in intimate relationships address conflicts, improve communication, and foster healthier dynamics. It is appropriate for couples at various stages, including those who are dating, married, or in long-term partnerships, and aims to support partners in navigating their unique relational challenges.
Core Principles and Techniques
Couples therapy often incorporates cognitive-behavioral principles to identify and modify negative patterns within relationships. Therapists guide partners in understanding how their individual backgrounds, beliefs, past experiences, and behaviors influence their interactions. This insight is crucial in addressing issues such as poor communication, infidelity, jealousy, sexual difficulties, substance abuse, and the complexities of blended families or two-career households.
Therapists use various techniques such as validation, reframing, structural change, and detriangulation to promote relational growth. Validation involves acknowledging each partner&#39;s emotions and beliefs, as well as fostering mutual respect and understanding. Reframing helps couples view their challenges as shared problems rather than assigning blame, encouraging collaboration. The structural change focuses on reorganizing interaction patterns to create a supportive and functional environment, while detriangulation addresses external conflicts that may be diverting attention from the relationship itself.
Navigating High-Conflict Relationships
High-conflict relationships present unique challenges due to heightened emotions and volatility. Therapists act as mediators, helping partners navigate intense disagreements and work toward constructive resolutions. These situations require a nuanced approach to de-escalate tensions and facilitate productive dialogue.
Goals and Outcomes
The primary goal of couples therapy is to equip partners with tools to enhance understanding and foster healthier interactions. For some, this process strengthens the relationship, while for others, therapy may reveal irreconcilable differences, leading to a mutual decision to separate. Regardless of the outcome, therapy emphasizes clarity and informed decision-making, enabling couples to navigate their circumstances with greater insight and confidence.
By addressing relational dynamics and promoting constructive change, couples therapy supports partners in building more harmonious connections or reaching resolutions that align with their well-being.

Couples therapy helps individuals in intimate relationships resolve conflicts and improve dynamics. Couples may be dating, married, or in long-term ...

Interpersonal Psychotherapy

Interpersonal psychotherapy (IPT) is a structured, time-limited therapeutic approach initially developed to treat depression. It integrates key concepts from psychodynamic, humanistic, and cognitive-behavioral therapies, making it a uniquely eclectic framework. The therapy is rooted in the interpersonal theories of Adolph Meyer and Harry Stack Sullivan, as well as John Bowlby&#39;s attachment theory, and focuses on the interplay between interpersonal relationships and emotional well-being.
Foundations of Interpersonal Psychotherapy
The foundational premise of IPT is that interpersonal relationships significantly influence mood and psychological health. Sullivan emphasized the collaborative role of the therapist as a &#34;participant observer,&#34; working to identify and address maladaptive interpersonal patterns in the client&#39;s daily life. This focus on relationship dynamics distinguishes IPT from other therapeutic models. While it draws on psychodynamic concepts, IPT diverges from traditional psychodynamic therapy by explicitly emphasizing practical strategies to improve interpersonal functioning.
Structure and Scope of IPT
IPT is typically delivered in a short-term format, encompassing 12&#8211;16 sessions. The approach aims to enhance clients&#39; social skills, resolve interpersonal conflicts, and assist with life transitions, such as childbirth, retirement, or bereavement. The therapy is structured around specific problem areas identified during the initial assessment, such as role disputes, role transitions, unresolved grief, or interpersonal deficits. By addressing these areas, IPT helps clients develop healthier relationships and coping mechanisms.
Effectiveness Across Conditions
Originally designed to treat depression, IPT has demonstrated efficacy in combination with pharmacological treatments and as a standalone intervention. Clinical studies have shown its effectiveness in treating various conditions, including substance use disorders and eating disorders, with outcomes comparable to those achieved through cognitive-behavioral therapy. IPT&#39;s success lies in its ability to adapt its core principles to address the unique challenges associated with different mental health disorders.
The integration of theoretical insights with practical strategies makes IPT a versatile and evidence-supported approach, offering a collaborative pathway to improved interpersonal functioning and psychological health.

Interpersonal psychotherapy, or IPT, is an insight-based therapy focusing on the relationship between an individual&#39;s mood and their interpersonal ...

Community Based Intervention

Community-based interventions in mental health represent a paradigm shift from institution-centered care to treatments embedded within the fabric of local communities. By prioritizing inclusion and leveraging existing societal structures, this approach fosters a supportive environment conducive to addressing mental health challenges while promoting individual dignity and agency.
Foundations of Community Mental Health Programs
Central to the success of community-based interventions is the training of local stakeholders such as teachers, nurses, and community members. These individuals are equipped with fundamental counseling skills and are often involved in workshops aimed at stress management, substance abuse reduction, and interpersonal skill development. Such initiatives help extend mental health care beyond specialized professionals, making it more accessible and reducing stigma.
The deinstitutionalization movement of the 1960s marked the beginning of this transition. It was driven by concerns over the ethical failings of institutional care, which often subjected individuals to neglect and abuse, and by economic considerations regarding the unsustainable costs of long-term institutionalization. As individuals were reintegrated into communities, the focus shifted to creating support systems that address mental health in a holistic, culturally sensitive manner.
Empowerment and Sustainability
Community-based mental health programs emphasize empowerment, enabling individuals to actively engage in their recovery and integrate fully into familial and societal contexts. This approach, championed by community psychologists, seeks to cultivate long-term well-being by embedding care within the individual&#39;s social and cultural milieu.
However, these programs require robust support in terms of local resources and government funding. Sustainable initiatives are essential to ensure continuity in care and to prevent adverse outcomes, such as homelessness, for individuals with chronic mental health conditions. Investment in community-based interventions not only alleviates the strain on formal healthcare systems but also promotes a more inclusive and equitable approach to mental healthcare.

Community-based intervention provides care within society and family, fostering inclusion and treating mental health in familiar settings like community ...

Self-Help Support Groups

Self-help support groups are voluntary, community-based organizations that provide a platform for individuals with shared concerns to exchange support, insights, and practical strategies for coping with life challenges. Typically led by group members or paraprofessionals, these groups form a cornerstone of mental health care, especially in reaching populations that are underserved by traditional healthcare systems.
Accessibility and Cost-Effectiveness
One of the primary strengths of self-help groups is their accessibility. By leveraging community resources and operating at a low cost, they serve individuals who might otherwise face barriers to mental health services, such as those with limited financial means or lower levels of education. These groups offer an inclusive space where participants can openly share experiences, seek advice, and explore solutions in a non-judgmental environment.
The Power of Shared Experience
The effectiveness of self-help groups is rooted in their emphasis on shared experience. Participants gain unique insights from peers who have faced similar challenges, fostering a sense of credibility and understanding that professionals may not always provide. For instance, a rape survivor might find meaningful support and guidance from another survivor who has successfully navigated a similar recovery process. These interactions not only validate individual experiences but also enhance emotional resilience and promote self-efficacy.
Applications in Mental Health and Beyond
Self-help groups address a wide array of issues, including substance abuse, chronic illnesses such as heart disease or cancer, and psychological trauma. Alcoholics Anonymous (AA) exemplifies the impact of these groups, with research highlighting its role in reducing alcohol consumption through mechanisms such as enhanced social networks, improved self-efficacy, increased spirituality, and alleviation of negative emotions.
The Role of Online Platforms
Advances in technology have expanded the reach of self-help groups through online platforms, offering greater accessibility for individuals unable to attend in-person meetings. However, virtual settings pose unique challenges, including the risk of misinformation. In the absence of guidance from a trained professional, members may lack the expertise and knowledge to provide optimal advice. This increases the potential for harmful group dynamics, as evidenced by certain pro-anorexia communities. Effective moderation by group leaders can mitigate these risks, ensuring a safe and constructive environment for all members.
Self-help groups exemplify the value of peer-led initiatives in mental health care, bridging gaps in accessibility and fostering collective resilience through shared understanding and mutual support.

Self-help support groups are voluntary organizations where individuals with common interests meet regularly to discuss shared concerns and provide mutual ...

Family Therapy

Family therapy conceptualizes psychological challenges as arising from dysfunctional interactions within the family unit, rather than as isolated issues within individuals. This approach seeks to address and transform the patterns of communication, roles, and relationships within families to promote healthier dynamics and emotional well-being for all members.
Strategic Family Therapy
Strategic family therapy emphasizes resolving communication barriers and improving problem-solving abilities among family members. Therapists employ carefully planned tasks, known as directives, to alter dysfunctional interaction patterns. One notable technique is the use of paradoxical requests, where problematic behaviors are reframed in unexpected ways to elicit change. For example, a couple prone to frequent arguments might be instructed to argue more intentionally, thereby reframing their conflict as an expression of connection. This paradoxical approach often leads to reduced conflict and an improved relationship dynamic by altering the way family members perceive and engage in their interactions.
Structural Family Therapy
Structural family therapy focuses on reorganizing the family&#39;s hierarchical structure and boundaries to enhance functionality. Therapists actively participate in family activities to observe and modify interactions, fostering healthier dynamics. For instance, helping a teenager who initially sought their family&#39;s attention by refusing to eat to express their needs verbally, ultimately leading them to stop using food refusal as a way to seek affection. This direct engagement strengthens communication, reinforces healthy boundaries, and empowers the family to support each member&#39;s needs effectively.
Effectiveness and Applications
Research demonstrates that family therapy is as effective as individual therapy, offering distinct advantages for families dealing with relational or systemic issues. By addressing problems within their broader context, family therapy promotes growth and healing not just for individuals but for the family as a cohesive unit. Approaches such as strategic and structural therapy exemplify the flexibility and efficacy of this modality, making it a valuable tool in fostering healthier familial relationships and emotional resilience.

Family therapy views psychological problems as rooted in dysfunctional family systems rather than in an individual.
The primary focus of treatment is the ...

Rational Emotive Behavior Therapy

Cognitive-behavioral therapies (CBTs) are grounded in the belief that our thoughts profoundly influence our emotions and actions. Advocates of CBT emphasize three core assumptions: first, that cognitions are identifiable and measurable; second, that they are central to psychological functioning; and third, that irrational or maladaptive beliefs can be replaced with rational and adaptive ones. This transformative approach to therapy has paved the way for specific models such as Albert Ellis&#39;s Rational Emotive Behavior Therapy (REBT), which integrates both cognitive and behavioral elements to foster mental well-being.
The ABCs of Rational Emotive Behavior Therapy
Ellis introduced REBT in the mid-1950s as a pioneering cognitive-behavioral framework. At its core lies the ABC model, which outlines the interaction between activating events (A), belief systems (B), and emotional and behavioral consequences (C). For instance, two individuals receiving the same test score may exhibit vastly different responses due to disparities in their belief systems. Rational beliefs, characterized by flexibility and self-acceptance, contrast sharply with irrational beliefs, which often involve unrealistic demands and catastrophic thinking.
To address irrational beliefs, Ellis extended the ABC model to include disputation (D), effective new beliefs (E), and fostering desired feelings and behaviors (F). Therapists employing REBT actively challenge clients&#39; maladaptive beliefs and encourage rational rethinking. Assignments or &#8220;homework&#8221; often reinforce this process, such as tasks designed to confront and disprove fears tied to irrational thoughts.
Cognitive-Behavioral Therapy: Expanding on Rationality
CBT builds upon the principles of cognitive psychology and behaviorism, focusing on present cognitive and behavioral interactions rather than past influences. It posits that psychological disorders stem from illogical thought patterns, which, when restructured into logical and rational frameworks, lead to symptom alleviation. The three overarching goals of CBT include symptom relief, equipping clients with coping strategies, and fostering a shift from self-defeating to self-enhancing thoughts.
By blending cognitive interventions with behavioral techniques, CBT offers a robust, action-oriented approach to mental health, emphasizing the transformative power of rational thinking and adaptive behavior.

In the mid-1950s, Albert Ellis developed rational emotive behavior therapy or REBT, a key example of a cognitive-behavioral approach.
He introduced the ...

Electroconvulsive Therapy

Electroconvulsive therapy (ECT), or shock therapy, remains a critical biomedical intervention for severe, treatment-resistant depression. While its origins can be traced back to Hippocrates&#39; observations that malaria-induced convulsions alleviated mental illness, modern ECT has evolved significantly from its earlier, more primitive applications. First introduced in 1938 by Ugo Cerletti and his colleagues, ECT involves inducing controlled seizures using electrical currents. In its early years, patients were subjected to the procedure without anesthesia, leading to severe bodily convulsions and a barbaric reputation. Today, however, ECT is far more refined and safer due to anesthesia, muscle relaxants, and targeted stimulation.
The current ECT procedure involves administering a brief electric pulse, typically lasting less than a second, through electrodes placed on the patient&#39;s scalp. This electrical current triggers a seizure lasting approximately 60 seconds. Patients are rendered unconscious with anesthesia and muscle relaxants to prevent physical convulsions, ensuring minimal discomfort. Increasingly, the stimulation is applied to the brain&#39;s right hemisphere, reducing the risk of memory loss and cognitive impairments, which are among ECT&#39;s most debated side effects. Patients awaken shortly after the procedure with no memory of the treatment, and recovery occurs within 30 minutes.
ECT is primarily used for individuals with severe depression who do not respond to medication or psychotherapy. It is particularly effective for cases involving acute suicidality, offering rapid mood improvement. Studies report that after two to four weeks of treatments &#8212; typically three sessions per week &#8212; approximately 70% of patients experience significant relief. This success has been attributed to ECT&#39;s ability to reduce overactivity in brain regions associated with depression and potentially stimulate neurogenesis, promoting the growth of new neurons and synaptic connections.
Despite its effectiveness, ECT remains controversial due to its side effects, including memory loss and cognitive impairment. Though modern advancements, such as unilateral stimulation and refined protocols, have reduced these risks, they still warrant careful consideration. Long-term efficacy also remains uncertain, as relapses can occur, necessitating maintenance therapies like antidepressants or exercise. Nonetheless, ECT continues to save lives, especially in severe cases of depression where other treatments fail. For many, its benefits far outweigh the risks.

Electroconvulsive therapy, or ECT, commonly known as shock therapy, originated from Hippocrates&#39; observations in ancient Greece, who noted that ...

Beck's Cognitive Therapy

Cognitive therapy is a psychological approach designed to address distortions in thinking, which can lead to negative emotions and unrealistic beliefs. These cognitive distortions often influence how individuals interpret and respond to situations, exacerbating emotional distress. Below are some prevalent cognitive distortions, their characteristics, and examples of how they manifest in thought processes.
Arbitrary Inference
Arbitrary inference involves making conclusions without sufficient evidence, often based solely on personal assumptions. This type of distortion disregards facts and relies on conjecture. For example, an individual may interpret a canceled lunch appointment as evidence that their friend is seeing someone else, despite having no supporting evidence. This tendency to jump to conclusions can lead to unwarranted anxiety or mistrust.
Selective Thinking
Selective thinking occurs when a person fixates on one aspect of a situation, ignoring other relevant details that might provide balance or perspective. For instance, a student might receive praise for their work but focus entirely on a minor critique, concluding that their performance was poor. This cognitive bias limits the individual&#39;s ability to see the broader context of their achievements or the constructive nature of feedback.
Overgeneralization
Overgeneralization involves drawing broad, often exaggerated conclusions based on a single incident. For example, someone reprimanded at work might irrationally assume that their work relationships are doomed and envision a cascade of negative outcomes. This distortion perpetuates feelings of hopelessness and unwarranted despair.
Magnification and Minimization
In this distortion, individuals amplify the significance of negative events while downplaying positive ones. For example, a student who consistently excels academically might catastrophize a single mediocre grade as a sign of inevitable failure, disregarding their overall success. This imbalance skews self-assessment and fosters unwarranted negative self-perceptions.
Personalization
Personalization involves taking unwarranted responsibility for external events. For example, a person might attribute their partner&#39;s bad mood to their actions, ignoring external factors such as work-related stress. This distortion often results in misplaced guilt or self-blame.
Cognitive therapists aim to address these distortions by encouraging clients to evaluate their beliefs critically. Through structured questioning, such as examining the origin or evidence of a belief, clients are guided to identify and challenge illogical patterns. This process fosters more balanced and realistic thinking, improving emotional well-being and resilience.

Cognitive therapy, developed by Aaron T. Beck, addresses distorted thinking and unrealistic beliefs, particularly in depression.
Some of the common ...

Cognitive Therapy

Cognitive therapy, pioneered by Aaron T. Beck in the 1960s, is a structured approach to addressing psychological distress by focusing on the influence of thoughts on emotions and behaviors. All cognitive therapies involve the basic assumption that human beings have control over their feelings, and that how individuals feel about something depends on how they think about it. Unlike psychoanalytic methods that delve into unconscious processes or humanistic approaches emphasizing self-actualization, cognitive therapy targets distorted or dysfunctional thought patterns, aiming to restructure these to alleviate maladaptive behaviors and emotional responses.
Principles of Cognitive Therapy
Central to cognitive therapy is the concept of cognitive restructuring, which involves identifying and modifying distorted thinking patterns (cognitive distortions). For example, a client may interpret a single academic failure as indicative of global incompetence, leading to feelings of worthlessness. Through guided questioning, therapists challenge these irrational beliefs and help clients develop more accurate, rational perspectives. This active and structured process distinguishes cognitive therapy as an action-oriented approach rather than one focused on uncovering historical psychological roots.
Application to Depression and Other Disorders
Initially developed to treat depression, cognitive therapy has demonstrated effectiveness across a range of psychological disorders. Beck&#39;s work emphasized the role of self-defeating attitudes and negative automatic thoughts in perpetuating depressive states, even amidst positive life circumstances. By addressing these maladaptive cognitions, clients can reframe their interpretations of situations, reducing distress and promoting healthier emotional responses.

Cognitive therapy is a form of psychotherapy that emphasizes the role of thoughts in causing emotional distress and maladaptive behaviors.
It aims to ...

Group Therapy

Group therapy is a sociocultural approach to psychological treatment, where individuals with shared psychological challenges come together under the guidance of a mental health professional. This therapeutic modality offers unique opportunities for individuals to connect, share, and grow within the context of a supportive group. By fostering mutual understanding and collaboration, group therapy can address a range of psychological concerns effectively, often complementing or surpassing the benefits of individual therapy.
Benefits of Group Therapy
Group therapy promotes universality, helping participants realize that others share similar struggles, which can reduce feelings of isolation and shame. For instance, a child dealing with poor social skills may benefit from observing and practicing interpersonal techniques within a structured group setting. Similarly, a woman with postpartum depression might feel less guilt and more connection in a group of others facing the same challenges.
Altruism is another key feature: participants provide support, advice, and empathy to one another, which can enhance feelings of competence and efficacy. Additionally, the group environment fosters interpersonal learning, where individuals receive feedback from peers, enabling them to refine social behaviors and develop healthier interaction patterns. For those with specific needs, such as sexual abusers, group therapy offers a safe space for practicing social skills, modeling openness, and confronting harmful patterns.
Challenges and Considerations
While group therapy has significant advantages, it is not without challenges. Participants may initially feel reluctant to share personal issues with strangers, and confidentiality concerns can arise if members disclose private information outside the group. Personality conflicts and disagreements within the group can also present obstacles. Despite these challenges, effective facilitation ensures a balanced and inclusive environment where everyone benefits from the group dynamic.
Applications and Formats
Group therapy can adopt various forms, including psychodynamic, humanistic, behavioral, or cognitive approaches. Psycho-educational groups address specific topics, such as coping with a family member&#39;s illness or overcoming bullying, often within school settings. Structured groups have defined goals and activities, while unstructured groups allow members to determine the focus collaboratively. These diverse formats cater to different therapeutic needs, making group therapy an adaptable and powerful tool for psychological growth and healing.

Group therapy is a sociocultural approach to treating psychological disorders, where individuals with similar issues participate in guided sessions led by ...

Drug Therapy

The advent of drug therapy has profoundly shaped modern mental health care, providing targeted treatments for a range of psychological disorders. Psychotherapeutic drugs, classified into antianxiety, antidepressant, and antipsychotic medications, address symptoms across anxiety disorders, mood disorders, and schizophrenia. While these medications have transformed patient outcomes, they require careful management due to their potential side effects and limitations.
Antianxiety Medications
Antianxiety drugs, commonly known as tranquilizers, include benzodiazepines such as Xanax, Valium, and Librium. These medications alleviate anxiety by binding to neurotransmitter receptors that are hyperactive during periods of distress. Although benzodiazepines act rapidly and are effective for short-term relief, they pose risks of addiction, drowsiness, impaired coordination, and potentially harmful interactions with alcohol and other drugs. Alternatives like buspirone (BuSpar) offer less addictive solutions but may take longer to provide symptomatic relief. Caution is essential in prescribing these medications, particularly for long-term use, due to their addictive potential.
Antidepressant Drugs
Antidepressants regulate mood by influencing brain neurotransmitters, particularly serotonin and norepinephrine. Types of antidepressants such as tricyclics and tetracyclics, named for their molecular structures, have demonstrated efficacy but come with significant side effects such as dizziness, memory issues, and faintness. Monoamine oxidase (MAO) inhibitors, though effective, are less commonly used due to dietary restrictions and risks of high blood pressure. More commonly prescribed are selective serotonin reuptake inhibitors (SSRIs), which target serotonin reabsorption, offering fewer side effects and broad applications for mood, anxiety, and even chronic pain disorders. However, withdrawal from SSRIs requires careful management to avoid severe symptoms.
Mood Stabilizers Medications
Lithium remains a cornerstone treatment for bipolar disorder, effectively managing manic episodes and stabilizing mood. Its therapeutic benefits are tempered by a narrow safety margin, requiring careful blood monitoring to avoid toxicity. Side effects such as weight gain, thyroid issues, and kidney complications are common, highlighting the need for patient adherence and regular medical supervision.
Antipsychotic Medications
Antipsychotics have revolutionized schizophrenia treatment by reducing symptoms such as hallucinations and agitation. Neuroleptics, the most widely used class, modulate dopamine pathways but are associated with severe side effects, including tardive dyskinesia, a condition characterized by involuntary facial and limb movements. Newer atypical antipsychotics, such as Clozaril and Risperdal, also target serotonin and have fewer side effects, but challenges remain in patient adherence and long-term symptom management. Combining medication with psychotherapy and skill-building therapies improves outcomes, emphasizing the importance of holistic care.
Drug therapies, while pivotal in psychiatric treatment, require personalized and cautious administration. Side effects, risk of dependency, and adherence issues necessitate a balanced approach, often integrating pharmacological interventions with psychotherapy for optimal results.

The development of psychotherapeutic drugs revolutionized mental healthcare, offering effective treatments for anxiety, mood disorders, and 
...

Humanistic Therapy

Humanistic therapies emphasize personal growth, self-understanding, and the fulfillment of human potential. Rooted in the belief that individuals inherently strive toward self-actualization, these approaches encourage clients to explore their feelings and experiences in a supportive, nonjudgmental environment. Humanistic therapies differ from psychodynamic approaches by focusing on conscious experiences, present circumstances, and the potential for self-improvement rather than past conflicts and unconscious drives.
Carl Rogers&#39; client-centered therapy is a cornerstone of humanistic psychotherapy. It aims to foster self-acceptance and unity between the client&#39;s actual self and ideal self. Therapists create a therapeutic environment characterized by three essential elements:
<ol>
	<li>Unconditional Positive Regard: Therapists affirm the inherent worth of clients, offering nonjudgmental acceptance to promote self-acceptance.</li>
	<li>Empathy: By deeply understanding and reflecting on the client&#39;s emotions, therapists help clients feel heard and validated.</li>
	<li>Genuineness: Therapists are authentic and transparent, fostering a genuine connection with the client.</li>
</ol>
Active listening and reflective speech are central techniques that allow clients to identify and articulate their feelings. For example, a therapist might mirror a client&#39;s grief or anger, encouraging deeper emotional exploration.
Gestalt therapy, developed by Fritz Perls, focuses on integrating conflicting aspects of the self to achieve wholeness. Techniques like the two-chair dialogue allow clients to confront and synthesize opposing parts of their personality, fostering authenticity and emotional balance. Gestalt therapy emphasizes the &#34;here and now,&#34; urging clients to take responsibility for their feelings and actions. Techniques such as the two-chair method in Gestalt therapy, where clients alternate speaking from different perspectives to address and resolve internal conflicts, help promote self-awareness and integration.
Existential therapy, exemplified by Viktor Frankl&#39;s logotherapy, explores meaning-making as a response to life&#39;s challenges. Frankl believed that even in dire circumstances, individuals could find purpose and maintain dignity. Existential therapists help clients confront themes like freedom, isolation, and mortality, encouraging personal responsibility and resilience.
Humanistic principles are integral to various contemporary approaches, including motivational interviewing, which leverages empathy and reflective listening to encourage behavior change. Whether addressing mental health conditions or lifestyle modifications, humanistic therapies remain influential in fostering emotional awareness, self-empowerment, and authentic living.

Humanistic therapy focuses on self-healing, conscious thoughts, the present, and self-fulfillment, encouraging individuals to realize their potential and ...

Modeling in Therapy

Modeling, a key technique in therapy, uses observational learning to help clients acquire and practice new skills by watching therapists demonstrate desired behaviors. This approach, rooted in Albert Bandura&#39;s concept of vicarious learning, plays a significant role in therapeutic interventions for various psychological conditions, including social anxiety, ADHD, and depression.
Participant Modeling
Participant modeling involves therapists demonstrating calm and effective behaviors in situations that clients find challenging. The therapist first models a constructive approach to the feared object or scenario and then guides the client through the same process step-by-step until the client gains the confidence to manage independently. This technique helps clients confront their fears in a controlled and supportive environment.
Assertion Training
Assertion training incorporates modeling to help individuals express their thoughts and feelings assertively while avoiding extremes of submissiveness and aggressiveness. This training teaches clients to advocate for themselves respectfully and effectively, ensuring that their needs and rights are recognized. The focus is on fostering assertiveness as the balance between passivity and hostility, a skill particularly valuable for those with social anxiety or interpersonal challenges.
Behavioral Rehearsal
Behavioral rehearsal, often integrated with assertion training, employs role-playing exercises to enhance the client&#39;s skills. The therapist assumes the role of a significant figure in the client&#39;s life, such as a supervisor or family member, allowing the client to practice responses in a simulated interaction. As a result, role reversal enables the therapist to model ideal verbal and nonverbal communication, illustrating not just what to say but also how to say it effectively. Feedback and coaching refine the client&#39;s performance, helping them build confidence and competence.
Applications Beyond Therapy
These techniques extend beyond therapy sessions by encouraging clients to apply learned skills in real-life situations. By practicing outside the therapeutic setting, clients consolidate their learning and improve their ability to handle social interactions. Modeling and social skills training are instrumental in managing conditions such as schizophrenia, autism spectrum disorders, and ADHD, where improved interpersonal and coping skills can significantly enhance quality of life.
Through structured observation, practice, and application, modeling serves as a powerful tool in helping clients overcome barriers and adopt constructive behaviors.

Modeling allows clients to learn by watching therapists demonstrate positive behaviors, such as maintaining eye contact during conversations.
Similarly, ...

Operant Conditioning Intervention

Operant conditioning serves as a foundational principle in therapeutic interventions aimed at modifying maladaptive behaviors. Central to this approach is the notion that behaviors, both adaptive and maladaptive, are learned through reinforcement. By analyzing the environmental factors that reinforce problematic behaviors, clinicians can design interventions to weaken these reinforcements and replace maladaptive behaviors with healthier alternatives.
In operant conditioning, behaviors that are reinforced tend to recur, whereas those that are not reinforced eventually diminish or become extinct. For example, obsessive-compulsive disorder (OCD) behaviors, such as compulsive checking rituals, are maintained through negative reinforcement. A compulsive action, like repeatedly checking if a door is locked, alleviates anxiety and prevents anticipated negative outcomes, reinforcing the behavior. Therapy based on operant conditioning addresses this by extinguishing avoidance learning. The individual is gradually exposed to situations without performing the compulsion, demonstrating that the feared outcomes do not occur. Simultaneously, relaxation training and alternative coping mechanisms are introduced to reduce anxiety, breaking the cycle of compulsive reinforcement.
Behavioral therapies based on operant principles are particularly effective for populations with limited cognitive abilities, such as children or adults with developmental disabilities. In treating autism spectrum disorder (ASD), behavioral therapies have proven highly effective. It is used to address self-injurious behaviors, promote communication, and enhance cognitive and language development. Research indicates that intensive early interventions can significantly improve outcomes for children with ASD.
One widely implemented operant conditioning technique is the token economy. This method is commonly used in controlled environments, such as psychiatric hospitals, to encourage positive behaviors. Tokens, which serve as secondary reinforcers, are awarded for desirable actions and can be exchanged for privileges or rewards. For instance, patients may earn tokens for completing daily tasks or engaging in social interactions, which they can later trade for amenities like extra leisure time or preferred activities. The structured reinforcement system of token economies fosters sustained behavioral improvements across diverse clinical settings.

Operant conditioning suggests that behaviors are shaped by their consequences.
Behaviors followed by positive outcomes are reinforced, such as a child ...

Psychodynamic Therapy

Psychodynamic therapies emphasize the exploration of unconscious processes and early childhood experiences as fundamental contributors to psychological difficulties. These therapies, deeply rooted in Freud&#39;s psychoanalytic theory, aim to uncover and resolve unconscious conflicts, granting individuals insights that promote emotional and behavioral healing. Contemporary psychodynamic approaches have evolved, integrating a broader range of influences and methodologies while still valuing the unconscious mind and the therapeutic relationship.
Freud&#39;s psychoanalysis is the cornerstone of psychodynamic therapies. He proposed that unconscious conflicts, often originating in childhood, manifest as present-day psychological problems. Through techniques such as free association, dream analysis, and interpretation, psychoanalysts endeavor to illuminate these hidden struggles.
Free Association encourages clients to articulate thoughts without censorship, facilitating the emergence of repressed emotions or memories. Freud viewed moments of resistance &#8212; when clients hesitated or avoided certain topics &#8212; as indicators of unresolved conflicts.
Dream Analysis involves interpreting dreams&#39; manifest content (the recalled narrative) to reveal their latent content or hidden unconscious meanings. Freud believed that dreams serve as a disguised outlet for repressed wishes, often rooted in sexual or aggressive instincts.
Interpretation entails uncovering symbolic meanings in clients&#39; words and actions and offering hypotheses about unconscious motivations that drive behaviors.
Freud highlighted the importance of transference, where clients project feelings toward significant figures in their lives onto the therapist. This phenomenon provides a window into relational patterns and unresolved emotions, which therapists can help clients process. Conversely, resistance reflects unconscious defense mechanisms that hinder therapy progress. Psychoanalysts work to address and understand these resistances, aiding clients in confronting difficult truths.
Modern psychodynamic therapies have shifted focus, often prioritizing the conscious mind and current relationships over Freud&#39;s emphasis on sexual conflicts. They explore recurring life patterns, significant past events, and distressing emotions to provide insight. Therapists, influenced by figures like Heinz Kohut, emphasize empathy and healthy therapeutic relationships as a means to foster self-understanding and emotional resilience. Contemporary practices also adapt to practical constraints, favoring weekly sessions over the intensive regimens of Freud&#39;s era.
This evolution reflects an enduring commitment to exploring the depths of the human psyche while embracing contemporary perspectives on mental health.

Psychodynamic therapy explores the unconscious mind, such as repressed memories, conflicts, and early childhood experiences, to understand current ...

Behavior Therapy

Behavior therapy incorporates diverse techniques rooted in classical conditioning principles to address maladaptive behaviors and anxiety disorders. These methods aim to reduce avoidance behaviors, foster adaptive coping mechanisms, and alter associations between stimuli and responses, making them effective in a wide range of therapeutic contexts.
Exposure therapy is a cornerstone of behavioral treatment for anxiety disorders. It involves systematic exposure to feared stimuli, either in real life, through visualization, or via virtual reality, to desensitize the individual. Gradual exposure, beginning with the least anxiety-provoking scenarios and progressing to more challenging ones, is designed to help clients build tolerance.
Systematic desensitization builds upon this by pairing exposure with relaxation techniques. For instance, someone with a fear of public speaking may practice relaxation while initially speaking to a single person and then gradually progressing to larger audiences, reducing anxiety through reciprocal inhibition.
Flooding involves directly confronting the most anxiety-inducing stimuli in a controlled setting to extinguish avoidance behaviors. Unlike graded exposure, flooding does not follow a hierarchical approach. For example, an individual with a phobia of dogs might be guided to interact with a calm and friendly dog immediately, enabling them to experience the absence of feared consequences, which helps diminish their fear response.
Aversive conditioning is employed to deter undesirable behaviors by pairing them with unpleasant experiences. For example, to address overeating, therapists may use aversive stimuli, such as a bitter taste, to create a negative association with the behavior. This method conditions the individual to avoid the maladaptive behavior due to its unpleasant consequences.
Relaxation techniques, including deep breathing and progressive muscle relaxation, are integral to these therapies. They work through reciprocal inhibition, whereby a physiological state incompatible with anxiety, such as relaxation, counteracts the anxious response. By combining relaxation with gradual or direct exposure, individuals can recondition their responses to previously feared stimuli, fostering long-term behavioral change.

In behavior therapy, a therapist employs principles of learning, such as classical and operant conditioning, to help clients change undesirable 
...

Psychotherapy

Psychotherapy is a versatile, nonmedical approach aimed at helping individuals address emotional, behavioral, and interpersonal issues to enhance their overall well-being. It can involve one-on-one sessions, couples counseling, or small group discussions with a therapist. The therapeutic process includes various techniques such as open discussion, interpretation of thoughts and behaviors, active listening, positive reinforcement, and role modeling. Psychotherapy aims to support individuals in understanding themselves better, whether or not they have diagnosed mental health conditions.
Insight Therapies
Insight therapies focus on uncovering the psychological motives behind behavior. By exploring unconscious processes, emotions, and past experiences, these therapies aim to help individuals better understand their actions and thought patterns. Psychodynamic therapy, based on Freud&#39;s psychoanalytic principles, delves into unresolved conflicts stemming from childhood. Humanistic therapy, developed by Carl Rogers, emphasizes personal growth and self-actualization, encouraging clients to explore their potential. Existential therapy addresses questions of meaning, freedom, and responsibility, while group therapy fosters interpersonal learning through shared experiences within a group setting.
Action Therapies
Action therapies, on the other hand, focus on modifying harmful thoughts and behaviors without delving deeply into their origins. Cognitive and cognitive-behavioral therapies (CBT) are the most widely used action therapies. Cognitive therapy helps individuals identify and challenge distorted or irrational thought patterns, while CBT combines this cognitive restructuring with behavioral techniques. The aim is to replace negative thought patterns with healthier, more adaptive ones and to encourage positive behavioral changes. These therapies are highly effective in treating conditions such as depression, anxiety disorders, and phobias.

Psychotherapy is a nonmedical approach designed to help individuals recognize and address emotional, behavioral, and interpersonal problems to improve ...

Elements Crucial for Effective Psychotherapy

Research has highlighted several critical factors that influence the effectiveness of psychotherapy, such as the therapeutic alliance, the therapist, and the client.
The Therapeutic Alliance
The therapeutic alliance refers to the relationship between the therapist and the client. The alliance strengthens when the therapist and the client engage in a nurturing, supportive, trusting, empathetic, and respectful relationship, improving therapeutic outcomes. Therapists must monitor this relationship continuously, as studies suggest that clients who rate the alliance poorly are more likely to discontinue therapy or have negative experiences. Conversely, those who share a strong bond with their therapist are more likely to see successful outcomes.
The Therapist
The effectiveness of psychotherapy can depend significantly on the therapist&#39;s skill set and expertise. Experienced therapists deeply understand psychological issues and are committed to adapting their approach based on ongoing progress. Research also suggests that the compatibility between the therapist&#39;s style and the client&#39;s personality plays a crucial role in therapy success. For example, a more flexible and laid-back therapist may succeed with a client who resists change, while a directive approach may work better for others.
The Client
Another major determinant of therapeutic outcomes is the client&#39;s role in the process. Meta-analyses suggest that the client&#39;s participation is one of the most critical factors in determining success. While clients often seek therapy for life challenges, their strengths, skills, and motivation largely contribute to their progress. Research has consistently shown that therapy&#39;s success depends significantly on the client&#39;s engagement, and clients who fail to participate actively are more likely to experience unsatisfactory results.

Effective psychotherapy depends on three crucial elements&#8212; the therapeutic alliance, the therapist, and the client.
The therapeutic alliance refers ...

Treatment Strategies for Psychological Disorders

Treatment approaches for psychological disorders fall into three main categories: psychological, biological, and sociocultural. Each approach targets different aspects of mental health, requiring varying levels of education and training.
Psychological therapies focus on modifying emotions, thoughts, and behaviors through talking, interpreting, listening, rewarding, challenging, and modeling. Clinical psychologists, counselors, and social workers commonly practice psychotherapy. Clinical psychologists typically hold a Ph.D. or Psy.D., which involves years of graduate education, supervised clinical practice, and a clinical internship. Licensing and certification are two processes through which society regulates psychotherapy practitioners. Specific laws govern the requirements for obtaining a license or certification, ensuring that professionals meet specific educational and training standards. These regulations outline the necessary qualifications and mandate formal examinations to assess the practitioner&#39;s skills and competency before allowing them to practice.
Biological therapies, or biomedical therapies, aim to treat psychological disorders by altering physical body functions, often through medications. This approach views mental health disorders similarly to physical diseases, requiring medical intervention. Practitioners of biological therapies are generally medical doctors (MDs), with psychiatrists specializing in this field. Psychiatrists undergo medical school, residency, and specialized training in psychiatry. While both psychologists and psychiatrists can administer psychotherapy, only psychiatrists can prescribe medication. If medication is necessary, a psychotherapist may refer clients to a psychiatrist for prescriptions.
Sociocultural therapies emphasize the impact of social and cultural factors on mental health. This approach considers the individual&#39;s relationships, societal roles, and cultural influences in developing and treating psychological issues. Practitioners include psychotherapists, social workers, and psychiatric social workers, who are trained to intervene in the context of these social systems. Social workers typically hold a master&#39;s degree in social work (MSW), and psychiatric social workers receive additional training in mental health. Paraprofessionals, individuals without formal mental health qualifications but trained by professionals, can also assist, often bringing personal experience with specific disorders.

Treatment strategies for psychological disorders fall under three broad approaches - psychological, biological, and sociocultural.
The psychological ...

Conduct Disorder

Conduct disorder is a complex mental health diagnosis characterized by a repetitive and persistent pattern of behavior that violates societal norms, the rights of others, or age-appropriate rules. The diagnostic criteria for conduct disorder require the presence of at least three problematic behaviors within the past 12 months, with at least one occurring in the past six months. These behaviors are grouped into four categories: aggression toward people and animals; destruction of property; deceitfulness or theft; and serious violations of rules. The severity of symptoms, age of onset, and associated features all play crucial roles in understanding the disorder&#39;s impact and prognosis.
Diagnostic Features and Severity
The behaviors defining conduct disorder range from bullying, physical cruelty, and theft, to truancy and property destruction. Severity is categorized as mild, moderate, or severe, based on the number of symptoms and their impact on others. Childhood-onset conduct disorder, marked by symptoms before age 10, is associated with a poorer prognosis compared to adolescent-onset conduct disorder. Those with the specifier &#34;limited prosocial emotions&#34; &#8212; such as lack of remorse, callousness, or shallow affect &#8212; exhibit a more severe and persistent course.
Associated Factors and Risks
A combination of genetic, environmental, and temperamental factors influences conduct disorder. Risk factors include parental neglect, inconsistent discipline, exposure to violence, and association with delinquent peers. Neurobiological findings, such as reduced autonomic fear responses, and structural differences in brain regions associated with emotional regulation, have been observed but are not diagnostic. Co-occurring conditions, including ADHD, substance use disorders, and mood disorders, are common and can exacerbate the symptoms of conduct disorder.
Developmental Trajectory
Conduct disorder typically emerges during middle childhood or adolescence, often following oppositional defiant disorder. Symptoms evolve with age, beginning with less severe behaviors such as lying and escalating to more severe actions like theft and aggression. While the majority of cases remit by adulthood, childhood-onset conduct disorder is strongly predictive of antisocial personality disorder and other psychosocial difficulties later in life.
Sociocultural and Gender Considerations
The expression of conduct disorder behaviors differs by gender, with boys more likely to exhibit physical aggression and girls more often engaging in relational aggression or truancy. Cultural and environmental contexts, such as systemic oppression or high-crime areas, may influence the prevalence and manifestation of conduct disorder, necessitating careful diagnostic evaluation to avoid bias.
Conduct disorder presents significant challenges for affected individuals, families, and communities. Its association with academic failure, legal issues, and health risks underscores the importance of early intervention and comprehensive treatment approaches tailored to the individual&#39;s developmental and social context.

Conduct disorder involves a repetitive pattern of behavior violating others&#39; rights or societal norms, typically emerging in childhood or 
...

Intellectual Disability

Intellectual disability (ID) is a neurodevelopmental condition characterized by deficits in intellectual and adaptive functioning that manifest during the developmental period. This condition encompasses challenges in reasoning, memory, problem-solving, and learning, accompanied by impairments in everyday life skills, such as communication, self-care, and social interactions. Intellectual disability affects approximately 1% of the population in the United States, impacting an estimated 5 million individuals.
Assessment and Diagnosis
Historically, the diagnosis of intellectual disability was heavily reliant on IQ scores, with an IQ below 70 considered a diagnostic threshold. However, recent standards, such as those outlined in the DSM-5, prioritize adaptive functioning over rigid IQ thresholds. Current assessments evaluate impairments across three domains: conceptual, social, and practical skills. Conceptual abilities include literacy, numeracy, and time management, while social skills cover empathy, interpersonal communication, and compliance with social norms. Practical skills pertain to personal care, job responsibilities, and daily routines.
Adaptive functioning is evaluated in the context of the individual&#39;s life circumstances. For example, two individuals with similar IQ scores might differ significantly in functionality &#8212; one might live independently with minimal support, while the other might require institutional care. This shift in diagnostic criteria emphasizes functional capabilities rather than test scores, allowing for a more nuanced understanding of intellectual disability.
Causes and Classifications
The etiology of intellectual disability can be organic or cultural-familial. Organic causes include genetic disorders, such as Down syndrome and Fragile X syndrome, and prenatal exposure to alcohol or toxins,&#160; which result in fetal alcohol syndrome. Fetal alcohol syndrome is a condition that results from exposing a developing embryo to alcohol, and intelligence levels can range from below average to levels associated with intellectual disability. Environmental factors, such as malnutrition, lack of stimulation, and inadequate healthcare, often underlie cultural-familial intellectual disability. This type of intellectual disability, with no identifiable physical damage, typically results in milder impairments.
Classifications range from mild to profound, based on the severity of deficits. Individuals with mild ID may achieve partial independence with support, while those with profound ID often remain fully dependent on caregivers due to severe limitations in all adaptive domains.
Holistic Perspectives
While intellectual disability affects cognitive and adaptive skills, it does not diminish the individual&#39;s capacity for forming meaningful relationships and contributing to their community. Understanding and addressing their diverse needs through tailored support and interventions can significantly enhance their quality of life and social integration.

Intellectual disability, previously termed as mental retardation, has been defined by significant cognitive deficits&#8212;which have been established ...

Tree Identification: How To Use a Dichotomous Key

Source: Laboratories of Margaret Workman and Kimberly Frye - Depaul University
A dichotomous key is a tool that identifies items in nature, such as leaves. This method is based on the idea of choosing between two characteristics. The word dichotomous comes from two Greek words that mean &#8220;to divide into two parts.&#8221; In a dichotomous key for leaf identification, each pair of phrases describes different features of the leaf. Only one of the phrases correctly applies to the leaf being keyed out. The correct phrase leads to the next pair of phrases, or states the name of the tree from which the leaf came. Using a field guide to trees and the iTree National Tree Benefits Calculator helps to identify trees in a field investigation, which shows the significance of trees in terms of their environmental benefits, such as storm water management, increasing property value, energy efficiency, air quality, and carbon sequestration.

Identification d'arbre : comment utiliser une clé dichotomique

Source: Laboratories of Margaret Workman and Kimberly Frye - Depaul University
A dichotomous key is a tool that identifies items in nature, such as ...

Tree Survey: Point-Centered Quarter Sampling Method

A number of methods are available for sampling forest communities. Point-centered quarter is one such method. It is used to gather information on the density, frequency, and coverage of tree species found in a forest. This information provides the ability to estimate the number of individual trees encountered, how often a certain tree occurs, how common the tree is compared to other trees, and the size of the tree. Compared to the standard plot analysis, the point-centered quarter method is more efficient, which is a major advantage. In a fixed-area plot sampling, a small portion of the total area of the forest is examined. In this small subsample, the density is determined directly by counting and identifying each tree. The ratio between size of the subplot and the overall forest size is used to determine the density for the entire forest.

Enquête sur les arbres : méthode d'échantillonnage du quadrant centré sur un point

A number of methods are available for sampling forest communities. Point-centered quarter is one such method. It is used to gather information on the ...

Using GIS to Investigate Urban Forestry

Source: Laboratories of Margaret Workman and Kimberly Frye - Depaul University
Urban forests broadly include urban parks, street trees, landscaped boulevards, public gardens, river and coastal promenades, greenways, river corridors, wetlands, nature preserves, natural areas, shelterbelts of trees, and working trees at industrial brownfield sites. The history of urban trees begins with trees as landscape embellishment. Today, urban trees are seen as essential components of city infrastructure and critical to human life as food, housing, and other public utilities. Urban trees are now valued for the ecosystem services they provide (e.g., preventing erosion, air pollutant removal, oxygen, shade, etc.). Yet, to efficiently make use of these benefits, trees must reach maturity, as leaf number and size directly affect a tree&#8217;s ability to provide ecosystem services. Urban forestry has had to develop its own forestry methods to address the needs and challenges unique to urban trees as compared to their woodland counterparts.
The following excerpt from the USDA Forest Service illustrates the urban tree perspective and policies of federal government:

<blockquote>Urban forests are dynamic ecosystems that provide needed environmental services by cleaning air and water, helping to control storm water, and conserving energy. They add form, structure, beauty and breathing room to urban design, reduce noise, separate incompatible uses, provide places to recreate, strengthen social cohesion, leverage community revitalization, and add economic value to our communities... This natural life support system sustains clean air and water, biodiversity, habitat, nesting and travel corridors for wildlife, and connects people to nature.</blockquote>

The management of urban trees is an interdisciplinary practice involving architecture, landscaping, planning, development, horticulture, etc. One particular discipline involved in forestry is geography, especially through the use of geographical information systems (GIS). GIS is a broad name encompassing any type of database containing geographical or spatial data that can be used to create computer-generated visual representations (e.g., maps). GIS allows for extensive data collection and management through ever-improving user interfaces, increasing the user-friendly quality of very large sets of information that can be accessed by many users. GIS applications range from free software and open access protocols, such as Google Earth, to proprietary systems, like ESRI ArcGIS. Using GIS to create and store geographical information also allows for easy data maintenance, because maps can be quickly updated by adding new information to the database and regenerating the visual output.

Utilisation du SIG pour enquêter sur la foresterie urbaine

Source: Laboratories of Margaret Workman and Kimberly Frye - Depaul University
Urban forests broadly include urban parks, street trees, landscaped ...

Proton Exchange Membrane Fuel Cells

Source: Laboratories of Margaret Workman and Kimberly Frye - Depaul University
The United States consumes a large amount of energy &#8211; the current rate is around 97.5 quadrillion BTUs annually. The vast majority (90%) of this energy comes from non-renewable fuel sources. This energy is used for electricity (39%), transportation (28%), industry (22%), and residential/commercial use (11%). As the world has a limited supply of these non-renewable sources, the United States (among others) is expanding the use of renewable energy sources to meet future energy needs. One of these sources is hydrogen.
Hydrogen is considered a potential renewable fuel source, because it meets many important criteria: it&#8217;s available domestically, it has few harmful pollutants, it&#8217;s energy efficient, and it&#8217;s easy to harness. While hydrogen is the most abundant element in the universe, it is only found in compound form on Earth. For example, it is combined with oxygen in water as H2O. To be useful as a fuel, it needs to be in the form of H2 gas. Therefore, if hydrogen is to be used as a fuel for cars or other electronics, H2 needs to be made first. Thusly, hydrogen is often called an &#8220;energy carrier&#8221; rather than a &#8220;fuel.&#8221;
Currently, the most popular way to make H2 gas is from fossil fuels, through steam reforming of hydrocarbons or coal gasification. This does not reduce dependence on fossil fuels and is energy intensive. A less-used method is by electrolysis of water. This also requires an energy source, but it can be a renewable source, like wind or solar power. In electrolysis, water (H2O) is split into its component parts, hydrogen gas (H2) and oxygen gas (O2), through an electrochemical reaction. The hydrogen gas made through the process of electrolysis can then be used in a Proton Exchange Membrane (PEM) fuel cell, generating an electric current. This electric current can be used to power motors, lights, and other electrical devices.

Piles à combustible à membrane d'échange de protons

Source: Laboratories of Margaret Workman and Kimberly Frye - Depaul University
The United States consumes a large amount of energy &#8211; the current ...

Biofuels: Producing Ethanol from Cellulosic Material

Source: Laboratories of Margaret Workman and Kimberly Frye - Depaul University
In this experiment, cellulosic material (such as corn stalks, leaves, grasses, etc.) will be used as a feedstock for the production of ethanol.&#160;The cellulosic material is first pretreated (ground and heated), digested with enzymes, and then fermented with yeast.&#160;Ethanol production is monitored using an ethanol probe.&#160;The experiment can be extended to optimize ethanol production by varying the feedstock used, pretreatment conditions, enzyme variation, yeast variation, etc.&#160;An alternative method of monitoring the reaction is to measure the carbon dioxide produced (using a gas sensor) instead of the ethanol.&#160;As a low-tech alternative, glucose meters (found in any drug store) can be used to monitor the glucose during the process, if an ethanol probe or carbon dioxide gas sensor is not available.
With an increased emphasis on &#8216;inquiry-based learning&#8221;, scientific probes are becoming more popular.&#160;Handheld devices like the Vernier Lab Quest used in conjunction with a variety of probes (such as those for conductivity, dissolved oxygen, voltage, and more) allow for less focus on collecting data and/or making graphs and more on analyzing the data and making predictions.&#160;Another advantage is that these are small and lightweight and can be taken into the field for measurements.

Biocarburants : produire de l'éthanol à partir de matière cellulosique

Source: Laboratories of Margaret Workman and Kimberly Frye - Depaul University
In this experiment, cellulosic material (such as corn stalks, leaves, ...

Testing For Genetically Modified Foods

Source: Laboratories of Margaret Workman and Kimberly Frye - Depaul University
Genetic modification of foods has been a controversial issue due to debated concerns over health and environmental safety. This experiment demonstrates technical understanding of how food DNA is genetically identified, allowing for educated decision making about the safety and potential dangers of using genetically modified organisms (GMOs) in food supplies.
Polymerase Chain Reaction (PCR) is used to amplify food DNA to test for the presence of genetically modified DNA in food products. Presence of specific DNA bands is detected by using gel electrophoresis to pull extracted food DNA through a 3% agarose gel, a concentration dense enough to separate the bands of DNA containing the genetically modified DNA. Several controls are used in the electrophoresis procedure to ensure DNA is successfully extracted from test foods (plant primer), and to provide known examples of both genetically modified DNA (purchased genetically modified DNA) and non-genetically modified DNA (purchased certified non-GMO food control).

Identifying Genetically Modified Foods Using PCR

Tests pour identifier les aliments génétiquement modifiés

Source: Laboratories of Margaret Workman and Kimberly Frye - Depaul University
Genetic modification of foods has been a controversial issue due to debated ...

Turbidity and Total Solids in Surface Water

Source: Laboratories of Margaret Workman and Kimberly Frye - Depaul University
Turbidity and total solids are related measurements addressing clarity of surface waters. Turbidity is an indirect measure of water clarity that determines the amount of light that can pass through the water. Total solids is a direct measurement of solid particles suspended in water determined by weight.
High levels of turbidity and total solids are caused by soil erosion, waste discharge, runoff, or changes in ecological communities including algal growth or abundance of benthic organisms that can disrupt sediments up into the water. Higher levels of turbidity and suspended solids can lower water quality by absorbing heat causing an increase in water temperature and a decrease in oxygen levels (warm water holds less oxygen). These conditions can also cause a decrease in photosynthesis as less sunlight penetrates the water, making the water unable to support some aquatic life. Suspended solids can also clog gills, smother eggs, reduce growth rates, and disrupt microhabitats of many aquatic organisms.
One method of measuring turbidity includes using a Secchi disk. A Secchi disk is a metal disk with alternate black and white quarters (Figure 1). It is attached to a rope that has one-foot markings along it. The disk is dropped into water until it can no longer be seen (Figure 2). The drawback of this method is that it must be done in the field and ideal protocol requires sunny conditions and that the testing area be shaded. In addition, if there is a large distance between the riverbank and the water level, it is difficult to use the Secchi disk. By using turbidity tubes, one can collect water and then perform the turbidity measurements back in the laboratory.
<img alt="Figure 1" src="/files/ftp_upload/10015/10015fig1.jpg" /> 
Figure 1. The modified Secchi disk design used in freshwater.
<img alt="Figure 2" src="/files/ftp_upload/10015/10015fig2.jpg" /> 
Figure 2. Different kinds of Secchi disk. A marine style one on the left and the freshwater version on the right

Turbidité et solides totaux dans les eaux de surface

Source: Laboratories of Margaret Workman and Kimberly Frye - Depaul University
Turbidity and total solids are related measurements addressing clarity of ...

Dissolved Oxygen in Surface Water

Source: Laboratories of Margaret Workman and Kimberly Frye - Depaul University
Dissolved oxygen (DO) measurements calculate the amount of gaseous oxygen dissolved in surface water, which is important to all oxygen-breathing life in river ecosystems, including fish species preferred for human consumption (e.g. bluegill and bass), as well as decomposer species critical to the recycling of biogeochemical materials in the system.
The oxygen dissolved in lakes, rivers, and oceans is crucial for the organisms and creatures living in it. As the amount of dissolved oxygen drops below normal levels in water bodies, the water quality is harmed and creatures begin to die. In a process called eutrophication, a body of water can become hypoxic and will no longer be able to support living organisms, essentially becoming a &#8220;dead zone.&#8221;
Eutrophication occurs when excess nutrients cause algae populations to grow rapidly in an algal bloom. The algal bloom forms dense mats at the surface of the water blocking out two essential inputs of oxygen for water: gas exchange from the atmosphere and photosynthesis in the water due to the lack of light below the mats. As dissolved oxygen levels decline below the surface, oxygen-breathing organisms die-off in large amounts, creating an increase in organic matter. The excess organic matter causes an increase in the oxygen-breathing decomposer populations in the benthic zone, which further depletes the remaining dissolved oxygen levels during the metabolic decomposition activity. Once the oxygen levels become this low, mobile oxygen-breathing species (e.g. fish) will move away, leaving no aerobic life in the water and creating a dead zone.
The Azide-Winkler titration method uses titration to determine the concentration of an unknown in a sample. Specifically, sodium thiosulfate is used to titrate iodine, which can be stoichiometrically related to the amount of dissolved oxygen in a sample.

Measuring Dissolved Oxygen in Water by Azide-Winkler Method

Oxygène dissous dans les eaux de surface

Source: Laboratories of Margaret Workman and Kimberly Frye - Depaul University
Dissolved oxygen (DO) measurements calculate the amount of gaseous oxygen ...

Nutrients in Aquatic Ecosystems

Source: Laboratories of Margaret Workman and Kimberly Frye - Depaul University
Nitrogen and phosphorus are essential plant nutrients found in aquatic ecosystems and both are monitored as a part of water quality testing because in excess amounts they can cause significant water quality problems.&#160;
Nitrogen in water is measured as the common form nitrate (NO3-) that is dissolved in water and readily absorbed by photosynthesizers such as algae. The common form of phosphorus measured is phosphate (PO43-), which is strongly attracted to sediment particles as well as dissolved in water. In excess amounts, both nutrients can cause an increase in aquatic plant growth (algal bloom, Figure 1) that can disrupt the light, temperature, and oxygen levels in the water below and lead to eutrophication and hypoxia (low dissolved oxygen in water) forming a &#8220;dead zone&#8221; of no biological activity. Sources of nitrates and phosphorus include wastewater treatment plants, runoff from fertilized lawns and agricultural lands, faulty septic systems, animal manure runoff, and industrial waste discharge.
<img alt="Figure 1" src="/files/ftp_upload/10023/10023fig1.jpg" /> 
Figure 1. Algal bloom 
Taken in 2011, the green scum shown in this image was the worst algae bloom Lake Erie has experienced in decades. Record torrential spring rains washed fertilizer into the lake, promoting the growth of microcystin producing cyanobacteria blooms. Vibrant green filaments extend out from the northern shore.

Eutrophication, Measuring Nitrate and Phosphate in Water

Nutriments dans les écosystèmes aquatiques

Source: Laboratories of Margaret Workman and Kimberly Frye - Depaul University
Nitrogen and phosphorus are essential plant nutrients found in aquatic ...

Measuring Tropospheric Ozone

Source: Laboratories of Margaret Workman and Kimberly Frye - Depaul University
Ozone is a form of elemental oxygen (O3), a molecule of three oxygen atoms bonded in a structure that is highly reactive as an oxidizing agent. Ozone occurs in both the stratosphere and the troposphere levels of the atmosphere. When in the stratosphere (located approximately 10-50 km from the earth&#8217;s surface), ozone molecules form to the ozone layer and help prevent harmful UV rays from reaching Earth&#8217;s surface. In lower altitudes of the troposphere (surface - approximately 17 km), ozone is harmful to human health and is considered an air pollutant contributing to photochemical smog (Figure 1). Ozone molecules can cause damage directly by harming respiratory tissue when inhaled or indirectly by harming plant tissues (Figure 2) and softer materials including tires on automobiles.
Outdoor tropospheric ozone is formed at ground level when nitrogen oxides (NOx) and volatile organic compounds (VOCs) from automobile emissions are exposed to sunlight. Consequently, health concerns over ozone concentrations escalate in sunny conditions or when and where automobile use is increased.
Reaction: NO2 + VOC + sunlight &#8594;&#160;O3 (+ other products)
Indoor tropospheric ozone is formed when electrical discharges from equipment using high voltages (e.g. ionic air purifiers, laser printers, photocopiers) break down the chemical bonds of the atmospheric oxygen (O2) in the air surrounding the equipment:
O2 &#8594; 2 O
The free radicals of oxygen in and around electrical discharge recombine to create ozone (O3).
2 O + 2 O2&#8594; 2 O3
<img alt="Figure 1" src="/files/ftp_upload/10024/10024fig1.jpg" /> 
Figure 1: Golden Gate Bridge panorama
Characteristic coloration for smog in California in the beige cloud bank behind the Golden Gate Bridge. The brown coloration is due to the NOx in the photochemical smog.
<img alt="Figure 2" src="/files/ftp_upload/10024/10024fig2.jpg" /> 
Figure 2: Plants damaged by ozone. Top row is normal, bottom row has been exposed to ozone.

Mesurer l'ozone troposphérique

Source: Laboratories of Margaret Workman and Kimberly Frye - Depaul University
Ozone is a form of elemental oxygen (O3), a molecule of three oxygen atoms ...

Determination Of NOx in Automobile Exhaust Using UV-VIS Spectroscopy

Source: Laboratories of Margaret Workman and Kimberly Frye - Depaul University
In the troposphere, ozone is naturally formed when sunlight splits nitrogen dioxide (NO2):
NO2 + sunlight &#8594; NO + O
O + O2 &#8594; O3
Ozone (O3) can go on to react with nitric oxide (NO) to form nitrogen dioxide (NO2) and oxygen:
NO + O3 &#8594; NO2 + O2
This results in no net gain of ozone (O3). However, with the anthropogenic production of ozone forming precursors (NO, NO2, and volatile organic compounds) through the combustion of fossil fuels, elevated levels of ozone in the troposphere have been found. Motor vehicle exhaust is a significant source of these ozone forming precursors: NO, NO2, and volatile organic compounds (VOCs). For example, mobile sources make up nearly 60% of NO + NO2 emissions.
At the high temperatures found in a car&#8217;s combustion chamber, nitrogen and oxygen from the air react to form nitric oxide (NO) and nitrogen dioxide (NO2):
N2(g) + O2 (g)&#8594; 2 NO(g)
2 NO(g) + O2(g)&#8594; 2 NO2(g)
The nitric oxide (NO) emitted in the car exhaust is gradually oxidized to nitrogen dioxide (NO2) in ambient air. This mixture of NO and NO2 is often referred to as NOx. When NOx reacts with volatile organic compounds in the atmosphere in the presence of sunlight, tropospheric ozone forms, as seen in this simplified chemical reaction:
NOx + VOCs + sunlight &#8594; O3 + other products
This noxious mixture of air pollution, which can include aldehydes, peroxyacetyl nitrates, ozone, VOCs, and NOx, is called photochemical smog. Ozone is the largest component of photochemical smog. This smog is found in all modern cities, but it&#8217;s found especially in cities with sunny, warm, dry climates and large numbers of motor vehicles. The yellow-brown color of smog in the air is due in part to the nitrogen dioxide present, since this gas absorbs visible light near 400 nm (Figure 1).
Short-term NO2 exposure (30 min to 1 day) leads to adverse respiratory effects in healthy people and increased respiratory symptoms in people with asthma. NOx reacts with ammonia and other compounds to form particulates. These small particles can penetrate the lungs and cause respiratory problems, including emphysema and bronchitis. Individuals who spend a lot of time on the road or who live near a roadway experience considerably higher exposure to NO2.
Due to the impact it has on human health and the environment, the U.S. Environmental Protection Agency (EPA) has classified NO2 as a criteria pollutant and has set the primary standard at 100 ppb (98th percentile of 1-h daily maximum concentrations, averaged over 3 years) and 53 ppb (annual mean). Considering that on-road vehicles account for approximately 1/3 of NOx emissions in the U.S., automobile emissions are therefore regulated through the Clean Air Act. The U.S. EPA established emission standards that automobile manufacturers must follow when producing cars. Currently, Tier 2 emission standards set that manufacturers must have fleet average NOx emissions of no more than 0.07 g/mile.
One way manufacturers meet this standard is by using catalytic converters on their cars. This device is placed between the engine and the tailpipe. The exhaust stream passes through the catalytic converter and is exposed to a catalyst. A reduction catalyst of platinum and rhodium is used to reduce the NOx concentration in the exhaust. When an NO or NO2 molecule in the exhaust contacts the catalyst, the nitrogen atom is grabbed off the molecule and held onto by the catalyst. The oxygen is freed and forms O2. The nitrogen atom on the catalyst binds with another nitrogen atom held on the catalyst to form N2.
Catalytic converters have greatly reduced the emissions of NOx from car exhaust &#8211; up to 80% reduction, when performing properly. However, they only work when they have reached a fairly high temperature. Therefore, when doing a cold start of a car, the catalytic converter is removing virtually no NOx. It isn&#8217;t until the catalytic converter reaches higher temperatures that it effectively removes the NOx from the exhaust stream. Catalytic converters do not work on diesel passenger cars due to the lean conditions under which they operate. In addition, the sulfur in diesel fuel also deactivates the catalyst. The NOx in diesel engines are reduced mainly through the exhaust gas recirculation (EGR) valve, which cools the temperature of the combustion gases. As a result, diesel cars generally emit more NOx than gasoline cars.
<img alt="Figure 1" src="/files/ftp_upload/10076/10076fig1.jpg" /> 
Figure 1. Characteristic coloration for smog in California in the beige cloud bank behind the Golden Gate Bridge. The brown coloration is due to the NOx in the photochemical smog.

Determination Of NOx in Automobile Exhaust Using UV-VIS Spectroscopy

Détermination des NOx dans les gaz d'échappement des voitures à l'aide de la spectroscopie UV-VIS

Source: Laboratories of Margaret Workman and Kimberly Frye - Depaul University
In the troposphere, ozone is naturally formed when sunlight splits nitrogen ...

Lead Analysis of Soil Using Atomic Absorption Spectroscopy

Source: Laboratories of Margaret Workman and Kimberly Frye - Depaul University
Lead occurs naturally in soil, in levels ranging from 10-50 ppm. However, with the widespread use of lead in paint and gasoline in addition to contamination by industry, urban soils often have concentrations of lead significantly greater than background levels &#8211; up to 10,000 ppm in some places. Ongoing problems arise from the fact that lead does not biodegrade, and instead remains in the soil.
Serious health risks are associated with lead poisoning, where children are particularly at risk. Millions of children in the U.S. are exposed to soil containing lead. This exposure can cause developmental and behavioral problems in children. These problems include learning disabilities, inattention, delayed growth, and brain damage. The Environmental Protection Agency has set a standard for lead in soil at 400 ppm for play areas and 1,200 ppm for non-play areas.
Lead is also of concern in soil, when it&#8217;s used for gardening. Plants take up lead from the soil. Therefore, vegetables or herbs grown in contaminated soil can lead to lead poisoning. In addition, contaminated soil particles can be breathed in while gardening or brought into the house on clothing and footwear. It is recommended that soils with lead levels greater than 400 ppm should not be used for gardening. It is further recommended that soil with lead levels between 100 and 400 ppm not be used for leafy vegetables or herbs, because lead can be stored in the leaves. On a similar note, root vegetables should not be grown in this soil, because lead can also accumulate in plant roots.

Analyse du plomb provenant du sol à l'aide de la spectroscopie d'absorption atomique

Source: Laboratories of Margaret Workman and Kimberly Frye - Depaul University
Lead occurs naturally in soil, in levels ranging from 10-50 ppm. However, ...

Carbon and Nitrogen Analysis of Environmental Samples

Source: Laboratories of Margaret Workman and Kimberly Frye - Depaul University
Elemental Analysis is a method used to determine elemental composition of a material. In environmental samples such as soils, scientists are particularly interested in the amounts of two ecologically important elements, nitrogen and carbon. Elemental analysis by the flash combustion technique works by oxidizing the sample with a catalyst through combustion in a high-temperature chamber. The products of combustion are then reduced to N2 and CO2 and detected with a thermal conductivity detector.
Unlike other methods for total nitrogen determination (Kjeldahl method) and total carbon determination (Walkley-Black, Heanes or Leco methods), the flash combustion technique does not use toxic chemicals and is therefore much safer to use.
This video will demonstrate combustion-based elemental analysis using the Flash EA 1112 instrument from Thermo Fisher Scientific.

Analyse du carbone et de l'azote des échantillons environnementaux

Source: Laboratories of Margaret Workman and Kimberly Frye - Depaul University
Elemental Analysis is a method used to determine elemental composition of a ...

Soil Nutrient Analysis: Nitrogen, Phosphorus, and Potassium

Source: Laboratories of Margaret Workman and Kimberly Frye - Depaul University
In this experiment, three soil macronutrients are chemically extracted, combined with color-based reagents, then analyzed using color to determine the nutrient concentration present in the soil sample.
Nitrogen, phosphorus, and potassium are the main components of soil fertilizer. These methods isolate each nutrient from the soil into a solution that can be analyzed using turbidity and color to determine the concentration of nutrients present in the soil sample. Knowing present concentration informs environmental scientists of a nutrient deficiency or surplus in soils used to support plant production, and also provides general insight into basic biogeochemical cycles of an ecosystem.

Analyse des éléments nutritifs du sol : azote, phosphore et potassium

Source: Laboratories of Margaret Workman and Kimberly Frye - Depaul University
In this experiment, three soil macronutrients are chemically extracted, ...

Analysis of Earthworm Populations in Soil

Source: Laboratories of Margaret Workman and Kimberly Frye - Depaul University
Using mustard, Lumbricus terrestris earthworm populations can be sampled directly from soil depths without landscape disturbance or toxicity. Earthworms can then be counted for data and statistical analysis using a bar graph and student&#8217;s t-test.
Monitoring earthworm populations is a vital technique for environmental scientists, as multiple species of earthworms (most notably those from the suborder Lumbricina) have been invasively spreading throughout North America and South America. Exotic earthworms can be found on nearly every land mass and in nearly every ecosystem on the planet, and where and when these species become invasive has been a focus of international environmental research.1
Ecological invasion typically lowers biodiversity of an ecosystem by directly outcompeting, endangering, or otherwise contributing to the extirpation of native species. As ecosystem engineers, invasive earthworm species alter the cycling of nutrients through decomposition rates of organic matter on the upper horizons of soil, where plant roots mine for nutrients. Invasive Lumbricus species have both extirpated native earthworm species and have been shown to increase the available nitrogen concentration and rates of nitrogen in invaded soils.2 In a positive feedback loop, accelerated levels of nitrogen in turn make the system more hospitable to invasive plant species that are adapted to high levels of nitrogen compared to native plant species, and will outcompete natives in a phenomenon known as &#8220;invasion meltdown.&#8221; An invasion meltdown relationship has been proposed for invasive earthworm species Lumbricus terrestris (European earthworm) and an invasive plant species Rhamnus cathartica (European Buckthorn).3

Quadrat Sampling and Earthworm Population Analysis in Soil

Analyse des populations de vers de terre du sol

Source: Laboratories of Margaret Workman and Kimberly Frye - Depaul University
Using mustard, Lumbricus terrestris earthworm populations can be sampled ...

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