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Topic Review
Compartmental Models in Epidemiology
Compartmental models are a very general modelling technique. They are often applied to the mathematical modelling of infectious diseases. The population is assigned to compartments with labels – for example, S, I, or R, (Susceptible, Infectious, or Recovered). People may progress between compartments. The order of the labels usually shows the flow patterns between the compartments; for example SEIS means susceptible, exposed, infectious, then susceptible again. The origin of such models is the early 20th century, with important works being that of Ross in 1916, Ross and Hudson in 1917, Kermack and McKendrick in 1927 and Kendall in 1956 The models are most often run with ordinary differential equations (which are deterministic), but can also be used with a stochastic (random) framework, which is more realistic but much more complicated to analyze. Models try to predict things such as how a disease spreads, or the total number infected, or the duration of an epidemic, and to estimate various epidemiological parameters such as the reproductive number. Such models can show how different public health interventions may affect the outcome of the epidemic, e.g., what the most efficient technique is for issuing a limited number of vaccines in a given population.
  • 3.1K
  • 02 Dec 2022
Topic Review
Injection
An injection (often and usually referred to as a "shot" in US English, a "jab" in UK English, or a "jag" in Scottish English and Scots) is the act of administering a liquid, especially a drug, into a person's body using a needle (usually a hypodermic needle) and a syringe. An injection is considered a form of parenteral drug administration; it does not involve absorption in the digestive tract. This allows the medication to be absorbed more rapidly and avoid the first pass effect. There are many types of injection, which are generally named after the body tissue the injection is administered into. This includes common injections such as subcutaneous, intramuscular, and intravenous injections, as well as less common injections such as intraperitoneal, intraosseous, intracardiac, intraarticular, and intracavernous injections. Injections are among the most common health care procedures, with at least 16 billion administered in developing and transitional countries each year. Of these, 95% are used in curative care or as treatment for a condition, 3% are to provide immunizations/vaccinations, and the rest are used for other purposes, including blood transfusions. The term injection is sometimes used synonymously with inoculation, but injection does not only refer to the act of inoculation. Injections generally administer a medication as a bolus (or one-time) dose, but can also be used for continuous drug administration. After injection, a medication may be designed to be released slowly, called a depot injection, which can produce long-lasting effects. An injection necessarily causes a small puncture wound to the body, and thus may cause localized pain or infection. The occurrence of these side effects varies based on injection location, the substance injected, needle gauge, procedure, and individual sensitivity. Rarely, more serious side effects including gangrene, sepsis, and nerve damage may occur. Fear of needles, also called needle phobia, is also common and may result in anxiety and fainting before, during, or after an injection. To prevent the localized pain that occurs with injections the injection site may be numbed or cooled before injection and the person receiving the injection may be distracted by a conversation or similar means. To reduce the risk of infection from injections, proper aseptic technique should be followed to clean the injection site before administration. If needles or syringes are reused between people, or if an accidental needlestick occurs, there is a risk of transmission of bloodborne diseases such as HIV and hepatitis. Unsafe injection practices contribute to the spread of bloodborne diseases, especially in less-developed countries. To combat this, safety syringes exist which contain features to prevent accidental needlestick injury and reuse of the syringe after it is used once. Furthermore, recreational drug users who use injections to administer the drugs commonly share or reuse needles after an injection. This has led to the development of needle exchange programs and safe injection sites as a public health measure, which may provide new, sterile syringes and needles to discourage the reuse of syringes and needles. Used needles should ideally be placed in a purpose-made sharps container which is safe and resistant to puncture. Some locations provide free disposal programs for such containers for their citizens.
  • 3.1K
  • 04 Nov 2022
Topic Review
Soft Gelatin Capsules
The development of soft gelatin capsules (SGCs) dosage forms has attracted a great deal of interest in the oral delivery of poorly water-soluble drugs. This is attributed to the increased number of poorly soluble drugs in the pipeline, and hence the challenges of finding innovative ways of developing bioavailable and stable dosage forms. Encapsulation of these drugs into SGCs is one of the approaches that is utilized to deliver the active ingredients to the systemic circulation to overcome certain formulation hurdles. Once formulated, encapsulated drugs in the form of SGCs require suitable in vitro dissolution test methods to ensure drug product quality and performance.
  • 3.1K
  • 04 Mar 2021
Topic Review
Medical Model of Autism
The medical model of autism encourages continual research into the causes of autism, with the primary goal of finding a way to prevent or cure autism. This is a subset of the medical model of disability in general. The model advocates a variety of goals including increased awareness of autism prevalence, earlier and more accessible diagnosis, elimination of autistic behaviors through therapies such as applied behavior analysis, identification of environmental factors that may cause autism in infancy, and identification of a genetic marker to allow testing for autism in utero. Advocates for the medical model believe that autism is a disorder caused by genetic defects or environmental harm, that the value of talents attributed to autism does not outweigh the deficits, and that most autistic people would be better off if they were not autistic. For instance, then-president Liz Feld of Autism Speaks stated that one-third of people with autism also have a seizure disorder, half suffer serious digestive complications, 49 percent wander, and more than 30 percent are nonverbal. Many organizations subscribe to the medical model, most of which have non-profit status. The autism rights and neurodiversity movements are critics of the medical view.
  • 3.1K
  • 16 Nov 2022
Topic Review
Xanthine Oxidoreductase Activities
Xanthine oxidoreductase (XOR) is the enzyme that catalyzes the oxidation of hypoxanthine to xanthine and xanthine to uric acid. XOR is widely distributed throughout living organisms and is highly conserved in prokaryotic, plant, and animal species. XOR activity is very versatile, generating both pro-oxidant (primarily within the cell) and anti-oxidant (primarily in plasma) products.
  • 3.0K
  • 21 Sep 2020
Topic Review
Nonparametric Limits of Agreement
The assessment of agreement in method comparison and observer variability analysis of quantitative measurements is usually done by the Bland-Altman Limits of Agreement, where the paired differences are implicitly assumed to follow a normal distribution. Whenever this assumption does not hold, the 2.5% and 97.5% percentiles are obtained by quantile estimation. In the literature, empirical quantiles have been used for this purpose. In this simulation study, we applied both sample, subsampling, and kernel quantile estimators as well as other methods for quantile estimation to sample sizes between 30 and 150 and different distributions of the paired differences. The performance of 15 estimators in generating prediction intervals was measured by their respective coverage probability for one newly generated observation. Our results indicated that sample quantile estimators based on one or two order statistics outperformed all the other estimators and can be used for deriving nonparametric Limits of Agreement. For sample sizes exceeding 80 observations, more advanced quantile estimators, such as the Harrell-Davis and estimators of Sfakianakis-Verginis type, which use all the observed differences, performed likewise well, but may be considered intuitively more appealing than simple sample quantile estimators that are based on only two observations per quantile.
  • 3.0K
  • 27 Oct 2020
Topic Review
Health-Promoting Beverages
Tea, a beverage made from the processed leaves of the tea plant, Camellia sinensis, and herbal infusions, were primarily consumed to their pleasant taste. Nowadays, are also consumed due to the existence of nutraceutical compounds in the herbs used, such as polyphenols.
  • 2.9K
  • 30 Oct 2020
Topic Review
Dynamic-Maturational Model of Attachment and Adaptation
The dynamic-maturational model of attachment and adaptation (DMM) is a transdisciplinary model describing the effect attachment relationships can have on human development and functioning. It is especially focused on the effects of relationships between children and parents and between romantic/reproductive couples. It developed initially from attachment theory as developed by John Bowlby and Mary Ainsworth, and incorporated many other theories into a comprehensive model of adaptation to life's many dangers. The DMM was initially created by developmental psychologist Patricia McKinsey Crittenden and her colleagues including David DiLalla, Angelika Claussen, Andrea Landini, Steve Farnfield, and Susan Spieker. A main tenant of the DMM is that exposure to danger drives neural development and adaptation to promote survival. Danger includes relationship danger. In DMM-attachment theory, when a person needs protection or comfort from danger from a person with whom they have a protective relationship, the nature of the relationship generates relation-specific self-protective strategies. These are patterns of behavior which include the underlying neural processing. The DMM protective strategies describe aspects of the parent-child relationship, romantic relationships, and to a degree, relationships between patients/clients and long-term helping professionals.
  • 2.9K
  • 22 Nov 2022
Topic Review
Vascular Endothelial Growth Factors
Vascular endothelial growth factors (VEGFs) are primary regulators of blood and lymphatic vessels. Hemangiogenic VEGFs (VEGF-A, PlGF, and VEGF-B) target mostly blood vessels, while the lymphangiogenic VEGFs (VEGF-C and VEGF-D) target mostly lymphatic vessels. Blocking VEGF-A is used today to treat several types of cancer (“antiangiogenic therapy”). However, in other diseases, it would be beneficial to do the opposite, namely to increase the activity of VEGFs. For example, VEGF-A could generate new blood vessels to protect from heart disease, and VEGF-C could generate new lymphatics to counteract lymphedema. Clinical trials that tried to stimulate blood vessel growth in ischemic diseases have been disappointing so far, and the first clinical trials targeting the lymphatic vasculature have progressed to phase II. Antiangiogenic drugs targeting VEGF-A such as bevacizumab or aflibercept neutralize the growth factor directly. However, since VEGF-C and VEGF-D are produced as inactive precursors, novel drugs against the lymphangiogenic VEGFs could also target the enzymatic activation of VEGF-C and VEGF-D. Because of the delicate balance between too much and too little vascular growth, a detailed understanding of the activation of the VEGF-C and VEGF-D is needed before such concepts can be converted into safe and efficacious therapies.
  • 2.9K
  • 30 Mar 2021
Topic Review
Clinical Psychology
Clinical psychology is an integration of science, theory, and clinical knowledge for the purpose of understanding, preventing, and relieving psychologically-based distress or dysfunction and to promote subjective well-being and personal development. Central to its practice are psychological assessment, clinical formulation, and psychotherapy, although clinical psychologists also engage in research, teaching, consultation, forensic testimony, and program development and administration. In many countries, clinical psychology is a regulated mental health profession. The field is generally considered to have begun in 1896 with the opening of the first psychological clinic at the University of Pennsylvania by Lightner Witmer. In the first half of the 20th century, clinical psychology was focused on psychological assessment, with little attention given to treatment. This changed after the 1940s when World War II resulted in the need for a large increase in the number of trained clinicians. Since that time, three main educational models have developed in the USA—the Ph.D. Clinical Science model (heavily focused on research), the Ph.D. science-practitioner model (integrating scientific research and practice), and the Psy.D. practitioner-scholar model (focusing on clinical theory and practice). In the UK and the Republic of Ireland, the Clinical Psychology Doctorate falls between the latter two of these models, whilst in much of mainland Europe, the training is at the masters level and predominantly psychotherapeutic. Clinical psychologists are expert in providing psychotherapy, and generally train within four primary theoretical orientations—psychodynamic, humanistic, cognitive behavioral therapy (CBT), and systems or family therapy. Clinical psychology is distinguished from psychiatry. Although practitioners in both fields are mental health professionals, clinical psychologists treat mental disorders through talk therapy and have a doctorate in Psychology or a Doctor of Psychology degree but cannot prescribe medicine. Psychiatrists are medical doctors who treat mental disorders through medication and have a medical degree. Five states, Louisiana, New Mexico, Illinois, Iowa, and Idaho, allow clinical psychologists to prescribe certain medications with completion of medical training, whereas most states only allow psychiatrists to prescribe medicine.
  • 2.8K
  • 01 Nov 2022
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