Your browser does not fully support modern features. Please upgrade for a smoother experience.
Subject:
All Disciplines Arts & Humanities Biology & Life Sciences Business & Economics Chemistry & Materials Science Computer Science & Mathematics Engineering Environmental & Earth Sciences Medicine & Pharmacology Physical Sciences Public Health & Healthcare Social Sciences
Sort by:
Most Viewed Latest Alphabetical (A-Z) Alphabetical (Z-A)
Filter:
All Topic Review Biography Peer Reviewed Entry Video Entry
Topic Review
Cellular Senescence
Cellular senescence is a hallmark of aging. Accumulation of senescent cells promotes aging and triggers age-related disorders.
  • 1.5K
  • 26 Jan 2021
Topic Review
Basic Helix-Loop-Helix (bHLH) in Arabidopsis
The basic helix-loop-helix (bHLH) transcription factor family is one of the largest transcription factor gene families in Arabidopsis thaliana, and contains a bHLH motif that is highly conserved throughout eukaryotic organisms. Members of this family have two conserved motifs, a basic DNA binding region and a helix-loop-helix (HLH) region. These proteins containing bHLH domain usually act as homo- or heterodimers to regulate the expression of their target genes, which are involved in many physiological processes and have a broad range of functions in biosynthesis, metabolism and transduction of plant hormones.
  • 1.5K
  • 16 Jul 2021
Topic Review
Applications of Thermal Plasma Waste Treatment
Non-thermal as well as thermal plasmas are used for the processing of materials and waste. Thermal (hot) plasmas are characterized by their high energy density and by the equal temperatures of the electrons and the heavy particles, i.e., thermal plasmas are in local thermodynamic equilibrium. Non-thermal plasmas (also called cold plasmas), on the other hand, are non-equilibrium ionized gases, which are characterized by lower energy densities and by the large difference between the electron temperature and the temperature of the heavy particles.
  • 1.5K
  • 25 Jul 2022
Topic Review
The Role of Sphingomyelin in Motor Neuron Diseases
Amyotrophic Lateral Sclerosis (ALS), Spinal Bulbar Muscular Atrophy (SBMA), and Spinal Muscular Atrophy (SMA) are motor neuron diseases (MNDs) characterised by progressive motor neuron degeneration, weakness and muscular atrophy. Lipid dysregulation is well recognised in each of these conditions and occurs prior to neurodegeneration. Several lipid markers have been shown to predict prognosis in ALS. Sphingolipids are complex lipids enriched in the central nervous system and are integral to key cellular functions including membrane stability and signalling pathways, as well as being mediators of neuroinflammation and neurodegeneration. 
  • 1.5K
  • 04 Oct 2022
Topic Review
Exclusion of the Null Hypothesis
In inferential statistics, the null hypothesis (often denoted H0) is a default hypothesis that a quantity to be measured is zero (null). Typically, the quantity to be measured is the difference between two situations, for instance to try to determine if there is a positive proof that an effect has occurred or that samples derive from different batches. The null hypothesis is effectively stating that a quantity (of interest) is larger or equal to zero AND smaller or equal to zero. If either requirement can be positively overturned, the null hypothesis is "excluded from the realm of possibilities". The null hypothesis is generally assumed to remain possibly true. Multiple analyses can be performed to show how the hypothesis should be either: rejected or excluded e.g. having high confidence level, thus demonstrating a statistically significant difference. This is demonstrated by showing that zero is outside of the specified confidence interval of the measurement on either side, typically within the real numbers. Failure to exclude the null hypothesis (with any confidence) does logically NOT confirm or support the (unprovable) null hypothesis. (When you have not proven something is e.g. bigger than x, it does not necessarily mean you have made it plausible that it is smaller or equal than x; alternatively you may just have done a lousy measurement with low accuracy. Confirming the null hypothesis two-sided would amount to positively proving it is bigger or equal than 0 AND to positively proving it is smaller or equal than 0; this is something for which you need infinite accuracy as well as exactly zero effect neither of which normally are realistic. Also measurements will never indicate a non-zero probability of exactly zero difference.) So failure of an exclusion of a null hypothesis amounts to a "don't know" at the specified confidence level; it does not immediately imply null somehow, as the data may already show a (less strong) indication for a non-null. The used confidence level does absolutely certainly not correspond to the likelihood of null at failing to exclude; in fact in this case a high used confidence level expands the still plausible range. A non-null hypothesis can have the following meanings, depending on the author a) a value other than zero is used, b) some margin other than zero is used and c) the "alternative" hypothesis. Testing (excluding or failing to exclude) the null hypothesis provides evidence that there are (or are not) statistically sufficient grounds to believe there is a relationship between two phenomena (e.g., that a potential treatment has a non-zero effect, either way). Testing the null hypothesis is a central task in statistical hypothesis testing in the modern practice of science. There are precise criteria for excluding or not excluding a null hypothesis at a certain confidence level. The confidence level should indicate the likelihood that much more and better data would still be able to exclude the null hypothesis on the same side. The concept of a null hypothesis is used differently in two approaches to statistical inference. In the significance testing approach of Ronald Fisher, a null hypothesis is rejected if the observed data is significantly unlikely to have occurred if the null hypothesis were true. In this case, the null hypothesis is rejected and an alternative hypothesis is accepted in its place. If the data is consistent with the null hypothesis statistically possibly true, then the null hypothesis is not rejected. In neither case is the null hypothesis or its alternative proven; with better or more data, the null may still be rejected. This is analogous to the legal principle of presumption of innocence, in which a suspect or defendant is assumed to be innocent (null is not rejected) until proven guilty (null is rejected) beyond a reasonable doubt (to a statistically significant degree). In the hypothesis testing approach of Jerzy Neyman and Egon Pearson, a null hypothesis is contrasted with an alternative hypothesis, and the two hypotheses are distinguished on the basis of data, with certain error rates. It is used in formulating answers in research. Statistical inference can be done without a null hypothesis, by specifying a statistical model corresponding to each candidate hypothesis, and by using model selection techniques to choose the most appropriate model. (The most common selection techniques are based on either Akaike information criterion or Bayes factor).
  • 1.5K
  • 17 Oct 2022
Topic Review
Food Bio-Based Packaging
Recently, academic research and industries have gained awareness about the economic, environmental, and social impacts of conventional plastic packaging and its disposal. This consciousness has oriented efforts towards more sustainable materials such as biopolymers, paving the way for the “green era” of food packaging.
  • 1.5K
  • 27 Oct 2022
Topic Review
Stress Memory and Inheritance of Drought Tolerance
Plants respond to drought stress by producing abscisic acid, a chemical messenger that regulates gene expression and thereby expedites various physiological and cellular processes including the stomatal operation to mitigate stress and promote tolerance. To trigger or suppress gene transcription under drought stress conditions, the surrounding chromatin architecture must be converted between a repressive and active state by epigenetic remodeling, which is achieved by the dynamic interplay among DNA methylation, histone modifications, loop formation, and non-coding RNA generation. Plants can memorize chromatin status under drought conditions to enable them to deal with recurrent stress. Furthermore, drought tolerance acquired during plant growth can be transmitted to the next generation. The epigenetically modified chromatin architectures of memory genes under stressful conditions can be transmitted to newly developed cells by mitotic cell division, and to germline cells of offspring by overcoming the restraints on meiosis.
  • 1.5K
  • 15 Nov 2022
Biography
James Spilker
James Julius Spilker Jr. (August 4, 1933) is an American engineer and a Consulting Professor in the Aeronautics and Astronautics Department at Stanford University. He was one of the principle architects of the Global Positioning System (GPS), and founder of the space communications company Stanford Telecommunications and is currently executive chairman of AOSense Inc., Sunnyvale, CA. James Spilk
  • 1.5K
  • 20 Dec 2022
Topic Review
Salt-Tolerant Plants for Cancer Prevention and Treatment
Halophytes and xerophytes, plants with adequate tolerance to high salinity with strong ability to survive in drought ecosystem, have been recognized for their nutritional and medicinal values owing to their comparatively higher productions of secondary metabolites, primarily the phenolics, and the flavonoids, as compared to the normal vegetation in other climatic regions. Given the consistent increases in desertification around the world, which are associated with increasing salinity, high temperature, and water scarcity, the survival of halophytes due to their secondary metabolic contents has prioritized these plant species, which have now become increasingly important for environmental protection, land reclamation, and food and animal-feed security, with their primary utility in traditional societies as sources of drugs. On the medicinal herbs front, because the fight against cancer is still ongoing, there is an urgent need for development of more efficient, safe, and novel chemotherapeutic agents, than those currently available.
  • 1.5K
  • 16 Mar 2023
Topic Review
Properties of Bio-Crude Oil
The bio-crude oil, a dark brown viscous liquid, comprises a mixture of light hydrocarbons and oxygenated compounds, and remarkably, it contains a high liquid content, constituting up to 75 wt%, while generating gas and char as by-products, albeit in lower yields of about 12 wt% and 13 wt%, respectively.
  • 1.5K
  • 13 Nov 2023
Topic Review
Compensation of Pressure Sensor Drifts
Pressure sensor chips embodied in very tiny packages are deployed in a wide range of advanced applications. Examples of them range from industrial to altitude location services. They are also becoming increasingly pervasive in many other fields, ranging from industrial to military to consumer. However, these sensors, which are very cheap to manufacture in silicon, are strongly affected by thermal, mechanical and environmental stresses, which ultimately affect their measurement accuracy in the form of variations in gain, hysteresis, and nonlinear responses. To compensate induced drift in measurements, several neural networks were devised and be applied to stresses caused by two thermal cycles: 260 C for 10-40 seconds (JEDEC soldering procedure) and 100 C for two hours. These models were characterized in accuracy and deployability on tiny embedded devices and improved accuracy was observed.
  • 1.5K
  • 08 Dec 2023
Topic Review
Misconfiguration in Firewalls and Network Access Controls
Firewalls and network access controls play important roles in security control and protection. Those firewalls may create an incorrect sense or state of protection if they are improperly configured. One of the major configuration problems in firewalls is related to misconfiguration in the access control rules added to the firewall that will control network traffic. The three most common misconfigurations are shadowing, correlation and redundancy.
  • 1.5K
  • 24 Nov 2021
Topic Review
Effect of the Mediator System on Laccase Catalysis
Laccase belongs to the superfamily of multicopper oxidases and has been widely investigated in recent decades. Due to its mild and efficient oxidation of substrates, laccase has been successfully applied in organic catalytic synthesis, the degradation of harmful substances, and other green catalytic fields. Adding a mediator not only effectively improves the reaction efficiency of laccase but also expands the scope of the substrate.
  • 1.5K
  • 08 May 2023
Topic Review
In Vitro Models of the Blood–Cerebrospinal Fluid Barrier
The blood–cerebrospinal fluid (CSF) barrier (BCSFB), an under-studied brain barrier site compared to the blood–brain barrier (BBB), can be considered a potential therapeutic target to improve the delivery of CNS therapeutics and provide brain protection measures. Therefore, leveraging robust and authentic in vitro models of the BCSFB can diminish the time and effort spent on unproductive or redundant development activities by a preliminary assessment of the desired physiochemical behavior of an agent toward this barrier.
  • 1.5K
  • 30 Sep 2022
Topic Review
Impulse Control Disorder
Impulse-control disorder (ICD) is a class of psychiatric disorders characterized by impulsivity – failure to resist a temptation, an urge, an impulse, or the inability to not speak on a thought. Many psychiatric disorders feature impulsivity, including substance-related disorders, behavioral addictions, attention deficit hyperactivity disorder, antisocial personality disorder, borderline personality disorder, conduct disorder and some mood disorders. The fifth edition of the American Psychiatric Association's Diagnostic and statistical manual of mental disorders (DSM-5) that was published in 2013 includes a new chapter (not in DSM-IV-TR) on Disruptive, Impulse-Control, and Conduct Disorders covering disorders "characterized by problems in emotional and behavioral self-control".Five behavioral stages characterize impulsivity: an impulse, growing tension, pleasure on acting, relief from the urge and finally guilt (which may or may not arise).
  • 1.5K
  • 01 Nov 2022
Topic Review
Sclerostin in Physiological Calcification
Sclerostin, a 22-kDa glycoprotein that is mainly secreted by the osteocytes, is a soluble inhibitor of canonical Wnt signaling. This canonical Wnt signaling pathway, in addition to its function during embryogenesis, also plays a crucial role in adult tissue homeostasis by regulating the maintenance and differentiation of stem cells. In particular, this signaling cascade also exerts an important regulatory pathway in the differentiation of mesenchymal stem cells towards the osteoblast-lineage. Since sclerostin is an inhibitor of this signaling pathway, increased sclerostin concentrations will lead to an increased bone resorption and decreased bone formation. The cellular and molecular actions that are involved in this process, will be discussed in this review.
  • 1.5K
  • 29 Oct 2020
Topic Review
Efficient Structural Design with ANNs
Artificial Neural Networks (ANNs) are showing their potential as structural design tools. ANNs are applied to design a dry precast concrete connection. They can be easily and effectively adapted to different connection parameters, being possible to use them in both precast or cast in situ concrete connection design.
  • 1.5K
  • 27 Oct 2020
Topic Review
Pelvic Girdle Pain
Pelvic girdle pain (PGP) refers specifically to musculoskeletal pain localised to the pelvic ring and can be present at its anterior and/or posterior aspects. Causes such as trauma, infection and pregnancy have been well-established, while patients with hypermobile joints are at greater risk of developing PGP.
  • 1.5K
  • 11 Oct 2021
Topic Review
Wavefront shaping concepts in OCT
Optical coherence tomography (OCT) enables three-dimensional imaging with resolution on the micrometer scale. The technique relies on the time-of-flight gated detection of light scattered from a sample and has received enormous interest in applications as versatile as non-destructive testing, metrology and non-invasive medical diagnostics. However, in strongly scattering media such as biological tissue, the penetration depth and imaging resolution are limited. Combining OCT imaging with wavefront shaping approaches significantly leverages the capabilities of the technique by controlling the scattered light field through manipulation of the field incident on the sample.
  • 1.5K
  • 24 Dec 2020
Topic Review
FENIB
Familial encephalopathy with neuroserpin inclusion bodies (FENIB) is a disorder that causes progressive dysfunction of the brain (encephalopathy).
  • 1.5K
  • 04 Jan 2021
  • Page
  • of
  • 2800
Featured Entry Collections
>>

Featured Reprints

>>
Encyclopedia of Digital Society, Industry 5.0 and Smart City
Encyclopedia of Engineering
Encyclopedia of Social Sciences
Encyclopedia of Medieval Royal Iconography
Academic Video Service
Feedback