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Topic Review
List of Railway Electrification Systems
This is a list of the power supply systems that are, or have been, used for tramway and railway electrification systems. Note that the voltages are nominal and vary depending on load and distance from the substation. Many modern trams and trains use on-board solid-state electronics to convert these supplies to run three-phase AC induction motors. Tram electrification systems are listed here.
  • 4.1K
  • 27 Nov 2022
Topic Review
The Tyrrhenian Sea Circulation
Knowledge about marine circulation and its variability is a basic requirement for the correct management of activities aimed at exploiting marine resources and for the prevention and eventual mitigation of the risks involved. The activities of the Marine Hazard Project, to which this special number of Sustainability is dedicated, focus on geothermal resources connected with some submerged volcanic systems located in the Tyrrhenian Sea. This sea hosts delicate coastal and marine ecosystems, and is characterized by rich dynamics, both driven by the interaction of the local forcing with the complex morphology and bathymetry of the basin, and by exchanges with adjacent sub-basins which take place at all depths. 
  • 4.1K
  • 17 Jun 2021
Topic Review
Incompressible Navier Stokes Equations
A closely related problem to The Clay Math Institute "Navier-Stokes, breakdown of smooth solutions here on an arbitrary cube subset of three dimensional space with periodic boundary conditions is examined. The incompressible Navier-Stokes Equations are presented in a new and conventionally different way here, by naturally reducing them to an operator form which is then further analyzed. It is shown that a reduction to a general 2D N-S system decoupled from a 1D non-linear partial differential equation is possible to obtain. This is executed using integration over n-dimensional compact intervals which allows decoupling. Here we extract the measure-zero points in the domain where singularities may occur and are left with a pde that exhibits finite time singularity. The operator form is considered in a physical geometric vorticity case, and a more general case. In the general case, the solution is revealed to have smooth solutions which exhibit finite-time blowup on a fine measure zero set and using the Gagliardo-Nirenberg inequalities it is shown that for any non zero measure set in the form of cube subset of 3D there is finite time blowup.
  • 4.1K
  • 10 Dec 2020
Topic Review
Antibacterial Designs for Implantable Medical Devices
The uses of implantable medical devices are safer and more common since sterilization methods and techniques were established a century ago; however, device-associated infections (DAIs) are still frequent and becoming a leading complication as the number of medical device implantations keeps increasing.
  • 4.1K
  • 01 Aug 2022
Topic Review
Space and Upper Atmosphere Research Commission
Established in its modern form on 16 September 1961 by an executive order of President of Pakistan, it is headquartered in Karachi, Sindh Province of Pakistan. Part of the Strategic Plans Division (SPD) of Pakistan Armed Forces, which is currently headquartered at the Chakalala Military District under the control of the Pakistan Air Force ; the space programmes recorded number of pioneering accomplishments in space flight during the initial years of its establishment. The country's first satellite, Badr-I, was built by the SUPARCO and launched from the Xichang Satellite Launch Center, China on July 16, 1990. However, during the meantime, the space programme suffered many setbacks, difficulties, and problems that partly slowed the progress of the space programme. The bureaucratic influence and politicization further lagged the space programme and many projects were cancelled by the superior authorities. Over the years, SUPARCO expanded and it now has several installations all over the country. It has multi-lateral and bilateral international agreements. SUPARCO has been quite dormant in recent years and also have failed to make any breakthroughs. SUPARCO's science and research is mainly focused and concentrated on understanding of the Solar system, Space weather, astrophysics, astronomical observation, climatic studies, space and telemedicine, remote sensing and the Earth observation.
  • 4.1K
  • 02 Nov 2022
Topic Review
Solid Oxide Electrolysis Cells and SOFCs Components
Solid oxide electrolysis cells (SOECs) and solid oxide fuel cells (SOFCs) are the leading high-temperature devices to realize the global “Hydrogen Economy”. These devices are inherently multi-material (ceramic and cermets). They have multi-scale, multilayer configurations (a few microns to hundreds of microns) and different morphology (porosity and densification) requirements for each layer. Adjacent layers should exhibit chemical and thermal compatibility and high-temperature mechanical stability. 
  • 4.1K
  • 20 Oct 2022
Topic Review
Ketamine and Driving, Cognitive, and Motor Ability
Ketamine is a medication that has many medical purposes but also has been used illicitly by people for its dissociative properties. While driving under the influence of drugs, drivers are more likely to be involved in and cause more accidents than drivers who do not drive under the influence.  A study with ketamine and a ketamine-like medication, rapasitnel, showed that those who were given ketamine experienced more sleepiness and had decreased self-reported motivation and confidence in their driving abilities. Moreover, there seem to be significant differences in the acute versus persistent effects of ketamine, as well as the anesthetic versus subanesthetic doses, both in terms of effects and outcomes. These divergent effects complicate the clinical uses of ketamine, specifically involving driving, drowsiness, and cognitive abilities. 
  • 4.1K
  • 16 Mar 2023
Topic Review
Step-Down Partial Power DC-DC Converters
Photovoltaic (PV) systems made-up by two-stages of energy conversion are attractive from the operation point view. It is because the MPPT range is extended, due to the voltage decoupling between the PV system and the dc-link. Nevertheless, the additional conversion stage increases the volume, cost and power converter losses. Therefore, in large-scale PV systems formed by series connection of PV modules, most of commercial inverters are based on a single-stage system. The concept of partial power converters (PPC), previously implemented as a step-up stage, has not fully covered all PV applications. In this work, a PPC performing step-down operation is proposed and analyzed for a PV string application. This concept is actually interesting from the industry point of view, since with the new isolation standards of PV modules reaching 1500V, larger strings are currently starting to become popular. Since grid connection remains below 690V, larger strings impose more demanding operation for single-stage central inverters (required to operate at lower modulation indexes and demand higher blocking voltage devices). 
  • 4.1K
  • 01 Nov 2020
Topic Review
Homelessness
Homelessness is the circumstance when people are without a permanent dwelling, such as a house or apartment. People who are homeless are most often unable to acquire and maintain regular, safe, secure and adequate housing. The legal definition of homeless varies from country to country, or among different jurisdictions in the same country or region. The term homeless may also include people whose primary night-time residence is in a homeless shelter, a domestic violence shelter, long-term residence in a motel, a vehicle, squatting, cardboard boxes, a tent city, tarpaulins, shanty town structures made of discarded building materials or other ad hoc housing situations. According to the UK homelessness charity Crisis, a home is not just a physical space: it also provides roots, identity, security, a sense of belonging and a place of emotional wellbeing. United States government homeless enumeration studies also include people who sleep in a public or private place not designed for use as a regular sleeping accommodation for human beings. There are a number of organizations who provide help for the homeless. In 2005, an estimated 100 million (1 in 65 at the time) people worldwide were homeless and as many as 1 billion people live as squatters, refugees or in temporary shelter, all lacking adequate housing. In Western countries, the majority of homeless are men (50–80%), with single males particularly overrepresented. However, current data suggests similar rates of homeless males and females. Most countries provide a variety of services to assist homeless people. These services often provide food, shelter (beds) and clothing and may be organized and run by community organizations (often with the help of volunteers) or by government departments or agencies. These programs may be supported by the government, charities, churches and individual donors. Many cities also have street newspapers, which are publications designed to provide employment opportunity to homeless people. While some homeless have jobs, some must seek other methods to make a living. Begging or panhandling is one option, but is becoming increasingly illegal in many cities. People who are homeless may have additional conditions, such as physical or mental health issues or substance addiction; these issues make resolving homelessness a challenging policy issue. Homeless people, and homeless organizations, are sometimes accused or convicted of fraudulent behaviour. Criminals are also known to exploit homeless people, ranging from identity theft to tax and welfare scams. These incidents often lead to negative connotations on the homeless as a group.
  • 4.1K
  • 30 Oct 2022
Topic Review
NdFeB Permanent Magnet Uses
Rare earth element (REE) permanent magnets (NdFeB) are a critical element in a vast and growing number of industrial applications. In consumer electronics, a broad category encompassing computer, CD, and DVD hard drives, in addition to the ubiquitous cell phones, the nominal NdFeB magnet content may be small, but the global market share for this sector accounts for almost 30% of NdFeB demand, due to a large and continually increasing consumer base. It is estimated that wind turbines that primarily employ permanent magnets will add roughly 110 GW annually of on- and off-shore capability over the next few years. Electric vehicles (EVs) and E-bicycles (EBs) equipped with permanent magnet motors comprise the transportation contribution. Permanent magnet motors have garnered nearly 100% of the market share among EV manufacturers worldwide. Industrial, professional service, and personal robots, most using permanent magnets, are also included in the projected global need for rare earths, particularly Nd and Dy.
  • 4.1K
  • 16 Oct 2023
Topic Review
Intersubjectivity
Intersubjectivity refers to the shared understanding and mutual agreement between individuals regarding their subjective experiences, perceptions, and interpretations of the world. It involves the recognition and validation of each other's perspectives, allowing for meaningful communication, cooperation, and collaboration based on common understanding and empathy. Intersubjectivity is essential for social interaction, interpersonal relationships, and the construction of shared meanings within society.
  • 4.1K
  • 02 Feb 2024
Topic Review
Iris (Anatomy)
In humans and most mammals and birds, the iris (plural: irides or irises) is a thin, circular structure in the eye, responsible for controlling the diameter and size of the pupil and thus the amount of light reaching the retina. Eye color is defined by that of the iris. In optical terms, the pupil is the eye's aperture, while the iris is the diaphragm.
  • 4.1K
  • 11 Oct 2022
Topic Review
Physical Activity Patterns
Although “physical activity pattern” (PAP) is a widely used expression, its precise meaning remains vague. Indeed, PAP is sometimes used to describe physical activity (PA) levels/intensities, however the term is also applied to express how PA averages differ among group,  between different days (i.e., week and weekend days), across seasons (e.g., summer, winter), and between school and vacation time. A lack of a formal definition for PAP has not prevented researchers from using a vast array of instruments to measure PA (accelerometers, pedometers, questionnaires, direct observations, and heart rate monitors) in an attempt to capture PAP. Discrepancies also exist in how PAP has been expressed with researchers using daily mean PA, heart rate frequency, number of daily steps, time engaged in certain types of activity, and/or engagement in sports activities. Researchers have also used numerous statistical procedures in their attempts to capture PAP. Notwithstanding this diversity, we suggest that PAP should be used to jointly capture similarities/dissimilarities as well as stabilities/changes in children’s PA at an intra-personal level. PAP should be used to best describe individual streams of behaviours, and not exclusively PA levels/intensities. A formal and clear definition of PAP would support important, systematic, and coherent lines of empirical enquiry.
  • 4.1K
  • 24 Apr 2021
Topic Review
Synthetic Biology and Its Application in Bioremediation
Synthetic biology is a scientific field based on biology and engineering principles, with the purpose of redesigning and restructuring microorganisms to optimize or create new biological systems with enhanced features. Developing innovative, fast, safe, and cost-effective techniques for elimination of pollutants is of great importance. For this reason, the use of this discipline offers improvement of bioremediation processes. 
  • 4.1K
  • 15 Apr 2022
Topic Review
Point-Of-Care or Point-Of-Need Diagnostic Tests
In the recent years, the progress of international trade and travel has led to an increased risk of emerging infections. Around 75 percent of the pathogens causing these infections are of animal origin. Point-of-care tests (POCT) and point-of-need tests (PONT) have been established in order to directly provide accurate and rapid diagnostics at field level, the patient bed-side or at the site of outbreaks. These assays can help physicians and decision makers to take the right action without delay. Typically, POCT and PONT rely on genomic identification of pathogens or track their immunological fingerprint. Recently, protocols for metagenomic diagnostics in the field have been developed.
  • 4.1K
  • 20 Apr 2021
Topic Review
Natural Jute Fibers
The increasing trend of the use of synthetic products may result in an increased level of pollution affecting both the environment and living organisms. Therefore, from the sustainability point of view, natural, renewable and biodegradable materials are urgently needed to replace environmentally harmful synthetic materials. Jute, one of the natural fibers, plays a vital role in developing composite materials that showed potential in a variety of applications such as household, automotive and medical appliances.
  • 4.1K
  • 06 Apr 2022
Topic Review
Organic Matter Sources in Lake Sediments
Sedimentary organic matter is an important component of the metabolism of a lake’s ecosystem, and it is generally derived from both the watershed and the primary productivity of a lake. Understanding the sources of organic matter in lakes and lake trophic status is important when evaluating the quality of lake ecosystems.
  • 4.1K
  • 01 Mar 2023
Topic Review
Wire
Wire is an encrypted communication and collaboration app created by Wire Swiss. It is available for iOS, Android, Windows, macOS, Linux, and web browsers such as Firefox. Wire offers a collaboration suite featuring messenger, voice calls, video calls, conference calls, file-sharing, and external collaboration – all protected by a secure end-to-end-encryption. Wire offers three solutions built on its security technology: Wire Pro – which offers Wire's collaboration feature for businesses, Wire Enterprise – includes Wire Pro capabilities with added features for large-scale or regulated organizations, and Wire Red – the on-demand crisis collaboration suite. They also offer Wire Personal, which is a secure messaging app for personal use.
  • 4.1K
  • 04 Nov 2022
Biography
Wilhelm Conrad Röntgen
Wilhelm Conrad Röntgen (1845–1923) was a German physicist best known for his discovery of X-rays in 1895, a groundbreaking advancement in medical imaging and physics that revolutionized both science and medicine. He was the first recipient of the Nobel Prize in Physics in 1901 for this discovery. Röntgen’s contributions laid the foundation for diagnostic radiology and profoundly influenced
  • 4.1K
  • 28 Aug 2025
Topic Review
Cutibacterium acnes
Cutibacterium acnes is a member of the skin microbiota found predominantly in regions rich in sebaceous glands. It is involved in maintaining healthy skin and has long been considered a commensal bacterium. Its involvement in various infections has led to its emergence as an opportunist pathogen. Interactions between C. acnes and the human host, including the human skin microbiota, promote the selection of C. acnes strains capable of producing several virulence factors that increase inflammatory capability. This pathogenic property may be related to many infectious mechanisms, such as an ability to form biofilms and the expression of putative virulence factors capable of triggering host immune responses or enabling C. acnes to adapt to its environment. During the past decade, many studies have identified and characterized several putative virulence factors potentially involved in the pathogenicity of this bacterium. These virulence factors are involved in bacterial attachment to target cells, polysaccharide-based biofilm synthesis, molecular structures mediating inflammation, and the enzymatic degradation of host tissues. C. acnes, like other skin-associated bacteria, can colonize various ecological niches other than skin. It produces several proteins or glycoproteins that could be considered to be active virulence factors, enabling the bacterium to adapt to the lipophilic environment of the pilosebaceous unit of the skin, but also to the various organs it colonizes. 
  • 4.1K
  • 22 Sep 2021
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