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Thalassocnus
Thalassocnus is an extinct genus of semiaquatic ground sloths from the Miocene and Pliocene of the Pacific South American coast. It is monotypic within the subfamily Thalassocninae. The five species—T. antiquus, T. natans, T. littoralis, T. carolomartini, and T. yuacensis—represent a chronospecies, a population gradually adapting to marine life in one direct lineage. They are the only known aquatic sloths. They have been found in the Pisco Formation of Peru and the Bahía Inglesa, Coquimbo, and Horcón formations of Chile. Thalassocninae has been placed in both the families Megatheriidae and Nothrotheriidae. Thalassocnus evolved several marine adaptations over the course of 4 million years, such as dense and heavy bones to counteract buoyancy, the internal nostrils migrating farther into the head to help with breathing while completely submerged, the snout becoming wider and more elongated to consume aquatic plants better, and the head angling farther and farther downwards to aid in bottom feeding. The long tail was probably used for diving and balance similarly to the modern day beaver (Castor spp.) and platypus (Ornithorhynchus anatinus). Thalassocnus probably walked across the seafloor and dug up food with its claws. They probably could not do high-powered swimming, relying on paddling if necessary. Early Thalassocnus were probably generalist grazers eating seaweed and seagrasses close to shore, whereas later species specialized on seagrasses farther off the coast. They were probably preyed upon by sharks and macroraptorial sperm whales such as Acrophyseter. Thalassocnus were found in formations with large marine mammal and shark assemblages.
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  • 27 Sep 2022
Topic Review
Central Line (Geometry)
In geometry, central lines are certain special straight lines that lie in the plane of a triangle. The special property that distinguishes a straight line as a central line is manifested via the equation of the line in trilinear coordinates. This special property is related to the concept of triangle center also. The concept of a central line was introduced by Clark Kimberling in a paper published in 1994.
  • 2.0K
  • 27 Sep 2022
Topic Review
Six Rays Model
Six-rays model is applied in an urban or indoor environment where a radio signal transmitted will encounter some objects that produce reflected, refracted or scattered copies of the transmitted signal. These are called multipath signal components, they are attenuated, delayed and shifted from the original signal (LOS) due to a finite number of reflectors with known location and dielectric properties, LOS and multipath signal are summed at the receiver. This model approach the propagation of electromagnetic waves by representing wavefront as simple particles. Thus reflection, refraction and scattering effects are approximated using simple geometric equation instead Maxwell's wave equations. The simplest model is two-rays which predicts signal variation resulting from a ground reflection interfering with the loss path. This model is applicable in isolated areas with some reflectors, such as rural roads or hallway. The above two-rays approach can easily be extended to add as many rays as required. We may add rays bouncing off each side of a street in an urban corridor, leading to a six-rays model. The deduction of the six-rays model is presented below.
  • 680
  • 27 Sep 2022
Topic Review
Interferon Gamma
Interferon gamma (IFN-γ) is a dimerized soluble cytokine that is the only member of the type II class of interferons. The existence of this interferon, which early in its history was known as immune interferon, was described by E. F. Wheelock as a product of human leukocytes stimulated with phytohemagglutinin, and by others as a product of antigen-stimulated lymphocytes. It was also shown to be produced in human lymphocytes. or tuberculin-sensitized mouse peritoneal lymphocytes challenged with Mantoux test (PPD); the resulting supernatants were shown to inhibit growth of vesicular stomatitis virus. Those reports also contained the basic observation underlying the now widely employed IFN-γ release assay used to test for tuberculosis. In humans, the IFN-γ protein is encoded by the IFNG gene.
  • 2.4K
  • 28 Apr 2023
Topic Review
Power Soccer (Browser-based Game)
Power Soccer, also known as Power Challenge and PS, was a massively multiplayer online browser-based sports game, developed by the Swedish developer Power Challenge, the same company that develops ManagerZone (but PS focuses in the sports gameplay instead of management simulation). This game was a browser-based soccer simulator in which users could create a team and play against other users from all around the globe. Additional benefits were offered to those that purchased the Club Membership. Following a decline in interest from users in the game, it was announced that on May 16, 2016 Power Soccer would come to an end, encouraging users to join their sister game ManagerZone. The announcement was made months before the closure date, which led to many posts in the forums where some users even wanted to donate to keep the game afloat but to no avail, and in the early hours of May 16, 2016, the game closed.
  • 1.1K
  • 27 Sep 2022
Topic Review
Nielsen Ratings
Nielsen TV ratings (commonly referred to as "Nielsen ratings") are the audience measurement systems operated by Nielsen Media Research that seek to determine the audience size and composition of television programming in the United States using a rating system. Nielsen Media Research was founded by Arthur C. Nielsen, a market analyst who started his career in the 1920s with marketing research and performance analysis. The company expanded into radio market analysis in the late 1930s, culminating in the Nielsen Radio Index in 1942, which was meant to provide statistics as to the markets of radio shows. The first Nielsen ratings for radio programs were released the first week of December 1947. They measured the top 20 programs in four areas: total audience, average audience, cumulative audience, and homes per dollar spent for time and talent. In 1950, Nielsen moved to television, developing a ratings system using the methods he and his company had developed for radio. That method became the primary source of audience measurement information in the US television industry.
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  • 29 Sep 2022
Topic Review
Substrate Integrated Waveguide
A Substrate integrated waveguide (SIW) (also known as post-wall waveguide or laminated waveguide) is a synthetic rectangular electromagnetic waveguide formed in a dielectric substrate by densely arraying metallized posts or via-holes which connect the upper and lower metal plates of the substrate. The waveguide can be easily fabricated with low-cost mass-production using through-hole techniques where the post walls consists of via fences. SIW is known to have similar guided wave and mode characteristics to conventional rectangular waveguide with equivalent guide wavelength. Since the emergence of new communication technologies in the 1990s, there has been an increasing need for high-performance millimeter-wave systems. These need to be reliable, low-cost, compact, and compatible with high-frequencies. Unfortunately, above 10 GHz, the well known microstrip and coplanar lines technologies cannot be used because they have high insertion and radiation losses at these frequencies. The rectangular waveguide topology can overcome these issues as it offers an excellent immunity against radiation losses and presents low insertion losses. But in their classical form, rectangular waveguide is not compatible with the miniaturization required by modern applications. The concept of SIW was developed in the early 2000s by Ke Wu to reconcile those requirements. The authors presented a platform for integrating all the components of a microwave circuit inside a single substrate, with a rectangular cross-section. Using a single substrate guarantees a limited volume and a simplicity of manufacture, while the rectangular cross-section of the line provides the advantages of the waveguide topology in terms of losses.
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  • 27 Sep 2022
Topic Review
Chromosome 16 Open Reading Frame 13
An Error has occurred retrieving Wikidata item for infobox Chromosome 16 open reading frame 13, also called C16orf13, is a protein-coding gene of unknown function, also known as JFP2. Though the function of this gene is unknown, various data have revealed that it is expressed at high levels in various cancerous tissues. Underexpression of this gene has also been linked to disease consequences in humans.
  • 929
  • 27 Sep 2022
Topic Review
Wild Animal Suffering
Wild animal suffering is the suffering experienced by nonhuman animals living outside of direct human control, due to harms such as disease, injury, parasitism, starvation and malnutrition, dehydration, weather conditions, natural disasters, and killings by other animals, as well as psychological stress. Some estimates indicate that the vast majority of individual animals in existence live in the wild. A vast amount of natural suffering has been described as an unavoidable consequence of Darwinian evolution and the pervasiveness of reproductive strategies which favor producing large numbers of offspring, with a low amount of parental care and of which only a small number survive to adulthood, the rest dying in painful ways, has led some to argue that suffering dominates happiness in nature. The topic has historically been discussed in the context of the philosophy of religion as an instance of the problem of evil. More recently, starting in the 19th-century, a number of writers have considered the suspected scope of the problem from a secular standpoint as a general moral issue, one that humans might be able to take actions toward preventing. There is considerable disagreement around this latter point as many believe that human interventions in nature, for this reason, should not take place because of practicality, valuing ecological preservation over the well-being and interests of individual animals, considering any obligation to reduce wild animal suffering implied by animal rights to be absurd, or viewing nature as an idyllic place where happiness is widespread. Some have argued that such interventions would be an example of human hubris, or playing God and use examples of how human interventions, for other reasons, have unintentionally caused harm. Others, including animal rights writers, have defended variants of a laissez-faire position, which argues that humans should not harm wild animals, but that humans should not intervene to reduce natural harms that they experience. Advocates of such interventions argue that animal rights and welfare positions imply an obligation to help animals suffering in the wild due to natural processes. Some have asserted that refusing to help animals in situations where humans would consider it wrong not to help humans is an example of speciesism. Others argue that humans intervene in nature constantly—sometimes in very substantial ways—for their own interests and to further environmentalist goals. Human responsibility for enhancing existing natural harms has also been cited as a reason for intervention. Some advocates argue that humans already successfully help animals in the wild, such as vaccinating and healing injured and sick animals, rescuing animals in fires and other natural disasters, feeding hungry animals, providing thirsty animals with water, and caring for orphaned animals. nThey also assert that although wide-scale interventions may not be possible with our current level of understanding, they could become feasible in the future with improved knowledge and technologies. For these reasons, they claim it is important to raise awareness about the issue of wild animal suffering, spread the idea that humans should help animals suffering in these situations and encourage research into effective measures which can be taken in the future to reduce the suffering of these individuals, without causing greater harms.
  • 3.4K
  • 29 Sep 2022
Topic Review
F9R Dev2
Grasshopper and the Falcon 9 Reusable Development Vehicles (F9R Dev) were experimental flight test reusable rockets that performed vertical takeoffs and landings. The project was privately funded by SpaceX, with no funds provided by any government until later on. Two prototypes were built, and both were launched from the ground. Grasshopper was announced in 2011 and began low-altitude, low-velocity hover/landing testing in 2012. The initial Grasshopper test vehicle was 106 ft (32 m) tall and made eight successful test flights in 2012 and 2013 before being retired. A second Grasshopper-class prototype was the larger and more capable Falcon 9 Reusable Development Vehicle (F9R Dev, also known as F9R Dev1) based on the Falcon 9 v1.1 launch vehicle. It was tested at higher altitudes and was capable of much higher velocity but was never tested at high velocity. The F9R Dev1 vehicle was built in 2013–2014 and made its first low-altitude flight test on 17 April 2014; it was lost during a three-engine test at the McGregor test site on 22 August 2014, which ended the low-velocity test program. Further expansion of the flight test envelope for the reusable rocket was moved to descending Falcon 9 boosters that had been used on orbital flight trajectories on commercial orbital flights of the Falcon 9. The Grasshopper and F9R Dev tests were fundamental to the development of the reusable Falcon 9 and Falcon Heavy rockets, which require vertical landings of the near-empty Falcon 9 and Falcon Heavy first-stage booster tanks and engine assemblies. The Grasshopper and the F9R Dev tests led into a series of high-altitude, high-speed controlled-descent tests of post-mission (spent) Falcon 9 booster stages that accompanied the commercial Falcon 9 missions since September 2013. The latter eventually resulted in the first successful booster landing on 21 December 2015.
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  • 28 Sep 2022
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