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Topic Review
Sex Organ
A sex organ (or reproductive organ) is any part of an animal's body that is involved in sexual reproduction. The reproductive organs together constitute the reproductive system. The testis in the male, and the ovary in the female, are called the primary sex organs. All others are called secondary sex organs, divided between the external sex organs—the genitals or genitalia, visible at birth in both sexes—and the internal sex organs. Mosses, ferns, and some similar plants have gametangia for reproductive organs, which are part of the gametophyte. The flowers of flowering plants produce pollen and egg cells, but the sex organs themselves are inside the gametophytes within the pollen and the ovule. Coniferous plants likewise produce their sexually reproductive structures within the gametophytes contained within the cones and pollen. The cones and pollen are not themselves sexual organs.
  • 3.8K
  • 04 Nov 2022
Biography
Polly Toynbee
Mary Louisa "Polly" Toynbee (/ˈtɔɪnbi/; born 27 December 1946)[1] is a British journalist and writer. She has been a columnist for The Guardian newspaper since 1998. She is a social democrat and was a candidate for the Social Democratic Party in the 1983 general election. She now broadly supports the Labour Party, although she has been critical of its current left-wing leader, Jeremy Corbyn
  • 3.8K
  • 30 Nov 2022
Topic Review
Sulfolobus Solfataricus
Saccharolobus solfataricus is a species of thermophilic archaeon. It was transferred from the genus Sulfolobus to the new genus Saccharolobus with the description of Saccharolobus caldissimus in 2018. It was first isolated and discovered in the Solfatara volcano (which it was subsequently named after) in 1980 by two Germans microbiologists Karl Setter and Wolfram Zillig, in Solfatara volcano (Pisciarelli-Campania, Italy). However, these organisms are not isolated to volcanoes but are found all over the world in places such as hot springs. The species grows best in temperatures around 80° Celsius, a pH level between 2 and 4, and enough sulfur for solfataricus to metabolize in order to gain energy. These conditions qualify it as an extremophile and it is specifically known as a thermoacidophile because of its preference to high temperatures and low pH levels and it is also in aerobic and heterotropic categories for its metabolic system. It usually has a spherical cell shape and it makes frequent lobes. Being an autotroph it receives energy from growing on sulfur or even a variety of organic compounds. Currently, it is the most widely studied organism that is within the Crenarchaeota branch. Solfataricus are researched for their methods of DNA replication, cell cycle, chromosomal integration, transcription, RNA processing, and translation. All the data points to the organism having a large percent of archaeal-specific genes, which showcases the differences between the three types of microbes: archaea, bacteria, and eukarya.
  • 3.8K
  • 04 Nov 2022
Topic Review
Monotremata
Monotremes (/ˈmɒnətriːmz/) are prototherian mammals of the order Monotremata. They are one of the three groups of living mammals, along with placentals (Eutheria) and marsupials (Metatheria). Monotremes are typified by structural differences in their brains, jaws, digestive tract, reproductive tract, and other body parts compared to the more common mammalian types. In addition, they lay eggs rather than bearing live young, but, like all mammals, the female monotremes nurse their young with milk. Monotremes have been considered members of Australosphenida, a clade which contains extinct mammals from the Jurassic and Cretaceous of Madagascar, South America and Australia, though this is disputed. The only surviving examples of monotremes are all indigenous to Australia and New Guinea although there is evidence that they were once more widespread, as Monotrematum is known from the Paleocene of South America. The extant monotreme species are the platypus and four species of echidnas. There is currently some debate regarding monotreme taxonomy. The name monotreme derives from the Greek words μονός (monós 'single') and τρῆμα (trêma 'hole'), referring to the cloaca.
  • 3.7K
  • 19 Oct 2022
Topic Review
Prospective Memory
Prospective memory is a form of memory that involves remembering to perform a planned action or recall a planned intention at some future point in time. Prospective memory tasks are common in daily life and range from the relatively simple to extreme life-or-death situations. Examples of simple tasks include remembering to put the toothpaste cap back on, remembering to reply to an email, or remembering to return a rented movie. Examples of highly important situations include a patient remembering to take medication or a pilot remembering to perform specific safety procedures during a flight. In contrast to prospective memory, retrospective memory involves remembering people, events, or words that have been encountered in the past. Whereas retrospective memory requires only the recall of past events, prospective memory requires the exercise of retrospective memory at a time that has not yet occurred. Prospective memory is thus considered a form of "memory of the future". Retrospective memory involves the memory of what we know, containing informational content; prospective memory focuses on when to act, rather than focusing on informational content. There is some evidence demonstrating the role of retrospective memory in the successful execution of prospective memory, but this role seems to be relatively small.
  • 3.7K
  • 30 Oct 2022
Topic Review
Poaching
Poaching has been defined as the illegal hunting or capturing of wild animals, usually associated with land use rights. According to Encyclopædia Britannica, poaching was performed by impoverished peasants for subsistence purposes and a supplement for meager diets. Poaching was as well set against the hunting privileges of nobility and territorial rulers. By contrast, stealing domestic animals (as in cattle raiding, for example) classifies as theft, not as poaching. Since the 1980s, the term "poaching" has also referred to the illegal harvesting of wild plant species. In agricultural terms, the term 'poaching' is also applied to the loss of soils or grass by the damaging action of feet of livestock which can affect availability of productive land, water pollution through increased runoff and welfare issues for cattle.
  • 3.7K
  • 24 Nov 2022
Topic Review
Collagen in Wound Healing
Collagens are the most abundant protein found throughout the body. In the healing wound, these collagens are synthesized by cells such as fibroblasts and modified into complex morphologies . The type, amount and organization of collagen changes in the healing wound and determines the tensile strength of the healed skin. Collagen III is the first to be synthesized in the early stages of wound healing and is replaced by collagen I, the dominant skin collagen. The initial random deposition of collagen during the granulation tissue formation is further enhanced by lysyl oxidase enzyme-induced covalent cross-linking. This process matures the collagen into complex structures that are reoriented for tensile strength restoration. Collagen remodeling continues for months after wound closure and the tensile strength of the repaired tissue increases to about 80–85% of normal tissue if all processes proceed without any perturbations.In the skin, the fibrillar collagens types I, III and V are the most common, followed by fibril-associated collagens type XII, XIV, XVI, and VI. The non-fibrillar collagens type IV, XVIII are found in the basement membrane of the skin
  • 3.7K
  • 23 Jun 2021
Topic Review
Bush Encroachment in Namibia
Bush encroachment is a natural phenomenon characterised by the excessive expansion of bush at the expense of other plant species, especially grasses. Bush encroachment is estimated to affect up to 45 million ha of Namibian land and has severe negative consequences on key Ecosystem services, especially agricultural productivity and groundwater recharge. Agricultural productivity in Namibia has declined by two thirds throughout the past decades, mainly due to the negative impact of bush encroachment. The phenomenon affects both commercial and communal farming in Namibia, mostly the central, eastern and north-eastern regions.
  • 3.7K
  • 23 Nov 2022
Topic Review
Mitochondrial dysfunction and Inflammatory Responses
Exaggerated oxidative stress and hyper-inflammation are essential features of oxidative/inflammatory diseases. Simultaneously, both processes may be the cause or consequence of mitochondrial dysfunction, thus establishing a vicious cycle among these three factors. However, several natural substances, including melatonin and micronutrients, may prevent or attenuate mitochondrial damage and may preserve an optimal state of health by managing the general oxidative and inflammatory status.
  • 3.6K
  • 27 Apr 2021
Topic Review
The Dog–Owner Relationship
The Cat/Dog–Owner Relationship Scale (C/DORS) is a questionnaire aimed to assess specific aspects of the pet–owner relationship. While the entire scale can be administered to both dog and cat owners, its validity and reliability have never been tested on dogs. Furthermore, validity and reliability of a scale may change depending on the respondents’ language and cultural background. Since the C/DORS was developed in English, we aimed to translate it into Italian and assess its validity and reliability on a sample of Italian dog owners. The response scale was modified to improve the variability of the owners’ responses. Overall, validity and reliability were good. The scale had the same three-factor structure (Perceived Emotional Closeness = PEC, Pet–Owner Interactions = POI, Perceived Costs = PC) reported for the original English version, although some items were removed because they did not fit the statistical model. The PEC subscale had the highest correlations with the subscales of the Lexington Attachment to Pets Scale. Finally, being a student owner was associated with higher PEC and POI scores. Conversely, owning a dog with behavioural problems was associated with lower PEC and higher PC. Owners whose dogs lived outdoors reported lower POI. Pet dog owners reported higher PEC than AAI dog owners.
  • 3.6K
  • 17 Aug 2021
Topic Review
Interference Theory
The interference theory is a theory regarding human memory. Interference occurs in learning. The notion is that memories encoded in long-term memory (LTM) are forgotten and cannot be retrieved into short-term memory (STM) because either memory interferes, or hampers, the other. There is an immense number of encoded memories within the storage of LTM. The challenge for memory retrieval is recalling the specific memory and working in the temporary workspace provided in STM. Retaining information regarding the relevant time of encoding memories into LTM influences interference strength. There are two types of interference effects: proactive and retroactive interference.
  • 3.6K
  • 10 Nov 2022
Topic Review
Applications of Lysozyme
Lysozyme (or muramidase or N-acetylmuramic acid hydrolase E.C. 3.2.1.17) is a protein that exerts its enzymatic activity through the hydrolysis of the β-1,4-glycosidic bonds between N-acetylmuramic acid (NAM) and N-acetylglucosamide (NAG) in the polysaccharide backbone of the peptidoglycans of the Gram-positive bacterial cell wall. Peptidoglycan is composed of polysaccharide chains cross-linked by short peptides. The polysaccharide chains contain alternate units of NAM and NAG.
  • 3.6K
  • 24 Jan 2022
Topic Review
Short-Term Memory
Short-term memory (or "primary" or "active memory") is the capacity for holding, but not manipulating, a small amount of information in mind in an active, readily available state for a short period of time. For example, short-term memory can be used to remember a phone number that has just been recited. The duration of short-term memory (when rehearsal or active maintenance is prevented) is believed to be in the order of seconds. A commonly cited capacity of items to remember is The Magical Number Seven, Plus or Minus Two (also called Miller's Law, despite Miller calling the figure "little more than a joke" (Miller, 1989, page 401)). Cowan (2001) suggests that a more realistic figure is 4±1 items. In contrast, long-term memory holds information indefinitely. Short-term memory should be distinguished from working memory, which refers to structures and processes used for temporarily storing and manipulating information (see details below).
  • 3.5K
  • 12 Oct 2022
Biography
Abraham Pais
Abraham Pais (/peɪs/; May 19, 1918 – July 28, 2000) was a Dutch-United States physicist and science historian. Pais earned his Ph.D. from University of Utrecht just prior to a Nazi ban on Jewish participation in Dutch universities during World War II. When the Nazis began the forced relocation of Dutch Jews, he went into hiding, but was later arrested and saved only by the end of the war.[1]
  • 3.5K
  • 29 Nov 2022
Topic Review
Neuroprotective Effects of Quercetin
Quercetin is a flavonoid compound present in a wide variety of vegetables and fruit, such as onion, asparagus, red leaf lettuce, cilantro, lovage, dill, capers, apples, and berries. Quercetin represents the highest percentage of total flavonoid intake and is the most important component of flavonol subclass, often the base of other flavonoids. Thus, quercetin has been demonstrated to exert neuroprotective effects in several neurodegenerative disorders as well as antioxidant, anti-inflammatory, anti-cancer, anti-obesity, anti-viral and anti-microbial properties, and cardioprotective and hepatoprotective activities.
  • 3.5K
  • 07 Mar 2021
Topic Review
Malacostraca
Malacostraca (from New Latin; from grc μαλακός (malakós) 'soft', and όστρακον "shell") is the largest of the six classes of crustaceans, containing about 40,000 living species, divided among 16 orders. Its members, the malacostracans, display a great diversity of body forms and include crabs, lobsters, crayfish, shrimp, krill, prawns, woodlice, amphipods, mantis shrimp and many other, less familiar animals. They are abundant in all marine environments and have colonised freshwater and terrestrial habitats. They are segmented animals, united by a common body plan comprising 20 body segments (rarely 21), and divided into a head, thorax, and abdomen.
  • 3.5K
  • 31 Oct 2022
Topic Review
Ornithorhynchus
The platypus (Ornithorhynchus anatinus), sometimes referred to as the duck-billed platypus, is a semiaquatic, egg-laying mammal endemic to eastern Australia, including Tasmania. The platypus is the sole living representative or monotypic taxon of its family (Ornithorhynchidae) and genus (Ornithorhynchus), though a number of related species appear in the fossil record. Together with the four species of echidna, it is one of the five extant species of monotremes, mammals that lay eggs instead of giving birth to live young. Like other monotremes, it senses prey through electrolocation. It is one of the few species of venomous mammals, as the male platypus has a spur on the hind foot that delivers a venom, capable of causing severe pain to humans. The unusual appearance of this egg-laying, duck-billed, beaver-tailed, otter-footed mammal baffled European naturalists when they first encountered it, and the first scientists to examine a preserved platypus body (in 1799) judged it a fake, made of several animals sewn together. The unique features of the platypus make it an important subject in the study of evolutionary biology, and a recognisable and iconic symbol of Australia . It is culturally significant to several Aboriginal peoples of Australia, who also used to hunt the animal for food. It has appeared as a mascot at national events and features on the reverse of the Australian twenty-cent coin, and the platypus is the animal emblem of the state of New South Wales. Until the early 20th century, humans hunted the platypus for its fur, but it is now protected throughout its range. Although captive-breeding programs have had only limited success, and the platypus is vulnerable to the effects of pollution, it is not under any immediate threat. (As of 2020), the platypus is a legally protected species in all states where it occurs. It is listed as an endangered species in South Australia and Victoria and has been recommended for listing in New South Wales. The species is classified as a near-threatened species by the IUCN, but a November 2020 report has recommended that it is upgraded to threatened species under the federal EPBC Act, due to habitat destruction and declining numbers in all states.
  • 3.5K
  • 10 Nov 2022
Biography
Max Tegmark
Max Erik Tegmark[1] (born 5 May 1967) is a Swedish-American physicist, cosmologist and machine learning researcher. He is a professor at the Massachusetts Institute of Technology and the scientific director of the Foundational Questions Institute. He is also a co-founder of the Future of Life Institute and a supporter of the effective altruism movement, and has received research grants from Elon
  • 3.5K
  • 22 Nov 2022
Topic Review
Human Embryogenesis
Human embryogenesis refers to the development and formation of the human embryo. It is characterised by the process of cell division and cellular differentiation of the embryo that occurs during the early stages of development. In biological terms, human development entails growth from a one-celled zygote to an adult human being. Fertilisation occurs when the sperm cell successfully enters and fuses with an egg cell (ovum). The genetic material of the sperm and egg then combine to form a single cell called a zygote and the germinal stage of prenatal development commences. Embryogenesis covers the first eight weeks of development; at the beginning of the ninth week the embryo is termed a fetus. Human embryology is the study of this development during the first eight weeks after fertilisation. The normal period of gestation (pregnancy) is nine months or 38 weeks. The germinal stage refers to the time from fertilization through the development of the early embryo until implantation is completed in the uterus. The germinal stage takes around 10 days. During this stage, the zygote begins to divide, in a process called cleavage. A blastocyst is then formed and implanted in the uterus. Embryogenesis continues with the next stage of gastrulation, when the three germ layers of the embryo form in a process called histogenesis, and the processes of neurulation and organogenesis follow. In comparison to the embryo, the fetus has more recognizable external features and a more complete set of developing organs. The entire process of embryogenesis involves coordinated spatial and temporal changes in gene expression, cell growth and cellular differentiation. A nearly identical process occurs in other species, especially among chordates.
  • 3.4K
  • 28 Apr 2023
Biography
Alan Sokal
Alan David Sokal (/ˈsoʊkəl/; born January 24, 1955) is a professor of mathematics at University College London and professor of physics at New York University. He works in statistical mechanics and combinatorics. He is a critic of postmodernism, and caused the Sokal affair in 1996 when his deliberately nonsensical paper was published by Duke University's Social Text. He also works to counter
  • 3.4K
  • 30 Dec 2022
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