A blast furnace is a type of metallurgical furnace used for smelting to produce industrial metals, generally pig iron, but also others such as lead or copper. Blast refers to the combustion air being "forced" or supplied above atmospheric pressure.In a blast furnace, fuel (coke), ores, and flux (limestone) are continuously supplied through the top of the furnace, while a hot blast of air (sometimes with oxygen enrichment) is blown into the lower section of the furnace through a series of pipes called tuyeres, so that the chemical reactions take place throughout the furnace as the material falls downward. The end products are usually molten metal and slag phases tapped from the bottom, and waste gases (flue gas) exiting from the top of the furnace. The downward flow of the ore along with the flux in contact with an upflow of hot, carbon monoxide-rich combustion gases is a countercurrent exchange and chemical reaction process.In contrast, air furnaces (such as reverberatory furnaces) are naturally aspirated, usually by the convection of hot gases in a chimney flue. According to this broad definition, bloomeries for iron, blowing...

The Canada goose (Branta canadensis), (sometimes called Canadian goose), is a large wild goose with a black head and neck, white cheeks, white under its chin, and a brown body. It is native to the arctic and temperate regions of North America, and it is occasionally found during migration across the Atlantic in northern Europe. It has been introduced to the United Kingdom, Ireland, Finland, Sweden, Denmark, New Zealand, Japan, Chile, Argentina, and the Falkland Islands. Like most geese, the Canada goose is primarily herbivorous and normally migratory; often found on or close to fresh water, the Canada goose is also common in brackish marshes, estuaries, and lagoons. Extremely adept at living in human-altered areas, Canada geese have established breeding colonies in urban and cultivated habitats, which provide food and few natural predators. The success of this common park species has led to its often being considered a pest species because of its excrement, its depredation of crops, its noise, its aggressive territorial behavior toward both humans and other animals, and its habit of...

Obesity is a medical condition, sometimes considered a disease, in which excess body fat has accumulated to such an extent that it may negatively affect health. People are classified as obese when their body mass index (BMI)—a person's weight divided by the square of the person's height—is over 30 kg/m2; the range 25–30 kg/m2 is defined as overweight. Some East Asian countries use lower values to calculate obesity. Obesity is a major cause of disability and is correlated with various diseases and conditions, particularly cardiovascular diseases, type 2 diabetes, obstructive sleep apnea, certain types of cancer, and osteoarthritis.Obesity has individual, socioeconomic, and environmental causes. Some known causes are diet, physical activity, automation, urbanization, genetic susceptibility, medications, mental disorders, economic policies, endocrine disorders, and exposure to endocrine-disrupting chemicals.While a majority of obese individuals at any given time are attempting to lose...

Critical thinking is the analysis of available facts, evidence, observations, and arguments to form a judgment. The subject is complex; several different definitions exist, which generally include the rational, skeptical, and unbiased analysis or evaluation of factual evidence. Critical thinking is self-directed, self-disciplined, self-monitored, and self-corrective thinking. It presupposes assent to rigorous standards of excellence and mindful command of their use. It entails effective communication and problem-solving abilities as well as a commitment to overcome native egocentrism and sociocentrism. History The earliest records of critical thinking are the teachings of Socrates, according to Plato. These included a part in Plato's early dialogues, where Socrates engages with one or more interlocutors on the issue of ethics such as question whether it was right for Socrates to escape from prison. The philosopher considered and reflected on this question and came to the conclusion that escape violates all the things that he holds higher than himself: the laws of Athens and the guiding voice that Socrates...

The clambake or clam bake, also known as the New England clambake, is a traditional method of cooking seafood, such as lobster, mussels, crabs, scallops, soft-shell clams, and quahogs. The food is traditionally cooked by steaming the ingredients over layers of seaweed in a pit oven. The shellfish can be supplemented with vegetables, such as onions, carrots, and corn on the cob. Clambakes are usually held on festive occasions along the coast of New England, and at fundraisers and political events. Some restaurants and caterers offer clambake-style food. History It is known that Native Americans in what is now the eastern United States developed techniques to bake (or steam) clams, at least in Florida. Contrary to legend, though, American colonists did not learn to enjoy baked clams from Native Americans. The colonists did not consider clams to be an acceptable human food and instead fed clams to pigs, except during times of famine.Author Andew W. German concluded, "There is no question that Native American peoples have been consuming clams for four thousand years but there is little evidence that they prepared...

Huygens ( HOY-gənz) was an atmospheric entry robotic space probe that landed successfully on Saturn's moon Titan in 2005. Built and operated by the European Space Agency (ESA), launched by NASA, it was part of the Cassini–Huygens mission and became the first spacecraft to land on Titan and the farthest landing from Earth a spacecraft has ever made. The probe was named after the 17th-century Dutch astronomer Christiaan Huygens, who discovered Titan in 1655. The combined Cassini–Huygens spacecraft was launched from Earth on October 15, 1997. Huygens separated from the Cassini orbiter on December 25, 2004, and landed on Titan on January 14, 2005 near the Adiri region. Huygens's landing is so far the only one accomplished in the outer Solar System, and was also the first on a moon other than Earth's.Huygens touched down on land, although the possibility that it would touch down in an ocean was also taken into account in its design. The probe was designed to gather data for a few hours in the atmosphere, and possibly...

Glucagon is a peptide hormone, produced by alpha cells of the pancreas. It raises concentration of glucose and fatty acids in the bloodstream, and is considered to be the main catabolic hormone of the body. It is also used as a medication to treat a number of health conditions. Its effect is opposite to that of insulin, which lowers extracellular glucose. It is produced from proglucagon, encoded by the GCG gene. The pancreas releases glucagon when the amount of glucose in the bloodstream is too low. Glucagon causes the liver to engage in glycogenolysis: converting stored glycogen into glucose, which is released into the bloodstream. High blood-glucose levels, on the other hand, stimulate the release of insulin. Insulin allows glucose to be taken up and used by insulin-dependent tissues. Thus, glucagon and insulin are part of a feedback system that keeps blood glucose levels stable. Glucagon increases energy expenditure and is elevated under conditions of stress. Glucagon belongs to the secretin family of hormones. Structure Glucagon is a 29-amino acid polypeptide. Its primary structure in humans is: NH2...

Number theory (or arithmetic or higher arithmetic in older usage) is a branch of pure mathematics devoted primarily to the study of the integers and integer-valued functions. German mathematician Carl Friedrich Gauss (1777–1855) said, "Mathematics is the queen of the sciences—and number theory is the queen of mathematics." Number theorists study prime numbers as well as the properties of mathematical objects constructed from integers (for example, rational numbers), or defined as generalizations of the integers (for example, algebraic integers). Integers can be considered either in themselves or as solutions to equations (Diophantine geometry). Questions in number theory are often best understood through the study of analytical objects (for example, the Riemann zeta function) that encode properties of the integers, primes or other number-theoretic objects in some fashion (analytic number theory). One may also...

In religion and theology, revelation is the revealing or disclosing of some form of truth or knowledge through communication with a deity or other supernatural entity or entities. Background Inspiration – such as that bestowed by God on the author of a sacred book – involves a special illumination of the mind, in virtue of which the recipient conceives such thoughts as God desires him to commit to writing, and does not necessarily involve supernatural communication.With the Age of Enlightenment in Europe, beginning about the mid-17th century, the development of rationalism, materialism and atheism, the concept of supernatural revelation itself faced skepticism. In The Age of Reason (1794–1809), Thomas Paine developed the theology of deism, rejecting the possibility of miracles and arguing that a revelation can be considered valid only for the original recipient, with all else being hearsay. Types Individual revelation Thomas Aquinas believed in...

PLOS Biology is a monthly peer-reviewed scientific journal covering all aspects of biology. Publication began on October 13, 2003. It is the first journal published by the Public Library of Science. The editor-in-chief is Nonia Pariente.In addition to research articles, the journal publishes magazine content aimed to be accessible to a broad audience. Article types in this section are essays, "unsolved mysteries", editorials, and synopses. Abstracting and indexing The journal is abstracted and indexed in: Biological Abstracts BIOSIS Previews Current Contents/Agriculture, Biology & Environmental Sciences Current Contents/Life Sciences Chemical Abstracts Service Embase Index Medicus/MEDLINE/PubMed Science Citation Index Scopus The Zoological RecordAccording to Journal Citation Reports, the journal had a 2019 impact factor of 7.076. The journal does not list this impact factor on its website. Instead, the journal promotes the use of article level metrics to provide...