Manufacturing is the production of products for use or sale using labour and machines, tools and biological processing, or formulation. The term may refer to a range of human activity, from handicraft to high tech, but is most applied to industrial design, in which raw materials are transformed into finished goods on a large scale; such finished goods may be sold to other manufacturers for the production of other, more complex products, such as aircraft, household appliances, sports equipment or automobiles, or sold to wholesalers, who in turn sell them to retailers, who sell them to end users and consumers. Manufacturing engineering or manufacturing process are the steps through which raw materials are transformed into a final product; the manufacturing process begins with the product design, materials specification from which the product is made. These materials are modified through manufacturing processes to become the required part. Modern manufacturing includes all intermediate processes required in the production and integration of a product's components.
Some industries, such as semiconductor and steel manufacturers use the term fabrication instead. The manufacturing sector is connected with engineering and industrial design. Examples of major manufacturers in North America include General Motors Corporation, General Electric, Procter & Gamble, General Dynamics, Boeing and Precision Castparts. Examples in Europe include Volkswagen Siemens, FCA and Michelin. Examples in Asia include Toyota, Panasonic, LG, Samsung and Tata Motors. In its earliest form, manufacturing was carried out by a single skilled artisan with assistants. Training was by apprenticeship. In much of the pre-industrial world, the guild system protected the privileges and trade secrets of urban artisans. Before the Industrial Revolution, most manufacturing occurred in rural areas, where household-based manufacturing served as a supplemental subsistence strategy to agriculture. Entrepreneurs organized a number of manufacturing households into a single enterprise through the putting-out system.
Toll manufacturing is an arrangement whereby a first firm with specialized equipment processes raw materials or semi-finished goods for a second firm. Manufacturing Engineering Agile manufacturing American system of manufacturing British factory system of manufacturing Craft or guild system Fabrication Flexible manufacturing Just-in-time manufacturing Lean manufacturing Mass customization – 3D printing, design-your-own web sites for sneakers, fast fashion Mass production Ownership Packaging and labeling Prefabrication Putting-out system Rapid manufacturing Reconfigurable manufacturing system Soviet collectivism in manufacturing History of numerical control Emerging technologies have provided some new growth in advanced manufacturing employment opportunities in the Manufacturing Belt in the United States. Manufacturing provides important material support for national infrastructure and for national defense. On the other hand, most manufacturing may involve significant environmental costs; the clean-up costs of hazardous waste, for example, may outweigh the benefits of a product that creates it.
Hazardous materials may expose workers to health risks. These costs are now well known and there is effort to address them by improving efficiency, reducing waste, using industrial symbiosis, eliminating harmful chemicals; the negative costs of manufacturing can be addressed legally. Developed countries regulate manufacturing activity with environmental laws. Across the globe, manufacturers can be subject to regulations and pollution taxes to offset the environmental costs of manufacturing activities. Labor unions and craft guilds have played a historic role in the negotiation of worker rights and wages. Environment laws and labor protections that are available in developed nations may not be available in the third world. Tort law and product liability impose additional costs on manufacturing; these are significant dynamics in the ongoing process, occurring over the last few decades, of manufacture-based industries relocating operations to "developing-world" economies where the costs of production are lower than in "developed-world" economies.
Manufacturing has unique health and safety challenges and has been recognized by the National Institute for Occupational Safety and Health as a priority industry sector in the National Occupational Research Agenda to identify and provide intervention strategies regarding occupational health and safety issues. Surveys and analyses of trends and issues in manufacturing and investment around the world focus on such things as: The nature and sources of the considerable variations that occur cross-nationally in levels of manufacturing and wider industrial-economic growth. In addition to general overviews, researchers have examined the features and factors affecting particular key aspects of manufacturing development, they have compared production and investment in a range of Western and non-Western countries and presented case studies of growth and performance in important individual industries and market-economic sectors. On June 26, 2009, Jeff Immelt, the CEO of General Electric, called for the United States to increase its manufacturing base employment to 20% of the workforce, commenting that the U.
S. has outsourced too much in some areas and can no longer rely on the financial sector and consumer spending to drive demand. Further, while U. S. manufacturing performs well compared to the rest of the U. S. economy, research shows that it performs poorly compared to manufacturing in other high-wage countries. A total of 3.2 million – one in six U. S. manuf
United States Department of Defense
The Department of Defense is an executive branch department of the federal government charged with coordinating and supervising all agencies and functions of the government concerned directly with national security and the United States Armed Forces. The department is the largest employer in the world, with nearly 1.3 million active duty servicemen and women as of 2016. Adding to its employees are over 826,000 National Guardsmen and Reservists from the four services, over 732,000 civilians bringing the total to over 2.8 million employees. Headquartered at the Pentagon in Arlington, just outside Washington, D. C. the DoD's stated mission is to provide "the military forces needed to deter war and ensure our nation's security". The Department of Defense is headed by the Secretary of Defense, a cabinet-level head who reports directly to the President of the United States. Beneath the Department of Defense are three subordinate military departments: the United States Department of the Army, the United States Department of the Navy, the United States Department of the Air Force.
In addition, four national intelligence services are subordinate to the Department of Defense: the Defense Intelligence Agency, the National Security Agency, the National Geospatial-Intelligence Agency, the National Reconnaissance Office. Other Defense Agencies include the Defense Advanced Research Projects Agency, the Defense Logistics Agency, the Missile Defense Agency, the Defense Health Agency, Defense Threat Reduction Agency, the Defense Security Service, the Pentagon Force Protection Agency, all of which are under the command of the Secretary of Defense. Additionally, the Defense Contract Management Agency provides acquisition insight that matters, by delivering actionable acquisition intelligence from factory floor to the warfighter. Military operations are managed by ten functional Unified combatant commands; the Department of Defense operates several joint services schools, including the Eisenhower School and the National War College. The history of the defense of the United States started with the Continental Congress in 1775.
The creation of the United States Army was enacted on 14 June 1775. This coincides with the American holiday Flag Day; the Second Continental Congress would charter the United States Navy, on 13 October 1775, create the United States Marine Corps on 10 November 1775. The Preamble of the United States Constitution gave the authority to the federal government to defend its citizens: We the People of the United States, in Order to form a more perfect Union, establish Justice, insure domestic Tranquility, provide for the common defence, promote the general Welfare, secure the Blessings of Liberty to ourselves and our Posterity, do ordain and establish this Constitution for the United States of America. Upon the seating of the first Congress on 4 March 1789, legislation to create a military defense force stagnated as they focused on other concerns relevant to setting up the new government. President George Washington went to Congress to remind them of their duty to establish a military twice during this time.
On the last day of the session, 29 September 1789, Congress created the War Department, historic forerunner of the Department of Defense. The War Department handled naval affairs until Congress created the Navy Department in 1798; the secretaries of each of these departments reported directly to the president as cabinet-level advisors until 1949, when all military departments became subordinate to the Secretary of Defense. After the end of World War II, President Harry Truman proposed creation of a unified department of national defense. In a special message to Congress on 19 December 1945, the President cited both wasteful military spending and inter-departmental conflicts. Deliberations in Congress went on for months focusing on the role of the military in society and the threat of granting too much military power to the executive. On 26 July 1947, Truman signed the National Security Act of 1947, which set up a unified military command known as the "National Military Establishment", as well as creating the Central Intelligence Agency, the National Security Council, National Security Resources Board, United States Air Force and the Joint Chiefs of Staff.
The act placed the National Military Establishment under the control of a single Secretary of Defense. The National Military Establishment formally began operations on 18 September, the day after the Senate confirmed James V. Forrestal as the first Secretary of Defense; the National Military Establishment was renamed the "Department of Defense" on 10 August 1949 and absorbed the three cabinet-level military departments, in an amendment to the original 1947 law. Under the Department of Defense Reorganization Act of 1958, channels of authority within the department were streamlined, while still maintaining the ordinary authority of the Military Departments to organize and equip their associated forces; the Act clarified the overall decision-making authority of the Secretary of Defense with respect to these subordinate Military Departments and more defined the operational chain of command over U. S. military forces as running from the president to the Secretary of Defense and to the unified combatant commanders.
Provided in this legislation was a centralized research authority, the Advanced Research Projects Agency known as DARPA. The act was written and promoted by the Eisenhower administration, was signed into law 6 August 1958; the Secretary of Defense, appointed by the president with the advice and consent of the Senate, is by federal law (1
United States Congress
The United States Congress is the bicameral legislature of the Federal Government of the United States. The legislature consists of two chambers: the House of the Senate; the Congress meets in the United States Capitol in Washington, D. C.. Both senators and representatives are chosen through direct election, though vacancies in the Senate may be filled by a gubernatorial appointment. Congress has 535 voting members: 100 senators; the House of Representatives has six non-voting members representing Puerto Rico, American Samoa, the Northern Mariana Islands, the U. S. Virgin Islands, the District of Columbia in addition to its 435 voting members. Although they cannot vote in the full house, these members can address the house and vote in congressional committees, introduce legislation; the members of the House of Representatives serve two-year terms representing the people of a single constituency, known as a "district". Congressional districts are apportioned to states by population using the United States Census results, provided that each state has at least one congressional representative.
Each state, regardless of population or size, has two senators. There are 100 senators representing the 50 states; each senator is elected at-large in their state for a six-year term, with terms staggered, so every two years one-third of the Senate is up for election. To be eligible for election, a candidate must be aged at least 25 or 30, have been a citizen of the United States for seven or nine years, be an inhabitant of the state which they represent; the Congress was created by the Constitution of the United States and first met in 1789, replacing in its legislative function the Congress of the Confederation. Although not mandated, in practice since the 19th century, Congress members are affiliated with the Republican Party or with the Democratic Party and only with a third party or independents. Article One of the United States Constitution states, "All legislative Powers herein granted shall be vested in a Congress of the United States, which shall consist of a Senate and House of Representatives."
The House and Senate are equal partners in the legislative process—legislation cannot be enacted without the consent of both chambers. However, the Constitution grants each chamber some unique powers; the Senate ratifies treaties and approves presidential appointments while the House initiates revenue-raising bills. The House initiates impeachment cases. A two-thirds vote of the Senate is required before an impeached person can be forcibly removed from office; the term Congress can refer to a particular meeting of the legislature. A Congress covers two years; the Congress ends on the third day of January of every odd-numbered year. Members of the Senate are referred to as senators. Scholar and representative Lee H. Hamilton asserted that the "historic mission of Congress has been to maintain freedom" and insisted it was a "driving force in American government" and a "remarkably resilient institution". Congress is the "heart and soul of our democracy", according to this view though legislators achieve the prestige or name recognition of presidents or Supreme Court justices.
One analyst argues that it is not a reactive institution but has played an active role in shaping government policy and is extraordinarily sensitive to public pressure. Several academics described Congress: Congress reflects us in all our strengths and all our weaknesses, it reflects our regional idiosyncrasies, our ethnic and racial diversity, our multitude of professions, our shadings of opinion on everything from the value of war to the war over values. Congress is the government's most representative body... Congress is charged with reconciling our many points of view on the great public policy issues of the day. Congress is changing and is in flux. In recent times, the American south and west have gained House seats according to demographic changes recorded by the census and includes more minorities and women although both groups are still underrepresented. While power balances among the different parts of government continue to change, the internal structure of Congress is important to understand along with its interactions with so-called intermediary institutions such as political parties, civic associations, interest groups, the mass media.
The Congress of the United States serves two distinct purposes that overlap: local representation to the federal government of a congressional district by representatives and a state's at-large representation to the federal government by senators. Most incumbents seek re-election, their historical likelihood of winning subsequent elections exceeds 90 percent; the historical records of the House of Representatives and the Senate are maintained by the Center for Legislative Archives, a part of the National Archives and Records Administration. Congress is directly responsible for the governing of the District of Columbia, the current seat of the federal government; the First Continental Congress was a gathering of representatives from twelve of the thirteen British Colonies in North America. On July 4, 1776, the Second Continental Congress adopted the Declaration of Independence, referring to the new nation as the "United States of America"; the Articles of Confederation in 1781 created the Congress of the Confederation, a
Government procurement in the United States
Government procurement in the United States is the process by which the federal and local government bodies in the United States acquire goods and interests in real property. In FY 2016 alone, the US Federal Government spent $461B on contracts. Contracts for federal government procurement involve appropriated funds spent on supplies and interests in real property by and for the use of the Federal Government through purchase or lease, whether the supplies, services, or interests are in existence or must be created, developed and evaluated. See 48 C. F. R. § 2.101. Federal Government contracting has the same legal elements as contracting between private parties: a lawful purpose, competent contracting parties, an offer, an acceptance that complies with the terms of the offer, mutuality of obligation, consideration. However, federal procurement is much more regulated, subject to volumes of statutes dealing with Federal contracts and the Federal contracting process in Titles 10, 31, 40, 41 of the United States Code.
Private parties entering into a contract with one another have more freedom to establish a broad range of contract terms by mutual consent than a private party entering into a contract with the Federal Government. Each private party can obligate itself in any lawful manner. Federal Government contracts allow for the creation of contract terms by mutual consent of the parties, but many areas addressed by mutual consent in commercial contracts are controlled by law in Federal contracts and require use of prescribed provisions and clauses. In commercial contracting, where one or both parties may be represented by agents whose authority is controlled by the law of agency, the agent is allowed to form a contract only with reference to accepted notions of commercial reasonableness and a few unique statutes that apply. In Federal Government contracting, specific regulatory authority is required for the Government's agent to enter into the contract, that agent's bargaining authority is controlled by statutes and regulations reflecting national policy choices and prudential limitations on the right of Federal employees to obligate Federal funds.
By contrast, in commercial contracting, the law allows each side to rely on the other's authority to make a binding contract on mutually agreeable terms. The authority of a Contracting Officer, the Government's agent, to contract on behalf of the Government is set forth in public documents that a person dealing with the Contracting Officer can review; the Contracting Officer does not have authority to act outside of this warrant or to deviate from the laws and regulations controlling Federal Government contracts. The private contracting party is held to know the limitations of the Contracting Officer's authority if the Contracting Officer does not; this makes contracting with the United States a more structured and restricted process than a commercial one. Federal Procurement Reports provide contract data that may be used for geographical and socio-economic analysis, as well as for measuring and assessing the impact of acquisition policy and management improvements. In Fiscal Year 2010, the top five departments by dollars obligated were: Department of Defense Department of Energy Health and Human Services General Services Administration NASA.
The Top 100 Contractors Report for Fiscal Year 2009 lists contracts totalling $294.6 billion, the top five comprising aerospace and defense contractors: Lockheed Martin Boeing Northrop Grumman General Dynamics Raytheon In the same period, small business contracts totalled $96.8 billion. The Federal Government's authority to enter into contracts derives from the U. S. Constitution, which defines its powers; the Federal Government acts through legislation, implementing regulations, the exercise of those authorities. The Federal Government's power to contract is not set forth expressly and in the U. S. Constitution. However, the U. S. Constitution appears to assume the continued vitality "Engagements" entered into under the Articles of Confederation. U. S. Const. Art. VI. Moreover, the power to contract was and is regarded at law as incidental to the Federal Government's execution of its other powers. An early Supreme Court case, United States v. Thomas Tingey, 30 U. S. 5 Pet. 115, recognized that the United States Government has a right to enter into a contract.
It is an incident to the general right of sovereignty, the United States, within the sphere of the constitutional powers confided to it and through the instrumentality of the proper department to which those powers are confided, enter into contracts not prohibited by law and appropriate to the just exercise of those powers. Scores of statutes now expressly authorize departments and agencies to enter into contracts; the U. S. Congress passes legislation that defines the process and additional legislation that provides the funds. Executive branch agencies enter into the contracts and expend the funds to achieve their Congressionally defined missions; when disputes arise, administrative processes within the agencies may resolve them, or the contractor can appeal to the courts. The procurement process for executive branch agencies is governed by the Armed Services Procurement Act and the Federal Property and Administrative Services Act. To address the many rules imposed by Congress and the courts, a body of administrative law has been developed thr
A soldier is one who fights as part of an army. A soldier can be a conscripted or volunteer enlisted person, a non-commissioned officer, or an officer; the word soldier derives from the Middle English word soudeour, from Old French soudeer or soudeour, meaning mercenary, from soudee, meaning shilling's worth or wage, from sou or soud, shilling. The word is related to the Medieval Latin soldarius, meaning soldier; these words derive from the Late Latin word solidus, referring to an Ancient Roman coin used in the Byzantine Empire. In most armies use of the word "soldier" has taken on a more general meaning due to the increasing specialization of military occupations that require different areas of knowledge and skill-sets; as a result, "soldiers" are referred to by names or ranks which reflect an individual's military occupation specialty arm, service, or branch of military employment, their type of unit, or operational employment or technical use such as: trooper, commando, infantryman, paratrooper, ranger, engineer, craftsman, medic, or a gunner.
In many countries soldiers serving in specific occupations are referred to by terms other than their occupational name. For example, military police personnel in the British Army are known as "red caps" because of the colour of their caps. Infantry are sometimes called "grunts" or "squaddies", while U. S. Army artillery crews, or "gunners," are sometimes referred to as "redlegs", from the service branch color for artillery. U. S. soldiers are called "G. I.s". French Marine Infantry are called marsouins because of their amphibious role. Military units in most armies have nicknames of this type, arising either from items of distinctive uniform, some historical connotation or rivalry between branches or regiments; some soldiers, such as conscripts or draftees, serve a single limited term. Others choose to serve until retirement. In the United States, military members can retire after 20 years. In other countries, the term of service is 30 years, hence the term "30-year man". According to the United Nations, 10-30% of all soldiers worldwide are women.
Airman Marine Sailor Media related to Soldier at Wikimedia Commons
A measuring instrument is a device for measuring a physical quantity. In the physical sciences, quality assurance, engineering, measurement is the activity of obtaining and comparing physical quantities of real-world objects and events. Established standard objects and events are used as units, the process of measurement gives a number relating the item under study and the referenced unit of measurement. Measuring instruments, formal test methods which define the instrument's use, are the means by which these relations of numbers are obtained. All measuring instruments are subject to varying degrees of instrument error and measurement uncertainty. Scientists and other humans use a vast range of instruments to perform their measurements; these instruments may range from simple objects such as rulers and stopwatches to electron microscopes and particle accelerators. Virtual instrumentation is used in the development of modern measuring instruments. In the past, a common time measuring instrument was the sundial.
Today, the usual measuring instruments for time are watches. For accurate measurement of time an atomic clock is used. Stop watches are used to measure time in some sports. Energy is measured by an energy meter. Examples of energy meters include: An electricity meter measures energy directly in kilowatt hours. A gas meter measures energy indirectly by recording the volume of gas used; this figure can be converted to a measure of energy by multiplying it by the calorific value of the gas. A physical system that exchanges energy may be described by the amount of energy exchanged per time-interval called power or flux of energy. For the ranges of power-values see: Orders of magnitude. Action describes, its dimension is the same as that of an angular momentum. A phototube provides a voltage measurement which permits the calculation of the quantized action of light. See photoelectric effect; this includes basic quantities found in classical- and continuum mechanics. Length, distance, or range meterFor the ranges of length-values see: Orders of magnitude PlanimeterFor the ranges of area-values see: Orders of magnitude Buoyant weight Overflow trough Measuring cup Flow measurement devices Graduated cylinder Pipette Eudiometer, pneumatic trough If the mass density of a solid is known, weighing allows to calculate the volume.
For the ranges of volume-values see: Orders of magnitude Gas meter Mass flow meter Metering pump Water meter Airspeed indicator Radar gun, a Doppler radar device, using the Doppler effect for indirect measurement of velocity. LIDAR speed gun Speedometer Tachometer Tachymeter VariometerFor the ranges of speed-values see: Orders of magnitude Accelerometer Balance Automatic checkweighing machines Katharometer Weighing scales Inertial balance Mass spectrometers measure the mass-to-charge ratio, not the mass. For the ranges of mass-values see: Orders of magnitude Ballistic pendulum Force gauge Spring scale Strain gauge Torsion balance Tribometer Anemometer Barometer used to measure the atmospheric pressure. Manometer see pressure measurement and pressure sensor Pitot tube Tire-pressure gauge in industry and mobilityFor the ranges of pressure-values see: Orders of magnitude Circumferentor Cross staff Goniometer Graphometer Protractor Quadrant Reflecting instruments Octant Reflecting circles Sextant Theodolite Stroboscope TachometerFor the value-ranges of angular velocity see: Orders of magnitude For the ranges of frequency see: Orders of magnitude Dynamometer de Prony brake Torque wrench See the section about navigation below.
Dumpy level Laser line level Spirit level Gyroscope Ballistic pendulum, indirectly by calculation and or gauging Considerations related to electric charge dominate electricity and electronics. Electrical charges interact via a field; that field is called electric field. If the charge doesn't move. If the charge moves, thus realizing an electric current in an electrically neutral conductor, that field is called magnetic. Electricity can be given a quality — a potential, and electricity has the electric charge. Energy in elementary electrodynamics is calculated by multiplying the potential by the amount of charge found at that potential: potential times charge. Electrometer is used to reconfirm the phenomenon of contact electricity leading to triboelectric sequences. Torsion balance force, see above. For the ranges of charge values see: Orders of magnitude Ammeter Clamp meter Galvanometer D'Arsonval galvanometer Oscilloscope allows quantifying time-dependent voltages Voltmeter Ohmmeter Time-domain reflectometer characterizes and locates faults in metallic cables by runtime measurements of electric signals.
Wheatstone bridge Capacitance meter Inductance meter Electric energy meter Electricity meter Wattmeter Field mill See the relevant section in the article about the magnetic field. Compass Hall effect sensor Magnetometer Proton magnetometer SQUIDFor the ranges of magnetic field see: Orders of magnitude Multimeter, combines the functions of ammeter and ohmmeter as a minimum. LCR meter, combines the functions of ohmmeter, capacitance meter and inductance meter
Clothing is a collective term for items worn on the body. Clothing can be made of animal skin, or other thin sheets of materials put together; the wearing of clothing is restricted to human beings and is a feature of all human societies. The amount and type of clothing worn depend on body type and geographic considerations; some clothing can be gender-specific. Physically, clothing serves many purposes: it can serve as protection from the elements and can enhance safety during hazardous activities such as hiking and cooking, it protects the wearer from rough surfaces, rash-causing plants, insect bites, splinters and prickles by providing a barrier between the skin and the environment. Clothes can insulate against cold or hot conditions, they can provide a hygienic barrier, keeping infectious and toxic materials away from the body. Clothing provides protection from ultraviolet radiation. Wearing clothes is a social norm, being deprived of clothing in front of others may be embarrassing, or not wearing clothes in public such that genitals, breasts or buttocks are visible could be seen as indecent exposure.
There is no easy way to determine when clothing was first developed, but some information has been inferred by studying lice which estimates the introduction of clothing at 42,000–72,000 years ago. The most obvious function of clothing is to improve the comfort of the wearer, by protecting the wearer from the elements. In hot climates, clothing provides protection from sunburn or wind damage, while in cold climates its thermal insulation properties are more important. Shelter reduces the functional need for clothing. For example, hats and other outer layers are removed when entering a warm home if one is living or sleeping there. Clothing has seasonal and regional aspects, so that thinner materials and fewer layers of clothing are worn in warmer regions and seasons than in colder ones. Clothing performs a range of social and cultural functions, such as individual and gender differentiation, social status. In many societies, norms about clothing reflect standards of modesty, religion and social status.
Clothing may function as a form of adornment and an expression of personal taste or style. Clothing can be and has in the past been made from a wide variety of materials. Materials have ranged from leather and furs to woven materials, to elaborate and exotic natural and synthetic fabrics. Not all body coverings are regarded as clothing. Articles carried rather than worn, worn on a single part of the body and removed, worn purely for adornment, or those that serve a function other than protection, are considered accessories rather than clothing, except for shoes. Clothing protects against many things. Clothes protect people from the elements, including rain, snow and other weather, as well as from the sun. However, clothing, too sheer, small, etc. offers less protection. Appropriate clothes can reduce risk during activities such as work or sport; some clothing protects from specific hazards, such as insects, noxious chemicals, weather and contact with abrasive substances. Conversely, clothing may protect the environment from the clothing wearer: for instance doctors wear medical scrubs.
Humans have been ingenious in devising clothing solutions to environmental or other hazards: such as space suits, air conditioned clothing, diving suits, bee-keeper gear, motorcycle leathers, high-visibility clothing, other pieces of protective clothing. Meanwhile, the distinction between clothing and protective equipment is not always clear-cut, since clothes designed to be fashionable have protective value and clothes designed for function consider fashion in their design; the choice of clothes has social implications. They cover parts of the body that social norms require to be covered, act as a form of adornment, serve other social purposes. Someone who lacks the means to procure reasonable clothing due to poverty or affordability, or lack of inclination, is sometimes said to be scruffy, ragged, or shabby. Serious books on clothing and its functions appear from the 19th century as imperialists dealt with new environments such as India and the tropics; some scientific research into the multiple functions of clothing in the first half of the 20th century, with publications such as J.
C. Flügel's Psychology of Clothes in 1930, Newburgh's seminal Physiology of Heat Regulation and The Science of Clothing in 1949. By 1968, the field of environmental physiology had advanced and expanded but the science of clothing in relation to environmental physiology had changed little. There has since been considerable research, the knowledge base has grown but the main concepts remain unchanged, indeed Newburgh's book is still cited by contemporary authors, including those attempting to develop thermoregulatory models of clothing development. In most cultures, gender differentiation of clothing is considered appropriate; the differences are in styles and fabrics. In Western societies, skirts and high-heeled shoes are seen as women's clothing, while neckties are seen as men's clothing. Trousers were once seen as male clothing, but can nowadays be worn by both genders. Male clothes are more practical, but a wider range of clothing styles are available for females. Males are allowed to bare their chests in a greater variety of public places.