title: Executive functions

text: Miyake and Friedman's theory of executive functions proposes that there are three aspects of executive functions: updating, inhibition, and shifting. A cornerstone of this theoretical framework is the understanding that individual differences in executive functions reflect both unity (i.e., common EF skills) and diversity of each component (e.g., shifting-specific). In other words, aspects of updating, inhibition, and shifting are related, yet each remains a distinct entity. First, updating is defined as the continuous monitoring and quick addition or deletion of contents within one's working memory. Second, inhibition is one's capacity to supersede responses that are prepotent in a given situation. Third, shifting is one's cognitive flexibility to switch between different tasks or mental states.


title: Executive functions

text: Miyake and Friedman also suggest that the current body of research in executive functions suggest four general conclusions about these skills. The first conclusion is the unity and diversity aspects of executive functions. Second, recent studies suggest that much of one's EF skills are inherited genetically, as demonstrated in twin studies. Third, clean measures of executive functions can differentiate between normal and clinical or regulatory behaviors, such as ADHD. Last, longitudinal studies demonstrate that EF skills are relatively stable throughout development.


title: Executive functions

text: This model from 2009 integrates theories from other models, and involves a sequential cascade of brain regions involved in maintaining attentional sets in order to arrive at a goal. In sequence, the model assumes the involvement of the posterior dorsolateral prefrontal cortex (DLPFC), the mid-DLPFC, and the posterior and anterior dorsal anterior cingulate cortex (ACC).


title: Executive functions

text: The cognitive task used in the article is selecting a response in the Stroop task, among conflicting color and word responses, specifically a stimulus where the word "green" is printed in red ink. The posterior DLPFC creates an appropriate attentional set, or rules for the brain to accomplish the current goal. For the Stroop task, this involves activating the areas of the brain involved in color perception, and not those involved in word comprehension. It counteracts biases and irrelevant information, like the fact that the semantic perception of the word is more salient to most people than the color in which it is printed.


title: Executive functions

text: Next, the mid-DLPFC selects the representation that will fulfill the goal. The task-relevant information must be separated from other sources of information in the task. In the example, this means focusing on the ink color and not the word.


title: Executive functions

text: The posterior dorsal anterior cingulate cortex (ACC) is next in the cascade, and it is responsible for response selection. This is where the decision is made whether the Stroop task participant will say "green" (the written word and the incorrect answer) or "red" (the font color and correct answer).


title: Executive functions

text: Following the response, the anterior dorsal ACC is involved in response evaluation, deciding whether one's response were correct or incorrect. Activity in this region increases when the probability of an error is higher.


title: Executive functions

text: The activity of any of the areas involved in this model depends on the efficiency of the areas that came before it. If the DLPFC imposes a lot of control on the response, the ACC will require less activity.


title: Executive functions

text: Recent work using individual differences in cognitive style has shown exciting support for this model. Researchers had participants complete an auditory version of the Stroop task, in which either the location or semantic meaning of a directional word had to be attended to. Participants that either had a strong bias toward spatial or semantic information (different cognitive styles) were then recruited to participate in the task. As predicted, participants that had a strong bias toward spatial information had more difficulty paying attention to the semantic information and elicited increased electrophysiological activity from the ACC. A similar activity pattern was also found for participants that had a strong bias toward verbal information when they tried to attend to spatial information.


title: Executive functions

text: Assessment of executive functions involves gathering data from several sources and synthesizing the information to look for trends and patterns across time and settings. Apart from standardized neuropsychological tests, other measures can and should be used, such as behaviour checklists, observations, interviews, and work samples. From these, conclusions may be drawn on the use of executive functions.


title: Executive functions

text: There are several different kinds of instruments (e.g., performance based, self-report) that measure executive functions across development. These assessments can serve a diagnostic purpose for a number of clinical populations.


title: Executive functions

text: The executive system has been traditionally quite hard to define, mainly due to what psychologist Paul W. Burgess calls a lack of "process-behaviour correspondence". That is, there is no single behavior that can in itself be tied to executive function, or indeed executive dysfunction. For example, it is quite obvious what reading-impaired patients cannot do, but it is not so obvious what exactly executive-impaired patients might be incapable of.


title: Executive functions

text: This is largely due to the nature of the executive system itself. It is mainly concerned with the dynamic, "online" co-ordination of cognitive resources, and, hence, its effect can be observed only by measuring other cognitive processes. In similar manner, it does not always fully engage outside of real-world situations. As neurologist Antonio Damasio has reported, a patient with severe day-to-day executive problems may still pass paper-and-pencil or lab-based tests of executive function.


title: Executive functions

text: Theories of the executive system were largely driven by observations of patients with frontal lobe damage. They exhibited disorganized actions and strategies for everyday tasks (a group of behaviors now known as dysexecutive syndrome) although they seemed to perform normally when clinical or lab-based tests were used to assess more fundamental cognitive functions such as memory, learning, language, and reasoning. It was hypothesized that, to explain this unusual behaviour, there must be an overarching system that co-ordinates other cognitive resources.


title: Executive functions

text: Much of the experimental evidence for the neural structures involved in executive functions comes from laboratory tasks such as the Stroop task or the Wisconsin Card Sorting Task (WCST). In the Stroop task, for example, human subjects are asked to name the color that color words are printed in when the ink color and word meaning often conflict (for example, the word "RED" in green ink). Executive functions are needed to perform this task, as the relatively overlearned and automatic behaviour (word reading) has to be inhibited in favour of a less practiced task – naming the ink color. Recent functional neuroimaging studies have shown that two parts of the PFC, the anterior cingulate cortex (ACC) and the dorsolateral prefrontal cortex (DLPFC), are thought to be particularly important for performing this task.


title: Executive functions

text: Other evidence for the involvement of the PFC in executive functions comes from single-cell electrophysiology studies in non-human primates, such as the macaque monkey, which have shown that (in contrast to cells in the posterior brain) many PFC neurons are sensitive to a conjunction of a stimulus and a context. For example, PFC cells might respond to a green cue in a condition where that cue signals that a leftwards fast movement of the eyes and the head should be made, but not to a green cue in another experimental context. This is important, because the optimal deployment of executive functions is invariably context-dependent.


title: Executive functions

text: One example from Miller & Cohen involves a pedestrian crossing the street. In the United States, where cars drive on the right side of the road, an American learns to look left when crossing the street. However, if that American visits a country where cars drive on the left, such as the United Kingdom, then the "opposite" behavior would be required (looking to the right). In this case, the automatic response needs to be suppressed (or augmented) and executive functions must make the American look to the right while in the UK.


title: Executive functions

text: Neurologically, this behavioural repertoire clearly requires a neural system that is able to integrate the stimulus (the road) with a context (US or UK) to cue a behaviour (look left or look right). Current evidence suggests that neurons in the PFC appear to represent precisely this sort of information. Other evidence from single-cell electrophysiology in monkeys implicates ventrolateral PFC (inferior prefrontal convexity) in the control of motor responses. For example, cells that increase their firing rate to NoGo signals as well as a signal that says "don't look there!" have been identified.


title: Executive functions

text: Electrophysiology and functional neuroimaging studies involving human subjects have been used to describe the neural mechanisms underlying attentional biasing. Most studies have looked for activation at the 'sites' of biasing, such as in the visual or auditory cortices. Early studies employed event-related potentials to reveal that electrical brain responses recorded over left and right visual cortex are enhanced when the subject is instructed to attend to the appropriate (contralateral) side of space.


title: Executive functions

text: The advent of bloodflow-based neuroimaging techniques such as functional magnetic resonance imaging (fMRI) and positron emission tomography (PET) has more recently permitted the demonstration that neural activity in a number of sensory regions, including color-, motion-, and face-responsive regions of visual cortex, is enhanced when subjects are directed to attend to that dimension of a stimulus, suggestive of gain control in sensory neocortex. For example, in a typical study, Liu and coworkers presented subjects with arrays of dots moving to the left or right, presented in either red or green. Preceding each stimulus, an instruction cue indicated whether subjects should respond on the basis of the colour or the direction of the dots. Even though colour and motion were present in all stimulus arrays, fMRI activity in colour-sensitive regions (V4) was enhanced when subjects were instructed to attend to the colour, and activity in motion-sensitive regions was increased when subjects were cued to attend to the direction of motion. Several studies have also reported evidence for the biasing signal prior to stimulus onset, with the observation that regions of the frontal cortex tend to come active prior to the onset of an expected stimulus.


title: Executive functions

text: Despite the growing currency of the 'biasing' model of executive functions, direct evidence for functional connectivity between the PFC and sensory regions when executive functions are used, is to date rather sparse. Indeed, the only direct evidence comes from studies in which a portion of frontal cortex is damaged, and a corresponding effect is observed far from the lesion site, in the responses of sensory neurons. However, few studies have explored whether this effect is specific to situations where executive functions are required. Other methods for measuring connectivity between distant brain regions, such as correlation in the fMRI response, have yielded indirect evidence that the frontal cortex and sensory regions communicate during a variety of processes thought to engage executive functions, such as working memory, but more research is required to establish how information flows between the PFC and the rest of the brain when executive functions are used. As an early step in this direction, an fMRI study on the flow of information processing during visuospatial reasoning has provided evidence for causal associations (inferred from the temporal order of activity) between sensory-related activity in occipital and parietal cortices and activity in posterior and anterior PFC. Such approaches can further elucidate the distribution of processing between executive functions in PFC and the rest of the brain.


title: Executive functions

text: A growing body of research demonstrates that bilinguals might show advantages in executive functions, specifically inhibitory control and task switching. A possible explanation for this is that speaking two languages requires controlling one's attention and choosing the correct language to speak. Across development, bilingual infants, children, and elderly show a bilingual advantage when it comes to executive functioning. The advantage does not seem to manifest in younger adults. Bimodal bilinguals, or people who speak one oral language and one sign language, do not demonstrate this bilingual advantage in executive functioning tasks. This may be because one is not required to actively inhibit one language in order to speak the other.


title: Executive functions

text: Bilingual individuals also seem to have an advantage in an area known as conflict processing, which occurs when there are multiple representations of one particular response (for example, a word in one language and its translation in the individual's other language). Specifically, the lateral prefrontal cortex has been shown to be involved with conflict processing. However, there are still some doubts. In a meta-analytic review, researchers concluded that bilingualism did not enhance executive functioning in adults.


title: Executive functions

text: The study of executive function in Parkinson's disease suggests subcortical areas such as the amygdala, hippocampus and basal ganglia are important in these processes. Dopamine modulation of the prefrontal cortex is responsible for the efficacy of dopaminergic drugs on executive function, and gives rise to the Yerkes Dodson Curve. The inverted U represents decreased executive functioning with excessive arousal (or increased catecholamine release during stress), and decreased executive functioning with insufficient arousal. The low activity polymorphism of Catechol-O-methyltransferase is associated with slight increase in performance on executive function tasks in healthy persons. Executive functions are impaired in multiple disorders including anxiety disorder, major depressive disorder, bipolar disorder, attention deficit hyperactivity disorder, schizophrenia and autism. Lesions to the prefrontal cortex, such as in the case of Phineas Gage, may also result in deficits of executive function. Damage to these areas may also manifest in deficits of other areas of function, such as motivation, and social functioning.


title: Executive functions

text: Other important evidence for executive functions processes in the prefrontal cortex have been described. One widely cited review article emphasizes the role of the medial part of the PFC in situations where executive functions are likely to be engaged – for example, where it is important to detect errors, identify situations where stimulus conflict may arise, make decisions under uncertainty, or when a reduced probability of obtaining favourable performance outcomes is detected. This review, like many others, highlights interactions between medial and lateral PFC, whereby posterior medial frontal cortex signals the need for increased executive functions and sends this signal on to areas in dorsolateral prefrontal cortex that actually implement control. Yet there has been no compelling evidence at all that this view is correct, and, indeed, one article showed that patients with lateral PFC damage had reduced ERNs (a putative sign of dorsomedial monitoring/error-feedback) – suggesting, if anything, that the direction of flow of the control could be in the reverse direction. Another prominent theory emphasises that interactions along the perpendicular axis of the frontal cortex, arguing that a 'cascade' of interactions between anterior PFC, dorsolateral PFC, and premotor cortex guides behaviour in accordance with past context, present context, and current sensorimotor associations, respectively.


title: Executive functions

text: Advances in neuroimaging techniques have allowed studies of genetic links to executive functions, with the goal of using the imaging techniques as potential endophenotypes for discovering the genetic causes of executive function.


title: Executive functions

text: More research is required to develop interventions that can improve executive functions and help people generalize those skills to daily activities and settings


title: Inductance

text: Inductance is the tendency of an electrical conductor to oppose a change in the electric current flowing through it. The flow of electric current creates a magnetic field around the conductor. The field strength depends on the magnitude of the current, and follows any changes in current. From Faraday's law of induction, any change in magnetic field through a circuit induces an electromotive force (EMF) (voltage) in the conductors, a process known as electromagnetic induction. This induced voltage created by the changing current has the effect of opposing the change in current. This is stated by Lenz's law, and the voltage is called "back EMF".


title: Inductance

text: Inductance is defined as the ratio of the induced voltage to the rate of change of current causing it. It is a proportionality factor that depends on the geometry of circuit conductors and the magnetic permeability of nearby materials. An electronic component designed to add inductance to a circuit is called an inductor. It typically consists of a coil or helix of wire.


title: Inductance

text: The term "inductance" was coined by Oliver Heaviside in May 1884. It is customary to use the symbol formula_1 for inductance, in honour of the physicist Heinrich Lenz. In the SI system, the unit of inductance is the henry (H), which is the amount of inductance that causes a voltage of one volt, when the current is changing at a rate of one ampere per second. It is named for Joseph Henry, who discovered inductance independently of Faraday.


title: Inductance

text: The history of electromagnetic induction, a facet of electromagnetism, began with observations of the ancients: electric charge or static electricity (rubbing silk on amber), electric current (lightning), and magnetic attraction (lodestone). Understanding the unity of these forces of nature, and the scientific theory of electromagnetism began in the late 18th century.


title: Inductance

text: Electromagnetic induction was first described by Michael Faraday in 1831. In Faraday's experiment, he wrapped two wires around opposite sides of an iron ring. He expected that, when current started to flow in one wire, a sort of wave would travel through the ring and cause some electrical effect on the opposite side. Using a galvanometer, he observed a transient current flow in the second coil of wire each time that a battery was connected or disconnected from the first coil. This current was induced by the change in magnetic flux that occurred when the battery was connected and disconnected. Faraday found several other manifestations of electromagnetic induction. For example, he saw transient currents when he quickly slid a bar magnet in and out of a coil of wires, and he generated a steady (DC) current by rotating a copper disk near the bar magnet with a sliding electrical lead ("Faraday's disk").


title: Inductance

text: A current formula_2 flowing through a conductor generates a magnetic field around the conductor, which is described by Ampere's circuital law. The total magnetic flux formula_3 through a circuit is equal to the product of the perpendicular component of the magnetic flux density and the area of the surface spanning the current path. If the current varies, the magnetic flux formula_3 through the circuit changes. By Faraday's law of induction, any change in flux through a circuit induces an electromotive force (EMF, formula_5) in the circuit, proportional to the rate of change of flux


title: Inductance

text: The negative sign in the equation indicates that the induced voltage is in a direction which opposes the change in current that created it; this is called Lenz's law. The potential is therefore called a back EMF. If the current is increasing, the voltage is positive at the end of the conductor through which the current enters and negative at the end through which it leaves, tending to reduce the current. If the current is decreasing, the voltage is positive at the end through which the current leaves the conductor, tending to maintain the current. Self-inductance, usually just called inductance, formula_1 is the ratio between the induced voltage and the rate of change of the current


title: Inductance

text: Thus, inductance is a property of a conductor or circuit, due to its magnetic field, which tends to oppose changes in current through the circuit. The unit of inductance in the SI system is the henry (H), named after Joseph Henry, which is the amount of inductance which generates a voltage of one volt when the current is changing at a rate of one ampere per second.


title: Inductance

text: All conductors have some inductance, which may have either desirable or detrimental effects in practical electrical devices. The inductance of a circuit depends on the geometry of the current path, and on the magnetic permeability of nearby materials; ferromagnetic materials with a higher permeability like iron near a conductor tend to increase the magnetic field and inductance. Any alteration to a circuit which increases the flux (total magnetic field) through the circuit produced by a given current increases the inductance, because inductance is also equal to the ratio of magnetic flux to current


title: Inductance

text: An inductor is an electrical component consisting of a conductor shaped to increase the magnetic flux, to add inductance to a circuit. Typically it consists of a wire wound into a coil or helix. A coiled wire has a higher inductance than a straight wire of the same length, because the magnetic field lines pass through the circuit multiple times, it has multiple flux linkages. The inductance is proportional to the square of the number of turns in the coil, assuming full flux linkage.


title: Inductance

text: The inductance of a coil can be increased by placing a magnetic core of ferromagnetic material in the hole in the center. The magnetic field of the coil magnetizes the material of the core, aligning its magnetic domains, and the magnetic field of the core adds to that of the coil, increasing the flux through the coil. This is called a ferromagnetic core inductor. A magnetic core can increase the inductance of a coil by thousands of times.


title: Inductance

text: If multiple electric circuits are located close to each other, the magnetic field of one can pass through the other; in this case the circuits are said to be "inductively coupled". Due to Faraday's law of induction, a change in current in one circuit can cause a change in magnetic flux in another circuit and thus induce a voltage in another circuit. The concept of inductance can be generalized in this case by defining the mutual inductance formula_10 of circuit formula_11 and circuit formula_12 as the ratio of voltage induced in circuit formula_12 to the rate of change of current in circuit formula_11. This is the principle behind a "transformer". The property describing the effect of one conductor on itself is more precisely called "self-inductance", and the properties describing the effects of one conductor with changing current on nearby conductors is called "mutual inductance".


title: Inductance

text: If the current through a conductor with inductance is increasing, a voltage formula_15 is induced across the conductor with a polarity that opposes the current—in addition to any voltage drop caused by the conductor's resistance. The charges flowing through the circuit lose potential energy. The energy from the external circuit required to overcome this "potential hill" is stored in the increased magnetic field around the conductor. Therefore, an inductor stores energy in its magnetic field. At any given time formula_16 the power formula_17 flowing into the magnetic field, which is equal to the rate of change of the stored energy formula_18, is the product of the current formula_19 and voltage formula_15 across the conductor


title: Inductance

text: When there is no current, there is no magnetic field and the stored energy is zero. Neglecting resistive losses, the energy formula_18 (measured in joules, in SI) stored by an inductance with a current formula_24 through it is equal to the amount of work required to establish the current through the inductance from zero, and therefore the magnetic field. This is given by:


title: Inductance

text: Inductance is therefore also proportional to the energy stored in the magnetic field for a given current. This energy is stored as long as the current remains constant. If the current decreases, the magnetic field decreases, inducing a voltage in the conductor in the opposite direction, negative at the end through which current enters and positive at the end through which it leaves. This returns stored magnetic energy to the external circuit.


title: Inductance

text: If ferromagnetic materials are located near the conductor, such as in an inductor with a magnetic core, the constant inductance equation above is only valid for linear regions of the magnetic flux, at currents below the level at which the ferromagnetic material saturates, where the inductance is approximately constant. If the magnetic field in the inductor approaches the level at which the core saturates, the inductance begins to change with current, and the integral equation must be used.


title: Inductance

text: When a sinusoidal alternating current (AC) is passing through a linear inductance, the induced back- is also sinusoidal. If the current through the inductance is formula_28, from (1) above the voltage across it is


title: Inductance

text: where formula_30 is the amplitude (peak value) of the sinusoidal current in amperes, formula_31 is the angular frequency of the alternating current, with formula_32 being its frequency in hertz, and formula_1 is the inductance.


title: Inductance

text: Inductive reactance is the opposition of an inductor to an alternating current. It is defined analogously to electrical resistance in a resistor, as the ratio of the amplitude (peak value) of the alternating voltage to current in the component


title: Inductance

text: Reactance has units of ohms. It can be seen that inductive reactance of an inductor increases proportionally with frequency formula_32, so an inductor conducts less current for a given applied AC voltage as the frequency increases. Because the induced voltage is greatest when the current is increasing, the voltage and current waveforms are out of phase; the voltage peaks occur earlier in each cycle than the current peaks. The phase difference between the current and the induced voltage is formula_37 radians or 90 degrees, showing that in an ideal inductor "the current lags the voltage by 90°".


title: Inductance

text: In the most general case, inductance can be calculated from Maxwell's equations. Many important cases can be solved using simplifications. Where high frequency currents are considered, with skin effect, the surface current densities and magnetic field may be obtained by solving the Laplace equation. Where the conductors are thin wires, self-inductance still depends on the wire radius and the distribution of the current in the wire. This current distribution is approximately constant (on the surface or in the volume of the wire) for a wire radius much smaller than other length scales.


title: Inductance

text: As a practical matter, longer wires have more inductance, and thicker wires have less, analogous to their electrical resistance (although the relationships aren't linear, and are different in kind from the relationships that length and diameter bear to resistance).


title: Inductance

text: Separating the wire from the other parts of the circuit introduces some unavoidable error in any formulas’ results. These inductances are often referred to as “partial inductances”, in part to encourage consideration of the other contributions to whole-circuit inductance which are omitted.


title: Inductance

text: The constant 0.75 is just one parameter value among several; different frequency ranges, different shapes, or extremely long wire lengths require a slightly different constant (see below). This result is based on the assumption that the radius formula_41 is much less than the length formula_12, which is the common case for wires and rods. Disks or thick cylinders have slightly different formulas.


title: Inductance

text: For sufficiently high frequencies skin effects cause the interior currents to vanish, leaving only the currents on the surface of the conductor; the inductance for alternating current, formula_47 is then given by a very similar formula:


title: Inductance

text: where the variables formula_12 and formula_41 are the same as above; note the changed constant term now 1, from 0.75 above.


title: Inductance

text: In an example from everyday experience, just one of the conductors of a lamp cord long, made of 18 AWG wire, would only have an inductance of about if stretched out straight.


title: Inductance

text: Currents in the wires need not be equal, though they often are, as in the case of a complete circuit, where one wire is the source and the other the return.


title: Inductance

text: This is the generalized case of the paradigmatic two-loop cylindrical coil carrying a uniform low frequency current; the loops are independent closed circuits that can have different lengths, any orientation in space, and carry different currents. Nonetheless, the error terms, which are not included in the integral are only small if the geometries of the loops are mostly smooth and convex: they do not have too many kinks, sharp corners, coils, crossovers, parallel segments, concave cavities or other topological "close" deformations. A necessary predicate for the reduction of the 3-dimensional manifold integration formula to a double curve integral is that the current paths be filamentary circuits, i.e. thin wires where the radius of the wire is negligible compared to its length.


title: Inductance

text: The mutual inductance by a filamentary circuit formula_51 on a filamentary circuit formula_52 is given by the double integral "Neumann formula"


title: Inductance

text: Stokes' theorem has been used for the 3rd equality step. For the last equality step, we used the retarded potential expression for formula_71 and we ignore the effect of the retarded time (assuming the geometry of the circuits is small enough compared to the wavelength of the current they carry). It is actually an approximation step, and is valid only for local circuits made of thin wires.


title: Inductance

text: Formally, the self-inductance of a wire loop would be given by the above equation with formula_72. However, here formula_73 becomes infinite, leading to a logarithmically divergent integral. This necessitates taking the finite wire radius formula_74 and the distribution of the current in the wire into account. There remains the contribution from the integral over all points and a correction term,


title: Inductance

text: A solenoid is a long, thin coil; i.e., a coil whose length is much greater than its diameter. Under these conditions, and without any magnetic material used, the magnetic flux density formula_88 within the coil is practically constant and is given by


title: Inductance

text: where formula_56 is the magnetic constant, formula_91 the number of turns, formula_2 the current and formula_93 the length of the coil. Ignoring end effects, the total magnetic flux through the coil is obtained by multiplying the flux density formula_88 by the cross-section area formula_95:


title: Inductance

text: When this is combined with the definition of inductance formula_97, it follows that the inductance of a solenoid is given by:


title: Inductance

text: Therefore, for air-core coils, inductance is a function of coil geometry and number of turns, and is independent of current.


title: Inductance

text: Let the inner conductor have radius formula_99 and permeability formula_100, let the dielectric between the inner and outer conductor have permeability formula_101, and let the outer conductor have inner radius formula_102, outer radius formula_103, and permeability formula_56. However, for a typical coaxial line application, we are interested in passing (non-DC) signals at frequencies for which the resistive skin effect cannot be neglected. In most cases, the inner and outer conductor terms are negligible, in which case one may approximate


title: Inductance

text: Most practical air-core inductors are multilayer cylindrical coils with square cross-sections to minimize average distance between turns (circular cross -sections would be better but harder to form).


title: Inductance

text: Many inductors include a magnetic core at the center of or partly surrounding the winding. Over a large enough range these exhibit a nonlinear permeability with effects such as magnetic saturation. Saturation makes the resulting inductance a function of the applied current.


title: Inductance

text: The differential or small-signal inductance, on the other hand, is used in calculating voltage. It is defined as:


title: Inductance

text: The circuit voltage for a nonlinear inductor is obtained via the differential inductance as shown by Faraday's Law and the chain rule of calculus.


title: Inductance

text: Mutual inductance is defined as the ratio between the EMF induced in one loop or coil by the rate of change of current in another loop or coil. Mutual inductance is given the symbol .


title: Inductance

text: The inductance equations above are a consequence of Maxwell's equations. For the important case of electrical circuits consisting of thin wires, the derivation is straightforward.


title: Inductance

text: In a system of formula_109 wire loops, each with one or several wire turns, the flux linkage of loop formula_51, formula_111, is given by


title: Inductance

text: Here formula_113 denotes the number of turns in loop formula_51; formula_115 is the magnetic flux through loop formula_51; and formula_117 are some constants described below. This equation follows from Ampere's law: "magnetic fields and fluxes are linear functions of the currents". By Faraday's law of induction, we have


title: Inductance

text: where formula_119 denotes the voltage induced in circuit formula_51. This agrees with the definition of inductance above if the coefficients formula_117 are identified with the coefficients of inductance. Because the total currents formula_122 contribute to formula_115 it also follows that formula_117 is proportional to the product of turns formula_125.


title: Inductance

text: Multiplying the equation for "v" above with "idt" and summing over "m" gives the energy transferred to the system in the time interval "dt",


title: Inductance

text: This must agree with the change of the magnetic field energy, "W", caused by the currents. The integrability condition


title: Inductance

text: requires "L = L". The inductance matrix, "L", thus is symmetric. The integral of the energy transfer is the magnetic field energy as a function of the currents,


title: Inductance

text: This equation also is a direct consequence of the linearity of Maxwell's equations. It is helpful to associate changing electric currents with a build-up or decrease of magnetic field energy. The corresponding energy transfer requires or generates a voltage. A mechanical analogy in the "K" = 1 case with magnetic field energy (1/2)"Li" is a body with mass "M", velocity "u" and kinetic energy (1/2)"Mu". The rate of change of velocity (current) multiplied with mass (inductance) requires or generates a force (an electrical voltage).


title: Inductance

text: Mutual inductance occurs when the change in current in one inductor induces a voltage in another nearby inductor. It is important as the mechanism by which transformers work, but it can also cause unwanted coupling between conductors in a circuit.


title: Inductance

text: The mutual inductance, formula_129, is also a measure of the coupling between two inductors. The mutual inductance by circuit formula_2 on circuit formula_65 is given by the double integral "Neumann formula", see calculation techniques


title: Inductance

text: Once the mutual inductance, formula_133, is determined, it can be used to predict the behavior of a circuit:


title: Inductance

text: The minus sign arises because of the sense the current formula_135 has been defined in the diagram. With both currents defined going into the dots the sign of formula_133 will be positive (the equation would read with a plus sign instead).


title: Inductance

text: The coupling coefficient is the ratio of the open-circuit actual voltage ratio to the ratio that would be obtained if all the flux coupled from one magnetic circuit to the other. The coupling coefficient is related to mutual inductance and self inductances in the following way. From the two simultaneous equations expressed in the two-port matrix the open-circuit voltage ratio is found to be:


title: Inductance

text: while the ratio if all the flux is coupled is the ratio of the turns, hence the ratio of the square root of the inductances


title: Inductance

text: The coupling coefficient is a convenient way to specify the relationship between a certain orientation of inductors with arbitrary inductance. Most authors define the range as , but some define it as Allowing negative values of formula_11 captures phase inversions of the coil connections and the direction of the windings.


title: Inductance

text: Mutually coupled inductors can be described by any of the two-port network parameter matrix representations. The most direct are the z parameters, which are given by


title: Inductance

text: where formula_142 is the complex frequency variable, formula_143 and formula_144 are the inductances of the primary and secondary coil, respectively, and formula_133 is the mutual inductance between the coils.


title: Inductance

text: Mutually coupled inductors can equivalently be represented by a T-circuit of inductors as shown. If the coupling is strong and the inductors are of unequal values then the series inductor on the step-down side may take on a negative value.


title: Inductance

text: This can be analyzed as a two port network. With the output terminated with some arbitrary impedance, formula_146, the voltage gain, formula_147, is given by,


title: Inductance

text: where formula_11 is the coupling constant and formula_142 is the complex frequency variable, as above.


title: Inductance

text: which is independent of the load impedance. If the inductors are wound on the same core and with the same geometry, then this expression is equal to the turns ratio of the two inductors because inductance is proportional to the square of turns ratio.


title: Inductance

text: Alternatively, two coupled inductors can be modelled using a "π" equivalent circuit with optional ideal transformers at each port. While the circuit is more complicated than a T-circuit, it can be generalized to circuits consisting of more than two coupled inductors. Equivalent circuit elements formula_158, formula_159 have physical meaning, modelling respectively magnetic reluctances of coupling paths and magnetic reluctances of leakage paths. For example, electric currents flowing through these elements correspond to coupling and leakage magnetic fluxes. Ideal transformers normalize all self-inductances to 1 Henry to simplify mathematical formulas.


title: Inductance

text: When a capacitor is connected across one winding of a transformer, making the winding a tuned circuit (resonant circuit) it is called a single-tuned transformer. When a capacitor is connected across each winding, it is called a double tuned transformer. These "resonant transformers" can store oscillating electrical energy similar to a resonant circuit and thus function as a bandpass filter, allowing frequencies near their resonant frequency to pass from the primary to secondary winding, but blocking other frequencies. The amount of mutual inductance between the two windings, together with the Q factor of the circuit, determine the shape of the frequency response curve. The advantage of the double tuned transformer is that it can have a wider bandwidth than a simple tuned circuit. The coupling of double-tuned circuits is described as loose-, critical-, or over-coupled depending on the value of the coupling coefficient formula_11. When two tuned circuits are loosely coupled through mutual inductance, the bandwidth is narrow. As the amount of mutual inductance increases, the bandwidth continues to grow. When the mutual inductance is increased beyond the critical coupling, the peak in the frequency response curve splits into two peaks, and as the coupling is increased the two peaks move further apart. This is known as overcoupling.


title: Inductance

text: Stongly-coupled self-resonant coils can be used for wireless power transfer between devices in the mid range distances (up to two metres). Strong coupling is required for a high percentage of power transferred, which results in peak splitting of the frequency response.


title: Inductance

text: When formula_170, the inductor is referred to as being closely coupled. If in addition, the self-inductances go to infinity, the inductor becomes an ideal transformer. In this case the voltages, currents, and number of turns can be related in the following way:


title: Inductance

text: The power through one inductor is the same as the power through the other. These equations neglect any forcing by current sources or voltage sources.


title: Inductance

text: The table below lists formulas for the self-inductance of various simple shapes made of thin cylindrical conductors (wires). In general these are only accurate if the wire radius formula_74 is much smaller than the dimensions of the shape, and if no ferromagnetic materials are nearby (no magnetic core).


title: Inductance

text: formula_82 is an approximately constant value between 0 and 1 that depends on the distribution of the current in the wire: when the current flows only on the surface of the wire (complete skin effect), when the current is evenly spread over the cross-section of the wire (direct current). For round wires, Rosa (1908) gives a formula equivalent to:


title: Inductance

text: formula_176 is represents small term(s) that have been dropped from the formula, to make it simpler. Read the term as "plus small corrections that vary on the order of formula_177" (see big O notation).


title: Bra

text: A bra, short for brassiere or brassière (, or ; ), is a form-fitting undergarment that is primarily used to support and cover breasts. It can serve a range of other practical and aesthetic purposes, including enhancing or reducing the appearance of breast size and creating cleavage. Bras can also serve specific functions, such as nursing bras to facilitate breastfeeding or sports bras to minimize discomfort during exercise.


title: Bra

text: A typical bra consists of a chest band that wraps around the torso, supporting two breast cups that are held in place by shoulder straps. A bra is usually closed in the back by a hook and eye fastener. However, bras are available in a large range of styles, whose designs can vary widely. Initially, the bra was exclusively an undergarment, but the sports bra has gained acceptance as outerwear, as have fashions that deliberately expose the bra straps.


title: Bra

text: The bra gained widespread adoption in the early twentieth century, when it largely replaced the corset. The first modern bra is attributed to Caresse Crosby, a New York publisher and activist who created the garment in 1910 by using two handkerchiefs and some ribbon. After patenting her design in 1914, she briefly manufactured bras at two-woman factory in Boston before selling her patent to the Warner Brothers Corset Company, which began mass-producing the garment.


title: Bra

text: Bras have gained symbolic significance beyond their mere functionality. Since training bras become standard during puberty, the garment can symbolize a rite of passage to adulthood. However, some feminists have argued that bras sexualize and objectify women's breasts to conform to the male gaze. Surveys suggest that increasing numbers of women are going braless or adopting more comfortable wireless bras and bralettes to achieve more comfort.


title: Bra

text: The term "brassiere", from French "brassière", was used by the "Evening Herald" in Syracuse, New York, in 1893. It gained wider acceptance in 1904 when the DeBevoise Company used it in their advertising copy—although the word is actually French for a child's undershirt. In French, it is called a (literally, "throat-supporter"). It and other early versions resembled a camisole stiffened with boning.


title: Bra

text: "Vogue" magazine first used the term "brassiere" in 1907, and by 1911 the word had entered the "Oxford English Dictionary". On 3 November 1914, the newly formed US patent category for "brassieres" was inaugurated with the first patent issued to Mary Phelps Jacob, later and better known as Caresse Crosby. In the 1930s, "brassiere"/"brassière" was gradually shortened to "bra".


title: Bra

text: Several lingerie and shapewear manufacturers, among them Wonderbra, Frederick's of Hollywood, Agent Provocateur and Victoria's Secret, produce bras that enhance cleavage. As many as 30 kinds of bras are available, including push-up, strapless, bandeau, demicup, sports bra, the minimiser, padded, a T-shirt bra, multiway, plunge, wireless, maternity, seamless, silicone, and stick-on. The history of the brassière is full of myths in which people like Caresse Crosby, Howard Hughes, Herminie Cadolle and Otto Titzling command center stage.


title: Bra

text: Before the spread of brassières, the female bust was encased in corsets and structured garments called "bust improvers", made of boning and lace. The history of corsets indicates they started to go out of fashion by 1917, when metal was needed to make tanks and munitions for World War I, and when 1920s fashions emphasized boyish figures.


title: Bra

text: When corsets became unfashionable, brassières and padding helped to project, display and emphasize the breasts. In 1893, New Yorker Marie Tucek was granted a patent for a "breast supporter", described as a modification of the corset, and was very similar to a modern push-up bra designed to support the breasts. It consisted of a plate made of metal, cardboard or other stiff material shaped to fit against the torso under the breasts, following the contour of the breasts. It was covered with silk, canvas or other cloth, which extended above the plate to form a pocket for each breast. The plate curved around the torso and ended near the armpits.


title: Bra

text: Wearing a garment to support the breasts may date back to ancient Greece. Women wore an "apodesmos", later "stēthodesmē", "mastodesmos" and "mastodeton", all meaning "breast-band", a band of wool or linen that was wrapped across the breasts and tied or pinned at the back. Roman women wore breast-bands during sport, such as those shown on the "Coronation of the Winner" mosaic (also known as the "Bikini mosaic").


title: Bra

text: Fragments of linen textiles found at Lengberg Castle in East Tyrol in Austria dated to between 1440 and 1485 are believed to have been bras. Two of them had cups made from two pieces of linen sewn with fabric that extended to the bottom of the torso with a row of six eyelets for fastening with a lace or string. One had two shoulder straps and was decorated with lace in the cleavage.


title: Bra

text: From the 16th century, the undergarments of wealthier women in the Western world were dominated by the corset, which pushed the breasts upwards. In the later 19th century, clothing designers began experimenting with alternatives, splitting the corset into multiple parts: a girdle-like restraining device for the lower torso, and devices that suspended the breasts from the shoulder to the upper torso.


title: Bra

text: Though the first bra, a linen and lace garment that looks almost exactly like a modern bra, was discovered in an early 15th century collection from Lengberg Castle in Tyrol, Austria, there is no other evidence of any use of bras in the 1400s.


title: Bra

text: In 1914, the first modern bra was patented by New York publisher, activist, and socialite Caresse Crosby (born Mary Phelps Jacob). Frustrated with a whale bone corset that kept popping through a new party dress, she created the bra from two handkerchiefs and some ribbon to create cleavage.


title: Bra

text: Crosby sold bras to friends for one dollar. Soon the two of them founded the Fashion Form Brassière Company, a two-woman factory in Boston. Crosby patented the first bra as "the backless brassière" in 1914. After making a few hundred bras and some orders from department stores, she was persuaded by her husband to close the company. She sold the patent to The Warner Brothers Corset Company for US$1,500. In the next 30 years, Warner Brothers made more than US$15 million from the design.


title: Bra

text: According to Cadolle Lingerie House, Herminie Cadolle, a French inventor, was the first inventor to patent the modern 'brassiere', called the "corselet-gorge", lingerie which separated the upper bra portion from the lower corset, the first step toward the modern bra. An urban legend that the brassière was invented by a man named Otto Titzling ("tit sling") who lost a lawsuit with "Phillip de Brassière" ("fill up the brassière") originated with the 1971 book "Bust-Up: The Uplifting Tale of Otto Titzling and the Development of the Bra" and was propagated in a comedic song from the movie "Beaches".


title: Bra

text: Half the patents filed for the design and manufacture of the bra were created by women. The Dresden-based German, Christine Hardt, patented the first modern brassière in 1899. Sigmund Lindauer from Stuttgart-Bad Cannstatt, Germany, developed a brassière for mass production and patented it in 1912. It was mass-produced by Mechanische Trikotweberei Ludwig Maier und Cie. in Böblingen, Germany. In the United States, Mary Phelps Jacob received a patent in 1914 for the first brassière design that is recognized as the basis for modern bras. Mass production in the early 20th century made the garment widely available to women in the United States, England, Western Europe, and other countries influenced by western fashion. Metal shortages in World War I encouraged the end of the corset.


title: Bra

text: Development of the underwire bra started in the 1930s, though it did not gain widespread popularity until the 1950s, when the end of World War II freed metal for domestic use. Aviator and filmmaker Howard Hughes designed a prototype for an aerodynamic underwire bra for Jane Russell when filming "The Outlaw" in 1941. According to Hughes, the resultant amount was "the length of the actual cleavage is five and one-quarter inches." Bras in 1940s left a substantial amount of fabric in the center, thus creating a separation of breasts instead of the pushed-together cleavage of today. Frederick Mellinger of Frederick's of Hollywood created the first padded bra in 1947, followed by an early push-up bra a year later (dubbed "The Rising Star").


title: Bra

text: A padded bra adds material (foam, silicone, gel, air, fluid etc.) to the cups to help the breasts look fuller. There are different designs, from a slight lift to a highly pushed-up effect, that provide coverage and support, hides nipples, add shape to breasts that are far apart and adds comfort. Graduated padding uses more padding at the bottom of the cups that gradually tapers off towards the top. There also are semi-padded bras that suits deep neck dresses. With the advent of padded bras, sales of removable pads took a plunge, though some padded bras also have removable inserts. Actress Julia Roberts was required to wear a custom made silicone gel filled bra for the movie "Erin Brockovich" in order to increase her cleavage.


title: Bra

text: Brassières were initially manufactured by small production companies and supplied to retailers. The term "cup" was not used until 1916, and manufacturers relied on stretchable cups to accommodate different sized breasts. Women with larger or sagging breasts had the choice of long-line bras, built-up backs, wedge-shaped inserts between the cups, wider straps, Lastex, firm bands under the cup, and light boning.


title: Bra

text: In October 1932, the S.H. Camp and Company correlated the size and pendulousness of breasts to letters A through D. Camp's advertising featured letter-labeled profiles of breasts in the February 1933 issue of "Corset and Underwear Review". In 1937, Warner began to feature cup sizing in its products. Adjustable bands were introduced using multiple hook and eye closures in the 1930s. By the time World War II ended, most fashion-conscious women in Europe and North America were wearing brassière, and women in Asia, Africa, and Latin America began to adopt it.


title: Bra

text: In fall 1963 and spring 1964, the Western fashion trends were dominated by plunging necklines, while the movie goers were charmed by movies like "Tom Jones" that portrayed "aggressive cleavages". Lingerie and Shapewear manufacturers like Warner Brothers, Gossard, Formfit, and Bali took the opportunity to market plunge bras. A plunge bra covers the nipples and bottom of the breasts while leaving the top part bare making it suitable for low-cut tops and deep V-necks. It also has a lower, shorter and narrower center gore that maintains support while increasing cleavage by allowing the gore to drop several inches below the middle of the breasts. Plunge bras comes in different depths that provide great cleavage. Like a push up bra these have some padding and provide support, as well as to help push the breasts together and create cleavage. Bali and Vassarette also marketed lace bras that maximized cleavage.


title: Bra

text: The first push-up bra was created in 1964 by Canadian Louise Poirier and patented for Wonderbra (trademarked in 1935), then owned by Canadelle, a Canadian lingerie company in 1971. A push up bra is designed to press the breasts upwards and closer together to give a fuller appearance with help of padded cups, differing from other padded bras in location of the pads. It leaves the upper and inner area of breasts uncovered adding more cleavage. These are available in many designs and every size starting from A to E. Most of the push-up bras have underwires for added lift and support, while the padding is commonly made of foam.


title: Bra

text: The Wonderbra brand was acquired, in 1994, by Sara Lee Corporation and, since 2006, licensed to HanesBrands Inc and Sun Capital for different markets. It had 54 design elements, including a three-part cup, underwires, a precision-angled back, rigid straps, and removable "cookies". When the push-up plunge bra first appeared in the US market one Wonderbra sold every 15 seconds, driving a first year sale of US$120 million. The bra became one of the most complex pieces of lingerie ever created.


title: Bra

text: In 1994, supermodel Eva Herzigova's cleavage photographed by Ellen von Unwerth for Wonderbra's controversial advertising campaign "Hello Boys" helped shape the ideal of women, an experience Herzigova described as "empowering". In 1999, the advertising poster was placed at 10th position in the Poster of the Century competition compiled by trade magazine Campaign. In 2011, it was voted the top advertising campaign of all time in a poll by Outdoor Media Centre, and advertising and marketing portal, and was featured in an exhibition at the Victoria and Albert Museum. It helped to bring the brand into forefront of the competition for cleavage after 30 years of relative obscurity. On the first Friday of every April in South Africa, brassière marketer Wonderbra sponsors a National Cleavage Day.


title: Bra

text: America's largest lingerie retailer Victoria's Secret was launched by Roy Raymond, a Stanford alumnus, in San Francisco in late 1970s with a similar appeal. Victoria's Secret Angels held its first fashion show at Plaza Hotel in New York in 1995. Even traditional brands, who were producing 1950s style pointy-cups, low-backs, low-fronts and no-straps, like Maidenform joined the competition in 1995. In 1999 the event was first webcast. By 2001, the event was being aired on network television with 12 million viewers for the first broadcast. Other lingerie manufacturers like Frederick's of Hollywood and Agent Provocateur also joined the competition by that time, with the former introducing a design called Hollywood Extreme Cleavage Bra that helped give the impression of a spherical cleavage like augmented breasts that was popularized by stars like Pamela Anderson.


title: Bra

text: The underwire bra utilizes a wire sewn into the bra fabric and under each cup, from the center gore to under the wearer's armpit. It helps to lift, separate, shape, and support the breasts. These bras use a thin strip of metal, plastic or resin, usually with a nylon coating at both ends. Some underwire bra styles also come in soft cup versions. Underwire bras accounted for 60% of the United Kingdom bra market in 2000 and 70% in 2005. About 70% of women who wear bras wear a steel underwire bra according to underwear manufacturer industries of New York in 2009. In 2001, 70% (350 million) of the bras sold in the United States were underwire bras. In 2005, underwire bras were the fastest growing segment of the market. There has been complaints that underwire bras restrict the flow of blood and lymph fluid around the breasts preventing drainage of toxins, though there has been no evidence of that.


title: Bra

text: In the next decade, particularly during the COVID-19 lockdowns, bralettes and soft bras started replacing underwired and padded bras, sometimes also serving as an outerwear. At the same time popularity of brands like Victoria's Secret decreased significantly. Because, according to Sarah Shotton, creative director of Agent Provocateur, "Now it's about the athletic body, health and wellbeing", than "about the male gaze," while according to independent lingerie designer Araks Yeramyan "It was #MeToo that catapulted the bralette movement into what it is today." Some bralettes still provide plunging designs, light padding, bottom support or significant cleavage.


title: Bra

text: Mass-produced bras are manufactured to fit a prototypical woman standing with both arms at her sides. The design assumes that both breasts are equally sized and symmetrical. Manufacturing a well-fitting bra is a challenge since the garment is supposed to be form-fitting but women's breasts may sag, vary in volume, width, height, shape, and position on the chest. Manufacturers make standard bra sizes that provide a "close" fit, however even a woman with accurate measurements can have a difficult time finding a correctly fitted bra because of the variations in sizes between different manufacturers. Some manufacturers create "vanity sizes" and deliberately mis-state the size of their bras in an attempt to persuade women that they are slimmer and more buxom.


title: Bra

text: A bra is one of the most complicated garments to make. A typical design has between 20 and 48 parts, including the band, gore, side panel, cup, apex, neckline, underwire, strap, ring, slider, strap join, and closure. Bras are built on a square frame model. Lingerie designer Chantal Thomass said,


title: Bra

text: The primary component offering the most support is a chest band that wraps around the torso. It supports two cups that are usually held in place by two shoulder straps. The chest band is usually closed in the back by a hook and eye fastener, but smaller busted models may be fastened at the front. Sleep bras or athletic bras do not have fasteners and are pulled on over the head and breasts. The section between the cups is called a gore. The section under the armpit where the band joins the cups is called the "back wing".


title: Bra

text: Bra components, including the cup top and bottom (if seamed), the central, side and back panels, and straps, are cut to manufacturer's specifications. Many layers of fabric may be cut at the same time using computer-controlled lasers or bandsaw shearing devices. The pieces are assembled by piece workers using industrial sewing machines or automated machines. Coated metal hooks and eyes are sewn in by machine and heat processed or ironed into the back ends of the band and a tag or label is attached or printed onto the bra itself. The completed bras are folded (mechanically or manually), and packaged for shipment.


title: Bra

text: The chest band and cups, not the shoulder straps, are designed to support the weight of women's breasts. Strapless bras rely on an underwire and additional seaming and stiffening panels to support them. The shoulder straps of some sports bras cross over at the back to take the pressure off the shoulders when arms are raised. Manufacturers continually experiment with proprietary frame designs. For example, the Playtex "18-Hour Bra" model utilizes an M-Frame design.


title: Bra

text: Bras were originally made of linen, cotton broadcloth, and twill weaves and sewn using flat-felled or bias-tape seams. They are now made of a variety of materials, including Tricot, Spandex, Spanette, Latex, microfiber, satin, Jacquard, foam, mesh, and lace, which are blended to achieve specific purposes. Spandex, a synthetic fiber with built-in "stretch memory", can be blended with cotton, polyester, or nylon. Mesh is a high-tech synthetic composed of ultra-fine filaments that are tightly knit for smoothness.


title: Bra

text: Sixty to seventy per cent of bras sold in the UK and US have underwired cups. The underwire is made of metal, plastic, or resin. Said the antecedents for underwire in bras date to at least 1893, when Marie Tucek of New York City patented a "breast supporter", a sort of early push-up bra made of either metal or cardboard and then covered with fabric. Underwire is built around the perimeter of the cup where it attaches to the band, increasing its rigidity to improve support, lift, and separation.


title: Bra

text: By the late 1970s, wire-free bras were emerging both at Hanky Panky and at Hanro in Switzerland. Cosabella in Italy and in France followed in the 1980s, as did Eberjey in the 1990s. Others use padding or shaping materials to enhance bust size or cleavage.


title: Bra

text: In most countries, bras come in a band and cup size, such as 34C; 34 is the chest band, or the measurement around the torso directly underneath the breasts, and C is the cup size, which refers to the volume of the breasts. Most bras are offered in 36 sizes; the Triumph "Doreen" comes in 67 sizes, up to 46J.


title: Bra

text: The cup size varies depending on the band size. A D cup on a 38 band is larger in volume than a D cup on a 34 band, as the volume of a woman's breast increases as her chest band dimension increases. In countries that have adopted the European EN 13402 dress-size standard, the measurement is rounded to the nearest multiple of .


title: Bra

text: International manufacturing standards and measurement systems vary widely. Bras are designed for an ideal body, but women's anatomy vary widely. Ten percent of women's breasts are asymmetrical, with the left breast being larger in 62 percent of cases. One woman's breasts may be ptotic and widely spaced, another's might be centered closely on the chest, upright, and very full. As a result, finding a correctly fitting bra is extremely difficult. When women find a bra that appears to fit, they tend to stay with that size, even though they may lose and gain weight.


title: Bra

text: In a survey in the United Kingdom, 60 per cent of over 2,000 women between the ages of 16 to 75 said they had had a bra fitting, and 99 per cent said that fit was the least important factor when selecting a bra. Increased publicity about the issue of poorly fitted bras has increased the number of women seeking a fitting. The UK retailer Marks & Spencer stated that about 8,000 women are fitted for bras in their stores weekly. Despite this, about 80–85 percent of women still wear the wrong bra size.


title: Bra

text: Bra experts recommend professional bra fittings from the lingerie department of a clothing store or a specialty lingerie store, especially for cup sizes D or larger, and particularly if there has been significant weight gain or loss, or if the wearer is continually adjusting her bra. Women in the UK change their bra size on average six times over their lifetimes.


title: Bra

text: Signs of a loose bra band include the band riding up the back. If the band causes flesh to spill over the edges, it is too small. A woman can test whether a bra band is too tight or loose by reversing the bra on her torso so that the cups are in the back and then check for fit and comfort. Experts suggest that women choose a band size that fits using the outermost set of hooks. This allows the wearer to use the tighter hooks as the bra stretches during its lifetime.


title: Bra

text: Bras may be designed to enhance a woman's breast size, or to create cleavage, or for other aesthetic, fashion, or more practical considerations. Nursing bras are designed to aid breastfeeding. Compression bras, such as sports bras, push against and minimize breast movement, whereas encapsulation bras have cups for support. Breast support may be built into some swimsuits, camisoles and dresses. Cancer bras are designed specifically for breast cancer patients who have undergone a mastectomy. The styles provide post-surgical support, and some include pads or pockets for stuffing.


title: Bra

text: Bras come in a variety of styles, including backless, balconette, convertible, shelf, full cup, full coverage bra, demi-cup, minimizing, padded, plunge, lounge bra, posture, push-up, racerback, sheer, strapless, T-shirt, underwire, unlined, and soft cup.


title: Bra

text: Women's choices about what bra to wear are consciously and unconsciously affected by social perceptions of the ideal female body shape, which changes over time. As lingerie, women wear bras for sex appeal. Bras can also be used to make a social statement as evidenced by Jean-Paul Gaultier's designs and the cone-shaped bra Madonna wore outside her clothing on her Blond Ambition World Tour.


title: Bra

text: During the 1940s and 1950s, the sweater girl became fashionable, supported by a "bullet bra" (known also as a torpedo or cone bra) as worn by Jane Russell and Patti Page.


title: Bra

text: As outerwear, bras in the form of bikini tops in the 1950s became an acceptable public display. During the 1960s, designers and manufacturers introduced padded and underwire bras. After the Miss America protest in September 1968, manufacturers were concerned that women would stop wearing bras. In response, many altered their marketing and claimed that wearing their bra was like "not wearing a bra". In the 1970s women sought more comfortable and natural-looking bras.


title: Bra

text: In the late 1990s larger breasts became more fashionable in England. Iris Marion Young described preferences in the United States in 1990: "round, sitting high on the chest, large but not bulbous, with the look of firmness." This is regarded as contradictory in several ways.


title: Bra

text: Victoria's Secret commissions a fantasy bra every autumn. In 2003 it hired the jeweller Mouawad to design one containing more than 2500 carats of diamonds and sapphires; valued at US$10 million, it was the world's most valuable bra at the time.


title: Bra

text: Sports bras were invented in 1975. Women wore them under other clothing for the next 25 years. But on 10 July 1999, Brandi Chastain scored the fifth kick in the penalty shootout to give the United States the win over China in the final game of the 1999 FIFA Women's World Cup Final. In celebration, she spontaneously whipped off her jersey, exposing her sports bra. Her act is regarded by some as a historical event that boosted wearing sports bras alone. From that point forward, sports bras were increasingly worn as outerwear.


title: Bra

text: Madonna was one of the first to start showing her bra straps, in the late 1980s. A corset she wore as outerwear during her 1990 Blond Ambition World Tour sold for US$52,000 in 2012 at the Christie's Pop Culture auction in London. Versace's autumn 2013 couture collection featured fashions that were open in the front, revealing underwire bras. It became fashionable from the early 1990s to wear clothing that showed bra straps.


title: Bra

text: Wearing clothes that reveal the bra or straps became so common that "Cosmopolitan" created guidelines in 2012 on how to expose them. Advice included avoiding plain, flesh-toned, smooth-cup bras, so that the exposure does not appear accidental; making sure the bra is in good condition; and wearing a style that either matches the colour of the outerwear or is dramatically different.


title: Bra

text: While a few women have a medical and surgical need to wear a brassiere, informal surveys have found that many women began wearing bras to be fashionable, to conform to social or maternal pressure, or for physical support. Very few cited comfort as the reason. In fact, many women experience so much discomfort that they remove their bra as soon as they can.


title: Bra

text: In Western society, since the 1960s, there has been a slow but steady trend towards bralessness among a number of women, especially millennials, who have expressed opposition to and are giving up wearing bras. Being seen in public while not wearing a bra has become more acceptable over the past 6 decades, encouraging more women to go without. In 2016, "Allure" magazine fashion director Rachael Wang wrote, "Going braless is as old as feminism but it seems to be bubbling to the surface more recently as a direct response to Third Wave moments like #freethenipple hashtag campaign, increased trans-visibility like Caitlyn Jenner's "Vanity Fair" cover ... and Lena Dunham's show "Girls" (which features young women often without bras)."


title: Bra

text: In an online survey for "All You" magazine in 2013, 25 percent of women reported that they do not wear a bra every day. Surveys have reported that 5–25 per cent of Western women do not wear a bra.


title: Bra

text: A National No Bra Day was first observed in the United States on 9 July 2011. Women posted on Twitter about the relief they felt when taking off their bra. More than 250,000 people expressed an interest in "attending" the day on a Facebook page. No Bra Day is now observed internationally on 13 October.


title: Bra

text: A Harris Poll commissioned by "Playtex" asked more than 1,000 women what they like in a bra. Among the respondents, 67 per cent said they prefer wearing a bra to going braless, while 85 per cent wanted to wear a "shape-enhancing bra that feels like nothing at all." They were split as regards underwire bras: 49 per cent said they prefer underwire bras, the same percentage as those who said they prefer wireless bras. According to underwire manufacturer S & S Industries of New York, who supply bras to Victoria's Secret, Bali, Warner's, Playtex, Vanity Fair, and other labels, about 70 per cent of bra-wearing women wear underwire bras.


title: Bra

text: COVID-19 lockdowns led to more women adopting wireless bras and bralettes for comfort. The company Knix, which manufactures exclusively soft-cup bras, reported a 100 percent increase in sales between January 2020 and January 2021. “I don’t think women are going to want to go back to wearing their regular everyday bras,” stated the chief product officer for Lululemon.


title: Bra

text: Bras are not universally worn around the world; in some developing countries bras may cost up to 10–30 hours of a woman's wages, making them unaffordable to most of the population. , women in Fiji needed to pay up to a week's wages for a new bra. Bras are highly prized at second-hand markets in West Africa. The Uplift Project provides recycled bras to women in developing countries. Since 2005 they have shipped 330,000, including to Fiji, Vanuatu, Tonga, and Cambodia.


title: Bra

text: In 2009 Somalia's hard-line Islamic group Al-Shabaab forced women to shake their breasts at gunpoint to see if they were wearing bras, which they called "un-Islamic". A resident of Mogadishu whose daughters were whipped said, "The Islamists say a woman's chest should be firm naturally, or flat."


title: Bra

text: Consumers spend around $16 billion a year worldwide on bras. In the US during 2012, women owned an average of nine bras and wore six on a regular basis. That increased from 2006, when the average American woman owned six, one of which was strapless, and one in a colour other than white. British women in a 2009 survey reported that they owned an average of 16 bras.


title: Bra

text: The average bra size among North American women has changed from 34B in 1983 to a 34DD in 2012–2013, and from 36C in 2013 to 36DD in the UK during 2014–2015. The change in bra size has been linked to growing obesity rates, breast implants, increased birth control usage, estrogen mimicking pollutants, the availability of a larger selection of bras, and women wearing better fitting bras.


title: Bra

text: Bras are made in Asian countries, including Sri Lanka, India, and China. While there has been some social pressure from the anti-sweatshop and anti-globalization movements on manufacturers to reduce use of sweatshop labour, most major apparel manufacturers rely on them directly and indirectly. Prior to 2005, a trade agreement limited textile imports to the European Union and the US. China was exporting US$33.9 billion in textiles and clothing each year to the EU and the US. When those quotas expired on 1 January 2005, the so-called Bra Wars began. Within six months, China shipped 30 million more bras to the two markets: 33 per cent more to the US and 63 per cent more to the EU. , an average bra cost £29.80. , Africa imported US$107 million worth of bras, with South Africa accounting for 40 per cent. Morocco was second and Nigeria third, while Mauritius topped purchasing on a per capita basis.


title: Bra

text: In countries where labour costs are low, bras that cost US$5–7 to manufacture sell for US$50 or more in American retail stores. , female garment workers in Sri Lanka earned about US$2.20 per day. Similarly, Honduran garment factory workers in 2003 were paid US$0.24 for each $50 Sean John sweatshirt they made, less than one-half of one per cent of the retail price. In 2009, residents in the textile manufacturing city of Gurao in the Guangdong province of China made more than 200 million bras. Children were employed to assemble bras and were paid 0.30 yuan for every 100 bra straps they helped assemble. In one day they could earn 20 to 30 yuan.


title: Bra

text: In 1968 at the feminist Miss America protest, protesters symbolically threw a number of feminine products into a "Freedom Trash Can". These included bras, which were among items the protesters called "instruments of female torture" and accoutrements of what they perceived to be enforced femininity. A local news story in the Atlantic City "Press" erroneously reported that "the bras, girdles, falsies, curlers, and copies of popular women's magazines burned in the 'Freedom Trash Can'". Individuals who were present said that no one burned a bra nor did anyone take off her bra. However, a female reporter (Lindsy Van Gelder) covering the protest drew an analogy between the feminist protesters and Vietnam War protesters who burned their draft cards, and the parallel between protesters burning their draft cards and women burning their bras was encouraged by some organizers including Robin Morgan. "The media picked up on the bra part", Carol Hanisch said later. "I often say that if they had called us 'girdle burners,' every woman in America would have run to join us."


title: Bra

text: Feminism and "bra-burning" became linked in popular culture. The analogous term "jockstrap-burning" has since been coined as a reference to masculism. While feminist women did not literally burn their bras, some stopped wearing them in protest. The feminist author Bonnie J. Dow has suggested that the association between feminism and bra-burning was encouraged by individuals who opposed the feminist movement. "Bra-burning" created an image that women weren't really seeking freedom from sexism, but were attempting to assert themselves as sexual beings. This might lead individuals to believe, as Susan J. Douglas wrote, that the women were merely trying to be "trendy, and to attract men." Some feminist activists believe that anti-feminists use the bra burning myth and the subject of going braless to trivialize what the protesters were trying to accomplish at the feminist 1968 Miss America protest and the feminist movement in general.


title: Bra

text: The trope of feminists burning their bras was anticipated by an earlier generation of feminists who called for burning corsets as a step toward liberation. In 1873, American novelist Elizabeth Stuart Phelps Ward wrote:


title: Bra

text: Some feminists began arguing in the 1960s and 1970s that the bra was an example of how women's clothing shaped and even deformed women's bodies to male expectations. In 1964, Professor Lisa Jardine described her dinner with Australian writer and public intellectual Germaine Greer during a formal college dinner in Newnham College, Cambridge:


title: Bra

text: Germaine Greer's book "The Female Eunuch" (1970) became associated with the anti-bra movement because she pointed out how restrictive and uncomfortable a bra could be. "Bras are a ludicrous invention," she wrote, "but if you make bralessness a rule, you're just subjecting yourself to yet another repression."


title: Bra

text: Susan Brownmiller in her book "Femininity" (1984) took the position that women without bras shock and anger men because men "implicitly think that they own breasts and that only they should remove bras."


title: Bra

text: The feminist author Iris Marion Young wrote in 2005 that the bra "serves as a barrier to touch" and that a braless woman is "deobjectified", eliminating the "hard, pointy look that phallic culture posits as the norm." Without a bra, in her view, women's breasts are not consistently shaped objects but change as the woman moves, reflecting the natural body. Other feminist anti-bra arguments from Young in 2005 include that training bras are used to indoctrinate girls into thinking about their breasts as sexual objects and to accentuate their sexuality. Young also wrote in 2007 that, in American culture, breasts are subject to patriarchal American media-dominated culture [that] objectifies breasts before such a distancing glance that freezes and masters." The academic Wendy Burns-Ardolino wrote in 2007 that women's decision to wear bras is mediated by the "male gaze".


title: Bra

text: Some women experience generalized breast discomfort and tenderness from fibrocystic breast changes, and their breast tissue is often described as "lumpy", "rope-like", or "doughy". Doctors often recommend that women wear a well-fitted, supportive bra to help resolve the symptoms.


title: Bra

text: Biomechanical studies have demonstrated that, depending on the activity and the size of a woman's breast, when she walks or runs braless, her breasts may move up and down by or more, and also oscillate side to side.


title: Bra

text: Researchers have also found that as women's breast size increased, they took part in less physical activity, especially vigorous exercise. Few very-large-breasted women jogged, for example. To avoid exercise-related discomfort and pain, medical experts suggest women wear a well-fitted sports bra during activity.


title: Bra

text: Women sometimes wear bras because they mistakenly believe they prevent breasts from sagging (ptosis) as they get older. Physicians, lingerie retailers, teenagers, and adult women used to believe that bras were medically required to support breasts. In a 1952 article in "Parents' Magazine", Frank H. Crowell erroneously reported that it was important for teen girls to begin wearing bras early. According to Crowell, this would prevent sagging breasts, stretched blood vessels, and poor circulation later on.


title: Bra

text: This belief was based on the false idea that breasts cannot anatomically support themselves. A 2013 study by Jean-Denis Rouillon said that wearing a bra may actually weaken supportive tissue. Bra manufacturers are careful to claim that bras only affect the shape of breasts while they are being worn. The key factors influencing breast ptosis over a woman's lifetime are cigarette smoking, her number of pregnancies, gravity, higher body mass index, larger bra cup size, and significant weight gain and loss.


title: The Gray Man (novel)

text: The Gray Man is the debut novel by Mark Greaney, first published in 2009 by Jove Books. It is also the first novel to feature the Gray Man, freelance assassin and former CIA operative Court Gentry.


title: The Gray Man (novel)

text: The novel follows Gentry on a mission across Europe to rescue his handler, Sir Donald Fitzroy, and his family in Normandy, France, from Lloyd, a member of a gigantic French corporation and former CIA officer who wants Gentry terminated in order to shepherd a billion-dollar deal for oil interests in Nigeria, where its president, in turn, wants Gentry dead for the assassination of his brother.


title: The Gray Man (novel)

text: There have been several attempts to turn the novel into a film, initially with Christopher McQuarrie attached to direct in 2016. After that version fell through, the project lay dormant until July 2020, when Netflix announced their plans to adapt it. Eventually, it was directed by Joe and Anthony Russo, with Joe Russo also writing the screenplay, and Christopher Markus and Stephen McFeely performing a re-write. Starring Ryan Gosling, Chris Evans, Ana de Armas, Dhanush, Wagner Moura, Julia Butters, and Jessica Henwick, filming commenced in 2021 on a $200 million budget. It was eventually released on July 22, 2022.


title: Secular humanism

text: Secular humanism is a philosophy, belief system or life stance that embraces human reason, secular ethics, and philosophical naturalism while specifically rejecting religious dogma, supernaturalism, and superstition as the basis of morality and decision making.


title: Secular humanism

text: Secular humanism posits that human beings are capable of being ethical and moral without religion or belief in a deity. It does not, however, assume that humans are either inherently good or evil, nor does it present humans as being superior to nature. Rather, the humanist life stance emphasizes the unique responsibility facing humanity and the ethical consequences of human decisions. Fundamental to the concept of secular humanism is the strongly held viewpoint that ideology—be it religious or political—must be thoroughly examined by each individual and not simply accepted or rejected on faith. Along with this, an essential part of secular humanism is a continually adapting search for truth, primarily through science and philosophy. Many secular humanists derive their moral codes from a philosophy of utilitarianism, ethical naturalism, or evolutionary ethics, and some advocate a science of morality.


title: Secular humanism

text: Humanists International, founded by Julian Huxley and Jaap van Praag, is the world union of more than one hundred humanist, rationalist, irreligious, atheist, Bright, secular, Ethical Culture, and freethought organizations in more than 40 countries. The "Happy Human" is recognized as the official symbol of humanism internationally, used by secular humanist organizations in every part of the world.


title: Secular humanism

text: The meaning of the phrase "secular humanism" has evolved over time. The phrase has been used since at least the 1930s by Anglican priests, and in 1943, the then Archbishop of Canterbury, William Temple, was reported as warning that the "Christian tradition... was in danger of being undermined by a 'Secular Humanism' which hoped to retain Christian values without Christian faith." During the 1960s and 1970s the term was embraced by some humanists who considered themselves anti-religious, as well as those who, although not critical of religion in its various guises, preferred a non-religious approach. The release in 1980 of "A Secular Humanist Declaration" by the newly formed Council for Democratic and Secular Humanism (CODESH, later the Council for Secular Humanism, which with CSICOP in 1991 jointly formed the Center for Inquiry and in 2015 both ceased separate operations, becoming CFI programs) gave secular humanism an organisational identity within the United States; but no overall organisation involved currently uses a name featuring "secular humanism".


title: Secular humanism

text: However, many adherents of the approach reject the use of the word "secular" as obfuscating and confusing, and consider that the term "secular humanism" has been "demonized by the religious right... All too often secular humanism is reduced to a sterile outlook consisting of little more than secularism slightly broadened by academic ethics. This kind of 'hyphenated humanism' easily becomes more about the adjective than its referent". Adherents of this view, including Humanists International and the American Humanist Association, consider that the unmodified but capitalized word Humanism should be used. The endorsement by the International Humanist and Ethical Union (IHEU) of the capitalization of the word "Humanism", and the dropping of any adjective such as "secular", is quite recent. The American Humanist Association began to adopt this view in 1973, and the IHEU formally endorsed the position in 1989. In 2002 the IHEU General Assembly unanimously adopted the Amsterdam Declaration, which represents the official defining statement of World Humanism for Humanists. This declaration makes exclusive use of capitalized "Humanist" and "Humanism", which is consistent with IHEU's general practice and recommendations for promoting a unified Humanist identity. To further promote Humanist identity, these words are also free of any adjectives, as recommended by prominent members of IHEU. Such usage is not universal among IHEU member organizations, though most of them do observe these conventions.


title: Secular humanism

text: Historical use of the term humanism (reflected in some current academic usage), is related to the writings of pre-Socratic philosophers. These writings were lost to European societies until Renaissance scholars rediscovered them through Muslim sources and translated them from Arabic into European languages. Thus the term humanist can mean a humanities scholar, as well as refer to The Enlightenment/ Renaissance intellectuals, and those who have agreement with the pre-Socratics, as distinct from secular humanists.


title: Secular humanism

text: In 1851 George Holyoake coined the term "secularism" to describe "a form of opinion which concerns itself only with questions, the issues of which can be tested by the experience of this life".


title: Secular humanism

text: The modern secular movement coalesced around Holyoake, Charles Bradlaugh and their intellectual circle. The first secular society, the Leicester Secular Society, dates from 1851. Similar regional societies came together to form the National Secular Society in 1866.


title: Secular humanism

text: Holyoake's secularism was strongly influenced by Auguste Comte, the founder of positivism and of modern sociology. Comte believed human history would progress in a "law of three stages" from a theological phase, to the "metaphysical", toward a fully rational "positivist" society. In later life, Comte had attempted to introduce a "religion of humanity" in light of growing anti-religious sentiment and social malaise in revolutionary France. This religion would necessarily fulfil the functional, cohesive role that supernatural religion once served.


title: Secular humanism

text: Although Comte's religious movement was unsuccessful in France, the positivist philosophy of science itself played a major role in the proliferation of secular organizations in the 19th century in England. Richard Congreve visited Paris shortly after the French Revolution of 1848 where he met Auguste Comte and was heavily influenced by his positivist system. He founded the London Positivist Society in 1867, which attracted Frederic Harrison, Edward Spencer Beesly, Vernon Lushington, and James Cotter Morison amongst others.


title: Secular humanism

text: In 1878, the Society established the Church of Humanity under Congreve's direction. There they introduced sacraments of the Religion of Humanity and published a co-operative translation of Comte's Positive Polity. When Congreve repudiated their Paris co-religionists in 1878, Beesly, Harrison, Bridges, and others formed their own positivist society, with Beesly as president, and opened a rival centre, Newton Hall, in a courtyard off Fleet Street.


title: Secular humanism

text: The New York City version of the church was established by English immigrant Henry Edger. The American version of the "Church of Humanity" was largely modeled on the English church. Like the English version it wasn't atheistic and had sermons and sacramental rites. At times the services included readings from conventional religious works like the Book of Isaiah. It was not as significant as the church in England, but did include several educated people.


title: Secular humanism

text: Another important precursor was the ethical movement of the 19th century. The South Place Ethical Society was founded in 1793 as the South Place Chapel on Finsbury Square, on the edge of the City of London, and in the early nineteenth century was known as "a radical gathering-place". At that point it was a Unitarian chapel, and that movement, like Quakers, supported female equality. Under the leadership of Reverend William Johnson Fox, it lent its pulpit to activists such as Anna Wheeler, one of the first women to campaign for feminism at public meetings in England, who spoke in 1829 on "rights of women". In later decades, the chapel changed its name to the South Place Ethical Society, now the Conway Hall Ethical Society. Today Conway Hall explicitly identifies itself as a humanist organisation, albeit one primarily focused on concerts, events, and the maintenance of its humanist library and archives. It bills itself as "The landmark of London’s independent intellectual, political and cultural life."


title: Secular humanism

text: In America, the ethical movement was propounded by Felix Adler, who established the New York Society for Ethical Culture in 1877. By 1886, similar societies had sprouted up in Philadelphia, Chicago and St. Louis.


title: Secular humanism

text: In effect, the movement responded to the religious crisis of the time by replacing theology with unadulterated morality. It aimed to "disentangle moral ideas from religious doctrines, metaphysical systems, and ethical theories, and to make them an independent force in personal life and social relations." Adler was also particularly critical of the religious emphasis on creed, believing it to be the source of sectarian bigotry. He therefore attempted to provide a universal fellowship devoid of ritual and ceremony, for those who would otherwise be divided by creeds. Although the organisation was overwhelmingly made up of (and entirely led by) atheists, and were many of the same people as in the secular movement, Ethical organisations at that time publicly avoided debate about religious beliefs, publicly advocating neither atheism nor theism, agnosticism nor deism, instead stressing "deed without creed" and a "purely human basis" for morality.


title: Secular humanism

text: The first ethical society along these lines in Britain was founded in 1886. By 1896 the four London societies formed the Union of Ethical Societies, and between 1905 and 1910 there were over fifty societies in Great Britain, seventeen of which were affiliated with the Union. The Union of Ethical Societies would later incorporate as the Ethical Union, a registered charity, in 1928. Under the leadership of Harold Blackham, it renamed itself the British Humanist Association in 1967. It became Humanists UK in 2017.


title: Secular humanism

text: In the 1930s, "humanism" was generally used in a religious sense by the Ethical movement in the United States, and not much favoured among the non-religious in Britain. Yet "it was from the Ethical movement that the non-religious philosophical sense of "Humanism" gradually emerged in Britain, and it was from the convergence of the Ethical and Rationalist movements that this sense of "Humanism" eventually prevailed throughout the Freethought movement".


title: Secular humanism

text: As an organised movement in its own right, humanism emerged from vibrant non-religious movements of the 18th and 19th centuries such as the Owenites, Ethical Culture, the freethinkers, secularists, and positivists, as well as a few non-religious radical Unitarian congregations. The first Humanist Manifesto announced the humanist movement by that name to the public in 1933, following work at the University of Chicago across the 1920s. The American Humanist Association was incorporated as an Illinois non-profit organization in 1943. The International Humanist and Ethical Union was founded in 1952, when a gathering of world Humanists met under the leadership of Sir Julian Huxley. The British Humanist Association took that name in 1967, but had developed from the Union of Ethical Societies which had been founded by Stanton Coit in 1896.


title: Secular humanism

text: The original signers of the first Humanist Manifesto of 1933, declared themselves to be religious humanists. Because, in their view, traditional religions were failing to meet the needs of their day, the signers of 1933 declared it a necessity to establish a religion that was a dynamic force to meet the needs of the day. However, this "religion" did not profess a belief in any god. Since then two additional Manifestos were written to replace the first. In the Preface of Humanist Manifesto II, in 1973, the authors Paul Kurtz and Edwin H. Wilson assert that faith and knowledge are required for a hopeful vision for the future. Manifesto II references a section on Religion and states traditional religion renders a disservice to humanity. Manifesto II recognizes the following groups to be part of their naturalistic philosophy: "scientific", "ethical", "democratic", "religious", and "Marxist" humanism.


title: Secular humanism

text: In 2002, the IHEU General Assembly unanimously adopted the Amsterdam Declaration 2002 which represents the official defining statement of World Humanism.


title: Secular humanism

text: All member organisations of the International Humanist and Ethical Union are required by bylaw 5.1 to accept the "Minimum Statement on Humanism":


title: Secular humanism

text: Humanism is a democratic and ethical life stance, which affirms that human beings have the right and responsibility to give meaning and shape to their own lives. It stands for the building of a more humane society through an ethic based on human and other natural values in the spirit of reason and free inquiry through human capabilities. It is not theistic, and it does not accept supernatural views of reality.


title: Secular humanism

text: To promote and unify "Humanist" identity, prominent members of the IHEU have endorsed the following statements on Humanist identity:


title: Secular humanism

text: According to the Council for Secular Humanism, within the United States, the term "secular humanism" describes a world view with the following elements and principles:


title: Secular humanism

text: "A Secular Humanist Declaration" was issued in 1980 by the Council for Secular Humanism's predecessor, CODESH. It lays out ten ideals: Free inquiry as opposed to censorship and imposition of belief; separation of church and state; the ideal of freedom from religious control and from jingoistic government control; ethics based on critical intelligence rather than that deduced from religious belief; moral education; religious skepticism; reason; a belief in science and technology as the best way of understanding the world; evolution; and education as the essential method of building humane, free, and democratic societies.


title: Secular humanism

text: A general outline of Humanism is also set out in the "Humanist Manifesto" prepared by the American Humanist Association.


title: Secular humanism

text: In the 20th and 21st centuries, members of Humanist organizations have disagreed as to whether Humanism is a religion. They categorize themselves in one of three ways. Religious (or ethical) humanism, in the tradition of the earliest humanist organizations in the UK and US, attempts to fulfil the traditional social role of religion. Contemporary use of the word "religious" did not have the same connotations as its today. Secular humanism considers all forms of religion, including religious humanism, to be superseded.