History.

In 1875, Richard Caton (1842–1926), a physician practicing in Liverpool, presented his findings about electrical phenomena of the exposed cerebral hemispheres of rabbits and monkeys in the "British Medical Journal". In 1890, Polish physiologist Adolf Beck published an investigation of spontaneous electrical activity of the brain of rabbits and dogs that included rhythmic oscillations altered by light. Beck started experiments on the electrical brain activity of animals. Beck placed electrodes directly on the surface of the brain to test for sensory stimulation. His observation of fluctuating brain activity led to the conclusion of brain waves.  In 1912, Ukrainian physiologist Vladimir Vladimirovich Pravdich-Neminsky published the first animal EEG and the evoked potential of the mammalian (dog). In 1914, Napoleon Cybulski and Jelenska-Macieszyna photographed EEG recordings of experimentally induced seizures.  German physiologist and psychiatrist Hans Berger (1873–1941) recorded the first human EEG in 1924. Expanding on work previously conducted on animals by Richard Caton and others, Berger also invented the electroencephalogram (giving the device its name), an invention described "as one of the most surprising, remarkable, and momentous developments in the history of clinical neurology". His discoveries were first confirmed by British scientists Edgar Douglas Adrian

Medical use.

EEG is one of the main diagnostic tests for epilepsy. A routine clinical EEG recording typically lasts 20–30 minutes (plus preparation time). It is a test that detects electrical activity in the brain using small, metal discs (electrodes) attached to the scalp. Routinely, EEG is used in clinical circumstances to determine changes in brain activity that might be useful in diagnosing brain disorders, especially epilepsy or another seizure disorder. An EEG might also be helpful for diagnosing or treating the following disorders:  It can also:  At times, a routine EEG is not sufficient to establish the diagnosis and/or to determine the best course of action in terms of treatment. In this case, attempts may be made to record an EEG while a seizure is occurring. This is known as an ictal recording, as opposed to an inter-ictal recording which refers to the EEG recording between seizures. To obtain an ictal recording, a prolonged EEG is typically performed accompanied by a time-synchronized video and audio recording. This can be done either as an outpatient (at home) or during a hospital admission, preferably to an Epilepsy Monitoring Unit (EMU) with nurses and other personnel trained in the care of patients with seizures. Outpatient ambulatory video EEGs typically last one to three days. An admission to an Epilepsy Monitoring Unit typically lasts several days but may last for a week or longer. While in the hospital, seizure medications are usually withdrawn to increase the odds that a seizure will occur during admission. For reasons of safety, medications are not withdrawn during an EEG outside of the hospital. Ambulatory video EEGs, therefore, have the advantage of convenience and are less

Research use.

EEG, and the related study of ERPs are used extensively in neuroscience, cognitive science, cognitive psychology, neurolinguistics and psychophysiological research, but also to study human functions such as swallowing. Many EEG techniques used in research are not standardised sufficiently for clinical use, and many ERP studies fail to report all of the necessary processing steps for data collection and reduction, limiting the reproducibility and replicability of many studies. But research on mental disabilities, such as auditory processing disorder (APD), ADD, or ADHD, is becoming more widely known and EEGs are used as research and treatment.

Advantages.

Several other methods to study brain function exist, including functional magnetic resonance imaging (fMRI), positron emission tomography (PET), magnetoencephalography (MEG), nuclear magnetic resonance spectroscopy (NMR or MRS), electrocorticography

With other neuroimaging techniques.

Simultaneous EEG recordings and fMRI scans have been obtained successfully, though recording both at the same time effectively requires that several technical difficulties be overcome, such as the presence of ballistocardiographic artifact, MRI pulse artifact and the induction of electrical currents in EEG wires that move within the strong magnetic fields of the MRI. While challenging, these have been successfully overcome in a number of studies.  MRI's produce detailed images created by generating strong

Mechanisms.

The brain's electrical charge is maintained by billions of neurons. Neurons are electrically charged (or "polarized") by membrane transport proteins that pump ions across their membranes. Neurons are constantly exchanging ions with the extracellular milieu, for example to maintain resting potential and to propagate action potentials. Ions of similar charge repel each other, and when many ions are pushed out of many neurons at the same time, they can push their neighbours, who push their neighbours, and so on, in a wave. This process is known as volume conduction. When the wave of ions reaches the electrodes on the scalp, they can push or pull electrons on the metal in the electrodes. Since metal conducts the push and pull of electrons easily, the difference in push or pull voltages between any two electrodes can be measured by a voltmeter. Recording these voltages over time gives us the EEG.  The

Method.

In conventional scalp EEG, the recording is obtained by placing electrodes on the scalp with a conductive gel or paste, usually after preparing the scalp area by light abrasion to reduce impedance due to dead skin cells. Many systems typically use electrodes, each of which is attached to an individual wire. Some systems use caps or nets into which electrodes are embedded; this is particularly common when high-density arrays of electrodes are needed.  Electrode locations and names are specified by the International 10–20 system for most clinical and research applications (except when high-density arrays are used). This system ensures that the naming of electrodes is consistent across laboratories. In most clinical applications, 19 recording electrodes (plus ground and system reference) are used. A smaller number of electrodes are typically used when recording EEG from neonates. Additional electrodes can be added to the standard set-up when a clinical or research application demands increased spatial resolution for a particular area of the brain. High-density arrays (typically via cap or net) can contain up to 256 electrodes more-or-less evenly spaced around the scalp.  Each electrode is connected to one input of a differential amplifier (one amplifier per pair of electrodes); a common system reference electrode is connected to the other input of each differential amplifier. These amplifiers amplify the voltage between the active electrode and the reference (typically 1,000–100,000 times, or 60–100 dB of voltage gain). In analog EEG, the signal is then filtered (next paragraph), and the EEG signal is output as the deflection of pens as paper passes underneath. Most EEG systems these days, however, are digital, and the amplified signal is digitized via an analog-to-digital converter, after being passed through an anti-aliasing filter. Analog-to-digital sampling typically occurs at 256–512 Hz in clinical scalp EEG; sampling rates of up to 20 kHz are used in some research applications.  During the recording, a series of activation procedures may be used. These procedures may induce normal or abnormal EEG activity that might not otherwise be seen. These procedures include hyperventilation, photic stimulation (with a strobe light), eye closure, mental activity, sleep and sleep deprivation. During (inpatient) epilepsy monitoring, a patient's typical seizure medications may be withdrawn.  The digital EEG signal is stored electronically and can be filtered for display. Typical settings for the high-pass filter and a low-pass filter are 0.5–1 Hz and 35–70 Hz respectively. The high-pass filter typically filters out slow artifact, such as electrogalvanic signals and movement artifact, whereas the low-pass filter filters out high-frequency artifacts, such as electromyographic signals. An additional notch filter is typically used to remove artifact caused by electrical power lines (60 Hz in the United States and 50 Hz in many other countries).  The EEG signals can be captured with opensource hardware such as OpenBCI and the signal can be processed by freely available EEG software such as EEGLAB or the Neurophysiological Biomarker Toolbox.  As part of an evaluation for epilepsy surgery, it may be necessary to insert electrodes near the surface of the brain, under the surface of the dura mater. This is accomplished via burr hole or craniotomy. This is referred to variously as "electrocorticography (ECoG)", "intracranial EEG (I-EEG)" or "subdural EEG (SD-EEG)". Depth electrodes may also be placed into brain structures, such as the amygdala or hippocampus, structures, which are common epileptic foci and may not be "seen" clearly by scalp EEG. The electrocorticographic signal is processed in the same manner as digital scalp EEG (above), with a couple of caveats. ECoG is typically recorded at higher sampling rates than scalp EEG because of the requirements of Nyquist theorem—the subdural signal is composed of a higher predominance of higher frequency components. Also, many of the artifacts that affect scalp EEG do not impact ECoG, and therefore display filtering is often not needed.  A typical adult human EEG signal is about 10 μV to 100 μV in amplitude when measured from the scalp.  Since an EEG voltage signal represents a difference between the voltages at two electrodes, the display of the EEG for the reading encephalographer may be set up in one of several ways. The representation of the EEG channels is referred to as a "montage."  When analog (paper) EEGs are used, the technologist switches between montages during the recording in order to highlight or better characterize certain features of the EEG. With digital EEG, all signals are typically digitized and stored in a particular (usually referential) montage; since any montage can be constructed mathematically from any other, the EEG can be viewed by the electroencephalographer in any display montage that is desired.  The EEG is read by a clinical neurophysiologist or neurologist (depending on local custom and law regarding medical specialities), optimally one who has specific training in the interpretation of EEGs for clinical purposes. This is done by visual inspection of the waveforms, called graphoelements. The use of computer signal processing of the EEG—so-called quantitative electroencephalography—is somewhat controversial when used for clinical purposes (although there are many research uses).

Normal activity.

The EEG is typically described in terms of (1) rhythmic activity and (2) transients. The rhythmic activity is divided into bands by frequency. To some degree, these frequency bands are a matter of nomenclature (i.e., any rhythmic activity between 8–12 Hz can be described as "alpha"), but these designations arose because rhythmic activity within a certain frequency range was noted to have a certain distribution over the scalp or a certain biological significance. Frequency bands are usually extracted using spectral methods (for instance Welch) as implemented for instance in freely available EEG software such as EEGLAB or the Neurophysiological Biomarker Toolbox. Computational processing of the EEG is often named quantitative electroencephalography (qEEG).  Most of the cerebral signal observed in the scalp EEG falls in the range of 1–20 Hz (activity below or above this range is likely to be artifactual, under standard clinical recording techniques). Waveforms are subdivided into bandwidths known as alpha, beta, theta, and delta to signify the majority of the EEG used in clinical practice.

Comparison of EEG bands.

The practice of using only whole numbers in the definitions comes from practical considerations in the days when only whole cycles could be counted on paper records. This leads to gaps in the definitions, as seen elsewhere on this page. The theoretical definitions have always been more carefully defined to include all frequencies.

Wave patterns.

"Ultra-slow" or "near-DC" activity is recorded using DC amplifiers in some research contexts. It is not typically recorded in a clinical context because the signal at these frequencies is susceptible to a number of artifacts.  Some features of the EEG are transient rather than rhythmic. Spikes and sharp waves may represent seizure activity or interictal activity in individuals with epilepsy or a predisposition toward epilepsy. Other transient features are normal: vertex waves and sleep spindles are seen in normal sleep.  Note that there are types of activity that are statistically uncommon, but not associated with dysfunction or disease. These are often referred to as "normal variants". The mu rhythm is an example of a normal variant.  The normal electroencephalogram (EEG) varies by age. The prenatal EEG and neonatal EEG is quite different from the adult EEG. Fetuses in the third trimester and newborns display two common brain activity patterns: "discontinuous" and "trace alternant." "Discontinuous" electrical activity refers to sharp bursts of electrical activity followed by low frequency waves. "Trace alternant" electrical activity describes sharp bursts followed by short high amplitude intervals

Artifacts.

Biological artifacts.

Electrical signals detected along the scalp by an EEG, but are of non-cerebral origin are called artifacts. EEG data is almost always contaminated by such artifacts. The amplitude of artifacts can be quite large relative to the size of amplitude of the cortical signals of interest. This is one of the reasons why it takes considerable experience to correctly interpret EEGs clinically. Some of the most common types of biological artifacts include:  The most prominent eye-induced artifacts are caused by the potential difference

Environmental artifacts.

In addition to artifacts generated by the body, many artifacts originate from outside the body. Movement by the patient, or even just settling of the electrodes, may cause "electrode pops", spikes originating from a momentary change in the impedance of a given electrode. Poor grounding of the EEG electrodes can cause significant 50 or 60 Hz artifact, depending on the local power system's frequency. A third source of possible interference can be the presence of an IV drip; such devices

Artifact correction.

Recently, independent component analysis (ICA) techniques have been used to correct or remove EEG contaminants. These techniques attempt to "unmix" the EEG signals into some number of underlying components. There are many source separation algorithms, often assuming various behaviors or natures of EEG. Regardless, the principle behind any particular method usually allow "remixing" only those components that would result in "clean" EEG by nullifying (zeroing) the weight

Abnormal activity.

Abnormal activity can broadly be separated into epileptiform and non-epileptiform activity. It can also be separated into focal or diffuse.  Focal epileptiform discharges represent fast, synchronous potentials in a large number of neurons in a somewhat discrete area of the brain. These can occur as interictal activity, between seizures, and represent an area of cortical irritability that may be predisposed to producing epileptic seizures. Interictal discharges are not wholly reliable for determining whether a patient has epilepsy nor where his/her seizure might originate. (See focal epilepsy.)  Generalized epileptiform discharges often have an anterior maximum, but these are seen synchronously throughout the entire brain. They are strongly suggestive of a generalized epilepsy.  Focal non-epileptiform abnormal activity may occur over areas of the brain where there is focal damage of the cortex or white matter. It often consists of an increase in slow frequency rhythms and/or a loss of normal higher frequency rhythms. It may also appear as focal or unilateral decrease in amplitude of the EEG signal.  Diffuse non-epileptiform abnormal activity may manifest as diffuse abnormally slow rhythms or bilateral slowing of normal rhythms, such as the PBR.  Intracortical Encephalogram electrodes and sub-dural electrodes can be used in tandem to discriminate and discretize artifact from epileptiform and other severe neurological events.  More advanced measures of abnormal EEG signals have also recently received attention as possible biomarkers for different disorders such as Alzheimer's disease.

Remote communication.

The United States Army Research Office budgeted $4 million in 2009 to researchers at the University of California, Irvine to develop EEG processing

EEG diagnostics.

The Department of Defense (DoD) and Veteran’s Affairs (VA), and U.S Army Research Laboratory (ARL), collaborated on EEG diagnostics in order to detect mild to moderate Traumatic Brain Injury (mTBI) in combat soldiers. Between 2000 and 2012 seventy-five percent of U.S. military operations brain injuries were classified mTBI. In response, the DoD pursued new technologies capable of rapid, accurate, non-invasive, and field-capable detection of mTBI to address this injury.  Combat personnel often suffer PTSD and mTBI in correlation. Both

Economics.

Inexpensive EEG devices exist for the low-cost research and consumer markets. Recently, a few companies have miniaturized

Future research.

The EEG has been used for many purposes besides the conventional uses of clinical diagnosis and conventional cognitive neuroscience. An early use was during World War II by the U.S. Army Air Corps to screen out pilots in danger of having seizures; long-term EEG recordings in epilepsy patients are still used today for seizure prediction. Neurofeedback remains an important extension, and in its most advanced form is also attempted as the basis of brain computer interfaces. The EEG is also used quite extensively in the field of neuromarketing.  The EEG is altered by drugs that affect brain functions, the chemicals that are the basis for psychopharmacology. Berger's early experiments recorded the effects of drugs on EEG. The science of pharmaco-electroencephalography has developed methods to identify substances that systematically alter brain functions for therapeutic and recreational use.  Honda is attempting to develop a system to enable an operator to control its Asimo robot using EEG, a technology it eventually hopes to incorporate into its automobiles.  EEGs have

References.

65. Keiper, A. (2006). The age of neuroelectronics. "The New Atlantis", 11, 4-41.

Electroencephalography (EEG) is an electrophysiological monitoring method to record electrical activity of the brain. It is typically noninvasive, with the electrodes placed along the scalp, although invasive electrodes are sometimes used, as in electrocorticography. EEG measures voltage fluctuations resulting from ionic current within the neurons of the brain. Clinically, EEG refers to the recording of the brain's spontaneous electrical activity over a period of time, as recorded from multiple electrodes placed on the scalp. Diagnostic applications generally focus either on event-related potentials or on the spectral content of EEG. The former investigates potential fluctuations time locked to an event, such as'stimulus onset' or 'button press'. The latter analyses the type of neural oscillations (popularly called "brain waves") that can be observed in EEG signals in the frequency domain.

脑电图、脑波图(英语:Electroencephalography, EEG)是透过医学仪器脑电图描记仪,将人体脑部自身产生的微弱生物电于头皮处收集,并放大记录而得到的曲线图。脑电图所测量的是众多锥体细胞兴奋时的突触后电位的同步总和,脑电图测量来自大脑中神经元的离子电流产生的电压波动。脑电图用于辅助诊断脑部相关疾病,但因为其易受到干扰,故临床上通常要结合其他手段来使用。


Description.

The electric immobiliser/alarm system was invented by St. George Evans and Edward Birkenbuel and patented in 1919. They developed a 3x3 grid of double-contact switches on a panel mounted inside the car so when the ignition switch was activated, current from the battery (or magneto) went to the spark plugs allowing the engine to start, or immobilizing the vehicle and sounding its horn. The system settings could be changed each time the car was driven. Modern immobiliser systems are automatic, meaning the owner does not have to remember to activate it.  Immobilisers have been mandatory in all new cars sold in Germany since 1 January 1998, in the United Kingdom since 1 October 1998, in Finland since 1998, in Australia since 2001 and in Canada since 2007. Early models used a static code in the ignition key (or key fob) which was recognised by an RFID loop around the lock barrel and checked against the vehicle's engine control unit (ECU) for a match. If the code is unrecognised, the ECU will not allow fuel to flow and ignition to take place. Later models use rolling codes or advanced cryptography to defeat copying of the code from the key or ECU.  The microcircuit inside the key is activated by a small electromagnetic field which induces current to flow inside the key body, which in turn broadcasts a unique binary code which is read by the automobile's ECU. When the ECU determines that the coded key is both current and valid, the ECU activates the fuel-injection sequence.  In some vehicles, attempts to use an unauthorised or "non-sequenced" key cause the vehicle to activate a timed no-start condition and in some highly advanced systems, even use satellite or mobile phone communication to alert a security firm that an unauthorised attempt was made to code a key.  Coincidentally, this information is often recorded in modern automobile ECUs, which may record many other variables including speed, temperature, driver weight, geographic location, throttle position and yaw angle. This information can be used during insurance investigations, warranty claims or technical troubleshooting.

Availability.

Add-on immobilisers are available for older cars or vehicles that do not come equipped with factory immobilisers. The insurance approval for a self-arming immobiliser is known as "Thatcham 2" after the Motor Insurance Repair Research Centre in Thatcham, England. Approved immobilisers must intercept at least two circuits; typically the low-voltage ignition circuit and the fuel pump circuit. Some may also intercept the low-current starter motor circuit from the key switch to the relay.  Statistics in Australia show that three out of four vehicle thefts are older cars stolen for joyriding, transport, or to commit another crime. Immobilisers are fitted to around 45% of all cars in Australia, but account for only 7% of those cars that are stolen. In many instances where a vehicle fitted with an immobiliser has been stolen, the thief had access to the original key. Only around one in four stolen vehicles are stolen by professional thieves. The majority of vehicles are stolen by opportunistic thieves relying on finding older vehicles that have ineffective security or none at all.  Honda was the first motorcycle manufacturer to include immobilisers on its products in the 1990s.  In September 2007, a Transport Canada regulation mandated the installation of engine immobilisers in all new lightweight vehicles and trucks manufactured in Canada.

Cracking.

Numerous vulnerabilities have been found in the immobilisers designed to protect modern cars from theft. Many vehicle immobilisers use the Megamos-chip, which has been proven to be crackable. The Megamos transponder is one of many different transponders found in today's immobiliser systems and also comes in many different versions. Hacking of an immobiliser in the real world would be performed on the vehicle, not on the key. It would be faster to program a new key to the vehicle than to try to clone the existing key, especially on modern vehicles.  Some immobiliser systems tend to remember the last key code for so long that they may even accept a non-transponder key even after the original key has been removed from the ignition for a few minutes.

Effectiveness.

A 2016 study in the "Economic Journal" finds that the immobiliser lowered the overall rate of car theft by about 40% between 1995 and 2008. The benefits in terms of prevented thefts are at least three times higher than the costs of installing the device.

An immobiliser or immobilizer is an electronic security device fitted to a motor vehicle that prevents the engine from running unless the correct transponder key (or other token) is present. This prevents the vehicle from being "hot wired" after entry has been achieved and thus reduces motor vehicle theft. Research shows that the uniform application of immobilisers reduced the rate of car theft by 40%.

发动机防盗锁止系统(英语:immobiliser或immobilizer)是一种内置到汽车中的电子装置,作用是防止发动机在没有正确钥匙(或其他验证措施)的情况下启动。它能防止窃贼进入汽车后的强行短接启动。


Personality, marriage and coronation.

Louis was born in Paris, the eldest son of Philip IV of France and Joan I of Navarre. He inherited the kingdom of Navarre on the death of his mother, on 4 April 1305, later being crowned 1 October 1307. On 21 September 1305, at age 15, he married Margaret of Burgundy and they had a daughter, Joan. Louis was known as "the Quarreler" as the result of the tensions prevailing throughout his reigns.  Both Louis and Margaret became involved in the Tour de Nesle affair towards the end of Philip's reign. In 1314, Margaret, Blanche and Joan—the latter two being the wives of Louis' brothers Charles and Philip, respectively—were arrested on charges of infidelity. Margaret and Blanche were both tried before the French parliament later that year and found guilty. Their alleged lovers were executed, and the women had their hair shorn and were sentenced to life imprisonment. Philip stood by his wife Joan, who was ultimately found innocent and released. Margaret would be imprisoned at Chateau Gaillard, where she died.  On the death of his father in 1314, Louis became King of France. Margaret of Burgundy died on 14 August 1315 and Louis remarried five days later, on 19 August to Clementia of Hungary, the daughter of Charles Martel of Anjou and the niece of Louis' own uncle and close advisor, Charles of Valois. Louis and Clementia were crowned at Reims in August 1315.

Domestic policy.

Louis was king of Navarre for eleven years and king of France for less than two years. His reign was dominated by continual feuding with the noble factions within the kingdom, and major reforms designed to increase royal revenues, such as the freeing of the French serfs and the readmittance of the Jews.  In 1315, Louis X published a decree proclaiming that "France signifies freedom" and that any slave setting foot on French soil should be freed. This prompted subsequent governments to circumscribe slavery in the overseas colonies. His "Ordonnances des Roi de France", V, p.1311 declared that "as soon as a slave breathes the air of France, he breathes freedom"

Regional leagues.

By the end of Philip IV's reign opposition to the fiscal reforms was growing. With Philip's death and the accession of Louis, this opposition rapidly developed in more open revolt, some authors citing Louis' relative youth as one of the reasons behind the timing of the rebellions. Leagues of regional nobles began to form around the country, demanding changes. Charles of Valois took advantage of this movement to turn against his old enemy, Philip IV's former minister and chamberlain Enguerrand de Marigny, and convinced Louis to bring corruption charges against him. When these failed, Charles then convinced Louis to bring sorcery charges against him instead, which proved more effective and led to de Marigny's execution at Vincennes in April 1315. Other former ministers were similarly prosecuted. This, combined with the halting of Philip's reforms, the issuing of numerous charters of rights and a reversion to more traditional rule, largely assuaged the regional leagues.

Readmittance of the Jews and reform of serfdom.

In practical terms, Louis X effectively abolished slavery within the Kingdom of France in 1315. Louis continued to require revenues, however, and alighted on a reform of French serfdom as a way of achieving this. Arguing that all men are born free, Louis declared in 1315 that French serfs would therefore be freed, although each serf would have to purchase his freedom. A body of commissioners was established to undertake the reform, establishing the "peculium", or value, of each serf. For serfs owned directly by the King, all of the "peculium" would be received by the Crown; for serfs owned by subjects of the King, the amount would be divided between the Crown and the owner. In the event, not all serfs were prepared to pay in this fashion and in due course Louis declared that the goods of these serfs would be seized anyway, with the proceeds going to pay for the war in Flanders.  Louis was also responsible for a key shift in policy towards the Jews. In 1306, his father, Philip IV, had expelled the Jewish minority from across France, a "shattering" event for most of these communities. Louis began to reconsider this policy, motivated by the additional revenues that might be forthcoming to the Crown if the Jews were allowed to return. Accordingly, Louis issued a charter in 1315, readmitting the Jews subject to various conditions. The Jews would only be admitted back into France for twelve years, after which the agreement might be terminated; Jews were to wear an armband at all times; Jews could only live in those areas where there had been Jewish communities previously; Jews were initially to be forbidden from usury. This was the first time that French Jews had been covered by such a charter, and Louis was careful to justify his decision with reference to the policies of his ancestor Saint Louis IX, the position of Pope Clement V and an argument that the people of France had demanded a return of the Jews. The result was a much weakened Jewish community that depended directly upon the King for their right of abode and protection.

Challenge of Flanders.

Louis X continued the effort of his predecessor to achieve a military solution to the vexing problem of Flanders. The Count of Flanders ruled an "immensely wealthy state" which enjoyed a largely autonomous existence on the margins of the French realm; French kings claimed to exercise suzerainty over Flanders, but heretofore with little success. Philip IV had attempted to assert royal overlordship, but his army, led by Robert II of Artois, had been defeated at Courtrai in 1302; despite a later French victory at the Battle of Mons-en-Pévèle the relationship remained testy and unsettled.  Louis mobilised an army along the Flemish border, but the French position rapidly become strained by the demands of maintaining a wartime footing. Louis had prohibited exports of grain and other material to Flanders in 1315. This proved challenging to enforce, and the king had to pressure officers of the Church in the borderlands, as well as Edward II of England, to support his effort to prevent Spanish merchant vessels from trading with the embargoed Flemish. An unintended result of the embargo was the rise of smuggling activities that reduced the advantage (and consequently the amount) of trading in compliance with royal restrictions in the border region. Louis was also forced to directly requisition food for his forces, resulting in a series of complaints from local lords and the Church.

Death and legacy.

Louis was a keen player of "jeu de paume", or real tennis, and became notable as the first person to construct indoor tennis courts in the modern style. Louis was unhappy with playing tennis out of doors and accordingly had indoor, enclosed courts made in Paris "around the end of the 13th century". In due course this design spread across royal palaces all over Europe. In June 1316 at Vincennes, following a particularly exhausting game, Louis drank a large quantity of cooled wine and subsequently died of either pneumonia or pleurisy, although there was also suspicion of poisoning. Because of the contemporary accounts of his death, Louis is history's first tennis player known by name. He and his second wife Clementia are interred in Saint Denis Basilica.  Louis' second wife Clementia was pregnant at the time of his death, leaving the succession in doubt. A son would have primacy over Louis' daughter, Joan. A daughter, however, would have a weaker claim to the throne, and would need to compete with Joan's own claims – although suspicions hung over Joan's parentage following the scandal in 1314. As a result, Louis' brother Philip was appointed regent for the five months remaining until the birth of his brother's child, John I, who lived only five days. Philip then succeeded in pressing his claims to the crowns of France and Navarre.  All "de jure" monarchs of Navarre from 1328 onwards were descended from Louis through his daughter, Joan, including Jeanne d'Albret, the mother of Henry IV of France, and therefore the entire royal House of Bourbon.

In fiction.

Louis is a major character in "Les Rois maudits" ("The Accursed Kings"), a series of French historical novels by Maurice Druon. He was portrayed by in the 1972 French miniseries adaptation of the series, and by Guillaume Depardieu in the 2005 adaptation.

Louis X (4 October 1289 – 5 June 1316), called the Quarrelsome, the Headstrong, or the Stubborn (), was King of France from 1314 to 1316, succeeding his father Philip IV. After the death of his mother, Joan I of Navarre, he was also King of Navarre as Louis I () from 1305 until his death in 1316.

(爱争吵的)路易十世(Louis X le Hutin,1289年-10月4日-1316年-6月5日)卡佩王朝第12位国王(1314年—1316年在位),纳瓦拉国王(1305年—1316年,称路易一世)。他是腓力四世(美男子)的长子,母为纳瓦拉女王胡安娜一世(法语称让娜)。出生于巴黎。


Hesiod.

Hesiod, both in his "Theogony" (briefly, without naming Pandora outright, line 570) and in "Works and Days", gives the earliest version of the Pandora story.

"Theogony".

The Pandora myth first appeared in lines 560–612 of Hesiod's poem in epic meter, the "Theogony" (c. 8th–7th centuries BC), without ever giving the woman a name. After humans received the stolen gift of fire from Prometheus, an angry Zeus decides to give humanity a punishing gift to compensate for the boon they had been given. He commands Hephaestus to mold from earth the first woman, a "beautiful evil" whose descendants would torment the human race. After Hephaestus does so, Athena dresses her in a silvery gown, an embroidered veil, garlands and an ornate crown of silver. This woman goes unnamed in the "Theogony", but is presumably Pandora, whose myth Hesiod revisited in "Works and Days". When she first appears before gods and mortals, "wonder seized them" as they looked upon her. But she was "sheer guile, not to be withstood by men." Hesiod elaborates (590–93):  <poem> From her is the race of women and female kind: of her is the deadly race and tribe of women who live amongst mortal men to their great trouble, no helpmates in hateful poverty, but only in wealth.</poem>  Hesiod goes on to lament that men who try to avoid the evil of women by avoiding marriage will fare no better (604–7):  <poem> He reaches deadly old age without anyone to tend his years, and though he at least has no lack of livelihood while he lives, yet, when he is dead, his kinsfolk divide his possessions amongst them.</poem>  Hesiod concedes that occasionally a man finds a good wife, but still (609) "evil contends with good."

"Works and Days".

The more famous version of the Pandora myth comes from another of Hesiod's poems, "Works and Days". In this version of the myth (lines 60–105), Hesiod expands upon her origin, and moreover widens the scope of the misery she inflicts on humanity. As before, she is created by Hephaestus, but now more gods contribute to her completion (63–82): Athena taught her needlework and weaving (63–4); Aphrodite "shed grace upon her head and cruel longing and cares that weary the limbs" (65–6); Hermes gave her "a shameful mind and deceitful nature" (67–8); Hermes also gave her the power of speech, putting in her "lies and crafty words" (77–80) ; Athena then clothed her (72); next Persuasion and the Charites adorned her with necklaces and other finery (72–4); the Horae adorned her with a garland crown (75). Finally, Hermes gives this woman a name: Pandora – "All-gifted" – "because all the Olympians gave her a gift" (81). (In Greek, "Pandora" has an active rather than a passive meaning; hence, Pandora properly means "All-giving." The implications of this mistranslation are explored in "All-giving Pandora: mythic inversion?" below.) In this retelling of her story, Pandora's deceitful feminine nature becomes the least of humanity's worries. For she brings with her a jar (which, due to textual corruption in the sixteenth century, came to be called a box) containing "burdensome toil and sickness that brings death to men" (91–2), diseases (102) and "a myriad other pains" (100). Prometheus had (fearing further reprisals) warned his brother Epimetheus not to accept any gifts from Zeus. But Epimetheus did not listen; he accepted Pandora, who promptly scattered the contents of her jar. As a result, Hesiod tells us, "the earth and sea are full of evils" (101). One item, however, did not escape the jar (96–9): <poem> Only Hope was left within her unbreakable house, she remained under the lip of the jar, and did not fly away. Before [she could], Pandora replaced the lid of the jar. This was the will of aegis-bearing Zeus the Cloudgatherer.</poem>  Hesiod does not say why hope ("elpis") remained in the jar. and closes with the moral (105): "Thus it is not possible to escape the mind of Zeus."  Hesiod also outlines how the end of man's Golden Age (an all-male society of immortals who were reverent to the gods, worked hard, and ate from abundant groves of fruit) was brought on by Prometheus. When he stole Fire from Mt. Olympus and gave it to mortal man, Zeus punished the technologically advanced society by creating a woman. Thus, Pandora was created and given the jar (mistranslated as 'box') which releases all evils upon man.  Archaic and Classic Greek literature seem to make little further mention of Pandora, but mythographers later filled in minor details or added postscripts to Hesiod's account. For example, the "Bibliotheca" and Hyginus each make explicit what might be latent in the Hesiodic text: Epimetheus married Pandora. They each add that the couple had a daughter, Pyrrha, who married Deucalion and survived the deluge with him. However, the Hesiodic "Catalogue of Women",, had made a "Pandora" one of the "daughters" of Deucalion, and the mother of Graecus by Zeus. In the 15th-century AD an attempt was made to conjoin pagan and scriptural narrative by the monk Annio da Viterbo, who claimed to have found an account by the ancient Chaldean historian Berossus in which "Pandora" was named as a daughter-in-law of Noah in the alternative Flood narrative.

"Pithos" into "box".

The mistranslation of "pithos", a large storage jar, as "box" is usually attributed to the sixteenth century humanist Erasmus of Rotterdam when he translated Hesiod's tale of Pandora into Latin. Hesiod's "pithos" refers to a large storage jar, often half-buried in the ground, used for wine, oil or grain. It can also refer to a funerary jar. Erasmus, however, translated "pithos" into the Latin word "pyxis", meaning "box". The phrase "Pandora's box" has endured ever since.

Difficulties of interpretation.

Historic interpretations of the Pandora figure are rich enough to have offered Dora and Erwin Panofsky scope for monographic treatment. M. L. West writes that the story of Pandora and her jar is from a pre-Hesiodic myth, and that this explains the confusion and problems with Hesiod's version and its inconclusiveness. He writes that in earlier myths, Pandora was married to Prometheus, and cites the ancient Hesiodic "Catalogue of Women" as preserving this older tradition, and that the jar may have at one point contained only good things for humanity. He also writes that it may have been that Epimetheus and Pandora and their roles were transposed in the pre-Hesiodic myths, a "mythic inversion". He remarks that there is a curious correlation between Pandora being made out of earth in Hesiod's story, to what is in the "Bibliotheca" that Prometheus created man from water and earth. Hesiod's myth of Pandora's jar, then, could be an amalgam of many variant early myths.  The meaning of Pandora's name, according to the myth provided in "Works and Days", is "all-gifted". However, according to others Pandora more properly means "all-giving". Certain vase paintings dated to the 5th century BC likewise indicate that the pre-Hesiodic myth of the goddess Pandora endured for centuries after the time of Hesiod. An alternative name for Pandora attested on a white-ground kylix (ca. 460 BC) is "Anesidora", which similarly means "she who sends up gifts." This vase painting clearly depicts Hephaestus and Athena putting the finishing touches on the first woman, as in the "Theogony". Written above this figure (a convention in Greek vase painting) is the name "Anesidora". More commonly, however, the epithet "anesidora" is applied to Gaea or Demeter. In view of such evidence, William E. Phipps has pointed out, "Classics scholars suggest that Hesiod reversed the meaning of the name of an earth goddess called Pandora (all-giving) or Anesidora (one-who-sends-up-gifts). Vase paintings and literary texts give evidence of Pandora as a mother earth figure who was worshipped by some Greeks. The main English commentary on "Works and Days" states that Hesiod shows no awareness [of this]."  Jane Ellen Harrison also turned to the repertory of vase-painters to shed light on aspects of myth that were left unaddressed or disguised in literature. On a fifth-century amphora in the Ashmolean Museum (her fig.71) the half-figure of Pandora emerges from the ground, her arms upraised in the epiphany gesture, to greet Epimetheus. A winged "ker" with a fillet hovers overhead: "Pandora rises from the earth; she "is" the Earth, giver of all gifts," Harrison observes. Over time this "all-giving" goddess somehow devolved into an "all-gifted" mortal woman. A.H. Smith, however, noted that in Hesiod's account Athena and the Seasons brought wreaths of grass and spring flowers to Pandora, indicating that Hesiod was conscious of Pandora's original "all-giving" function. For Harrison, therefore, Hesiod's story provides "evidence of a shift from matriarchy to patriarchy in Greek culture. As the life-bringing goddess Pandora is eclipsed, the death-bringing human Pandora arises." Thus, Harrison concludes "in the patriarchal mythology of Hesiod her great figure is strangely changed and diminished. She is no longer Earth-Born, but the creature, the handiwork of Olympian Zeus." (Harrison 1922:284). Robert Graves, quoting Harrison, asserts of the Hesiodic episode that "Pandora is not a genuine myth, but an anti-feminist fable, probably of his own invention." H.J. Rose wrote that the myth of Pandora is decidedly more illiberal than that of epic in that it makes Pandora the origin of all of Man's woes with her being the exemplification of the bad wife.  The Hesiodic myth did not, however, completely obliterate the memory of the all-giving goddess Pandora. A scholium to line 971 of Aristophanes' "The Birds" mentions a cult "to Pandora, the earth, because she bestows all things necessary for life". And in fifth-century Athens, Pandora made a prominent appearance in what, at first, appears an unexpected context, in a marble relief or bronze appliqués as a frieze along the base of the "Athena Parthenos", the culminating experience on the Acropolis. Jeffrey M. Hurwit has interpreted her presence there as an "anti-Athena." Both were motherless, and reinforced via opposite means the civic ideologies of patriarchy and the "highly gendered social and political realities of fifth-century Athens"—Athena by rising above her sex to defend it, and Pandora by embodying the need for it. Meanwhile, Pausanias (i.24.7) merely noted the subject and moved on.

Artistic representations.

Images of Pandora began to appear on Greek pottery as early as the 5th century BCE, although identification of the scene represented is sometimes ambiguous. An independent tradition that does not square with any of the Classical literary sources is in the visual repertory of Attic red-figure vase-painters, which sometimes supplements, sometimes ignores, the written testimony; in these representations the upper part of Pandora is visible rising from the earth, "a chthonic goddess like Gaia herself." Sometimes, but not always, she is labeled "Pandora". In some cases the figure of Pandora emerging from the earth is surrounded by figures carrying hammers in what has been suggested as a scene from a satyr play by Sophocles, "Pandora, or The Hammerers", of which only fragments remain. But there have also been alternative interpretations of such scenes.  In a late Pre-Raphaelite painting by John D. Batten, hammer-wielding workmen appear through a doorway, while in the foreground Hephaestus broods on the as yet unanimated figure of “Pandora”. There were also earlier English paintings of the newly created Pandora as surrounded by the heavenly gods presenting gifts, a scene also depicted on ancient Greek pottery. In one case it was part of a decorative scheme painted on the ceiling at Petworth House by Louis Laguerre in about 1720. William Etty’s "Pandora Crowned by the Seasons" of a century later is similarly presented as an apotheosis taking place among the clouds. In between these two had come James Barry’s huge "Birth of Pandora", on which he laboured for over a decade at the turn of the nineteenth century. Well before that he was working on the design, which was intended to reflect his theoretical writings on the interdependence between history painting and the way it should reflect the ideal state. An early drawing, only preserved now in the print made of it by Luigi Schiavonetti, follows the account of Hesiod and shows Pandora being adorned by the Graces and the Hours while the gods look on. Its ideological purpose, however, was to demonstrate an equal society unified by the harmonious function of those within it. But in the actual painting which followed much later, a subordinated Pandora is surrounded by gift-bearing gods and Minerva stands near her, demonstrating the feminine arts proper to her passive role. The shift is back to the culture of blame whenever she steps outside it.  In the individual representations of Pandora that were to follow, her idealisation is as a dangerous type of beauty, generally naked or semi-naked. She is only differentiated from other paintings or statues of such females by being given the attribute of a jar or, increasingly in the 19th century, a straight-sided box. As well as the many European paintings of her from this period, there are examples in sculptures by Henri-Joseph Ruxthiel (1819),John Gibson (1856), Pierre Loison (1861, see above) and Chauncy Bradley Ives (1871).

Pandora's relationship to Eve.

There is an additional reason why Pandora should appear nude, in that it was a theological commonplace going back to the early Church Fathers that the Classical myth of Pandora made her a type of Eve. Each is the first woman in the world; and each is a central character in a story of transition from an original state of plenty and ease to one of suffering and death, a transition which is brought about as a punishment for transgression of divine law.  It has been argued that it was as a result of the Hellenisation of Western Asia that the misogyny in Hesiod's account of Pandora began openly to influence both Jewish and then Christian interpretations of scripture. The doctrinal bias against women so initiated then continued into Renaissance times. Bishop Jean Olivier's long Latin poem "Pandora" drew on the Classical account as well as the Biblical to demonstrate that woman is the means of drawing men to sin. Originally appearing in 1541 and republished thereafter, it was soon followed by two separate French translations in 1542 and 1548. At the same period appeared a 5-act tragedy by the Protestant theologian Leonhard Culmann (1498-1568) titled "Ein schön weltlich Spiel von der schönen Pandora" (1544), similarly drawing on Hesiod in order to teach conventional Christian morality. The equation of the two also occurs in the 1550 allegorical painting by Jean Cousin the Elder, "Eva Prima Pandora" (Eve the first Pandora), in which a naked woman reclines in a grotto. Her right elbow rests on a skull, indicating the bringing of death, and she holds an apple branch in that hand – both attributes of Eve. Her left arm is wreathed by a snake (another reference to the temptation of Eve) and that hand rests on an unstopped jar, Pandora's attribute. Above hangs the sign from which the painting gains its name and beneath it is a closed jar, perhaps the counterpart of the other in Olympus, containing blessings. In Juan de Horozco's Spanish emblem book, "Emblemas morales" (1589), a motive is given for Pandora's action. Accompanying an illustration of her opening the lid of an urn from which demons and angels emerge is a commentary that condemns “female curiosity and the desire to learn by which the very first woman was deceived”. In the succeeding century that desire to learn was equated with the female demand to share the male prerogative of education. In Nicolas Regnier’s painting “The Allegory of Vanity” (1626), subtitled “Pandora”, it is typified by her curiosity about the contents of the urn that she has just unstopped and is compared to the other attributes of vanity surrounding her (fine clothes, jewellery, a pot of gold coins). Again, Pietro Paolini’s lively Pandora of about 1632 seems more aware of the effect that her pearls and fashionable headgear is making than of the evils escaping from the jar she holds. There is a social message carried by these paintings too, for education, no less than expensive adornment, is only available to those who can afford it. But an alternative interpretation of Pandora’s curiosity makes it merely an extension of childish innocence. This comes out in portrayals of Pandora as a young girl, as in Walter Crane’s “Little Pandora” spilling buttons while encumbered by the doll she is carrying, in Arthur Rackham’s book illustration and Frederick Stuart Church’s etching of an adolescent girl taken aback by the contents of the ornamental box she has opened. The same innocence informs Odilon Redon’s 1910/12 clothed figure carrying a box and merging into a landscape suffused with light, and even more the 1914 version of a naked Pandora surrounded by flowers, a primaeval Eve in the Garden of Eden. Such innocence, “naked and without alarm” in the words of an earlier French poet, portrays Pandora more as victim of a conflict outside her comprehension than as temptress.

Between Eve and Pygmalion.

Early dramatic treatments of the story of Pandora are works of musical theatre. "La Estatua de Prometeo" (1670) by Pedro Calderón de la Barca is made an allegory in which devotion to learning is contrasted with the active life. Prometheus moulds a clay statue of Minerva, the goddess of wisdom to whom he is devoted, and gives it life from a stolen sunbeam. This initiates a debate among the gods whether a creation outside their own work is justified; his devotion is in the end rewarded with permission to marry his statue. In this work, Pandora, the statue in question, plays only a passive role in the competition between Prometheus and his brother Epimetheus (signifying the active life), and between the gods and men. Another point to note about Calderón’s musical drama is that the theme of a statue married by her creator is more suggestive of the story of Pygmalion. The latter is also typical of Voltaire’s ultimately unproduced opera "Pandore" (1740). There too the creator of a statue animates it with stolen fire, but then the plot is complicated when Jupiter also falls in love with this new creation but is prevented by Destiny from consummating it. In revenge the god sends Destiny to tempt this new Eve into opening a box full of curses as a punishment for Earth’s revolt against Heaven.  If Pandora appears suspended between the roles of Eve and of Pygmalion’s creation in Voltaire’s work, in Charles-Pierre Colardeau’s erotic poem "Les Hommes de Prométhée" (1774) she is presented equally as a love-object and in addition as an unfallen Eve: Having been fashioned from clay and given the quality of “naïve grace combined with feeling”, she is set to wander through an enchanted landscape. There she encounters the first man, the prior creation of Prometheus, and warmly responds to his embrace. At the end the couple quit their marriage couch and survey their surroundings “As sovereigns of the world, kings of the universe”.  One other musical work with much the same theme was Aumale de Corsenville's one-act verse melodrama "Pandore", which had an overture and incidental music by Franz Ignaz Beck. There Prometheus, having already stolen fire from heaven, creates a perfect female, “artless in nature, of limpid innocence”, for which he anticipates divine vengeance. However, his patron Minerva descends to announce that the gods have gifted Pandora with other qualities and that she will become the future model and mother of humanity. The work was performed on 2 July 1789, on the very eve of the French Revolution, and was soon forgotten in the course of the events that followed.

19th century drama.

Over the course of the 19th century, the story of Pandora was interpreted in radically different ways by four dramatic authors in four countries. In two of these she was presented as the bride of Epimetheus; in the two others she was the wife of Prometheus. The earliest of these works was the lyrical dramatic fragment by Johann Wolfgang von Goethe, written between 1807 and 1808. Though it bears the title "Pandora", what exists of the play revolves round Epimetheus’ longing for the return of the wife who has abandoned him and has yet to arrive. It is in fact a philosophical transformation of Goethe's passion in old age for a teenaged girl.  Henry Wadsworth Longfellow’s "The Masque of Pandora" dates from 1876. It begins with her creation, her refusal by Prometheus and acceptance by Epimetheus. Then in the latter’s house an “oaken chest, Carven with figures and embossed with gold” attracts her curiosity. After she eventually gives in to temptation and opens it, she collapses in despair and a storm destroys the garden outside. When Epimetheus returns, she begs him to kill her but he accepts joint responsibility. The work was twice used as the basis for operas by Alfred Cellier in 1881 and by Eleanor Everest Freer in 1933. Iconographical elements from the masque also figure in Walter Crane's large watercolour of Pandora of 1885. She is pictured as sprawled over a carved wooden chest on which are embossed golden designs of the three fates who figure as a chorus in Longfellow's scene 3. Outside the palace, a high wind is bending the trees. But on the front of the chest, a medallion showing the serpent wound about the tree of knowledge recalls the old interpretation of Pandora as a type of Eve.  In England the high drama of the incident was travestied in James Robinson Planché’s "Olympic Revels or Prometheus and Pandora" (1831), the first of the Victorian burlesques. It is a costume drama peppered with comic banter and songs during which the gods betroth Pandora to a disappointed Prometheus with “only one little box” for dowry. When she opens it, Jupiter descends to curse her and Prometheus, but Hope emerges from the box and negotiates their pardon.  At the other end of the century, Gabriel Fauré’s ambitious opera Prométhée (1900) had a cast of hundreds, a huge orchestra and an outdoor amphitheatre for stage. It was based in part on the "Prometheus Bound" of Aeschylus but was rewritten so as to give the character of Pandore an equal part with his. This necessitated her falling “as if dead” on hearing the judgement against Prométhée in Act 1; a funeral procession bearing her body at the start of Act 2, after which she revives to mourn the carrying out of Prométhée's sentence; while in Act 3 she disobeys Prométhée by accepting a box, supposedly filled with blessings for mankind, and makes the tragedy complete.

Pandora in character.

The pattern during the 19th century had only repeated that of the nearly three millennia before it. The ancient myth of Pandora never settled into one accepted version, was never agreed to have a single interpretation. It was used as a vehicle to illustrate the prevailing ideologies or artistic fashions of the time and eventually became so worn a coinage that it grew confused with other, sometimes later, stories. Best known in the end for a single metaphorical attribute, the box with which she was not even endowed until the 16th century, depictions of Pandora have been further confused with other holders of receptacles – with one of the trials of Psyche, with Sophonisba about to drink poison or Artemisia with the ashes of her husband. Nevertheless, her very polyvalence has been in the end the guarantor of her cultural survival.

In Greek mythology, Pandora (Greek:, derived from, "pān", i.e. "all" and, "dōron", i.e. "gift", thus "the all-endowed", "all-gifted" or "all-giving") was the first human woman created by Hephaestus on the instructions of Zeus. As Hesiod related it, each god cooperated by giving her unique gifts. Her other name—inscribed against her figure on a white-ground "kylix" in the British Museum—is Anesidora (), "she who sends up gifts" ("up" implying "from below" within the earth).

潘朵拉(Pandora,),希腊神话中火神赫菲斯托斯用粘土做成的地上第一个女人,送给人类作为对普罗米修斯盗火的惩罚。众神赠予使她拥有更诱人的魅力的礼物,例如:赫菲斯托斯给她做了华丽的金长袍;爱神阿芙萝黛缇赋予她妩媚与诱惑男人的力量;神使赫尔墨斯教会了她言语的技能。


Description.

For a type II error probability of, the corresponding statistical power is 1 −. For example, if experiment E has a statistical power of 0.7, and experiment F has a statistical power of 0.95, then there is a stronger probability that experiment E had a type II error than experiment F. This reduces experiment E's sensitivity to detect significant effects. However, experiment E is consequently more reliable than experiment F due to its lower probability of a type I error. It can be equivalently thought of as the probability of accepting the alternative hypothesis (formula_2) when it is true — that is, the ability of a test to detect a specific effect, if that specific effect actually exists. Thus,  If formula_2 is not an equality but rather simply the negation of formula_1 (so for example with formula_7 for some unobserved population parameter formula_8 we have simply formula_9) then power cannot be calculated unless probabilities are known for all possible values of the parameter that violate the null hypothesis. Thus one generally refers to a test's power "against a specific alternative hypothesis".  As the power increases, there is a decreasing probability of a type II error, also called the "false negative rate" () since the power is equal to 1 −. A similar concept is the type I error probability, also referred to as the "false positive rate" or the level of a test under the null hypothesis.  Power analysis can be used to calculate the minimum sample size required so that one can be reasonably likely to detect an effect of a given size. For example: "How many times do I need to toss a coin to conclude it is rigged by a certain amount?" Power analysis can also be used to calculate the minimum effect size that is likely to be detected in a study using a given sample size. In addition, the concept of power is used to make comparisons between different statistical testing procedures: for example, between a parametric test and a nonparametric test of the same hypothesis.  In the context of binary classification, the power of a test is called its "statistical sensitivity", its "true positive rate", or its "probability of detection".

Background.

Statistical tests use data from samples to assess, or make inferences about, a statistical population. In the concrete setting of a two-sample comparison, the goal is to assess whether the mean values of some attribute obtained for individuals in two sub-populations differ. For example, to test the null hypothesis that the mean scores of men and women on a test do not differ, samples of men and women are drawn, the test is administered to them, and the mean score of one group is compared to that of the other group using a statistical test such as the two-sample "z"-test. The power of the test is the probability that the test will find a statistically significant difference between men and women, as a function of the size of the true difference between those two populations.

Factors influencing power.

Statistical power may depend on a number of factors. Some factors may be particular to a specific testing situation, but at a minimum, power nearly always depends on the following three factors:  A significance criterion is a statement of how unlikely a positive result must be, if the null hypothesis of no effect is true, for the null hypothesis to be rejected. The most commonly used criteria are probabilities of 0.05 (5%, 1 in 20), 0.01 (1%, 1 in 100), and 0.001 (0.1%, 1 in 1000). If the criterion is 0.05, the probability of the data implying an effect at least as large as the observed effect when the null hypothesis is true must be less than 0.05, for the null hypothesis of no effect to be rejected. One easy way to increase the power of a test is to carry out a less conservative test by using a larger significance criterion, for example 0.10 instead of 0.05. This increases the chance of rejecting the null hypothesis (i.e. obtaining a statistically significant result) when the null hypothesis is false; that is, it reduces the risk of a type II error (false negative regarding whether an effect exists). But it also increases the risk of obtaining a statistically significant result (i.e. rejecting the null hypothesis) when the null hypothesis is not false; that is, it increases the risk of a type I error (false positive).  The magnitude of the effect of interest in the population can be quantified in terms of an effect size, where there is greater power to detect larger effects. An effect size can be a direct value of the quantity of interest, or it can be a standardized measure that also accounts for the variability in the population. For example, in an analysis comparing outcomes in a treated and control population, the difference of outcome means formula_10 would be a direct estimate of the effect size, whereas formula_11 would be an estimated standardized effect size, where formula_12 is the common standard deviation of the outcomes in the treated and control groups. If constructed appropriately, a standardized effect size, along with the sample size, will completely determine the power. An unstandardized (direct) effect size is rarely sufficient to determine the power, as it does not contain information about the variability in the measurements.  The sample size determines the amount of sampling error inherent in a test result. Other things being equal, effects are harder to detect in smaller samples. Increasing sample size is often the easiest way to boost the statistical power of a test. How increased sample size translates to higher power is a measure of the efficiency of the test — for example, the sample size required for a given power.  The precision with which the data are measured also influences statistical power. Consequently, power can often be improved by reducing the measurement error in the data. A related concept is to improve the "reliability" of the measure being assessed (as in psychometric reliability).  The design of an experiment or observational study often influences the power. For example, in a two-sample testing situation with a given total sample size, it is optimal to have equal numbers of observations from the two populations being compared (as long as the variances in the two populations are the same). In regression analysis and analysis of variance, there are extensive theories and practical strategies for improving the power based on optimally setting the values of the independent variables in the model.

Interpretation.

Although there are no formal standards for power (sometimes referred to as ), most researchers assess the power of their tests using = 0.80 as a standard for adequacy. This convention implies a four-to-one trade off between -risk and -risk. ( is the probability of a type II error, and α is the probability of a type I error; 0.2 and 0.05 are conventional values for and ). However, there will be times when this 4-to-1 weighting is inappropriate. In medicine, for example, tests are often designed in such a way that no false negatives (type II errors) will be produced. But this inevitably raises the risk of obtaining a false positive (a type I error). The rationale is that it is better to tell a healthy patient "we may have found something—let's test further," than to tell a diseased patient "all is well."  Power analysis is appropriate when the concern is with the correct rejection of a false null hypothesis. In many contexts, the issue is less about determining if there is or is not a difference but rather with getting a more refined estimate of the population effect size. For example, if we were expecting a population correlation between intelligence and job performance of around 0.50, a sample size of 20 will give us approximately 80% power ( = 0.05, two-tail) to reject the null hypothesis of zero correlation. However, in doing this study we are probably more interested in knowing whether the correlation is 0.30 or 0.60 or 0.50. In this context we would need a much larger sample size in order to reduce the confidence interval of our estimate to a range that is acceptable for our purposes. Techniques similar to those employed in a traditional power analysis can be used to determine the sample size required for the width of a confidence interval to be less than a given value.  Many statistical analyses involve the estimation of several unknown quantities. In simple cases, all but one of these quantities are nuisance parameters. In this setting, the only relevant power pertains to the single quantity that will undergo formal statistical inference. In some settings, particularly if the goals are more "exploratory", there may be a number of quantities of interest in the analysis. For example, in a multiple regression analysis we may include several covariates of potential interest. In situations such as this where several hypotheses are under consideration, it is common that the powers associated with the different hypotheses differ. For instance, in multiple regression analysis, the power for detecting an effect of a given size is related to the variance of the covariate. Since different covariates will have different variances, their powers will differ as well.  Any statistical analysis involving multiple hypotheses is subject to inflation of the type I error rate if appropriate measures are not taken. Such measures typically involve applying a higher threshold of stringency to reject a hypothesis in order to compensate for the multiple comparisons being made ("e.g." as in the Bonferroni method). In this situation, the power analysis should reflect the multiple testing approach to be used. Thus, for example, a given study may be well powered to detect a certain effect size when only one test is to be made, but the same effect size may have much lower power if several tests are to be performed.  It is also important to consider the statistical power of a hypothesis test when interpreting its results. A test's power is the probability of correctly rejecting the null hypothesis when it is false; a test's power is influenced by the choice of significance level for the test, the size of the effect being measured, and the amount of data available. A hypothesis test may fail to reject the null, for example, if a true difference exists between two populations being compared by a t-test but the effect is small and the sample size is too small to distinguish the effect from random chance. Many clinical trials, for instance, have low statistical power to detect differences in adverse effects of treatments, since such effects may be rare and the number of affected patients small.

"A priori" vs. "post hoc" analysis.

Power analysis can either be done before ("a priori" or prospective power analysis) or after ("post hoc" or retrospective power analysis) data are collected. "A priori" power analysis is conducted prior to the research study, and is typically used in estimating sufficient sample sizes to achieve adequate power. "Post-hoc" analysis of "observed power" is conducted after a study has been completed, and uses the obtained sample size and effect size to determine what the power was in the study, assuming the effect size in the sample is equal to the effect size in the population. Whereas the utility of prospective power analysis in experimental design is universally accepted, post hoc power analysis is fundamentally flawed. Falling for the temptation to use the statistical analysis of the collected data to estimate the power will result in uninformative and misleading values. In particular, it has been shown that "post-hoc" "observed power" is a one-to-one function of the "p"-value attained. This has been extended to show that all "post-hoc" power analyses suffer from what is called the "power approach paradox" (PAP), in which a study with a null result is thought to show "more" evidence that the null hypothesis is actually true when the "p"-value is smaller, since the apparent power to detect an actual effect would be higher. In fact, a smaller "p"-value is properly understood to make the null hypothesis "relatively" less likely to be true.

Application.

Funding agencies, ethics boards and research review panels frequently request that a researcher perform a power analysis, for example to determine the minimum number of animal test subjects needed for an experiment to be informative. In frequentist statistics, an underpowered study is unlikely to allow one to choose between hypotheses at the desired significance level. In Bayesian statistics, hypothesis testing of the type used in classical power analysis is not done. In the Bayesian framework, one updates his or her prior beliefs using the data obtained in a given study. In principle, a study that would be deemed underpowered from the perspective of hypothesis testing could still be used in such an updating process. However, power remains a useful measure of how much a given experiment size can be expected to refine one's beliefs. A study with low power is unlikely to lead to a large change in beliefs.

Example.

The following is an example that shows how to compute power for a randomized experiment: Suppose the goal of an experiment is to study the effect of a treatment on some quantity, and compare research subjects by measuring the quantity before and after the treatment, analyzing the data using a paired t-test. Let formula_13 and formula_14 denote the pre-treatment and post-treatment measures on subject formula_15, respectively. The possible effect of the treatment should be visible in the differences formula_16 which are assumed to be independently distributed, all with the same expected mean value and variance.  The effect of the treatment can be analyzed using a one-sided t-test. The null hypothesis of no effect will be that the mean difference will be zero, i.e. formula_17 In this case, the alternative hypothesis states a positive effect, corresponding to formula_18 The test statistic is:  where  Now suppose that the alternative hypothesis is true and formula_26. Then, the power is  For large, formula_28 approximately follows a standard normal distribution when the alternative hypothesis is true, the approximate power can be calculated as  According to this formula, the power increases with the values of the parameter formula_30 For a specific value of formula_31 a higher power may be obtained by increasing the sample size.  It is not possible to guarantee a sufficient large power for all values of formula_32 as formula_31 may be very close to 0. The minimum (infimum) value of the power is equal to the confidence level of the test, formula_34 in this example 0.05. However, it is of no importance to distinguish between formula_35 and small positive values. If it is desirable to have enough power, say at least 0.90, to detect values of formula_36 the required sample size can be calculated approximately:  from which it follows that  Hence, using the quantile function  where formula_40 is a standard normal quantile; refer to the Probit article for an explanation of the relationship between formula_41 and z-values.

Extension.

Bayesian power.

In the frequentist setting, parameters are assumed to have a specific value which is unlikely to be true. This issue can be addressed by assuming the parameter has a distribution. The resulting power is sometimes referred to as Bayesian power which is commonly used in clinical trial design.

Predictive probability of success.

Both frequentist power and Bayesian power use statistical significance as the success criterion. However, statistical significance is often not enough to define success. To address this issue, the power concept can be extended to the concept of predictive probability of success (PPOS). The success criterion for PPOS is not restricted to statistical significance and is commonly used in clinical trial designs.

Software for power and sample size calculations.

Numerous free and/or open source programs are available for performing power and sample size calculations. These include

The power of a binary hypothesis test is the probability that the test rejects the null hypothesis (formula_1) when a specific alternative hypothesis (formula_2) is true. The statistical power ranges from 0 to 1, and as statistical power increases, the probability of making a type II error (wrongly failing to reject the null hypothesis) decreases.

统计功效(英语:statistical power,又译统计考验力或统计检定力)在假设检验中是指当备择假设(H)为真时正确地拒绝零假设(H)的概率,即


Biography.

Camillo Golgi was born in July 1843 in the village of Corteno, in the province of Brescia (Lombardy), Italy. The village is now named Corteno Golgi in his honour. His father Alessandro Golgi was a physician and district medical officer, originally from Pavia. In 1860, he entered the University of Pavia to study medicine, and earned his medical degree in 1865. He did an internship at the San Matteo Hospital (now IRCCS Policlinico San Matteo Foundation). During his internship he briefly worked as a civil physician in the Italian Army, and as assistant surgeon at the Novara Hospital (now Azienda Ospedaliero Universitaria Maggiore della Carità di Novara). At the same time he was also involved in the medical team for investigating cholera epidemic in villages around Pavia.  In 1867, he resumed his academic study under the supervision of Cesare Lombroso. Lombroso was a renowned scientist in medical psychology such as genius, madness and criminality. Inspired by Lombroso, Golgi wrote a thesis on the etiology of mental disorders, from which he obtained his M.D. in 1868. He became more interested in experimental medicine, and started attending the Institute of General Pathology headed by Giulio Bizzozero. Three years his junior, Bizzozero was an eloquent teacher and experimenter, who specialised in histology of the nervous system and the properties of bone marrow. The most important research publications of Golgi were directly or indirectly influenced by Bizzozero. The two became so close that they lived in the same building; and Golgi later married Bizzozero's niece, Lina Aletti. By 1872, Golgi was an established clinician and histopathologist. He, however, had no opportunity as a tenured professor in Pavia to pursue teaching and research in neurology.  Financial pressure prompted him to join the Hospital of the Chronically Ill (Pio Luogo degli Incurabili) in Abbiategrasso, near Milan, as Chief Medical Officer in 1872. To continue research, he set up a simple laboratory on his own in a refurbished hospital kitchen, and it was there that he started making his most notable discoveries. His major achievement was the development of staining technique for nerve tissue called the black reaction (later the Golgi's method). He published his major works between 1875 and 1885 in the journal "Rivista sperimentale di Freniatria e di medicina legale". In 1875, he joined the faculty of histology at the University of Pavia. In 1879, he was appointed Chair of Anatomy at the University of Siena. But the next year, he returned to the University of Pavia as full Professor of histology. From 1879 he also became Professor of General Pathology as well as Honorary Chief ("Primario ad honorarem") at the San Matteo Hospital. He served as Rector of the University of Pavia twice, first between 1893 and 1896, and second between 1901 and 1909. During the First World War (1914-1917), he directed the military hospital Collegio Borrmeo at Pavia. He retired in 1918 and continued to research in his private laboratory till 1923. He died on 21 January 1926.

Personal life.

Golgi and his wife Lina Aletti had no children, and they adopted Golgi's niece Carolina.  Golgi was irreligious in his later life and became an agnostic atheist. One of his former students attempted an unsuccessful deathbed conversion on him.

Contributions.

Black reaction or Golgi's staining.

Central nervous system was difficult to study during Golgi's time because the cells were hard to identify. The available tissue staining techniques were useless for studying nervous tissue. While working as chief medical officer at the Hospital of the Chronically Ill, he experimented with metal impregnation of nervous tissue, using mainly silver (silver staining). In early 1873, he discovered a method of staining nervous tissue that would stain a limited number of cells at random in their entirety. He first treated the tissue with potassium dichromate to harden it, and then with silver nitrate. Under the microscope, the outline of the neuron became distinct from the surrounding tissue and cells. The silver chromate precipitate, as a reaction product, selectively stains only some cellular components randomly, sparing other cell parts. The silver chromate particles create a stark black deposit on the soma (nerve cell body) as well as on the axon and all dendrites, providing an exceedingly clear and well-contrasted picture of neuron against a yellow background. This makes it easier to trace the structure of the nerve cells in the brain for the first time. Since cells are selective stained in black, he called the process "la reazione nera" ("the black reaction"), but today it is called Golgi's method or the Golgi stain. On 16 February 1873, he wrote to his friend Niccolò Manfredi:  His discovery was published in the "Gazzeta Medica Italiani" on 2 August 1873.

Nervous system.

In 1871, a German anatomist Joseph von Gerlach postulated that the brain is a complex "protoplasmic network", in the form of a continuous network called the reticulum. Using his black reaction, Golgi could trace various regions of the cerebro-spinal axis, clearly distinguishing the different nervous projections, namely axon from the dendrites. He drew up a new classification of cells on the basis of the structure of their nervous prolongation. He described an extremely dense and intricate network, composed of a web of intertwined branches of axons coming from different cell layers ("diffuse nervous network"). This network structure, which emerges from the axons, is essentially different from that hypothesized by Gerlach. It was the main organ of the central nervous system according to Golgi. Thus, Golgi presented the reticular theory which states that the brain is a single network of nerve fibres, and not of discrete cells. Although Golgi's earlier works between 1873 and 1885 clearly depicted the axonal connections of cerebellar cortex and olfactory bulb as independent of one another, his later works including the Nobel Lecture showed the entire granular layer of the cerebellar cortex occupied by a network of branching and anastomosing nerve processes. This was due to his strong conviction in the reticular theory. Golgi's theory was challenged by Ramón y Cajal, who used the same technique developed by Golgi. According to Ramón y Cajal's neurone theory, the nervous system is but a collection of individual cells, the neurones, which are interconnected to form a network.  In addition to this, Golgi was the first to give clear descriptions of the structure of the cerebellum, hippocampus, spinal cord, olfactory lobe, as well as striatal and cortical lesions in a case of chorea. In 1878, he also discovered a receptor organ that senses changes in muscle tension, and is now known as Golgi tendon organ or Golgi receptor; and Golgi-Mazzoni corpuscles (pressure transductors). He further developed a stain specific for myelin (a specialised portion of axon) using potassium dichromate and mercuric chloride. Using this he discovered the myelin annular apparatus, often called the horny funnel of Golgi-Rezzonico.

Kidney.

Golgi studied kidney function during 1882 to 1889. In 1882, he published his observations on the mechanism of renal hypertrophy, which he understood to be due to renal cell proliferation. In 1884, he described tubular cell mitoses in the kidney of a person suffering from tubulointerstitial nephritis, and he noted that the process was an essential part of repairing the kidney tissue. He was the first to dissect out intact nephrons, and show that the distal tubulus (loop of Henle) of the nephron returns to its originating glomerulus, a finding that he published in 1889 ("Annotazioni intorno all'Istologia dei reni dell'uomo e di altri mammifieri e sull'istogenesi dei canalicoli oriniferi". "Rendiconti R. Acad. Lincei" 5: 545–557, 1889).

Malaria.

A French Army physician Charles Louis Alphonse Laveran discovered that malaria was caused by microscopic parasite (now called "Plasmodium falciparum") in 1880. But scientists were sceptical until Golgi intervened. It was Golgi who helped him prove that malarial parasite was a microscopic protozoan. From 1885, Golgi studied the malarial parasite and its transmission. He established two types of malaria, tertian and quartan fevers caused by "Plasmodium vivax" and "Plasmodium malariae" respectively. In 1886, he discovered that malarial fever (paroxysm) was produced by the asexual stage in the human blood (called erythocytic cycle, or Golgi cycle). In 1889-1890, Golgi and Ettore Marchiafava described the differences between benign tertian malaria and malignant tertian malaria (the latter caused by "P. falciparum"). By 1898, along with Giovanni Battista Grassi, Amico Bignami, Giuseppe Bastianelli, Angelo Celli and Marchiafava, he confirmed that malaria was transmitted by "Anopheline" mosquito.

Cell organelle.

An organelle in eukaryotice cells now known as Golgi apparatus or Golgi complex, or sometimes simply as Golgi, was discovered by Camillo Golgi. Golgi modified his black reaction using osmium dichromate solution with which he stained the nerve cells (Purkinje cells) of the cerebellum of an owl. He noticed thread-like networks inside the cells and named them "apparato reticolare interno" (internal reticular apparatus). Recognising them to be unique cellular components, he presented his discovery before the Medical-Surgical Society of Pavia in April 1898. After the same was confirmed by his assistant Emilio Veratti, he published it in the "Bollettino della Società medico-chirurgica di Pavia". However, most scientists disputed his discovery as nothing but a staining artefact. Their microscopes were not powerful enough to identify the organelles. By the 1930s, Golgi's description was largely rejected. It was only firmly established after 50 years of its discovery, when electron microscopes were developed.

Awards and legacy.

Golgi, together with Santiago Ramón y Cajal, received the Nobel Prize in Physiology or Medicine in 1906 for his studies of the structure of the nervous system. In 1900 he was named senator by King Umberto I. In 1913 he became foreign member of the Royal Netherlands Academy of Arts and Sciences. He received honorary doctorate from the University of Cambridge, University of Geneva, Kristiania University College, National and Kapodistrian University of Athens, and Paris-Sorbonne University. In 1994, the European Community commemorated him with postage stamps.

Monuments in Pavia.

In Pavia several landmarks stand as Golgi's memory.

Camillo Golgi (; 7 July 1843 – 21 January 1926) was an Italian biologist and pathologist known for his works on the central nervous system. He studied medicine at the University of Pavia (where he later spent most of his professional career) between 1860 and 1868 under the tutelage of Cesare Lombroso. Inspired by pathologist Giulio Bizzozero, he pursued research in the nervous system. His discovery of a staining technique called black reaction (sometimes called Golgi's method or Golgi's staining in his honour) in 1873 was a major breakthrough in neuroscience. Several structures and phenomena in anatomy and physiology are named for him, including the Golgi apparatus, the Golgi tendon organ and the Golgi tendon reflex.

卡米洛·高尔基(,1843年-7月7日-1926年-1月21日),是一位意大利医师与科学家,高尔基体的发现者,出生于布雷西亚。1906年因为神经系统的研究,而与西班牙的桑地牙哥·拉蒙卡哈共同获得诺贝尔生理学或医学奖。于1898年发现高尔基体,主要功能为处理细胞膜、溶酶体或内体与细胞生产的蛋白质,将它们分到不同的小泡,是细胞的中心传送系统。