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Einthoven
Willem Einthoven (21 May 1860 – 29 September 1927) was a Dutch doctor and physiologist. He invented the first practical electrocardiograph (ECG or EKG) in 1895 and received the Nobel Prize in Physiology or Medicine in 1924 for it ("for the discovery of the mechanism of the electrocardiogram"). original URL now redirects to https://ethw.org/Willem_Einthoven Background Willem Einthoven was born in Semarang on Java in the Dutch East Indies (now Indonesia), the son of Louise Marie Mathilde Caroline de Vogel and Jacob Einthoven. His father, a doctor, died when Willem was a child. His mother returned to the Netherlands with her children in 1870 and settled in Utrecht. His father was of Jewish and Dutch descent, and his mother's ancestry was Dutch and Swiss. In 1885, Einthoven received a medical degree from the University of Utrecht. He became a professor at the University of Leiden in 1886. He married his first cousin Frédérique Jeanne Louise de Vogel (7 September 1861 31 Januar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
String Galvanometer
A string galvanometer is a sensitive fast-responding measuring instrument that uses a single fine filament of wire suspended in a strong magnetic field to measure small currents. In use, a strong light source is used to illuminate the fine filament, and the optical system magnifies the movement of the filament allowing it to be observed or recorded by photography. The principle of the string galvanometer remained in use for electrocardiograms until the advent of electronic vacuum-tube amplifiers in the 1920s. History Submarine cable telegraph systems of the late 19th century used a galvanometer to detect pulses of electric current, which could be observed and transcribed into a message. The speed at which pulses could be detected by the galvanometer was limited by its mechanical inertia, and by the inductance of the multi-turn coil used in the instrument. Clément Adair, a French engineer, replaced the coil with a much faster wire or "string" producing the first string galvanome ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electrocardiography
Electrocardiography is the process of producing an electrocardiogram (ECG or EKG), a recording of the heart's electrical activity. It is an electrogram of the heart which is a graph of voltage versus time of the electrical activity of the heart using electrodes placed on the skin. These electrodes detect the small electrical changes that are a consequence of cardiac muscle depolarization followed by repolarization during each cardiac cycle (heartbeat). Changes in the normal ECG pattern occur in numerous cardiac abnormalities, including cardiac rhythm disturbances (such as atrial fibrillation and ventricular tachycardia), inadequate coronary artery blood flow (such as myocardial ischemia and myocardial infarction), and electrolyte disturbances (such as hypokalemia and hyperkalemia). Traditionally, "ECG" usually means a 12-lead ECG taken while lying down as discussed below. However, other devices can record the electrical activity of the heart such as a Holter monitor but also s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Einthoven's Triangle
Einthoven's triangle is an imaginary formation of three limb leads in a triangle used in electrocardiography, formed by the two shoulders and the pubis. The shape forms an inverted equilateral triangle with the heart at the center. It is named after Willem Einthoven, who theorized its existence. Einthoven used these measuring points, by immersing the hands and foot in pails of salt water, as the contacts for his string galvanometer, the first practical ECG machine. Lead placements * Lead I — This axis goes from shoulder to shoulder, with the negative electrode placed on the right shoulder and the positive electrode placed on the left shoulder. This results in a 0 degree angle of orientation. : I = LA - RA * Lead II — This axis goes from the right arm to the left leg, with the negative electrode on the shoulder and the positive one on the leg. This results in a +60 degree angle of orientation. : II = LL - RA * Lead III — This axis goes from the left shoulder (negative el ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Willem Thomas De Vogel
Willem Thomas de Vogel (26 March 1863 10 March 1955) was a colonial Dutch doctor and official who established the Department of Public Health in the Dutch East Indies (now Indonesia). Life Early life Willem Thomas de Vogel was born on 26 March 1863 in Toeban (now Tuban), Lasem (now Rembang), on Java in the Dutch East Indies. His father Henri Adrien Frédéric de Vogel (24 January 1825 17 August 1897) was Dutch but his mother Augusta Mary Stavers de Vogel (16 December 1840 4 January 1915) English; his sisters were Frances Maria Wilhelmina de Vogel Monod de Froideville (26 December 1859 4 March 1904), Frédérique Jeanne Louise de Vogel Einthoven (7 September 186131 January 1937), Augusta Henriette de Vogel (20 January 1866 8 December 1959), Rosetta Catherina Albertine de Vogel (16 January 1868 19 January 1949), and Catherine Elisabeth de Vogel Julius Roelants (4 July 1871 28 June 1959). He received his primary education from private tutors but went to Arnhem in the Netherlands for ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Willem Einthoven ECG
Willem () is a Dutch and West FrisianRienk de Haan, ''Fryske Foarnammen'', Leeuwarden, 2002 (Friese Pers Boekerij), , p. 158. masculine given name. The name is Germanic, and can be seen as the Dutch equivalent of the name William in English, Guillaume in French, Guilherme in Portuguese, Guillermo in Spanish and Wilhelm in German. Nicknames that are derived from Willem are Jelle, Pim, Willie, Willy and Wim. Given name *Willem Cody (2007-Present), Active Serbian terrorist, Leader of the Serbian World Republic, Intolerably based * Willem I (1772–1843), King of the Netherlands * Willem II (1792–1849), King of the Netherlands * Willem III (1817–1890), King of the Netherlands * Willem of the Netherlands (1840–1879), Dutch prince *Willem-Alexander (b. 1967), King of the Netherlands *Willem Aantjes (b. 1923), Dutch politician *Willem Adelaar (b. 1948), Dutch linguist *Willem Andriessen (1887–1964), Dutch pianist and composer *Willem Arondeus (1894–1943), Dutch artist and a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Semarang
Semarang ( jv, ꦏꦸꦛꦯꦼꦩꦫꦁ , Pegon: سماراڠ) is the capital and largest city of Central Java province in Indonesia. It was a major port during the Dutch colonial era, and is still an important regional center and port today. The city has been named as the cleanest tourist destination in Southeast Asia by the ASEAN Clean Tourist City Standard (ACTCS) for 2020–2022. It has an area of and is located at . The population of the city was 1,555,984 at the 2010 censusBiro Pusat Statistik, Jakarta, 2011. and 1,653,524 at the 2020 census,Badan Pusat Statistik, Jakarta, 2021. making it Indonesia's ninth most populous city after Jakarta, Surabaya, Bekasi, Bandung, Medan, Depok, Tangerang and Palembang. The built-up urban area had 3,183,516 inhabitants at the 2010 census spread over two cities and 26 districts. The Semarang metropolitan area (a.k.a. ''Kedungsepur'') has a population of over 6 million in 2020 (''see Greater Semarang section''). The population of the cit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Leiden
Leiden (; in English and archaic Dutch also Leyden) is a city and municipality in the province of South Holland, Netherlands. The municipality of Leiden has a population of 119,713, but the city forms one densely connected agglomeration with its suburbs Oegstgeest, Leiderdorp, Voorschoten and Zoeterwoude with 206,647 inhabitants. The Netherlands Central Bureau of Statistics (CBS) further includes Katwijk in the agglomeration which makes the total population of the Leiden urban agglomeration 270,879, and in the larger Leiden urban area also Teylingen, Noordwijk, and Noordwijkerhout are included with in total 348,868 inhabitants. Leiden is located on the Oude Rijn, at a distance of some from The Hague to its south and some from Amsterdam to its north. The recreational area of the Kaag Lakes (Kagerplassen) lies just to the northeast of Leiden. A university city since 1575, Leiden has been one of Europe's most prominent scientific centres for more than four centuries. Leide ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
University Of Leiden
Leiden University (abbreviated as ''LEI''; nl, Universiteit Leiden) is a public research university in Leiden, Netherlands. The university was founded as a Protestant university in 1575 by William, Prince of Orange, as a reward to the city of Leiden for its defence against Spanish attacks during the Eighty Years' War. As the oldest institution of higher education in the Netherlands, it enjoys a reputation across Europe and the world. Known for its historic foundations and emphasis on the social sciences, the university came into particular prominence during the Dutch Golden Age, when scholars from around Europe were attracted to the Dutch Republic due to its climate of intellectual tolerance and Leiden's international reputation. During this time, Leiden became the home to individuals such as René Descartes, Rembrandt, Christiaan Huygens, Hugo Grotius, Baruch Spinoza and Baron d'Holbach. The university has seven academic faculties and over fifty subject departments while hou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Heart Disease
Cardiovascular disease (CVD) is a class of diseases that involve the heart or blood vessels. CVD includes coronary artery diseases (CAD) such as angina and myocardial infarction (commonly known as a heart attack). Other CVDs include stroke, heart failure, hypertensive heart disease, rheumatic heart disease, cardiomyopathy, abnormal heart rhythms, congenital heart disease, valvular heart disease, carditis, aortic aneurysms, peripheral artery disease, thromboembolic disease, and venous thrombosis. The underlying mechanisms vary depending on the disease. It is estimated that dietary risk factors are associated with 53% of CVD deaths. Coronary artery disease, stroke, and peripheral artery disease involve atherosclerosis. This may be caused by high blood pressure, smoking, diabetes mellitus, lack of exercise, obesity, high blood cholesterol, poor diet, excessive alcohol consumption, and poor sleep, among other things. High blood pressure is estimated to account for approximatel ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Equilateral Triangle
In geometry, an equilateral triangle is a triangle in which all three sides have the same length. In the familiar Euclidean geometry, an equilateral triangle is also equiangular; that is, all three internal angles are also congruent to each other and are each 60°. It is also a regular polygon, so it is also referred to as a regular triangle. Principal properties Denoting the common length of the sides of the equilateral triangle as a, we can determine using the Pythagorean theorem that: *The area is A=\frac a^2, *The perimeter is p=3a\,\! *The radius of the circumscribed circle is R = \frac *The radius of the inscribed circle is r=\frac a or r=\frac *The geometric center of the triangle is the center of the circumscribed and inscribed circles *The altitude (height) from any side is h=\frac a Denoting the radius of the circumscribed circle as ''R'', we can determine using trigonometry that: *The area of the triangle is \mathrm=\fracR^2 Many of these quantities have simple r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sound
In physics, sound is a vibration that propagates as an acoustic wave, through a transmission medium such as a gas, liquid or solid. In human physiology and psychology, sound is the ''reception'' of such waves and their ''perception'' by the brain. Only acoustic waves that have frequencies lying between about 20 Hz and 20 kHz, the audio frequency range, elicit an auditory percept in humans. In air at atmospheric pressure, these represent sound waves with wavelengths of to . Sound waves above 20 kHz are known as ultrasound and are not audible to humans. Sound waves below 20 Hz are known as infrasound. Different animal species have varying hearing ranges. Acoustics Acoustics is the interdisciplinary science that deals with the study of mechanical waves in gasses, liquids, and solids including vibration, sound, ultrasound, and infrasound. A scientist who works in the field of acoustics is an ''acoustician'', while someone working in the field of acoustica ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Google Doodle
A Google Doodle is a special, temporary alteration of the logo on Google's homepages intended to commemorate holidays, events, achievements, and notable historical figures. The first Google Doodle honored the 1998 edition of the long-running annual Burning Man event in Black Rock City, Nevada, and was designed by co-founders Larry Page and Sergey Brin to notify users of their absence in case the servers crashed. Early Marketing employee Susan Wojcicki then spearheaded subsequent Doodles, including an alien landing on Google and additional custom logos for major holidays. Google Doodles were designed by an outside contractor until 2000, when Page and Brin asked public relations officer Dennis Hwang to design a logo for Bastille Day. Since then, a team of employees called "Doodlers" have organized and published the Doodles. Initially, Doodles were neither animated nor hyperlinked—they were simply images with tooltips describing the subject or expressing a holiday greeting. D ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
