hertz

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hertz

(hûrts) [for Heinrich R. HertzHertz, Heinrich Rudolf
, 1857–94, German physicist. He confirmed J. C. Maxwell's electromagnetic theory and in the course of experiments (1886–89) produced and studied electromagnetic waves (known also as hertzian waves, or radio waves).
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], abbr. Hz, unit of frequency, equal to 1 cycle per second. The term is combined with metric prefixes to denote multiple units such as the kilohertz (1,000 Hz), megahertz (1,000,000 Hz), and gigahertz (1,000,000,000 Hz).
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hertz

(herts) Symbol: Hz. The SI unit of frequency, defined as the frequency of a periodic phenomenon that has a period of one second. The frequency range of electromagnetic radiation is about 3000 Hz (very low frequency radio waves) to about 1022 Hz (high-frequency gamma rays).
Collins Dictionary of Astronomy © Market House Books Ltd, 2006

hertz

[hərts]
(physics)
Unit of frequency; a periodic oscillation has a frequency of n hertz if in 1 second it goes through n cycles. Also known as cycle per second (cps). Symbolized Hz.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.

hertz

A unit of frequency, abbr. Hz; one cycle per second.
McGraw-Hill Dictionary of Architecture and Construction. Copyright © 2003 by McGraw-Hill Companies, Inc.

hertz

hertz
The frequency of any cyclic repetition. One hertz (Hz) is one cycle per second. The number of cycles per second is expressed in hertz. Kilohertz (kHz) is a frequency of one thousand cycles per second. Megahertz (MHz) is a frequency of one million cycles per second. The term is named after Heinrich Hertz, a German physicist (1857–1894). Also called a cycle.
An Illustrated Dictionary of Aviation Copyright © 2005 by The McGraw-Hill Companies, Inc. All rights reserved

hertz

the derived SI unit of frequency; the frequency of a periodic phenomenon that has a periodic time of 1 second; 1 cycle per second.

Hertz

1. Gustav . 1887--1975, German atomic physicist. He provided evidence for the quantum theory by his research with Franck on the effects produced by bombarding atoms with electrons: they shared the Nobel prize for physics (1925)
2. Heinrich Rudolph . 1857--94, German physicist. He was the first to produce electromagnetic waves artificially
Collins Discovery Encyclopedia, 1st edition © HarperCollins Publishers 2005

Hertz

Abbreviated "Hz," one Hertz is equal to one cycle per second. In 1883, Heinrich Hertz detected electromagnetic waves, and his name was adopted to measure the number of electromagnetic waves, or cycles, in a signal.

Hertz is widely used to refer to the clock rate of a CPU; for example, 2 GHz means two billion cycles per second. The term is also used for other repeating cycles such as frame rate; for example, a 60 Hz TV displays 60 frames per second. See MHz, GHz and space/time.

The Computer's Heart
Coincidentally, Heinrich Hertz's last name actually means "heart" in German, and the clock is like the computer's heart. It activates everything by pumping pulses into the circuits (see clock).


A 2.25 MHz Clock
The first commercial computer in the 1950s, the UNIVAC I's CPU, which you could literally walk into, had a 2.25 MHz clock that generated 2.25 million pulses per second. Today's computer clocks are a thousand times faster. (Image courtesy of Deutsches Museum, Munich, Archives, R2931.)
Copyright © 1981-2019 by The Computer Language Company Inc. All Rights reserved. THIS DEFINITION IS FOR PERSONAL USE ONLY. All other reproduction is strictly prohibited without permission from the publisher.
References in periodicals archive ?
His cardiac enzyme was normal and electrocardiogram showed giant negative T-waves. He was treated as unstable angina and was then subjected to a line of diagnostic procedures including coronary angiogram before he subsequently underwent ventriculogram which reveal a characteristic 'spade-like' configuration over the left ventricle, in keeping with the diagnosis of ApHCM.
Our findings are corroborated by a systematic review and meta-analysis by Qaddoura et al, in which ECG signs that were good predictors of a negative outcome for in-hospital mortality included S1Q3T3 (OR: 3.38, 95% CI: 2.46-4.66, p<0.001), complete right bundle branch block (OR: 3.90, 95% CI: 2.46-6.20, p<0.001), T-wave inversion (OR: 1.62, 95% CI: 1.19-2.21, p=0.002), right axis deviation (OR: 3.24, 95% CI: 1.86-5.64, p<0.001), and atrial fibrillation (OR: 1.96, 95% CI: 1.45-2.67, p<0.001)18.
Type 2 and 3 are described as "saddle-back" because of an upright T-wave. Types 2 and 3 have ST segment elevations of >1 and <1 mm, respectively.
Out of the 696 leads obtained, 71 leads had to be excluded from analysis because of the poor T-wave formation and presence of U waves.
Fijorek et al., "T-wave inversion in patients with acute pulmonary embolism: Prognostic value," Heart & Lung: The Journal of Acute and Critical Care, vol.
Complete delineation of the ECG allows evaluating not only the HRV but also the PR interval and P-wave duration in order to analyze atria activation and QRS complex with the aim of evaluating ventricular depolarization and QT interval for measuring ventricular depolarization and repolarization jointly and T-wave peak-to-end interval to quantify transmural ventricular repolarization.
Apicobasal gradient of left ventricular myocardial edema underlies transient T-wave inversion and QT interval prolongation (Wellens' ECG pattern) in Takotsubo cardiomyopathy.
His post-cardioversion ECG showed persistent T-wave inversions in leads [V.sub.1], [V.sub.2], and [V.sub.3] as well as epsilon waves [Figure 2].
Especially, the determination of T-wave end is the paramount problem to be solved.The developed method was performed to find the beginning of QRS complexes and the end of T-wave.