# resistance

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Related to antiviral resistance: Resistance to antiviral drugs

## resistance,

property of an electric conductor by which it opposes a flow of electricity and dissipates electrical energy away from the circuit, usually as heat. Optimum resistance is provided by a conductor that is long, small in cross section, and of a material that conducts poorly. Resistance is basically the same for alternating and direct current circuits (see impedanceimpedance,
in electricity, measure in ohms of the degree to which an electric circuit resists the flow of electric current when a voltage is impressed across its terminals.
). However, an alternating current of high frequency tends to travel near the surface of a conductor. Since such a current uses less of the available cross section of the conductor than a direct current, it meets with more resistance than a direct current. In circuit analysis an ideal resistorresistor,
two-terminal electric circuit component that offers opposition to an electric current. Resistors are normally designed and operated so that, with varying levels of current, variations of their resistance values are negligible (see resistance).
, i.e., a circuit component whose only property is resistance, is called a resistance. The phenomenon of resistance arises from the interactions of electrons with ions in the conductor. The unit of resistance is the ohmohm
[for G. S. Ohm], symbol Ω, unit of electrical resistance, defined as the resistance in a circuit in which a potential difference of one volt creates a current of one ampere; hence, 1 ohm equals 1 volt/ampere. The megohm (1,000,000 ohms) and the milliohm (.
. See superconductivitysuperconductivity,
abnormally high electrical conductivity of certain substances. The phenomenon was discovered in 1911 by Heike Kamerlingh Onnes, who found that the resistance of mercury dropped suddenly to zero at a temperature of about 4.
; Ohm's lawOhm's law
[for G. S. Ohm], law stating that the electric current i flowing through a given resistance r is equal to the applied voltage v divided by the resistance, or i=v/r.
; conductionconduction,
transfer of heat or electricity through a substance, resulting from a difference in temperature between different parts of the substance, in the case of heat, or from a difference in electric potential, in the case of electricity.
.

## resistance,

in biology: see immunityimmunity,
ability of an organism to resist disease by identifying and destroying foreign substances or organisms. Although all animals have some immune capabilities, little is known about nonmammalian immunity.
.

## resistance,

in psychiatry: see psychoanalysispsychoanalysis,
name given by Sigmund Freud to a system of interpretation and therapeutic treatment of psychological disorders. Psychoanalysis began after Freud studied (1885–86) with the French neurologist J. M.
.

## Resistance

The physical property of a material to resist or impede the conduction of electrical current, measured in ohms. High resistance means poor conductivity and vice versa.

## resistance

[ri′zis·təns]
(acoustics)
(electricity)
The opposition that a device or material offers to the flow of direct current, equal to the voltage drop across the element divided by the current through the element. Also known as electrical resistance.
In an alternating-current circuit, the real part of the complex impedance.
(fluid mechanics)
(mechanics)
In damped harmonic motion, the ratio of the frictional resistive force to the speed. Also known as damping coefficient; damping constant; mechanical resistance.

## electrical resistance

The physical property of a device, conductor, element, branch, or system, by virtue of which power is lost as heat when current flows through it; the physical property which an electric conductor exhibits to the flow of current; measured in ohms.

## resistance

1.
a. the opposition to a flow of electric current through a circuit component, medium, or substance. It is the magnitude of the real part of the impedance and is measured in ohms.
b. (as modifier): resistance coupling
2. any force that tends to retard or oppose motion
3. (in psychoanalytical theory) the tendency of a person to prevent the translation of repressed thoughts and ideas from the unconscious to the conscious and esp to resist the analyst's attempt to bring this about
4. Physics the magnitude of the real part of the acoustic or mechanical impedance
References in periodicals archive ?
1] Additional members of the US Antiviral Resistance Surveillance Working Group who contributed data are listed at the end of this article.
Among 1,982 national surveillance oseltamivir-susceptible specimens from the 16 FluSurv-NET states, 1,607 (81%) had county information; among these, 401 (25%) specimens were from FluSurv-NET counties, and 65 patients from FluSurv-NET were high probability matches to patients identified in antiviral resistance surveillance data (Table).
Public health laboratories are requested to submit 1) summer specimens, 2) any specimens that cannot be subtyped by standard methods, or 3) specimens that are otherwise unusual, to CDC for further antigenic characterization, antiviral resistance monitoring, and identification of novel influenza A viruses.
Developed in ViraCor's laboratories, the molecular test accurately detects key genetic mutations associated with antiviral resistance in CMV in three days or less.
Antiviral resistance and the control of pandemic influenza.
Exclusive access to molecular-based technologies for influenza B diagnostics, and for detection of antiviral resistance, greatly complements our ongoing progress with our MChip technology for influenza A, which was licensed in December 2006 from CU-Boulder.
Monitoring of antiviral resistance among influenza isolates showed that resistance pattern changed among subtype H1N1 viruses when different lineages were introduced.
This indicates that antiviral resistance to ATC does not occur quickly and gives ATC a significant competitive advantage over several other drugs which can rapidly select for resistance.
Health-care providers should be aware that antiviral resistance can develop during chemoprophylaxis or treatment with subtherapeutic dosages and should follow published recommendations for antiviral medications (5).
Other articles address timely and important issues such as vaccine development and antiviral resistance.
Because of prolonged shedding of novel influenza A (H1N1) virus and suspected oseltamivir resistance, nasal wash specimens previously collected from the patient were sent to CDC for antiviral resistance testing and arrived on August 5.
However, the main reason they have never been considered for therapy in a pandemic is that antiviral resistance occurs in [greater than or equal to] 30% of those given the drug for treatment and that resistant viruses are fully pathogenic and transmissible (27).

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