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Topic: Radiation resistance

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	Encyclopedia: Radiation resistance (Site not responding. Last check: 2007-10-20)
		Radiation resistance is that part of an antenna's feedpoint resistance that is caused by the radiation of electromagnetic waves from the antenna.
		The radiation resistance is determined by the geometry of the antenna, not by the materials of which it is made.
		While the energy lost by ohmic resistance is converted to heat, the energy lost by radiation resistance is converted to electromagnetic radiation.
	www.nationmaster.com /encyclopedia/Radiation-resistance (214 words)

	Radiation resistance (Site not responding. Last check: 2007-10-20)
		Radiation resistance and loss resistance (which typically causes heating) together are measured as total resistance.
		The Dutch Resistance and the OSS The little known story of the Melanie Mission and the resistance during Market-Garden.
		Foundation War and Resistance Documentation A foundation that documents the resistance movement in the city and province of Groningen.
	www.serebella.com /encyclopedia/article-Radiation_resistance.html (452 words)

	Small antennas and radiation resistance
		Radiation resistance is probably the most abused and misused term in antennas.
		Radiation resistance is purely a function of the effective current distribution and height of the radiator, and is limited by height (spatial length)!
		Radiation resistance, or at least the useful definition of radiation resistance, is limited by spatial area (or height in the case of a vertical) any antenna occupies.
	www.w8ji.com /radiation_resistance.htm (2474 words)

	MWA Antenna Handbook: Appendix A (Site not responding. Last check: 2007-10-20)
		"Radiation resistance" (not to be confused with impedance) refers to the energy absorbed into free space from the antenna circuit.
		A higher radiation resistance indicates more energy is being radiated into space.
		Example: Radiation resistance is 2 ohms, ground loss is 3 ohms, and loading coil loss is 2 ohms.
	www.part15.us /encyclopedia/antenna/appendixa.html (234 words)

	(Radiation Sterilization) Polymer Materials Selection for Radiation-Sterilized Products (MDDI archive, Feb 00)
		Ionizing radiation is a unique and powerful means of modifying polymers, particularly since the changes occur when materials are in a solid state, as opposed to chemical or thermal reactions carried out in hot or melted polymers.
		Radiation effects on the properties of a polymer can also be difficult to predict, especially in the presence of certain additives that can help to prevent radiation damage to plastics.
		Information derived from government, industrial, and scientific studies and publications concerning radiation effects on polymer properties after exposure to various doses is summarized in Figures 1 and 2, which graphically display the dose at which a number of common thermoplastics and thermosets experience a 25% loss in elongation.
	www.devicelink.com /mddi/archive/00/02/006.html (2311 words)

	Radiation resistance
		In the case of radiation, R is an assumed resistance; if this resistance were actually present, it would dissipate the same amount of power that the antenna takes to radiate the energy.
		Note the great difference in the shape of the radiation pattern when it is transferred from the rectangular-coordinate graph in view A to the polar-coordinate graph in view B. The scale of radiation values used in both graphs is identical, and the measurements taken are both the same.
		Radiation from a light source and radiation from an antenna are both forms of electromagnetic waves.
	www.tpub.com /neets/book10/42d.htm (1648 words)

	The radiation impedance of a wire antenna
		If one does this one finds that the radiation resistance for a thin half wave dipole is about 73 ohms, with a reactive part that depends sensitively on the dipole rod diameter, of a few tens of ohms.
		It is for this reason that short antennas are very inefficient radiators; not only do they have low radiation resistance and require more current drive, but they present a serious mismatch to the resistive characteristic impedance of the feeder.
		The radiation resistance measured at the antenna terminals is really an indication of the effectiveness of the antenna structure as a radiator.
	www.ee.surrey.ac.uk /Personal/D.Jefferies/radimp.html (1196 words)

	Fallout @ GameBanshee
		Radiation is something that any vault-dweller must be concerned with.
		While it is normal for a small amount of roentgens, or rads, to enter the normal person during the normal year of activity (more if activities include mountain expeditions and/or high altitude ballooning), a large amount of rad poisoning is a reason for concern.
		With any exposure to radiation, your radiation resistance will reduce the total amount of rads you take by it’s percentage.
	www.gamebanshee.com /fallout/derivedstatistics/radiationresistance.php (122 words)

	Antennas
		The efficiency and gain are limited by resistive losses in the antenna structure, and by resistive loss in objects which may lie inside the "near field" region of the antenna.
		The effective isotropic radiated power (e.i.r.p.) of the antenna is the power which would have to be radiated by an isotropic source to give the same field strength as the real antenna under consideration, on boresight.
		There is an argument that the radiation resistance which "matters" is the driving point resistance; however, we then find that this is critically dependent on the gap capacitance and varies with the spacing of the rods, and whether they are made from solid metal or tubes.
	www.ee.surrey.ac.uk /Personal/D.Jefferies/antennas.html (9048 words)

	Combining Angiostatin With Radiation Enhances Anti-Cancer Effects Of Each
		The researchers also studied the combination of radiation plus mouse angiostatin against human cancers of the brain, head and neck, and prostate that had been transplanted into mice.
		Radiation kills tumor cells but was not expected to alter tumor blood-vessel formation.
		Although cancer cells mutate frequently, enabling them to build up radiation resistance, the vessels that feed these tumors are genetically stable and therefore far less likely to develop resistance.
	www.eurekalert.org /pub_releases/1998-07/UoCM-CAWR-160798.php (572 words)

	Re: help about energy sucking antennas
		Radiation resistance is an important figure inherent to any antenna.
		The value of radiation resistance depends on many factors, such as antenna geometry, frequency, nearby objects, etc. In the case of an ideal half wave dipole antenna, the radiation resistance is about 72 ohms.
		As negative resistance is increased, the Q of the circuit increases, and the bandwidth decreases.
	www.madsci.org /posts/archives/Mar2003/1047390972.Ph.r.html (1262 words)

	Silicone Rubber Radiation Resistance - Dow Corning (Site not responding. Last check: 2007-10-20)
		As the total radiation dose is increased, hardness of the rubber increases; tensile strength may increase at first, but later decreases sharply; elongation decreases.
		These direct effects of radiation are proportional to the total amount of radiation level - as long as the radiation level is low or moderate.
		Data is given for radiation exposure to a cobalt-60 source at room temperature and at 200 °C. The level of 50 percent elongation is arbitrarily used as the test endpoint because, for many applications, this is the minimum amount of rubberiness that an elastomer can have and still be useful.
	www.dowcorning.com /content/rubber/rubberprop/rubber_radiation.asp (239 words)

	RADIATION RESISTANCE
		radiation pattern and electrical characteristics of the antenna are practically unaffected by the presence of
		Radiation resistance varies at different points on the antenna.
		radiation pattern is a plot of the radiated energy from an antenna.
	www.tpub.com /content/neets/14182/css/14182_178.htm (485 words)

	ARRLWeb: Why an Antenna Radiates (Site not responding. Last check: 2007-10-20)
		The figure is a snapshot of the electron's radiation field taken at an instant when the electron is at the center of its travel and moving to the right, as indicated by an arrow.
		Radiation resistance varies along the length of an antenna wire, but it is independent of the diameter and material of the conductor.
		If the ohmic resistance is small enough to be ignored, the coulomb field is precisely equal and opposite to the dynamic electric field everywhere on the surface of an antenna.
	www.arrl.org /tis/info/whyantradiates.html (4699 words)

	DNA in dormant Bacillus subtilis spores exposed to artificial UV-C, UV-B or solar radiation accumulates strand breaks ...
		Resistance of spores lacking inner, outer, or both spore coat layers to UV radiation from artificial or natural sources.
		The resistance of bacterial spores to solar UV is the sum of a number of protective, photochemical, and repair mechanisms.
		DNA repair and the ultraviolet radiation resistance of bacterial spores: from the laboratory to the environment.
	www.photobiology.com /photobiology2000/nichol (2663 words)

	Blocking pathway overcomes tumor vessel resistance to radiation
		The radiation therapy intended to kill the blood vessels that feed cancer cells can actually trigger a chemical pathway that makes the vessels more resistant to therapy.
		We were surprised to find that cell survival pathways were activated not only by these growth factors but by the therapy itself." Blood vessels probably developed this mechanism, Hallahan said, to protect themselves against the day-to-day exposure to so-called "free radicals" produced as a byproduct of inflammation and other normal biologic processes.
		The researchers found that radiation activates a biochemical signalling pathway involving the proteins known as PI3K and Akt.
	www.eurekalert.org /pub_releases/2002-08/vumc-bpo082602.php (535 words)

	ARS \| Publication request: Nalidixic Acid Resistance Increases Sensitivity of Escherichia Coli O157:h7 to Ionizing ...
		The response to ionizing radiation was determined for these six strains in a phosphate buffer solution and on green leaf lettuce.
		The differences in radiation sensitivity between antibiotic-resistant and antibiotic-sensitive strains depended on the isolate and the suspending medium (buffer or lettuce).
		The resistance to ionizing radiation of the parent and Nal-R strains was determined in Butterfield's phosphate buffer solution and on green leaf lettuce.
	www.ars.usda.gov /research/publications/publications.htm?SEQ_NO_115=168888 (372 words)

	Radiation Nation
		Increased radiation resistance was an early addition to the human genome, found in practically all extant clades.
		The drawback is an increase in energy needs, but for individuals living in technological societies this is not a problem (among formerly technological societies, such as Version War Klarus, there is a detectable selection effect against this radiation resistance as bearers of the gene prove less starvation resistant).
		Radiation Nation emerged in the 5000's as a synclade of other clades identifying themselves strongly with radiation resistance, often extending it far beyond the levels ordinary used among mainstream clades.
	www.orionsarm.com /clades/Radiation_Nation.html (305 words)

	[No title]
		Difficulty in developing radiation resistance clones of the cell types of interest has compounded the problem of identifying the mechanism(s) responsible for inherent radiation resistance.
		A common feature of the stress response of cells induced by ionizing radiation is the introduction or activation of proteins believed to protect the cell against killing.
		By better understanding the radiation resistance associated with human tumor cells, it may be possible to modulate those mechanisms identified as playing significant roles and thereby significantly improve the clinical effect of radiation therapy.
	www.ibiblio.org /pub/docs/nih-nsf/rfaca-92-03.911122 (2265 words)

	[No title] (Site not responding. Last check: 2007-10-20)
		This study marks the first time that an in vitro radiation resistance assay and Oncotech's Extreme Drug Resistance (EDR(R)) Assay will be used in combination.
		The primary objective of this prospective study is to investigate the association of the Radiation Resistance Assay results with patients' progression-free survival.
		Many of those 470,000 patients could be resistant to combination chemotherapy/radiation regimens but their physicians would not know this until treatment had already begun.
	www.acor.org /drugs/pipeline/news/parsed/6955715.news (517 words)

	Genome Biology \| Research news
		The genetic apparatus underlying the susceptibility of a cell to ionizing radiation has become clearer, with the discovery of 107 new genes associated with this cellular response mechanism.
		A screen of mutant yeast cells identified 107 new genes that affect sensitivity to ionizing radiation.
		They were quite surprised to find that nearly 25% of the radiation-sensitive mutants were resistant to the anti-cancer drug bleomycin, which causes breaks in the DNA similar to those caused by radiation.
	www.genomebiology.com /researchnews/default.asp?arx_id=gb-spotlight-20011129-01 (689 words)

	Gene vital to radiation resistance in bacteria
		With a name that literally means "strange berry that can withstand radiation," D. radiodurans is the world's most radiation resistant organism, able to survive up to 1.5 million rads, over 1000 times more radiation than practically any other organism.
		To better define the mechanisms used by the bacterium to resist radiation, Earl and her team, which included researchers from The Institute for Genomic Research (TIGR), studied a mutant strain of D. radiodurans that could not survive high radiation levels.
		When the irrE gene was restored, the bacterium was once again resistant to radiation, a finding that suggested the gene was responsible, at least in some part, for resistance.
	www.eurekalert.org /pub_releases/2003-01/asfm-gvt012803.php (549 words)

	Electromagnetic Radiation Explained - by Jim Hawkins (WA2WHV)
		In order for radiation to be able to occur, we have to prove that magnetic and electric fields can exist without the presence of a nearby current and that these fields will "move" through space.
		When the voltage and current are observed at the terminals of a radiating conductor or antenna, one component of alternating current is 90 degrees out of phase with the alternating voltage and another component is in phase with the alternating voltage.
		That portion of drag, due to the dynamic or radiated electric field is the force of radiation resistance.
	hawkins.pair.com /eRadiation.html (2720 words)

	Role of the Spore Coat Layers in Bacillus subtilis Spore Resistance to Hydrogen Peroxide, Artificial UV-C, UV-B, and ... (Site not responding. Last check: 2007-10-20)
		Resistance to lysozyme is the traditional method used to assess the integrity of the spore coat layers (6, 21, 56);
		Summary of the UV resistance of spores of coat mutant strains normalized to the resistance of the wild-type strain.
		Tanooka, H. Ultraviolet resistance of DNA in spore spheroplast of Bacillus subtilis as measured by the transforming activity.
	aem.asm.org /cgi/content/full/66/2/620 (5323 words)

	HITEN DHARAVAT (Site not responding. Last check: 2007-10-20)
		Electronic components are used in natural radiation environment as well as in the ionizing radiation environment for research purposes.
		Hence, it is important to know the radiation tolerance or resistance of COTS components before they can be used in any kind of radiation environment.
		If maximum possible total dose in the radiation environment where the electronic chip is going to be used does not exceed the failure dose then a COTS component can be preferred over its rad-hard version, as it is relatively inexpensive and is easily available in bulk.
	web.umr.edu /~tfsl/Tokuhiro/hiten.html (411 words)

	ARS \| Publication request: Radiation (Gamma) Resistance and Post-Irradiation Growth of Listeria Monoctytogenes ...
		SDA/PL increased the radiation sensitivity of L. monocytogenes in bologna and prevented the growth of the microorganism during long-term refrigerated storage.
		The radiation resistance of Lm, and its ability to proliferate during long-term refrigerated storage (9 degrees C), when inoculated into beef bologna that contained no SDA/PL, 0.07 percent SDA/1 percent PL, and 0.15 percent SDA/2 percent PL, was determined.
		The D-10 value, the radiation dose required to eliminate 90 percent of viable Lm, was 0.56 kGy on 0 percent SDA/PL bologna, 0.53 kGy on 0.07 percent SDA/1 percent PL bologna, and 0.46 kGy on 0.15 percent SDA/2 percent PL bologna.
	www.ars.usda.gov /research/publications/publications.htm?SEQ_NO_115=141083 (379 words)

	Radiation resistance secrets un-covered? (Site not responding. Last check: 2007-10-20)
		This dose of radiation shreds the bacteria's genome into hundreds of pieces.
		The organism's remarkable ability to repair this DNA damage completely in a day and go on living offers researchers tantalizing clues to better understanding the mechanism of cellular repair.
		Typically, it is found in locations where most other bacteria have died from extreme conditions, ranging from the shielding pond of a radioactive cesium source to the surfaces of Arctic rocks.
	www.naturalworldtours.co.uk /article/november271999c.htm (782 words)

	NEW MATERIALS WITH INCREASED RADIATION RESISTANCE (Site not responding. Last check: 2007-10-20)
		The Institute for Metal Physics has developed novel efficiently alloyed stainless austenitic steels type Cr16Ni15Mn3Ti1, which are resistant against radiation- induced swelling, creep, and embrittlement.
		Increasing resistance to radiation-induced deformation at large fluences is accomplished by special alloying of titanium, followed by cold deformation or thermomechanical treatment.
		Using the new reactor steel largely increases the combustion of the reactor fuel (for heavy atoms), up to 14% and more, thereby increasing the ecological reliability of the atomic power station owing to a decrease in the degree of cracking of fuel element claddings.
	www.imp.uran.ru /info/innovation/Medved-8.html (206 words)

	Genomes of Tiny Microbes Yield Clues to Global Climate Change
		In the past, researchers have suggested that this microbe's extraordinary hardiness might be related to the unusual ring-like structure of its genome or the 4-8 genome copies carried by each cell.
		Daly and colleagues now show that chromosome organization is unlikely to play a role in radiation resistance and that a high concentration of manganese ions relative to iron ions is essential to its ability to survive gamma radiation.
		The authors suggest that the manganese may not provide protection from the initial radiation; rather, it protects cells against harmful reactive oxygen species that accumulate during the recovery from radiation.
	www.doegenomestolife.org /news/radiation093004.shtml (230 words)

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