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Sample records for parameters effective radiating

  1. Theoretical study of ionization radiation effects on optical fiber parameters

    NASA Astrophysics Data System (ADS)

    Poret, Jay C.; Suter, Joseph J.

    1994-06-01

    The effect of ionizing radiation on various fiber parameters has been examined. It was demonstrated that when the real refractive index increases, the V number increases as does the numerical aperture. The percentage of power propagating in the cladding decreases with increasing real refractive index. Small changes in the refractive index will induce additional modes to form. The effect of radiation on fiber dispersion was reasoned to be negligible for short lengths of fibers (< 2 km).

  2. Fundamental radiation effects parameters in metals and ceramics

    SciTech Connect

    Zinkle, S.J.

    1998-03-01

    Useful information on defect production and migration can be obtained from examination of the fluence-dependent defect densities in irradiated materials, particularly when a transition from linear to sublinear accumulation is observed. Further work is needed on several intriguing reported radiation effects in metals. The supralinear defect cluster accumulation regime in thin foil irradiated metals needs further experimental confirmation, and the physical mechanisms responsible for its presence need to be established. Radiation hardening and the associated reduction in strain hardening capacity in FCC metals is a serious concern for structural materials. In general, the loss of strain hardening capacity is associated with dislocation channeling, which occurs when a high density of small defect clusters are produced (stainless steel irradiated near room temperature is a notable exception). Detailed investigations of the effect of defect cluster density and other physical parameters such as stacking fault energy on dislocation channeling are needed. Although it is clearly established that radiation hardening depends on the grain size (radiation-modified Hall-Petch effect), further work is needed to identify the physical mechanisms. In addition, there is a need for improved hardening superposition models when a range of different obstacle strengths are present. Due to a lack of information on point defect diffusivities and the increased complexity of radiation effects in ceramics compared to metals, many fundamental radiation effects parameters in ceramics have yet to be determined. Optical spectroscopy data suggest that the oxygen monovacancy and freely migrating interstitial fraction in fission neutron irradiated MgO and Al{sub 2}O{sub 3} are {approximately}10% of the NRT displacement value. Ionization induced diffusion can strongly influence microstructural evolution in ceramics. Therefore, fundamental data on ceramics obtained from highly ionizing radiation sources

  3. Alternative Physical Quality Parameters Influences Effectiveness of Lower Doses Ionizing Radiation

    NASA Astrophysics Data System (ADS)

    Yousif, Abubaker Ali; Bahari, Ismail Bin; Yasir, Muhamad Samudi

    2011-03-01

    It has been proved in many studied that the absorbed dose is not good physical quality parameter to quantify the radiation effects at lower doses. However relative biological effect (RBE) is still used as a major parameter of radiation effectiveness. Whereas linear energy transfer (LET) is inadequate physical parameter, therefore the weaknesses in using RBE-LET system for radiation protection have been investigated. Secondary data of V79 has reanalyzed to help complement the inadequacy current method in assessing cell inactivation at lower doses. Results of analysis show that the effectiveness of densely ionizing radiation is better quantified using mean free path (λ).

  4. The effect of neutron radiation on the photoelectric parameters of ITO-GaSe structures

    SciTech Connect

    Kovalyuk, Z. D. Litovchenko, P. G.; Politanska, O. A.; Sydor, O. N.; Katerynchuk, V. N.; Lastovetsky, V. F.; Litovchenko, O. P.; Dubovoy, V. K.; Polivtsev, L. A.

    2007-05-15

    The effect of 1-MeV neutrons on the photoelectric parameters of ITO-GaSe heterostructures was studied. It is shown that the observed variations in the current-voltage characteristics are caused by the effect of penetrating radiation on both components of the structure, which brings about an increase in the resistance of the heterostructures. The presence of exciton fine structure in the photosensitivity spectra after irradiation indicates that GaSe retains high structural quality notwithstanding the introduced radiation defects. The results obtained are accounted for by spatial redistribution of doping impurity in GaSe and structural changes in the ITO films.

  5. Effect of radiation and thermal treatment on structural and transport parameters for cellulose regenerated membranes

    NASA Astrophysics Data System (ADS)

    Váquez, M. I.; Galán, P.; Casado, J.; Ariza, M. J.; Benavente, J.

    2004-11-01

    Modifications caused by different types of ionizing radiation and thermal treatment on transport, chemical and structural parameters of polymeric (regenerated cellulose) membranes have been studied. Particularly, the effect of different types of radiation (ultraviolet light (UV) and ionising radiation (Ir) with different doses) and heating at 60 °C on transport and electrical parameters for a cellophane membrane has been considered by determining salt permeability and electrical resistance for the different samples. These parameters were obtained from salt diffusion and impedance spectroscopy (IS) measurements with the membranes in contact with NaCl solutions at different concentrations. Chemical surface and structural modifications of the polymer matrix due to the treatments have also been determined by X-ray photoelectron spectroscopy (XPS) and infrared spectroscopy (ATR mode). Results obtained from infrared spectroscopy seem to indicate that ionising radiation modifies the proportion of OH links, which is related to the dose of irradiation. XPS analysis only shows small differences in the atomic concentration and shape of the C 1s spectra. On the other hand, an increase of salt permeability for heated and UV-treated membranes was obtained, while this parameter decreases in the case of irradiated membranes. This result could be related to a change in the packing of the polymer chains, which results in an increase of the fractional void volume in the case of heat- and UV-treated membranes and the opposite effect for the irradiated ones; for these latter, a correlation between the irradiation dose and the decrease in permeability values was also obtained. IS results show a decrease in the electrical resistance of all treated samples. This fact can be due to the most open structure of heated and UV-treated samples, previously indicated; however, due to the closer structure assumed for the irradiated sample, this point might be related to the presence of free

  6. Radiation processing of thermoplastic starch by blending aromatic additives: Effect of blend composition and radiation parameters

    NASA Astrophysics Data System (ADS)

    Khandal, Dhriti; Mikus, Pierre-Yves; Dole, Patrice; Coqueret, Xavier

    2013-03-01

    This paper reports on the effects of electron beam (EB) irradiation on poly α-1,4-glucose oligomers (maltodextrins) in the presence of water and of various aromatic additives, as model blends for gaining a better understanding at a molecular level the modifications occurring in amorphous starch-lignin blends submitted to ionizing irradiation for improving the properties of this type of bio-based thermoplastic material. A series of aromatic compounds, namely p-methoxy benzyl alcohol, benzene dimethanol, cinnamyl alcohol and some related carboxylic acids namely cinnamic acid, coumaric acid, and ferulic acid, was thus studied for assessing the ability of each additive to counteract chain scission of the polysaccharide and induce interchain covalent linkages. Gel formation in EB-irradiated blends comprising of maltodextrin was shown to be dependent on three main factors: the type of aromatic additive, presence of glycerol, and irradiation dose. The chain scission versus grafting phenomenon as a function of blend composition and dose were studied using Size Exclusion Chromatography by determining the changes in molecular weight distribution (MWD) from Refractive Index (RI) chromatograms and the presence of aromatic grafts onto the maltodextrin chains from UV chromatograms. The occurrence of crosslinking was quantified by gel fraction measurements allowing for ranking the cross-linking efficiency of the additives. When applying the method to destructurized starch blends, gel formation was also shown to be strongly affected by the moisture content of the sample submitted to irradiation. The results demonstrate the possibility to tune the reactivity of tailored blend for minimizing chain degradation and control the degree of cross-linking.

  7. Incident Wire Array Z-pinch Plasma Radiation Fluence Effects on the Filter Material Property & Implications on the Observed Radiation Parameters

    NASA Astrophysics Data System (ADS)

    Chong, Y. K.; Thornhill, J.; Velikovich, A.; Giuliani, J.; Davis, J.; Clark, R.; Ampleford, D.; Coverdale, C.; Jones, B.

    2010-11-01

    The wire array Z-pinches on the refurb. Z are marked by an intense bright emission of high energy non-LTE photons. In order to diagnose the radiation in such a hostile environment, a number of materials w/ varying composition are used to provide select optimized radiation filtering. Traditionally, the various radiation parameters are determined from the deconvolution of the actual observed values using an appropriate time invariant filter response function (FRF). Under exposure to the radiation, however, the materials may undergo significant changes. We examine the response of various filters to an intense radiation from the plasmas. A MHD+multifreq. rad. x-port code is employed to establish the time varying non-LTE radiation & to investigate the evolution of the materials subject to the field. A characterization of the material EOS/FRF is made & their effect on the radiation characteristics are quantified w/ a goal of optimized filter design/deployment.

  8. Effect of extreme radiation fluences on parameters of SiC nuclear particle detectors

    SciTech Connect

    Ivanov, A. M. Lebedev, A. A.; Strokan, N. B.

    2006-10-15

    Detectors based on modern CVD-grown films were irradiated with 8 MeV protons at a fluence of 3 x 10{sup 14} cm{sup -2}. The concentration of primary radiation defects was {approx}10{sup 17} cm{sup -3}, which is three orders of magnitude higher than the concentration of the initially present uncompensated donors. The resulting deep compensation of SiC enabled measurements of detector parameters in two modes: under reverse and forward bias. The basic parameters of the detectors degraded by no more than a factor of 1.7, compared with the fluence of 1 x 10{sup 14} cm{sup -2}. However, there appeared a polarization voltage, which indicates that a space charge is accumulated by radiation defects.

  9. Effects of Solar Particle Event Proton Radiation on Parameters Related to Ferret Emesis

    PubMed Central

    Sanzari, J. K.; Wan, X. S.; Krigsfeld, G. S.; King, G. L.; Miller, A.; Mick, R.; Gridley, D. S.; Wroe, A. J.; Rightnar, S.; Dolney, D.; Kennedy, A. R.

    2013-01-01

    The effectiveness of simulated solar particle event (SPE) proton radiation to induce retching and vomiting was evaluated in the ferret experimental animal model. The endpoints measured in the study included: (1) the fraction of animals that retched or vomited, (2) the number of retches or vomits observed, (3) the latency period before the first retch or vomit and (4) the duration between the first and last retching or vomiting events. The results demonstrated that γ ray and proton irradiation delivered at a high dose rate of 0.5 Gy/min induced dose-dependent changes in the endpoints related to retching and vomiting. The minimum radiation doses required to induce statistically significant changes in retching- and vomiting-related endpoints were 0.75 and 1.0 Gy, respectively, and the relative biological effectiveness (RBE) of proton radiation at the high dose rate did not significantly differ from 1. Similar but less consistent and smaller changes in the retching- and vomiting-related endpoints were observed for groups irradiated with γ rays and protons delivered at a low dose rate of 0.5 Gy/h. Since this low dose rate is similar to a radiation dose rate expected during a SPE, these results suggest that the risk of SPE radiation-induced vomiting is low and may reach statistical significance only when the radiation dose reaches 1 Gy or higher. PMID:23883319

  10. Effects of Ionizing Radiation on Respiratory Function Tests and Blood Parameters in Radiology Staff

    PubMed Central

    Saygin, M; Yasar, S; Kayan, M; Balci, UG; Öngel, K

    2014-01-01

    Aim: To evaluate pulmonary function tests and blood parameters and their relationship with sociodemographic data for radiology staff continuously exposed to ionizing radiation. Subjects and Method: Thirty-eight personnel from Suleyman Demirel University Training and Research Hospital, Radiology Unit, were included in this study. Sociodemographic data were evaluated by a questionnare that was developed by the researchers. Height and weight measurements were performed with a standard scale and meter. Routine blood parameters and spirometric lung function measurements of the cases were recorded. Statistical significances were determined by independent t-test, analysis of variance (ANOVA), bivariate correlation and Kruskal-Wallis tests using SPSS 18.0. Results: The mean age was 32.42 ± 5.5 years; 19 patients (50%) were male and 19 patients (50%) were female. Body mass index (BMI) was calculated as 25.68 ± 0.47 for men and 24.58 ± 1.13 for women. Forced vital capacity (FVC), forced expiratory volume in the 1st second (FEV1), peak expiratory flow (PEF) and maximum mid-expiratory flow (FEF25-75) showed statistically significant differences between gender (p < 0.01). In addition, FEV1 and FEF25-75 also demonstrated statistically negatively significant difference with the type of task (p < 0.05). A statistically significant negative difference was found between FEF25-75 value and time to start smoking (p < 0.05). Among FVC, FEV1, PEF and FEF25-75 values and alcohol usage, statistically significant positive difference was detected (p < 0.05). Statistically significant positive difference was found among FVC, PEF and FEF25-75 values and sports activity (p < 0.05). According to BMI groups, statistically significant positive difference with FVC, FEV1 and PEF values were found (p < 0.05). Statistically significant correlations were found among FVC value and haemoglobin level (Hgb), haematocrit level (Hct) and mean corpuscular volume (MCV), among FEV1 value and Hgb, MCV, among

  11. Effects of gamma radiation on Clostridium botulinum type E under various parameters

    SciTech Connect

    Lim, Y.H.

    1986-01-01

    Spores of Clostridium botulinum type E strain Eklund (Eklund) was irradiated with gamma radiation and its recovery was tested on the tryptone-peptone-glucose-yeast extract-agar (TPGYA) containing various levels of NaCl and Na-thioglycollate. The presence of 0.5% or more NaCl in the media decreased the viable counts, while Na-thioglycollate of up to 0.15% did not affect the recovery of both irradiated and non-irradiated spores. Eklund spores were also irradiated under air (21% O/sub 2/), N/sub 2/O and N/sub 2/, with or without the additive of one of the following agents (additive/concentration): disodium ethylenediaminetetraacetate (EDTA), 0.01 M; t-butanol, 0.1 M; NaCl, 0.01 M; catalyze, 10 mg/ml and DL-cysteine, 0.1 mM. Radiation process was most effective in destroying the spores when carried out under air (21% O/sub 2/), followed by N/sub 2/O and N/sub 2/. Among the additives tested, EDTA was the most efficient protector followed by t-butanol when irradiation process was carried under N/sub 2/O and N/sub 2/ gas environment. Catalase and DL-cysteine sensitized the spores when irradiated under N/sub 2/O and N/sub 2/, while NaCl only sensitized under N/sub 2/. Spores kept frozen at -75/sup 0/C for 30 days but thawed prior to irradiation were more sensitive to radiation damage than freshly prepared spores. Radiation resistance of the spores increased when 15% glycerol was added to the phosphate bugger (0.06 M, pH 7.0) and used as suspending media. When the concentration of the spore increased from 10/sup 6//ml to 10/sup 11//ml, the radiosensitivities also increased. Seven strains of C. botulinum type E were screened for plasmids by agarose gel electrophoresis.

  12. Vital parameters related low level laser radiation

    NASA Astrophysics Data System (ADS)

    Palmieri, Beniamino; Capone, Stefania

    2011-08-01

    The first work hypotesis is that biosensors on the patient detecting heart, breath rate and skin parameters, modulate laser radiation to enhance the therapeutic outcome; in the second work hypotesis: biofeedback could be effective, when integrated in the low level laser energy release.

  13. Effect of gamma radiation on the growth, survival, hematology and histological parameters of rainbow trout (Oncorhynchus mykiss) larvae.

    PubMed

    Oujifard, Amin; Amiri, Roghayeh; Shahhosseini, Gholamreza; Davoodi, Reza; Moghaddam, Jamshid Amiri

    2015-08-01

    Effects of low (1, 2.5 and 5Gy) and high doses (10, 20 and 40Gy) of gamma radiation were examined on the growth, survival, blood parameters and morphological changes of the intestines of rainbow trout (Oncorhynchus mykiss) larvae (103±20mg) after 12 weeks of exposure. Negative effects of gamma radiation on growth and survival were observed as radiation level and time increased. Changes were well documented at 10 and 20Gy. All the fish were dead at the dose of 40Gy. In all the treatments, levels of red blood cells (RBC), hematocrit (HCT) and hemoglobin (HB) were significantly (P<0.05) declined as the irradiation levels increased, whereas the amount of mean corpuscular volume (MCV) and mean corpuscular hemoglobin (MCH) did not change. No significant differences (P>0.05) were found in the levels of white blood cells (WBC), lymphocytes and monocytes. Destruction of the intestinal epithelium cells was indicated as the irradiation levels increased to 1Gy and above. The highest levels of growth, survival, specific growth rate (SGR), condition factor (CF) and protein efficiency rate (PER) were obtained in the control treatment. The results showed that gamma rays can be a potential means for damaging rainbow trout cells. PMID:26141584

  14. Effects of Calendula Essential Oil-Based Cream on Biochemical Parameters of Skin of Albino Rats against Ultraviolet B Radiation.

    PubMed

    Mishra, Arun K; Mishra, Amrita; Verma, Anurag; Chattopadhyay, Pronobesh

    2012-09-01

    Reactive oxygen species (ROS) generated from UV-B radiation have the capacity to cause oxidative decomposition which leads to the formation of toxic components as well as lipid peroxidation. Considering this fact, the present study was performed to evaluate the effect of a cream (O/W) containing the essential oil of Calendula officinalis on biochemical parameters of the skin of albino rats against UV-B radiation. The fingerprint analysis of Calendula essential oil was performed by HPLC with special reference to 1,8-cineole and α-pinene. The results indicated that the treatment with creams containing 4% and 5% of Calendula essential oil caused a significant decrease in the malonyldialdehyde level, whereas the levels of catalase, glutathione, superoxide dismutase, ascorbic acid, and the total protein level were significantly increased after 1 month of daily irradiation and treatment when compared to untreated control groups. The results suggest that the cutaneous application of the essential oil of Calendula prevents UV-B-induced alterations in the level of antioxidants in skin tissue. PMID:23008814

  15. Radiation Parameters of Some Potential Bioactive Compounds.

    PubMed

    Gedik, Zeynep; Tugrak, Mehtap; Dastan, Aysenur; Gul, Halise Inci; Yilmaz, Demet

    2015-06-01

    In this study, we aimed to determine the radiation parameters of some potential bioactive compounds. 1-Aryl-3-dibenzylamino-propane-1-on hydrochloride type Mannich bases were synthesized via classical conventional heating method. Aryl part was changed as phenyl (C6H5), 4-methylphenyl (4-CH3C6H4), 4-fluorophenyl ( 4-FC6H4), 4-nitrophenyl (4-NO2C6H4), 4-chlorophenyl (4-ClC6H4), 4-bromophenyl (4-BrC6H4), and 2-thienyl (C4H3S-2-yl). Mass attenuation coefficient (μm), effective atomic number (Z(eff)) and effective electron density (N(el)) of compounds were determined experimentally and theoretically for at 8.040, 8.910, 13.40, 14.96, 17.48, 19.61, 22.16, 24.94, 32.19, 36.38, 44.48, 50.38 and 59.54 keV photon energies by using an HPGe detector with a resolution of 182 eV at 5.9 keV. Radiation parameters of these compounds which can be anti-cancer drug candidate were given in the tables. The results show that phenyl ring behave like thiophene ring in terms of radiation absorption. It is thought that the results of study may drive allow the development of drug candidate new compounds in medical oncology. PMID:26601355

  16. Effects of gamma radiation on the biological, physico-chemical, nutritional and antioxidant parameters of chestnuts - a review.

    PubMed

    Antonio, Amilcar L; Carocho, Márcio; Bento, Albino; Quintana, Begoña; Luisa Botelho, M; Ferreira, Isabel C F R

    2012-09-01

    Gamma radiation has been used as a post-harvest food preservation process for many years. Chestnuts are a seasonal product consumed fresh or processed, and gamma irradiation emerged recently as a possible alternative technology for their post-harvest processing, to fulfil the requirements of international phytosanitary trade laws. After harvest and storage, several problems may occur, such as the presence of infestations and development of microorganisms, namely rotting and fungi. These diminish the quality and safety of the product, decreasing the yield along the production chain. In fruits, gamma irradiation treatment is for two main purposes: conservation (ripening delay) and insect disinfestation (phytosanitary treatment). In this review, the application of gamma irradiation to chestnuts is discussed, including production data, the irradiated species and the effects on biological (sprouting, rotting, respiration rate, insects, worms and fungi), physico-chemical (color, texture, and drying rate), nutritional (energetic value, proteins, sugars and fatty acids) and antioxidant (tocopherols, ascorbic acid, phenolics, flavonoids and antioxidant activity) parameters. These changes are the basis for detecting if the food product has been irradiated or not. The validation of standards used for detection of food irradiation, as applied to chestnuts, is also discussed. PMID:22735498

  17. Chemical Effect on K Shell X-ray Fluorescence Parameters and Radiative Auger Ratios of Co, Ni, Cu, and Zn Complexes

    NASA Astrophysics Data System (ADS)

    Cengiz, Erhan; Bıyıklıoğlu, Zekeriya; Küp Aylıkcı, Nuray; Aylıkcı, Volkan; Apaydın, Gökhan; Tıraşoğlu, Engin; Kantekin, Halit

    2010-04-01

    The production cross-sections, intensity ratios, and radiative Auger intensity ratios of Co, Ni, Cu, and Zn elements in different complexes were measured. The chemical effects on the K shell fluorescence parameters and the radiative Auger intensity ratios of these elements were investigated and the changes in these parameters were interpreted according to the charge transfer process. The samples were excited by 59.5 keV γ-rays from a 241Am annular radioactive source. K X-rays emitted by samples were counted by an Ultra-LEGe detector with a resolution of 150 eV at 5.9 keV.

  18. An analytical method for estimating the {sup 14}N nuclear quadrupole resonance parameters of organic compounds with complex free induction decays for radiation effects studies

    SciTech Connect

    Iselin, L.H.

    1992-12-31

    The use of {sup 14}N nuclear quadrupole resonance (NQR) as a radiation dosimetry tool has only recently been explored. An analytical method for analyzing {sup 14}N NQR complex free induction decays is presented with the background necessary to conduct pulsed NQR experiments. The {sup 14}N NQR energy levels and possible transitions are derived in step-by-step detail. The components of a pulsed NQR spectrometer are discussed along with the experimental techniques for conducting radiation effects experiments using the spectrometer. Three data analysis techniques -- the power spectral density Fourier transform, state space singular value decomposition (HSVD), and nonlinear curve fitting (using the downhill simplex method of global optimization and the Levenberg-Marquart method) -- are explained. These three techniques are integrated into an analytical method which uses these numerical techniques in this order to determine the physical NQR parameters. Sample data sets of urea and guanidine sulfate data are used to demonstrate how these methods can be employed to analyze both simple and complex free induction decays. By determining baseline values for biologically significant organics, radiation effects on the NQR parameters can be studied to provide a link between current radiation dosimetry techniques and the biological effects of radiation.

  19. Influence of late radiation effects on the immunological parameters of aging. Final technical report, September 1977-August 1983

    SciTech Connect

    Makinodan, T.

    1983-01-01

    A series of tests of immunologic function were used in assessing the immune status of individuals who survived the atomic bombs in Japan in 1945. A-bomb survivors (n=189) residing in the US were recruited to participate in the study. Survivors exposed to varying low doses of radiation (S/sub +/ group) had healthier immune responses than those exposed to O rads (S/sub 0/ group). The difference was significant for natural cytotoxicity (p = .028). Less striking differences with the same trend (i.e., S/sub +/ healthier than S/sub 0/) were observed with: the mixed lymphocyte reactions, mitogenic response to PHA, interferon production, serum interferon levels (all S/sub +/ > S/sub 0/), frequency of detectable immune complexes, rheumatoid factor, and antimitochondrial antibodies (all S/sub +/ > S/sub 0/). In order to study the Japanese A-bomb survivors, a collaborative study was initiated with the Radiation Research Effects Foundation in Hiroshima, Japan. Immunologic tests were performed on blood samples from 278 individuals including 202 survivors of whom approximately one-third each were exposed to 0, 1-99, and 100+ rads at the time of the bomb. A decrease in immune responses was observed with increasing exposure. It is interesting that, consistent with our findings on the American survivors, the Japanese survivors exposed to 1-9 rads showed a small increase in natural cytotoxicity compared to the group exposed to 0 rads. Females showed a stronger dose-related decline than males (who may have shown a slight increase) with natural cytotoxicity, and both groups showed a small effect with interleukin 2 production. With both tests males were higher than females. Natural cytotoxicity increased significantly with age, as did serum immune complex levels. In the pilot study of the murine model for plasmacytoma formation, it was shown that age and radiation may both predispose to plasmacytoma formation. 22 references, 5 tables.

  20. Modification on liquid retention property of cassava starch by radiation grafting with acrylonitrile. I. Effect of γ-irradiation on grafting parameters

    NASA Astrophysics Data System (ADS)

    Kiatkamjornwong, S.; Chvajarernpun, J.; Nakason, C.

    1993-07-01

    Radiation modification on liquid retention properties of native cassava starch, gelatinized at 85°C, by graft copolymerization with acrylonitrile was carried out by mutual irradiation to gamma-rays. A thin aluminum foil was used to cover the inner wall of the reaction vessel, so that the homopolymer concentration was reduced to be less than 1.0% with a distilled water retention value of 665 g/g of the dry weight of the saponified grafted product. Confirmation of graft copolymerization and saponification reactions was made by the infrared spectrophotometric technique. The combined effect of radiation parameters in terms of an irradiation time and a dose rate to the total dose on the extent of the grafting reaction expressed in terms of grafting parameters which directly influenced liquid retention values was evaluated in conjunction with statistical analysis.

  1. Analysis of radiation parameters to control the effects of Nd:YAG laser surgery on gastric malignancies

    NASA Astrophysics Data System (ADS)

    Pelayo-Fernández, M. L.; Fanjul-Vélez, F.; Salas-García, I.; Hernández-González, A.; Arce-Diego, J. L.

    2015-07-01

    Endoscopic laser surgery provides an advantageous alternative to Argon Plasma Coagulation, endoscopic tweezers or electro-ablation in gastroenterology that facilitates a selective ablation of stomach tumors with an additional hemostatic effect in the surrounding tissue. This coagulation effect can also be employed for the treatment of gastric ulcers. It is mandatory to control the laser parameters regardless of the desired effect, either cancerous tissue ablation or coagulation to prevent ulcerous bleeding, in order to avoid stomach wall perforation or an insufficient therapeutic outcome. Dosimetric models constitute an attractive tool to determine the proper light dose in order to offer a customized therapy planning that optimizes the treatment results. In this work, a model for Nd:YAG laser surgery is applied to predict both the coagulation zone in gastric ulcers and the removal in adenocarcinomas under different laser setups. Results show clear differences in the effective zone of the gastric malignancy affected by both coagulation and ablation. Therefore the current model could be employed in the clinical practice to plan the optimal laser beam parameters to treat a certain type of pathologic stomach tissue with variable morphology and without risk of perforation or undertreated parts.

  2. Gamma radiation effects on physico-chemical parameters of apple fruit during commercial post-harvest preservation

    NASA Astrophysics Data System (ADS)

    Mostafavi, Hossein Ahari; Mirmajlessi, Seyed Mahyar; Mirjalili, Seyed Mohammad; Fathollahi, Hadi; Askari, Hadi

    2012-06-01

    The physico-chemical parameters (including moisture, total soluble solids, antioxidant activity, phenolic content and firmness) of cv. Red Delicious apple subjected to γ radiation were evaluated for their ability to avoid the post-harvest blue mold caused by Penicillium expansum during cold storage. Freshly harvested apples were inoculated with P. expansum. Treated fruits were irradiated at doses of 0, 300, 600, 900 and 1200 Gy and stored at 1 °C. Apples were evaluated at three month intervals. The results showed that there was a clear link between phenolic content and antioxidant activity, so that dose range of 900 Gy and higher significantly decreased phenolic content and antioxidant activity. The moisture percent of stored apples was more responsive to irradiation (at doses of 900-1200 Gy) than storage time and pathogen. Lesion diameter of pathogen-treated non-irradiated apples was significantly increased after three months. This means that storage at low temperature is not enough to avoid blue mold growth. As dose and storage time increased firmness decreased; also pathogen accelerated softening of stored apples. This study showed conclusively that low irradiation doses (300 and 600 Gy) combined with cold storage is a way to minimize apple quality losses during nine month storage period.

  3. Effect of Left Versus Right Radial Artery Approach for Coronary Angiography on Radiation Parameters in Patients With Predictors of Transradial Access Failure.

    PubMed

    Shah, Binita; Burdowski, Joseph; Guo, Yu; Velez de Villa, Bryan; Huynh, Andrew; Farid, Meena; Maini, Mansi; Serrano-Gomez, Claudia; Staniloae, Cezar; Feit, Frederick; Attubato, Michael J; Slater, James; Coppola, John

    2016-08-15

    Left transradial approach (TRA) for coronary angiography is associated with lower radiation parameters than right TRA in an all-comers population. The aim of this study was to determine the effects of left versus right TRA on radiation parameters in patients with predictors of TRA failure. Patients with predictors of TRA failure (≥3 of 4 following criteria: age ≥70 years, female gender, height ≤64 inches, and hypertension) referred to TRA operators were randomized to either right (n = 50) or left (n = 50) TRA, whereas those referred to transfemoral approach (TFA) operators were enrolled in a prospective registry (n = 50). The primary end point was the radiation measure of dose-area product (DAP). In an intention-to-treat analysis, DAP (34.1 Gy·cm(2) [24.9 to 45.6] vs 41.9 Gy·cm(2) [27.3 to 58.0], p = 0.08), fluoroscopy time (3.7 minutes [2.4 to 6.3] vs 5.6 minutes [3.1 to 8.7], p = 0.07), and operator radiation exposure (516 μR [275 to 967] vs 730 μR [503 to 1,165], p = 0.06) were not significantly different between left and right TRA, but total dose (411 mGy [310 to 592] vs 537 mGy [368 to 780], p = 0.03) was significantly lower with left versus right TRA. Radiation parameters were lowest in the TFA cohort (DAP 24.5 Gy·cm(2) [15.7 to 33.2], p <0.001; fluoroscopy time 2.3 minutes [1.5 to 3.7], p <0.001; operator radiation exposure 387 μR [264 to 557]; total dose 345 mGy [250 to 468], p = 0.001). Results were similar after adjustment for differences in baseline characteristics. In conclusion, median measurements of radiation were overall not significantly different between left versus right TRA in this select population of patients with predictors of TRA failure. All measurements of radiation were lowest in the TFA group. PMID:27328954

  4. Integrated effect of gamma radiation and biocontrol agent on quality parameters of apple fruit: An innovative commercial preservation method

    NASA Astrophysics Data System (ADS)

    Ahari Mostafavi, Hossein; Mahyar Mirmajlessi, Seyed; Fathollahi, Hadi; Shahbazi, Samira; Mohammad Mirjalili, Seyed

    2013-10-01

    Effects of gamma irradiation and biocontrol agent (Pseudomonas fluorescens) on the physico-chemical parameters (including moisture, total soluble solids, antioxidant activity, phenolic content and firmness) of cv. Golden Delicious apples were investigated for their ability to avoid the post-harvest blue mold caused by Penicillium expansum during cold storage. Freshly harvested apples were inoculated with P. expansum. Treated fruits were irradiated at doses of 0, 200, 400, 600 and 800 Gy and then inoculated with P. fluorescens suspension. Samples were evaluated at 3 month intervals. The results demonstrated a clear link between antioxidant activity and phenolic content, so that dose range of 200-400 Gy significantly increased phenolic content and antioxidant activity. Effect of P. fluorescens was similar to irradiation at 200 and 400 Gy that could prevent lesion diameter in pathogen-treated apples. As dose and storage time increased firmness decreased but, combination of P. fluorescens as well as irradiation (at 200-400 Gy) could decrease softening apple fruits during storage. In all parameters, P. fluorescens (as biocontrol agent) inhibited P. expansum similar to irradiation at 200-400 Gy. So, integrated treatment of irradiation and biocontrol agent explored the potential dual benefit of low doses (200 and 400 Gy) as a suitable method to sustain physico-chemical quality and conclusively reduce apple fruits losses during post-harvest preservation.

  5. The effects of UV-B radiation intensity on biochemical parameters and active ingredients in flowers of Qi chrysanthemum and Huai chrysanthemum.

    PubMed

    Yao, Xiao-Qin; Chu, Jian-Zhou; He, Xue-Li; Si, Chao

    2014-01-01

    The article studied UV-B effects on biochemical parameters and active ingredients in flowers of Qi chrysanthemum and Huai chrysanthemum during the bud stage. The experiment included four UV-B radiation levels (CK, ambient UV-B; T1, T2 and T3 indicated a 5%, 10% and 15% increase in ambient UV-BBE, respectively) to determine the optimal UV-B radiation intensity in regulating active ingredients level in flowers of two chrysanthemum varieties. Flower dry weight of two cultivars was not affected by UV-B radiation under experimental conditions reported here. UV-B treatments significantly increased the rate of superoxide radical production, hydrogen peroxide (H2O2) (except for T1) and malondialdehyde concentration in flowers of Huai chrysanthemum and H2O2 concentration in flowers of Qi chrysanthemum. T2 and T3 treatments induced a significant increase in phenylalanine ammonia lyase enzyme (PAL) activity, anthocyanins, proline, ascorbic acid, chlorogenic acid and flavone content in flowers of two chrysanthemum varieties, and there were no significant differences in PAL activity, ascorbic acid, flavone and chlorogenic acid content between the two treatments. These results indicated that appropriate UV-B radiation intensity did not result in the decrease in flower yield, and could regulate PAL activity and increase active ingredients content in flowers of two chrysanthemum varieties. PMID:25112378

  6. The effect of high energy (HZE) particle radiation (Ar-40) on aging parameters of mouse hippocampus and retina

    NASA Technical Reports Server (NTRS)

    Philpott, D. E.; Kato, K.; Corbett, R.; Stevenson, J.; Black, S.; Sapp, W.; Miquel, J.; Lindseth, K. A.; Benton, E. V.

    1985-01-01

    Eight month old C57BL6 mice were exposed (head only) to 0.5 rad or 50 rads of Argon particles at the Lawrence Berkeley Radiation Facility, CA. Neuromotor performance was assessed monthly for six months beginning twelve weeks post-irradiation using a 'string test'. The decline in motor performance was dose-related and none of the animals was able to complete the task after four months of testing. Morphological changes were monitored six and twelve months post-irradiation by light and electron microscopy. The synaptic density in the CA-1 area of the hippocampus decreased six and twelve months after irradiation. The decrease after twelve months was less than after six months. The width of the outer nuclear layer (ONL) of the retina increased with increasing dose. The number of blood vessels between the ONL and the ganglion layer decreased twelve months after irradiation and this area did not show significant accumulation of age pigment.

  7. Effect of high energy (HZE) particle radiation (40Ar) on aging parameters of mouse hippocampus and retina

    SciTech Connect

    Philpott, D.E.; Sapp, W.; Miquel, J.; Kato, K.; Corbett, R.; Stevenson, J.; Black, S.; Lindseth, K.A.; Benton, E.V.

    1985-01-01

    Eight month old C57BL6 mice were exposed (head only) to 0.5 rad or 50 rads of Argon particles at the Lawrence Berkeley Radiation Facility, CA. Neuromotor performance was assessed monthly for six months beginning twelve weeks post-irradiation using a string test. The decline in motor performance was dose-related and none of the animals was able to complete the task after four months of testing. Morphological changes were monitored six and twelve months post-irradiation by light and electron microscopy. The synaptic density in the CA-1 area of the hippocampus decreased six and twelve months after irradiation. The decrease after twelve months was less than after six months. The width of the outer nuclear layer (ONL) of the retina increased with increasing dose. The number of blood vessels between the ONL and the ganglion layer decreased twelve months after irradiation and this area did not show significant accumulation of age pigment.

  8. Radiation effects in space

    SciTech Connect

    Fry, R.J.M.

    1986-01-01

    The paper discusses the radiation environment in space that astronauts are likely to be exposed to. Emphasis is on proton and HZE particle effects. Recommendations for radiation protection guidelines are presented. (ACR)

  9. Kinetic parameters of uracil dosimeter in simulated extraterrestrial UV radiation

    NASA Astrophysics Data System (ADS)

    Kovács, G.; Gróf, P.; Bérces, A.; Patel, M. R.; Lammer, H.; Rontó, Gy.

    Studies of the solar UV environment on Earth 2.0 Gyr to 3.8 Gyr ago suggest that the terrestrial atmosphere was essentially anoxic, resulting in an ozone column abundance insufficient for protecting the planetary surface in the UV-B (280 nm - 315 nm) and the UV-C (200 nm - 280 nm) ranges. Since, short wavelength solar UV radiation in the UV-B and UV-C range penetrated through the atmosphere to the unprotected early Earth's surface, associated biological consequences may be expected. We discuss experimental data obtained as follows: Radiation sources applied were solar simulator and high power deuterium lamp, the wavelength were adjusted by interference filters (210, 230, 250 nm) and the irradiances were measured by OL754 spectroradiometer. The photo-reverse effect depends highly on the wavelength of the exposed radiation. Shorter wavelength UV radiation of about 200 nm is strongly effective in monomerization, while the longer wavelengths prefer the production of dimerization. In case of polychromatic light, like in space or on a planetary surface which is unprotected by an ozone layer the two processes run parallel. We could demonstrate experimentally, for the case of a uracil thin-layer that the photo-reaction process of the nucleotides can be both dimerization and the reverse process: monomerization. These results are important for the study of solar UV effects on organisms in the early terrestrial environment as well as for the search for life on Mars since we can show that biological harmful effects can also be reduced by shorter wavelength UV radiation, which is of importance in reducing DNA damages provoked by wavelengths longer than about 240 nm. Our earlier results showed that dimerization of the pyrimidin base uracil can be described by a first order kinetics, and this reaction gives the possibility to determine the dose of the UV source applied. This work is a theoretical and experimental approach to the relevant parameters of the first order kinetics.

  10. Gravitational Stokes parameters. [for electromagnetic and gravitational radiation in relativity

    NASA Technical Reports Server (NTRS)

    Anile, A. M.; Breuer, R. A.

    1974-01-01

    The electromagnetic and gravitational Stokes parameters are defined in the general theory of relativity. The general-relativistic equation of radiative transfer for polarized radiation is then derived in terms of the Stokes parameters for both high-frequency electromagnetic and gravitational waves. The concept of Stokes parameters is generalized for the most general class of metric theories of gravity, where six (instead of two) independent states of polarization are present.

  11. Radiation effects in space

    SciTech Connect

    Fry, R.J.M.

    1987-07-01

    As more people spend more time in space, and the return to the moon and exploratory missions are considered, the risks require continuing examination. The effects of microgravity and radiation are two potential risks in space. These risks increase with increasing mission duration. This document considers the risk of radiation effects in space workers and explorers. 17 refs., 1 fig., 4 tabs.

  12. Microcircuit radiation effects databank

    NASA Technical Reports Server (NTRS)

    1983-01-01

    Radiation test data submitted by many testers is collated to serve as a reference for engineers who are concerned with and have some knowledge of the effects of the natural radiation environment on microcircuits. Total dose damage information and single event upset cross sections, i.e., the probability of a soft error (bit flip) or of a hard error (latchup) are presented.

  13. Radiation: Doses, Effects, Risks.

    ERIC Educational Resources Information Center

    Lean, Geoffrey, Ed.

    Few scientific issues arouse as much public controversy as the effects of radiation. This booklet is an attempt to summarize what is known about radiation and provide a basis for further discussion and debate. The first four chapters of the booklet are based on the most recent reports to the United Nations' General Assembly by the United Nations…

  14. [Genetic effects of radiation].

    PubMed

    Nakamura, Nori

    2012-03-01

    This paper is a short review of genetic effect of radiation. This includes methods and results of a large-scale genetic study on specific loci in mice and of various studies in the offspring of atomic-bomb survivors. As for the latter, there is no results obtained which suggest the effect of parental exposure to radiation. Further, in recent years, studies are conducted to the offspring born to parents who were survivors of childhood cancers. In several reports, the mean gonad dose is quite large whereas in most instances, the results do not indicate genetic effect following parental exposure to radiation. Possible reasons for the difficulties in detecting genetic effect of radiation are discussed. PMID:22514926

  15. Radiation Effects In Space

    SciTech Connect

    Tripathi, Ram K.

    2011-06-01

    Protecting space missions from severe exposures from radiation, in general, and long duration/deep space human missions, in particular, is a critical design driver, and could be a limiting factor. The space radiation environment consists of galactic cosmic rays (GCR), solar particle events (SPE), trapped radiation, and includes ions of all the known elements over a very broad energy range. These ions penetrate spacecraft materials producing nuclear fragments and secondary particles that damage biological tissues and microelectronic devices. One is required to know how every element (and all isotopes of each element) in the periodic table interacts and fragments on every other element in the same table as a function of kinetic energy ranging over many decades. In addition, the accuracy of the input information and database, in general and nuclear data in particular, impacts radiation exposure health assessments and payload penalty. After a brief review of effects of space radiation on materials and electronics, human space missions to Mars is discussed.

  16. Radiation effects in space

    NASA Astrophysics Data System (ADS)

    Fry, R. J. M.

    The radiation protection guidelines of the National Aeronautics and Space Administration (NASA) are under review by Scientific Committe 75 of the National Council on Radiation Protection and Measurements. The re-evaluation of the current guidelines is necessary, first, because of the increase in information about radiation risks since 1970 when the original recommendations were made and second, the population at risk has changed. For example, women have joined the ranks of the astronauts. Two types of radiation, protons and heavy ions, are of particular concern in space. Unfortunately, there is less information about the effects on tissues and the induction of cancer by these radiations than by other radiations. The choice of Quality Factors (Q) for obtaining dose equivalents for these radiations, is an important aspect of the risk estimate for space travel. There are not sufficient data for the induction of late effects by either protons or by heavy ions. The current information suggests a RBE for the relative protons of about 1, whereas, -a RBE of 20 for tumor induction by heavy ions, such as iron-56, appears appropriate. The recommendations for the dose equivalent career limits for skin and the lens of the eye have been reduced but the 30-day and annual limits have been raised.

  17. Microcircuit radiation effects databank

    NASA Technical Reports Server (NTRS)

    1983-01-01

    This databank is the collation of radiation test data submitted by many testers and serves as a reference for engineers who are concerned with and have some knowledge of the effects of the natural radiation environment on microcircuits. It contains radiation sensitivity results from ground tests and is divided into two sections. Section A lists total dose damage information, and section B lists single event upset cross sections, I.E., the probability of a soft error (bit flip) or of a hard error (latchup).

  18. Radiation effects in space.

    PubMed

    Fry, R J

    1986-01-01

    The radiation protection guidelines of the National Aeronautics and Space Administration (NASA) are under review by Scientific Committee 75 of the National Council Protection and Measurements. The re-evaluation of the current guidelines is necessary, first, because of the increase in information about radiation risks since 1970 when the original recommendations were made and second, the population at risk has changed. For example, women have joined the ranks of the astronauts. Two types of radiation, protons and heavy ions, are of particular concern in space. Unfortunately, there is less information about the effects on tissues and cancer by these radiations than by other radiations. The choice of Quality Factors (Q) for obtaining dose equivalents for these radiations, is an important aspect of the risk estimate for space travel. There are not sufficient data for the induction of late effects by either protons or by heavy ions. The current information suggests a RBE for the relative protons of about 1, whereas, a RBE of 20 for tumor induction by heavy ions, such as iron-56, appears appropriate. The recommendations for the dose equivalent career limits for skin and the lens of the eye have been reduced but the 30-day and annual limits have been raised. PMID:11537230

  19. Analysis of the selected optical parameters of filters protecting against hazardous infrared radiation

    PubMed Central

    Gralewicz, Grzegorz; Owczarek, Grzegorz

    2016-01-01

    The paper analyses the selected optical parameters of protective optic filters used for protection of the eyes against hazardous radiation within the visible (VIS) and near infrared (NIR) spectrum range. The indexes characterizing transmission and reflection of optic radiation incident on the filter are compared. As it follows from the completed analysis, the newly developed interference filters provide more effective blocking of infrared radiation in comparison with the currently used protective filters. PMID:26327153

  20. Analysis of the selected optical parameters of filters protecting against hazardous infrared radiation.

    PubMed

    Gralewicz, Grzegorz; Owczarek, Grzegorz

    2016-09-01

    The paper analyses the selected optical parameters of protective optic filters used for protection of the eyes against hazardous radiation within the visible (VIS) and near infrared (NIR) spectrum range. The indexes characterizing transmission and reflection of optic radiation incident on the filter are compared. As it follows from the completed analysis, the newly developed interference filters provide more effective blocking of infrared radiation in comparison with the currently used protective filters. PMID:26327153

  1. Biological Effects of Ionizing Radiation

    DOE R&D Accomplishments Database

    Ingram, M.; Mason, W. B.; Whipple, G. H.; Howland, J. W.

    1952-04-07

    This report presents a review of present knowledge and concepts of the biological effects of ionizing radiations. Among the topics discussed are the physical and chemical effects of ionizing radiation on biological systems, morphological and physiological changes observed in biological systems subjected to ionizing radiations, physiological changes in the intact animal, latent changes following exposure of biological systems to ionizing radiations, factors influencing the biological response to ionizing radiation, relative effects of various ionizing radiations, and biological dosimetry.

  2. Semi-empirical determination of radiative parameters for Ag II

    NASA Astrophysics Data System (ADS)

    Ruczkowski, J.; Elantkowska, M.; Dembczyński, J.

    2016-07-01

    The aim of this paper is to determine the values of radiative parameters for Ag II by means of a semi-empirical method. The calculated values of oscillator strengths and lifetimes are, in majority of cases, in a very good agreement with accurate experimental data. Our calculation procedures allowed us to obtain the values of transition integrals and predict the values of oscillator strengths for the transitions in a wide spectral range and radiative lifetimes for excited levels. Moreover, the predicted values will be useful when the experimental values are not known.

  3. Measurement of parameters in Indus-2 synchrotron radiation source

    SciTech Connect

    Ghodke, A. D.; Husain, Riyasat; Kumar, Pradeep; Yadav, Surendra; Puntambekar, T. A.

    2012-10-15

    The paper presents the measurement of optics parameters in Indus-2 synchrotron radiation source, which include betatron tune, beta function, dispersion function, natural chromaticity, corrected chromaticity, central RF frequency, momentum compaction factor, and linear betatron coupling. Two methods were used for beta function measurement; a conventional quadrupole scan method and a method using the fitting of the orbit response matrix. A robust Levenberg-Marquardt algorithm was used for nonlinear least square fitting of the orbit response matrix. In this paper, detailed methods for the parameter measurements are described. The measured results are discussed and compared with the theoretical values obtained using accelerator simulation code Accelerator Toolbox in MATLAB.

  4. Effects of radiation on carbapenems

    NASA Astrophysics Data System (ADS)

    Tepe, Semra; Polat, Mustafa; Korkmaz, Mustafa

    In the present work, effects of gamma radiation on solid meropenem trihydrate (MPT), which is the active ingredient of carbapenem antibiotics, were investigated by electron spin resonance (ESR) spectroscopy. Irradiated MPT presents an ESR spectrum consisting of many resonance peaks. Heights measured with respect to the spectrum baseline of these resonance peaks were used to explore the evolutions of the radicalic species responsible for the experimental spectrum under different conditions. Variations of the denoted 11 peak heights with microwave power, sample temperature and applied radiation doses and decay of the involved radicalic species at room and at high temperatures were studied. On the basis of the results derived from these studies, a molecular model consisting of the presence of four different radicalic species was proposed, and spectroscopic parameters of these species were calculated through spectrum simulation calculations. The dosimetric potential of MPT was also explored and it was concluded that MPT presents the characteristics of normal and accidental dosimetric materials.

  5. The evaluation of radiation damage parameter for CVD diamond

    NASA Astrophysics Data System (ADS)

    Grilj, V.; Skukan, N.; Jakšić, M.; Pomorski, M.; Kada, W.; Kamiya, T.; Ohshima, T.

    2016-04-01

    There are a few different phenomenological approaches that aim to track the dependence of signal height in irradiated solid state detectors on the fluence of damaging particles. However, none of them are capable to provide a unique radiation hardness parameter that would reflect solely the material capability to withstand high radiation environment. To extract such a parameter for chemical vapor deposited (CVD) diamond, two different diamond detectors were irradiated with proton beams in MeV energy range and subjected afterwards to ion beam induced charge (IBIC) analysis. The change in charge collection efficiency (CCE) due to defects produced was investigated in context of a theoretical model that was developed on the basis of the adjoint method for linearization of the continuity equations of electrons and holes. Detailed modeling of measured data resulted with the first known value of the kσ product for diamond, where k represents the number of charge carriers' traps created per one simulated primary lattice vacancy and σ represents the charge carriers' capture cross section. As discussed in the text, this product could be considered as a true radiation damage parameter.

  6. Thorium-232 in human tissues: Metabolic parameters and radiation doses

    SciTech Connect

    Stehney, A.F.

    1994-09-01

    Higher than environmental levels of {sup 232}Th have been found in autopsy samples of lungs and other organs from four former employees of a Th refinery. Working periods of the subjects ranged from 3 to 24 years, and times from end of work to death ranged from 6 to 31 years. Concentrations of {sup 232}Th in these samples and in tissues from two cases of non-occupational exposure were examined for compatibility with dosimetric models in Publication 30 of the International Commission on Radiological Protection (ICPP 1979a). The concentrations of {sup 232}Th in the lungs of the Th workers relative to the concentrations in bone or liver were much higher than calculated from the model for class Y aerosols of Th and the exposure histories of the subjects, and concentrations in the pulmonary lymph nodes were much lower than calculated for three of the Th workers and both non-occupational cases. Least-squares fits to the measured concentrations showed that the biological half-times of Th in liver, spleen, and kidneys are similar to the half-time in bone instead of the factor of 10 less suggested in Publication 30, and the fractions translocated from body fluids were found to be about 0.03, 0.02, and 0.005, respectively, when the fraction to bone was held at the suggested value of 0.7. Fitted values of the respiratory parameters differed significantly between cases and the differences were ascribable to aerosol differences. Average inhalation rates calculated for individual Th workers ranged from 50 to 110 Bq {sup 232}Th y{sup {minus}1}, and dose equivalents as high as 9.3 Sv to the lungs, 2.0 Sv to bone surfaces, and 1.1 Sv effective dose equivalent were calculated from the inhalation rates and fitted values of the metabolic parameters. The radiation doses were about the same when calculated from parameter values fitted with an assumed translocation fraction of 0.2 from body fluids to bone instead of 0.7.

  7. Radiation Effects: Core Project

    NASA Technical Reports Server (NTRS)

    Dicello, John F.

    1999-01-01

    The risks to personnel in space from the naturally occurring radiations are generally considered to be one of the most serious limitations to human space missions, as noted in two recent reports of the National Research Council/National Academy of Sciences. The Core Project of the Radiation Effects Team for the National Space Biomedical Research Institute is the consequences of radiations in space in order to develop countermeasure, both physical and pharmaceutical, to reduce the risks of cancer and other diseases associated with such exposures. During interplanetary missions, personnel in space will be exposed to galactic cosmic rays, including high-energy protons and energetic ions with atomic masses of iron or higher. In addition, solar events will produce radiation fields of high intensity for short but irregular durations. The level of intensity of these radiations is considerably higher than that on Earth's surface, and the biological risks to astronauts is consequently increased, including increased risks of carcinogenesis and other diseases. This group is examining the risk of cancers resulting from low-dose, low-dose rate exposures of model systems to photons, protons, and iron by using ground-based accelerators which are capable of producing beams of protons, iron, and other heavy ions at energies comparable to those encountered in space. They have begun the first series of experiments using a 1-GeV iron beam at the Brookhaven National Laboratory and 250-MeV protons at Loma Linda University Medical Center's proton synchrotron facility. As part of these studies, this group will be investigating the potential for the pharmaceutical, Tamoxifen, to reduce the risk of breast cancer in astronauts exposed to the level of doses and particle types expected in space. Theoretical studies are being carried out in a collaboration between scientists at NASA's Johnson Space Center and Johns Hopkins University in parallel with the experimental program have provided

  8. Ionization Parameter: A Diagnostic of Radiation Pressure Dominated HII Regions

    NASA Astrophysics Data System (ADS)

    Yeh, Sherry; Matzner, C. D.

    2011-01-01

    When irradiation is sufficiently intense, the structure of an HII region will be dominated by radiation pressure and stellar winds, rather than ionized gas pressure. This state is of considerable interest because of its role in the formation of massive stars, the disruption of giant molecular clouds, and the evolution of starburst galaxies. We discuss the usefulness of the ionization parameter U, as often derived from observed line ratios between species which exist only in ionized gas, as a diagnostic for the radiation pressure-dominated state. In ionization-bounded directions, U cannot exceed a maximum value Umax determined by equilibrium between radiation and gas pressure forces. Lower values of U will occur, however, when the pressure of shocked stellar winds is significant, or when neutral gas is broken into clumps with sufficiently small radii of curvature. Applying these considerations to a prominent ionized shell around 30 Doradus and to the inner starburst region of M82, along with Cloudy simulations, we conclude that both are dominated by a combination of radiation pressure and shocked winds.

  9. On equilibrium parameters of a radiation-compression model pinch

    SciTech Connect

    Afonin, V.I.

    1994-12-31

    Up to date, the micropinch effect in high-current axially symmetric electric discharges was the subject of extensive theoretical and experimental research. The radiation compression mechanism proved to fit the experimental data better than any other model. It assumes the pinch equilibrium to occur when the surface radiation emission replaces the surface emission mode. The aim of the present work is to show that a quasi-stationary pinch state can exist in the case of an optically thin plasma as well. 8 figs.

  10. Precision Measurement of the Undulator K Parameter using Spontaneous Radiation

    SciTech Connect

    Welch, J.J.; Arthur, J.; Emma, P.; Hastings, J.B.; Huang, Z.; Nuhn, H.D.; Stefan, P.; Bionta, R.M.; Dejus, R.J.; Yang, B.X.; /Argonne

    2007-04-17

    Obtaining precise values of the undulator parameter, K, is critical for producing high-gain FEL radiation. At the LCLS [1], where the FEL wavelength reaches down to 1.5 {angstrom}, the relative precision of K must satisfy ({Delta}K/K){sub rms} {approx}< 0.015% over the full length of the undulator. Transverse misalignments, construction errors, radiation damage, and temperature variations all contribute to errors in the mean K values among the undulator segments. It is therefore important to develop some means to measure relative K values, after installation and alignment. We propose a method using the angle-integrated spontaneous radiation spectrum of two nearby undulator segments, and the natural shot-to-shot energy jitter of the electron beam. Simulation of this scheme is presented using both ideal and measured undulator fields. By ''leap-frogging'' to different pairs of segments with extended separations we hope to confirm or correct the values of K, including proper tapering, over the entire 130-m long LCLS undulator.

  11. Correlations between solar wind parameters and auroral kilometric radiation intensity

    NASA Technical Reports Server (NTRS)

    Gallagher, D. L.; Dangelo, N.

    1981-01-01

    The relationship between solar wind properties and the influx of energy into the nightside auroral region as indicated by the intensity of auroral kilometric radiation is investigated. Smoothed Hawkeye satellite observations of auroral radiation at 178, 100 and 56.2 kHz for days 160 through 365 of 1974 are compared with solar wind data from the composite Solar Wind Plasma Data Set, most of which was supplied by the IMP-8 spacecraft. Correlations are made between smoothed daily averages of solar wind ion density, bulk flow speed, total IMF strength, electric field, solar wind speed in the southward direction, solar wind speed multiplied by total IMF strength, the substorm parameter epsilon and the Kp index. The greatest correlation is found between solar wind bulk flow speed and auroral radiation intensity, with a linear correlation coefficient of 0.78 for the 203 daily averages examined. A possible mechanism for the relationship may be related to the propagation into the nightside magnetosphere of low-frequency long-wavelength electrostatic waves produced in the magnetosheath by the solar wind.

  12. Effects of dimerization on the photoelectron angular distribution parameters from chiral camphor enantiomers obtained with circularly polarized vacuum-ultraviolet radiation

    SciTech Connect

    Nahon, Laurent; Garcia, Gustavo A.; Soldi-Lose, Heloiese; Daly, Steven; Powis, Ivan

    2010-09-15

    As an intermediate state of matter between the free monomeric gas phase and the solid state, clusters may exhibit a specific electronic structure and photoionization dynamics that can be unraveled by different types of electron spectroscopies. From mass-selected ion yield scans measured for photoionization of (R)-camphor, the ionization potentials (IPs) of the monomer (8.66{+-}0.01 eV), and of the homochiral dimer ({<=}8.37{+-}0.01 eV) and trimer ({<=}8.30{+-}0.01 eV) were obtained. These spectra, combined with threshold photoelectron spectroscopy and velocity map ion imaging, allow us to show that the camphor monomer and dimer photoionization channels are decoupled, i.e., that the highest occupied molecular orbital (HOMO) of the dimer does not undergo a dissociative ionization process that would lead to a spurious contribution to the monomer ion channel. Therefore mass selection, as achieved in our imaging photoelectron-photoion coincidence experiments, leads to size selection of the nascent monomer or dimer species. Since both the monomer and dimer are chiral, their photoelectron angular distribution (PAD) not only involves the usual {beta} anisotropy parameter but also a chiral asymmetry parameter b{sub 1} that can generate a forward-backward asymmetry in the PAD. This has been investigated using circularly polarized light (CPL) to record the photoelectron circular dichroism (PECD) in the near-threshold vacuum-ultraviolet (VUV) photoionization region. Analysis of size-selected electron images recorded with left- and right-handed CPL shows that over the first 1.5 eV above the HOMO orbital ionization potentials (IPs), the {beta} parameter is not affected by the dimerization process, while the chiral b{sub 1} parameter shows clear differences between the monomer and the dimer, confirming that PECD is a subtle long-range probe of the molecular potential.

  13. Effects of dimerization on the photoelectron angular distribution parameters from chiral camphor enantiomers obtained with circularly polarized vacuum-ultraviolet radiation

    NASA Astrophysics Data System (ADS)

    Nahon, Laurent; Garcia, Gustavo A.; Soldi-Lose, Héloïse; Daly, Steven; Powis, Ivan

    2010-09-01

    As an intermediate state of matter between the free monomeric gas phase and the solid state, clusters may exhibit a specific electronic structure and photoionization dynamics that can be unraveled by different types of electron spectroscopies. From mass-selected ion yield scans measured for photoionization of (R)-camphor, the ionization potentials (IPs) of the monomer (8.66±0.01 eV), and of the homochiral dimer (⩽8.37±0.01 eV) and trimer (⩽8.30±0.01 eV) were obtained. These spectra, combined with threshold photoelectron spectroscopy and velocity map ion imaging, allow us to show that the camphor monomer and dimer photoionization channels are decoupled, i.e., that the highest occupied molecular orbital (HOMO) of the dimer does not undergo a dissociative ionization process that would lead to a spurious contribution to the monomer ion channel. Therefore mass selection, as achieved in our imaging photoelectron-photoion coincidence experiments, leads to size selection of the nascent monomer or dimer species. Since both the monomer and dimer are chiral, their photoelectron angular distribution (PAD) not only involves the usual β anisotropy parameter but also a chiral asymmetry parameter b1 that can generate a forward-backward asymmetry in the PAD. This has been investigated using circularly polarized light (CPL) to record the photoelectron circular dichroism (PECD) in the near-threshold vacuum-ultraviolet (VUV) photoionization region. Analysis of size-selected electron images recorded with left- and right-handed CPL shows that over the first 1.5 eV above the HOMO orbital ionization potentials (IPs), the β parameter is not affected by the dimerization process, while the chiral b1 parameter shows clear differences between the monomer and the dimer, confirming that PECD is a subtle long-range probe of the molecular potential.

  14. Nanoparticles for Radiation Therapy Enhancement: the Key Parameters

    PubMed Central

    Retif, Paul; Pinel, Sophie; Toussaint, Magali; Frochot, Céline; Chouikrat, Rima; Bastogne, Thierry; Barberi-Heyob, Muriel

    2015-01-01

    This review focuses on the radiosensitization strategies that use high-Z nanoparticles. It does not establish an exhaustive list of the works in this field but rather propose constructive criticisms pointing out critical factors that could improve the nano-radiation therapy. Whereas most reviews show the chemists and/or biologists points of view, the present analysis is also seen through the prism of the medical physicist. In particular, we described and evaluated the influence of X-rays energy spectra using a numerical analysis. We observed a lack of standardization in preclinical studies that could partially explain the low number of translation to clinical applications for this innovative therapeutic strategy. Pointing out the critical parameters of high-Z nanoparticles radiosensitization, this review is expected to contribute to a larger preclinical and clinical development. PMID:26155318

  15. Nonlinearity of radiation health effects.

    PubMed Central

    Pollycove, M

    1998-01-01

    The prime concern of radiation protection policy since 1959 has been to protect DNA from damage. In 1994 the United Nations Scientific Community on the Effects of Atomic Radiation focused on biosystem response to radiation with its report Adaptive Responses to Radiation of Cells and Organisms. The 1995 National Council on Radiation Protection and Measurements report Principles and Application of Collective Dose in Radiation Protection states that because no human data provides direct support for the linear nonthreshold hypothesis (LNT), confidence in LNT is based on the biophysical concept that the passage of a single charged particle could cause damage to DNA that would result in cancer. Several statistically significant epidemiologic studies contradict the validity of this concept by showing risk decrements, i.e., hormesis, of cancer mortality and mortality from all causes in populations exposed to low-dose radiation. Unrepaired low-dose radiation damage to DNA is negligible compared to metabolic damage. The DNA damage-control biosystem is physiologically operative on both metabolic and radiation damage and effected predominantly by free radicals. The DNA damage-control biosystem is suppressed by high dose and stimulated by low-dose radiation. The hormetic effect of low-dose radiation may be explained by its increase of biosystem efficiency. Improved DNA damage control reduces persistent mis- or unrepaired DNA damage i.e., the number of mutations that accumulate during a lifetime. This progressive accumulation of gene mutations in stem cells is associated with decreasing DNA damage control, aging, and malignancy. Recognition of the positive health effects produced by adaptive responses to low-dose radiation would result in a realistic assessment of the environmental risk of radiation. Images Figure 1 Figure 3 Figure 5 Figure 6 Figure 8 Figure 10 PMID:9539031

  16. Effects of radiation on MEMS

    NASA Astrophysics Data System (ADS)

    Shea, Herbert R.

    2011-02-01

    The sensitivity of MEMS devices to radiation is reviewed, with an emphasis on radiation levels representative of space missions. While silicon and metals generally do not show mechanical degradation at the radiation levels encountered in most missions, MEMS devices have been reported to fail at doses of as few krad, corresponding to less than one year in most orbits. Radiation sensitivity is linked primarily to the impact on device operation of radiation-induced trapped charge in dielectrics, and thus affects most strongly MEMS devices operating on electrostatic principles. A survey of all published reports of radiation effects on MEMS is presented. The different sensing and actuation physical principles and materials used in MEMS are compared, leading to suggested was to increase radiation tolerance by design, for instance by choice of actuation principle or by electrical shielding of dielectrics.

  17. Spectroscopic characterization of the effect of gamma radiation on the physical parameters of biosynthesized silver/chitosan nano-particles and their antimicrobial activity

    NASA Astrophysics Data System (ADS)

    Osman, Mohamed E.; Eid, May M.; Khattab, Om kolthoum H.; El-Hallouty, Salwa M.; El-Marakby, Seham M.; Mahmoud, Doaa A.

    2015-09-01

    Studying the effect of pH on the biosynthesis of silver/chitosan nanoparticles (Ag/CS NPs) using Aspergillus deflectus and Penicillium pinophilum as reducing agents, showed very weak surface plasmon resonance (SPR) of Ag/CS NPs at certain pH. In this paper, the effect of irradiation on the synthesis of Ag/CS at non-optimum pH was evaluated and thereby, the antimicrobial effect of the biosynthesized Ag/CS NPs. The SPR of the AgNPs was analyzed by UV-visible spectroscopy. The active groups responsible for the reduction and capping of the AgNPs were analyzed by Fourier transform infrared (FTIR), and their shape and size were determined via high resolution transmission electron microscopy (HRTEM) and the dynamic light scattering (DLS) technique. UV/Visible spectroscopy confirmed the appearance of AgNPs’ SPR. Additionally, the FTIR spectroscopy confirmed the Ag/CS NP formation. Data also revealed that increasing both the pH and irradiation dose resulted in a decrease of the Ag/CS NPs’ size. DLS and HRTEM results showed that the best pH for biosynthesis of Ag/Cs is 7.5 at 50 kGy considering the particle size and crystallinity. Also, pH 8.5 gave the best antimicrobial activity of the Ag/CS NPs from Penicillium against both S. aureus and E. coli, while 8.5 and 7.5 were the best in the same order, for Ag/CS from Aspergillus.

  18. Physical Parameters of Hot Horizontal-Branch Stars in NGC 6752: Deep Mixing and Radiative Levitation

    NASA Technical Reports Server (NTRS)

    Moehler, S.; Sweigart, A. V.; Landsman, W. B.; Heber, U.; Catelan, M.

    1999-01-01

    Atmospheric parameters (T(sub eff), log g and log n(sub He)/n(sub H-dot)) are derived for 42 hot horizontal branch (HB) stars in the globular cluster NGC 6752. For 19 stars Mg II and Fe II lines are detected indicating an iron enrichment by a factor 50 on average with respect to the cluster abundance whereas the magnesium abundances are consistent with the cluster metallicity. This finding adds to the growing evidence that radiative levitation plays a significant role in determining the physical parameters of blue HB stars. Indeed, we find that iron enrichment can explain part, but not all, of the problem of anomalously low gravities along the blue HB. Thus the physical parameters of horizontal branch stars hotter than about 11,500 K in NGC 6752, as derived in this paper, are best explained by a combination of helium mixing and radiative levitation effects.

  19. Effective Material Parameter Retrieval for Terahertz Metamaterials

    NASA Astrophysics Data System (ADS)

    Kim, T.-T.; Choi, Muhan; Kim, Yushin; Min, Bumki

    Metamaterials, which are generally composed of subwavelength scale metallic structures, have been the subject of intensive research in recent years. Because their effective electromagnetic properties can be engineered by designing subwavelength scale metallic structures, called `meta-atoms', these artificially constructed materials are expected to lead to many new developments in the field of photonics. Furthermore, the terahertz (THz) frequency range has many important applications such as security detection, sensing, and biomedical imaging. Because many natural materials are inherently unresponsive to THz radiation, the natural materials that can be applied in devices in order to manipulate THz waves are very limited. Accordingly, the development of metamaterials with unusual optical properties in the THz frequency range has generated intense interest among researchers. In this part, design methods for metamaterials in the terahertz frequencies are introduced. This method is based on the unit cell design and S-parameter retrieval technique. Following a brief introduction to the method, some examples of terahertz metamaterial design will be presented in the last section.

  20. Radiation effects in nanoelectronic elements

    SciTech Connect

    Gromov, D. V.; Elesin, V. V.; Petrov, G. V.; Bobrinetskii, I. I.; Nevolin, V. K.

    2010-12-15

    Radiation defects induced in planar nanosized structures by steady and pulsed ionizing radiation have been analyzed. Characteristics of test samples with a planar nanosized structure fabricated by deposition of an ultrathin titanium film onto a semi-insulating GaAs substrate and of field-effect transistor structures based on bundles of carbon nanotubes have been studied. Physical mechanisms responsible for the radiation-induced changes in characteristics of the nanoelectronic elements under consideration have been established.

  1. Adaptive Multichannel Radiation Sensors for Plant Parameter Monitoring

    NASA Astrophysics Data System (ADS)

    Mollenhauer, Hannes; Remmler, Paul; Schuhmann, Gudrun; Lausch, Angela; Merbach, Ines; Assing, Martin; Mollenhauer, Olaf; Dietrich, Peter; Bumberger, Jan

    2016-04-01

    Nutrients such as nitrogen are playing a key role in the plant life cycle. They are much needed for chlorophyll production and other plant cell components. Therefore, the crop yield is strongly affected by plant nutrient status. Due to the spatial and temporal variability of soil characteristics or swaying agricultural inputs the plant development varies within a field. Thus, the determination of these fluctuations in the plant development is valuable for a detection of stress conditions and optimization of fertilisation due to its high environmental and economic impact. Plant parameters play crucial roles in plant growth estimation and prediction since they are used as indicators of plant performance. Especially indices derived out of remote sensing techniques provide quantitative information about agricultural crops instantaneously, and above all, non-destructively. Due to the specific absorption of certain plant pigments, a characteristic spectral signature can be seen in the visible and IR part of the electromagnetic spectrum, known as narrow-band peaks. In an analogous manner, the presence and concentration of different nutrients cause a characteristic spectral signature. To this end, an adequate remote sensing monitoring concept is needed, considering heterogeneity and dynamic of the plant population and economical aspects. This work will present the development and field investigations of an inexpensive multichannel radiation sensor to observe the incoming and reflected specific parts or rather distinct wavelengths of the solar light spectrum on the crop and facilitate the determination of different plant indices. Based on the selected sensor wavelengths, the sensing device allows the detection of specific parameters, e.g. plant vitality, chlorophyll content or nitrogen content. Besides the improvement of the sensor characteristic, the simple wavelength adaption, and the price-performance ratio, the achievement of appropriate energy efficiency as well as a

  2. Effects of Structural Errors on Parameter Estimates

    NASA Technical Reports Server (NTRS)

    Hadaegh, F. Y.; Bekey, G. A.

    1987-01-01

    Paper introduces concept of near equivalence in probability between different parameters or mathematical models of physical system. One in series of papers, each establishes different part of rigorous theory of mathematical modeling based on concepts of structural error, identifiability, and equivalence. This installment focuses upon effects of additive structural errors on degree of bias in estimates parameters.

  3. Radiation effects on structural materials

    SciTech Connect

    Ghoniem, N.M.

    1991-06-28

    This report discusses the following topics on the effect radiation has on thermonuclear reactor materials: Atomic Displacements; Microstructure Evolution; Materials Engineering, Mechanics, and Design; Research on Low-Activation Steels; and Research Motivated by Grant Support.

  4. Radiation Effects in Zircon

    SciTech Connect

    Ewing, Rodney C.; Meldrum, Alkiviathes; Wang, L. M.; Weber, William J.; Corrales, Louis R.

    2003-12-11

    The widespread distribution of zircon in the continental crust, its tendency to concentrate trace elements, particularly lanthanides and actinides, its use in age-dating, and its resistance to chemical and physical degradation have made zircon the most important accessory mineral in geologic studies. Because zircon is highly refractory, it also has important industrial applications, including its use as a lining material in high-temperature furnaces. However, during the past decade, zircon has also been proposed for advanced technology applications, such as a durable material for the immobilization of plutonium or, when modified by ion-beam irradiation, as an optic waveguide material. In all of these applications, the change in properties as a function of increasing radiation dose is of critical importance. In this chapter, we summarize the state-of-knowledge on the radiation damage accumulation process in zircon.

  5. Ultraviolet radiation effects

    NASA Technical Reports Server (NTRS)

    Slemp, Wayne S.

    1989-01-01

    Solar ultraviolet testing was not developed which will provide highly accelerated (20 to 50X) exposures that correlate to flight test data. Additional studies are required to develop an exposure methodology which will assure that accelerated testing can be used for qualification of materials and coatings for long duration space flight. Some conclusions are listed: Solar UV radiation is present in all orbital environments; Solar UV does not change in flux with orbital altitude; UV radiation can degrade most coatings and polymeric films; Laboratory UV simulation methodology is needed for accelerated testing to 20 UV solar constants; Simulation of extreme UV (below 200 nm) is needed to evaluate requirements for EUV in solar simulation.

  6. Radiation effects on corrosion of zirconium alloys

    SciTech Connect

    Johnson, A.B. Jr.

    1989-06-01

    From the wide use of zirconium alloys as components in nuclear reactors, has come clear evidence that reactor radiation is a major corrosion parameter. The evidence emerges from comparisons of zirconium alloy corrosion behavior in different reactor types, for example, BWRs versus PWRs and in corresponding reactor loop chemistries; also, oxidation rates differ with location along components such as fuel rods and reactor pressure tubes. In most respects, oxidation effects on power reactor components are paralleled by oxidation behavior on specimens exposed to radiation in reactor loops.

  7. Radiation-induced cardiovascular effects

    NASA Astrophysics Data System (ADS)

    Tapio, Soile

    Recent epidemiological studies indicate that exposure to ionising radiation enhances the risk of cardiovascular mortality and morbidity in a moderate but significant manner. Our goal is to identify molecular mechanisms involved in the pathogenesis of radiation-induced cardiovascular disease using cellular and mouse models. Two radiation targets are studied in detail: the vascular endothelium that plays a pivotal role in the regulation of cardiac function, and the myocardium, in particular damage to the cardiac mitochondria. Ionising radiation causes immediate and persistent alterations in several biological pathways in the endothelium in a dose- and dose-rate dependent manner. High acute and cumulative doses result in rapid, non-transient remodelling of the endothelial cytoskeleton, as well as increased lipid peroxidation and protein oxidation of the heart tissue, independent of whether exposure is local or total body. Proteomic and functional changes are observed in lipid metabolism, glycolysis, mitochondrial function (respiration, ROS production etc.), oxidative stress, cellular adhesion, and cellular structure. The transcriptional regulators Akt and PPAR alpha seem to play a central role in the radiation-response of the endothelium and myocardium, respectively. We have recently started co-operation with GSI in Darmstadt to study the effect of heavy ions on the endothelium. Our research will facilitate the identification of biomarkers associated with adverse cardiac effects of ionising radiation and may lead to the development of countermeasures against radiation-induced cardiac damage.

  8. The Dosimetric Effect of Intrafraction Prostate Motion on Step-and-Shoot Intensity-Modulated Radiation Therapy Plans: Magnitude, Correlation With Motion Parameters, and Comparison With Helical Tomotherapy Plans

    SciTech Connect

    Langen, Katja M.; Chauhan, Bhavin; Siebers, Jeffrey V.; Moore, Joseph; Kupelian, Patrick A.

    2012-12-01

    Purpose: To determine the daily and cumulative dosimetric effects of intrafraction prostate motion on step-and-shoot (SNS) intensity-modulated radiation therapy (IMRT) plans, to evaluate the correlation of dosimetric effect with motion-based metrics, and to compare on a fraction-by-fraction basis the dosimetric effect induced in SNS and helical tomotherapy plans. Methods and Materials: Intrafraction prostate motion data from 486 fractions and 15 patients were available. A motion-encoded dose calculation technique was used to determine the variation of the clinical target volume (CTV) D{sub 95%} values with respect to the static plan for SNS plans. The motion data were analyzed separately, and the correlation coefficients between various motion-based metrics and the dosimetric effect were determined. The dosimetric impact was compared with that incurred during another IMRT technique to assess correlation across different delivery techniques. Results: The mean ({+-}1 standard deviation [SD]) change in D{sub 95%} in the CTV over all 486 fractions was 0.2 {+-} 0.5%. After the delivery of five and 12 fractions, the mean ({+-}1 SD) changes over the 15 patients in CTV D{sub 95%} were 0.0 {+-} 0.2% and 0.1 {+-} 0.2%, respectively. The correlation coefficients between the CTV D{sub 95%} changes and the evaluated motion metrics were, in general, poor and ranged from r = -0.2 to r = -0.39. Dosimetric effects introduced by identical motion in SNS and helical tomotherapy IMRT techniques were poorly correlated with a correlation coefficient of r = 0.32 for the CTV. Conclusions: The dosimetric impact of intrafraction prostate motion on the CTV is, in general, small. In only 4% of all fractions did the dosimetric consequence exceed 1% in the CTV. As expected, the cumulative effect was further reduced with fractionation. The poor correlations between the calculated motion parameters and the subsequent dosimetric effect implies that motion-based thresholds are of limited value in

  9. INTERACTION BETWEEN METHYL MERCURY AND RADIATION EFFECTS ON NERVOUS SYSTEMS

    EPA Science Inventory

    The interaction between methyl mercury and ionizing radiation was investigated in a series of experiments using rats, hamsters, and squirrel monkeys to study the effects produced and possible mechanisms of action. Parameters evaluated included several measurements of behavior, br...

  10. Design considerations and test facilities for accelerated radiation effects testing

    NASA Technical Reports Server (NTRS)

    Price, W. E.; Miller, C. G.; Parker, R. H.

    1972-01-01

    Test design parameters for accelerated dose rate radiation effects tests for spacecraft parts and subsystems used in long term mission (years) are detailed. A facility for use in long term accelerated and unaccelerated testing is described.

  11. Space Radiation Effects Laboratory

    NASA Technical Reports Server (NTRS)

    1969-01-01

    The SREL User's Handbook is designed to provide information needed by those who plan experiments involving the accelerators at this laboratory. Thus the Handbook will contain information on the properties of the machines, the beam parameters, the facilities and services provided for experimenters, etc. This information will be brought up to date as new equipment is added and modifications accomplished. This Handbook is influenced by the many excellent models prepared at other accelerator laboratories. In particular, the CERN Synchrocyclotron User's Handbook (November 1967) is closely followed in some sections, since the SREL Synchrocyclotron is a duplicate of the CERN machine. We wish to thank Dr. E. G. Michaelis for permission to draw so heavily on his work, particularly in Section II of this Handbook. We hope that the Handbook will prove useful, and will welcome suggestions and criticism.

  12. Harmful effects of ultraviolet radiation

    SciTech Connect

    Not Available

    1989-07-21

    Tanning for cosmetic purposes by sunbathing or by using artificial tanning devices is widespread. The hazards associated with exposure to ultraviolet radiation are of concern to the medical profession. Depending on the amount and form of the radiation, as well as on the skin type of the individual exposed, ultraviolet radiation causes erythema, sunburn, photodamage (photoaging), photocarcinogenesis, damage to the eyes, alteration of the immune system of the skin, and chemical hypersensitivity. Skin cancers most commonly produced by ultraviolet radiation are basal and squamous cell carcinomas. There also is much circumstantial evidence that the increase in the incidence of cutaneous malignant melanoma during the past half century is related to increased sun exposure, but this has not been proved. Effective and cosmetically acceptable sunscreen preparations have been developed that can do much to prevent or reduce most harmful effects to ultraviolet radiation if they are applied properly and consistently. Other safety measures include (1) minimizing exposure to ultraviolet radiation, (2) being aware of reflective surfaces while in the sun, (3) wearing protective clothing, (4) avoiding use of artificial tanning devices, and (5) protecting infants and children.

  13. Radiation effects on human heredity.

    PubMed

    Nakamura, Nori; Suyama, Akihiko; Noda, Asao; Kodama, Yoshiaki

    2013-01-01

    In experimental organisms such as fruit flies and mice, increased frequencies in germ cell mutations have been detected following exposure to ionizing radiation. In contrast, there has been no clear evidence for radiation-induced germ cell mutations in humans that lead to birth defects, chromosome aberrations, Mendelian disorders, etc. This situation exists partly because no sensitive and practical genetic marker is available for human studies and also because the number of people exposed to large doses of radiation and subsequently having offspring was small until childhood cancer survivors became an important study population. In addition, the genome of apparently normal individuals seems to contain large numbers of alterations, including dozens to hundreds of nonfunctional alleles. With the number of mutational events in protein-coding genes estimated as less than one per genome after 1 gray (Gy) exposure, it is unsurprising that genetic effects from radiation have not yet been detected conclusively in humans. PMID:23988120

  14. Prediction of Geospace Radiation Environment and Solar Wind Parameters

    NASA Astrophysics Data System (ADS)

    Balikhin, Michael; Arber, Tony; Erdelyi, Robertus; Ganushkina, Natalya; van der Holst, Bart; Krasnoselskikh, Vladimir; Liemohn, Michael; Pakhotin, Ivan; Shprits, Yuri; Walker, Simon; Wik, Magnus; Wintoft, Peter; Yatsenko, Vitaliy

    2015-04-01

    Energetic electrons within the inner magnetosphere can cause both deep and surface charging of spacecraft operating at GEO and MEO orbits. Reliable forecast of the fluences of these electrons can assist in the mitigation of undesirable effects on spacecraft. Previous forecasts of these fluences exploited either system science or first principles based methodologies. The first, system science approach provides accurate forecasts of electron fluxes but is limited to regions in which continuous data are available, i.e. GEO. The second, based on physical principles, provides good coverage throughout the whole inner magnetosphere but with significantly lower accuracy. The combination of both approaches, as used in the SNB3GEO electron flux model (which combines the data driven NARMAX and physical VERB models), can overcome many of the short comings of the two individual models, generating improved short term forecasts for the whose RB region. Long term RB forecasts require the estimation of solar wind parameters at L1 based on remote solar observations. PROGRESS, a new Horizon 2020 funded project, aims to address these issues. This talk will provide a review of PROGRESS achievements, current status and aims for future development.

  15. Radiation dosimetry and biophysical models of space radiation effects

    NASA Technical Reports Server (NTRS)

    Cucinotta, Francis A.; Wu, Honglu; Shavers, Mark R.; George, Kerry

    2003-01-01

    Estimating the biological risks from space radiation remains a difficult problem because of the many radiation types including protons, heavy ions, and secondary neutrons, and the absence of epidemiology data for these radiation types. Developing useful biophysical parameters or models that relate energy deposition by space particles to the probabilities of biological outcomes is a complex problem. Physical measurements of space radiation include the absorbed dose, dose equivalent, and linear energy transfer (LET) spectra. In contrast to conventional dosimetric methods, models of radiation track structure provide descriptions of energy deposition events in biomolecules, cells, or tissues, which can be used to develop biophysical models of radiation risks. In this paper, we address the biophysical description of heavy particle tracks in the context of the interpretation of both space radiation dosimetry and radiobiology data, which may provide insights into new approaches to these problems.

  16. Radiative Effects of Aerosols

    NASA Technical Reports Server (NTRS)

    Valero, Francisco P. J.

    1997-01-01

    During the Atlantic Stratocumulus Transition Experiment (ASTEX) in June 1992, two descents in cloud-free regions allowed comparison of the change in aerosol optical depth as determined by an onboard total-direct-diffuse radiometer (TDDR) to the change calculated from measured size resolved aerosol microphysics and chemistry. Both profiles included pollution haze layer from Europe but the second also included the effect of a Saharan dust layer above the haze. The separate contributions of supermicrometer (coarse) and submicrometer (fine) aerosol were determined and thermal analysis of the pollution haze indicated that the fine aerosol was composed primarily of a sulfate/water mixture with a refractory soot-like core.

  17. Radiation Effects on Polymer Properties

    NASA Technical Reports Server (NTRS)

    Bouquet, F. L.; Winslow, J. W.

    1987-01-01

    Report compiles data on effects of radiation on physical properties of synthetic organic materials. Emphasis on materials of interest to nuclear-equipment and nuclear-reactor designers. Data covers five categories of polymeric materials: Insulators, elastomeric seals and gaskets, lubricants, adhesives, and coatings. More than 250 materials represented.

  18. Radiation effects on video imagers

    SciTech Connect

    Yates, G.J.; Bujnosek, J.J.; Jaramillo, S.A.; Walton, R.B.; Martinez, T.M.; Black, J.P.

    1985-01-01

    Radiation sensitivity of several photoconductive, photoemissive, and solid state silicon-based video imagers was measured by analyzing stored photocharge induced by irradiation with continuous and pulsed sources of high energy photons and neutrons. Transient effects as functions of absorbed dose, dose rate, fluences, and ionizing particle energy are presented.

  19. Radiation Effects in Graphite

    SciTech Connect

    Burchell, Timothy D

    2012-01-01

    The requirements for a solid moderator are reviewed and the reasons that graphite has become the solid moderator of choice discussed. The manufacture and properties of some currently available near-isotropic and isotropic grades are described. The major features of a graphite moderated reactors are briefly outlined. Displacement damage and the induced structural and dimensional changes in graphite are described. Recent characterization work on nano-carbons and oriented pyrolytic graphites that have shed new light on graphite defect structures are reviewed, and the effect of irradiation temperature on the defect structures is highlighted. Changes in the physical properties of nuclear graphite caused by neutron irradiation are reported. Finally, the importance of irradiation induced creep is presented, along with current models and their deficiencies.

  20. Radiative Effects of Aerosols

    NASA Technical Reports Server (NTRS)

    Valero, Francisco P. J.

    1996-01-01

    During the Atlantic Stratocumulus Transition Experiment (ASTEX) in June 1992, two descents in cloud-free regions allowed comparison of the change in aerosol optical depth as determined by an onboard total-direct-diffuse radiometer (TDDR) to the change calculated from measured size-resolved aerosol microphysics and chemistry. Both profiles included a pollution haze from Europe but the second also included the effect of a Saharan dust layer above the haze. The separate contributions of supermicrometer (coarse) and submicrometer (fine) aerosol were determined and thermal analysis of the pollution haze indicated that the fine aerosol was composed primarily of a sulfate/water mixture with a refractory soot-like core. The soot core increased the calculated extinction by about 10% in the most polluted drier layer relative to a pure sulfate aerosol but had significantly less effect at higher humidities. A 3 km descent through a boundary layer air mass dominated by pollutant aerosol with relative humidities (RH) 10-77% yielded a close agreement between the measured and calculated aerosol optical depths (550 nm) of 0.160 (+/- 0.07) and 0. 157 (+/- 0.034) respectively. During descent the aerosol mass scattering coefficient per unit sulfate mass varied from about 5 to 16 m(exp 2)/g and primarily dependent upon ambient RH. However, the total scattering coefficient per total fine mass was far less variable at about 4+/- 0.7 m(exp 2)/g. A subsequent descent through a Saharan dust layer located above the pollution aerosol layer revealed that both layers contributed similarly to aerosol optical depth. The scattering per unit mass of the coarse aged dust was estimated at 1.1 +/- 0.2 m(exp 2)/g. The large difference (50%) in measured and calculated optical depth for the dust layer exceeded measurements.

  1. Radiatively important parameters best estimate (RIPBE) value-added product (VAP)

    SciTech Connect

    Shippert,T.; Jensen,M.; McFarlane, S.; Mather, J.; Flynn, C.; Mlawer, E.; Delamere, J.; Oreopoulos, L.; Turner, D.; Xie, S.

    2010-03-15

    Currently, to calculate radiative heating rate profiles for the Broadband Heating Rate Profile (BBHRP) product, radiatively important parameters (water vapor, ozone, surface albedo, aerosol properties, and cloud properties) from multiple VAPs and datastreams are combined into input text files that are then used to run the RRTM radiative transfer codes. These input parameters have different temporal and spatial scales and are difficult to extract from the text files to be used for other purposes such as running other radiative transfer codes, analyzing results, or error tracking. The purpose of the Radiatively Important Parameters Best Estimate (RIPBE) VAP is to improve this process by creating a clearly identified set of inputs for BBHRP (and other radiation codes) on a uniform vertical and temporal grid. This process will decouple the input/output portion of the BBHRP from the core physics (the RRTM radiative transfer model) and will add error tracking and version information to the input data set. Critical parameters (which must exist for the radiation code to be run) will be designated; for other parameters, climatological or fixed values will be used when the preferred values are missing. This should increase the number of cases for which radiative transfer calculations can be run. In all cases, flags will clearly identify the source for each parameter. RIPBE will serve multiple functions: (1) it will provide a clearly identifiable set of inputs for BBHRP, (2) it will facilitate the use of BBHRP as a retrieval and radiation code development testbed by providing a vehicle for easily extracting and swapping input parameters needed to conduct radiative transfer calculations, and (3) it will be a complement to the Climate Modeling Best Estimate (CMBE) VAP and will provide a significantly expanded set of parameters for model evaluation in a showcase data set form. At the ASR meeting, we will present examples and evaluation of the initial RIPBE dataset at SGP.

  2. Bayesian parameter estimation for effective field theories

    NASA Astrophysics Data System (ADS)

    Wesolowski, Sarah; Klco, Natalie; Furnstahl, Richard; Phillips, Daniel; Thapilaya, Arbin

    2015-10-01

    We present a procedure based on Bayesian statistics for effective field theory (EFT) parameter estimation from experimental or lattice data. The extraction of low-energy constants (LECs) is guided by physical principles such as naturalness in a quantifiable way and various sources of uncertainty are included by the specification of Bayesian priors. Special issues for EFT parameter estimation are demonstrated using representative model problems, and a set of diagnostics is developed to isolate and resolve these issues. We apply the framework to the extraction of the LECs of the nucleon mass expansion in SU(2) chiral perturbation theory from synthetic lattice data.

  3. Mitigation of Space Radiation Effects

    NASA Astrophysics Data System (ADS)

    Atwell, William

    2012-02-01

    During low earth orbit and deep space missions, humans and spacecraft systems are exposed to high energy particles emanating from basically three sources: geomagnetically-trapped protons and electrons (Van Allen Belts), extremely high energy galactic cosmic radiation (GCR), and solar proton events (SPEs). The particles can have deleterious effects if not properly shielded. For humans, there can be a multitude of harmful effects depending on the degree of exposure. For spacecraft systems, especially electronics, the effects can range from single event upsets (SEUs) to catastrophic effects such as latchup and burnout. In addition, some materials, radio-sensitive experiments, and scientific payloads are subject to harmful effects. To date, other methods have been proposed such as electrostatic and electromagnetic shielding, but these approaches have not proven feasible due to cost, weight, and safety issues. The only method that has merit and has been effective is bulk or parasitic shielding. In this paper, we discuss in detail the sources of the space radiation environment, spacecraft, human, and onboard systems modeling methodologies, transport of these particles through shielding materials, and the calculation of the dose effects. In addition, a review of the space missions to date and a discussion of the space radiation mitigation challenges for lunar and deep space missions such as lunar outposts and human missions to Mars are presented.

  4. Atmospheric effects on radiation measurements

    NASA Technical Reports Server (NTRS)

    Jurica, G. M.

    1973-01-01

    Two essentially distinct regions of the electromagnetic spectrum are discussed: (1) the scattering region in which the radiation energy is provided by the incident solar flux; and (2) the infrared region in which emission by the earth's surface and atmospheric gases supply radiative energy. In each of these spectral regions the atmosphere performs its dual function with respect to a remote sensing measurement of surface properties. The atmosphere acts both as a filter and as a noise generator removing and obscuring sought after information. Nevertheless, with proper application of concepts such as have been considered, it will be possible to remove these unwanted atmospheric effects and to improve identification techniques being developed.

  5. Radiation effects in spacecraft electronics

    NASA Technical Reports Server (NTRS)

    Raymond, James P.

    1989-01-01

    Effects on the internal spacecraft electronics due to exposure to the natural and enhanced space radiation environment will be reviewed. The emphasis will be placed on the description of the nature of both the exposure environment and failure mechanisms in semiconductors. Understanding both the system environment and device effects is critical in the use of laboratory simulation environments to obtain the data necessary to design and qualify components for successful application.

  6. Retrieval of cloud microphysical parameters from INSAT-3D: a feasibility study using radiative transfer simulations

    NASA Astrophysics Data System (ADS)

    Jinya, John; Bipasha, Paul S.

    2016-05-01

    Clouds strongly modulate the Earths energy balance and its atmosphere through their interaction with the solar and terrestrial radiation. They interact with radiation in various ways like scattering, emission and absorption. By observing these changes in radiation at different wavelength, cloud properties can be estimated. Cloud properties are of utmost importance in studying different weather and climate phenomena. At present, no satellite provides cloud microphysical parameters over the Indian region with high temporal resolution. INSAT-3D imager observations in 6 spectral channels from geostationary platform offer opportunity to study continuous cloud properties over Indian region. Visible (0.65 μm) and shortwave-infrared (1.67 μm) channel radiances can be used to retrieve cloud microphysical parameters such as cloud optical thickness (COT) and cloud effective radius (CER). In this paper, we have carried out a feasibility study with the objective of cloud microphysics retrieval. For this, an inter-comparison of 15 globally available radiative transfer models (RTM) were carried out with the aim of generating a Look-up- Table (LUT). SBDART model was chosen for the simulations. The sensitivity of each spectral channel to different cloud properties was investigated. The inputs to the RT model were configured over our study region (50°S - 50°N and 20°E - 130°E) and a large number of simulations were carried out using random input vectors to generate the LUT. The determination of cloud optical thickness and cloud effective radius from spectral reflectance measurements constitutes the inverse problem and is typically solved by comparing the measured reflectances with entries in LUT and searching for the combination of COT and CER that gives the best fit. The products are available on the website www.mosdac.gov.in

  7. Radiative reactions in halo effective field theory

    NASA Astrophysics Data System (ADS)

    Rupak, Gautam

    2016-03-01

    In this article we review the recent progress in radiative reaction calculations in halo effective field theory. We look at radiative capture and breakup processes that involve a halo nucleus with a single valence neutron or proton. Looking at 7Li(n,γ) 8Li,14C(n,γ)15C and related reactions, the dominant source of theoretical uncertainty in s- and p-wave halo nuclei reaction calculations is quantified in a model-independent framework. The analysis for neutron halos is extended to proton halo systems. The effective field theory results quantify which observable parameters of the strong interaction at low energy need to be determined more precisely for accurate cross-section calculations.

  8. Longwave radiation budget parameters computed from ISCCP and HIRS2/MSU products

    NASA Technical Reports Server (NTRS)

    Wu, Man L. C.; Chang, Lang-Ping

    1992-01-01

    The International Satellite Cloud Climatology Project (ISCCP) retrieved cloud fields and the high-resolution radiation sounder 2 (HIRS2) retrieved cloud fields yield similar outgoing longwave radiation (OLR) due to the cancelation effect of cloud-top altitudes and cloud amount on OLR. For the large regional discrepancies of the order of 30 W/sq m found over northern Africa are largely due to surface temperature differences, and extensive discrepancies over the ocean are due to humidity differences. Harmonic analysis is applied to OLR, clear-sky OLR, and cloud-radiative forcing at the top of the atmosphere using the ISCCP products. The diurnal variations of these parameters from 60 deg S to 60 deg N are larger over land than over the ocean. The clear-sky OLR peaks around 1500 LST, usually over land areas, and is associated with the surface/air temperature maximum. The OLR over cloudy regions shows a similar diurnal phase as the cloud top pressure. The cloud radiative forcing at the top of the atmosphere has maximum value near 2100 LST mountain areas and near 0000 and 0300 LST over equatorial regions. The ISCCP-computed longwave cloud radiative forcing has smaller diurnal variations over the ocean than the HIRS2-computed longwave cloud radiative forcing. The global mean bias of OLR is around 0.74 W/sq m, and locally, the bias can be as large as 5 to 10 W/sq m. This appears to indicate that the twice-a-day measurements of the HIRS2/MSU (around 0315 and 1515 LST, which are the equatorial cross times at nadir track) can be used to derive monthly mean OLR without significant bias.

  9. [Health effects of ultraviolet radiation].

    PubMed

    Ohnaka, T

    1993-01-01

    Exposure to ultraviolet radiation (UVR) occurs from both natural and artificial sources. The main natural source is the sun. On the other hand, artificial UVR sources are widely used in industry and also used in hospitals, laboratories, etc. because of their germicidal properties. They are even used for cosmetic purposes. UVR can be classified into three regions according to its wavelength: as UVA (320-400nm), UVB (320-280nm) and UVC (280-200nm). The UVC has the greatest health effect on humans among the three. The sun radiates a wide range of spectrum of electromagnetic radiation including the UVR, however the radiation below 290 nm in wavelength does not reach the surface of the earth for effective absorption by the stratospheric ozone layer. As a result, UVR from a natural source consists of only UVA and a part of UVB. On the other hand, artificial UVR sources include UVC region and have serious effects on the human body, especially on the skin and eyes. The health effects of UVR on humans can be beneficial or detrimental, depending on the amount and form of UVR, as well as on the skin type of the individual exposed. It has been acknowledged that a long period of UVR deficiency may have harmful effects on the human body, such as the development of vitamin D deficiency and rickets in children due to a disturbance in the phosphorus and calcium metabolism. Appropriate measures to increase the amount of exposure to UVR, especially to UVB radiation by the use of sun bathing, the exposure to artificial UVR sources, etc. have shown to prevent disease states caused by UVR deficiency. The harmful effects of UVR consist of erythema, sunburn, photodamage (photoaging), photocarcinogenesis, damage to the eyes, alteration of the immune system of the skin, and chemical hypersensitivity. Skin cancer is commonly produced by UVR. In this review, various states of UV from solar radiation and the degree of exposure to UVR are introduced. The benefits and harmful health effects of

  10. Thermal effects in radiation processing

    SciTech Connect

    Zagorski, Z.P.

    1984-10-21

    The balance of ionizing radiation energy incident on an object being processed is discussed in terms of energy losses, influencing the amount really absorbed. To obtain the amount of heat produced, the absorbed energy is corrected for the change in internal energy of the system and for the heat effect of secondary reactions developing after the initiation. The temperature of a processed object results from the heat evolved and from the specific heat of the material comprising the object. The specific heat of most materials is usually much lower than that of aqueous systems and therefore temperatures after irradiation are higher. The role of low specific heat in radiation processing at cryogenic conditions is stressed. Adiabatic conditions of accelerator irradiation are contrasted with the steady state thermal conditions prevailing in large gamma sources. Among specific questions discussed in the last part of the paper are: intermediate and final temperature of composite materials, measurement of real thermal effects in situ, neutralization of undesired warming experienced during radiation processing, processing at temperatures other than ambient and administration of very high doses of radiation.

  11. Effects of contamination on radioligand binding parameters.

    PubMed

    Lazareno, S; Birdsall, N J

    2000-02-01

    Radioligand binding studies are used to provide quantitative estimates of parameters such as the receptor density of a tissue and the affinity values of labelled and unlabelled ligands. The presence of an unlabelled competing contaminant, which might be present because of actual contamination, inadequate radioligand purification or the breakdown of the radioligand to an active species, has surprising effects on these estimates: the apparent affinity of the radioligand is increased but the Ki values of unlabelled ligands are unaffected. The most striking and sensitive effects are on radioligand association kinetics, which become independent of radioligand concentration at high radioligand concentrations. PMID:10664609

  12. The Effect of Directional Radiation Models on the Interpretation of Earth Radiation Budget Measurements.

    NASA Astrophysics Data System (ADS)

    Green, Richard N.

    1980-10-01

    A parameter estimation technique is presented to estimate the radiative flux density distribution over the earn from a set of radiometer measurements at satellite altitude. The technique analyzes measurements from a wide field of view, horizon to horizon. nadir pointing sensor with a mathematical technique to derive the radiative flux density estimates at the top of the atmosphere for resolution elements smaller than the sensor field of view. A computer simulation of the data analysis technique is presented for both earth-emitted and reflected radiation.The errors resulting from the assumed directional radiation model, spatial model and random measurement error have little effect an the global mean radiation. Zonal estimates were found to be more sensitive, to the spatial model than to the directional radiation model. Results from analysing medium field of view measurements showed a much greater sensitivity to the directional radiation model, even on a global scale.

  13. Bayesian parameter estimation for effective field theories

    NASA Astrophysics Data System (ADS)

    Wesolowski, S.; Klco, N.; Furnstahl, R. J.; Phillips, D. R.; Thapaliya, A.

    2016-07-01

    We present procedures based on Bayesian statistics for estimating, from data, the parameters of effective field theories (EFTs). The extraction of low-energy constants (LECs) is guided by theoretical expectations in a quantifiable way through the specification of Bayesian priors. A prior for natural-sized LECs reduces the possibility of overfitting, and leads to a consistent accounting of different sources of uncertainty. A set of diagnostic tools is developed that analyzes the fit and ensures that the priors do not bias the EFT parameter estimation. The procedures are illustrated using representative model problems, including the extraction of LECs for the nucleon-mass expansion in SU(2) chiral perturbation theory from synthetic lattice data.

  14. Assessing the impact of radiative parameter uncertainty on plant growth simulation

    NASA Astrophysics Data System (ADS)

    Viskari, T.; Serbin, S.; Dietze, M.; Shiklomanov, A. N.

    2015-12-01

    Current Earth system models do not adequately project either the magnitude or the sign of carbon fluxes and storage associated with the terrestrial carbon cycle resulting in significant uncertainties in their potential feedbacks on the future climate system. A primary reason for the current uncertainty in these models is the lack of observational constraints of key biomes at relevant spatial and temporal scales. There is an increasingly large and highly resolved amount of remotely sensed observations that can provide the critical model inputs. However, effectively incorporating these data requires the use of radiative transfer models and their associated assumptions. How these parameter assumptions and uncertainties affect model projections for, e.g., leaf physiology, soil temperature or growth has not been examined in depth. In this presentation we discuss the use of high spectral resolution observations at the near surface to landscape scales to inform ecosystem process modeling efforts, particularly the uncertainties related to properties describing the radiation regime within vegetation canopies and the impact on C cycle projections. We illustrate that leaf and wood radiative properties and their associated uncertainties have an important impact on projected forest carbon uptake and storage. We further show the need for a strong data constraint on these properties and discuss sources of this remotely sensed information and methods for data assimilation into models. We present our approach as an efficient means for understanding and correcting implicit assumptions and model structural deficiencies in radiation transfer in vegetation canopies. Ultimately, a better understanding of the radiation balance of ecosystems will improve regional and global scale C and energy balance projections.

  15. Radiative Corrections to Asymmetry Parameter in the {Omega}{sup -{yields}{Lambda}}+K{sup -} Decay

    SciTech Connect

    Queijeiro, A.

    2010-07-29

    We compute the radiative corrections, to first order in the fine structure constant {alpha}, to the asymmetry parameter {alpha}{sub {Omega}}of the {Omega}{sup -{yields}{Lambda}}+K{sup -} decay. We use previous results where Sirlin's procedure is used to separate the radiative corrections into two parts, one independent model contribution and a model dependent one.

  16. Effect of microwave radiation on Jayadhar cotton fibers: WAXS studies

    SciTech Connect

    Niranjana, A. R. Mahesh, S. S. Divakara, S. Somashekar, R.

    2014-04-24

    Thermal effect in the form of micro wave energy on Jayadhar cotton fiber has been investigated. Microstructural parameters have been estimated using wide angle x-ray scattering (WAXS) data and line profile analysis program developed by us. Physical properties like tensile strength are correlated with X-ray results. We observe that the microwave radiation do affect significantly many parameters and we have suggested a multivariate analysis of these parameters to arrive at a significant result.

  17. Radiatively Important Parameters Best Estimate (RIPBE): An ARM Value-Added Product

    SciTech Connect

    McFarlane, S; Shippert, T; Mather, J

    2011-06-30

    The Radiatively Important Parameters Best Estimate (RIPBE) VAP was developed to create a complete set of clearly identified set of parameters on a uniform vertical and temporal grid to use as input to a radiative transfer model. One of the main drivers for RIPBE was as input to the Broadband Heating Rate Profile (BBHRP) VAP, but we also envision using RIPBE files for user-run radiative transfer codes, as part of cloud/aerosol retrieval testbeds, and as input to averaged datastreams for model evaluation.

  18. Effects of different doses of low power continuous wave he-ne laser radiation on some seed thermodynamic and germination parameters, and potential enzymes involved in seed germination of sunflower (Helianthus annuus L.).

    PubMed

    Perveen, Rashida; Ali, Qasim; Ashraf, Muhammad; Al-Qurainy, Fahad; Jamil, Yasir; Raza Ahmad, Muhammad

    2010-01-01

    In this study, water-soaked seeds of sunflower were exposed to He-Ne laser irradiation of different energies to determine whether or not He-Ne laser irradiation caused changes to seed thermodynamic and germination parameters as well as effects on the activities of germination enzymes. The experiment comprised four energy levels: 0 (control), 100, 300 and 500mJ of laser energy and each treatment replicated four times arranged in a completely randomized design. The experimentation was performed under the greenhouse conditions in the net-house of the Department of Botany, University of Agriculture, Faisalabad. The seed thermodynamic parameters were calculated according to seed germination thermograms determined with a calorimeter at 25.8°C for 72h. Various thermodynamic parameters of seed (ΔH, (ΔS)(e), (ΔS)(c), (ΔS)(e) /Δt and (ΔS)(c) /Δt) were affected significantly due to presowing laser treatment. Significant changes in seed germination parameters and enzyme activities were observed in seeds treated with He-Ne laser. The He-Ne laser seed treatment resulted in increased activities of amylase and protease. These results indicate that the low power continuous wave He-Ne laser light seed treatment has considerable biological effects on seed metabolism. This seed treatment technique can be potentially employed to enhance agricultural productivity. PMID:20670360

  19. [MODIFICATION OF THE PROTON BEAM PHYSICAL PARAMETERS AND RADIOBIOLOGICAL CHARACTERISTICS BY ELEMENTS OF SPACECRAFT RADIATION PROTECTION].

    PubMed

    Ivanov, A A; Molokanov, A G; Shurshakov, V A; Bulynina, T M; Liakhova, K N; Severiukhin, Yu S; Abrosimova, A N; Ushakov, I B

    2015-01-01

    The experiment was performed with outbred ICR (CD-1). female mice (SPF). The animals were irradiated by 171 MeV protons at a dose of 20 cGy. The spacecraft radiation protection elements used in the experiment were a construction of wet hygiene wipes called a "protective blind", and a glass plate imitating an ISS window. Physical obstacles on the path of 171 MeV protons increase their linear energy transfer leading to the absorbed dose elevation and strengthening of the radiobiological effect. In the experiment, two types of obstacles together raised the absorbed dose from 20 to 23.2 cGy. Chemically different materials (glass and water in the wipes) were found to exert unequal modifying effects on physical and biological parameters of the proton-irradiated mice. There was a distinct dose-dependent reduction of bone marrow cellularity within the dose range from 20 cGy to 23.2 cGy in 24 hours after exposure. No modifying effect of the radiation protection elements on spontaneous motor activity was discovered when compared with entrance protons. The group of animals protected by the glass plate exhibited normal orientative-trying reactions and weakened grip with the forelimbs. Rationalization of physical methods of spacecrew protection should be based as on knowledge in physical dosimetry (ionizing chambers, thermoluminescent, track detectors etc.), so the radiobiological criteria established in experiments with animals. PMID:26738306

  20. RADIATION EFFECTS IN MATERIAL MICROSTRUCTURE.

    SciTech Connect

    SIMOS,N.

    2007-05-30

    Next generation nuclear power systems, high-power particle accelerators and space technology will inevitably rely on higher performance materials that will be able to function in the extreme environments of high irradiation, high temperatures, corrosion and stress. The ability of any material to maintain its functionality under exposure to harsh conditions is directly linked to the material structure at the nano- and micro-scales. Understanding of the underlying processes is key to the success of such undertakings. This paper presents experimental results of the effects of radiation exposure on several unique alloys, composites and crystals through induced changes in the physio-mechanical macroscopic properties.

  1. Parameter estimation applied to Nimbus 6 wide-angle longwave radiation measurements

    NASA Technical Reports Server (NTRS)

    Green, R. N.; Smith, G. L.

    1978-01-01

    A parameter estimation technique was used to analyze the August 1975 Nimbus 6 Earth radiation budget data to demonstrate the concept of deconvolution. The longwave radiation field at the top of the atmosphere is defined from satellite data by a fifth degree and fifth order spherical harmonic representation. The variations of the major features of the radiation field are defined by analyzing the data separately for each two-day duty cycle. A table of coefficient values for each spherical harmonic representation is given along with global mean, gradients, degree variances, and contour plots. In addition, the entire data set is analyzed to define the monthly average radiation field.

  2. The Brookhaven Radiation Effects Facility

    NASA Astrophysics Data System (ADS)

    Grand, P.; Snead, C. L.; Ward, T.

    The Neutral Particle Beam Radiation Effects Facility (REF), funded by the SDIO through the Defense Nuclear Agency and the Air Force Weapons Laboratory, has been constructed at Brookhaven National Laboratory. The operation started in October 1986. The REF is capable of delivering pulsed H(-), H(0), and H(+) beams of 100 to 200 MeV energy at up to 30 mA peak current. Pulses can be adjusted from 5-micron to 500-micron length at a repetition rate of 5 pps. The beam spot on target is adjustable from 3 to 100 cm diameter (2 sigma), resulting in a maximum dose of about 10 MRad (Si) per pulse (small beam spot). Experimental use of the REF is being primarily supported by the SDI lethality program. The program has addressed ionization effects in electronics, both dose rate and total dose dependence, radiation-sensitive components, and dE/dx effects in energetic materials including propellants and high explosives. This paper describes the REF, its capabilities and potential, and the experiments that have been carried out to date or are being planned.

  3. [Estimation of Fraction of Absorbed Photosynthetically Active Radiation for Winter Wheat Based on Hyperspectral Characteristic Parameters].

    PubMed

    Zhang, Chao; Cai, Huan-jie; Li, Zhi-jun

    2015-09-01

    Estimating fraction of absorbed photosynthetically active radiation (FPAR) precisely has great importance for detecting vegetation water content, energy and carbon cycle balance. Based on this, ASD FieldSpec 3 and SunScan canopy analyzer were applied to measure the canopy spectral reflectance and photosynthetically active radiation over whole growth stage of winter wheat. Canopy reflectance spectral data was used to build up 24 hyperspectral characteristic parameters and the correlation between FPAR and different spectral characteristic parameters were analyzed to establish the estimation model of FPAR for winter wheat. The results indicated that there were extremely significant correlations (p<0.01) between FPAR and hyperspectral characteristic parameters except the slope of blue edge (Db). The correlation coefficient between FPAR and the ratio of red edge area to blue edge area (VI4) was the highest, reaching at 0.836. Seven spectral parameters with higher correlation coefficient were selected to establish optimal linear and nonlinear estimation models of FPAR, and the best estimating models of FPAR were obtained by accuracy analysis. For the linear model, the inversin model between green edge and FPAR was the best, with R2, RMSE and RRMSE of predicted model reaching 0.679, 0.111 and 20.82% respectively. For the nonlinear model, the inversion model between VI2 (normalized ratio of green peak to red valley of reflectivity) and FPAR was the best, with R2, RMSE and RRMSE of predicted model reaching 0.724, 0.088 and 21.84% for. In order to further improve the precision of the model, the multiple linear regression and BP neural network methods were used to establish models with multiple high spectral parameters BP neural network model (R2=0.906, RMSE=0.08, RRMSE=16.57%) could significantly improve the inversion precision compared with the single variable model. The results show that using hyperspectral characteristic parameters to estimate FPAR of winter wheat is

  4. Estimation of Radiobiologic Parameters and Equivalent Radiation Dose of Cytotoxic Chemotherapy in Malignant Glioma

    SciTech Connect

    Jones, Bleddyn . E-mail: b.jones.1@bham.ac.uk; Sanghera, Paul

    2007-06-01

    Purpose: To determine the radiobiologic parameters for high-grade gliomas. Methods and Materials: The biologic effective dose concept is used to estimate the {alpha}/{beta} ratio and K (dose equivalent for tumor repopulation/d) for high-grade glioma patients treated in a randomized fractionation trial. The equivalent radiation dose of temozolomide (Temodar) chemotherapy was estimated from another randomized study. The method assumes that the radiotherapy biologic effective dose is proportional to the adjusted radiotherapy survival duration of high-grade glioma patients. Results: The median tumor {alpha}/{beta} and K estimate is 9.32 Gy and 0.23 Gy/d, respectively. Using the published surviving fraction after 2-Gy exposure (SF{sub 2}) data, and the above {alpha}/{beta} ratio, the estimated median {alpha} value was 0.077 Gy{sup -1}, {beta} was 0.009 Gy{sup -2}, and the cellular doubling time was 39.5 days. The median equivalent biologic effective dose of temozolomide was 11.03 Gy{sub 9.3} (equivalent to a radiation dose of 9.1 Gy given in 2-Gy fractions). Random sampling trial simulations based on a cure threshold of 70 Gy in high-grade gliomas have shown the potential increase in tumor cure with dose escalation. Partial elimination of hypoxic cells (by chemical hypoxic cell sensitizers or carbon ion therapy) has suggested that considerable gains in tumor control, which are further supplemented by temozolomide, are achievable. Conclusion: The radiobiologic parameters for human high-grade gliomas can be estimated from clinical trials and could be used to inform future clinical trials, particularly combined modality treatments with newer forms of radiotherapy. Other incurable cancers should be studied using similar radiobiologic analysis.

  5. Estimating stellar effective temperatures and detected angular parameters using stochastic particle swarm optimization

    NASA Astrophysics Data System (ADS)

    Zhang, Chuan-Xin; Yuan, Yuan; Zhang, Hao-Wei; Shuai, Yong; Tan, He-Ping

    2016-09-01

    Considering features of stellar spectral radiation and sky surveys, we established a computational model for stellar effective temperatures, detected angular parameters and gray rates. Using known stellar flux data in some bands, we estimated stellar effective temperatures and detected angular parameters using stochastic particle swarm optimization (SPSO). We first verified the reliability of SPSO, and then determined reasonable parameters that produced highly accurate estimates under certain gray deviation levels. Finally, we calculated 177 860 stellar effective temperatures and detected angular parameters using data from the Midcourse Space Experiment (MSX) catalog. These derived stellar effective temperatures were accurate when we compared them to known values from literatures. This research makes full use of catalog data and presents an original technique for studying stellar characteristics. It proposes a novel method for calculating stellar effective temperatures and detecting angular parameters, and provides theoretical and practical data for finding information about radiation in any band.

  6. Effects of radiation on laser diodes.

    SciTech Connect

    Phifer, Carol Celeste

    2004-09-01

    The effects of ionizing and neutron radiation on the characteristics and performance of laser diodes are reviewed, and the formation mechanisms for nonradiative recombination centers, the primary type of radiation damage in laser diodes, are discussed. Additional topics include the detrimental effects of aluminum in the active (lasing) volume, the transient effects of high-dose-rate pulses of ionizing radiation, and a summary of ways to improve the radiation hardness of laser diodes. Radiation effects on laser diodes emitting in the wavelength region around 808 nm are emphasized.

  7. Salivary biochemical markers as potential acute toxicity parameters for acute radiation injury: A study on small experimental animals.

    PubMed

    Soni, S; Agrawal, P; Kumar, N; Mittal, G; Nishad, D K; Chaudhury, N K; Bhatnagar, A; Basu, M; Chhillar, N

    2016-03-01

    Researchers have been evaluating several biodosimetric/screening approaches to assess acute radiation injury, related to mass causality. Keeping in mind this background, we hypothesized that effect of whole-body irradiation in single fraction in graded doses can affect the secretion of various salivary components that could be used as acute radiation injury/toxicity marker, which can be used in screening of large population at the time of nuclear accidents/disaster. Thirty Sprague Dawley rats treated with whole-body cobalt-60 gamma irradiation of dose 1-5 Gy (dose rate: 0.95 Gy/min) were included in this study. Whole mixed saliva was collected from all animals before and after radiation up to 72 h postradiation. Saliva was analyzed for electrolytes, total protein, urea, and amylase. Intragroup comparison of salivary parameters at different radiation doses showed significant differences. Potassium was significantly increased as the dose increased from 1 Gy to 5 Gy (p < 0.01) with effect size of difference (r > 0.5). Sodium was significantly altered after 3-5 Gy (p < 0.01, r > 0.5), except 1 and 2 Gy, whereas changes in sodium level were nonsignificant (p > 0.5). Urea, total protein, and amylase levels were also significantly increased as the radiation dose increased (p < 0.01) with large effect size of difference (r > 0.5). This study suggests that salivary parameters were sensitive toward radiation even at low radiation dose which can be used as a predictor of radiation injury. PMID:25813962

  8. Effects of process parameters on hydrothermal carbonization

    NASA Astrophysics Data System (ADS)

    Uddin, Md. Helal

    In recent years there has been increased research activity in renewable energy, especially upgrading widely available lignicellulosic biomass, in a bid to counter the increasing environmental concerns related with the use of fossil fuels. Hydrothermal carbonization (HTC), also known as wet torrefaction or hot water pretreatment, is a process for pretreatment of diverse lignocellulosic biomass feedstocks, where biomass is treated under subcritical water conditions in short contact time to produce high-value products. The products of this process are: a solid mass characterized as biochar/biocoal/biocarbon, which is homogeneous, energy dense, and hydrophobic; a liquid stream composed of five and six carbon sugars, various organic acids, and 5-HMF; and a gaseous stream, mainly CO2. A number of process parameters are considered important for the extensive application of the HTC process. Primarily, reaction temperature determines the characteristics of the products. In the solid product, the oxygen carbon ratio decreases with increasing reaction temperature and as a result, HTC biochar has the similar characteristics to low rank coal. However, liquid and gaseous stream compositions are largely correlated with the residence time. Biomass particle size can also limit the reaction kinetics due to the mass transfer effect. Recycling of process water can help to minimize the utility consumption and reduce the waste treatment cost as a result of less environmental impact. Loblolly pine was treated in hot compressed water at 200 °C, 230 °C, and 260 °C with 5:1 water:biomass mass ratio to investigate the effects of process parameters on HTC. The solid product were characterized by their mass yields, higher heating values (HHV), and equilibrium moisture content (EMC), while the liquid were characterized by their total organic carbon content and pH value.

  9. Effective UV radiation from model calculations and measurements

    NASA Technical Reports Server (NTRS)

    Feister, Uwe; Grewe, Rolf

    1994-01-01

    Model calculations have been made to simulate the effect of atmospheric ozone and geographical as well as meteorological parameters on solar UV radiation reaching the ground. Total ozone values as measured by Dobson spectrophotometer and Brewer spectrometer as well as turbidity were used as input to the model calculation. The performance of the model was tested by spectroradiometric measurements of solar global UV radiation at Potsdam. There are small differences that can be explained by the uncertainty of the measurements, by the uncertainty of input data to the model and by the uncertainty of the radiative transfer algorithms of the model itself. Some effects of solar radiation to the biosphere and to air chemistry are discussed. Model calculations and spectroradiometric measurements can be used to study variations of the effective radiation in space in space time. The comparability of action spectra and their uncertainties are also addressed.

  10. Radiation effects in the environment

    SciTech Connect

    Begay, F.; Rosen, L.; Petersen, D.F.; Mason, C.; Travis, B.; Yazzie, A.; Isaac, M.C.P.; Seaborg, G.T.; Leavitt, C.P.

    1999-04-01

    Although the Navajo possess substantial resource wealth-coal, gas, uranium, water-this potential wealth has been translated into limited permanent economic or political power. In fact, wealth or potential for wealth has often made the Navajo the victims of more powerful interests greedy for the assets under limited Navajo control. The primary focus for this education workshop on the radiation effects in the environment is to provide a forum where scientists from the nuclear science and technology community can share their knowledge toward the advancement and diffusion of nuclear science and technology issues for the Navajo public. The scientists will make an attempt to consider the following basic questions; what is science; what is mathematics; what is nuclear radiation? Seven papers are included in this report: Navajo view of radiation; Nuclear energy, national security and international stability; ABC`s of nuclear science; Nuclear medicine: 100 years in the making; Radon in the environment; Bicarbonate leaching of uranium; and Computational methods for subsurface flow and transport. The proceedings of this workshop will be used as a valuable reference materials in future workshops and K-14 classrooms in Navajo communities that need to improve basic understanding of nuclear science and technology issues. Results of the Begay-Stevens research has revealed the existence of strange and mysterious concepts in the Navajo Language of nature. With these research results Begay and Stevens prepared a lecture entitled The Physics of Laser Fusion in the Navajo language. This lecture has been delivered in numerous Navajo schools, and in universities and colleges in the US, Canada, and Alaska.

  11. Occupational exposure and its effect on some immune parameters

    SciTech Connect

    Tuschl, H.; Steger, F.; Kovac, R.

    1995-01-01

    Some immunological parameters were investigated in a group of workers exposed to external radiation (1.4 to 9.8 mSy) and inhalation of tritium (comm. eff. dose equiv. 1.2 to 2.8 mSv). The present investigations indicate the differential radiosensitivity of lymphocytic subsets: CD8 positive suppressor T cells were found to be the most sensitive subpopulation in the peripheral blood of radiation exposed workers. CD4/CD8 ratios were increased mainly due to an increase in absolute numbers of CD4 positive helper T cells indicating a selective cell renewal after irradiation. Results obtained after phytohaemugglutinin stimulation of lymphocytes showed individual variation, though there seems to be a trend towards an inverse correlation between absolute T cell numbers in peripheral blood and the number of S phases observed after stimulation, low T cell numbers leading to a high rate of stimulation. The calculation of the committed effective dose equivalents show that radiation protection against internal tritium contaminants should not be neglected. 21 refs., 3 figs., 5 tabs.

  12. Spallation radiation effects in materials

    SciTech Connect

    Mansur, L.K.; Farrell, K.; Wechsler, M.S.

    1996-06-01

    Spallation refers to the process whereby particles (chiefly neutrons) are ejected from nuclei upon bombardment by high-energy protons. Spallation neutron sources (SNS`s) use these neutrons for neutron scattering and diffraction research, and SNS`s are proposed as the basis for systems for tritium production and transmutation of nuclear waste. Materials in SNS`s are exposed to the incident proton beam (energies typically about 1000 MeV) and to the spallation neutrons (spectrum of energies extending up to about 1000 MeV). By contrast the fission neutrons in nuclear reactors have an average energy of only about 2 MeV, and the neutrons in fusion reactors would have energies below about 14 MeV. Furthermore, the protons and neutrons in SNS`s for scattering and diffraction research are pulsed at frequencies of about 10 to 60 Hz, from which significant changes in the kinetics of point and extended defects may be expected. In addition, much higher transmutation rates occur in SNS-irradiated materials, On the whole, then, significant differences in microstructural development and macroscopic properties may result upon exposure in SNS systems, as compared with fission and fusion irradiations. In a more general sense, subjecting materials to new radiation environments has almost routinely led to new discoveries. To the extent that data are avaiable, however, the spallation environment appears to increase the degree of damage without introducing totally new effects. The first part of this presentation is an overview of radiation effects in materials, outlining essential concepts and property changes and their physical bases. This background is followed by a description of SNS irradiation environments and the effects on materials of exposure to these environments. A special discussion is given of the selection of target (e.g., liquid mercury), container (e.g., austenitic stainless steel or ferritic/martensitic steel), and structural materials in SNS systems.

  13. Material Effectiveness for Radiation Shielding

    NASA Technical Reports Server (NTRS)

    2003-01-01

    Materials with a smaller mean atomic mass, such as lithium (Li) hydride and polyethylene, make the best radiation shields for astronauts. The materials have a higher density of nuclei and are better able to block incoming radiation. Also, they tend to produce fewer and less dangerous secondary particles after impact with incoming radiation.

  14. Rapid calculation of terrain parameters for radiation modeling from digital elevation data

    NASA Technical Reports Server (NTRS)

    Dozier, Jeff; Frew, James

    1990-01-01

    Digital elevation models are now widely used to calculate terrain parameters to determine incoming solar and longwave radiation for use in surface climate models, interpretation of remote-sensing data, and parameters in hydrologic models. Because of the large number of points in an elevation grid, fast algorithms are useful to save computation time. A description is given of rapid methods for calculating slope and azimuth, solar illumination angle, horizons, and view factors for radiation from sky and terrain. Calculation time is reduced by fast algorithms and lookup tables.

  15. A survey of space radiation effects

    NASA Technical Reports Server (NTRS)

    Hill, C. W.

    1980-01-01

    The effects of space radiation and its significance for space missions, as they increase in scope, duration, and complexity are discussed. Type of radiation hazard may depend on location or on special equipment used. It is emphasized that it is necessary to search for potential radiation problems in the design stage of a mission. Problem areas such as radiation damage to solar cells and the revolutionary advances are discussed. Radiation effect to electronics components other than solar cells, and several specialized areas such as radioactivity and luminescence are also examined.

  16. Dosimetry and Biological Effects of Ionizing Radiation

    NASA Astrophysics Data System (ADS)

    Kanyár, B.; Köteles, G. J.

    The extension of the use of ionizing radiation and the new biological information on the effects of radiation exposure that is now becoming available, present new challenges to the development of concepts and methodology in determination of doses and assessment of hazards for the protection of living systems. Concise information is given on the deterministic and stochastic effects, on the debate concerning the effects of low doses, the detection of injuries by biological assays, and the radiation sickness.

  17. Beam Echo Effect for Generation of Short-Wavelength Radiation

    SciTech Connect

    Stupakov, G.; /SLAC

    2009-12-09

    The Echo-Enabled Harmonic Generation (EEHG) FEL uses two modulators in combination with two dispersion sections to generate a high-harmonic density modulation starting with a relatively small initial energy modulation of the beam. After presenting the concept of the EEHG, we address several practically important issues, such as the effect of coherent and incoherent synchrotron radiation in the dispersion sections. Using a representative realistic set of beam parameters, we show how the EEHG scheme enhances the FEL performance and allows one to generate a fully (both longitudinally and transversely) coherent radiation. We then discuss application of the echo modulation for generation of attosecond pulses of radiation, and also using echo for generation of terahertz radiation. We present main parameters of a proof-of-principle experiment currently being planned at SLAC for demonstration of the echo modulation mechanism.

  18. Potential health effects of space radiation

    NASA Technical Reports Server (NTRS)

    Yang, Chui-Hsu; Craise, Laurie M.

    1993-01-01

    Crewmembers on missions to the Moon or Mars will be exposed to radiation belts, galactic cosmic rays, and possibly solar particle events. The potential health hazards due to these space radiations must be considered carefully to ensure the success of space exploration. Because there is no human radioepidemiological data for acute and late effects of high-LET (Linear-Energy-Transfer) radiation, the biological risks of energetic charged particles have to be estimated from experimental results on animals and cultured cells. Experimental data obtained to date indicate that charged particle radiation can be much more effective than photons in causing chromosome aberrations, cell killing, mutation, and tumor induction. The relative biological effectiveness (RBE) varies with biological endpoints and depends on the LET of heavy ions. Most lesions induced by low-LET radiation can be repaired in mammalian cells. Energetic heavy ions, however, can produce large complex DNA damages, which may lead to large deletions and are irreparable. For high-LET radiation, therefore, there are less or no dose rate effects. Physical shielding may not be effective in minimizing the biological effects on energetic heavy ions, since fragments of the primary particles can be effective in causing biological effects. At present the uncertainty of biological effects of heavy particles is still very large. With further understanding of the biological effects of space radiation, the career doses can be kept at acceptable levels so that the space radiation environment need not be a barrier to the exploitation of the promise of space.

  19. Space radiation parameters for EUI and the Sun Sensor of Solar Orbiter, ESIO, and JUDE instruments

    NASA Astrophysics Data System (ADS)

    Rossi, Laurence; Jacques, Lionel; Halain, Jean-Philippe; Renotte, Etienne; Thibert, Tanguy; Grodent, Denis

    2014-08-01

    This paper presents predictions of space radiation parameters for four space instruments performed by the Centre Spatial de Liège (ULg - Belgium); EUI, the Extreme Ultra-violet Instrument, on-board the Solar Orbiter platform; ESIO, Extreme-UV solar Imager for Operations, and JUDE, the Jupiter system Ultraviolet Dynamics Experiment, which was proposed for the JUICE platform. For Solar Orbiter platform, the radiation environment is defined by ESA environmental specification and the determination of the parameters is done through ray-trace analyses inside the EUI instrument. For ESIO instrument, the radiation environment of the geostationary orbit is defined through simulations of the trapped particles flux, the energetic solar protons flux and the galactic cosmic rays flux, taking the ECSS standard for space environment as a guideline. Then ray-trace analyses inside the instrument are performed to predict the particles fluxes at the level of the most radiation-sensitive elements of the instrument. For JUICE, the spacecraft trajectory is built from ephemeris files provided by ESA and the radiation environment is modeled through simulations by JOSE (Jovian Specification Environment model) then ray-trace analyses inside the instrument are performed to predict the particles fluxes at the level of the most radiation-sensitive elements of the instrument.

  20. Use of hematological parameters to assess the efficiency of quince (Cydonia oblonga Miller) leaf extract in alleviation of the effect of ultraviolet--A radiation on African catfish Clarias gariepinus (Burchell, 1822).

    PubMed

    Osman, Alaa G M; Koutb, Mostafa; Sayed, Alaa El-Din H

    2010-04-01

    The present study aimed to elucidate the negative impacts of UVA on some biochemical and hematological variables of the economically important African catfish, Clarias gariepinus and investigates the putative role of quince (Cydonia oblonga Miller) leaf extract in protection and/or alleviation of such negative impacts. Changes in the hematological and blood biochemical values often reflect alteration of physiological state. Blood parameters can be useful for the measurement of physiological disturbances in stressed fish and thus provide information about the level of damage in the fish. We found a significant (P<0.05) decrease in the red blood cell counts, hemoglobin and hematocrit in the groups exposed to UVA compared to the control groups. Exposure to UVA induced marked red cell shrinkage (increased mean cell hemoglobin concentration) and showed an elevation in mean cell volume and mean cell hemoglobin in the blood of the exposed fish compared to the control. A significant (P<0.05) reduction in the total white blood cells was recorded in the exposed fish compared to the control. The biochemical parameters (blood glucose, total plasma protein, blood cholesterol, plasma creatinine, aspartic amino transferase and alanine amino transferase) exhibited a significant increase in the blood of fish exposed to UVA. Methanolic extract of quince leaf before ripening of the fruits was analyzed by GC/MS. To investigate the biological impact of this extract and its biologically active components, this extract was tested for its putative role in alleviation of UVA effect on catfish. Quince leaf extract had the ability to prevent hematotoxic stress induced by UVA and resulted in enhancement of the immune system of catfish represented by significant (P<0.05) increase in the number of white blood cells and lymphocytes of the catfish. Quince extract also protected the red blood cells from UVA damage. To our knowledge this is the first report of the effect of quince leaf extract on

  1. Controlling the Radiation Parameters of a Resonant Medium Excited by a Sequence of Ultrashort Superluminal Pulses

    NASA Astrophysics Data System (ADS)

    Arkhipov, R. M.; Arkhipov, M. V.; Belov, P. A.; Babushkin, I.; Tolmachev, Yu. A.

    2016-03-01

    We investigate the possibility of controlling the radiation parameters of a spatially periodic one-dimensional medium consisting of classical harmonic oscillators by means of a sequence of ultrashort pulses that propagate through the medium with a superluminal velocity. We show that, in the spectrum of the transient process, in addition to the radiation at a resonant frequency of oscillators, new frequencies arise that depend on the period of the spatial distribution of the oscillator density, the excitation velocity, and the angle of observation. We have examined in detail the case of excitation of the medium by a periodic sequence of ultrashort pulses that travel with a superluminal velocity. We show that it is possible to excite oscillations of complex shapes and to control the radiation parameters of the resonant medium by changing the relationship between the pulse repetition rate, the medium resonant frequency, and the new frequency.

  2. Aging and Radiation Effects in Stockpile Electronics

    SciTech Connect

    Hartman, E.F.

    1999-03-25

    It is likely that aging is affecting the radiation hardness of stockpile electronics, and we have seen apparent examples of aging that affects the electronic radiation hardness. It is also possible that low-level intrinsic radiation that is inherent during stockpile life will damage or in a sense age electronic components. Both aging and low level radiation effects on radiation hardness and stockpile reliability need to be further investigated by using both test and modeling strategies that include appropriate testing of electronic components withdrawn from the stockpile.

  3. Retrieving high-resolution surface solar radiation with cloud parameters derived by combining MODIS and MTSAT data

    NASA Astrophysics Data System (ADS)

    Tang, W.; Qin, J.; Yang, K.; Liu, S.; Lu, N.; Niu, X.

    2015-12-01

    Cloud parameters (cloud mask, effective particle radius and liquid/ice water path) are the important inputs in determining surface solar radiation (SSR). These parameters can be derived from MODIS with high accuracy but their temporal resolution is too low to obtain high temporal resolution SSR retrievals. In order to obtain hourly cloud parameters, the Artificial Neural Network (ANN) is applied in this study to directly construct a functional relationship between MODIS cloud products and Multi-functional Transport Satellite (MTSAT) geostationary satellite signals. Meanwhile, an efficient parameterization model for SSR retrieval is introduced and, when driven with MODIS atmospheric and land products, its root mean square error (RMSE) is about 100 W m-2 for 44 Baseline Surface Radiation Network (BSRN) stations. Once the estimated cloud parameters and other information (such as aerosol, precipitable water, ozone and so on) are input to the model, we can derive SSR at high spatio-temporal resolution. The retrieved SSR is first evaluated against hourly radiation data at three experimental stations in the Haihe River Basin of China. The mean bias error (MBE) and RMSE in hourly SSR estimate are 12.0 W m-2 (or 3.5 %) and 98.5 W m-2 (or 28.9 %), respectively. The retrieved SSR is also evaluated against daily radiation data at 90 China Meteorological Administration (CMA) stations. The MBEs are 9.8 W m-2 (5.4 %); the RMSEs in daily and monthly-mean SSR estimates are 34.2 W m-2 (19.1 %) and 22.1 W m-2 (12.3 %), respectively. The accuracy is comparable or even higher than other two radiation products (GLASS and ISCCP-FD), and the present method is more computationally efficient and can produce hourly SSR data at a spatial resolution of 5 km.

  4. Retrieving high-resolution surface solar radiation with cloud parameters derived by combining MODIS and MTSAT data

    NASA Astrophysics Data System (ADS)

    Tang, Wenjun; Qin, Jun; Yang, Kun; Liu, Shaomin; Lu, Ning; Niu, Xiaolei

    2016-03-01

    Cloud parameters (cloud mask, effective particle radius, and liquid/ice water path) are the important inputs in estimating surface solar radiation (SSR). These parameters can be derived from MODIS with high accuracy, but their temporal resolution is too low to obtain high-temporal-resolution SSR retrievals. In order to obtain hourly cloud parameters, an artificial neural network (ANN) is applied in this study to directly construct a functional relationship between MODIS cloud products and Multifunctional Transport Satellite (MTSAT) geostationary satellite signals. In addition, an efficient parameterization model for SSR retrieval is introduced and, when driven with MODIS atmospheric and land products, its root mean square error (RMSE) is about 100 W m-2 for 44 Baseline Surface Radiation Network (BSRN) stations. Once the estimated cloud parameters and other information (such as aerosol, precipitable water, ozone) are input to the model, we can derive SSR at high spatiotemporal resolution. The retrieved SSR is first evaluated against hourly radiation data at three experimental stations in the Haihe River basin of China. The mean bias error (MBE) and RMSE in hourly SSR estimate are 12.0 W m-2 (or 3.5 %) and 98.5 W m-2 (or 28.9 %), respectively. The retrieved SSR is also evaluated against daily radiation data at 90 China Meteorological Administration (CMA) stations. The MBEs are 9.8 W m-2 (or 5.4 %); the RMSEs in daily and monthly mean SSR estimates are 34.2 W m-2 (or 19.1 %) and 22.1 W m-2 (or 12.3 %), respectively. The accuracy is comparable to or even higher than two other radiation products (GLASS and ISCCP-FD), and the present method is more computationally efficient and can produce hourly SSR data at a spatial resolution of 5 km.

  5. Some characteristics and effects of natural radiation.

    PubMed

    Mc Laughlin, J P

    2015-11-01

    Since life first appeared on the Earth, it has, in all its subsequent evolved forms including human, been exposed to natural radiation in the environment both from terrestrial and extra-terrestrial sources. Being an environmental mutagen, ionising natural radiation may have played a role of some significance in the evolution of early life forms on Earth. It has been estimated by United Nations Scientific Committee on the Effects of Atomic Radiation that at the present time, exposure to natural radiation globally results in an annual average individual effective dose of about 2.4 mSv. This represents about 80 % of the total dose from all sources. The three most important components of natural radiation exposure are cosmic radiation, terrestrial radioactivity and indoor radon. Each of these components exhibits both geographical and temporal variabilities with indoor radon exposure being the most variable and also the largest contributor to dose for most people. In this account, an overview is given of the characteristics of the main components of the natural radiation environment and some of their effects on humans. In the case of cosmic radiation, these range from radiation doses to aircrew and astronauts to the controversial topic of its possible effect on climate change. In the case of terrestrial natural radiation, accounts are given of a number of human exposure scenarios. PMID:25904693

  6. Effect of Burnishing Parameters on Surface Finish

    NASA Astrophysics Data System (ADS)

    Shirsat, Uddhav; Ahuja, Basant; Dhuttargaon, Mukund

    2016-06-01

    Burnishing is cold working process in which hard balls are pressed against the surface, resulting in improved surface finish. The surface gets compressed and then plasticized. This is a highly finishing process which is becoming more popular. Surface quality of the product improves its aesthetic appearance. The product made up of aluminum material is subjected to burnishing process during which kerosene is used as a lubricant. In this study factors affecting burnishing process such as burnishing force, speed, feed, work piece diameter and ball diameter are considered as input parameters while surface finish is considered as an output parameter In this study, experiments are designed using 25 factorial design in order to analyze the relationship between input and output parameters. The ANOVA technique and F-test are used for further analysis.

  7. Radiation Effects in Nuclear Waste Materials

    SciTech Connect

    William j. Weber; Lumin Wang; Jonathan Icenhower

    2004-07-09

    The objective of this project is to develop a fundamental understanding of radiation effects in glasses and ceramics, as well as the influence of solid-state radiation effects on aqueous dissolution kinetics, which may impact the performance of nuclear waste forms and stabilized nuclear materials.

  8. Dependence of erythemally weighted UV radiation on geographical parameters in the United States

    NASA Astrophysics Data System (ADS)

    Wang, Xinli; Gao, Wei; Davis, John; Olson, Becky; Janson, George; Slusser, James

    2007-09-01

    The relationship between solar ultraviolet (UV) radiation reaching the Earth's surface and geographical parameters is helpful in estimating the spatial distribution of UV radiation, which provides useful information to evaluate the potential impacts of enhanced UV levels on human health, agriculture, environment, and ecosystems for sustainable development. Measurements of erythemally weighted UV radiation at the sites of the United States Department of Agriculture UV-B Monitoring and Research Program (UVBMRP) monitoring network were analyzed to investigate the geographical distribution and seasonal variations. Twenty nine observation sites, which had continuous measurements during the recent six years, are selected for this study; twenty seven of them are distributed in the United States, including one in Hawaii and one in Alaska, and two of them are located in Canada along the United States border. The measurements were taken using the Yankee Environmental Systems Inc. (YES) UVB-1 ultraviolet pyranometer. This work focuses the data from the recent six years of 2001-2006 and the measurements during summer months (June-August) are emphasized. For each day, the measurements are integrated from sunrise to sunset to produce the daily UV dosage, which is then averaged for different seasons or for the whole year over the six years to generate the average daily UV dosage. A multivariable regression technique is exploited to characterize the dependence of UV dosages on geographical parameters, including latitude and altitude. The results show that, although there are many factors, such as clouds, ozone, aerosols, air pollutants, and haze, that affect the UV radiation intensity at a location, the latitude and altitude of the site are the primary factors that regulate the average daily UV dosage. On average over the last six years in the United States, more than 95% of the variability in averaged daily UV dosages can be explained by the latitude and altitude. Longitude is

  9. Hydrogenated amorphous silicon radiation detectors: Material parameters, radiation hardness, charge collection

    SciTech Connect

    Qureshi, S.

    1991-01-01

    For nearly two decades now hydrogenated amorphous silicon has generated considerable interest for its potential use in various device applications namely, solar cells, electrolithography, large-area electronics etc. The development of efficient and economic solar cells has been on the forefront of this research. This interest in hydrogenated amorphous silicon has been motivated by the fact that amorphous silicon can be deposited over a large area at relatively low cost compared to crystalline silicon. Hydrogenated amorphous silicon, frequently abbreviated as a-Si:H, used in solar-cell applications is a micron or less thick. The basic device structure is a p-i-n diode where the i layer is the active layer for radiation to interact. This is so because intrinsic a-Si:H has superior electrical properties in comparison to doped a-Si:H which serves the purpose of forming a potential barrier on either end of the i layer. The research presented in this dissertation was undertaken to study the properties of a-Si:H for radiation detection applications in physics and medicine.

  10. Overview of ICRP Committee 1: radiation effects.

    PubMed

    Morgan, W F

    2016-06-01

    This paper does not necessarily reflect the views of the International Commission on Radiological Protection. The author passed away on 13 November 2015.Committee 1 of the International Commission on Radiological Protection (ICRP) addresses issues pertinent to tissue reactions, risks of cancer and heritable diseases, radiation dose responses, effects of dose rate, and radiation quality. In addition, it reviews data on the effects of radiation on the embryo/fetus, genetic factors in radiation response, and uncertainties in providing judgements on radiation-induced health effects. Committee 1 advises the Main Commission on the biological basis of radiation-induced health effects, and how epidemiological, experimental, and theoretical data can be combined to make quantitative judgements on health risks to humans. The emphasis is on low radiation doses, in the form of detriment-adjusted nominal risk coefficients, where there are considerable uncertainties in terms of the biology and the epidemiology. Furthermore, Committee 1 reviews data from radiation epidemiology studies and publications on the molecular and cellular effects of ionising radiation relevant to updating the basis of the 2007 Recommendations published in ICRP Publication 103 This paper will provide an overview of the activities of Committee 1, the updated work of the Task Groups and Working Parties, and the future activities being pursued. PMID:26635336

  11. The biological effects of UVA radiation

    SciTech Connect

    Urbach, F.; Gange, R.

    1986-01-01

    Interest in the biological effects of longwave radiation has increased dramatically in the last few years. The contributors to this state of the art volume discuss the most current knowledge of biological effects of UVA and provide guidelines regarding acceptable human exposure to this type of radiation. Contents include: historical aspects of UVA effects; mechanisms of UVA photosensitization; photorecovery by UVA; photoaugmentation of UVB effects by UVA; effects of UVA radiation on tissues of the eye; new UVA sunscreen; and recommendations for future research and possible actions.

  12. Managing the adverse effects of radiation therapy.

    PubMed

    Berkey, Franklin J

    2010-08-15

    Nearly two thirds of patients with cancer will undergo radiation therapy as part of their treatment plan. Given the increased use of radiation therapy and the growing number of cancer survivors, family physicians will increasingly care for patients experiencing adverse effects of radiation. Selective serotonin reuptake inhibitors have been shown to significantly improve symptoms of depression in patients undergoing chemotherapy, although they have little effect on cancer-related fatigue. Radiation dermatitis is treated with topical steroids and emollient creams. Skin washing with a mild, unscented soap is acceptable. Cardiovascular disease is a well-established adverse effect in patients receiving radiation therapy, although there are no consensus recommendations for cardiovascular screening in this population. Radiation pneumonitis is treated with oral prednisone and pentoxifylline. Radiation esophagitis is treated with dietary modification, proton pump inhibitors, promotility agents, and viscous lidocaine. Radiation-induced emesis is ameliorated with 5-hydroxytryptamine3 receptor antagonists and steroids. Symptomatic treatments for chronic radiation cystitis include anticholinergic agents and phenazopyridine. Sexual dysfunction from radiation therapy includes erectile dysfunction and vaginal stenosis, which are treated with phosphodiesterase type 5 inhibitors and vaginal dilators, respectively. PMID:20704169

  13. Air Temperature estimation from Land Surface temperature and solar Radiation parameters

    NASA Astrophysics Data System (ADS)

    Lazzarini, Michele; Eissa, Yehia; Marpu, Prashanth; Ghedira, Hosni

    2013-04-01

    Air Temperature (AirT) is a fundamental parameter in a wide range of applications such as climate change studies, weather forecast, energy balance modeling, efficiency of Photovoltaic (PV) solar cells, etc. Air temperature data are generally obtained through regular measurements from meteorological stations. The distribution of these stations is normally sparse, so the spatial pattern of this parameter cannot be accurately estimated by interpolation methods. This work investigated the relationship between Air Temperature measured at meteorological stations and spatially contiguous measurements derived from Remote Sensing techniques, such as Land Surface Temperature (LST) maps, emissivity maps and shortwave radiation maps with the aim of creating a continuous map of AirT. For LST and emissivity, MSG-SEVIRI LST product from Land Surface Analysis Satellite Applications Facility (LSA-SAF) has been used. For shortwave radiation maps, an Artificial Neural Networks ensemble model has been developed and previously tested to create continuous maps from Global Horizontal Irradiance (GHI) point measurements, utilizing six thermal channels of MSG-SEVIRI. The testing sites corresponded to three meteorological stations located in the United Arab Emirates (UAE), where in situ measurements of Air Temperature were available. From the starting parameters, energy fluxes and net radiation have been calculated, in order to have information on the incoming and outgoing long-wave radiation and the incoming short-wave radiation. The preliminary analysis (day and Night measurements, cloud free) showed a strong negative correlation (0.92) between Outgoing long-wave radiation - GHI and LST- AirT, with a RMSE of 1.84 K in the AirT estimation from the initial parameters. Regression coefficients have been determined and tested on all the ground stations. The analysis also demonstrated the predominant impact of the incoming short-wave radiation in the AirT hourly variation, while the incoming

  14. Protective effects in radiation modification of elastomers

    NASA Astrophysics Data System (ADS)

    Głuszewski, Wojciech; Zagórski, Zbigniew P.; Rajkiewicz, Maria

    2014-12-01

    Saturated character of ethylene/octene thermoplastic elastomers demands an application of nonconventional methods of crosslinking connections between chains of molecules. These are organic peroxides, usually in the presence of coagents or an application of ionizing radiation. Several approaches (radiation, peroxide, peroxide/plus radiation and radiation/plus peroxide) were applied in crosslinking of elastomere Engage 8200. Attention was directed to the protection effects by aromatic peroxides and by photo- and thermostabilizers on radiolysis of elastomers. Role of dose of radiation, dose rate of radiation as well as the role of composition of elastomere on the radiation yield of hydrogen and absorbtion of oxygen was investigated. DRS method was used to follow postirradiation degradation. Influence of crosslinking methods on properties of elastomers is described. Results were interpreted from the point of view of protective actions of aromatic compounds.

  15. Effects of Radiation on Commercial Power Devices

    NASA Technical Reports Server (NTRS)

    Selva, Luis; Becker, Heidi; Chavez, Rosa; Scheick, Leif

    2006-01-01

    The effects of radiation on various commercial power devices are presented. The devices have proved to be very fragile to single event effects, with some of the devices actually succumbing to catastrophic SEE with protons.

  16. SOLAR RADIATION PRESSURE AND LOCAL INTERSTELLAR MEDIUM FLOW PARAMETERS FROM INTERSTELLAR BOUNDARY EXPLORER LOW ENERGY HYDROGEN MEASUREMENTS

    SciTech Connect

    Schwadron, N. A.; Moebius, E.; Kucharek, H.; Lee, M. A.; French, J.; Saul, L.; Wurz, P.; Bzowski, M.; Fuselier, S. A.; Livadiotis, G.; McComas, D. J.; Frisch, P.; Gruntman, M.; Mueller, H. R.

    2013-10-01

    Neutral hydrogen atoms that travel into the heliosphere from the local interstellar medium (LISM) experience strong effects due to charge exchange and radiation pressure from resonant absorption and re-emission of Lyα. The radiation pressure roughly compensates for the solar gravity. As a result, interstellar hydrogen atoms move along trajectories that are quite different than those of heavier interstellar species such as helium and oxygen, which experience relatively weak radiation pressure. Charge exchange leads to the loss of primary neutrals from the LISM and the addition of new secondary neutrals from the heliosheath. IBEX observations show clear effects of radiation pressure in a large longitudinal shift in the peak of interstellar hydrogen compared with that of interstellar helium. Here, we compare results from the Lee et al. interstellar neutral model with IBEX-Lo hydrogen observations to describe the distribution of hydrogen near 1 AU and provide new estimates of the solar radiation pressure. We find over the period analyzed from 2009 to 2011 that radiation pressure divided by the gravitational force (μ) has increased slightly from μ = 0.94 ± 0.04 in 2009 to μ = 1.01 ± 0.05 in 2011. We have also derived the speed, temperature, source longitude, and latitude of the neutral H atoms and find that these parameters are roughly consistent with those of interstellar He, particularly when considering the filtration effects that act on H in the outer heliosheath. Thus, our analysis shows that over the period from 2009 to 2011, we observe signatures of neutral H consistent with the primary distribution of atoms from the LISM and a radiation pressure that increases in the early rise of solar activity.

  17. Physics of intense, high energy radiation effects.

    SciTech Connect

    Hjalmarson, Harold Paul; Hartman, E. Frederick; Magyar, Rudolph J.; Crozier, Paul Stewart

    2011-02-01

    This document summarizes the work done in our three-year LDRD project titled 'Physics of Intense, High Energy Radiation Effects.' This LDRD is focused on electrical effects of ionizing radiation at high dose-rates. One major thrust throughout the project has been the radiation-induced conductivity (RIC) produced by the ionizing radiation. Another important consideration has been the electrical effect of dose-enhanced radiation. This transient effect can produce an electromagnetic pulse (EMP). The unifying theme of the project has been the dielectric function. This quantity contains much of the physics covered in this project. For example, the work on transient electrical effects in radiation-induced conductivity (RIC) has been a key focus for the work on the EMP effects. This physics in contained in the dielectric function, which can also be expressed as a conductivity. The transient defects created during a radiation event are also contained, in principle. The energy loss lead the hot electrons and holes is given by the stopping power of ionizing radiation. This information is given by the inverse dielectric function. Finally, the short time atomistic phenomena caused by ionizing radiation can also be considered to be contained within the dielectric function. During the LDRD, meetings about the work were held every week. These discussions involved theorists, experimentalists and engineers. These discussions branched out into the work done in other projects. For example, the work on EMP effects had influence on another project focused on such phenomena in gases. Furthermore, the physics of radiation detectors and radiation dosimeters was often discussed, and these discussions had impact on related projects. Some LDRD-related documents are now stored on a sharepoint site (https://sharepoint.sandia.gov/sites/LDRD-REMS/default.aspx). In the remainder of this document the work is described in catergories but there is much overlap between the atomistic calculations, the

  18. Radiation Pneumonitis After Hypofractionated Radiotherapy: Evaluation of the LQ(L) Model and Different Dose Parameters

    SciTech Connect

    Borst, Gerben R.; Ishikawa, Masayori; Nijkamp, Jasper

    2010-08-01

    Purpose: To evaluate the linear quadratic (LQ) model for hypofractionated radiotherapy within the context of predicting radiation pneumonitis (RP) and to investigate the effect if a linear (L) model in the high region (LQL model) is used. Methods and Materials: The radiation doses used for 128 patients treated with hypofractionated radiotherapy were converted to the equivalent doses given in fractions of 2 Gy for a range of {alpha}/{beta} ratios (1 Gy to infinity) according to the LQ(L) model. For the LQL model, different cut-off values between the LQ model and the linear component were used. The Lyman model parameters were fitted to the events of RP grade 2 or higher to derive the normal tissue complication probability (NTCP). The lung dose was calculated as the mean lung dose and the percentage of lung volume (V) receiving doses higher than a threshold dose of xGy (V{sub x}). Results: The best NTCP fit was found if the mean lung dose, or V{sub x}, was calculated with an {alpha}/{beta} ratio of 3 Gy. The NTCP fit of other {alpha}/{beta} ratios and the LQL model were worse but within the 95% confidence interval of the NTCP fit of the LQ model with an {alpha}/{beta} ratio of 3 Gy. The V{sub 50} NTCP fit was better than the NTCP fit of lower threshold doses. Conclusions: For high fraction doses, the LQ model with an {alpha}/{beta} ratio of 3 Gy was the best method for converting the physical lung dose to predict RP.

  19. Radiation effects in optoelectronic devices. [Review

    SciTech Connect

    Barnes, C.E.; Wiczer, J.J.

    1984-05-01

    Purpose of this report is to provide not only a summary of radiation damage studies at Sandia National Laboratories, but also of those in the literature on the components of optoelectronic systems: light emitting diodes (LEDs), laser diodes, photodetectors, optical fibers, and optical isolators. This review of radiation damage in optoelectronic components is structured according to device type. In each section, a brief discussion of those device properties relevant to radiation effects is given.

  20. Radiation damage effects on solid state detectors

    NASA Technical Reports Server (NTRS)

    Trainor, J. H.

    1972-01-01

    Totally depleted silicon diodes are discussed which are used as nuclear particle detectors in investigations of galactic and solar cosmic radiation and trapped radiation. A study of radiation and chemical effects on the diodes was conducted. Work on electron and proton irradiation of surface barrier detectors with thicknesses up to 1 mm was completed, and work on lithium-drifted silicon devices with thicknesses of several millimeters was begun.

  1. Comprehensive Evaluation of Personal, Clinical, and Radiation Dosimetric Parameters for Acute Skin Reaction during Whole Breast Radiotherapy

    PubMed Central

    Yang, Dae Sik; Lee, Jung Ae; Lee, Nam Kwon; Park, Young Je; Lee, Suk; Kim, Chul Yong; Son, Gil Soo

    2016-01-01

    Skin reaction is major problem during whole breast radiotherapy. To identify factors related to skin reactions during whole breast radiotherapy, various personal, clinical, and radiation dosimetric parameters were evaluated. From January 2012 to December 2013, a total of 125 patients who underwent breast conserving surgery and adjuvant whole breast irradiation were retrospectively reviewed. All patients had both whole breast irradiation and boost to the tumour bed. Skin reaction was measured on the first day of boost therapy based on photography of the radiation field and medical records. For each area of axilla and inferior fold, the intensity score of erythema (score 1 to 5) and extent (score 0 to 1) were summed. The relationship of various parameters to skin reaction was evaluated using chi-square and linear regression tests. The V100 (volume receiving 100% of prescribed radiation dose, p < 0.001, both axilla and inferior fold) and age (p = 0.039 for axilla and 0.026 for inferior fold) were significant parameters in multivariate analyses. The calculated axilla dose (p = 0.003) and breast separation (p = 0.036) were also risk factors for axilla and inferior fold, respectively. Young age and large V100 are significant factors for acute skin reaction that can be simply and cost-effectively measured. PMID:27579310

  2. Comprehensive Evaluation of Personal, Clinical, and Radiation Dosimetric Parameters for Acute Skin Reaction during Whole Breast Radiotherapy.

    PubMed

    Yang, Dae Sik; Lee, Jung Ae; Yoon, Won Sup; Lee, Nam Kwon; Park, Young Je; Lee, Suk; Kim, Chul Yong; Son, Gil Soo

    2016-01-01

    Skin reaction is major problem during whole breast radiotherapy. To identify factors related to skin reactions during whole breast radiotherapy, various personal, clinical, and radiation dosimetric parameters were evaluated. From January 2012 to December 2013, a total of 125 patients who underwent breast conserving surgery and adjuvant whole breast irradiation were retrospectively reviewed. All patients had both whole breast irradiation and boost to the tumour bed. Skin reaction was measured on the first day of boost therapy based on photography of the radiation field and medical records. For each area of axilla and inferior fold, the intensity score of erythema (score 1 to 5) and extent (score 0 to 1) were summed. The relationship of various parameters to skin reaction was evaluated using chi-square and linear regression tests. The V 100 (volume receiving 100% of prescribed radiation dose, p < 0.001, both axilla and inferior fold) and age (p = 0.039 for axilla and 0.026 for inferior fold) were significant parameters in multivariate analyses. The calculated axilla dose (p = 0.003) and breast separation (p = 0.036) were also risk factors for axilla and inferior fold, respectively. Young age and large V 100 are significant factors for acute skin reaction that can be simply and cost-effectively measured. PMID:27579310

  3. IONIZATION PARAMETER AS A DIAGNOSTIC OF RADIATION AND WIND PRESSURES IN H II REGIONS AND STARBURST GALAXIES

    SciTech Connect

    Yeh, Sherry C. C.; Matzner, Christopher D.

    2012-10-01

    The ionization parameter U is potentially useful as a tool to measure radiation pressure feedback from massive star clusters, as it directly reflects the ratio of radiation to gas pressure and is readily derived from mid-infrared line ratios. We consider a number of physical effects which combine to determine the apparent value of U in observations encompassing one or many H II regions. An upper limit is set by the compression of gas by radiation pressure, when this is important. The pressure of shocked stellar winds and the presence of neutral clumps both tend to reduce U for a given intensity of irradiation. The most intensely irradiated regions are selectively dimmed by internal dust absorption of ionizing photons, leading to a bias for observations on galactic scales. We explore these effects in analytical and numerical models for dusty H II regions and use them to interpret previous observational results. We find that radiation pressure confinement sets the upper limit log{sub 10}U{approx_equal}-1 seen in individual regions. Unresolved starbursts are known to display a maximum value of {approx_equal} - 2.3. While lower, this is also consistent with a large portion of their H II regions being radiation pressure dominated, given the different technique used to interpret unresolved regions, and given the bias caused by dust absorption. We infer that many individual, strongly illuminated regions cannot be significantly overpressured by stellar winds, and that even when averaged on galactic scales, the shocked wind pressure cannot be large compared to radiation pressure. Therefore, most H II regions cannot be adiabatic wind bubbles. Our models imply a metallicity dependence in the physical structure and dust attenuation of radiation-dominated regions, both of which should vary strongly across a critical metallicity of about one-twentieth solar.

  4. Ionization Parameter as a Diagnostic of Radiation and Wind Pressures in H II Regions and Starburst Galaxies

    NASA Astrophysics Data System (ADS)

    Yeh, Sherry C. C.; Matzner, Christopher D.

    2012-10-01

    The ionization parameter {\\cal U} is potentially useful as a tool to measure radiation pressure feedback from massive star clusters, as it directly reflects the ratio of radiation to gas pressure and is readily derived from mid-infrared line ratios. We consider a number of physical effects which combine to determine the apparent value of {\\cal U} in observations encompassing one or many H II regions. An upper limit is set by the compression of gas by radiation pressure, when this is important. The pressure of shocked stellar winds and the presence of neutral clumps both tend to reduce {\\cal U} for a given intensity of irradiation. The most intensely irradiated regions are selectively dimmed by internal dust absorption of ionizing photons, leading to a bias for observations on galactic scales. We explore these effects in analytical and numerical models for dusty H II regions and use them to interpret previous observational results. We find that radiation pressure confinement sets the upper limit log _{10} {\\cal U}\\simeq -1 seen in individual regions. Unresolved starbursts are known to display a maximum value of ~= - 2.3. While lower, this is also consistent with a large portion of their H II regions being radiation pressure dominated, given the different technique used to interpret unresolved regions, and given the bias caused by dust absorption. We infer that many individual, strongly illuminated regions cannot be significantly overpressured by stellar winds, and that even when averaged on galactic scales, the shocked wind pressure cannot be large compared to radiation pressure. Therefore, most H II regions cannot be adiabatic wind bubbles. Our models imply a metallicity dependence in the physical structure and dust attenuation of radiation-dominated regions, both of which should vary strongly across a critical metallicity of about one-twentieth solar.

  5. Tidal radiation. [relativistic gravitational effects

    NASA Technical Reports Server (NTRS)

    Mashhoon, B.

    1977-01-01

    The general theory of tides is developed within the framework of Einstein's theory of gravitation. It is based on the concept of Fermi frame and the associated notion of tidal frame along an open curve in spacetime. Following the previous work of the author an approximate scheme for the evaluation of tidal gravitational radiation is presented which is valid for weak gravitational fields. The emission of gravitational radiation from a body in the field of a black hole is discussed, and for some cases of astrophysical interest estimates are given for the contributions of radiation due to center-of-mass motion, purely tidal deformation, and the interference between the center of mass and tidal motions.

  6. Variability and trend of mean cloud parameters and outgoing longwave radiation determined by satellite sounders

    NASA Astrophysics Data System (ADS)

    Molnar, G. I.; Susskind, J.

    2005-12-01

    Global energy balance of the Earth-atmosphere system may change due to natural and man-made climate variations. For example, changes in the outgoing longwave radiation (OLR) can be regarded as a crucial indicator of climate variations. Clouds play an important role -still insufficiently assessed-, in the global energy balance on all spatial and temporal scales, and satellites can provide an ideal platform to measure cloud and large-scale atmospheric variables simultaneously. This is extremely important for developing more reliable cloud models, which could help to improve the representation of cloud-climate feedbacks (probably the least known ones, still hindering global warming predictions, for example) in global general circulation models. The TOVS series of satellites were the first to provide this type of information since 1979 on. OLR [Mehta and Susskind, 1999], cloud cover and cloud top pressure [Susskind et al., 1997] are among the key climatic parameters computed by the TOVS Path A algorithm using mainly the retrieved temperature and moisture profiles. Here we present validation efforts and preliminary trend analyses of TOVS-retrieved cloud top pressures [Pc] and "effective" (Aeff, a product of infrared emissivity at 11 μm and physical cloud cover or Ac) cloud fractions. For example, the TOVS and ISCCP [available since 1983] cloud top pressures correlate strongly. Decadal trends in Pc and Aeff/Ac are also similar. However, validation of the TOVS Aeff time series requires further effort, since the ISCCP provides the Ac time series only. We are also presenting encouraging agreements between MODIS and AIRS [which can be regarded as the "new and improved TOVS"] Pc and Aeff interannual variabilities for selected Months. We also present TOVS and AIRS OLR validation effort results and (for the longer-term TOVS) trend analyses. OLR interannual spatial variabilities from the available state-of-the-art CERES measurements and both from the AIRS [Susskind et al., 2003

  7. Flare loop radiative hydrodynamics. III - Nonlocal radiative transfer effects

    NASA Technical Reports Server (NTRS)

    Canfield, R. C.; Fisher, G. H.; Mcclymont, A. N.

    1983-01-01

    The study has three goals. The first is to demonstrate that processes exist whose intrinsic nonlocal nature cannot be represented by local approximations. The second is to elucidate the physical nature and origins of these nonlocal processes. The third is to suggest that the methods and results described here may prove useful in constructing semiempirical models of the chromosphere by means more efficient than trial and error. Matrices are computed that describe the effect of a temperature perturbation at an arbitrary point in the loop on density, hydrogen ionized fraction, total radiative loss rate, and radiative loss rate of selected hydrogen lines and continua at all other points. It is found that the dominant nonlocal radiative transfer effects can be separated into flux divergence coefficient effects and upper level population effects. The former are most important when the perturbation takes place in a region of significant opacity. Upper level population effects arise in both optically thick and thin regions in response to nonlocal density, ionization, and interlocking effects.

  8. Effect of gamma radiation on honey quality control

    NASA Astrophysics Data System (ADS)

    Bera, A.; Almeida-Muradian, L. B.; Sabato, S. F.

    2009-07-01

    Honey is one of the most complex substances produced by bees, mainly from the nectar of flowers. Gamma radiation is a technique that can be used to decrease the number of microbiological problems associated with food and increase the shelf life of certain products. The objective of this study was to verify the effect of gamma radiation with source of cobalto-60 (10 kGy) on some parameters used in honey quality control. Seven samples of pure honey were obtained from local markets in Sao Paulo, Brazil, in 2007. The methods used are in accordance with Brazilian Regulations. The physicochemical parameters analyzed were: moisture, HMF, free acidity, pH, sugars and ash. The results showed that gamma radiation, in the dose mentioned above, did not cause significant physicochemical alterations.

  9. Evaluation and optimization of the structural parameter of diesel nozzle basing on synchrotron radiation imaging techniques

    NASA Astrophysics Data System (ADS)

    Wu, Z.; Gao, Y.; Gong, H.; Li, L.

    2016-04-01

    Lacking of efficient methods, industry currently uses one only parameter—fuel flow rate—to evaluate the nozzle quality, which is far from satisfying the current emission regulations worldwide. By utilizing synchrotron radiation high energy X-ray in Shanghai Synchrotron Radiation Facility (SSRF), together with the imaging techniques, the 3D models of two nozzles with the same design dimensions were established, and the influence of parameters fluctuation in the azimuthal direction were analyzed in detail. Results indicate that, due to the orifice misalignment, even with the same design dimension, the inlet rounding radius of orifices differs greatly, and its fluctuation in azimuthal direction is also large. This difference will cause variation in the flow characteristics at orifice outlet and then further affect the spray characteristics. The study also indicates that, more precise investigation and insight into the evaluation and optimization of diesel nozzle structural parameter are needed.

  10. Overview of radiation effects research in photonics

    NASA Astrophysics Data System (ADS)

    Webb, Robert C.; Cohn, Lewis M.; Taylor, Edward W.; Greenwell, Roger A.

    1995-05-01

    A brief overview of ongoing radiation effects research in photonics is presented focusing on integrated optic and acousto-optic components. A short summary of radiation-induced effects in electro-optic modulators, detector arrays, and other photonic technologies is presented along with extensive references. The coordinated radiation effects studies among researchers within the Tri-Service Organizations and international experimental teams are beginning to demonstrate consistent measurements of radiation-induced effects in photonic components and confirming earlier reported data. This paper will present an overview of these coordinated investigations and focus on key research being conducted with the AFMC Phillips Laboratory, Naval Research Laboratory, Defence Nuclear Agency, NATO Nuclear Effects Task Group, and the Tri-Service Photonics Coordinating Committee.

  11. Measures of GCM Performance as Functions of Model Parameters Affecting Clouds and Radiation

    NASA Astrophysics Data System (ADS)

    Jackson, C.; Mu, Q.; Sen, M.; Stoffa, P.

    2002-05-01

    This abstract is one of three related presentations at this meeting dealing with several issues surrounding optimal parameter and uncertainty estimation of model predictions of climate. Uncertainty in model predictions of climate depends in part on the uncertainty produced by model approximations or parameterizations of unresolved physics. Evaluating these uncertainties is computationally expensive because one needs to evaluate how arbitrary choices for any given combination of model parameters affects model performance. Because the computational effort grows exponentially with the number of parameters being investigated, it is important to choose parameters carefully. Evaluating whether a parameter is worth investigating depends on two considerations: 1) does reasonable choices of parameter values produce a large range in model response relative to observational uncertainty? and 2) does the model response depend non-linearly on various combinations of model parameters? We have decided to narrow our attention to selecting parameters that affect clouds and radiation, as it is likely that these parameters will dominate uncertainties in model predictions of future climate. We present preliminary results of ~20 to 30 AMIPII style climate model integrations using NCAR's CCM3.10 that show model performance as functions of individual parameters controlling 1) critical relative humidity for cloud formation (RHMIN), and 2) boundary layer critical Richardson number (RICR). We also explore various definitions of model performance that include some or all observational data sources (surface air temperature and pressure, meridional and zonal winds, clouds, long and short-wave cloud forcings, etc...) and evaluate in a few select cases whether the model's response depends non-linearly on the parameter values we have selected.

  12. Radiation Effect on Human Tissue

    NASA Technical Reports Server (NTRS)

    Richmond, Robert C.; Cruz, Angela; Bors, Karen; Curreri, Peter A. (Technical Monitor)

    2002-01-01

    Predicting the occurrence of human cancer following exposure of an epidemiologic population to any agent causing genetic damage is a difficult task. To an approximation, this is because the uncertainty of uniform exposure to the damaging agent, and the uncertainty of uniform processing of that damage within a complex set of biological variables, degrade the confidence of predicting the delayed expression of cancer as a relatively rare event within clinically normal individuals. This situation begs the need for alternate controlled experimental models that are predictive for the development of human cancer following exposures to agents causing genetic damage. Such models historically have not been of substantial proven value. It is more recently encouraging, however, that developments in molecular and cell biology have led to an expanded knowledge of human carcinogenesis, and of molecular markers associated with that process. It is therefore appropriate to consider new laboratory models developed to accomodate that expanded knowledge in order to assess the cancer risks associated with exposures to genotoxic agents. When ionizing radiation of space is the genotoxic agent, then a series of additional considerations for human cancer risk assessment must also be applied. These include the dose of radiation absorbed by tissue at different locations in the body, the quality of the absorbed radiation, the rate at which absorbed dose accumulates in tissue, the way in which absorbed dose is measured and calculated, and the alterations in incident radiation caused by shielding materials. It is clear that human cancer risk assessment for damage caused by ionizing radiation is a multidisciplinary responsibility, and that within this responsibility no single discipline can hold disproportionate sway if a risk assessment model of radiation-induced human cancer is to be developed that has proven value. Biomolecular and cellular markers from the work reported here are considered

  13. Radiation effects in the lung.

    PubMed Central

    Coggle, J E; Lambert, B E; Moores, S R

    1986-01-01

    This article outlines the principles of radiobiology that can explain the time of onset, duration, and severity of the complex reactions of the lung to ionizing radiation. These reactions have been assayed biochemically, cell kinetically, physiologically, and pathologically. Clinical and experimental data are used to describe the acute and late reactions of the lung to both external and internal radiation including pneumonitis, fibrosis and carcinogenesis. Acute radiation pneumonitis, which can be fatal, develops in both humans and animals within 6 months of exposure to doses greater than or equal to 8 Gy of low LET radiation. It is divisible into a latent period lasting up to 4 weeks; an exudative phase (3-8 weeks) and with an acute pneumonitic phase between 2 and 6 months. The latter is an inflammatory reaction with intra-alveolar and septal edema accompanied by epithelial and endothelial desquamation. The critical role of type II pneumonocytes is discussed. One favored hypothesis suggests that the primary response of the lung is an increase in microvascular permeability. The plasma proteins overwhelm the lymphatic and other drainage mechanisms and this elicits the secondary response of type II cell hyperplasia. This, in its turn, produces an excess of surfactant that ultimately causes the fall in compliance, abnormal gas exchange values, and even respiratory failure. The inflammatory early reaction may progress to chronic fibrosis. There is much evidence to suggest that pneumonitis is an epithelial reaction and some evidence to suggest that this early damage may not be predictive of late fibrosis. However, despite detailed work on collagen metabolism, the pathogenesis of radiation fibrosis remains unknown. The data on radiation-induced pulmonary cancer, both in man and experimental animals from both external and internal irradiation following the inhalation of both soluble and insoluble alpha and beta emitting radionuclides are reviewed. Emphasis is placed on

  14. Neutron flux spectra and radiation damage parameters for the Russian Bor-60 and SM-2 reactors

    SciTech Connect

    Karasiov, A.V.; Greenwood, L.R.

    1995-04-01

    The objective is to compare neutron irradiation conditions in Russian reactors and similar US facilities. Neutron fluence and spectral information and calculated radiation damage parameters are presented for the BOR-60 (Fast Experimental Reactor - 60 MW) and SM-2 reactors in Russia. Their neutron exposure characteristics are comparable with those of the Experimental Breeder Reactor (ERB-II), the Fast Flux Test Facility (FFTF), and the High Flux Isotope Reactor (HFIR) in the United States.

  15. Effects of radiation therapy in microvascular anastomoses

    SciTech Connect

    Fried, M.P.

    1985-07-01

    The otolaryngologist, as a head and neck surgeon, commonly cares for patients with upper aerodigestive tract malignancies. Therapy of these neoplasms often requires wide excision. One standard reconstructive procedure utilizes pedicled regional flaps, both dermal and myodermal which have some disadvantages. The shortcomings of these pedicled regional flaps have led to the use of the vascularized free flap in certain cases. The occasional case may lead to catastrophe if microanastomoses fail when combined with radiation. Notwithstanding, many surgical series have reported success when radiation has been given. The present investigation was undertaken to assess the effects of radiation therapy on microvascular anastomoses when radiation is administered pre- or postoperatively or when nonradiated tissue is transferred to an irradiated recipient site. These effects were observed serially in an experimental rat model using a tubed superficial epigastric flap that adequately reflected tissue viability and vascular patency. The histologic changes were then noted over a three month period after completion of both radiation and surgery. This study adds credence to the observation of the lack of deleterious effects of radiation on experimental microvascular anastomotic patency whether the radiation is given before or after surgery or if radiated tissue is approximated to nonradiated vessels.

  16. Influence of gamma radiation on microbiological parameters of the ethanolic fermentation of sugar-cane must

    NASA Astrophysics Data System (ADS)

    Alcarde, A. R.; Walder, J. M. M.; Horii, J.

    2003-04-01

    The influence of gamma radiation on reducing the population of some bacteria Bacillus and Lactobacillus that usually contaminate the sugar-cane must and its effects on acidity of the medium and viability of the yeast during fermentation were evaluated. The treatment with gamma radiation reduced the bacterial load of the sugar-cane must. Consequently, the volatile acidity produced during the fermentation of the must decreased and the viability of the yeast afterwards added increased.

  17. Effect of radiative heat transfer on the convective stability of a fluid in a slot

    NASA Astrophysics Data System (ADS)

    Kural, O.

    1988-06-01

    A fluid, confined between two vertical flat plates, with a linear temperature gradient decreasing upwards, is investigated analytically for convective stability under the influence of radiative heat transfer. The effect of radiative transfer is accounted for by use of the Milne-Eddington differential approximation. It is shown that three dimensionless parameters influence the stability: the optical thickness, tau, a parameter A which compares radiative and conductive fluxes, and E, which combines the effects of boundary surface properties with the 'color' properties of the medium. It is shown that radiative heat transfer has a stabilizing effect on the system and that A and tau exert strong influences.

  18. Effects of solar radiation on glass

    NASA Technical Reports Server (NTRS)

    Tucker, Dennis S.; Kinser, Donald L.

    1991-01-01

    The effects of solar radiation of selected glasses are reported. Optical property degradation is studied using UV-Vis spectrophotometry. Strength changes are measured using a concentric ring bend test. Direct fracture toughness measurements using an indentation test are planned.

  19. RADIATION EFFECTS IN NUCLEAR WASTE MATERIALS

    EPA Science Inventory

    The objective of this multidisciplinary, multi-institutional research effort is to develop a fundamental understanding at the atomic, microscopic, and macroscopic levels of radiation effects in glass and ceramics that provides the underpinning science and models for evaluation an...

  20. Assurance Against Radiation Effects on Electronics

    NASA Technical Reports Server (NTRS)

    LaBel, Kenneth A.

    2004-01-01

    Contents include the following: The Space Radiation Environment. The Effects on Electronics. The Environment in Action. NASA Approaches to Commercial Electronics: the mission mix, flight projects, and proactive research. Final Thoughts: atomic interactions, direct ionization, interaction with nucleus.

  1. Perturbed effects at radiation physics

    NASA Astrophysics Data System (ADS)

    Külahcı, Fatih; Şen, Zekâi

    2013-09-01

    Perturbation methodology is applied in order to assess the linear attenuation coefficient, mass attenuation coefficient and cross-section behavior with random components in the basic variables such as the radiation amounts frequently used in the radiation physics and chemistry. Additionally, layer attenuation coefficient (LAC) and perturbed LAC (PLAC) are proposed for different contact materials. Perturbation methodology provides opportunity to obtain results with random deviations from the average behavior of each variable that enters the whole mathematical expression. The basic photon intensity variation expression as the inverse exponential power law (as Beer-Lambert's law) is adopted for perturbation method exposition. Perturbed results are presented not only in terms of the mean but additionally the standard deviation and the correlation coefficients. Such perturbation expressions provide one to assess small random variability in basic variables.

  2. The Effects of Ionizing Radiation on Mammalian Cells.

    ERIC Educational Resources Information Center

    Biaglow, John E.

    1981-01-01

    Discusses the effects of radiation on dividing cells and factors influencing these effects; also briefly reviews the radical mechanism for radiation damage. Emphasizes the importance of oxygen in radiation effects. (CS)

  3. Radiative effects of global MODIS cloud regimes

    NASA Astrophysics Data System (ADS)

    Oreopoulos, Lazaros; Cho, Nayeong; Lee, Dongmin; Kato, Seiji

    2016-03-01

    We update previously published Moderate Resolution Imaging Spectroradiometer (MODIS) global cloud regimes (CRs) using the latest MODIS cloud retrievals in the Collection 6 data set. We implement a slightly different derivation method, investigate the composition of the regimes, and then proceed to examine several aspects of CR radiative appearance with the aid of various radiative flux data sets. Our results clearly show that the CRs are radiatively distinct in terms of shortwave, longwave, and their combined (total) cloud radiative effect. We show that we can clearly distinguish regimes based on whether they radiatively cool or warm the atmosphere, and thanks to radiative heating profiles, to discern the vertical distribution of cooling and warming. Terra and Aqua comparisons provide information about the degree to which morning and afternoon occurrences of regimes affect the symmetry of CR radiative contribution. We examine how the radiative discrepancies among multiple irradiance data sets suffering from imperfect spatiotemporal matching depend on CR and whether they are therefore related to the complexity of cloud structure, its interpretation by different observational systems, and its subsequent representation in radiative transfer calculations.

  4. Fast Neutron Radiation Effects on Bacillus Subtili

    NASA Astrophysics Data System (ADS)

    Chen, Xiaoming; Ren, Zhenglong; Zhang, Jianguo; Zheng, Chun; Tan, Bisheng; Yang, Chengde; Chu, Shijin

    2009-06-01

    To examine the sterilizing effect and mechanism of neutron radiation, Bacillus subtilis var. niger. strain (ATCC 9372) spores were irradiated with the fast neutron from the Chinese fast burst reactor II(CFBR-II). The plate-count results indicated that the D10 value was 384.6 Gy with a neutron radiation dose rate of 7.4 Gy/min. The rudimental catalase activity of the spores declined obviously with the increase in the radiation dose. Meanwhile, under the scanning electron microscope, no visible influence of the neutron radiation on the spore configuration was detected even if the dose was increased to 4 kGy. The content and distribution of DNA double-strand breaks induced by neutron radiation at different doses were measured and quantified by pulsed-field gel electrophoresis (PFGE). Further analysis of the DNA release percentage (PR), the DNA breakage level (L), and the average molecular weight, indicated that DNA fragments were obviously distributed around the 5 kb regions at different radiation doses, which suggests that some points in the DNA molecule were sensitive to neutron radiation. Both PR and L varied regularly to some extent with the increase in radiation dose. Thus neutron radiation has a high sterilization power, and can induce falling enzyme activity and DNA breakage in Bacillus subtilis spores

  5. Radiation effects on polymeric materials

    NASA Technical Reports Server (NTRS)

    Kiefer, Richard L.

    1988-01-01

    It is important to study changes in properties of polymeres after irradiation with charged particles, with ultraviolet radiation, and with combinations of both. An apparatus for this purpose has been built at the NASA Langley Research Center. It consists of a chamber 9 inches in diameter and 9 inches high with a port for an electron gun, another port for a mass spectrometer, and a quartz window through which an ultraviolet lamp can be focused. The chamber, including the electron gun and the mass spectrometer, can be evacuated to a pressure of 10 to the 8th power torr. A sample placed in the chamber can be irradiated with electrons and ultraviolet radiation separately, sequentially, or simultaneously, while volatile products can be monitored during all irradiations with the mass spectrometer. The apparatus described above has been used to study three different polymer films: lexan; a polycarbonate; P1700, a polysulfone; and mylar, a polyethylene terephthalate. All three polymers had been studied extensively with both electrons and ultraviolet radiation separately, but not simultaneously. Also, volatile products had not been monitored during irradiation for the materials. A high electron dose rate of 530 Mrads/hr was used so that a sufficient concentration of volatile products would be formed to yield a reasonable mass spectrum.

  6. Cloud effects on middle ultraviolet global radiation

    NASA Technical Reports Server (NTRS)

    Borkowski, J.; Chai, A.-T.; Mo, T.; Green, A. E. O.

    1977-01-01

    An Eppley radiometer and a Robertson-Berger sunburn meter are employed along with an all-sky camera setup to study cloud effects on middle ultraviolet global radiation at the ground level. Semiempirical equations to allow for cloud effects presented in previous work are compared with the experimental data. The study suggests a means of defining eigenvectors of cloud patterns and correlating them with the radiation at the ground level.

  7. Coherent Radiation Effects in the LCLS Undulator

    SciTech Connect

    Reiche, S.; Huang, Z.; /SLAC

    2010-12-14

    For X-ray Free-Electron Lasers such as LCLS and TESLA FEL, a change in the electron energy while amplifying the FEL radiation can shift the resonance condition out of the bandwidth of the FEL. The largest sources of energy loss is the emission of incoherent undulator radiation. Because the loss per electron depends only on the undulator parameters and the beam energy, which are fixed for a given resonant wavelength, the average energy loss can be compensated for by a fixed taper of the undulator. Coherent radiation has a strong enhancement proportional to the number of electrons in the bunch for frequencies comparable to or longer than the bunch dimension. If the emitted coherent energy becomes comparable to that of the incoherent emission, it has to be included in the taper as well. However, the coherent loss depends on the bunch charge and the applied compression scheme and a change of these parameters would require a change of the taper. This imposes a limitation on the practical operation of Free-Electron Lasers, where the taper can only be adjusted manually. In this presentation we analyze the coherent emission of undulator radiation and transition undulator radiation for LCLS, and estimate whether the resulting energy losses are significant for the operation of LCLS.

  8. Effect-specific analysis of propagation parameters

    NASA Technical Reports Server (NTRS)

    Ortgies, G.; Ruecker, F.; Dintelmann, F.; Jakoby, R.

    1992-01-01

    Results of propagation measurements with the satellite OLYMPUS carried out at 12.5, 20, and 30 GHz at the Research Center of the Deutsche Bundespost Telekom are discussed. In particular, attenuation, scintillation, and depolarization measurements are analyzed with special emphasis on frequency scaling of the various effects.

  9. Effects of clouds on the Earth radiation budget; Seasonal and inter-annual patterns

    NASA Technical Reports Server (NTRS)

    Dhuria, Harbans L.

    1992-01-01

    Seasonal and regional variations of clouds and their effects on the climatological parameters were studied. The climatological parameters surface temperature, solar insulation, short-wave absorbed, long wave emitted, and net radiation were considered. The data of climatological parameters consisted of about 20 parameters of Earth radiation budget and clouds of 2070 target areas which covered the globe. It consisted of daily and monthly averages of each parameter for each target area for the period, Jun. 1979 - May 1980. Cloud forcing and black body temperature at the top of the atmosphere were calculated. Interactions of clouds, cloud forcing, black body temperature, and the climatological parameters were investigated and analyzed.

  10. Radiation transport and density effects in non-equilibrium plasmas

    NASA Astrophysics Data System (ADS)

    Fisher, Vladimir I.; Fisher, Dimitri V.; Maron, Yitzhak

    2007-05-01

    We describe a model for self-consistent computations of ionic level populations and the radiation field in transient non-equilibrium plasmas. In this model, the plasma density effects are described using the effective-statistical-weights (ESW) formalism based on the statistics of the microscopic environment of individual ions. In comparison to earlier work, the ESW formalism is expanded to a self-consistent treatment of the radiative transfer. For non-Maxwellian plasmas, the atomic-kinetics and radiative transfer computations may be performed for an arbitrary distribution of the free electrons. A plasma is presented by a finite number of cells, each with uniform thermodynamic parameters. The radiation field in each cell is computed by accounting for the radiation of entire plasma and of external sources. To demonstrate the predictions of the ESW approach and their difference from those of the traditional approach we apply the model to high-density plasmas. Based on hydrodynamic simulations of a laser-matter interaction, we use the model to analyze spectral line shapes, where the effects caused by the spatial dependence of the plasma flow velocity are demonstrated. In single-cell simulations, for acceleration of the computations, the model utilizes recently derived formula for the cell volume-average and direction-average specific intensity of radiation.

  11. Application of neural networks for determining optical parameters of strongly scattering media from the intensity profile of backscattered radiation

    SciTech Connect

    Kotova, S P; Maiorov, I V; Maiorova, A M

    2007-01-31

    We analyse the possibilities of simultaneous measuring three optical parameters of scattering media, namely, the scattering and absorption coefficients and the scattering anisotropy parameter by the intensity profile of backscattered radiation by using the neural network inversion method and the method of adaptive-network-based fuzzy inference system. The measurement errors of the absorption and scattering coefficients and the scattering anisotropy parameter are 20%, 5%, and 10%, respectively. (special issue devoted to multiple radiation scattering in random media)

  12. Correlated Uncertainties in Radiation Shielding Effectiveness

    NASA Technical Reports Server (NTRS)

    Werneth, Charles M.; Maung, Khin Maung; Blattnig, Steve R.; Clowdsley, Martha S.; Townsend, Lawrence W.

    2013-01-01

    The space radiation environment is composed of energetic particles which can deliver harmful doses of radiation that may lead to acute radiation sickness, cancer, and even death for insufficiently shielded crew members. Spacecraft shielding must provide structural integrity and minimize the risk associated with radiation exposure. The risk of radiation exposure induced death (REID) is a measure of the risk of dying from cancer induced by radiation exposure. Uncertainties in the risk projection model, quality factor, and spectral fluence are folded into the calculation of the REID by sampling from probability distribution functions. Consequently, determining optimal shielding materials that reduce the REID in a statistically significant manner has been found to be difficult. In this work, the difference of the REID distributions for different materials is used to study the effect of composition on shielding effectiveness. It is shown that the use of correlated uncertainties allows for the determination of statistically significant differences between materials despite the large uncertainties in the quality factor. This is in contrast to previous methods where uncertainties have been generally treated as uncorrelated. It is concluded that the use of correlated quality factor uncertainties greatly reduces the uncertainty in the assessment of shielding effectiveness for the mitigation of radiation exposure.

  13. Radiation Effects in Nuclear Waste Materials

    SciTech Connect

    Weber, William J.; Corrales, L. Rene; Ness, Nancy J.; Williford, Ralph E.; Heinisch, Howard L.; Thevuthasan, Suntharampillai; Icenhower, Jonathan P.; McGrail, B. Peter; Devanathan, Ramaswami; Van Ginhoven, Renee M.; Song, Jakyoung; Park, Byeongwon; Jiang, Weilin; Begg, Bruce D.; Birtcher, R. B.; Chen, X.; Conradson, Steven D.

    2000-10-02

    Radiation effects from the decay of radionuclides may impact the long-term performance and stability of nuclear waste forms and stabilized nuclear materials. In an effort to address these concerns, the objective of this project was the development of fundamental understanding of radiation effects in glasses and ceramics, particularly on solid-state radiation effects and their influence on aqueous dissolution kinetics. This study has employed experimental, theoretical and computer simulation methods to obtain new results and insights into radiation damage processes and to initiate the development of predictive models. Consequently, the research that has been performed under this project has significant implications for the High-Level Waste and Nuclear Materials focus areas within the current DOE/EM mission. In the High-Level Waste (HLW) focus area, the results of this research could lead to improvements in the understanding of radiation-induced degradation mechanisms and their effects on dissolution kinetics, as well as development of predictive models for waste form performance. In the Nuclear Materials focus area, the results of this research could lead to improvements in the understanding of radiation effects on the chemical and structural properties of materials for the stabilization and long-term storage of plutonium, highly-enriched uranium, and other actinides. Ultimately, this research could result in improved glass and ceramic materials for the stabilization and immobilization of high-level tank waste, plutonium residues and scraps, surplus weapons plutonium, highly-enriched uranium, other actinides, and other radioactive materials.

  14. Radiation thermometer size-of-source effect testing using aperture

    SciTech Connect

    Liebmann, F.; Kolat, T.

    2013-09-11

    Size-of-source effect is an important attribute of any radiation thermometer. The effects of this attribute may be quantified in a number of different ways to include field-of-view, distance ratio, or size-of-source effect. These parameters provide needed information for the user of a radiation thermometer, as they aid in determining whether the measured object is large enough for adequate radiation thermometry measurement. Just as important, these parameters provide needed information for calibration. This information helps to determine calibration geometry, and it is needed for calibration uncertainty determination. For determination of size-of-source effect, there are a limited number of test methods furnished by the standards available today. The test methods available may be cumbersome to perform due to the cost of the required equipment and the time needed to set-up and perform the test. Other methods have been proposed. This paper discusses one such method. This method uses a circular aperture such as that used in radiation thermometer calibration. It describes the method both theoretically and mechanically. It then discusses testing done to verify this method comparing the results to those obtained while performing steps in current standards. Finally, based on this testing, the basis for a new standard test method is presented.

  15. Effect of low-dose ionizing radiation on luminous marine bacteria: radiation hormesis and toxicity.

    PubMed

    Kudryasheva, N S; Rozhko, T V

    2015-04-01

    The paper summarizes studies of effects of alpha- and beta-emitting radionuclides (americium-241, uranium-235+238, and tritium) on marine microorganisms under conditions of chronic low-dose irradiation in aqueous media. Luminous marine bacteria were chosen as an example of these microorganisms; bioluminescent intensity was used as a tested physiological parameter. Non-linear dose-effect dependence was demonstrated. Three successive stages in the bioluminescent response to americium-241 and tritium were found: 1--absence of effects (stress recognition), 2--activation (adaptive response), and 3--inhibition (suppression of physiological function, i.e. radiation toxicity). The effects were attributed to radiation hormesis phenomenon. Biological role of reactive oxygen species, secondary products of the radioactive decay, is discussed. The study suggests an approach to evaluation of non-toxic and toxic stages under conditions of chronic radioactive exposure. PMID:25644753

  16. Effects of solar radiation on hair and photoprotection.

    PubMed

    Dario, Michelli F; Baby, André R; Velasco, Maria Valéria R

    2015-12-01

    In this paper the negative effects of solar radiation (ultraviolet, visible and infrared wavelengths) on hair properties like color, mechanical properties, luster, protein content, surface roughness, among others, will be discussed. Despite knowing that radiation damages hair, there are no consensus about the particular effect of each segment of solar radiation on the hair shaft. The hair photoprotection products are primarily targeted to dyed hair, specially auburn pigments, and gray shades. They are usually based on silicones, antioxidants and quaternary chemical UV filters that have more affinity for negatively charged hair surface and present higher efficacy. Unfortunately, there are no regulated parameters, like for skin photoprotection, for efficacy evaluation of hair care products, which makes impossible to compare the results published in the literature. Thus, it is important that researchers make an effort to apply experimental conditions similar to a real level of sun exposure, like dose, irradiance, time, temperature and relative humidity. PMID:26454659

  17. Radiation effect on rocket engine performance

    NASA Technical Reports Server (NTRS)

    Chiu, Huei-Huang

    1988-01-01

    The effects of radiation on the performance of modern rocket propulsion systems operating at high pressure and temperature were recognized as a key issue in the design and operation of various liquid rocket engines of the current and future generations. Critical problem areas of radiation coupled with combustion of bipropellants are assessed and accounted for in the formulation of a universal scaling law incorporated with a radiation-enhanced vaporization combustion model. Numerical algorithms are developed and the pertaining data of the Variable Thrust Engine (VTE) and Space Shuttle Main Engine (SSME) are used to conduct parametric sensitivity studies to predict the principal intercoupling effects of radiation. The analysis reveals that low enthalpy engines, such as the VTE, are vulnerable to a substantial performance set back by the radiative loss, whereas the performance of high enthalpy engines such as the SSME, are hardly affected over a broad range of engine operation. Additionally, combustion enhancement by the radiative heating of the propellant has a significant impact in those propellants with high absorptivity. Finally, the areas of research related with radiation phenomena in bipropellant engines are identified.

  18. On the measurement of in situ antenna radiation parameters from scattering measurements using a general scattering parametric model

    NASA Astrophysics Data System (ADS)

    Mendez, Enrique Alberto

    The new concept of antenna radiation center (ARC) is introduced and an empirical method to measure it from complex scattering data is presented. This concept is different from the well-known antenna phase center utilized in reflector antenna applications. A novel and efficient procedure based on a General Parametric Scattering Model (GSPM) is utilized to extract in-situ antenna radiation properties from complex antenna scattering data. This model based measurement approach has the advantage that it only requires two swept frequency scattering measurements in order to obtain antenna RCS, antenna gain and antenna radiation center in its integrated operational environment. The GSPM structure required to accurately extract arbitrary target scattering data is developed based on basic electromagnetic principles. The mathematical model structure consists of an early time response based on a point scattering model and on a late time response based on the Singularity Expansion Method (SEM). Both of these methods are implemented to take into account the target dispersion in a general fashion. Robust signal processing algorithms are utilized to extract the model parameters by exploiting the model symmetry properties in the time and frequency domains. In particular, super-resolution algorithms such as ESPRIT and MUSIC are utilized to extract scattering center location and resonance frequency information, while Least Squares techniques are used to estimate the different model amplitude coefficients as a function of time or frequency in an optimal (i.e. mean square sense) fashion. Theoretical derivations are provided to demonstrate that the GSPM can be utilized to extract antenna gain and radiation center information from scattering data. Synthetic and measured antenna scattering data are utilized to demonstrate the GSPM superior gain and radiation center results over traditional Fourier techniques. Gain transfer measurements results are also compared to the GSPM derived gain

  19. Occupational health effects of nonionizing radiation

    SciTech Connect

    Yost, M.G. )

    1992-07-01

    Nonionizing radiation includes electromagnetic energy distributed as near-ultraviolet and visible light, infrared radiation, microwaves, radio frequencies, and very low frequency and extremely low frequency alternating electric and magnetic fields, and almost every member of modern society is exposed to it in some form. Usually the intensity of exposure is low in the general population but can be greatly increased in the workplace. The forms of nonionizing radiation are described and their physical characteristics, occupational sources, biologic effects, and exposure criteria are delineated.90 references.

  20. Evidence of Dopant Type-Inversion and Other Radiation Damage Effects of the CDF Silicon Detectors

    SciTech Connect

    Martinez-Ballarin, Roberto

    2010-06-01

    The aim of this document is to study the effect of radiation damage on the silicon sensors. The reflection of the effect of radiation can be observed in two fundamental parameters of the detector: the bias current and the bias voltage. The leakage current directly affects the noise, while the bias voltage is required to collect the maximum signal deposited by the charged particle.

  1. Computed tomography imaging parameters for inhomogeneity correction in radiation treatment planning

    PubMed Central

    Das, Indra J.; Cheng, Chee-Wai; Cao, Minsong; Johnstone, Peter A. S.

    2016-01-01

    Modern treatment planning systems provide accurate dosimetry in heterogeneous media (such as a patient' body) with the help of tissue characterization based on computed tomography (CT) number. However, CT number depends on the type of scanner, tube voltage, field of view (FOV), reconstruction algorithm including artifact reduction and processing filters. The impact of these parameters on CT to electron density (ED) conversion had been subject of investigation for treatment planning in various clinical situations. This is usually performed with a tissue characterization phantom with various density plugs acquired with different tube voltages (kilovoltage peak), FOV reconstruction and different scanners to generate CT number to ED tables. This article provides an overview of inhomogeneity correction in the context of CT scanning and a new evaluation tool, difference volume dose-volume histogram (DVH), dV-DVH. It has been concluded that scanner and CT parameters are important for tissue characterizations, but changes in ED are minimal and only pronounced for higher density materials. For lungs, changes in CT number are minimal among scanners and CT parameters. Dosimetric differences for lung and prostate cases are usually insignificant (<2%) in three-dimensional conformal radiation therapy and < 5% for intensity-modulated radiation therapy (IMRT) with CT parameters. It could be concluded that CT number variability is dependent on acquisition parameters, but its dosimetric impact is pronounced only in high-density media and possibly in IMRT. In view of such small dosimetric changes in low-density medium, the acquisition of additional CT data for financially difficult clinics and countries may not be warranted. PMID:27051164

  2. Computed tomography imaging parameters for inhomogeneity correction in radiation treatment planning.

    PubMed

    Das, Indra J; Cheng, Chee-Wai; Cao, Minsong; Johnstone, Peter A S

    2016-01-01

    Modern treatment planning systems provide accurate dosimetry in heterogeneous media (such as a patient' body) with the help of tissue characterization based on computed tomography (CT) number. However, CT number depends on the type of scanner, tube voltage, field of view (FOV), reconstruction algorithm including artifact reduction and processing filters. The impact of these parameters on CT to electron density (ED) conversion had been subject of investigation for treatment planning in various clinical situations. This is usually performed with a tissue characterization phantom with various density plugs acquired with different tube voltages (kilovoltage peak), FOV reconstruction and different scanners to generate CT number to ED tables. This article provides an overview of inhomogeneity correction in the context of CT scanning and a new evaluation tool, difference volume dose-volume histogram (DVH), dV-DVH. It has been concluded that scanner and CT parameters are important for tissue characterizations, but changes in ED are minimal and only pronounced for higher density materials. For lungs, changes in CT number are minimal among scanners and CT parameters. Dosimetric differences for lung and prostate cases are usually insignificant (<2%) in three-dimensional conformal radiation therapy and < 5% for intensity-modulated radiation therapy (IMRT) with CT parameters. It could be concluded that CT number variability is dependent on acquisition parameters, but its dosimetric impact is pronounced only in high-density media and possibly in IMRT. In view of such small dosimetric changes in low-density medium, the acquisition of additional CT data for financially difficult clinics and countries may not be warranted. PMID:27051164

  3. The effects of radiation on angiogenesis.

    PubMed

    Grabham, Peter; Sharma, Preety

    2013-01-01

    The average human body contains tens of thousands of miles of vessels that permeate every tissue down to the microscopic level. This makes the human vasculature a prime target for an agent like radiation that originates from a source and passes through the body. Exposure to radiation released during nuclear accidents and explosions, or during cancer radiotherapy, is well known to cause vascular pathologies because of the ionizing effects of electromagnetic radiations (photons) such as gamma rays. There is however, another type of less well-known radiation - charged ion particles, and these atoms stripped of electrons, have different physical properties to the photons of electromagnetic radiation. They are either found in space or created on earth by particle collider facilities, and are of significant recent interest due to their enhanced effectiveness and increasing use in cancer radiotherapy, as well as a health risk to the growing number of people spending time in the space environment. Although there is to date, relatively few studies on the effects of charged particles on the vascular system, a very different picture of the biological effects of these particles compared to photons is beginning to emerge. These under researched biological effects of ion particles have a large impact on the health consequences of exposure. In this short review, we will discuss the effects of charged particles on an important biological process of the vascular system, angiogenesis, which creates and maintains the vasculature and is highly important in tumor vasculogenesis. PMID:24160185

  4. The effects of radiation on angiogenesis

    PubMed Central

    2013-01-01

    The average human body contains tens of thousands of miles of vessels that permeate every tissue down to the microscopic level. This makes the human vasculature a prime target for an agent like radiation that originates from a source and passes through the body. Exposure to radiation released during nuclear accidents and explosions, or during cancer radiotherapy, is well known to cause vascular pathologies because of the ionizing effects of electromagnetic radiations (photons) such as gamma rays. There is however, another type of less well-known radiation – charged ion particles, and these atoms stripped of electrons, have different physical properties to the photons of electromagnetic radiation. They are either found in space or created on earth by particle collider facilities, and are of significant recent interest due to their enhanced effectiveness and increasing use in cancer radiotherapy, as well as a health risk to the growing number of people spending time in the space environment. Although there is to date, relatively few studies on the effects of charged particles on the vascular system, a very different picture of the biological effects of these particles compared to photons is beginning to emerge. These under researched biological effects of ion particles have a large impact on the health consequences of exposure. In this short review, we will discuss the effects of charged particles on an important biological process of the vascular system, angiogenesis, which creates and maintains the vasculature and is highly important in tumor vasculogenesis. PMID:24160185

  5. Effect of processing parameters on autoclaved PMR polyimide composites

    NASA Technical Reports Server (NTRS)

    Vannucci, R. D.

    1977-01-01

    A study was conducted to determine the effect of processing parameters on the processability and properties of autoclaved fiber reinforced PMR polyimide composites. Composites were fabricated from commercially available graphite fabric and glass fabric PMR polyimide prepreg materials. Process parameters investigated included degree of resin advancement, heating rate, and cure pressure. Composites were inspected for porosity by ultrasonic C scan and photomicrographic examination. Processing characteristics for each set of process parameters and the effect of process parameters on composite mechanical properties at room temperature and 600 F are described.

  6. The application of distance transformation on parameter optimization of inverse planning in intensity-modulated radiation therapy.

    PubMed

    Yan, Hui; Yin, Fang-Fang

    2008-01-01

    In inverse planning for intensity-modulated radiation therapy (IMRT), the dose specification and related weighting factor of an objective function for involved organs is usually predefined by a single value and then iteratively optimized, subject to a set of dose-volume constraints. Because the actual dose distribution is essentially non-uniform and considerably affected by the geometric shape and distribution of the anatomic structures involved, the spatial information regarding those structures should be incorporated such that the predefined parameter distribution is made to approach the clinically expected distribution. Ideally, these parameter distributions should be predefined on a voxel basis in a manual method. However, such an approach is too time-consuming to be feasible in routine use. In the present study, we developed a computer-aided method to achieve the goal described above, producing a non-uniform parameter distribution based on spatial information about the anatomic structures involved. The method consists of two steps: Use distance transformation technique to calculate the distance distribution of the structures. Based on the distance distribution, produce the parameter distribution via a function guided by prior knowledge. We use two simulated cases to examine the effectiveness of the method. The results indicate that application of a non-uniform parameter distribution produced by distance transformation clearly improves dose-sparing of critical organs without compromising dose coverage of the planning target. PMID:18714279

  7. Radiation Effects on Spacecraft Structural Materials

    SciTech Connect

    Wang, Jy-An J.; Ellis, Ronald J.; Hunter, Hamilton T.; Singleterry, Robert C. Jr.

    2002-07-01

    Research is being conducted to develop an integrated technology for the prediction of aging behavior for space structural materials during service. This research will utilize state-of-the-art radiation experimental apparatus and analysis, updated codes and databases, and integrated mechanical and radiation testing techniques to investigate the suitability of numerous current and potential spacecraft structural materials. Also included are the effects on structural materials in surface modules and planetary landing craft, with or without fission power supplies. Spacecraft structural materials would also be in hostile radiation environments on the surface of the moon and planets without appreciable atmospheres and moons around planets with large intense magnetic and radiation fields (such as the Jovian moons). The effects of extreme temperature cycles in such locations compounds the effects of radiation on structural materials. This paper describes the integrated methodology in detail and shows that it will provide a significant technological advance for designing advanced spacecraft. This methodology will also allow for the development of advanced spacecraft materials through the understanding of the underlying mechanisms of material degradation in the space radiation environment. Thus, this technology holds a promise for revolutionary advances in material damage prediction and protection of space structural components as, for example, in the development of guidelines for managing surveillance programs regarding the integrity of spacecraft components, and the safety of the aging spacecraft. (authors)

  8. Radiative heating and cooling in the middle and lower atmosphere of Venus and responses to atmospheric and spectroscopic parameter variations

    NASA Astrophysics Data System (ADS)

    Haus, R.; Kappel, D.; Arnold, G.

    2015-11-01

    A sophisticated radiative transfer model that considers absorption, emission, and multiple scattering by gaseous and particulate constituents over the broad spectral range 0.125-1000 μm is applied to calculate radiative fluxes and temperature change rates in the middle and lower atmosphere of Venus (0-100 km). Responses of these quantities to spectroscopic and atmospheric parameter variations are examined in great detail. Spectroscopic parameter studies include the definition of an optimum spectral grid for monochromatic calculations as well as comparisons for different input data with respect to spectral line databases, continuum absorption, line shape factors, and solar irradiance spectra. Atmospheric parameter studies are based on distinct variations of an initial model data set. Analyses of actual variations of the radiative energy budget using atmospheric features that have been recently retrieved from Venus Express data will be subject of a subsequent paper. The calculated cooling (heating) rates are very reliable at altitudes below 95 (85) km with maximum uncertainties of about 0.25 K/day. Heating uncertainties may reach 3-5 K/day at 100 km. Using equivalent Planck radiation as solar insolation source in place of measured spectra is not recommended. Cooling rates strongly respond to variations of atmospheric thermal structure, while heating rates are less sensitive. The influence of mesospheric minor gas variations is small, but may become more important near the cloud base and in case of episodic SO2 boosts. Responses to cloud mode 1 particle abundance changes are weak, but variations of other mode parameters (abundances, cloud top and base altitudes) may significantly alter radiative temperature change rates up to 50% in Venus' lower mesosphere and upper troposphere. A new model for the unknown UV absorber for two altitude domains is proposed. It is not directly linked to cloud particle modes and permits an investigation of radiative effects regardless of

  9. Plutonium, Mineralogy and Radiation Effects

    NASA Astrophysics Data System (ADS)

    Ewing, R. C.

    2006-05-01

    During the past fifty years, more than 1,800 metric tonnes of Pu and substantial quantities of other "minor" actinides, such as Np, Am and Cm, have been generated in nuclear reactors. Some of these transuranic elements can be a source of energy in fission reactions (e.g., 239Pu), a source of fissile material for nuclear weapons (e.g., 239Pu and 237Np), or are of environmental concern because of their long half- lives and radiotoxicity (e.g., 239Pu, t1/2 = 24,100 years, and 237Np, t1/2 = 2.1 million years). There are two basic strategies for the disposition of these elements: 1.) to "burn" or transmute the actinides using nuclear reactors or accelerators; 2.) to "sequester" the actinides in chemically durable, radiation-resistant materials that are suitable for geologic disposal. There has been substantial interest in the use of actinide-bearing minerals, such as zircon or isometric pyrochlore, A2B2O7 (A = rare earths; B = Ti, Zr, Sn, Hf; Fd3m; Z=8), for the immobilization of actinides, particularly plutonium. One of the principal concerns has been the accumulation of structural damage caused by alpha-decay events, particularly from the recoil nucleus. Systematic ion beam irradiation studies of rare-earth pyrochlores have led to the discovery that certain compositions (B = Zr, Hf) are stable to very high fluences of alpha-decay event damage. Some compositions, Gd2Ti2O7, are amorphized at relatively low doses (0.2 displacements per atom, dpa, at room temperature), while other compositions, Gd2Zr2O7, do not amorphize (even at doses of > 40 dpa at 25K), but instead disorder to a defect fluorite structure. By changing the composition of the A-site (e.g., substitution of different rare earth elements), the temperature above which the pyrochlore composition can no longer be amorphized, Tc, varies by >600 K (e.g., Lu2Ti2O7: Tc = 480 K; Gd2Ti2O7: Tc = 1120 K). The variation in response to irradiation as a function of composition can be used to model the long

  10. Neutron Fluences and Radiation Damage Parameters for the HFIR-MFE-RB-17J Experiment

    SciTech Connect

    Greenwood, Lawrence R.; Glasgow, David C.; Baldwin, Charles A.

    2010-08-23

    The HFIR-MFE-RB-17J experiment was conducted in the removable beryllium (RB) position of HFIR with a Eu2O2 shield. The irradiation was conducted from April 27, 2004, to May 18, 2005. The total exposure was for 353.6 FPD (full power days). Reactor dosimetry capsules were analyzed and the activation data were used to provide the best estimates of the neutron fluences and radiation damage parameters as a function of height relative to midplane of the reactor.

  11. Radiation effects in LDD MOS devices

    SciTech Connect

    Woodruff, R.L.; Adams, J.R.

    1987-12-01

    The purpose of this work is to investigate the response of lightly doped drain (LDD) n-channel transistors to ionizing radiation. Transistors were fabricated with conventional (non-LDD) and lightly doped drain (LDD) structures using both standard (non-hardened) and radiation hardened gate oxides. Characterization of the transistors began with a correlation of the total-dose effects due to 10 keV x-rays with Co-60 gamma rays. The authors find that for the gate oxides and transistor structures investigated in this work, 10 keV x-rays produce more fixed-charge guild-up in the gate oxide, and more interface charge than do Co-60 gamma rays. They determined that the radiation response of LDD transistors is similar to that of conventional (non-LDD) transistors. In addition, both standard and radiation-hardened transistors subjected to hot carrier stress before irradiation show a similar radiation response. After exposure to 1.0 x 10/sup 6/ rads(Si), non-hardened transistors show increased susceptibility to hot-carrier graduation, while the radiation-hardened transistors exhibit similar hot-carrier degradation to non-irradiated devices. The authors have demonstrated a fully-integrated radiation hardened process tht is solid to 1.0 x 10/sup 6/ rads(Si), and shows promise for achieving 1.0 x 10/sup 7/ rad(Si) total-dose capability.

  12. Retrieval of atmospheric parameters and radiative properties using Far-Infrared remote sensing measurements

    NASA Astrophysics Data System (ADS)

    Jamali, Maryam; Milz, Mathias; Martín-Torres, Javier; Palchetti, Luca

    2016-04-01

    The far-infrared (FIR) spectral region, covering wavelengths between 15 μm (667 cm‑1) and about 1 μm (10,000 cm‑1) plays a critical role in the climate system. A good knowledge of the radiation processes in this spectral region is of high interest for observations and understanding of heating and cooling rates, and global energy balance. Even though approximately 50% of terrestrial radiation occurs in the FIR and despite the critical FIR contribution to the Earth's energy balance, this spectral region has been only studied by a few number of instruments. Also the full FIR spectral region has not ever been directly observed from space. High spectral resolution observations in this region can help to enlighten its role for the global energy budget and atmospheric radiation processes. Among others, the reasons for this lack of measurements are: (i) the decreasing intensity of the radiation towards longer wavelengths; and, then (ii) the high sensitivity and cooling of the detectors requirements. These requirements are now overcome and future space missions will have the capability to measure the full FIR and then open fully one-half of the Earth's spectrum, and accordingly improve our ability to model and assess climate processes. The aim of the study is to assess the use of FIR remote sensing instruments for retrievals of atmospheric parameters and radiative properties such as heating and cooling rates. Case studies with simulated spectra, together with ground based measurements in the FIR at Dome C over the Antarctic Plateau at 3,230 m a.s.l. (above sea level) in clear-sky conditions, which been observed almost continuously since 2012, are used to assess the potential of remote sensing instruments in the far-infrared region. Appropriate selection of spectral channels to directly measure the far-infrared spectra as needed for future space missions and recommended.

  13. CONTROL OF LASER RADIATION PARAMETERS: Mode locking in solid-state lasers by self-focusing

    NASA Astrophysics Data System (ADS)

    Kalashnikov, V. L.; Kalosha, V. P.; Mikhailov, V. P.; Poloiko, I. G.

    1995-11-01

    The self-consistent ABCD method is used to analyse the fundamental eigenmode of a four-mirror cavity with an active element and an aperture. Practical titanium-activated sapphire lasers with Kerr-lens mode locking are considered. The ranges of the cavity parameters are found in which the diffraction losses on an aperture are small and decrease with increase in the cavity field intensity as a result of self-focusing. These parameters of a four-mirror cavity are used to demonstrate that the investigated mechanism of discrimination of the radiation fluctuations should make it possible to generate a stable train of ultrashort pulses under conditions of cw and pulsed flashlamp pumping.

  14. Effect of correlated observation error on parameters, predictions, and uncertainty

    USGS Publications Warehouse

    Tiedeman, Claire R.; Green, Christopher T.

    2013-01-01

    Correlations among observation errors are typically omitted when calculating observation weights for model calibration by inverse methods. We explore the effects of omitting these correlations on estimates of parameters, predictions, and uncertainties. First, we develop a new analytical expression for the difference in parameter variance estimated with and without error correlations for a simple one-parameter two-observation inverse model. Results indicate that omitting error correlations from both the weight matrix and the variance calculation can either increase or decrease the parameter variance, depending on the values of error correlation (ρ) and the ratio of dimensionless scaled sensitivities (rdss). For small ρ, the difference in variance is always small, but for large ρ, the difference varies widely depending on the sign and magnitude of rdss. Next, we consider a groundwater reactive transport model of denitrification with four parameters and correlated geochemical observation errors that are computed by an error-propagation approach that is new for hydrogeologic studies. We compare parameter estimates, predictions, and uncertainties obtained with and without the error correlations. Omitting the correlations modestly to substantially changes parameter estimates, and causes both increases and decreases of parameter variances, consistent with the analytical expression. Differences in predictions for the models calibrated with and without error correlations can be greater than parameter differences when both are considered relative to their respective confidence intervals. These results indicate that including observation error correlations in weighting for nonlinear regression can have important effects on parameter estimates, predictions, and their respective uncertainties.

  15. Effect of radiation processing on meat tenderisation

    NASA Astrophysics Data System (ADS)

    Kanatt, Sweetie R.; Chawla, S. P.; Sharma, Arun

    2015-06-01

    The effect of radiation processing (0, 2.5, 5 and 10 kGy) on the tenderness of three types of popularly consumed meat in India namely chicken, lamb and buffalo was investigated. In irradiated meat samples dose dependant reduction in water holding capacity, cooking yield and shear force was observed. Reduction in shear force upon radiation processing was more pronounced in buffalo meat. Protein and collagen solubility as well as TCA soluble protein content increased on irradiation. Radiation processing of meat samples resulted in some change in colour of meat. Results suggested that irradiation leads to dose dependant tenderization of meat. Radiation processing of meat at a dose of 2.5 kGy improved its texture and had acceptable odour.

  16. Effects of ionizing radiation on CCD's

    NASA Technical Reports Server (NTRS)

    Hartsell, G. A.; Robinson, D. A.; Collins, D. R.

    1975-01-01

    The effects of 1.2 MeV gamma radiation and 20 MeV electrons on the operational characteristics of CCDs are studied. The effects of ionizing radiation on the charge transfer efficiency, dark current, and input/output circuitry are described. The improved radiation hardness of buried channel CCDs is compared to surface channel results. Both ion implanted and epitaxial layer buried channel device results are included. The advantages of using a single thickness SiO2 gate dielectric are described. The threshold voltage shifts and surface state density changes of dry, steam, and HCl doped oxides are discussed. Recent results on the recovery times and total dose effects of high dose rate pulses of 20 MeV electrons are reported.

  17. Radiation effects on Brassica seeds and seedlings

    NASA Astrophysics Data System (ADS)

    Deoli, Naresh; Hasenstein, Karl H.

    2016-07-01

    Space radiation consists of high energy charged particles and affects biological systems, but because of its stochastic, non-directional nature is difficult to replicate on Earth. Radiation damages biological systems acutely at high doses or cumulatively at low doses through progressive changes in DNA organization. These damages lead to death or cause of mutations. While radiation biology typically focuses on mammalian or human systems, little is known as to how radiation affects plants. In addition, energetic ion beams are widely used to generate new mutants in plants considering their high-LET (Linear Energy Transfer) as compared to gamma rays and X-rays. Understanding the effect of ionizing radiation on plant provides a basis for studying effects of radiation on biological systems and will help mitigate (space) radiation damage in plants. We exposed dry and imbibed Brassica rapa seeds and seedling roots to proton beams of varying qualities and compared the theoretical penetration range of different energy levels with observable growth response. We used 1, 2 and 3 MeV protons in air at the varying fluences to investigate the effect of direct irradiation on the seeds (1012 - 1015 ions/cm2) and seedlings (1013 ions/cm2). The range of protons in the tissue was calculated using Monte-Carlo based SRIM (Stopping and Range of Ions in Matter) software. The simulation and biological results indicate that ions did not penetrate the tissue of dry or hydrated seeds at all used ion energies. Therefore the entire energy was transferred to the treated tissue. Irradiated seeds were germinated vertically under dim light and roots growth was observed for two days after imbibition. The LD50 of the germination was about 2×1014 ions/cm2 and about 5×1014 ions/cm2 for imbibed and dry seeds, respectively. Since seedlings are most sensitive to gravity, the change in gravitropic behavior is a convenient means to assess radiation damage on physiological responses other than direct tissue

  18. Maximum entropy inference of seabed attenuation parameters using ship radiated broadband noise.

    PubMed

    Knobles, D P

    2015-12-01

    The received acoustic field generated by a single passage of a research vessel on the New Jersey continental shelf is employed to infer probability distributions for the parameter values representing the frequency dependence of the seabed attenuation and the source levels of the ship. The statistical inference approach employed in the analysis is a maximum entropy methodology. The average value of the error function, needed to uniquely specify a conditional posterior probability distribution, is estimated with data samples from time periods in which the ship-receiver geometry is dominated by either the stern or bow aspect. The existence of ambiguities between the source levels and the environmental parameter values motivates an attempt to partially decouple these parameter values. The main result is the demonstration that parameter values for the attenuation (α and the frequency exponent), the sediment sound speed, and the source levels can be resolved through a model space reduction technique. The results of this multi-step statistical inference developed for ship radiated noise is then tested by processing towed source data over the same bandwidth and source track to estimate continuous wave source levels that were measured independently with a reference hydrophone on the tow body. PMID:26723313

  19. Effects of space environment on composites: An analytical study of critical experimental parameters

    NASA Technical Reports Server (NTRS)

    Gupta, A.; Carroll, W. F.; Moacanin, J.

    1979-01-01

    A generalized methodology currently employed at JPL, was used to develop an analytical model for effects of high-energy electrons and interactions between electron and ultraviolet effects. Chemical kinetic concepts were applied in defining quantifiable parameters; the need for determining short-lived transient species and their concentration was demonstrated. The results demonstrates a systematic and cost-effective means of addressing the issues and show qualitative and quantitative, applicable relationships between space radiation and simulation parameters. An equally important result is identification of critical initial experiments necessary to further clarify the relationships. Topics discussed include facility and test design; rastered vs. diffuse continuous e-beam; valid acceleration level; simultaneous vs. sequential exposure to different types of radiation; and interruption of test continuity.

  20. Total-dose radiation effects data for semiconductor devices, volume 1. [radiation resistance of components for the Galileo Project

    NASA Technical Reports Server (NTRS)

    Price, W. E.; Martin, K. E.; Nichols, D. K.; Gauthier, M. K.; Brown, S. F.

    1981-01-01

    Steady-state, total-dose radiation test data are provided in graphic format, for use by electronic designers and other personnel using semiconductor devices in a radiation environment. Data are presented by JPL for various NASA space programs on diodes, bipolar transistors, field effect transistors, silicon-controlled rectifiers, and optical devices. A vendor identification code list is included along with semiconductor device electrical parameter symbols and abbreviations.

  1. Radiation damage effects in zircon

    NASA Astrophysics Data System (ADS)

    Trachenko, Kostya; Dove, Martin; Salje, Ekhard

    2002-03-01

    Zircon, ZrSiO_4, is important for geology and geochronology, and has been proposed as a host material to immobilize highly radioactive materials from dismantled weapons and nuclear waste from power stations [1]. In these applications zircon is exposed to alpha-irradiation. Computer simulations have started to be employed to simulate radiation damage in zircon [2], but the origin and microscopic mechanisms of the most important structural changes in zircon - unit cell expansion and large macroscopic swelling at higher doses, strong shear deformation of the crystalline lattice, and polymerization of SiOn units [3], remain unknown. Here, we perform the molecular dynamics simulation of highly energetic recoils in zircon. Basing on the simulation results, we propose the simple picture of the density change in the damaged region that consists of the depleted and densified matter. We find that the experimentally observed structural changes originate from the interaction of the damaged region with the surrounding crystalline lattice: the shear of the lattice around the damaged region causes shear deformation and expansion of the unit cells. The polymers of connected SiOn polyhedra are most commonly present in the densified shell at the periphery of the damaged region. [1] R C Ewing et al, J. Mater. Res. 10, 243 (1995); W J Weber et al, B E Burakov et al, in Scientific Basis for Nuclear Waste Management XIX, 25-32 and 33-40 (Plenum, New York, 1996); R C Ewing, et al in Crystalline Ceramics: Waste Forms for the Disposal of Weapons Plutonium, NATO Workshop Proceedings 65 (Academic Publishers, Dordrecht, The Netherlands, 1996). [2] B Park et al, Phys. Rev. B, 64, 174108 (1-16) (2001); J P Crocombette and D Ghaleb, J. Nucl. Mater., 295, 167 (2001); K Trachenko et al, J. Appl. Phys., 87, 7702 (2000); K Trachenko et al, J. Phys.: Cond. Matt., 13, 1947 (2001). [3] T Murakami et al, Am. Min., 76, 1510 (1991); H D Holland and D Gottfried, Acta Cryst. 8, 291 (1955).; W J Weber, J. Am

  2. Significance of certain rustler aquifer parameters for predicting long-term radiation doses from WIPP

    SciTech Connect

    Wofsy, C

    1980-09-01

    This report considers some aspects of the radionuclide transport modeling presented in documents published by the US Department of Energy (DOE) regarding the Waste Isolation Pilot Plant (WIPP) nuclear waste repository proposed for development in Southeastern New Mexico. The radionuclide transport modeling is used to predict worst possible consequences of a WIPP repository breach event in which waste enters groundwater. The aim of this report is to determine whether plausible changes in the parameters used by DOE to describe the flow of groundwater near the WIPP site could result in: (a) significantly faster radionuclide movement in groundwater; and (b) significantly higher concentrations of radionuclides in Pecos River water and correspondingly higher radiation doses than predicted by DOE. The conclusion reached is that while plausible changes in hydrologic conditions and waste-rock interactions might result in a significant reduction in the time it takes for radionuclides to reach the Pecos River, the shorter travel times do not result in significant increases in the estimated concentrations of radionuclides in the Pecos River nor in the radiation doses associated with the use of such water. Other ways in which parameter changes might affect these concentrations and doses are mentioned in the Conclusions section of the report, but are not the subject of this analysis.

  3. DECOHERENCE EFFECTS OF MOTION-INDUCED RADIATION

    SciTech Connect

    P. NETO; D. DALVIT

    2000-12-01

    The radiation pressure coupling with vacuum fluctuations gives rise to energy damping and decoherence of an oscillating particle. Both effects result from the emission of pairs of photons, a quantum effect related to the fluctuations of the Casimir force. We discuss different alternative methods for the computation of the decoherence time scale. We take the example of a spherical perfectly-reflecting particle, and consider the zero and high temperature limits. We also present short general reviews on decoherence and dynamical Casimir effect.

  4. Effects of radiation reaction in relativistic laser acceleration

    SciTech Connect

    Hadad, Y.; Labun, L.; Rafelski, J.; Elkina, N.; Klier, C.; Ruhl, H.

    2010-11-01

    The goal of this paper is twofold: to explore the response of classical charges to electromagnetic force at the level of unity in natural units and to establish a criterion that determines physical parameters for which the related radiation-reaction effects are detectable. In pursuit of this goal, the Landau-Lifshitz equation is solved analytically for an arbitrary (transverse) electromagnetic pulse. A comparative study of the radiation emission of an electron in a linearly polarized pulse for the Landau-Lifshitz equation and for the Lorentz force equation reveals the radiation-reaction-dominated regime, in which radiation-reaction effects overcome the influence of the external fields. The case of a relativistic electron that is slowed down by a counterpropagating electromagnetic wave is studied in detail. We further show that when the electron experiences acceleration of order unity, the dynamics of the Lorentz force equation, the Landau-Lifshitz equation and the Lorentz-Abraham-Dirac equation all result in different radiation emission that could be distinguished in experiment. Finally, our analytic and numerical results are compared with those appearing in the literature.

  5. Radiation Effects on Current Field Programmable Technologies

    NASA Technical Reports Server (NTRS)

    Katz, R.; LaBel, K.; Wang, J. J.; Cronquist, B.; Koga, R.; Penzin, S.; Swift, G.

    1997-01-01

    Manufacturers of field programmable gate arrays (FPGAS) take different technological and architectural approaches that directly affect radiation performance. Similar y technological and architectural features are used in related technologies such as programmable substrates and quick-turn application specific integrated circuits (ASICs). After analyzing current technologies and architectures and their radiation-effects implications, this paper includes extensive test data quantifying various devices total dose and single event susceptibilities, including performance degradation effects and temporary or permanent re-configuration faults. Test results will concentrate on recent technologies being used in space flight electronic systems and those being developed for use in the near term. This paper will provide the first extensive study of various configuration memories used in programmable devices. Radiation performance limits and their impacts will be discussed for each design. In addition, the interplay between device scaling, process, bias voltage, design, and architecture will be explored. Lastly, areas of ongoing research will be discussed.

  6. Monte Carlo study of the measurement of the Michel parameters in the radiative decay of the τ at Belle

    NASA Astrophysics Data System (ADS)

    Shimizu, N.; Aihara, H.; Epifanov, D.

    2016-07-01

    Michel parameters are kinematic values defined as bilinear combinations of the coupling terms in the general matrix element of the Fermi interaction where all possible Lorentz-invariant scalar, vector and tensor terms are included. The leptonic τ decays provide an excellent laboratory in which to measure the Michel parameters. Any deviation of these parameters from the Standard Model expectation would indicate New Physics. Two Michel parameters, η bar and ξκ, can only be measured in the radiative leptonic decay. These parameters have previously been measured in the radiative decay of the muon but as yet have not been measured in τ decays. We report the results of a feasibility study of the measurement of η bar and ξκ in radiative leptonic τ decays at Belle and Belle II.

  7. Predictive biochemical assays for late radiation effects

    SciTech Connect

    Rubin, P.; Finkelstein, J.N.; Siemann, D.W.; Shapiro, D.L.; Van Houtte, P.; Penney, D.P.

    1986-04-01

    Surfactant precursors or other products of Type II pneumocytes have the potential to be the first biochemical marker for late radiation effects. This is particularly clinically important in the combined modality era because of the frequent occurrence of pneumonitis and pulmonary fibrosis secondary to radiation or chemotherapy. Accordingly, correlative studies have been pursued with the Type II pneumocyte as a beginning point to understand the complex pathophysiology of radiation pneumonitis and fibrosis. From our ultrastructural and biochemical studies, it is evident that Type II pneumocytes are an early target of radiation and the release of surfactant into the alveolus shortly after exposure persists for days and weeks. Through the use of lavaging techniques, alveolar surfactant has been elevated after pulmonary irradiation. In three murine strains and in the rabbit, there is a strong correlation with surfactant release at 7 and/or 28 days in vivo with later lethality in months. In vitro studies using cultures of type II pneumocytes also demonstrate dose response and tolerance factors that are comparable to the in vivo small and large animal diagnostic models. New markers are being developed to serve as a predictive index for later lethal pneumonopathies. With the development of these techniques, the search for early biochemical markers in man has been undertaken. Through the use of biochemical, histological, and ultrastructural techniques, a causal relationship between radiation effects on type II pneumocytes, pulmonary cells, endothelial cells of blood vessels, and their roles in the production of pneumonitis and fibrosis will evolve.

  8. GENETIC AND CELLULAR EFFECTS OF MICROWAVE RADIATIONS

    EPA Science Inventory

    This research program was initiated with the overall objective of determining genetic and cellular effects from exposure of unicellular organisms to selected frequencies of CW and pulsed microwave radiation which is prevalent in the biosphere. Several tester strains of the bacter...

  9. Radiation damage effects in polarized deuterated ammonia

    SciTech Connect

    P.M. McKee

    2003-07-01

    Solid polarized targets utilizing deuterated ammonia, {sup 15}ND{sub 3}, offer an attractive combination of high polarization, high dilution factor and high resistance to polarization losses from radiation damage. Jefferson Laboratory Experiment E93-026 used {sup 15}ND{sub 3} as a target material in a five-month form factor measurement, allowing a detailed study of it's performance. The dependence of the deuteron polarization on received dose by the ammonia and the effectiveness of annealing the material to recover performance lost to radiation damage will be discussed.

  10. Laser radiation effects on Mycoplasma agalactiae

    NASA Astrophysics Data System (ADS)

    Dinu, Cerasela Z.; Grigoriu, Constantin; Dinescu, Maria; Pascale, Florentina; Popovici, Adrian; Gheorghescu, Lavinia; Cismileanu, Ana; Avram, Eugenia

    2002-08-01

    The biological effects of the laser radiation emitted by the Nd:YAG laser (second harmonic, wavelength 532 nm /fluence 32 mJ/cm2/pulse duration 6 ns) on the Mycoplasma agalactiae bacterium were studied. The radiation was found to intensify the multiplication of the bacteria irradiated in TRIS buffer (0.125 M), without however affecting the proteinic composition of the cell membrane. When the bacteria were irradiated in their growth medium (PPLO broth) being later cultivated on a solid medium (PPLO agar), the exclusive presence of the atypical colonies (granular and T-like ones) was noticed.

  11. Effects of fast neutron radiation on polypropylene

    SciTech Connect

    Cygan, S.; Laghari, J.R. . Dept. of Electrical and Computer Engineering)

    1989-08-01

    Capacitor-grade polypropylene films were irradiated in a 2-MW thermal nuclear reactor and exposed to fast neutron radiation at a flux rate of 2.6 x 10/sup 12/ neutron/cm/sup 2/s and gamma radiation at a level of 10/sup 7/ rad/h. The postirradiation effects on changes in the electrical and chemical properties of the films were studied for irradiation times up to 10 h. The electrical properties were dc and ac breakdown voltages, life under pulsed voltage stress, dielectric permittivity, dielectric losses, and volume resistivity. Chemical analysis was performed using the infrared spectroscopy technique. The results are discussed in this paper.

  12. Inverse Faraday effect driven by radiation friction

    NASA Astrophysics Data System (ADS)

    Liseykina, T. V.; Popruzhenko, S. V.; Macchi, A.

    2016-07-01

    A collective, macroscopic signature to detect radiation friction in laser–plasma experiments is proposed. In the interaction of superintense circularly polarized laser pulses with high density targets, the effective dissipation due to radiative losses allows the absorption of electromagnetic angular momentum, which in turn leads to the generation of a quasistatic axial magnetic field. This peculiar ‘inverse Faraday effect’ is investigated by analytical modeling and three-dimensional simulations, showing that multi-gigagauss magnetic fields may be generated at laser intensities \\gt {10}23 {{{W}}{{cm}}}-2.

  13. The absorption of solar radiation by the Arctic atmosphere during the haze season and its effects on the radiation balance

    NASA Technical Reports Server (NTRS)

    Valero, F. P. J.; Ackerman, T. P.; Gore, W. J. Y.

    1984-01-01

    Measurements of broadband spectral absorption of solar radiation by the Arctic atmosphere during haze events are reported. A preliminary analysis of the data indicates that large changes occur in the radiative transfer processes in the Arctic during haze events. For example, the planetary albedo is estimated to increase by 2.5 percent over the ocean and to decrease by 9 percent over the ice cap. Changes of such magnitude in the radiative parameters have the potential for significant climatic effects. The need for further experimental and modeling efforts is emphasized.

  14. LDEF solar cell radiation effects analysis

    NASA Technical Reports Server (NTRS)

    Rives, Carol J.; Azarewicz, Joseph L.; Massengill, Lloyd

    1993-01-01

    Because of the extended time that the Long Duration Exposure Facility (LDEF) mission stayed in space, the solar cells on the satellite experienced greater environments than originally planned. The cells showed an overall degradation in performance that is due to the combined effects of the various space environments. The purpose of this analysis is to calculate the effect of the accumulated radiation on the solar cells, thereby helping Marshall Space Flight Center (MSFC) to unravel the relative power degradation from the different environments.

  15. Inlet contour and flow effects on radiation

    NASA Technical Reports Server (NTRS)

    Ville, J. M.; Silcox, R. J.

    1980-01-01

    An experimental investigation of sound radiation from inlets with different contours with and without flow is being conducted to study the possibility of reducing noise radiated by aircraft engines. For each inlet configuration, complex directivity patterns and complex pressure reflection coefficients are measured as a function of a single space-time structure of the wave (up to a frequency of 4000Hz and an azimuthal wave number 6) and of flow velocity (up to Mach number 0.4) in a cylindrical duct located downstream the inlet. Experimental results of radiation from an unflanged duct are compared with theory. Effect of inlet contour and flow are deduced by comparing respectively unflanged duct and bellmouth measurements and, no flow and flow measurements with the bellmouth. Results are presented which indicate that the contour effect is significant near the cut-on frequency of a mode and emphasize the necessity for taking into account the inlet geometry in a radiation prediction. These results show also that internal flow has a weak effect on the amplitude of the directivity pattern

  16. Inlet contour and flow effects on radiation

    NASA Astrophysics Data System (ADS)

    Ville, J. M.; Silcox, R. J.

    1980-06-01

    An experimental investigation of sound radiation from inlets with different contours with and without flow is being conducted to study the possibility of reducing noise radiated by aircraft engines. For each inlet configuration, complex directivity patterns and complex pressure reflection coefficients are measured as a function of a single space-time structure of the wave (up to a frequency of 4000Hz and an azimuthal wave number 6) and of flow velocity (up to Mach number 0.4) in a cylindrical duct located downstream the inlet. Experimental results of radiation from an unflanged duct are compared with theory. Effect of inlet contour and flow are deduced by comparing respectively unflanged duct and bellmouth measurements and, no flow and flow measurements with the bellmouth. Results are presented which indicate that the contour effect is significant near the cut-on frequency of a mode and emphasize the necessity for taking into account the inlet geometry in a radiation prediction. These results show also that internal flow has a weak effect on the amplitude of the directivity pattern

  17. Terahertz Radiation Effects and Biological Applications

    NASA Astrophysics Data System (ADS)

    Ramundo Orlando, Alfonsina; Gallerano, Gian Piero

    2009-12-01

    We present a brief overview of the literature on biological applications and experimental data on the effects of THz radiation. The region of the electromagnetic spectrum from 0.1 to 10 THz is a frontier area for research in physics, chemistry, biology, materials science and medicine. This area has recently begun to be filled by a variety of sources of high quality radiation with a wide range of new technologies related to it. New sources have led to new science in many areas, as scientists begin to become aware of the opportunities for research progress in their fields using THz radiation. Therefore the opportunities for THz science in chemistry and biology are wide ranging. Some of them will extend the range of already established work, many others have not yet been realized but show great promise, and the rest fall somewhere in between.

  18. Radiation effects and crystallinity in polyethylene

    NASA Astrophysics Data System (ADS)

    Keller, A.; Ungar, G.

    A survey is presented of a series of works on the influence of crystallinity on the radiation induced effects, cross-linking in particular, in polyethylene and paraffins. The principal theme is that the usual conception of random introduction of cross-links into a random assembly of chains needs to be modified in the presence of crystallinity in general and chain folding in particular. A long series of varied investigations on polyethylene have indeed demonstrated through a series of conspicuous effects that not only the ordering intrinsic to crystals and the increased intrachain contacts due to chain folding, but the higher level morphology, the nature and mutual arrangement in particular, have a major influence on the effectivity of the radiation leading to networks. Extension of the works to paraffins identified unsuspected mobility of both the radiation precursor species and the paraffin molecule itself (cross-linked and uncross-linked) within the crystal lattice, leading to phase segregation of the cross-linked species into microscopically identifiable domains together with identifying a trend for the cross-links themselves to form non-randomly in groups. The latter phenomenon, observed also in the molten state, indicates that the departure from randomness in the cross-linking process is much more deep-rooted than originally anticipated, and calls for a general reassessment of our knowledge of cross-linking. Other topics included as part of the general enquiry are the destruction of crystallinity, the promotion of hexagonal phase through radiation, the effect of morphology on chain scission and the general, still unsolved issue of how to assess cross-links by a direct analytical method (involving NMR). The hope is expressed that the bringing together of these varied pieces of work will serve the unification of presently widely diverse areas of experience and might influence developments in the radiation studies of paraffinoid substances.

  19. Effect of viscoplastic material parameters on polymer indentation

    NASA Astrophysics Data System (ADS)

    Tvergaard, V.; Needleman, A.

    2012-09-01

    The effect of material parameters characterizing viscoplastic flow on the indentation response of polymers is investigated using three-dimensional finite element analyses and a one-dimensional expanding spherical cavity model. The polymer is characterized by a finite strain elastic-viscoplastic constitutive relation and two indenter shapes are considered; a conical indenter and a pyramidal indenter. The ability of the simpler expanding spherical cavity model to reproduce the trends obtained from the finite element solutions is assessed for both indenter shapes. Within the range of parameter variations considered, it is found that two material stress parameters characterizing the plastic flow resistance have the largest effect on the value of the indentation hardness although variations in other material parameters can lead to significant variations.

  20. An automatic and effective parameter optimization method for model tuning

    NASA Astrophysics Data System (ADS)

    Zhang, T.; Li, L.; Lin, Y.; Xue, W.; Xie, F.; Xu, H.; Huang, X.

    2015-11-01

    Physical parameterizations in general circulation models (GCMs), having various uncertain parameters, greatly impact model performance and model climate sensitivity. Traditional manual and empirical tuning of these parameters is time-consuming and ineffective. In this study, a "three-step" methodology is proposed to automatically and effectively obtain the optimum combination of some key parameters in cloud and convective parameterizations according to a comprehensive objective evaluation metrics. Different from the traditional optimization methods, two extra steps, one determining the model's sensitivity to the parameters and the other choosing the optimum initial value for those sensitive parameters, are introduced before the downhill simplex method. This new method reduces the number of parameters to be tuned and accelerates the convergence of the downhill simplex method. Atmospheric GCM simulation results show that the optimum combination of these parameters determined using this method is able to improve the model's overall performance by 9 %. The proposed methodology and software framework can be easily applied to other GCMs to speed up the model development process, especially regarding unavoidable comprehensive parameter tuning during the model development stage.

  1. Working group written presentation: Trapped radiation effects

    NASA Technical Reports Server (NTRS)

    Vampola, Alfred L.; Stuckey, Wayne K.; Coulter, D.; Friebele, E. J.; Hand, K. J.; Hardy, D. A.; Higby, P.; Kolasinski, W. A.; Santoro, R. T.; Tompkins, Stephen S.

    1989-01-01

    The results of the Trapped Radiation Effects Panel for the Space Environmental Effects on Materials Workshop are presented. The needs of the space community for new data regarding effects of the space environment on materials, including electronics are listed. A series of questions asked of each of the panels at the workshop are addressed. Areas of research which should be pursued to satisfy the requirements for better knowledge of the environment and better understanding of the effects of the energetic charged particle environment on new materials and advanced electronics technology are suggested.

  2. Neural network radiative transfer solvers for the generation of high resolution solar irradiance spectra parameterized by cloud and aerosol parameters

    NASA Astrophysics Data System (ADS)

    Taylor, M.; Kosmopoulos, P. G.; Kazadzis, S.; Keramitsoglou, I.; Kiranoudis, C. T.

    2016-01-01

    This paper reports on the development of a neural network (NN) model for instantaneous and accurate estimation of solar radiation spectra and budgets geared toward satellite cloud data using a ≈2.4 M record, high-spectral resolution look up table (LUT) generated with the radiative transfer model libRadtran. Two NN solvers, one for clear sky conditions dominated by aerosol and one for cloudy skies, were trained on a normally-distributed and multiparametric subset of the LUT that spans a very broad class of atmospheric and meteorological conditions as inputs with corresponding high resolution solar irradiance target spectra as outputs. The NN solvers were tested by feeding them with a large (10 K record) "off-grid" random subset of the LUT spanning the training data space, and then comparing simulated outputs with target values provided by the LUT. The NN solvers demonstrated a capability to interpolate accurately over the entire multiparametric space. Once trained, the NN solvers allow for high-speed estimation of solar radiation spectra with high spectral resolution (1 nm) and for a quantification of the effect of aerosol and cloud optical parameters on the solar radiation budget without the need for a massive database. The cloudy sky NN solver was applied to high spatial resolution (54 K pixel) cloud data extracted from the Spinning Enhanced Visible and Infrared Imager (SEVIRI) onboard the geostationary Meteosat Second Generation 3 (MSG3) satellite and demonstrated that coherent maps of spectrally-integrated global horizontal irradiance at this resolution can be produced on the order of 1 min.

  3. Hyper fast radiative transfer for the physical retrieval of surface parameters from SEVIRI observations

    NASA Astrophysics Data System (ADS)

    Liuzzi, G.; Masiello, G.; Serio, C.; Blasi, M. G.; Venafra, S.

    2015-09-01

    This paper describes the theoretical aspects of a fast scheme for the physical retrieval of surface temperature and emissivity from SEVIRI data, their implementation and some sample results obtained. The scheme is based on a Kalman Filter approach, which effectively exploits the temporal continuity in the observations of the geostationary Meteosat Second Generation (MSG) platform, on which SEVIRI (Spinning Enhanced Visible and InfraRed Imager) operates. Such scheme embodies in its core a physical retrieval algorithm, which employs an hyper fast radiative transfer code highly customized for this retrieval task. Radiative transfer and its customizations are described in detail. Fastness, accuracy and stability of the code are fully documented for a variety of surface features, showing a peculiar application to the massive Greek forest fires in August 2007.

  4. [On Individualization of Therapeutic Doses of Optical Radiation according to Changes in Parameters of Blood Oxygenation].

    PubMed

    Zalesskaya, G A

    2015-01-01

    The effect of in vivo laser irradiation by optical radiation on blood from different patients is studied. The objects of research were three series of blood samples from patients whose treatment course included extracorporeal UV blood irradiation, intravenous laser blood irradiation and supra-venous blood laser irradiation. Before and after irradiation the results on optic oximetry and gas content of venous blood were compared. The results of positive and negative influence of blood irradiation on characteristics of an oxygen exchange in separate patients and on the maintenance of some products of metabolism are represented. It is shown that at the same power dose, their changes depend on individual, initial values of hemoglobin oxygen saturation of venous blood and its photoinduced changes which objectively reflect individual sensitivity of patients to the action of optical radiation on blood and can be used for assessment of the efficiency of phototherapy. PMID:26349218

  5. Key Parameters for the Inconsistencies of the Incoming Solar Radiation Boundary Condition in Global Modeling

    NASA Astrophysics Data System (ADS)

    Tsushima, Yoko; Raschke, Ehrhard; Kinne, Stefan; Abe-Ouchi, Ayako; Bakan, Stefan; Emori, Seita; Giorgetta, Marco; Kopp, Greg; Saito, Fuyuki; Timm, Oliver; Wild, Martin

    2009-03-01

    By a comparison of the insolation, computed by 19 different climate models for the International Panel on Climate Change Fourth Assessment Report (IPCC-AR4) test period from 1980 to 1999, it is shown that those models used different values for the solar constant and for its solar cycle variations. Meridional profiles for the monthly incoming radiation displayed diversities of up to ±10 Wm-2, especially during the transient seasons. Sensitivity studies with minima and maxima for the assumed orbital parameters of the Earth show almost no change. However, the different temporal partitioning for onset and length of individual months based on different calendars (e.g. simplifications such as 30 days for each month) results in the difference in the insolation, which is strongly resemble in amount and in zonal pattern the observed diversity of the insolation in IPCC models. Contributing error sources are also different assumptions for cut-off angles at low sun-elevations and differences in increment-difference during spatial and temporal integrations. Possible impacts of these contributing errors in climate modeling are investigated within a coupled ocean-atmosphere model. It is found that monthly radiative fluxes, humidity, and temperature have a difference between the two vernal equinox experiments. Although it remained within the magnitude of the inter-model difference, the difference is systematic.

  6. SU-E-T-295: Simultaneous Beam Sampling and Aperture Shape Optimization for Station Parameter Optimized Radiation Therapy (SPORT)

    SciTech Connect

    Zarepisheh, M; Li, R; Xing, L; Ye, Y; Boyd, S

    2014-06-01

    Purpose: Station Parameter Optimized Radiation Therapy (SPORT) was recently proposed to fully utilize the technical capability of emerging digital LINACs, in which the station parameters of a delivery system, (such as aperture shape and weight, couch position/angle, gantry/collimator angle) are optimized altogether. SPORT promises to deliver unprecedented radiation dose distributions efficiently, yet there does not exist any optimization algorithm to implement it. The purpose of this work is to propose an optimization algorithm to simultaneously optimize the beam sampling and aperture shapes. Methods: We build a mathematical model whose variables are beam angles (including non-coplanar and/or even nonisocentric beams) and aperture shapes. To solve the resulting large scale optimization problem, we devise an exact, convergent and fast optimization algorithm by integrating three advanced optimization techniques named column generation, gradient method, and pattern search. Column generation is used to find a good set of aperture shapes as an initial solution by adding apertures sequentially. Then we apply the gradient method to iteratively improve the current solution by reshaping the aperture shapes and updating the beam angles toward the gradient. Algorithm continues by pattern search method to explore the part of the search space that cannot be reached by the gradient method. Results: The proposed technique is applied to a series of patient cases and significantly improves the plan quality. In a head-and-neck case, for example, the left parotid gland mean-dose, brainstem max-dose, spinal cord max-dose, and mandible mean-dose are reduced by 10%, 7%, 24% and 12% respectively, compared to the conventional VMAT plan while maintaining the same PTV coverage. Conclusion: Combined use of column generation, gradient search and pattern search algorithms provide an effective way to optimize simultaneously the large collection of station parameters and significantly improves

  7. Estimation of Microphysical and Radiative Parameters of Precipitating Cloud Systems Using mm-Wavelength Radars

    NASA Astrophysics Data System (ADS)

    Matrosov, Sergey Y.

    2009-03-01

    A remote sensing approach is described to retrieve cloud and rainfall parameters within the same precipitating system. This approach is based on mm-wavelength radar signal attenuation effects which are observed in a layer of liquid precipitation containing clouds and rainfall. The parameters of ice clouds in the upper part of startiform precipitating systems are then retrieved using the absolute measurements of radar reflectivity. In case of the ground-based radar location, these measurements are corrected for attenuation in the intervening layer of liquid hydrometers.

  8. Expected radiation effects in plutonium immobilization ceramic

    SciTech Connect

    Van Konynenburg, R.A., LLNL

    1997-09-01

    The current formulation of the candidate ceramic for plutonium immobilization consists primarily of pyrochlore, with smaller amounts of hafnium-zirconolite, rutile, and brannerite or perovskite. At a plutonium loading of 10.5 weight %, this ceramic would be made metamict (amorphous) by radiation damage resulting from alpha decay in a time much less than 10,000 years, the actual time depending on the repository temperature as a function of time. Based on previous experimental radiation damage work by others, it seems clear that this process would also result in a bulk volume increase (swelling) of about 6% for ceramic that was mechanically unconfined. For the candidate ceramic, which is made by cold pressing and sintering and has porosity amounting to somewhat more than this amount, it seems likely that this swelling would be accommodated by filling in the porosity, if the material were tightly confined mechanically by the waste package. Some ceramics have been observed to undergo microcracking as a result of radiation-induced anisotropic or differential swelling. It is unlikely that the candidate ceramic will microcrack extensively, for three reasons: (1) its phase composition is dominated by a single matrix mineral phase, pyrochlore, which has a cubic crystal structure and is thus not subject to anisotropic swelling; (2) the proportion of minor phases is small, minimizing potential cracking due to differential swelling; and (3) there is some flexibility in sintering process parameters that will allow limitation of the grain size, which can further limit stresses resulting from either cause.

  9. Drosophila Melanogaster Show a Threshold Effect in Response to Radiation

    PubMed Central

    Antosh, Michael; Fox, David; Hasselbacher, Thomas; Lanou, Robert; Neretti, Nicola; Cooper, Leon N.

    2014-01-01

    We investigate the biological effects of radiation using adult Drosophila melanogaster as a model organism, focusing on gene expression and lifespan analysis to determine the effect of different radiation doses. Our results support a threshold effect in response to radiation: no effect on lifespan and no permanent effect on gene expression is seen at incident radiation levels below 100 J/kg. We also find that it is more appropriate to compare radiation effects in flies using the absorbed energy rather than incident radiation levels. PMID:25552957

  10. An Effective Parameter Screening Strategy for High Dimensional Watershed Models

    NASA Astrophysics Data System (ADS)

    Khare, Y. P.; Martinez, C. J.; Munoz-Carpena, R.

    2014-12-01

    Watershed simulation models can assess the impacts of natural and anthropogenic disturbances on natural systems. These models have become important tools for tackling a range of water resources problems through their implementation in the formulation and evaluation of Best Management Practices, Total Maximum Daily Loads, and Basin Management Action Plans. For accurate applications of watershed models they need to be thoroughly evaluated through global uncertainty and sensitivity analyses (UA/SA). However, due to the high dimensionality of these models such evaluation becomes extremely time- and resource-consuming. Parameter screening, the qualitative separation of important parameters, has been suggested as an essential step before applying rigorous evaluation techniques such as the Sobol' and Fourier Amplitude Sensitivity Test (FAST) methods in the UA/SA framework. The method of elementary effects (EE) (Morris, 1991) is one of the most widely used screening methodologies. Some of the common parameter sampling strategies for EE, e.g. Optimized Trajectories [OT] (Campolongo et al., 2007) and Modified Optimized Trajectories [MOT] (Ruano et al., 2012), suffer from inconsistencies in the generated parameter distributions, infeasible sample generation time, etc. In this work, we have formulated a new parameter sampling strategy - Sampling for Uniformity (SU) - for parameter screening which is based on the principles of the uniformity of the generated parameter distributions and the spread of the parameter sample. A rigorous multi-criteria evaluation (time, distribution, spread and screening efficiency) of OT, MOT, and SU indicated that SU is superior to other sampling strategies. Comparison of the EE-based parameter importance rankings with those of Sobol' helped to quantify the qualitativeness of the EE parameter screening approach, reinforcing the fact that one should use EE only to reduce the resource burden required by FAST/Sobol' analyses but not to replace it.

  11. Comparative Evaluation of Inversion Approaches of the Radiative Transfer Model for Estimation of Crop Biophysical Parameters

    NASA Astrophysics Data System (ADS)

    Mridha, Nilimesh; Sahoo, Rabi N.; Sehgal, Vinay K.; Krishna, Gopal; Pargal, Sourabh; Pradhan, Sanatan; Gupta, Vinod K.; Kumar, Dasika Nagesh

    2015-04-01

    The inversion of canopy reflectance models is widely used for the retrieval of vegetation properties from remote sensing. This study evaluates the retrieval of soybean biophysical variables of leaf area index, leaf chlorophyll content, canopy chlorophyll content, and equivalent leaf water thickness from proximal reflectance data integrated broadbands corresponding to moderate resolution imaging spectroradiometer, thematic mapper, and linear imaging self scanning sensors through inversion of the canopy radiative transfer model, PROSAIL. Three different inversion approaches namely the look-up table, genetic algorithm, and artificial neural network were used and performances were evaluated. Application of the genetic algorithm for crop parameter retrieval is a new attempt among the variety of optimization problems in remote sensing which have been successfully demonstrated in the present study. Its performance was as good as that of the look-up table approach and the artificial neural network was a poor performer. The general order of estimation accuracy for parameters irrespective of inversion approaches was leaf area index > canopy chlorophyll content > leaf chlorophyll content > equivalent leaf water thickness. Performance of inversion was comparable for broadband reflectances of all three sensors in the optical region with insignificant differences in estimation accuracy among them.

  12. Hourly global and diffuse radiation of Lagos, Nigeria-correlation with some atmospheric parameters

    SciTech Connect

    Chendo, M.A.C.; Maduekwe, A.A.L. )

    1994-03-01

    The influence of four climatic parameters on the hourly diffuse fraction in Lagos, Nigeria, has been studied. Using data for two years, new correlations were established. The standard error of the Liu and Jordan-type equation was reduced by 12.83% when solar elevation, ambient temperature, and relative humidity were used together as predictor variables for the entire data set. Ambient temperature and relative humidity proved to be very important variables for predicting the diffuse fraction of the solar radiation passing through the humid atmosphere of the coastal and tropic city of Lagos. Seasonal analysis carried out with the data showed improvements on the standard errors for the new seasonal correlations. In the case of the dry season, the improvement was 18.37%, whole for the wet season, this was 12.37%. Comparison with existing correlations showed that the performance of the one parameter model (namely K[sub t]), of Orgill and Hollands and Reindl, Beckman, and Duffie were very different from the Liu and Jordan-type model obtained for Lagos.

  13. Radiation effects in IRAS extrinsic infrared detectors

    NASA Technical Reports Server (NTRS)

    Varnell, L.; Langford, D. E.

    1982-01-01

    During the calibration and testing of the Infrared Astronomy Satellite (IRAS) focal plane, it was observed that the extrinsic photoconductor detectors were affected by gamma radiation at dose levels of the order of one rad. Since the flight environment will subject the focal plane to dose levels of this order from protons in single pass through the South Atlantic Anomaly, an extensive program of radiation tests was carried out to measure the radiation effects and to devise a method to counteract these effects. The effects observed after irradiation are increased responsivity, noise, and rate of spiking of the detectors after gamma-ray doses of less than 0.1 rad. The detectors can be returned almost to pre-irradiation performance by increasing the detector bias to breakdown and allowing a large current to flow for several minutes. No adverse effects on the detectors have been observed from this bias boost, and this technique will be used for IRAS with frequent calibration to ensure the accuracy of observations made with the instrument.

  14. Structuring of material parameters in lithium niobate crystals with low-mass, high-energy ion radiation

    NASA Astrophysics Data System (ADS)

    Peithmann, K.; Eversheim, P.-D.; Goetze, J.; Haaks, M.; Hattermann, H.; Haubrich, S.; Hinterberger, F.; Jentjens, L.; Mader, W.; Raeth, N. L.; Schmid, H.; Zamani-Meymian, M.-R.; Maier, K.

    2011-10-01

    Ferroelectric lithium niobate crystals offer a great potential for applications in modern optics. To provide powerful optical components, tailoring of key material parameters, especially of the refractive index n and the ferroelectric domain landscape, is required. Irradiation of lithium niobate crystals with accelerated ions causes strong structured modifications in the material. The effects induced by low-mass, high-energy ions (such as 3He with 41 MeV, which are not implanted, but transmit through the entire crystal volume) are reviewed. Irradiation yields large changes of the refractive index Δn, improved domain engineering capability within the material along the ion track, and waveguiding structures. The periodic modification of Δn as well as the formation of periodically poled lithium niobate (PPLN) (supported by radiation damage) is described. Two-step knock-on displacement processes, 3He→Nb and 3He→O causing thermal spikes, are identified as origin for the material modifications.

  15. An automatic and effective parameter optimization method for model tuning

    NASA Astrophysics Data System (ADS)

    Zhang, T.; Li, L.; Lin, Y.; Xue, W.; Xie, F.; Xu, H.; Huang, X.

    2015-05-01

    Physical parameterizations in General Circulation Models (GCMs), having various uncertain parameters, greatly impact model performance and model climate sensitivity. Traditional manual and empirical tuning of these parameters is time consuming and ineffective. In this study, a "three-step" methodology is proposed to automatically and effectively obtain the optimum combination of some key parameters in cloud and convective parameterizations according to a comprehensive objective evaluation metrics. Different from the traditional optimization methods, two extra steps, one determines parameter sensitivity and the other chooses the optimum initial value of sensitive parameters, are introduced before the downhill simplex method to reduce the computational cost and improve the tuning performance. Atmospheric GCM simulation results show that the optimum combination of these parameters determined using this method is able to improve the model's overall performance by 9%. The proposed methodology and software framework can be easily applied to other GCMs to speed up the model development process, especially regarding unavoidable comprehensive parameters tuning during the model development stage.

  16. Direct radiative effect by multicomponent aerosol over China

    SciTech Connect

    Huang, Xin; Song, Yu; Zhao, Chun; Cai, Xuhui; Zhang, Hongsheng; Zhu, Tong

    2015-05-01

    The direct radiative effect (DRE) of multiple aerosol species (sulfate, nitrate, ammonium, black carbon (BC), organic carbon (OC), and mineral aerosol) and their spatiotemporal variations over China were investigated using a fully coupled meteorology–chemistry model (WRF-Chem) for the entire year of 2006. We made modifications to improve model performance, including updating land surface parameters, improving the calculation of transition metal-catalyzed oxidation of SO2, and adding in heterogeneous reactions between mineral aerosol and acid gases. The modified model well reproduced the magnitude, seasonal pattern, and spatial distribution of the measured meteorological conditions, concentrations of PM10 and its components, and aerosol optical depth (AOD). A diagnostic iteration method was used to estimate the overall DRE of aerosols and contributions from different components. At the land surface, all kinds of aerosol species reduced the incident net radiation flux with a total DRE of 10.2 W m-2 over China. Aerosols significantly warm the atmosphere with the national mean DRE of +10.8 W m-2. BC was the leading radiative-heating component (+8.7 W m-2), followed by mineral aerosol (+1.1 W m-2). At the top of the atmosphere (TOA), BC introduced the largest radiative perturbation (+4.5 W m-2), followed by sulfate (-1.4 W m-2). The overall perturbation of aerosols on radiation transfer is quite small over China, demonstrating the counterbalancing effect between scattering and adsorbing aerosols. Aerosol DRE at the TOA had distinct seasonality, generally with a summer maximum and winter minimum, mainly determined by mass loadings, hygroscopic growth, and incident radiation flux.

  17. Radiation damage effects in CZT drift strip detectors

    NASA Astrophysics Data System (ADS)

    Kuvvetli, Irfan; Budtz-Joergensen, Carl; Korsbech, Uffe; Jensen, H. J.

    2003-03-01

    At DSRI, in collaboration with the cyclotron facility at Copenhagen University Hospital, we have performed a study of radiation effects exposing a 2.7 mm thick CZT drift strip detector to 30 MeV protons. The detector characteristics were evaluated after exposure to a number of dose loads in the range from 2*108 to 60*108 p+/cm2. Even for the highest dose loads, which had a dramatic effect on the spectroscopic performance, we were able to recover the detectors after an appropriate annealing procedure. The radiation damage was studied as function of depth inside the detector material. A numerical model that emulates the physical processes of the charge transport in the CZT detector was used to derive the charge trapping parameter , μτe (the product of charge mobility and trapping time) as function of dose. The analysis showed that the electron trapping increased proportional with the proton dose. The radiation contribution to the electron trapping was found to obey the following relation: (μτe)-1rad =(2.5±0.2)*10-7*Φ (V/cm2) with the proton fluence, Φ in p+/cm2. The trapping depth dependence, however, did not agree well the damage profile calculated using the standard Monte Carlo simulations, TRIM for the proton induced radiation effects. The present results suggest that proton induced nuclear reactions contribute significantly to the radiation damage. Further work will elaborate on these effects. The detector energy resolution was investigated as function of proton dose. It was found that the observed degradation is well explained by the decrease of μτe when the fluctuations of the electron path length are taken into account. The proton irradiation produced In meta stable isotopes in the CZT material. Their decay and production yield as function of depth were analyzed.

  18. Transverse effects of microbunch radiative interaction

    SciTech Connect

    Derbenev, Ya.S.; Shiltsev, V.D.

    1996-06-03

    In this article the authors study effects of microbunch cooperative electromagnetic radiation in a bend on transverse beam dynamics. An overtaking radiative interaction between different parts of the bunch results in three major forces variable along the bunch. Longitudinal force leads to energy loss and causes the bunch emittance growth in the bend due to the dispersion effect. Radial force consists of logarithmically large ``Talman`` centrifugal force and smaller centripetal force. Due to general radius-energy dependence in the bend, the ``Talman`` force does not affect beam dynamics while the centripetal force leads to projected emittance growth. Finally, radial and vertical focusing forces lead to trajectory distortions which vary along the bunch. These cooperative forces significantly affect the dynamics of short high-populated bunch in bends.

  19. Radiation Effects in the Space Telecommunications Environment

    SciTech Connect

    Fleetwood, Daniel M.; Winokur, Peter S.

    1999-05-17

    Trapped protons and electrons in the Earth's radiation belts and cosmic rays present significant challenges for electronics that must operate reliably in the natural space environment. Single event effects (SEE) can lead to sudden device or system failure, and total dose effects can reduce the lifetime of a telecommmiications system with significant space assets. One of the greatest sources of uncertainty in developing radiation requirements for a space system is accounting for the small but finite probability that the system will be exposed to a massive solar particle event. Once specifications are decided, standard laboratory tests are available to predict the total dose response of MOS and bipolar components in space, but SEE testing of components can be more challenging. Prospects are discussed for device modeling and for the use of standard commercial electronics in space.

  20. Technology, safety, and costs of decommissioning reference nuclear research and test reactors: sensitivity of decommissioning radiation exposure and costs to selected parameters

    SciTech Connect

    Konzek, G.J.

    1983-07-01

    Additional analyses of decommissioning at the reference research and test (R and T) reactors and analyses of five recent reactor decommissionings are made that examine some parameters not covered in the initial study report (NUREG/CR-1756). The parameters examined for decommissioning are: (1) the effect on costs and radiation exposure of plant size and/or type; (2) the effects on costs of increasing disposal charges and of unavailability of waste disposal capacity at licensed waste disposal facilities; and (3) the costs of and the available alternatives for the disposal of nuclear R and T reactor fuel assemblies.

  1. Advanced CMOS Radiation Effects Testing Analysis

    NASA Technical Reports Server (NTRS)

    Pellish, Jonathan Allen; Marshall, Paul W.; Rodbell, Kenneth P.; Gordon, Michael S.; LaBel, Kenneth A.; Schwank, James R.; Dodds, Nathaniel A.; Castaneda, Carlos M.; Berg, Melanie D.; Kim, Hak S.; Phan, Anthony M.; Seidleck, Christina M.

    2014-01-01

    Presentation at the annual NASA Electronic Parts and Packaging (NEPP) Program Electronic Technology Workshop (ETW). The material includes an update of progress in this NEPP task area over the past year, which includes testing, evaluation, and analysis of radiation effects data on the IBM 32 nm silicon-on-insulator (SOI) complementary metal oxide semiconductor (CMOS) process. The testing was conducted using test vehicles supplied by directly by IBM.

  2. Advanced CMOS Radiation Effects Testing and Analysis

    NASA Technical Reports Server (NTRS)

    Pellish, J. A.; Marshall, P. W.; Rodbell, K. P.; Gordon, M. S.; LaBel, K. A.; Schwank, J. R.; Dodds, N. A.; Castaneda, C. M.; Berg, M. D.; Kim, H. S.; Phan, A. M.; Seidleck, C. M.

    2014-01-01

    Presentation at the annual NASA Electronic Parts and Packaging (NEPP) Program Electronic Technology Workshop (ETW). The material includes an update of progress in this NEPP task area over the past year, which includes testing, evaluation, and analysis of radiation effects data on the IBM 32 nm silicon-on-insulator (SOI) complementary metal oxide semiconductor (CMOS) process. The testing was conducted using test vehicles supplied by directly by IBM.

  3. Radiative transfer effects in primordial hydrogen recombination

    SciTech Connect

    Ali-Haiemoud, Yacine; Hirata, Christopher M.; Grin, Daniel

    2010-12-15

    The calculation of a highly accurate cosmological recombination history has been the object of particular attention recently, as it constitutes the major theoretical uncertainty when predicting the angular power spectrum of cosmic microwave background anisotropies. Lyman transitions, in particular the Lyman-{alpha} line, have long been recognized as one of the bottlenecks of recombination, due to their very low escape probabilities. The Sobolev approximation does not describe radiative transfer in the vicinity of Lyman lines to a sufficient degree of accuracy, and several corrections have already been computed in other works. In this paper, we compute the impact of some radiative transfer effects that were previously ignored, or for which previous treatments were incomplete. First, the effect of Thomson scattering in the vicinity of the Lyman-{alpha} line is evaluated, using a full redistribution kernel incorporated into a radiative transfer code. The effect of feedback of distortions generated by the optically thick deuterium Lyman-{alpha} line blueward of the hydrogen line is investigated with an analytic approximation. It is shown that both effects are negligible during cosmological hydrogen recombination. Second, the importance of high-lying, nonoverlapping Lyman transitions is assessed. It is shown that escape from lines above Ly{gamma} and frequency diffusion in Ly{beta} and higher lines can be neglected without loss of accuracy. Third, a formalism generalizing the Sobolev approximation is developed to account for the overlap of the high-lying Lyman lines, which is shown to lead to negligible changes to the recombination history. Finally, the possibility of a cosmological hydrogen recombination maser is investigated. It is shown that there is no such maser in the purely radiative treatment presented here.

  4. Coloured noise effects on deformation parameters of permanent GPS networks

    NASA Astrophysics Data System (ADS)

    Razeghi, S. M.; Amiri-Simkooei, A. R.; Sharifi, M. A.

    2016-03-01

    Deformation analysis in general and strain analysis in particular using permanent GPS networks require proper analysis of time-series in which all functional effects are taken into consideration and all stochastic effects are captured using an appropriate noise model. This contribution addresses both issues when considering the strain parameters of a GPS network. Estimates of spatial correlation, time correlated noise, and multivariate power spectrum for daily position time-series of the Southern California Integrated GPS Network (SCIGN) stations collected between 1996 and 2011 are obtained. Significant signals with periods of 13.63 d and those related to the GPS draconitic year are identified in these time-series. We aim to assess the effect of a realistic noise model of the series on the uncertainties of the strain parameters including displacements, normal and shear strains, and rotations. For the SCIGN network considered, the following results are highlighted. Contrary to the common belief, the uncertainties of the displacements parameters become smaller when taking a realistic noise model into account. This however was not the case when assessing the noise characteristics of the normal and shear strain, and rotation parameters. The uncertainties increase nearly by a factor of two, in agreement to what is expected. Some of the significant deformation parameters of the white noise model become less significant in case of the realistic noise model.

  5. Space Radiation Effects in Advanced Flash Memories

    NASA Technical Reports Server (NTRS)

    Johnston, A. H.

    2001-01-01

    Memory storage requirements in space systems have steadily increased, much like storage requirements in terrestrial systems. Large arrays of dynamic memories (DRAMs) have been used in solid-state recorders, relying on a combination of shielding and error-detection-and correction (EDAC) to overcome the extreme sensitivity of DRAMs to space radiation. For example, a 2-Gbit memory (with 4-Mb DRAMs) used on the Clementine mission functioned perfectly during its moon mapping mission, in spite of an average of 71 memory bit flips per day from heavy ions. Although EDAC worked well with older types of memory circuits, newer DRAMs use extremely complex internal architectures which has made it increasingly difficult to implement EDAC. Some newer DRAMs have also exhibited catastrophic latchup. Flash memories are an intriguing alternative to DRAMs because of their nonvolatile storage and extremely high storage density, particularly for applications where writing is done relatively infrequently. This paper discusses radiation effects in advanced flash memories, including general observations on scaling and architecture as well as the specific experience obtained at the Jet Propulsion Laboratory in evaluating high-density flash memories for use on the NASA mission to Europa, one of Jupiter's moons. This particular mission must pass through the Jovian radiation belts, which imposes a very demanding radiation requirement.

  6. Estimation of effective hydrogeological parameters in heterogeneous and anisotropic aquifers

    NASA Astrophysics Data System (ADS)

    Lin, Hsien-Tsung; Tan, Yih-Chi; Chen, Chu-Hui; Yu, Hwa-Lung; Wu, Shih-Ching; Ke, Kai-Yuan

    2010-07-01

    SummaryObtaining reasonable hydrological input parameters is a key challenge in groundwater modeling. Analysis of temporal evolution during pump-induced drawdown is one common approach used to estimate the effective transmissivity and storage coefficients in a heterogeneous aquifer. In this study, we propose a Modified Tabu search Method (MTM), an improvement drawn from an alliance between the Tabu Search (TS) and the Adjoint State Method (ASM) developed by Tan et al. (2008). The latter is employed to estimate effective parameters for anisotropic, heterogeneous aquifers. MTM is validated by several numerical pumping tests. Comparisons are made to other well-known techniques, such as the type-curve method (TCM) and the straight-line method (SLM), to provide insight into the challenge of determining the most effective parameter for an anisotropic, heterogeneous aquifer. The results reveal that MTM can efficiently obtain the best representative and effective aquifer parameters in terms of the least mean square errors of the drawdown estimations. The use of MTM may involve less artificial errors than occur with TCM and SLM, and lead to better solutions. Therefore, effective transmissivity is more likely to be comprised of the geometric mean of all transmissivities within the cone of depression based on a precise estimation of MTM. Further investigation into the applicability of MTM shows that a higher level of heterogeneity in an aquifer can induce an uncertainty in estimations, while the changes in correlation length will affect the accuracy of MTM only once the degree of heterogeneity has also risen.

  7. Highly physical penumbra solar radiation pressure modeling with atmospheric effects

    NASA Astrophysics Data System (ADS)

    Robertson, Robert; Flury, Jakob; Bandikova, Tamara; Schilling, Manuel

    2015-10-01

    We present a new method for highly physical solar radiation pressure (SRP) modeling in Earth's penumbra. The fundamental geometry and approach mirrors past work, where the solar radiation field is modeled using a number of light rays, rather than treating the Sun as a single point source. However, we aim to clarify this approach, simplify its implementation, and model previously overlooked factors. The complex geometries involved in modeling penumbra solar radiation fields are described in a more intuitive and complete way to simplify implementation. Atmospheric effects are tabulated to significantly reduce computational cost. We present new, more efficient and accurate approaches to modeling atmospheric effects which allow us to consider the high spatial and temporal variability in lower atmospheric conditions. Modeled penumbra SRP accelerations for the Gravity Recovery and Climate Experiment (GRACE) satellites are compared to the sub-nm/s2 precision GRACE accelerometer data. Comparisons to accelerometer data and a traditional penumbra SRP model illustrate the improved accuracy which our methods provide. Sensitivity analyses illustrate the significance of various atmospheric parameters and modeled effects on penumbra SRP. While this model is more complex than a traditional penumbra SRP model, we demonstrate its utility and propose that a highly physical model which considers atmospheric effects should be the basis for any simplified approach to penumbra SRP modeling.

  8. On the effect of response transformations in sequential parameter optimization.

    PubMed

    Wagner, Tobias; Wessing, Simon

    2012-01-01

    Parameter tuning of evolutionary algorithms (EAs) is attracting more and more interest. In particular, the sequential parameter optimization (SPO) framework for the model-assisted tuning of stochastic optimizers has resulted in established parameter tuning algorithms. In this paper, we enhance the SPO framework by introducing transformation steps before the response aggregation and before the actual modeling. Based on design-of-experiments techniques, we empirically analyze the effect of integrating different transformations. We show that in particular, a rank transformation of the responses provides significant improvements. A deeper analysis of the resulting models and additional experiments with adaptive procedures indicates that the rank and the Box-Cox transformation are able to improve the properties of the resultant distributions with respect to symmetry and normality of the residuals. Moreover, model-based effect plots document a higher discriminatory power obtained by the rank transformation. PMID:22129277

  9. Jupiters radiation belts and their effects on spacecraft

    NASA Technical Reports Server (NTRS)

    Parker, R. H.; Divita, E. L.; Gigas, G.

    1974-01-01

    The effects of electron and proton radiation on spacecraft which will operate in the trapped radiation belts of the planet Jupiter are described, and the techniques and results of the testing and simulation used in the radiation effects program are discussed. Available data from the Pioneer 10 encounter of Jupiter are compared with pre-encounter models of the Jupiter radiation belts. The implications that the measured Jovian radiation belts have for future missions are considered.

  10. 47 CFR 22.867 - Effective radiated power limits.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... Effective radiated power limits. The effective radiated power (ERP) of ground and airborne stations... peak ERP of airborne mobile station transmitters must not exceed 12 Watts. (b) The peak ERP of...