Effects Of Radiation Stress Research Articles

Influence of Wave-Induced Radiation Stress on Upper-Layer Ocean Temperature during Typhoons

Radiation stress is defined as the excess momentum caused by ocean waves, which exerts an indispensable impact on the upper-layer ocean conditions as waves pass by. Previous research concentrated on sea surface cooling caused by typhoons. In this paper, we investigated the effect of wave-induced radiation stress on upper-layer ocean temperature (including sea surface temperature (SST) and mixed-layer temperature) under typhoon conditions, as well as the effect of radiation stress on the surface current field. The FVCOM-SWAVE model, which is based on the SWAN model, is used to simulate the response of upper-layer ocean temperature to radiation stress. The simulated results, when validated with Jason-3 satellite and ARGO data, could reproduce the observed phenomenon well in general. Compared to simulations without radiation stress, the bias in the SST results is reduced by about 1 °C if the radiation stress term is taken into account. The mixed-layer depth temperature is expected to be simulated more accurately, with a root mean square error (RMSE) of less than 1.63 °C and a correlation coefficient (COR) of about 0.94. Results show that wave-induced radiation stress enhances the surface current and causes certain deviations to the right so that the upper water diverges and upwelling increases, resulting in a decrease in SST. When the influence of double typhoons is considered, the airflow of LEKIMA(L) rotates from the northwest toward KROSA (R), limiting the development of significant wave height (SWH) and reducing the cooling range. As a result, the present study is of tremendous importance in precisely forecasting the ocean state of the western North Pacific (WNP).

Application of Non-Destructive Condition Monitoring Techniques on Irradiated Low Voltage Unshielded Nuclear Power Cables

In this paper, the effect of radiation stress on the overall degradation of jacket and insulation of low voltage unshielded power cable used in nuclear power plants is discussed. The XLPE insulated and CSPE jacketed cable samples were exposed to a total dose of 400 kGy γ-irradiation with 0.5 kGy/h dose-rate. Dielectric spectroscopy; complex permittivity, and extended voltage response; namely slopes of decay and return voltages were used to study the effect of the irradiation on the cable with an aim to establish the application of these techniques for a non-destructive condition monitoring of the unshielded cables. Shore D hardness was also used to investigate the mechanical characteristic of the cable. It was observed that the radiation stress affected the electrical and mechanical properties of the cable polymeric components i.e. insulation and jacket. The imaginary part of permittivity at low frequency; 100 Hz, the slope of return voltage, and hardness showed a significant increase with absorbed dose showing the effect of irradiation on the jacket and insulating material, as well. A strong correlation was observed between the imaginary part of permittivity at 100 Hz, slopes of return voltage, and hardness. The results show the dielectric measurement techniques are potential non-destructive condition monitoring methods for the unshielded low voltage nuclear power plant power cables for on-site diagnosis.

INFLUENCE OF STOKES DRIFT ON SALT WEDGE INTRUSION EVALUATED USING FULLY-NONLINEAR AND STRONGLY-DISPERSIVE WAVE EQUATIONS

This paper describes the influence of surface waves on salt-wedge intrusion in terms of radiation stress. Radiation stress may increase salt-wedge intrusion when surface waves propagate up a river. This study thus aims to reveal the effect of radiation stress on the distance of salt-wedge intrusion by using fully nonlinear strongly dispersive internal wave equations and three-dimensional numerical computation model, Fantom3D. Fully nonlinear strongly dispersive internal wave model reveals the possibility that large radiation stress is induced near the river mouth and increases the distance of salt-wedge intrusion. Three-dimensional numerical model also demonstrates that there is a significant difference in the intrusion distance by taking into account radiation stress.

Electron-Beam Ionizing Radiation Stress Effects on Mango Fruit (Mangifera indica L.) Antioxidant Constituents before and during Postharvest Storage

The effect of electron-beam ionizing radiation stress and storage on mango fruit antioxidant compounds was evaluated in a dose range of 1-3.1 kGy. Phenolic high-performance liquid chromatography (HPLC) profiles were not affected right after the irradiation process; however, an increase in flavonol constituents was observed after 18 days in storage (3.1 kGy). Total phenolics by the Folin Ciocalteu method and antioxidant capacity (ORAC) were not affected, while reduced ascorbic acid decreased approximately 50-54% during storage (>/=1.5 kGy). No major changes in carotenoid HPLC profiles indicated a delay in ripening of irradiated mangoes (1-3.1 kGy) compared to nonirradiated fruits. However, irradiation dose >/=1.5 kGy induced flesh pitting due to localized tissue death. A summary of the potential roles of reactive oxygen species generated by the irradiation stress on different antioxidant constituents of mango fruits is presented.

Seed number in sunflower as affected by light stress during the floret differentiation interval

Grain number in sunflower responds to variations in radiation over a broad developmental window running from floral initiation through to grain setting, encompassing several sequential processes (i.e. floret differentiation, micro- and megasporogenesis, flowering, fertilization and grain set). We examined the effect of radiation stress during the floret differentiation process (a period of 5–8 days) using shades (80% interception) to reduce radiation incident on field-grown crops. Light stress reduced the integral of the generative area, inflorescence floret number and grain number per plant, without altering grain set. The effects of stress on floret number were mediated by changes in floret differentiation rate rather than by variations in duration of the floret differentiation interval. These responses were linked to changes in total apex area and dry weight, such that floret cross-section and associated dry weight at the end of floral differentiation were reduced by stress. These differences between treatments tended to become smaller towards anthesis. Although stress reduced plant and organ dry weight, there was little change in biomass partitioning to organs other than the apex. There was no measurable compensation between grain size and grain number, so that yield was determined by grain number. We conclude that light stress during the floret differentiation interval can irreversibly reduce grain number and yield in this species.

The effect of radiation stress on gas motions in AGN accretion discs

In this paper we look at one of the effects of irradiation on a warped accretion disc in the context of active galactic nuclei (AGN). A warp will catch a substantial amount of the radiation emitted by the central object. We consider the fluid motions that may arise inside a warped disc when the surface is subject to a radiation stress, and also the net mass flows that result. We find that, to first order, we have a balance of the viscous and Coriolis-type forces. The radial radiation stress causes outward motion of the surface layer, but only the azimuthal Poynting–Robertson drag leads to an increase in the net accretion rate. We investigate the distribution of the velocity perturbations and find them to be significant in determining the local structure of the disc. An unexpected result is that the picture changes significantly when we take into account the periodic illumination of the warped disc. A type of resonance at the local Keplerian rotation frequency causes a flow that penetrates the whole thickness of the disc; these flows are faster than the flows due to unchanging illumination. They totally dominate the induced flows in terms of sheer mass, but significant impact on disc structure still occurs only near the surface, where velocity perturbations typically go up to some kilometres per second.

Acoustic Streaming and other Radiation Stress Effects

Acoustic Streaming and other Radiation Stress Effects

Synergetic effects of radiation stress and hot-carrier stress on the current gain of npn bipolar junction transistors

The combined effects of ionizing radiation and hot-carrier stress on the current gain of npn bipolar junction transistors were investigated. The analysis was carried out experimentally by examining the consequences of interchanging the order in which the two stress types were applied to identical transistors which were stressed to various levels of damage. The results indicate that the hot-carrier response of the transistor is improved by radiation damage, whereas hot-carrier damage has little effect on subsequent radiation stress. Characterization of the temporal progression of hot-carrier effects revealed that hot-carrier stress acts initially to reduce excess base current and improve current gain in irradiated transistors. PISCES simulations show that the magnitude of the peak electric-field within the emitter-base depletion region is reduced significantly by net positive oxide charges induced by radiation. The interaction of the two stress types is explained in a qualitative model based on the probability of hot-carrier injection determined by radiation damage and on the neutralization and compensation of radiation-induced positive oxide charges by injected electrons. The results imply that a bound on damage due to the combined stress types is achieved when hot-carrier stress precedes any irradiation. >

Some inhibitory effects of radiation stress on tomato fruit ripening

AbstractDetached tomato (Lycopersicon esculentum Mill. cv. Vendor) fruit exposed to 650 W m−2 radiation from incandescent lamps for 1.5 or 4 h developed visible injury during subsequent storage. In tissues directly exposed to the radiation, ascorbic acid content was decreased and lycopene accumulation and protopectin solubilisation were blocked. For intact fruit, the respiratory climacteric was depressed, but ethylene production was enhanced following the radiation stress. Radiation injury blocks both the initiation and the progress of ripening.

SHOALING SURFACE GRAVITY WAVES: A BISPECTRAL ANALYSIS

Nonlinearities (wave-wave interactions) play a vital role in many aspects of nearshore dynamics, such as wave shoaling and breaking, wave forces, wave-current interactions, radiation stress effects, and sediment transport. The importance of nonlinearities in the nearshore region cannot be overemphasized. At present, however, there is no wave theory that adequately accounts for these interactions, and field observations are sparse. Herein, the bispectrum is used to investigate the temporal and spatial variation of wave-wave interactions in cross-shore velocity for shoaling surface gravity waves in several nearshore environments. The implications for sediment movement of the sign of the observed wavewave interactions for both the real part of the velocity bispectrum (which is related to the skewness of the horizontal asymmetry) and the imaginary part of the velocity bispectrum (which is related to the skewness of the temporal derivative) are discussed. A parameterization is given for the amplitude and phase evolution of the self-self sum interactions within the wind-wave peak for both planar and barred nearshore topography. The results of this paper underline the potential importance of infragravity wave energy in determining nearshore morphology.

Studies of a Simple Laboratory Microecosystem: Effects of Stress

Inocula from an established microcosm were subjected to acute gamma radiation levels of 105 and 106 rads. Microcosms developed from these inocula were sampled through the 40—day successional period to determine effects of radiation stress. Chlorophyll "a" content, biomass, and community metabolism were measured. Significant reduction in chlorophyll "a" was found when each treatment level was compared to its control. Biomass was significantly reduced throughout succession for both treatment levels except for the last sample of 106 rad microcosms. Net productivity and nighttime respiration varied similarly and were significantly reduced during early succession at both treatment levels. Comparison of treatment effects revealed that the 105 rad level microcosms responded to the stress with a greater reduction in parameters measured than the 106. Explanation of this phenomenon may lie in inhibitory interactions among microcosm components at 105 rads. Elimination of certain species at 106 rads may have limited this interaction. The action of radiation at the community level was similar to that of other forms of stress in that radiation can differentially affect the organisms comprising a community and subsequently change community structure. The present study illustrates the idea that stress changes species dominants and succession. In addition, it emphasizes the significance of changes in interactions among community components when a community is stressed.