We characterize by different spectroscopic techniques the radiation effects on ytterbium- (Yb) and ytterbium/erbium (Yb/Er)-doped optical fibers. Their vulnerability to the environment of outer space ...is evaluated through passive radiation-induced attenuation (RIA) measurements during and after exposure to 10 keV X-rays, 1 MeV ¿-rays, and 105 MeV protons. These fibers present higher levels of RIA (1000×) than telecommunication-type fibers. Measured RIA is comparable for ¿-rays and protons and is on the order of 1 dB/m at 1.55 ¿ m after a few tenths of a kilorad. Their host matrix codoped with aluminum (Al) and/or phosphorus (P) is mainly responsible for their enhanced radiation sensitivity. Thanks to the major improvements of the Er-doped glass spectroscopic properties in case of Yb-codoping, Yb/Er-doped fibers appear as very promising candidates for outer space applications. In the infrared part of the spectrum, losses in P-codoped Yb-doped fibers are due to the P 1 center that absorbs around 1.6 ¿ m and are very detrimental for the operation of Er-codoped devices in a harsh environment. The negative impact of this defect seems reduced in the case of Al and P-codoping.
Harmful algal blooms (HABs) can adversely impact water quality and threaten human and animal health. People working or living along waterways with prolonged HAB contamination may face elevated toxin ...exposures and breathing complications. Monitoring HABs and potential adverse human health effects is notoriously difficult due to routes and levels of exposure that vary widely across time and space. This study examines the utility of 311 calls to enhance HAB surveillance and monitoring. The study focuses on Cape Coral, FL, USA, located along the banks of the Caloosahatchee River and Estuary and the Gulf of Mexico. The wider study area experienced a prolonged cyanobacteria bloom in 2018. The present study examines the relationship between weekly water quality characteristics (temperature, dissolved oxygen, pH, microcystin-LR) and municipal requests for information or services (algal 311 calls). Each 1 μg/L increase in waterborne microcystin-LR concentrations corresponded with 9% more algal 311 calls (95% confidence interval: 1.03-1.15, p = 0.002). The results suggest water quality monitoring and the 311 dispatch systems may be further integrated to improve public health surveillance.
Low- and high-energy proton experimental data and error rate predictions are presented for many bulk Si and SOI circuits from the 20-90 nm technology nodes to quantify how much low-energy protons ...(LEPs) can contribute to the total on-orbit single-event upset (SEU) rate. Every effort was made to predict LEP error rates that are conservatively high; even secondary protons generated in the spacecraft shielding have been included in the analysis. Across all the environments and circuits investigated, and when operating within 10% of the nominal operating voltage, LEPs were found to increase the total SEU rate to up to 4.3 times as high as it would have been in the absence of LEPs. Therefore, the best approach to account for LEP effects may be to calculate the total error rate from high-energy protons and heavy ions, and then multiply it by a safety margin of 5. If that error rate can be tolerated then our findings suggest that it is justified to waive LEP tests in certain situations. Trends were observed in the LEP angular responses of the circuits tested. Grazing angles were the worst case for the SOI circuits, whereas the worst-case angle was at or near normal incidence for the bulk circuits.
Antenatal glucocorticoid therapy reduces mortality in the preterm infant, but evidence suggests off‐target adverse effects on the developing cardiovascular system. Whether deleterious effects are ...direct on the offspring or secondary to alterations in uteroplacental physiology is unclear. Here, we isolated direct effects of glucocorticoids using the chicken embryo, a model system in which the effects on the developing heart and circulation of therapy can be investigated, independent of effects on the mother and/or the placenta. Fertilized chicken eggs were incubated and divided randomly into control (C) or dexamethasone (Dex) treatment at day 14 out of the 21‐day incubation period. Combining functional experiments at the isolated organ, cellular and molecular levels, embryos were then studied close to term. Chicken embryos exposed to dexamethasone were growth restricted and showed systolic and diastolic dysfunction, with an increase in cardiomyocyte volume but decreased cardiomyocyte nuclear density in the left ventricle. Underlying mechanisms included a premature switch from tissue accretion to differentiation, increased oxidative stress, and activated signaling of cellular senescence. These findings, therefore, demonstrate that dexamethasone treatment can have direct detrimental off‐target effects on the cardiovascular system in the developing embryo, which are independent of effects on the mother and/or placenta.
We characterized the responses of three erbium-doped fibers with slightly different concentrations of rare-earth ions (240-290 ppm) and Al 2 O 3 (7-10 wt.%) during proton and gamma-ray exposures. We ...have simultaneously measured the radiation-induced attenuation (RIA) around the Er 3+ ion pumping wavelength (980 nm) and the associated changes of the Er 3+ emission around 1530 nm. The three erbium-doped fibers show similar radiation responses. All fibers exhibit RIA levels between 9 times 10 -3 and 1.7 times 10 -2 dB m -1 Gy -1 at 980 nm and between 4 times 10 -3 and 1.1 times 10 -2 dB m -1 Gy -1 at 1530 nm. Protons and gamma-rays lead to similar radiation damages, with small differences between the protons of different energies (50 MeV and 105 MeV). Furthermore, we have performed online measurements of the spectral dependence of RIA from 600 to 1600 nm and offline measurements from 1200 to 2400 nm. The three fibers exhibit the same spectral response. Losses decrease monotonically from the visible to the infrared part of the spectrum. We have performed spectral decomposition of these RIA curves with the help of absorption bands previously associated with radiation-induced point defects. Our analysis shows that the main part of the RIA (600-1700 nm) in erbium-doped glass can be explained by the generation of Al-related point defects. The other defects related to the germanium and phosphorus doping of the silica seem to have a lower contribution to the induced losses. The Er 3+ ion properties seem to be mainly unaffected by proton exposure, suggesting a solvation shell around the Er 3+ ion formed by Al 2 O 3 species.
The low-energy proton energy spectra of all shielded space environments have the same shape. This shape is easily reproduced in the laboratory by degrading a high-energy proton beam, producing a ...high-fidelity test environment. We use this test environment to dramatically simplify rate prediction for proton direct ionization effects, allowing the work to be done at high-energy proton facilities, on encapsulated parts, without knowledge of the IC design, and with little or no computer simulations required. Proton direct ionization (PDI) is predicted to significantly contribute to the total error rate under the conditions investigated. Scaling effects are discussed using data from 65-nm, 45-nm, and 32-nm SOI SRAMs. These data also show that grazing-angle protons will dominate the PDI-induced error rate due to their higher effective LET, so PDI hardness assurance methods must account for angular effects to be conservative. We show that this angular dependence can be exploited to quickly assess whether an IC is susceptible to PDI.
The effective linear energy transfer of heavy nuclear recoils (Z/spl ges/3) produced by proton interactions in silicon are calculated for incident proton energies of 50, 100, 200, and 500 MeV. The ...LAHET intranuclear cascade and evaporation code is used to obtain the energy spectra of the nuclear recoils and a Monte Carlo code is then used to follow these recoils as they stop in silicon. The total LET spectra at an observation layer located at a depth of 100 microns in the silicon is calculated. The effectiveness of each proton energy level for single event effects screening of microelectronics is evaluated.
The corruption of floating gate bits due to high-energy protons is analyzed in 41-nm single level NAND Flash memories. Proton-induced upsets at low doses are not negligible in deeply-scaled ...single-level cell Flash memories, due to a combination of direct and indirect ionization effects, which may lead to threshold voltage shifts larger than 2 V. Upsets cross sections are around 10 ^{-19}~{\hbox {cm}}^{2} , and increase with proton energy. Variability of energy deposition in the sensitive volume, the sequence of direct and indirect ionizing events, as well as the threshold voltage and electric field reduction associated with each event were included in a model of proton-induced upsets.
The National Ecological Observatory Network (NEON) intends to monitor mosquito populations across its broad geographical range of sites because of their prevalence in food webs, sensitivity to ...abiotic factors, and relevance for human health. We describe the design of mosquito population sampling in the context of NEON's long‐term continental scale monitoring program, emphasizing the sampling design schedule, priorities, and collection methods. Freely available NEON data and associated field and laboratory samples, will increase our understanding of how mosquito abundance, demography, diversity, and phenology are responding to land use and climate change.
NMOS transistors were irradiated using X-ray, Co-60 gamma, electron, and proton radiation sources. The charge yield was estimated for protons of different energies and electrons and compared to ...values obtained for X-ray and Co-60 irradiations.
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