6,640 research outputs found

    Local‐Regional Similarity in Drylands Increases During Multiyear Wet and Dry Periods and in Response to Extreme Events

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    Climate change is predicted to impact ecosystems through altered precipitation (PPT) regimes. In the Chihuahuan Desert, multiyear wet and dry periods and extreme PPT pulses are the most influential climatic events for vegetation. Vegetation responses are most frequently studied locally, and regional responses are often unclear. We present an approach to quantify correlation of PPT and vegetation responses (as Normalized Difference Vegetation Index [NDVI]) at the Jornada ARS‐LTER site (JRN; 550 km2 area) and the surrounding dryland region (from 0 to 500 km distance; 400,000 km2 study area) as a way to understand regional similarity to locally observed patterns. We focused on fluctuating wet and dry years, multiyear wet or dry periods of 3–4 yr, and multiyear wet periods that contained one or more extreme high PPT pulses or extreme low rainfall. In all but extreme high PPT years, JRN PPT was highly correlated... (See article for full abstract)

    Large-area, wide-angle, spectrally selective plasmonic absorber

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    A simple metamaterial-based wide-angle plasmonic absorber is introduced, fabricated, and experimentally characterized using angle-resolved infrared spectroscopy. The metamaterials are prepared by nano-imprint lithography, an attractive low-cost technology for making large-area samples. The matching of the metamaterial's impedance to that of vacuum is responsible for the observed spectrally selective "perfect" absorption of infrared light. The impedance is theoretically calculated in the single-resonance approximation, and the responsible resonance is identified as a short-range surface plasmon. The spectral position of the absorption peak (which is as high as 95%) is experimentally shown to be controlled by the metamaterial's dimensions. The persistence of "perfect" absorption with variable metamaterial parameters is theoretically explained. The wide-angle nature of the absorber can be utilized for sub-diffraction-scale infrared pixels exhibiting spectrally selective absorption/emissivity.Comment: 7 pages, 6 figures, submitted to Phys. Rev.

    Second-Hand Stress: Neurobiological Evidence for a Human Alarm Pheromone

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    Alarm pheromones are airborne chemical signals, released by an individual into the environment, which transmit warning of danger to conspecifics via olfaction. Using fMRI, we provide the first neurobiological evidence for a human alarm pheromone. Individuals showed activation of the amygdala in response to sweat produced by others during emotional stress, with exercise sweat as a control; behavioral data suggest facilitated evaluation of ambiguous threat

    Effect of potassium application rate and timing on alfalfa yield and potassium concentration and removal in Tennessee

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    Received: December 1st, 2022 ; Accepted: March 15th, 2023 ; Published: April 13th, 2023 ; Correspondence: [email protected] (Medicago sativa L.) is the most important forage crop in the world and potassium plays a significant role in achieving high yields. A field experiment was conducted during the 2012–2014 growing seasons at the University of Tennessee in Springfield. The experimental design was a split-split plot that included four levels of potassium (K) application rates (0, 67.25, 134.50, and 269.00 kg K2O ha-1 ) as the main plots and two K application times (green-up and split) as the subplots, and harvest dates as sub-subplots. The results demonstrated that the dry matter yield (DM) increased significantly with each increment in K application rate up to 134.50 kg K2O ha-1 ; however, the highest K fertilizer application (269 kg K2O ha-1 ) did not result in a significant yield increase relative to 134.50 kg K2O ha-1 , because some luxury consumption of K occurred at the highest rate due to yield leveling off while K2O uptake continued to rise. Potassium concentration and K removal increased with K fertilizer at rates beyond those that maximized yield, indicating luxury consumption of K. The greatest K concentration and removal were recorded at 269 kg K2O ha-1 in all harvest months. The split application was more beneficial than applying full K at the time of green-up due to higher dry matter, K concentration, and K removal in alfalfa. In conclusion, 134.50 kg K2O ha-1 is adequate for maximizing alfalfa yield; split application of K is sometimes superior to the single dose of K fertilizer in alfalfa production

    Silicon Data Acquisition and Front-End Electronics

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    A highly integrated Front-End readout and Data Acquisition scheme for Silicon trackers is presented. In this context, a 16-channel readout chip for Silicon strips detector has been designed in 180nm CMOS technology, having in view a highly multiplexed and sparsified readout global strategy. First results are presented

    Front-End and Readout Electronics for Silicon Trackers at the ILC

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    A highly integrated readout scheme for Silicon trackers making use of Deep Sub-Micron CMOS electronics is presented. In this context,a 16-channel readout chip for Silicon strips detector has been designed in 180nm CMOS technology, each channel comprising a low noise amplifier, a pulse shaper, a sample and hold and a comparator. First results are presented

    The preparation of porcine (Tyr-A14-2H) insulin and its characterization by mass spectrometry

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    The title compound was prepared by catalytic deiodination of (Tyr-A14-3-I) insulin with deuterium gas. Under special conditions (large excess of PdO in CH3OD/D2O at pH 9.2) developed to minimize problems due to poisoning of the catalyst, deuterated insulin was produced in yields of about 35% after purification by reversed phase HPLC. For analysis, the deuterated insulin was digested with V8 protease and was shown by mass spectrometry to have incorporated deuterium to an extent of 96.6 atom %, exclusively in a pentapeptide containing Tyr A14. The title compound should prove useful to those workers studying insulin by mass spectrometry, and use of the method with tritium gas in place of deuterium should permit the preparation of a specifically labelled radioactive insulin analogue which behaves identically to the natural hormon
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