The effect of anisotropic reflectance on imaging spectroscopy of snow properties

How does snow's anisotropic directional reflectance affect the mapping of snow properties from imaging spectrometer data? This sensitivity study applies two spectroscopy models to synthetic images of the spectral hemispherical-directional reflectance factor (HDRF) with prescribed snow-covered area and snow grain size. The MEMSCAG model determines both sub-pixel snow-covered area and the grain size of the fractional snow cover. The Nolin/Dozier model analyzes the ice absorption feature that spans wavelength λ≅1.03 μm to estimate snow grain radius when the pixel is fully snow-covered. Retrievals of subpixel snow-covered area with MEMSCAG are progressively more sensitive to the HDRF as grain size decreases, solar zenith angle increases, and fractional snow cover increases. The model overestimates snow cover in the forward reflectance angles by up to +20% and underestimates it in the backward reflectance angles by as much as −15%. Grain size retrievals from both MEMSCAG and Nolin/Dozier are more sensitive to anisotropy as grain size and solar zenith angle increase. MEMSCAG retrievals of grain size are insensitive to snow-covered area. The largest inferred grain sizes occur around a peak in the backward reflectance angles and the smallest generally occur at the largest view angles in the forward direction. Retrievals of albedo from MEMSCAG and Nolin/Dozier are similarly sensitive to anisotropy, with albedo errors up to 5% for a 30° solar zenith angle and up to 10% at 60°. The albedo differences between the two models are less than 0.015 for all grain sizes and solar zenith angles.     

Time dependence of interface trap formation in MOSFETs followingpulsed irradiation

The time dependence of interference trap (N_it) formation in MOSFETs was studied as a function of gate oxide thickness, oxide growth type, substrate orientation, temperature, and gate bias. Two different N_it formation mechanisms are observed. Most (typically 90%) of the formation, called the late process, occurs slowly at long times (1-10000 s) after the radiation pulse. From a variety of experimental data, it is concluded that the rate of the late process is limited by drift of a radiation-induced positive ion, probably H⁺ , through the gate oxide to the Si-SiO₂ interface where the N_it are formed. A relatively fast, or early, process is responsible for a small percentage of the total N_it formation. The time constant for this process appears to be consistent with hole drift through the oxide     

Site-Specific PEGylation of Therapeutic Proteins

The use of proteins as therapeutics has a long history and is becoming ever more common in modern medicine. While the number of protein-based drugs is growing every year, significant problems still remain with their use. Among these problems are rapid degradation and excretion from patients, thus requiring frequent dosing, which in turn increases the chances for an immunological response as well as increasing the cost of therapy. One of the main strategies to alleviate these problems is to link a polyethylene glycol (PEG) group to the protein of interest. This process, called PEGylation, has grown dramatically in recent years resulting in several approved drugs. Installing a single PEG chain at a defined site in a protein is challenging. Recently, there is has been considerable research into various methods for the site-specific PEGylation of proteins. This review seeks to summarize that work and provide background and context for how site-specific PEGylation is performed. After introducing the topic of site-specific PEGylation, recent developments using chemical methods are described. That is followed by a more extensive discussion of bioorthogonal reactions and enzymatic labeling.     

Low Temperature Water–Gas Shift/Methanol Steam Reforming: Alkali Doping to Facilitate the Scission of Formate and Methoxy C–H Bonds over Pt/ceria Catalyst

Doping Pt/ceria catalysts with the Group 1 alkali metals was found to lead to an important weakening of the C–H bond of formate and methoxy species. This was demonstrated by a shift to lower wavenumbers of the formate and methoxy ν(CH) vibrational modes by DRIFTS spectroscopy. Li and Na-doped Pt/ceria catalysts were tested relative to the undoped catalyst for low temperature water–gas shift and methanol steam reforming using a fixed bed reactor and exhibited higher catalytic activity. Steaming of formate and methoxy species pre-adsorbed on the catalyst surface during in-situ DRIFTS spectroscopy suggested that the species were more reactive for dehydrogenation steps in the catalytic cycle for the Li and Na-doped catalysts relative to undoped Pt/ceria. However, with increasing atomic number over the series of alkali-doped catalysts, the stability of a fraction of the carbonate species was found to increase. This was observed during TPD-MS measurements of the adsorbed CO₂ probe molecule by a systematic increase of a high temperature peak for a fraction of the CO₂ desorbed. This result indicates that alkali-doping is an optimization problem—that is, while improving the dehydrogenation rates of methoxy and formate species, the carbonate intermediate stability increases, making it difficult to liberate the CO₂. Infrared spectroscopy results of CO adsorbed on Pt and ceria suggest that the alkali dopant is located on, and electronically modifies, both the Pt and ceria components. The results not only lend further support to the role that methoxy and formate species play as intermediates in the catalytic mechanisms, but also provide a path forward for improving rates by means other than resorting to higher noble metal loadings.     

Tobacco use in six economically disadvantaged communities in the Dominican Republic.

The Dominican Republic is a tobacco-growing country, and tobacco control efforts there have been virtually nonexistent. This study provides a first systematic surveillance of tobacco use in six economically disadvantaged Dominican Republic communities (two small urban, two peri-urban, two rural; half were tobacco growing). Approximately 175 households were randomly selected in each community (total N = 1,048), and an adult household member reported on household demographics and resources (e.g., electricity), tobacco use and health conditions of household members, and household policies on tobacco use. Poverty and unemployment were high in all communities, and significant gaps in access to basic resources such as electricity, running water, telephones/cell phones, and secondary education were present. Exposure to tobacco smoke was high, with 38.4% of households reporting at least one tobacco user, and 75.5% allowing smoking in the home. Overall, 22.5% reported using tobacco, with commercial cigarettes (58.0%) or self-rolled cigarettes (20.1%) the most commonly used types. Considerable variability in prevalence and type of use was found across communities. Overall, tobacco use was higher in males, illiterate groups, those aged 45 or older, rural dwellers, and tobacco-growing communities. Based on reported health conditions, tobacco attributable risks, and World Health Organization mortality data, it is estimated that at least 2,254 lives could potentially be saved each year in the Dominican Republic with tobacco cessation. Although it is expected that the reported prevalence of tobacco use and health conditions represent underestimates, these figures provide a starting point for understanding tobacco use and its prevalence in the Dominican Republic.     

Mining Text for Expert Witnesses

Text mining is a relatively new research area associated with the creation of novel information resources from electronic text repositories. An expert-witness database based on text from legal, medical, and news documents demonstrates the successful application of text-mining techniques.     

Snow Property Measurements Correlative to Microwave Emission at 35 GHz

Snow microstructure, measured by plane section analysis, and snow wetness, measured by the dilution method, are used to calculate input parameters for a microwave emission model that uses the radiative transfer method. The scattering and absorbing properties are calculated by Mie theory. The effects of different equivalent sphere conversions, adjustments for near-field interference, and different snow wetness characterizations are compared for various snow conditions.     

Single-event effects in resolver-to-digital converters

Single-event effects (SEEs) in two resolver-to-digital converters (RDCs) have been studied using heavy ions and pulsed laser light. The important role of the pulsed laser in establishing single-event upset (SEU) and single-event latchup (SEL) levels prior to accelerator testing is described, as is its role in evaluating the test software and hardware and in gaining a better understanding of the origins of the SEEs. Results from pulsed-laser testing are in quantitative agreement with those from heavy-ion testing: the RDC-19220 is sensitive to both SEUs and SELs whereas the AD2S80 is less sensitive to SEUs and immune to SEL