Semi-automated feature-tracking of East Antarctic sea ice from Envisat ASAR imagery

While feature tracking of sea ice using cross-correlation methods on pairs of satellite Synthetic Aperture Radar (SAR) images has been extensively carried out in the Arctic, this is not the case in the Antarctic. This is due to the dynamic nature of Antarctic pack ice, its microwave signature, the tendency for SAR swath paths to be poorly aligned with the often narrow sea ice zone around the continent and inadequate satellite sampling. A semi-automated system, known as IPADS (IMCORR [IMageCORRelation] Processing, Analysis and Display System), has been developed to map fast ice and pack ice in Antarctica using multiple pairs of SAR images. The software processing pipeline uses overlapping image pairs which are geocoded and roughly registered using only data contained in the image headers. Next, fast ice maps are rapidly generated using zero motion features located within ocean regions. This also provides precise image registration. Finally, the same image pairs are re-examined for pack ice motion in a slower off-line batch process. The pack and fast ice are identified using a cluster-based search method which compares both location and motion information. Each image pair generates a NetCDF file which adds to a growing database of Antarctic sea ice motion and ice roughness. Five image-pair examples are presented to illustrate the methods used as well as their strengths and limitations. Substantial pack ice motion can often be detected in the marginal ice zone on SAR images only a few days apart.     

Characterizing and improving HIV/AIDS knowledge among cocaine-dependent outpatients.

The present study was an experimental test of efficacy of a brief education intervention for increasing HIV/AIDS knowledge among cocaine-dependent outpatients. Participants were randomly assigned to an HIV/AIDS education intervention (experimental condition) or a sham intervention (control condition). Control participants were subsequently crossed over to the HIV/AIDS education intervention. Experimental participants had higher scores on tests of HIV/AIDS knowledge after receiving the education intervention than did control participants. Further supporting the intervention's efficacy, control participant scores also increased once participants were crossed over and received the education intervention. Scores at follow-up were lower than at postintervention but remained higher than baseline scores. Results support the intervention's efficacy for increasing HIV/AIDS knowledge among cocaine-dependent outpatients. This intervention is brief, inexpensive, and easily implemented. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Specific Polyphenols and Tannins are Associated with Defense Against Insect Herbivores in the Tropical Oak Quercus oleoides

The role of plant polyphenols as defenses against insect herbivores is controversial. We combined correlative field studies across three geographic regions (Northern Mexico, Southern Mexico, and Costa Rica) with induction experiments under controlled conditions to search for candidate compounds that might play a defensive role in the foliage of the tropical oak, Quercus oleoides. We quantified leaf damage caused by four herbivore guilds (chewers, skeletonizers, leaf miners, and gall forming insects) and analyzed the content of 18 polyphenols (including hydrolyzable tannins, flavan-3-ols, and flavonol glycosides) in the same set of leaves using high performance liquid chromatography and mass spectrometry. Foliar damage ranged from two to eight percent per region, and nearly 90% of all the damage was caused by chewing herbivores. Damage due to chewing herbivores was positively correlated with acutissimin B, catechin, and catechin dimer, and damage by mining herbivores was positively correlated with mongolinin A. By contrast, gall presence was negatively correlated with vescalagin and acutissimin B. By using redundancy analysis, we searched for the combinations of polyphenols that were associated to natural herbivory: the combination of mongolinin A and acutissimin B had the highest association to herbivory. In a common garden experiment with oak saplings, artificial damage increased the content of acutissimin B, mongolinin A, and vescalagin, whereas the content of catechin decreased. Specific polyphenols, either individually or in combination, rather than total polyphenols, were associated with standing leaf damage in this tropical oak. Future studies aimed at understanding the ecological role of polyphenols can use similar correlative studies to identify candidate compounds that could be used individually and in biologically meaningful combinations in tests with herbivores and pathogens.     

Characterizing nicotine withdrawal in pregnant cigarette smokers.

Maternal smoking is a leading preventable cause of poor pregnancy outcomes and infant morbidity and mortality. Whereas pregnancy has been thought of as a "window of opportunity" when women are more motivated to change health behaviors such as smoking, only 20% of pregnant women quit smoking upon learning they are pregnant and remain abstinent at the end of the pregnancy. Greater understanding of possible obstacles to smoking during pregnancy, such as nicotine withdrawal, is needed. The symptoms of nicotine withdrawal have been well characterized in nonpregnant smokers, but there has been only 1 report conducted during pregnancy, and that was a retrospective study. The aim of the present study was to characterize nicotine withdrawal and craving in pregnant cigarette smokers. These data were collected as part of prospective clinical trials assessing the efficacy of voucher-based incentives to promote abstinence from cigarette smoking during pregnancy and postpartum. The authors examined results from the Minnesota Nicotine Withdrawal Scale (J. R. Hughes & D. K. Hatsukami, 1998) in 27 abstainers (reported no or very low levels of smoking, which was confirmed biochemically) and 21 smokers (smoked at >80% of their baseline smoking level) during the first 5 days of a cessation attempt. Abstainers reported more impatience, anger, and difficulty concentrating than did smokers. The results also suggest that pregnant smokers generally may have elevated baseline levels of withdrawal, which need to be considered in the design and analysis of future studies. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Artificial star test by real-time video holography for the adjustment of high-numerical-aperture micro-objectives

The star test is a useful tool for fast visual inspection of the aberrations of micro-objectives during final adjustment. One of its most valuable properties is that it permits instantaneous observation of the effect of adjustments of lens groups, for instance, the shifting element during on-axis coma adjustment. Sometimes, however, it is difficult to perform the star test, e.g., in the ultraviolet region, which represents a field of growing interest driven by applications in semiconductor inspection and metrology. In addition, it is difficult to display the point-spread functions with video cameras because of the high dynamic range needed. We present a simple work-around with which to overcome these problems. If an interferometer is available for quantitative wave-front analysis on the production line, the point-spread function may quite easily be computed from an interferogram of the wave front in the back focal plane of a micro-objective. We describe the achievement and application of such a simulated star test in various spectral regions, together with some of its useful applications, including real-time wave-front manipulation.     

Response functions of Si detectors to monoenergetic electrons and positrons in the energy range 0.8–3.5 MeV

The response functions of Si surface barrier detectors (depletion depth: 2 mm, active area: 200 mm²) to monoenergetic electrons and positrons have been measured in the energy range 0.8–3.5 MeV at the Giessen electron linear accelerator. Lower peak-to-total ratios were observed in the positron response functions compared to electrons. The measured response functions were compared with Monte Carlo simulations enabling a separation of the individual contributions to the response function such as: total energy loss, backscattering, transmission, bremsstrahlung emission. A parametrization of the response function for electrons is given, which allows a reliable approximation of the response function in the investigated energy range.     

Feasibility study of a He-magnetometer for neutron electric dipole moment experiments

We report on a ³He-magnetometer capable of detecting tiny magnetic field fluctuations of less than 10⁻¹⁴ T in experiments for measuring the electric dipole moment (EDM) of the neutron. It is based on the Ramsey technique of separated oscillating fields and uses nuclear spin-polarized ³He gas which is stored in two vessels of V10 l in a sandwich-type arrangement around the storage bottle for ultra-cold neutrons (UCN). The gas is polarized by means of optical pumping in a separate, small discharge cell at pressures around 0.5 mbar and is then expanded into the actual magnetometer volume. To detect the polarization of ³He gas at the end of the storage cycle the gas is pumped out by means of an oil-diffusion pump and compressed again into the discharge cell where optical detection of nuclear polarization is used.