Maximum A Posteriori Resampling of Noisy, Spatially Correlated Data

In any geologic application, noisy data are sources of consternation for researchers, inhibiting interpretability and marring images with unsightly and unrealistic artifacts. Filtering is the typical solution to dealing with noisy data. However, filtering commonly suffers from ad hoc (i.e., uncalibrated, ungoverned) application. We present here an alternative to filtering: a newly developed method for correcting noise in data by finding the “best” value given available information. The motivating rationale is that data points that are close to each other in space cannot differ by “too much,” where “too much” is governed by the field covariance. Data with large uncertainties will frequently violate this condition and therefore ought to be corrected, or “resampled.” Our solution for resampling is determined by the maximum of the a posteriori density function defined by the intersection of (1) the data error probability density function (pdf) and (2) the conditional pdf, determined by the geostatistical kriging algorithm applied to proximal data values. A maximum a posteriori solution can be computed sequentially going through all the data, but the solution depends on the order in which the data are examined. We approximate the global a posteriori solution by randomizing this order and taking the average. A test with a synthetic data set sampled from a known field demonstrates quantitatively and qualitatively the improvement provided by the maximum a posteriori resampling algorithm. The method is also applied to three marine geology/geophysics data examples, demonstrating the viability of the method for diverse applications: (1) three generations of bathymetric data on the New Jersey shelf with disparate data uncertainties; (2) mean grain size data from the Adriatic Sea, which is a combination of both analytic (low uncertainty) and word-based (higher uncertainty) sources; and (3) side-scan backscatter data from the Martha\u27s Vineyard Coastal Observatory which are, as is typical for such data, affected by speckle noise. Compared to filtering, maximum a posteriori resampling provides an objective and optimal method for reducing noise, and better preservation of the statistical properties of the sampled field. The primary disadvantage is that maximum a posteriori resampling is a computationally expensive procedure

Studies of effects on optical components and sensors: LDEF experiments AO-147 (ERB components) and S-0014 (APEX)

Some additional results of testing of optical filters and window materials and thermopile sensors of the two experiments are included. The Advanced Photovoltaic Experiment (APEX) interference filters exhibited much greater degradation in space than the ERB filters. The adhesion of the Indium washers to the APEX interference filters is reported

Perceptions of International Students and University Personnel of Cultural Adjustment Problems at Two Private Universities

The influx of international students studying at United States colleges and universities during the past five decades has presented many challenges related to accommodating the needs of these “special” students. In the early 1950s, fewer than 40,000 international students were enrolled within the higher education system of the U.S.; today that number has grown to more than 490,000 students. The problems confronted by these students are both numerous and complex. University personnel often address these problems by developing specific programs designed to meet the needs of the international students at their university. However, the perceptions of these problems by international students, faculty, and staff differ in important ways. To explore these problems in more detail, this study first collected data from 215 international students and 44 university personnel at one liberal arts university and a doctoral comprehensive university in the United States, both religiously affiliated, through the use of a well-established survey instrument. The responses from these two groups were then compared and analyzed through the use of paired sample t-tests in 11 possible areas of concern, ranging from health services to financial aid. After their responses were compared and analyzed, multiple regression analysis was then used to examine the extent to which the variation in their responses could be explained by a number of demographic factors. The findings of the study revealed that the university personnel on both campuses significantly overstated the problems of international students, although both groups considered the problems to be relatively minor. Since it was thought that the students would consider their problems more serious than the university personnel, this suggests that the two universities are responding appropriately to a large majority of the problems faced by international students on their campuses. When the student responses were examined in detail, country of origin time at the university, and the particular university attended proved to be significant factors in explaining the variance in the student responses, while gender, marital status, and major field of study did not

Paper Session III-B - Space Exploration Initiative Logistics Support - Lessons from the DoD

A mission as complex as the Space Exploration Initiative (SEI) cannot succeed without adhering to sound principles in the planning, development, and execution of logistics support for the exploration crews and their mission equipment. While much attention will focus upon the development of reliable, robust, heavy lift launch vehicles, and scientific, technological breakthroughs for SEI, of equal concern is the supportability and sustainability of systems designed for mission operations and crew life support on the lunar and Martian surfaces

Metformin, lipids and atherosclerosis prevention

Purpose of review: We provide an overview of recent publications that extend clinically relevant knowledge relating to metformin's effects on lipids and atherosclerotic vascular disease and/or provide insights into the drug's mechanisms of action on the heart and vasculature. Recent findings: We focus on original research in humans or in human tissues. Several recently completed randomized clinical trials have reported effects of metformin on surrogate measures of atherosclerotic vascular disease, including carotid–intima media thickness, vascular reactivity and calcification in people with Type 1 (T1D) and Type 2 (T2D) diabetes as well as nondiabetic dysglycaemia. In addition, observational studies have provided novel insights into the mechanisms of metformin's effects on carotid plaque, monocytes/macrophages, vascular smooth muscle and endothelial cells, including via 5’-adenosine monophosphate-activated protein kinase (AMPK) activation. Summary: Recent trials based on surrogate outcome measures have provided further data suggesting protective effects of metformin against vascular disease in youth and adults with Type 1 diabetes, as well as in adults with prediabetes and Type 2 diabetes. In parallel, human tissue and cell studies have provided new insights into pleiotropic effects of metformin and suggest novel drug targets. As metformin is an inexpensive agent with an established safety profile, larger scale clinical trials based on hard clinical outcomes [cardiovascular disease (CVD) events] are now indicated