Study of fluoride corrosion of nickel alloys

Report contains the results of an investigation of the corrosion resistance of nickel and nickel alloys exposed to fluorine, uranium hexafluoride, and volatile fission product fluorides at high temperatures. Survey of the unclassified literature on the subject is included

Increasing the efficiency of pooled estimation with a block covariance structure

Econometrics ; Econometric models

Discrimination of rock classes and alteration products in southwestern Saudi Arabia with computer-enhanced LANDSAT data

Digital LANDSAT MSS data for an area in the southwestern Arabian Shield were computer-enhanced to improve discrimination of rock classes, and recognition of gossans associated with massive sulphide deposits. The test area is underlain by metamorphic rocks that are locally intruded by granites; these are partly overlain by sandstones. The test area further includes the Wadi Wassat and Wadi Qatan massive sulphide deposits, which are commonly capped by gossans of ferric oxides, silica, and carbonates. Color patterns and boundaries on contrast-stretched ratio color composite imagery, and on complementary images constructed using principal component and canonical analyses transformations, correspond exceptionally well to 1:100,000 scale field maps. A qualitative visual comparison of information content showed that the ratio enhancement provided the best overall image for identification of rock type and alteration products

Cortisol awakening response in infants during the first six postnatal months and its relation to birth outcome

Context: The rise of cortisol concentrations after awakening is well documented in adults and children and commonly used as easily accessible marker of hypothalamic-pituitary-adrenal (HPA) reactivity. Objective: The purpose of this study was to demonstrate the existence of a salivary cortisol awakening response (CAR) in infants, and to estimate its association with birth outcome. Setting: The study was conducted in the general community. Participants: Healthy infants up to six months age (N=64). Main outcome measures: Mothers were instructed to collect their infant’s saliva immediately and 30 min after awakening on two days within 45 days, irrespective of awakening time. Information on birth outcome was collected from medical records and questionnaires. Results: Linear mixed models analysis revealed a significant rise of infant salivary cortisol concentrations within 30 minutes after awakening (b=0.128, SE=0.024, t61=5.31, p<0.001), which was quite stable across the two sampling days (r=0.40, p=0.002). The infant CAR was predicted by length of gestation (t61=2.43, p=0.018). Conclusions: The current data demonstrate the existence of a CAR in infants as early as during the first six postnatal months; its relationship with length of gestation supports its usefulness for questions related to developmental neuroscience. Therefore, the infant CAR emerges as non-invasive biomarker of HPA axis dynamics at this early stage of life, with relevance for future research and potential clinical applications

U.S. banks, competition, and the Mexican banking system: how much will NAFTA matter?

Bank competition ; North American Free Trade Agreement ; Mexico

Range Resolution Improvement of Eyesafe Ladar Testbed (ELT) Measurements Using Sparse Signal Deconvolution

The Eyesafe Ladar Test-bed (ELT) is a experimental ladar system with the capability of digitizing return laser pulse waveforms at 2 GHz. These waveforms can then be exploited o-line in the laboratory to develop signal processing techniques for noise reduction, range resolution improvement, and range discrimination between two surfaces of similar range interrogated by a single laser pulse. This paper presents the results of experiments with new deconvolution algorithms with the hoped for gains of improving the range discrimination of the ladar system. The sparsity of ladar returns is exploited to solve the deconvolution problem in two steps. The rst step is to estimate a point target response using a database of measured calibration data. This basic target response is used to construct a dictionary of target responses with dierent delays/ranges. Using this dictionary ladar returns from a wide variety of surface congurations can be synthesized by taking linear combinations. A sparse linear combination matches the physical reality that ladar returns consist of the overlapping of only a few pulses. The dictionary construction process is a pre-processing step that is performed only once. The deconvolution step is performed by minimizing the error between the measured ladar return and the dictionary model while constraining the coecient vector to be sparse. Other constraints such as the non-negativity of the coecients are also applied. The results of the proposed technique are presented in the paper and are shown to compare favorably with previously investigated deconvolution techniques

Twisting of mummified remains around the umbilical cord as a potential risk of delayed twin reduction in the mare

C