Radiometric normalization and image mosaic generation of ASTER thermal infrared data: An application to extensive sand sheets and dune fields

Data from the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) have a significant advantage over previous datasets because of the combination of high spatial resolution (15-90 m) and enhanced multispectral capabilities, particularly in the thermal infrared (TIR) atmospheric window (8-12 μm) of the Earth where common silicate minerals are more easily identified. However, the 60 km swath width of ASTER can limit the effectiveness of accurately tracing large-scale features, such as eolian sediment transport pathways, over long distances. The primary goal of this paper is to describe a method for generating a seamless and radiometrically accurate ASTER TIR mosaic of atmospherically corrected radiance and from that, extract surface emissivity for arid lands, specifically, sand seas. The Gran Desierto in northern Sonora, Mexico was used as a test location for the radiometric normalization technique because of past remote sensing studies of the region, its compositional diversity, and its size. A linear approach was taken to transform adjacent image swaths into a direct linear relationship between image acquisition dates. Pseudo-invariant features (PIFs) were selected using a threshold of correlation between radiance values, and change-pixels were excluded from the linear regression used to determine correction factors. The degree of spectral correlation between overlapping pixels is directly related to the amount of surface change over time; therefore, the gain and offsets between scenes were based only on regions of high spectral correlation. The result was a series of radiometrically normalized radiance-at-surface images that were combined with a minimum of image edge seams present. These edges were subsequently blended to create the final mosaic. The advantages of this approach for TIR radiance (as opposed to emissivity) data include the ability to: (1) analyze data acquired on different dates (with potentially very different surface temperatures) as one seamless compositional dataset; (2) perform decorrelation stretches (DCS) on the entire dataset in order to identify and discriminate compositional units; and (3) separate brightness temperature from surface emissivity for quantitative compositional analysis of the surface, reducing seam-line error in the emissivity mosaic. The approach presented here is valid for any ASTER-related study of large geographic regions where numerous images spanning different temporal and atmospheric conditions are encountered.     

The Formation of Calcified Nanospherites during Micropetrosis Represents a Unique Mineralization Mechanism in Aged Human Bone

Osteocytes—the central regulators of bone remodeling—are enclosed in a network of microcavities (lacunae) and nanocanals (canaliculi) pervading the mineralized bone. In a hitherto obscure process related to aging and disease, local plugs in the lacuno‐canalicular network disrupt cellular communication and impede bone homeostasis. By utilizing a suite of high‐resolution imaging and physics‐based techniques, it is shown here that the local plugs develop by accumulation and fusion of calcified nanospherites in lacunae and canaliculi (micropetrosis). Two distinctive nanospherites phenotypes are found to originate from different osteocytic elements. A substantial deviation in the spherites' composition in comparison to mineralized bone further suggests a mineralization process unlike regular bone mineralization. Clearly, mineralization of osteocyte lacunae qualifies as a strong marker for degrading bone material quality in skeletal aging. The understanding of micropetrosis may guide future therapeutics toward preserving osteocyte viability to maintain mechanical competence and fracture resistance of bone in elderly individuals.     

Slag corrosion of dolomite-carbon refractories

Seven industrial doloma refractory samples, coming from three European suppliers, and with different carbon, or graphite, or binder content, are subjected to the action of a slag required for the desulfurization of the steel in the secondary metallurgy at 1600°C. Three tests have been carried out within two induction furnaces. The corrosion depth, at the slag-steel interface, has been measured; the graphite-containing samples display a better resistance than the graphite-free pitch or resin-bonded refractories. Among the graphite-containing samples correlations have been found with the carbon content and with the resistance to oxidation by CO–CO₂ at 1100–1200°C. The slag-refractory interface has been investigated by X-ray diffraction, optical microscopy and electron microprobe analysis; the observed phases are CaO, MgO, Ca₂SiO₄, Ca₃SiO₅ and Ca₁₂Al₁₄O₃₃ (outside graphite and iron). The corrosion mechanism is linked to the reaction of slag with lime, followed by infiltration of the refractory and dispersion of periclase grains in the slag.     

Single-center randomized trial comparing tacrolimus (FK506) and cyclosporine in the prevention of acute myocardial rejection

BACKGROUND: To compare the efficacy and safety of tacrolimus and cyclosporine in heart transplantation, this single-center, prospective, randomized, open-label clinical trial was undertaken. METHODS: Seventy-three adult patients were randomly assigned at the time of transplantation to receive either tacrolimus (n=43) or cyclosporine (n=30) as the primary immunosuppressant. Ten of the 43 patients in the tacrolimus group received the drug intravenously in the perioperative period; all other patients received only oral tacrolimus. RESULTS: With a mean follow-up of 27 months, patient survival rates (tacrolimus 83%, cyclosporine 81%) were similar. Fewer patients experienced acute rejection in the tacrolimus group (79%) than in the cyclosporine group (100%), but the difference was not statistically significant. The number of infections and dialysis and insulin requirements were similar for the 2 treatment groups, but the proportion of patients requiring multidrug antihypertensive regimens was lower in the tacrolimus group (12.5% vs 50.0% at month 6; p=.025). The interpatient variance in pharmacokinetic parameters in a subset of 10 patients was much higher after the first oral dose of tacrolimus than at steady-state (eg, first-dose time at which maximal concentration is reached (t(max)): 3.5+/-2.5h, steady-state t(max): 2.0+/-0.7h), and patients treated with intravenous tacrolimus (n=13) rather than oral tacrolimus (n=30) reached target concentrations faster and with less interpatient variability (eg, at day 0: 9.72+/-10.9 ng/mL intravenously vs 3.31+/-8.1 orally). CONCLUSIONS: Tacrolimus was associated with similar efficacy and safety profiles compared with cyclosporine. The higher interpatient variance in absorption associated with oral tacrolimus during the first few days after transplantation would suggest that intravenous tacrolimus should be used during the perioperative period.     

Individual and situational markers of condom use and sex with nonprimary partners among alcoholic inpatients: Findings from the ATRISK Study.

Alcoholics in treatment have demonstrated increased rates of HIV risk behavior and infection. This study explored individual and situational variables associated with HIV risk behaviors such as condom nonuse and sex with nonprimary partners reported during structured interviews of 802 male and female alcoholic inpatients. Logistic regression analyses indicated that person variables, sexual history variables, and situation variables were independently associated with sexual risk behavior in the most recent episode. Results of paired t tests revealed that participants who had engaged in sex with both primary and nonprimary partners during the previous 6 months reported significantly more frequent alcohol and condom use in situations involving sex with nonprimary partners. Prevention efforts need to target alcoholic inpatients as a group and, within this group, to focus on both high-risk individuals and high-risk situations. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Influence of La and Gd Impurities on the Two Phase Transitions in U0.97Th0.03Be13

The phase diagram of U _1–x Th _x Be ₁₃ exhibits two irregular points at x _C1=1.9 at.% and x _C2=4.55 at.% which mark the endpoints of the concentration range where two phase transitions in specific heat measurements are observed. While it is clear that the upper one belongs to a superconducting phase transition, there are different interpretations for the lower one. It has been suggested that the lower transition involves magnetic correlations which coexist with a single superconducting state or that the lower transition separates two different superconducting states (one or both are probably non-s-wave like). In this scenario the onset of local magnetic order is discussed as being due to an accompanied antiferromagnetic transition or as a product of broken time reversal symmetry. To get more information about the nature of the two superconducting phases, substitution experiments with non-magnetic La and magnetic Gd on the U sites in U _0.97 Th _0.03 Be ₁₃ were performed. From specific heat measurements we argue that the upper transition behaves with La/Gd doping like a conventional s-wave superconductor, whereas the lower transition cannot be brought in line with common pictures of superconducting transitions. Also at the     

Crossover to Fermi-Liquid Behavior at Lowest Temperatures in Pure CeNi2Ge2

We present a low temperature study of the nearly antiferromagnetic heavy Fermion compound CeNi₂Ge₂ including specific heat measurements in magnetic fields up to 13 T, resistivity, magnetization, DC- and AC- susceptibility measurements down to 30 mK. The results show that, although the system is close to a quantum critical point, CeNi₂Ge₂ exhibits Fermi-liquid behavior below approximately 300 mK. At higher temperatures hyperscaling indicates the existence of strong coupling spin fluctuations responsible for the observed non-Fermi-liquid properties.     

The role of echocardiography in preoperative diagnosis of cardiac risk in patients before non-cardiac surgical interventions

Echocardiography is a noninvasive method for cardiac evaluation. A review of the current literature shows that the routine use of echocardiography for assessing perioperative cardiac risk in patients undergoing noncardiac surgery can not be supported. Only patients with suspected relevant heart valve diseases, acute heart failure, cardiomyopathy or condition after heart or heart-lung transplantation may benefit from preoperative echocardiography. In patients with suspected or proven coronary artery disease stress echocardiography offers the most relevant additional information for the anaesthesiologist. However, because of the high financial and personal implications it should be reserved to those patients who are not able to perform a normal stress test. Besides in patients in whom transthoracic echocardiography doesn't offer sufficient information or is not possible transesophageal echocardiography plays only a minor role in preoperative cardiac evaluation.