Temporal and spatial variability in the composition of lavas exposed along the Western Blanco Transform Fault

Author Posting. © American Geophysical Union, 2005. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geochemistry Geophysics Geosystems 6 (2005): Q11009, doi:10.1029/2005GC001026.The northern scarp of the western Blanco Transform (BT) fault zone provides a "tectonic window" into crust generated at an intermediate-rate spreading center, exposing a ~2000 m vertical section of lavas and dikes. The lava unit was sampled by submersible during the Blancovin dive program in 1995, recovering a total of 61 samples over vertical distances of ~1000 m and a lateral extent of ~13 km. Major elements analyses of 40 whole rock samples exhibit typical tholeiitic fractionation trends of increasing FeO*, Na2O, and TiO2 and decreasing Al2O3 and CaO with decreasing MgO. The lava suite shows a considerable range in extent of crystallization, including primitive samples (Mg# 64) and evolved FeTi basalts (FeO>12%;TiO2>2%). Based on rare earth element and trace element data, all of the lavas are incompatible-element depleted normal mid-ocean ridge basalts (N-MORB;La/SmN<1). The geochemical systematics suggest that the lavas were derived from a slightly heterogeneous mantle source, and crystallization occurred in a magmatic regime of relatively low magma flux and/or high cooling rate, consistent with magmatic processes occurring along the present-day southern Cleft Segment. The BT scarp reveals the oceanic crust in two-dimensional space, allowing us to explore temporal and spatial relationships in the horizontal and vertical directions. As a whole, the data do not appear to form regular spatial trends; rather, primitive lavas tend to cluster shallower and toward the center of the study area, while more evolved lavas are present deeper and toward the west and east. Considered within a model for construction of the upper crust, these findings suggest that the upper lavas along the BT scarp may have been emplaced off-axis, either by extensive off-axis flow or off-axis eruption, while the lower lavas represent axial flows that have subsided with time. A calculation based on an isochron model for construction of the upper crust suggests that the Cleft Segment requires at least ~50 ka to build the lower extrusive section, consistent to first order with independent estimates for the construction of intermediate-spreading rate crust.This work was supported by the US National Science Foundation (OCE 02- 22154 to E.K. and J.K. and OCE 9400623 to M.T.)

Resistance exercise training restores bone mineral density in heart transplant recipients

AbstractObjectives. This was a prospective, randomized, controlled study designed to determine the effect of resistance exercise traning on bone metabolism in heart transplant recipients.Background. Osteoporosis frequently complicates heart transplantation. No preventative strategy is generally accepted for glucocorticoid-induced bone loss.Methods. Sixteen male heart transplant recipients were randomly assigned to a resistance exercise group that trained for 6 months (mean [±SD] age 56 ± 6 years) or a control group (mean age 52 ± 10 years) that did not perform resistance exercise. Bone mineral density (BMD) of the total body, femur neck and lumbar spine (L2 to L3) was measured by dual-energy X-ray absorptiometry before and 2 months after transplantation and after 3 and 6 months of resistance exercise or a control period. The exercise regimen consisted of lumbar extension exercise (MedX) performed 1 day/week and variable resistance exercises (Nautilus) performed 2 days/week. Each exercise consisted of one set of 10 to 15 repetitions performed to volitional fatigue.Results. Pretransplantation baseline values for regional BMD did not differ in the control and training groups. Bone mineral density of the total body, femur neck and lumbar vertebra (L2 to L3) were significantly decreased below baseline at 2 months after transplantation in both the control (−3.3 ± 1.3%, − 4.5 ± 2.8%, −12.7 ± 6.2%, respectly) and training groups (−2.9 ± 1.1%, 5.9 ± 3.2%, −14.8 ± 3.1%, respectively). Six months of resistance exercise restored BMD of the whole body, femur neck and lumbar vertebra to within 1%, 1.9% and 3.6% of pretransplantation levels, respectively. Bone mineral density of the control group remained unchanged from the 2-month posttransplantation levels.Conclusions. Within 2 months after heart transplantation, ≈ 3% of whole-body BMD is lost, mostly due to decreases in trabecular bone (−12% to −15% of lumbar vertebra). Six months of resistance exercise, consisting of low back exercise that isolates the lumbar spine and a regimen of variable resistance exercises, restores BMD toward pretransplantation levels. Our results suggest that resistance exercise is osteogenic and should be initiated early after heart transplantation

Rapid Microwave Preparation of Thermoelectric TiNiSn and TiCoSb Half-Heusler Compounds

The 18-electron ternary intermetallic systems TiNiSn and TiCoSb are promising for applications as high-temperature thermoelectrics and comprise earth-abundant, and relatively nontoxic elements. Heusler and half-Heusler compounds are usually prepared by conventional solid state methods involving arc-melting and annealing at high temperatures for an extended period of time. Here, we report an energy-saving preparation route using a domestic microwave oven, reducing the reaction time significantly from more than a week to one minute. A microwave susceptor material rapidly heats the elemental starting materials inside an evacuated quartz tube resulting in near single phase compounds. The initial preparation is followed by a densification step involving hot-pressing, which reduces the amount of secondary phases, as verified by synchrotron X-ray diffraction, leading to the desired half-Heusler compounds, demonstrating that hot-pressing should be treated as part of the preparative process. For TiNiSn, high thermoelectric power factors of 2 mW/mK^2 at temperatures in the 700 to 800 K range, and zT values of around 0.4 are found, with the microwave-prepared sample displaying somewhat superior properties to conventionally prepared half-Heuslers due to lower thermal conductivity. The TiCoSb sample shows a lower thermoelectric figure of merit when prepared using microwave methods because of a metallic second phase

Tethered Spinal Cord due to Thoracic Spinal Cord Lipoma: Minimally Invasive Surgical Management Case Report and Literature Review

An unusual case of a thoracic spine lipoma presenting with profound progressive numbness along with difficult to interpret preoperative imaging is discussed. A uniquely minimally invasive surgical treatment approach with successful outcome and improved neurologic symptoms is presented. A literature review and discussion of the benefits and limitations of a minimally invasive surgical technique are provided. A male presented with several months of progressive bilateral lower extremity numbness that ascended to the mid-thoracic spine. Spine magnetic resonance imaging demonstrated a 9 mm intradural, thoracic spinal mass, which was thought preoperatively to represent an arachnoid cyst with an adhesion or a localized dural ectasia. Subsequent imaging demonstrated a band at the cranial margin of the mass appearing to tether the spinal cord to the dorsal-lateral spinal canal without an arachnoid cyst or osseous defect. Surgical exploration revealed an intradural exophytic, intramedullary fatty mass tethering the spinal cord to the dorsolateral dura. An abnormal patch of dura was observed overlying the fatty attachment but no dural defect was identified. Pathology demonstrated fragments of fibroconnective tissue, scattered mature adipocytes, and entrapped meningeal cells, yielding the diagnosis of a spinal cord lipoma. Follow up imaging demonstrated no residual tethering of the spinal cord

Report from the First Snake Genomics and Integrative Biology Meeting

This report summarizes the proceedings of the 1st Snake Genomics and Integrative Biology Meeting held in Vail, CO USA, 5-8 October 2011. The meeting had over twenty registered participants, and was conducted as a single session of presentations. Goals of the meeting included coordination of genomic data collection and fostering collaborative interactions among researchers using snakes as model systems.Organismic and Evolutionary Biolog

Report from the First Snake Genomics and Integrative Biology Meeting

This report summarizes the proceedings of the 1st Snake Genomics and Integrative Biology Meeting held in Vail, CO USA, 5-8 October 2011. The meeting had over twenty registered participants, and was conducted as a single session of presentations. Goals of the meeting included coordination of genomic data collection and fostering collaborative interactions among researchers using snakes as model systems

MAP Kinase Phosphatase-2 Plays a Critical Role in Response to Infection by Leishmania mexicana

In this study we generated a novel dual specific phosphatase 4 (DUSP4) deletion mouse using a targeted deletion strategy in order to examine the role of MAP kinase phosphatase-2 (MKP-2) in immune responses. Lipopolysaccharide (LPS) induced a rapid, time and concentration-dependent increase in MKP-2 protein expression in bone marrow-derived macrophages from MKP-2+/+ but not from MKP-2−/− mice. LPS-induced JNK and p38 MAP kinase phosphorylation was significantly increased and prolonged in MKP-2−/− macrophages whilst ERK phosphorylation was unaffected. MKP-2 deletion also potentiated LPS-stimulated induction of the inflammatory cytokines, IL-6, IL-12p40, TNF-α, and also COX-2 derived PGE2 production. However surprisingly, in MKP-2−/− macrophages, there was a marked reduction in LPS or IFNγ-induced iNOS and nitric oxide release and enhanced basal expression of arginase-1, suggesting that MKP-2 may have an additional regulatory function significant in pathogen-mediated immunity. Indeed, following infection with the intracellular parasite Leishmania mexicana, MKP-2−/− mice displayed increased lesion size and parasite burden, and a significantly modified Th1/Th2 bias compared with wild-type counterparts. However, there was no intrinsic defect in MKP-2−/− T cell function as measured by anti-CD3 induced IFN-γ production. Rather, MKP-2−/− bone marrow-derived macrophages were found to be inherently more susceptible to infection with Leishmania mexicana, an effect reversed following treatment with the arginase inhibitor nor-NOHA. These findings show for the first time a role for MKP-2 in vivo and demonstrate that MKP-2 may be essential in orchestrating protection against intracellular infection at the level of the macrophage

To arm or to ally? The patron's dilemma and the strategic logic of arms transfers and alliances

How do great powers decide whether to provide arms to or form alliances with client states? This “patron's dilemma” revolves around a decision about how to best provide security to clients without becoming entrapped in unwanted conflicts. Strong commitments worsen the risk of entrapment, whereas weak commitments intensify fears of abandonment. This traditional alliance dilemma can be addressed through the provision of arms and alliances. Great power patrons primarily make such decisions on the basis of two factors: first, the extent to which the patron believes it and its client have common security interests; and second, whether the patron believes that its client has sufficient military capabilities to deter its main adversary without the patron's assistance. Patrons assess the degree of shared threat and the local balances of capabilities in determining whether to support their clients with arms, alliances, or both. As demonstrated in the U.S. provision of security goods to Taiwan and Israel during the Cold War, this strategic logic explains how great powers manage the patron's dilemma

Introduction: reconsidering the region in India: mobilities, actors and development politics

In this introduction to a special issue on ‘Reconsidering the Region in India’, we aim to develop a synthetic and theoretically nuanced account of the multifarious ways in which the idea of region has been imbricated in diverse spatial, political, cultural and socio-economic configurations. We draw from various bodies of anthropological, geographic and historical literature to elaborate on three themes that we believe are central to understanding contemporary processes of region-making in India: trans-regional mobilities and connections; the actors who produce and perform regional imaginaries; and changing regional politics of development.IS

Estimating Grizzly and Black Bear Population Abundance and Trend in Banff National Park Using Noninvasive Genetic Sampling

We evaluated the potential of two noninvasive genetic sampling methods, hair traps and bear rub surveys, to estimate population abundance and trend of grizzly (Ursus arctos) and black bear (U. americanus) populations in Banff National Park, Alberta, Canada. Using Huggins closed population mark-recapture models, we obtained the first precise abundance estimates for grizzly bears ( = 73.5, 95% CI = 64–94 in 2006;  = 50.4, 95% CI = 49–59 in 2008) and black bears ( = 62.6, 95% CI = 51–89 in 2006;  = 81.8, 95% CI = 72–102 in 2008) in the Bow Valley. Hair traps had high detection rates for female grizzlies, and male and female black bears, but extremely low detection rates for male grizzlies. Conversely, bear rubs had high detection rates for male and female grizzlies, but low rates for black bears. We estimated realized population growth rates, lambda, for grizzly bear males ( = 0.93, 95% CI = 0.74–1.17) and females ( = 0.90, 95% CI = 0.67–1.20) using Pradel open population models with three years of bear rub data. Lambda estimates are supported by abundance estimates from combined hair trap/bear rub closed population models and are consistent with a system that is likely driven by high levels of human-caused mortality. Our results suggest that bear rub surveys would provide an efficient and powerful means to inventory and monitor grizzly bear populations in the Central Canadian Rocky Mountains