High resolution thermal infrared mapping of Martian channels

Viking Infrared Thermal Mapper (IRTM) high resolution (2 to 5 km) data were compiled and compared to Viking Visual Imaging Subsystem (VIS) data and available 1:5M geologic maps for several Martian channels including Dao, Harmakhis, Mangala, Shalbatana, and Simud Valles in an effort to determine the surface characteristics and the processes active during and after the formation of these channels. Results show a dominance of aeolian processes active in and around the channels. These processes have left materials thick enough to mask any genuine channel deposits. Results also indicate that very comparable Martian channels and their surrounding terrain are blanketed by deposits which are homogeneous in their thermal inertia values. However, optimum IRTM data does not cover the entire Martian surface and because local deposits of high thermal inertia material may not be large enough in areal extent or may be in an unfavorable location on the planet, a high resolution data track may not always occur over these deposits. Therefore, aeolian processes may be even more active than the IRTM data tracts can always show

Impact Absorbent Rapid Manufactured Structures (IARMS)

Rapid Manufacturing (RM) is increasingly becoming a viable manufacturing process due to dramatic advantages that it facilitates in the area of design complexity. Through the exploration of the design freedom afforded by RM, this paper introduces the concept and initial research surrounding Impact Absorbent Rapid Manufactured Structures (IARMS), with an application in sports personal protective equipment (PPE). Designs are based on the cellular structure of foams; the inherent advantages of the cellular structure are used as a basis to create IARMS that have the potential to be optimised for a specific impact absorbent response. The paper provides some initial results from compression testingMechanical Engineerin

Results on Plasma Focusing of High Energy Density Electron and Positron Beams

We present results from the SLAC E-150 experiment on plasma focusing of high energy density electron and, for the first time, positron beams. We also discuss measurements on plasma lens-induced synchrotron radiation, longitudinal dynamics of plasma focusing, and laser- and beam-plasma interactions.Comment: LINAC 2000 paper No. THC13, Monterey, CA. Aug.21-25,2000, 3 pages, 2 figure

Observation of Plasma Focusing of a 28.5 GeV Positron Beam

The observation of plasma focusing of a 28.5 GeV positron beam is reported. The plasma was formed by ionizing a nitrogen jet only 3 mm thick. Simultaneous focusing in both transverse dimensions was observed with effective focusing strengths of order Tesla per micron. The minimum area of the beam spot was reduced by a factor of 2.0 +/- 0.3 by the plasma. The longitudinal beam envelope was measured and compared with numerical calculations

Geochemistry of hydrothermal fluids from the PACMANUS, Northeast Pual and Vienna Woods hydrothermal fields, Manus Basin, Papua New Guinea

Processes controlling the composition of seafloor hydrothermal fluids in silicic back-arc or near-arc crustal settings remain poorly constrained despite growing evidence for extensive magmatic–hydrothermal activity in such environments. We conducted a survey of vent fluid compositions from two contrasting sites in the Manus back-arc basin, Papua New Guinea, to examine the influence of variations in host rock composition and magmatic inputs (both a function of arc proximity) on hydrothermal fluid chemistry. Fluid samples were collected from felsic-hosted hydrothermal vent fields located on Pual Ridge (PACMANUS and Northeast (NE) Pual) near the active New Britain Arc and a basalt-hosted vent field (Vienna Woods) located farther from the arc on the Manus Spreading Center. Vienna Woods fluids were characterized by relatively uniform endmember temperatures (273–285 °C) and major element compositions, low dissolved CO2 concentrations (4.4 mmol/kg) and high measured pH (4.2–4.9 at 25 °C). Temperatures and compositions were highly variable at PACMANUS/NE Pual and a large, newly discovered vent area (Fenway) was observed to be vigorously venting boiling (358 °C) fluid. All PACMANUS fluids are characterized by negative δDH2O values, in contrast to positive values at Vienna Woods, suggesting substantial magmatic water input to circulating fluids at Pual Ridge. Low measured pH (25 °C) values (∼2.6–2.7), high endmember CO2 (up to 274 mmol/kg) and negative δ34SH2S values (down to −2.7‰) in some vent fluids are also consistent with degassing of acid-volatile species from evolved magma. Dissolved CO2 at PACMANUS is more enriched in 13C (−4.1‰ to −2.3‰) than Vienna Woods (−5.2‰ to −5.7‰), suggesting a contribution of slab-derived carbon. The mobile elements (e.g. Li, K, Rb, Cs and B) are also greatly enriched in PACMANUS fluids reflecting increased abundances in the crust there relative to the Manus Spreading Center. Variations in alkali and dissolved gas abundances with Cl at PACMANUS and NE Pual suggest that phase separation has affected fluid chemistry despite the low temperatures of many vents. In further contrast to Vienna Woods, substantial modification of PACMANUS/NE Pual fluids has taken place as a result of seawater ingress into the upflow zone. Consistently high measured Mg concentrations as well as trends of increasingly non-conservative SO4 behavior, decreasing endmember Ca/Cl and Sr/Cl ratios with increased Mg indicate extensive subsurface anhydrite deposition is occurring as a result of subsurface seawater entrainment. Decreased pH and endmember Fe/Mn ratios in higher Mg fluids indicate that the associated mixing/cooling gives rise to sulfide deposition and secondary acidity production. Several low temperature (⩽80 °C) fluids at PACMANUS/NE Pual also show evidence for anhydrite dissolution and water–rock interaction (fixation of B) subsequent to seawater entrainment. Hence, the evolution of fluid compositions at Pual Ridge reflects the cumulative effects of water/rock interaction, admixing and reaction of fluids exsolved from silicic magma, phase separation/segregation and seawater ingress into upflow zones

Arabidopsis uses two gluconeogenic gateways for organic acids to fuel seedling establishment.

Gluconeogenesis is a fundamental metabolic process that allows organisms to make sugars from non-carbohydrate stores such as lipids and protein. In eukaryotes only one gluconeogenic route has been described from organic acid intermediates and this relies on the enzyme phosphoenolpyruvate carboxykinase (PCK). Here we show that two routes exist in Arabidopsis, and that the second uses pyruvate, orthophosphate dikinase (PPDK). Gluconeogenesis is critical to fuel the transition from seed to seedling. Arabidopsis pck1 and ppdk mutants are compromised in seed-storage reserve mobilization and seedling establishment. Radiolabelling studies show that PCK predominantly allows sugars to be made from dicarboxylic acids, which are products of lipid breakdown. However, PPDK also allows sugars to be made from pyruvate, which is a major product of protein breakdown. We propose that both routes have been evolutionarily conserved in plants because, while PCK expends less energy, PPDK is twice as efficient at recovering carbon from pyruvate.We thank the Biotechnology and Biology Sciences Research Council for funding J.M.H. (P18931 and a studentship to B.P.W.) and P.J.E. (BB/G009724/1 and BB/K002147/1), the Isaac Newton Trust and the Max-Planck Gesellschaft for funding and ATC for a CASE studentship to H.M.A.This is the final published version. It first appeared at http://www.nature.com/ncomms/2015/150410/ncomms7659/full/ncomms7659.html

Affective Bias without Hemispheric Competition: Evidence for Independent Processing Resources in Each Cortical Hemisphere

We assessed the extent of neural competition for attentional processing resources in early visual cortex between foveally presented task stimuli and peripheral emotional distracter images. Task-relevant and distracting stimuli were shown in rapid serial visual presentation (RSVP) streams to elicit the steady-state visual evoked potential, which serves as an electrophysiological marker of attentional resource allocation in early visual cortex. A taskrelated RSVP stream of symbolic letters was presented centrally at 15 Hz while distracting RSVP streams were displayed at 4 or 6 Hz in the left and right visual hemifields. These image streams always had neutral content in one visual field and would unpredictably switch from neutral to unpleasant content in the opposite visual field. We found that the steady-state visual evoked potential amplitude was consistently modulated as a function of change in emotional valence in peripheral RSVPs, indicating sensory gain in response to distracting affective content. Importantly, the facilitated processing for emotional content shown in one visual hemifield was not paralleled by any perceptual costs in response to the task-related processing in the center or the neutral image stream in the other visual hemifield. Together, our data provide further evidence for sustained sensory facilitation in favor of emotional distracters. Furthermore, these results are in line with previous reports of a “different hemifield advantage” with lowlevel visual stimuli and are suggestive of independent processing resources in each cortical hemisphere that operate beyond lowlevel visual cues, that is, with complex images that impact early stages of visual processing via reentrant feedback loops from higher order processing areas

Polygenic risk for circulating reproductive hormone levels and their influence on hippocampal volume and depression susceptibility

Altered reproductive hormone levels have been associated with the pathophysiology of depressive disorders and this risk may be imparted by their modulatory effect upon hippocampal structure and function. Currently it is unclear whether altered levels of reproductive hormones are causally associated with hippocampal volume reductions and the risk of depressive disorders. Here, we utilize genome-wide association study (GWAS) summary statistics from a GWAS focusing on reproductive hormones, consisting of 2913 individuals. Using this data, we generated polygenic risk scores (PRS) for estradiol, progesterone, prolactin and testosterone in the European RADIANT cohort consisting of 176 postpartum depression (PPD) cases (100% female, mean age: 41.6 years old), 2772 major depressive disorder (MDD) cases (68.6% female, mean age: 46.9 years old) and 1588 control participants (62.5% female, mean age: 42.4 years old), for which there was also a neuroimaging subset of 111 individuals (60.4% female, mean age: 50.0 years old). Only the best-fit PRS for estradiol showed a significant negative association with hippocampal volume, as well as many of its individual subfields; including the molecular layer and granule cell layer of the dentate gyrus, subiculum, CA1, CA2/3 and CA4 regions. Interestingly, several of these subfields are implicated in adult hippocampal neurogenesis. When we tested the same estradiol PRS for association with case-control status for PPD or MDD there was no significant relationship observed. Here, we provide evidence that genetic risk for higher plasma estradiol is negatively associated with hippocampal volume, but this does not translate into an increased risk of MDD or PPD. This work suggests that the relationship between reproductive hormones, the hippocampus, and depression is complex, and that there may not be a clear-cut pathway for etiology or risk moderation

A magnetically-driven piston pump for ultra-clean applications

A magnetically driven piston pump for xenon gas recirculation is presented. The pump is designed to satisfy extreme purity and containment requirements, as is appropriate for the recirculation of isotopically enriched xenon through the purification system and large liquid xenon TPC of EXO-200. The pump, using sprung polymer gaskets, is capable of pumping more than 16 standard liters per minute (SLPM) of xenon gas with 750 torr differential pressure.Comment: 6 pages, 5 figure