Dune field pattern formation and recent transporting winds in the Olympia Undae Dune Field, north polar region of Mars

High-Resolution Imaging Science Experiment (HiRISE) imagery of the central Olympia Undae Dune Field in the north polar region of Mars shows a reticulate dune pattern consisting of two sets of nearly orthogonal dune crestlines, with apparent slipfaces on the primary crests, ubiquitous wind ripples, areas of coarse-grained wind ripples, and deflated interdune areas. Geomorphic evidence and dune field pattern analysis of dune crest length, spacing, defect density, and orientation indicates that the pattern is complex, representing two constructional generations of dunes. The oldest and best-organized generation forms the primary crestlines and is transverse to circumpolar easterly winds. Gross bed form-normal analysis of the younger pattern of crestlines indicates that it emerged with both circumpolar easterly winds and NE winds and is reworking the older pattern. Mapping of secondary flow fields over the dunes indicates that the most recent transporting winds were from the NE. The younger pattern appears to represent an influx of sediment to the dune field associated with the development of the Olympia Cavi reentrant, with NE katabatic winds channeling through the reentrant. A model of the pattern reformation based upon the reconstructed primary winds and resulting secondary flow fields shows that the development of the secondary pattern is controlled by the boundary condition of the older dune topography

Study of 5 and 10 mm thick CZT strip detectors

We report progress in the study of 5 and 10 mm thick CZT strip detectors featuring orthogonal coplanar anode contacts. This novel anode geometry combines the advantages of pixel detectors with those of double-sided strip detectors. Like pixel detectors, these are electron-only devices that perform well as hard x-ray and y-ray spectrometers and imagers even in the thicker configurations required for reasonable detection efficiency at 1 MeV. Like double-sided strip detectors in an N x N configuration, these detectors require only 2N readout channels to form N2 “pixels”. Unlike doublesided strip detectors, all signal contacts for spectroscopy and 3- d imaging are formed on one detector surface. Polymer flip chip bonding to a ceramic substrate is employed resulting in a rugged and compact detector assembly. Prototype detector modules 5 mm thick have been fabricated and tested. Prototype modules, 10 mm thick, are currently in procurement. Measurements confirm these devices are efficient detectors throughout their volume. Sub-millimeter position resolution and energy resolution (FWHM) better than 3% at 662 keV and 15% at 60 keV throughout the detector volume are demonstrated. Options for processing the signals from the non-collecting anode strip contacts are discussed. Results from tests of one prototype circuit are presented. We also report on detector simulation studies aimed at defining an optimum geometry for the anode contacts and at determining optimum operating conditions and the requirements of the signal processing electronics

Energy and position resolution of a CdZnTe gamma-ray detector with orthogonal coplanar anodes

We report on the simulation, construction and performance of prototype CZT imaging detectors employing orthogonal coplanar anodes. These detectors employ a novel electrode geometry with non-collecting anode strips in 1D and collecting anode pixels, interconnected in rows, in the orthogonal dimensions. These detectors retain the spectroscopic and detection efficiency advantages of single carried charge sensing devices as well as the principal advantage of conventional strip detectors with orthogonal anode and cathode strips, i.e. an N X N array of imagin pixels are realized with only 2N electronic channels. Charge signals induced on the various electrodes of a prototype detector with 8 X 8 unit cells are in good agreement with the simulations. The position resolution is about 1 mm in the direction perpendicular to the pixel lines while it is of the order of 100 micrometers in the other direction. Energy resolutions of 0.9 percent at 662 keV, 2.6 percent at 122 keV and 5.7 percent at 60 keV have been obtained at room temperature

Aspects of Common Eider Nesting Ecology in Labrador

The status, distribution, and nesting ecology of common eiders (Somateria mollissima) breeding in Labrador are not well known. This study is an initial effort to improve understanding of the nesting ecology of eiders on the Labrador coast, a zone of intergradation between the northern (S. m. borealis) and American (S. m. dresseri) subspecies of common eider. During 1998 and 1999, 187 islands were surveyed for nesting eiders at four sites (from north to south: Nain, Hopedale, Makkovik, St. Peter’s Bay) along 750 km of the coast. Nest initiation dates (calculated by candling eggs) ranged over a four- to five-week period and were positively associated with latitude: the earliest mean initiation date (5 June) was in St. Peter’s Bay in the south and the latest (27 June) at Nain in the north. Mean clutch size ranged from 3.5 to 4.2 and varied by area and year; eiders nesting in Nain had the smallest clutches. In 1999, the highest nest density (49.8 nests/ha) was observed in Nain and the lowest (3.9 nests/ha) in Makkovik. In some cases, we used boat surveys to assess eider presence and absence and found it to be a reliable method; this search technique could be beneficial to researchers working in remote locations where operational costs are high.On connaît mal le statut, la distribution et l’écologie de nidification de l’eider à duvet (Somateria mollissima) qui se reproduit au Labrador. Cette étude représente un premier pas vers une meilleure compréhension de l’écologie de nidification de l’eider sur la côte du Labrador, une zone de chevauchement entre la sous-espèce du nord (S. m. borealis) et celle américaine (S. m. dresseri) de l’eider à duvet. Durant 1998 et 1999, on a cherché des eiders nicheurs dans 187 îlots à quatre endroits (du nord au sud: Nain, Hopedale, Makkovik, baie de St. Peter’s) répartis sur 750 km de rivage. Les dates du début de la couvaison (calculées en mirant les oeufs) s’étalaient sur une période de quatre à cinq semaines et étaient associées positivement à la latitude: c’est dans la baie de St. Peter’s dans le sud qu’on a observé la date moyenne du début de la couvaison la plus précoce (5 juin), et à Nain dans le nord, la plus tardive (27 juin). La taille moyenne de la couvée allait de 3,5 à 4,2 et variait selon l’endroit et l’année; les eiders qui nichaient à Nain avaient les plus petites couvées. En 1999, la plus forte densité de nids (49,8 nids/ha) a été observée à Nain et la plus faible (3,9 nids/ha), à Makkovik. Dans certains cas, on a utilisé des relevés effectués à partir d’embarcations pour établir la présence et l’absence d’eiders, méthode qui s’est avérée fiable; cette technique de recherche pourrait être bénéfique aux chercheurs travaillant dans des lieux éloignés où les coûts d’opération sont élevés

The Relationship Between Physical Characteristics and Maximal Strength in Men Practicing the Back Squat, the Bench Press and the Deadlift

International Journal of Exercise Science 13(4): 281-297, 2020. This study was designed to quantify the relationships between physical characteristics and maximal strength in the back squat, the bench press and the deadlift on powerlifters and football players.Eighteen male junior drug-tested classic powerlifters and seventeen NCAA Division II American football players’ anthropometric measurements were taken to compare them with maximal strength results from either a powerlifting meet or testing from their supervised strength and conditioning program. Pearson’s bivariate correlations analysis revealed (statistical significance was set at

Ferrous Iron Is a Significant Component of Bioavailable Iron in Cystic Fibrosis Airways

Chronic, biofilm-like infections by the opportunistic pathogen Pseudomonas aeruginosa are a major cause of mortality in cystic fibrosis (CF) patients. While much is known about P. aeruginosa from laboratory studies, far less is understood about what it experiences in vivo. Iron is an important environmental parameter thought to play a central role in the development and maintenance of P. aeruginosa infections, for both anabolic and signaling purposes. Previous studies have focused on ferric iron [Fe(III)] as a target for antimicrobial therapies; however, here we show that ferrous iron [Fe(II)] is abundant in the CF lung (~39 µM on average for severely sick patients) and significantly correlates with disease severity (ρ = −0.56, P = 0.004), whereas ferric iron does not (ρ = −0.28, P = 0.179). Expression of the P. aeruginosa genes bqsRS, whose transcription is upregulated in response to Fe(II), was high in the majority of patients tested, suggesting that increased Fe(II) is bioavailable to the infectious bacterial population. Because limiting Fe(III) acquisition inhibits biofilm formation by P. aeruginosa in various oxic in vitro systems, we also tested whether interfering with Fe(II) acquisition would improve biofilm control under anoxic conditions; concurrent sequestration of both iron oxidation states resulted in a 58% reduction in biofilm accumulation and 28% increase in biofilm dissolution, a significant improvement over Fe(III) chelation treatment alone. This study demonstrates that the chemistry of infected host environments coevolves with the microbial community as infections progress, which should be considered in the design of effective treatment strategies at different stages of disease. IMPORTANCE: Iron is an important environmental parameter that helps pathogens thrive in sites of infection, including those of cystic fibrosis (CF) patients. Ferric iron chelation therapy has been proposed as a novel therapeutic strategy for CF lung infections, yet until now, the iron oxidation state has not been measured in the host. In studying mucus from the infected lungs of multiple CF patients from Europe and the United States, we found that ferric and ferrous iron change in concentration and relative proportion as infections progress; over time, ferrous iron comes to dominate the iron pool. This information is relevant to the design of novel CF therapeutics and, more broadly, to developing accurate models of chronic CF infections

A direct association between amber and dinosaur remains provides paleoecological insights

This work is licensed under a Creative Commons Attribution 4.0 International License.Hadrosaurian dinosaurs were abundant in the Late Cretaceous of North America, but their habitats remain poorly understood. Cretaceous amber is also relatively abundant, yet it is seldom found in direct stratigraphic association with dinosaur remains. Here we describe an unusually large amber specimen attached to a Prosaurolophus jaw, which reveals details of the contemporaneous paleoforest and entomofauna. Fourier-transform Infrared spectroscopy and stable isotope composition (H and C) suggest the amber formed from resins exuded by cupressaceous conifers occupying a coastal plain. An aphid within the amber belongs to Cretamyzidae, a Cretaceous family suggested to bark-feed on conifers. Distinct tooth row impressions on the amber match the hadrosaur’s alveolar bone ridges, providing some insight into the taphonomic processes that brought these remains together

Entropic Tension in Crowded Membranes

Unlike their model membrane counterparts, biological membranes are richly decorated with a heterogeneous assembly of membrane proteins. These proteins are so tightly packed that their excluded area interactions can alter the free energy landscape controlling the conformational transitions suffered by such proteins. For membrane channels, this effect can alter the critical membrane tension at which they undergo a transition from a closed to an open state, and therefore influence protein function \emph{in vivo}. Despite their obvious importance, crowding phenomena in membranes are much less well studied than in the cytoplasm. Using statistical mechanics results for hard disk liquids, we show that crowding induces an entropic tension in the membrane, which influences transitions that alter the projected area and circumference of a membrane protein. As a specific case study in this effect, we consider the impact of crowding on the gating properties of bacterial mechanosensitive membrane channels, which are thought to confer osmoprotection when these cells are subjected to osmotic shock. We find that crowding can alter the gating energies by more than $2\;k_BT$ in physiological conditions, a substantial fraction of the total gating energies in some cases. Given the ubiquity of membrane crowding, the nonspecific nature of excluded volume interactions, and the fact that the function of many membrane proteins involve significant conformational changes, this specific case study highlights a general aspect in the function of membrane proteins.Comment: 20 pages (inclduing supporting information), 4 figures, to appear in PLoS Comp. Bio

Thermal Emission of WASP-14b Revealed with Three Spitzer Eclipses

Exoplanet WASP-14b is a highly irradiated, transiting hot Jupiter. Joshi et al. calculate an equilibrium temperature Teq of 1866 K for zero albedo and reemission from the entire planet, a mass of 7.3 +/- 0.5 Jupiter masses and a radius of 1.28 +/- 0.08 Jupiter radii. Its mean density of 4.6 g/cm3 is one of the highest known for planets with periods less than 3 days. We obtained three secondary eclipse light curves with the Spitzer Space Telescope. The eclipse depths from the best jointly fit model are $0.224\%$ +/- $0.018\%$ at 4.5 {\mu}m and $0.181\%$ +/- $0.022\%$ at 8.0 {\mu}m. The corresponding brightness temperatures are 2212 +/- 94 K and 1590 +/- 116 K. A slight ambiguity between systematic models suggests a conservative 3.6 {\mu}m eclipse depth of $0.19\%$ +/- $0.01\%$ and brightness temperature of 2242 +/- 55 K. Although extremely irradiated, WASP-14b does not show any distinct evidence of a thermal inversion. In addition, the present data nominally favor models with day night energy redistribution less than $~30\%$. The current data are generally consistent with oxygen-rich as well as carbon-rich compositions, although an oxygen-rich composition provides a marginally better fit. We confirm a significant eccentricity of e = 0.087 +/- 0.002 and refine other orbital parameters.Comment: 16 pages, 16 figure