1,307 research outputs found

    Evolution of the diets of Australian Possums (Marsupialia: Phalangeriformes) from the Etadunna Formation in the Lake Eyre Basin, South Australia

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    The Lake Eyre Basin in South Australia holds Australia’s oldest known fossil marsupials representing both extant and extinct families in the Etadunna Formation, a formation that spans nearly two million years from 23.3 to 25 MA. During that two-million-year period, the terrestrial herbivorous marsupials present in the area underwent a dramatic transition both taxonomically and dentally, likely brought on by a changing environment caused by a warming climate. However, it is unknown whether a similar change occurred to the marsupials like possums that live up in the canopy. Understanding this could help determine how extensively this change in the environment affected the marsupials in this region. In Australian possums, the third premolar in particular shows the greatest morphological diversity and is therefore the best indicator of the possum’s dietary niche. These premolars can be wide and bladed to small and conical to tall and canine-like. The size and shape of third premolars can be correlated with molar shape to determine diet through Kendall’s ranked correlation. Additionally, a microwear analysis can help further narrow down possible dietary niches. Microwear refers to the microscopic pits and grooves in teeth created by food substrate grinding against the teeth during chewing. The ratio of scratches to pits is determined by the physical qualities of the food, including its hardness, toughness, plasticity, and strength. The third premolars in possums provide large occlusal surfaces, making them ideal candidates for studying microwear. Areas of 0.6 mm x 0.6 mm on the occlusal surfaces of the upper and lower third premolars were studied. After the dietary niches of the possum species were determined, these niches were charted based on when in the formation each of the different species lived to see if the dietary niches of the possums changed over time. The result showed that the seven different families of possums followed one of four trends. The families of Pseudocheiridae and Ektopodontidae experienced minimal changes over the course of this two-million-year period. Burramyidae experienced a taxonomic and dietary transition during this time. Miralinidae and Pilkipildridae went through a local extirpation. Finally, there was not enough data to determine changes in the Phalangeridae and Petauroidae families during this time

    The Deep Subsurface Biosphere in Igneous Ocean Crust: Frontier Habitats for Microbiological Exploration

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    We discuss ridge flank environments in the ocean crust as habitats for subseafloor microbial life. Oceanic ridge flanks, areas far from the magmatic and tectonic influence of seafloor spreading, comprise one of the largest and least explored microbial habitats on the planet. We describe the nature of selected ridge flank crustal environments, and present a framework for delineating a continuum of conditions and processes that are likely to be important for defining subseafloor microbial "provinces." The basis for this framework is three governing conditions that help to determine the nature of subseafloor biomes: crustal age, extent of fluid flow, and thermal state. We present a brief overview of subseafloor conditions, within the context of these three characteristics, for five field sites where microbial studies have been done, are underway, or have been proposed. Technical challenges remain and likely will limit progress in studies of microbial ridge flank ecosystems, which is why it is vital to select and design future studies so as to leverage as much general understanding as possible from work focused at a small number of sites. A characterization framework such that as presented in this paper, perhaps including alternative or additional physical or chemical characteristics, is essential for achieving the greatest benefit from multidisciplinary microbial investigations of oceanic ridge flanks

    The use of consumer depth cameras for 3D surface imaging of people with obesity: a feasibility study

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    Objective Three dimensional (3D) surface imaging is a viable alternative to traditional body morphology measures, but the feasibility of using this technique with people with obesity has not been fully established. Therefore, the aim of this study was to investigate the validity, repeatability and acceptability of a consumer depth camera 3D surface imaging system in imaging people with obesity. Methods The concurrent validity of the depth camera based system was investigated by comparing measures of mid-trunk volume to a gold-standard. The repeatability and acceptability of the depth camera system was assessed in people with obesity at a clinic. Results There was evidence of a fixed systematic difference between the depth camera system and the gold standard but excellent correlation between volume estimates (r2 = 0.997), with little evidence of proportional bias. The depth camera system was highly repeatable – low typical error (0.192 L), high intraclass correlation coefficient (>0.999) and low technical error of measurement (0.64%). Depth camera based 3D surface imaging was also acceptable to people with obesity. Conclusion It is feasible (valid, repeatable and acceptable) to use a low cost, flexible 3D surface imaging system to monitor the body size and shape of people with obesity in a clinical setting

    Characterization of metalliferous sediment from a low-temperature hydrothermal environment on the Eastern Flank of the East Pacific Rise

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    Metalliferous deposits are described from the eastern flank of the East Pacific Rise (EPR) offshore Costa Rica, close to a basaltic seamount called “Dorado high”. Based on heat-flow data and porewater profiles, the site is an area of active low-temperature hydrothermal discharge. We focus on the mineralogical and chemical analysis from a 124 cm long gravity core (GC50), located on the northwestern slope of the 100 m high Dorado. In this core, the sediments consist of detrital clay minerals as well as authigenic minerals such as zeolites, apatites, and Fe/Mn-rich oxyhydroxides. In contrast, the reference sediments from adjacent areas without hydrothermal activity are olive gray hemipelagic muds composed of volcanic glass particles, clay minerals, siliceous microfossils, and some detrital quartz and feldspar. Bulk sediment chemistry and chemical enrichment factors calculated with respect to the reference sediment indicate that the most important chemical changes occurred at the base of the core from 100 to 124 cm bsf, with strong enrichments in MnO, CaO, P2O5, and Fe2O3. These enrichments are correlated with the occurrence of authigenic Fe-oxyhydroxide (goethite) and Mn oxide (todorokite and vernadite, at 100 cm bsf), and hydrothermal apatite (110–124 cm bsf). In the upper section of the core from 12 to 70 cm, the sediment is composed of abundant smectite and authigenic phillipsite, and only minor chemical changes can be observed with respect to the reference sediments. The ubiquitous presence of phillipsite suggests that the entire sedimentary column of core GC50 was first affected by diagenesis. However, below 70 cm bsf, these phillipsites are partially dissolved and Fe oxides occur from 110 to 124 cm, followed upward by Mn oxides at 100 cm. This transition from Fe to Mn-rich sediments can be interpreted in terms of an upward increasing redox potential. PAAS-normalized REY patterns of GC50 sediments present clearly negative Ce and positive Y anomalies inherited from seawater at the base of core GC50. These anomalies decrease upward, which we interpret together with the transition from Fe to Mn-rich sediments by an upward migrating low-temperature hydrothermal fluid. Thus, after a first stage of diagenesis, the discharge of a low-temperature hydrothermal fluid occurred through the sedimentary column, leading to the precipitation of hydrothermal compounds that are lacking towards the surface

    Detection of (1,3)-β-d-Glucan in Cerebrospinal Fluid in Histoplasma Meningitis

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    The diagnosis of central nervous system (CNS) histoplasmosis is often difficult. Although cerebrospinal fluid (CSF) (1,3)-β-d-glucan (BDG) is available as a biological marker for the diagnosis of fungal meningitis, there are limited data on its use for the diagnosis of Histoplasma meningitis. We evaluated CSF BDG detection, using the Fungitell assay, in patients with CNS histoplasmosis and controls. A total of 47 cases and 153 controls were identified. The control group included 13 patients with a CNS fungal infection other than histoplasmosis. Forty-nine percent of patients with CNS histoplasmosis and 43.8% of controls were immunocompromised. The median CSF BDG level was 85 pg/ml for cases, compared to <31 pg/ml for all controls (P < 0.05) and 82 pg/ml for controls with other causes of fungal meningitis (P = 0.27). The sensitivity for detection of BDG in CSF was 53.2%, whereas the specificity was 86.9% versus all controls and 46% versus other CNS fungal infections. CSF BDG levels of ≥80 pg/ml are neither sensitive nor specific to support a diagnosis of Histoplasma meningitis

    Selection for muscling in swine and its effect on carcass traits

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    Line differences in weight, litter size at different ages, and in age, loin eye area, and backfat thickness of pigs (adjusted to 200 pounds live weight) were not significant. Sex differences in weight and backfat thickness were significant. Dam groups of progeny differed significantly (P\u3c.0l) in-weights at birth and at 14 and 28 days old and in age, loin eye area, and backfat thickness adjusted to 220 pounds live weight. Hams produced by barrows in the select line were significantly (P\u3c.0l) darker and firmer than those from barrows in the control line.; Swine Day, Manhattan, KS, November 14, 197

    Muscling selection in swine and its effect on carcass traits

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    Pigs farrowed in May, 1972, were the first born in the select and control lines. Performances of animals in the two lines were essentially the same. However, ham firmness and color differed significantly (P\u3c0.0l) between lines, with those in the select line firmer and darker than those from the control line.; Swine Day, Manhattan, KS, November, 197
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