4,071 research outputs found
Multi-epoch infrared photometry of the star forming region G173.58+2.45
We present a multi-epoch infrared photometric study of the intermediate-mass
star forming region G173.58+2.45. Photometric observations are obtained using
the near-infrared filters and narrow-band filters centered at the
wavelengths of H (1-0) S(1) (2.122 m) and [FeII] (1.644 m) lines.
The H image shows molecular emission from shocked gas, implying the
presence of multiple star formation and associated outflow activity. We see
evidence for several collimated outflows. The most extended jet is at least
0.25 pc in length and has a collimation factor of 10, which may be
associated with a binary system within the central cluster, resolved for the
first time here. This outflow is found to be episodic; probably occurring or
getting enhanced during the periastron passage of the binary. We also find that
the variable star in the vicinity of the outflow source, which was known as a
FU Ori type star, is probably not a FU Ori object. However, it does drive a
spectacular outflow and the variability is likely to be related to accretion,
when large clouds of gas and dust spiral in towards the central source. Many
other convincing accretion-outflow systems and YSO candidates are discovered in
the field.Comment: 15 pages, 9 figures, accepted for publication in MNRA
Rhythms of Locomotion Expressed by Limulus polyphemus, the American Horseshoe Crab: I. Synchronization by Artificial Tides
Limulus polyphemus, the American horseshoe crab, has an endogenous clock that drives circatidal rhythms of locomotor activity. In this study, we examined the ability of artificial tides to entrain the locomotor rhythms of Limulus in the laboratory. In experiments one and two, the activity of 16 individuals of L. polyphemus was monitored with activity boxes and “running wheels.” When the crabs were exposed to artificial tides created by changes in water depth, circatidal rhythms were observed in animals exposed to 12.4-h “tidal” cycles of either water depth changes (8 of 8 animals) or inundation (7 of 8 animals). In experiment three, an additional 8 animals were exposed to water depth changes under cyclic conditions of light and dark and then monitored for 10 days with no imposed artificial tides. Most animals (5) clearly synchronized their activity to the imposed artificial tidal cycles, and 3 of these animals showed clear evidence of entrainment after the artificial tides were terminated. Overall, these results demonstrate that the endogenous tidal clock that influences locomotion in Limulus can be entrained by imposed artificial tides. In the laboratory, these tidal cues override the influence of light/dark cycles. In their natural habitat, where both tidal and photoperiod inputs are typically always present, their activity rhythms are likely to be much more complex
A ground-based NUV secondary eclipse observation of KELT-9b
KELT-9b is a recently discovered exoplanet with a 1.49 d orbit around a
B9.5/A0-type star. The unparalleled levels of UV irradiation it receives from
its host star put KELT-9b in its own unique class of ultra-hot Jupiters, with
an equilibrium temperature > 4000 K. The high quantities of dissociated
hydrogen and atomic metals present in the dayside atmosphere of KELT-9b bear
more resemblance to a K-type star than a gas giant. We present a single
observation of KELT-9b during its secondary eclipse, taken with the Wide Field
Camera on the Isaac Newton Telescope (INT). This observation was taken in the
U-band, a window particularly sensitive to Rayleigh scattering. We do not
detect a secondary eclipse signal, but our 3 upper limit of 181 ppm on
the depth allows us to constrain the dayside temperature of KELT-9b at
pressures of ~30 mbar to 4995 K (3). Although we can place an
observational constraint of 0.14, our models suggest that the actual
value is considerably lower than this due to H opacity. This places KELT-9b
squarely in the albedo regime populated by its cooler cousins, almost all of
which reflect very small components of the light incident on their daysides.
This work demonstrates the ability of ground-based 2m-class telescopes like the
INT to perform secondary eclipse studies in the NUV, which have previously only
been conducted from space-based facilities.Comment: Accepted in ApJL. 7 pages, 3 figure
Evaluation of the Water Footprint of Beef Cattle Production in Nebraska
Data were compiled on feed usage to model the amount of water needed to produce beef in typical Nebraska production systems. Production systems where cows were wintered on corn residue utilized 18% less water than systems utilizing native range as a wintering source, because of water allocations. Therefore, the water footprint (gallons of water required to produce one pound of boneless meat) was decreased by 18%. In addition, increasing the dietary inclusion of distillers grains from 0% to 40% decreased the water footprint in the finishing phase by 29%, again based on water allocation. Utilizing corn residue and distillers grains in Nebraska beef cattle systems decreases the overall water footprint of production. Additionally, the water footprint of the systems analyzed was 80% green water as rain, minimizing the environmental impact of beef production on freshwater use and ecological water balance
Embryo collection induces transient activation of XBP1 arm of the ER stress response while embryo vitrification does not.
Embryo cryopreservation has become a standard procedure in the practice of assisted reproduction. While routinely performed in IVF labs, the effects of embryo vitrification on the molecular mechanisms governing preimplantation development remain largely unknown. The endoplasmic reticulum stress (ER stress) response is an evolutionary conserved mechanism that cells employ to manage ER stress. ER stress can be defined as an imbalance between protein synthesis and secretion within the ER. The primary focus of this study was to investigate whether standard embryo manipulations, including embryo collection, culture and vitrification, result in activation of the ER stress pathway in vitro and to determine whether the embryo utilizes the unfolded protein response as an adaptive response. Our results indicate that the major ER stress pathway constituents are present at all stages of preimplantation development and that the activation of ER stress pathways can be induced at the 8-cell, morula and blastocyst stages. Additionally, we have demonstrated that the IRE1α arm of the ER Stress pathway is activated in freshly collected embryos but contrastingly, this ER Stress arm is not activated following embryo vitrification. It is important to understand the possible stresses that Assisted Reproductive Technologies place on the embryo and the mechanisms the embryo employs to adapt to these stresses. This study indicates that among the adaptive pathways available, cultured mammalian embryos can employ the ER stress pathway. Assisted reproduction techniques should be aware that their activities may induce the ER stress pathway in their patients\u27 early embryos
Multi-Scale Phenology of Temperate Grasslands: Improving Monitoring and Management With Near-Surface Phenocams
Grasslands of the Australian Southern Tablelands represent a patchwork of native and exotic systems, occupying a continuum of C3-dominated to C4-dominated grasslands where composition depends on disturbance factors (e.g., grazing) and climate. Managing these complex landscapes is both challenging and critical for maintaining the security of Australia's pasture industries, and for protecting the biodiversity of native remnants. Differentiating C3 from C4 vegetation has been a prominent theme in remote sensing research due to distinct C3/C4 seasonal productivity patterns (phenology) and high uncertainty about how C3/C4 vegetation will respond to a changing climate. Phenology is used in northern hemisphere ecosystems for a range of purposes but has not been widely adopted in Australia, where dynamic climate often results in non-repetitive seasonal vegetation patterns. We employed time-lapse cameras (phenocams) to study the phenology of twelve grassland areas dominated by cool season (C3) and warm season (C4), native or exotic grasses near Canberra, Australia. Our aims were to assess phenological characteristics of the functional types and to determine the drivers of phenological variability. We compared the fine-scale phenocam seasonal profiles with field sampling and MODIS/Landsat satellite products to assess paddock-to-landscape functioning. We found C3/C4 species dominance to be the primary driver of phenological differences among grassland types, with C3 grasslands demonstrating peak greenness in spring, and senescing rapidly in response to high summer temperatures. In contrast, C4 grasslands showed peak activity in Austral summer and autumn (January-March). Some sites displayed primary and secondary peaks dependent on rainfall and species composition. We found that the proportion of dead vegetation is an important biophysical driver of grassland phenology, as were grazing pressures and species-dependent responses to rainfall and temperature. The satellite and field datasets were in general agreement with the phenocam results. However, the higher temporal fidelity of the cameras captured changes in vegetation not observed in the coarser satellite or field results. Our phenocam data shows consistent periods of increasing and decreasing greenness over as little as 5 days. Applications for management of grasslands in temperate Australia include the identification of remnant native grasslands, tracking biosecurity issues, and assessing productivity responses to climate variability
Extreme asteroids in the Pan-STARRS 1 Survey
Using the first 18 months of the Pan-STARRS 1 survey we have identified 33
candidate high-amplitude objects for follow-up observations and carried out
observations of 22 asteroids. 4 of the observed objects were found to have
observed amplitude mag. We find that these high amplitude
objects are most simply explained by single rubble pile objects with some
density-dependent internal strength, allowing them to resist mass shedding even
at their highly elongated shapes. 3 further objects although below the cut-off
for 'high-amplitude' had a combination of elongation and rotation period which
also may require internal cohesive strength, depending on the density of the
body. We find that none of the 'high-amplitude asteroids' identified here
require any unusual cohesive strengths to resist rotational fission. 3
asteroids were sufficiently observed to allow for shape and spin pole models to
be determined through light curve inversion. 45864 was determined to have
retrograde rotation with spin pole axes and asteroid 206167 was found to have best fit spin
pole axes , . An additional
object not initially measured with mag, 49257, was determined to
have a shape model which does suggest a high-amplitude object. Its spin pole
axes were best fit for values .
In the course of this project to date no large super-fast rotators ( h) have been identified.Comment: 31 pages; accepted by A
Differential Increase in Taurine Levels by Low-Dose Ethanol in the Dorsal and Ventral Striatum Revealed by Microdialysis With On-Line Capillary Electrophoresis
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/66164/1/01.ALC.0000131979.78003.34.pd
Inequity in access to transplantation in the UK
Background and objectives Despite the presence of a universal health care system, it is unclear if there is intercenter variation in access to kidney transplantation in the United Kingdom. This study aims to assess whether equity exists in access to kidney transplantation in the United Kingdom after adjustment for patient-specific factors and center practice patterns.
Design, setting, participants, & measurements In this prospective, observational cohort study including all 71 United Kingdom kidney centers, incident RRT patients recruited between November 2011 and March 2013 as part of the Access to Transplantation and Transplant Outcome Measures study were analyzed to assess preemptive listing (n=2676) and listing within 2 years of starting dialysis (n=1970) by center.
Results Seven hundred and six participants (26%) were listed preemptively, whereas 585 (30%) were listed within 2 years of commencing dialysis. The interquartile range across centers was 6%–33% for preemptive listing and 25%–40% for listing after starting dialysis. Patient factors, including increasing age, most comorbidities, body mass index >35 kg/m2, and lower socioeconomic status, were associated with a lower likelihood of being listed and accounted for 89% and 97% of measured intercenter variation for preemptive listing and listing within 2 years of starting dialysis, respectively. Asian (odds ratio, 0.49; 95% confidence interval, 0.33 to 0.72) and Black (odds ratio, 0.43; 95% confidence interval, 0.26 to 0.71) participants were both associated with reduced access to preemptive listing; however Asian participants were associated with a higher likelihood of being listed after starting dialysis (odds ratio, 1.42; 95% confidence interval, 1.12 to 1.79). As for center factors, being registered at a transplanting center (odds ratio, 3.1; 95% confidence interval, 2.36 to 4.07) and a universal approach to discussing transplantation (odds ratio, 1.4; 95% confidence interval, 1.08 to 1.78) were associated with higher preemptive listing, whereas using a written protocol was associated negatively with listing within 2 years of starting dialysis (odds ratio, 0.7; 95% confidence interval, 0.58 to 0.9).
Conclusions Patient case mix accounts for most of the intercenter variation seen in access to transplantation in the United Kingdom, with practice patterns also contributing some variation. Socioeconomic inequity exists despite having a universal health care system
Cross-linking of structural proteins in ageing skin: An in situ assay for the detection of amine oxidase activity
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