92,811 research outputs found
Long duration thermal hard X-ray sources observed in two eruptive flares
We present observations of two eruptive flares on 17 of December 2006 (C1.9) and 19 of May 2007 (B9.7) which had good coverage with both Hinode and RHESSI. In these flares we see a long lived, gradual thermal hard X-ray source of low emission measure and, relative to the loops observed with GOES and XRT, high temperature. The lack of a non-thermal hard X-ray component and impulsive behaviour is inconsistent with electron beam driven chromospheric evaporation
Vegetation indices as indicators of damage by the sunn pest (Hemiptera: Scutelleridae) to field grown wheat
The sunn pest, Eurygaster integriceps Put. (Hemiptera: Scutelleridae), also known as sting or cereal pest, is one of the most economically important pests of wheat in the world. In this study, a collapsiblenylon cloth cage experiments were conducted to determine the feasibility of using remote sensing techniques to detect stress in wheat caused by the density of sunn pests. The results show we candetect the amount of stress in wheat caused by different life stages of sunn pest with a hand-held radiometer. Normalized difference vegetation index (NDVI) based indices; NDVIsg, NDVId, NDVIr, andstructure insensitive pigment index (SIPI) were chosen out of 19 indices initially tested. The NDVI based vegetation indices derived from hyperspectral data, recorded by a hand held spectroradiometer, were used to determine the predicted indices using the initial number of Sunn Pest (NOSP). Overall, r2 values of all predicted indices calculated for 3rd instars were lower than those of 4th and adult stage. When r2was considered separately, predicted NDVIr index value (87.4) was the highest and predicted SIPI index value is lowest (80.7) in 3rd instars. The highest r2 value was obtained in adult stage of sunn pest isNDVIsg (96.9) compare with NDVId (95.5), NDVIr (92.4) and SIPI (94.2). It was also concluded that remote sensing could detect not only the different stages pest damage on wheat, but also the number of sunnpest stages density affect in controlled experiments
Distances from Surface Brightness Fluctuations
The practice of measuring galaxy distances from their spatial fluctuations in
surface brightness is now a decade old. While several past articles have
included some review material, this is the first intended as a comprehensive
review of the surface brightness fluctuation (SBF) method. The method is
conceptually quite simple, the basic idea being that nearby (but unresolved)
star clusters and galaxies appear "bumpy", while more distant ones appear
smooth. This is quantified via a measurement of the amplitude of the Poisson
fluctuations in the number of unresolved stars encompassed by a CCD pixel
(usually in an image of an elliptical galaxy). Here, we describe the technical
details and difficulties involved in making SBF measurements, discuss
theoretical and empirical calibrations of the method, and review the numerous
applications of the method from the ground and space, in the optical and
near-infrared. We include discussions of stellar population effects and the
"universality" of the SBF standard candle. A final section considers the future
of the method.Comment: Invited review article to appear in: `Post-Hipparcos Cosmic Candles',
A. Heck & F. Caputo (Eds), Kluwer Academic Publ., Dordrecht, in press. 22
pages, including 3 postscript figures; uses Kluwer's crckapb.sty LaTex macro
file, enclose
Relating near-Earth observations of an interplanetary coronal mass ejection to the conditions at its site of origin in the solar corona
A halo coronal mass ejection (CME) was detected on January 20, 2004. We use solar remote sensing data (SOHO, Culgoora) and near-Earth in situ data (Cluster) to identify the CME source event and show that it was a long duration flare in which a magnetic flux rope was ejected, carrying overlying coronal arcade material along with it. We demonstrate that signatures of both the arcade material and the flux rope material are clearly identifiable in the Cluster and ACE data, indicating that the magnetic field orientations changed little as the material traveled to the Earth, and that the methods we used to infer coronal magnetic field configurations are effective
A Upf3b-mutant mouse model with behavioral and neurogenesis defects.
Nonsense-mediated RNA decay (NMD) is a highly conserved and selective RNA degradation pathway that acts on RNAs terminating their reading frames in specific contexts. NMD is regulated in a tissue-specific and developmentally controlled manner, raising the possibility that it influences developmental events. Indeed, loss or depletion of NMD factors have been shown to disrupt developmental events in organisms spanning the phylogenetic scale. In humans, mutations in the NMD factor gene, UPF3B, cause intellectual disability (ID) and are strongly associated with autism spectrum disorder (ASD), attention deficit hyperactivity disorder (ADHD) and schizophrenia (SCZ). Here, we report the generation and characterization of mice harboring a null Upf3b allele. These Upf3b-null mice exhibit deficits in fear-conditioned learning, but not spatial learning. Upf3b-null mice also have a profound defect in prepulse inhibition (PPI), a measure of sensorimotor gating commonly deficient in individuals with SCZ and other brain disorders. Consistent with both their PPI and learning defects, cortical pyramidal neurons from Upf3b-null mice display deficient dendritic spine maturation in vivo. In addition, neural stem cells from Upf3b-null mice have impaired ability to undergo differentiation and require prolonged culture to give rise to functional neurons with electrical activity. RNA sequencing (RNAseq) analysis of the frontal cortex identified UPF3B-regulated RNAs, including direct NMD target transcripts encoding proteins with known functions in neural differentiation, maturation and disease. We suggest Upf3b-null mice serve as a novel model system to decipher cellular and molecular defects underlying ID and neurodevelopmental disorders
No alignment of cattle along geomagnetic field lines found
This paper presents a study of the body orientation of domestic cattle on
free pastures in several European states, based on Google satellite
photographs. In sum, 232 herds with 3412 individuals were evaluated. Two
independent groups participated in our study and came to the same conclusion
that, in contradiction to the recent findings of other researchers, no
alignment of the animals and of their herds along geomagnetic field lines could
be found. Several possible reasons for this discrepancy should be taken into
account: poor quality of Google satellite photographs, difficulties in
determining the body axis, selection of herds or animals within herds, lack of
blinding in the evaluation, possible subconscious bias, and, most importantly,
high sensitivity of the calculated main directions of the Rayleigh vectors to
some kind of bias or to some overlooked or ignored confounder. This factor
could easily have led to an unsubstantiated positive conclusion about the
existence of magnetoreception.Comment: Added electronic supplement with source dat
Fine-tuning implications for complementary dark matter and LHC SUSY searches
The requirement that SUSY should solve the hierarchy problem without undue
fine-tuning imposes severe constraints on the new supersymmetric states. With
the MSSM spectrum and soft SUSY breaking originating from universal scalar and
gaugino masses at the Grand Unification scale, we show that the low-fine-tuned
regions fall into two classes that will require complementary collider and dark
matter searches to explore in the near future. The first class has relatively
light gluinos or squarks which should be found by the LHC in its first run. We
identify the multijet plus E_T^miss signal as the optimal channel and determine
the discovery potential in the first run. The second class has heavier gluinos
and squarks but the LSP has a significant Higgsino component and should be seen
by the next generation of direct dark matter detection experiments. The
combined information from the 7 TeV LHC run and the next generation of direct
detection experiments can test almost all of the CMSSM parameter space
consistent with dark matter and EW constraints, corresponding to a fine-tuning
not worse than 1:100. To cover the complete low-fine-tuned region by SUSY
searches at the LHC will require running at the full 14 TeV CM energy; in
addition it may be tested indirectly by Higgs searches covering the mass range
below 120 GeV.Comment: References added. Version accepted for publication in JHE
Efficacy of Prehabilitation Including Exercise on Postoperative Outcomes Following Abdominal Cancer Surgery: A Systematic Review and Meta-Analysis
OBJECTIVE: This systematic review set out to identify, evaluate and synthesise the evidence examining the effect of prehabilitation including exercise on postoperative outcomes following abdominal cancer surgery. METHODS: Five electronic databases (MEDLINE 1946-2020, EMBASE 1947-2020, CINAHL 1937-2020, PEDro 1999-2020, and Cochrane Central Registry of Controlled Trials 1991-2020) were systematically searched (until August 2020) for randomised controlled trials (RCTs) that investigated the effects of prehabilitation interventions in patients undergoing abdominal cancer surgery. This review included any form of prehabilitation either unimodal or multimodal that included whole body and/or respiratory exercises as a stand-alone intervention or in addition to other prehabilitation interventions (such as nutrition and psychology) compared to standard care. RESULTS: Twenty-two studies were included in the systematic review and 21 studies in the meta-analysis. There was moderate quality of evidence that multimodal prehabilitation improves pre-operative functional capacity as measured by 6 min walk distance (Mean difference [MD] 33.09 metres, 95% CI 17.69–48.50; p = <0.01) but improvement in cardiorespiratory fitness such as preoperative oxygen consumption at peak exercise (VO2 peak; MD 1.74 mL/kg/min, 95% CI −0.03–3.50; p = 0.05) and anaerobic threshold (AT; MD 1.21 mL/kg/min, 95% CI −0.34–2.76; p = 0.13) were not significant. A reduction in hospital length of stay (MD 3.68 days, 95% CI 0.92–6.44; p = 0.009) was observed but no effect was observed for postoperative complications (Odds Ratio [OR] 0.81, 95% CI 0.55–1.18; p = 0.27), pulmonary complications (OR 0.53, 95% CI 0.28–1.01; p = 0.05), hospital re-admission (OR 1.07, 95% CI 0.61–1.90; p = 0.81) or postoperative mortality (OR 0.95, 95% CI 0.43–2.09, p = 0.90). CONCLUSION: Multimodal prehabilitation improves preoperative functional capacity with reduction in hospital length of stay. This supports the need for ongoing research on innovative cost-effective prehabilitation approaches, research within large multicentre studies to verify this effect and to explore implementation strategies within clinical practise
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