102 research outputs found
Herbivore and Pathogen Damage on Grassland and Woodland Plants: A Test of The Herbivore Uncertainty Principle
Researchers can alter the behaviour and ecology of their study organisms by conducting such seemingly benign activities as non‐destructive measurements and observations. In plant communities, researcher visitation and measurement of plants may increase herbivore damage in some plant species while decreasing it in others. Simply measuring plants could change their competitive ability by altering the amount of herbivore damage that they suffer. Currently, however, there is only limited empirical evidence to support this `herbivore uncertainty principle\u27 (HUP). We tested the HUP by quantifying the amount of herbivore and pathogen damage in 13 plant species (\u3e 1400 individuals) at four different visitation intensities at Cedar Creek Natural History Area, Minnesota, USA. Altogether, we found very little evidence to support the HUP at any intensity of visitation. Researcher visitation did not alter overall plant herbivore damage or survival and we did not detect a significant visitation effect in any of the 13 species. Pathogen damage also did not significantly vary among visitation treatments, although there was some evidence that high visitation caused slightly higher pathogen damage. Based on our results, we question whether this phenomenon should be considered a `principle\u27 of plant ecology
Constraining the Unitarity Triangle with B -> V gamma
We discuss the exclusive radiative decays , , and in QCD factorization within the Standard
Model. The analysis is based on the heavy-quark limit of QCD. Our results for
these decays are complete to next-to-leading order in QCD and to leading order
in the heavy-quark limit. Special emphasis is placed on constraining the
CKM-unitarity triangle from these observables. We propose a theoretically clean
method to determine CKM parameters from the ratio of the decay
spectrum to the branching fraction of . The method is based on
the cancellation of soft hadronic form factors in the large energy limit, which
occurs in a suitable region of phase space. The ratio of the
and branching fractions determines the side of the
standard unitarity triangle with reduced hadronic uncertainties. The recent
Babar bound on implies , with the
limiting uncertainty coming only from the SU(3) breaking form factor ratio
. This constraint is already getting competitive with the constraint from
- mixing. Phenomenological implications from
isospin-breaking effects are briefly discussed.Comment: 23 pages, 8 figure
The Science Case for the Planet Formation Imager (PFI)
Among the most fascinating and hotly-debated areas in contemporary
astrophysics are the means by which planetary systems are assembled from the
large rotating disks of gas and dust which attend a stellar birth. Although
important work has already been, and is still being done both in theory and
observation, a full understanding of the physics of planet formation can only
be achieved by opening observational windows able to directly witness the
process in action. The key requirement is then to probe planet-forming systems
at the natural spatial scales over which material is being assembled. By
definition, this is the so-called Hill Sphere which delineates the region of
influence of a gravitating body within its surrounding environment. The Planet
Formation Imager project (PFI) has crystallized around this challenging goal:
to deliver resolved images of Hill-Sphere-sized structures within candidate
planet-hosting disks in the nearest star-forming regions. In this contribution
we outline the primary science case of PFI. For this purpose, we briefly review
our knowledge about the planet-formation process and discuss recent
observational results that have been obtained on the class of transition disks.
Spectro-photometric and multi-wavelength interferometric studies of these
systems revealed the presence of extended gaps and complex density
inhomogeneities that might be triggered by orbiting planets. We present
detailed 3-D radiation-hydrodynamic simulations of disks with single and
multiple embedded planets, from which we compute synthetic images at
near-infrared, mid-infrared, far-infrared, and sub-millimeter wavelengths,
enabling a direct comparison of the signatures that are detectable with PFI and
complementary facilities such as ALMA. From these simulations, we derive some
preliminary specifications that will guide the array design and technology
roadmap of the facility.Comment: SPIE Astronomical Telescopes and Instrumentation conference, June
2014, Paper ID 9146-120, 13 pages, 3 Figure
Highly Sensitive Detection of Naphthalene in Solvent Vapor Using a Functionalized PBG Refractive Index Sensor
We report an optical refractive index sensor system based on a planar Bragg grating which is functionalized by substituted γ-cyclodextrin to determine low concentrations of naphthalene in solvent vapor. The sensor system exhibits a quasi-instantaneous shift of the Bragg wavelength and is therefore capable for online detection. The overall shift of the Bragg wavelength reveals a linear relationship to the analyte concentration with a gradient of 12.5 ± 1.5 pm/ppm. Due to the spectral resolution and repeatability of the interrogation system, this corresponds to acquisition steps of 80 ppb. Taking into account the experimentally detected signal noise a minimum detection limit of 0.48 ± 0.05 ppm is deduced
The science case for the Planet Formation Imager (PFI)
archiveprefix: arXiv primaryclass: astro-ph.IM eid: 914611 adsurl: http://adsabs.harvard.edu/abs/2014SPIE.9146E..11K adsnote: Provided by the SAO/NASA Astrophysics Data SystemAmong the most fascinating and hotly-debated areas in contemporary astrophysics are the means by which planetary systems are assembled from the large rotating disks of gas and dust which attend a stellar birth. Although important work has already been, and is still being done both in theory and observation, a full understanding of the physics of planet formation can only be achieved by opening observational windows able to directly witness the process in action. The key requirement is then to probe planet-forming systems at the natural spatial scales over which material is being assembled. By definition, this is the so-called Hill Sphere which delineates the region of influence of a gravitating body within its surrounding environment. The Planet Formation Imager project (PFI; http://www.planetformationimager.org) has crystallized around this challenging goal: to deliver resolved images of Hill-Sphere-sized structures within candidate planethosting disks in the nearest star-forming regions. In this contribution we outline the primary science case of PFI. For this purpose, we briefly review our knowledge about the planet-formation process and discuss recent observational results that have been obtained on the class of transition disks. Spectro-photometric and multi-wavelength interferometric studies of these systems revealed the presence of extended gaps and complex density inhomogeneities that might be triggered by orbiting planets. We present detailed 3-D radiation-hydrodynamic simulations of disks with single and multiple embedded planets, from which we compute synthetic images at near-infrared, mid-infrared, far-infrared, and sub-millimeter wavelengths, enabling a direct comparison of the signatures that are detectable with PFI and complementary facilities such as ALMA. From these simulations, we derive some preliminary specifications that will guide the array design and technology roadmap of the facility
Laparoscopic Heller Myotomy Versus Endoscopic Balloon Dilatation for the Treatment of Achalasia A Network Meta-Analysis
Objective: Comparison of short-and long-term effects after laparoscopic Heller myotomy (LHM) and endoscopic balloon dilation (EBD) considering the need for retreatment. Background: Previously published studies have indicated that LHM is the most effective treatment for Achalasia. In contrast to that a recent randomized trial found EBD equivalent to LHM 2 years after initial treatment. Methods: A search in Medline, PubMed, and Cochrane Central Register of Controlled Trials was conducted for prospective studies on interventional achalasia therapy with predefined exclusion criteria. Data on success rates after the initial and repeated treatment were extracted. An adjusted network meta-analysis and meta-regression analysis was used, combined with a headto-head comparison, for follow-up at 12, 24, and 60 months. Results: Sixteen studies including results of 590 LHM and EBD patients were identified. Odds ratio (OR) was 2.20 at 12 months (95% confidence interval: 1.18-4.09; P = 0.01); 5.06 at 24 months (2.61-9.80; P < 0.00001) and 29.83 at 60 months (3.96-224.68; P = 0.001). LHM was also significantly superior for all time points when therapy included re-treatments , and 17.90 (2.17-147.98); P ≤ 0.01 for all comparisons) Complication rates were not significantly different. Meta-regression analysis showed that amount of dilations had a significant impact on treatment effects (P = 0.009). Every dilation (up to 3) improved treatment effect by 11.9% (2.8%-21.8%). Conclusions: In this network meta-analysis, LHM demonstrated superior short-and long-term efficacy and should be considered first-line treatment of esophageal achalasia. Keywords: achalasia, economic cost, endoscopy, esophagus, health, idiopathic achalasia, laparoscopic surgery, meta-analysis, motility disorders, network meta-analysis, review, surgery (Ann Surg 2013;258:943-952 A chalasia is a rare esophageal motility disorder caused by degeneration of the myenteric plexus, resulting in esophageal dysmotility and incomplete lower esophageal sphincter relaxation. The disease is likely caused by a virus-induced autoimmune response, but this is still debated. 1 The incidence in the Western world is 1/100 000. 2-4 Treatment can be pharmacological, endoscopic, or surgical. Pharmacological treatment is only marginally effective and is reserved for patients with mild symptoms or who refuse other treatments. 7-9 Several studies and a large meta-analysis have indicated that laparoscopic Heller myotomy (LHM) is the most effective treatment for achalasia. 3,4,10 However, a recent large prospective randomized controlled trial (RCT) comparing EBD and LHM has challenged this view. 11 This study found similar success rates for EBD and LHM 2 years after initial treatment. However, the number of EBD interventions per patient was notably higher than other studies. 3,11 The purpose of this meta-analysis is to determine which treatment is most effective at relieving symptoms and to further clarify the impact of retreatments for patients with achalasia. METHODS This meta-analysis was registered in the international register of systematic reviews (PROSPERO) (CRD42012002071). 12 Search Strategy and Trial Selection A prospective search of Medline, PubMed, and Cochrane Central Register of Controlled Trials was performed to identify relevant publications. The search keyword was "Esophageal Achalasia." Subsequently, the search was limited by the terms "Human," "Clinical Trial," and publication language "English." Publications from 1975 through October 2011 were considered for review To obtain indirect evidence by adjusted network meta-analysis, relative evidence is needed (LHM vs X; EBD vs X). Therefore, success rates were compared with those of either EBTI or open Heller myotomy (OHM). Direct evidence was achieved from head-to-hea
Effects of antiplatelet therapy on stroke risk by brain imaging features of intracerebral haemorrhage and cerebral small vessel diseases: subgroup analyses of the RESTART randomised, open-label trial
Background
Findings from the RESTART trial suggest that starting antiplatelet therapy might reduce the risk of recurrent symptomatic intracerebral haemorrhage compared with avoiding antiplatelet therapy. Brain imaging features of intracerebral haemorrhage and cerebral small vessel diseases (such as cerebral microbleeds) are associated with greater risks of recurrent intracerebral haemorrhage. We did subgroup analyses of the RESTART trial to explore whether these brain imaging features modify the effects of antiplatelet therapy
GW8510 Increases Insulin Expression in Pancreatic Alpha Cells through Activation of p53 Transcriptional Activity
Background: Expression of insulin in terminally differentiated non-beta cell types in the pancreas could be important to treating type-1 diabetes. Previous findings led us to hypothesize involvement of kinase inhibition in induction of insulin expression in pancreatic alpha cells. Methodology/Principal Findings: Alpha (αTC1.6) cells and human islets were treated with GW8510 and other small-molecule inhibitors for up to 5 days. Alpha cells were assessed for gene- and protein-expression levels, cell-cycle status, promoter occupancy status by chromatin immunoprecipitation (ChIP), and p53-dependent transcriptional activity. GW8510, a putative CDK2 inhibitor, up-regulated insulin expression in mouse alpha cells and enhanced insulin secretion in dissociated human islets. Gene-expression profiling and gene-set enrichment analysis of GW8510-treated alpha cells suggested up-regulation of the p53 pathway. Accordingly, the compound increased p53 transcriptional activity and expression levels of p53 transcriptional targets. A predicted p53 response element in the promoter region of the mouse Ins2 gene was verified by chromatin immunoprecipitation (ChIP). Further, inhibition of Jun N-terminal kinase (JNK) and p38 kinase activities suppressed insulin induction by GW8510. Conclusions/Significance: The induction of Ins2 by GW8510 occurred through p53 in a JNK- and p38-dependent manner. These results implicate p53 activity in modulation of Ins2 expression levels in pancreatic alpha cells, and point to a potential approach toward using small molecules to generate insulin in an alternative cell type.Chemistry and Chemical BiologyMolecular and Cellular Biolog
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