194 research outputs found
PoGOLite - A High Sensitivity Balloon-Borne Soft Gamma-ray Polarimeter
We describe a new balloon-borne instrument (PoGOLite) capable of detecting
10% polarisation from 200mCrab point-like sources between 25 and 80keV in one 6
hour flight. Polarisation measurements in the soft gamma-ray band are expected
to provide a powerful probe into high-energy emission mechanisms as well as the
distribution of magnetic fields, radiation fields and interstellar matter. At
present, only exploratory polarisation measurements have been carried out in
the soft gamma-ray band. Reduction of the large background produced by
cosmic-ray particles has been the biggest challenge. PoGOLite uses Compton
scattering and photo-absorption in an array of 217 well-type phoswich detector
cells made of plastic and BGO scintillators surrounded by a BGO anticoincidence
shield and a thick polyethylene neutron shield. The narrow FOV (1.25msr)
obtained with well-type phoswich detector technology and the use of thick
background shields enhance the detected S/N ratio. Event selections based on
recorded phototube waveforms and Compton kinematics reduce the background to
that expected for a 40-100mCrab source between 25 and 50keV. A 6 hour
observation on the Crab will differentiate between the Polar Cap/Slot Gap,
Outer Gap, and Caustic models with greater than 5 sigma; and also cleanly
identify the Compton reflection component in the Cygnus X-1 hard state. The
first flight is planned for 2010 and long-duration flights from Sweden to
Northern Canada are foreseen thereafter.Comment: 11 pages, 11 figures, 2 table
Lorentz breaking Effective Field Theory and observational tests
Analogue models of gravity have provided an experimentally realizable test
field for our ideas on quantum field theory in curved spacetimes but they have
also inspired the investigation of possible departures from exact Lorentz
invariance at microscopic scales. In this role they have joined, and sometime
anticipated, several quantum gravity models characterized by Lorentz breaking
phenomenology. A crucial difference between these speculations and other ones
associated to quantum gravity scenarios, is the possibility to carry out
observational and experimental tests which have nowadays led to a broad range
of constraints on departures from Lorentz invariance. We shall review here the
effective field theory approach to Lorentz breaking in the matter sector,
present the constraints provided by the available observations and finally
discuss the implications of the persisting uncertainty on the composition of
the ultra high energy cosmic rays for the constraints on the higher order,
analogue gravity inspired, Lorentz violations.Comment: 47 pages, 4 figures. Lecture Notes for the IX SIGRAV School on
"Analogue Gravity", Como (Italy), May 2011. V.3. Typo corrected, references
adde
Open Questions in GRB Physics
Open questions in GRB physics are summarized as of 2011, including
classification, progenitor, central engine, ejecta composition, energy
dissipation and particle acceleration mechanism, radiation mechanism, long term
engine activity, external shock afterglow physics, origin of high energy
emission, and cosmological setting. Prospects of addressing some of these
problems with the upcoming Chinese-French GRB mission, SVOM, are outlined.Comment: 27 pages. To appear in a special issue of Comptes Rendus Physique
"GRB studies in the SVOM era", Eds. F. Daigne, G. Dubu
Robotic, laparoscopic and open surgery for gastric cancer compared on surgical, clinical and oncological outcomes: a multi-institutional chart review. A study protocol of the International study group on Minimally Invasive surgery for GASTRIc Cancer: IMIGASTRIC
Micro-management: curbing chronic wound infection
Chronic wounds, including pressure ulcers, foot ulcers and venous leg ulcers have a detrimental impact on the health and well-being of an estimated 2% of people in the UK. Chronic wounds are normally colonised by bacteria and in some instances bacterial load increases sufficiently for infection to ensue. Once a chronic wound becomes infected it is difficult to resolve and a combination of continuous inflammation and bacterial proliferation makes these wounds difficult to manage. A state of prolonged inflammation can occur as a result of impaired homeostatic pathways which are exacerbated by bacterial growth. Chronic, infected wounds can persist for many months or even years, sometimes requiring surgical intervention in the form of regular debridement or amputation when other strategies such as antimicrobial treatments fail. The complex relationships between both oral microbiota and the host have been extensively characterised, including the shift from health to disease, and has allowed for the development of numerous control strategies. This knowledge combined with contemporary studies of chronic infected wounds can be used to develop an understanding of the relationship between the host and microorganism in the chronic wound environment. Such information has the potential to inform wound management including strategies to control infection and promote wound healing
Are Happiness and Life Satisfaction Different Across Religious groups? Exploring Determinants of Happiness and Life Satisfaction
This study explores whether different religions experience different levels of happiness and life satisfaction and in case this is affected by country economic and cultural environment. Using World Value Survey (from 1981 to 2014), this study found that individual religiosity and country level of development play a significant role in shaping people’s subjective well-being (SWB). Protestants, Buddhists and Roman Catholic were happier and most satisfied with their lives compared to other religious groups. Orthodox has the lowest SWB. Health status, household’s financial satisfaction and freedom of choice are means by which religious groups and governments across the globe can improve the SWB of their citizens. Keywords: happiness; life satisfaction; religion; religious differences; cultur
FluTE, a Publicly Available Stochastic Influenza Epidemic Simulation Model
Mathematical and computer models of epidemics have contributed to our understanding of the spread of infectious disease and the measures needed to contain or mitigate them. To help prepare for future influenza seasonal epidemics or pandemics, we developed a new stochastic model of the spread of influenza across a large population. Individuals in this model have realistic social contact networks, and transmission and infections are based on the current state of knowledge of the natural history of influenza. The model has been calibrated so that outcomes are consistent with the 1957/1958 Asian A(H2N2) and 2009 pandemic A(H1N1) influenza viruses. We present examples of how this model can be used to study the dynamics of influenza epidemics in the United States and simulate how to mitigate or delay them using pharmaceutical interventions and social distancing measures. Computer simulation models play an essential role in informing public policy and evaluating pandemic preparedness plans. We have made the source code of this model publicly available to encourage its use and further development
The role of adjuvant chemotherapy for patients with stage II and stage III gastric adenocarcinoma after surgery plus D2 lymph node dissection: a real-world observation
EphA2-receptor deficiency exacerbates myocardial infarction and reduces survival in hyperglycemic mice
Background
We have previously shown that EphrinA1/EphA expression profile changes in response to myocardial infarction (MI), exogenous EphrinA1-Fc administration following MI positively influences wound healing, and that deletion of the EphA2 Receptor (EphA2-R) exacerbates injury and remodeling. To determine whether or not ephrinA1-Fc would be of therapeutic value in the hyperglycemic infarcted heart, it is critical to evaluate how ephrinA1/EphA signaling changes in the hyperglycemic myocardium in response to MI.
Methods
Streptozotocin (STZ)-induced hyperglycemia in wild type (WT) and EphA2-receptor mutant (EphA2-R-M) mice was initiated by an intraperitoneal injection of STZ (150 mg/kg) 10 days before surgery. MI was induced by permanent ligation of the left anterior descending coronary artery and analyses were performed at 4 days post-MI. ANOVAs with Student-Newman Keuls multiple comparison post-hoc analysis illustrated which groups were significantly different, with significance of at least p < 0.05.
Results
Both WT and EphA2-R-M mice responded adversely to STZ, but only hyperglycemic EphA2-R-M mice had lower ejection fraction (EF) and fractional shortening (FS). At 4 days post-MI, we observed greater post-MI mortality in EphA2-R-M mice compared with WT and this was greater still in the EphA2-R-M hyperglycemic mice. Although infarct size was greater in hyperglycemic WT mice vs normoglycemic mice, there was no difference between hyperglycemic EphA2-R-M mice and normoglycemic EphA2-R-M mice. The hypertrophic response that normally occurs in viable myocardium remote to the infarct was noticeably absent in epicardial cardiomyocytes and cardiac dysfunction worsened in hyperglycemic EphA2-R-M hearts post-MI. The characteristic interstitial fibrotic response in the compensating myocardium remote to the infarct also did not occur in hyperglycemic EphA2-R-M mouse hearts to the same extent as that observed in the hyperglycemic WT mouse hearts. Differences in neutrophil and pan-leukocyte infiltration and serum cytokines implicate EphA2-R in modulation of injury and the differences in ephrinA1 and EphA6-R expression in governing this are discussed.
Conclusions
We conclude that EphA2-mutant mice are more prone to hyperglycemia-induced increased injury, decreased survival, and worsened LV remodeling due to impaired wound healing
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