172 research outputs found
TEV GAMMA-RAYS FROM PROTON BLAZARS
Proton acceleration in nearby blazars can be diagnosed measuring their
intense TeV -ray emission. Flux predictions for 1101+384 (Mrk421) and
1219+285 (ON231), both strong EGRET sources (0.1-10 GeV), are obtained from
model spectra of unsaturated synchrotron pair cascades fitted to publicly
available multifrequency data. An experimental effort to confirm the predicted
emission in the range 1-10 TeV would be of great importance for the problems of
the origin of cosmic rays, the era of galaxy formation and the cosmological
distance scale.Comment: 10 pages of latex using Kluwer spacekap.sty, to appear in Space
Science Review
Automated peritoneal lavage: An extremely rapid and safe way to induce hypothermia in post-resuscitation patients
Introduction: Mild therapeutic hypothermia (MTH) is a worldwide used therapy to improve neurological outcome in patients successfully resuscitated after cardiac arrest (CA). Preclinical data suggest that timing and speed of induction are related to reduction of secondary brain damage and improved outcome.Methods: Aiming at a rapid induction and stable maintenance phase, MTH induced via continuous peritoneal lavage (PL) using the Velomedix® Inc. automated PL system was evaluated and compared to historical controls in which hypothermia was achieved using cooled saline intravenous infusions and cooled blankets. Results: In 16 PL patients, time to reach the core target temperature of 32.5°C was 30 minutes (interquartile range (IQR): 19 to 60), which was significantly faster compare to 150 minutes (IQR: 112 to 240) in controls. The median rate of cooling during the induction phase in the PL group of 4.1°C/h (IQR: 2.2 to 8.2) was significantly faster compared to 0.9°C/h (IQR: 0.5 to 1.3) in controls. During the 24-hour maintenance phase mean core temperature in the PL patients was 32.38 ± 0.18°C (range: 32.03 to 32.69°C) and in control patients 32.46 ± 0.48°C (range: 31.20 to 33.63°C), indicating more steady temperature control in the PL group compared to controls. Furthermore, the coefficient of variation (VC) for temperature during the maintenance phase was lower in the PL group (VC: 0.5%) compared to the control group (VC: 1.5%). In contrast to 23% of the control patients, none of the PL patients showed an overshoot of hypothermia below 31°C during the maintenance phase. Survival and neurological outcome was not different between the two groups. Neither shivering nor complications related to insertion or use of the PL method were observed.Conclusions: Using PL in post-CA patients results in a rapidly reached target temperature and a very precise maintenance, unprecedented in clinical studies evaluating MTH techniques. This opens the way to investigate the effects on neurological outcome and survival of ultra-rapid cooling compared to standard cooling in controlled trials in various patient groups.Trial Registration: ClinicalTrials.gov: NCT01016236. © 2013 de Waard et al.; licensee BioMed Central Ltd
High Energy Neutrinos from Quasars
We review and clarify the assumptions of our basic model for neutrino
production in the cores of quasars, as well as those modifications to the model
subsequently made by other workers. We also present a revised estimate of the
neutrino background flux and spectrum obtained using more recent empirical
studies of quasars and their evolution. We compare our results with other
thoeretical calculations and experimental upper limits on the AGN neutrino
background flux. We also estimate possible neutrino fluxes from the jets of
blazars detected recently by the EGRET experiment on the Compton Gamma Ray
Observatory. We discuss the theoretical implications of these estimates.Comment: 14 pg., ps file (includes figures), To be published in Space Science
Review
Cosmic ray diffusion near the Bohm limit in the Cassiopeia A supernova remnant
Supernova remnants (SNRs) are believed to be the primary location of the
acceleration of Galactic cosmic rays, via diffusive shock (Fermi) acceleration.
Despite considerable theoretical work the precise details are still unknown, in
part because of the difficulty in directly observing nucleons that are
accelerated to TeV energies in, and affect the structure of, the SNR shocks.
However, for the last ten years, X-ray observatories ASCA, and more recently
Chandra, XMM-Newton, and Suzaku have made it possible to image the synchrotron
emission at keV energies produced by cosmic-ray electrons accelerated in the
SNR shocks. In this article, we describe a spatially-resolved spectroscopic
analysis of Chandra observations of the Galactic SNR Cassiopeia A to map the
cutoff frequencies of electrons accelerated in the forward shock. We set upper
limits on the electron diffusion coefficient and find locations where particles
appear to be accelerated nearly as fast as theoretically possible (the Bohm
limit).Comment: 18 pages, 5 figures. Accepted for publication in Nature Physics (DOI
below), final version available week of August 28, 2006 at
http://www.nature.com/nphy
Legitimacy in REDD+ governance in Indonesia
This paper addresses the question of legitimacy in REDD+ governance in Indonesia. It develops a legitimacy framework that builds on elements of Scharpf (J Eur Pub Policy 4(1):18–36, 1997) input and output legitimacy concept and the political economy lens described by Brockhaus and Angelsen (Analysing REDD+: Challenges and choices, CIFOR, Bogor, 2012). Using data collected through key informant interviews and focus groups, we identify and explore stakeholder perceptions of legitimacy. The analysis reveals a complex interplay between input and output legitimacy, finding that state, non-state and hybrid actors perceive output legitimacy (i.e. project outcomes) as highly dependent on the level of input legitimacy achieved during the governance process. Non-state actors perceive proxies for input legitimacy, such as participation and inclusion of local people, as goals in themselves. In the main, they perceive inclusion to be integral to the empowerment of local people. They perceive output legitimacy as less important because of the intangibility of REDD+ outcomes at this stage in the process. The findings also highlight the challenges associated with measuring the legitimacy of REDD+ governance in Indonesia
Clinical outcomes resulting from telemedicine interventions: a systematic review
BACKGROUND: The use of telemedicine is growing, but its efficacy for achieving comparable or improved clinical outcomes has not been established in many medical specialties. The objective of this systematic review was to evaluate the efficacy of telemedicine interventions for health outcomes in two classes of application: home-based and office/hospital-based. METHODS: Data sources for the study included deports of studies from the MEDLINE, EMBASE, CINAHL, and HealthSTAR databases; searching of bibliographies of review and other articles; and consultation of printed resources as well as investigators in the field. We included studies that were relevant to at least one of the two classes of telemedicine and addressed the assessment of efficacy for clinical outcomes with data of reported results. We excluded studies where the service did not historically require face-to-face encounters (e.g., radiology or pathology diagnosis). All included articles were abstracted and graded for quality and direction of the evidence. RESULTS: A total of 25 articles met inclusion criteria and were assessed. The strongest evidence for the efficacy of telemedicine in clinical outcomes comes from home-based telemedicine in the areas of chronic disease management, hypertension, and AIDS. The value of home glucose monitoring in diabetes mellitus is conflicting. There is also reasonable evidence that telemedicine is comparable to face-to-face care in emergency medicine and is beneficial in surgical and neonatal intensive care units as well as patient transfer in neurosurgery. CONCLUSIONS: Despite the widespread use of telemedicine in virtually all major areas of health care, evidence concerning the benefits of its use exists in only a small number of them. Further randomized controlled trials must be done to determine where its use is most effective
Bridging reproductive and microbial ecology: a case study in arbuscular mycorrhizal fungi
Offspring size is a key trait for understanding the reproductive ecology of species, yet studies addressing the ecological meaning of offspring size have so far been limited to macro-organisms. We consider this a missed opportunity in microbial ecology and provide what we believe is the first formal study of offspring-size variation in microbes using reproductive models developed for macro-organisms. We mapped the entire distribution of fungal spore size in the arbuscular mycorrhizal (AM) fungi (subphylum Glomeromycotina) and tested allometric expectations of this trait to offspring (spore) output and body size. Our results reveal a potential paradox in the reproductive ecology of AM fungi: while large spore-size variation is maintained through evolutionary time (independent of body size), increases in spore size trade off with spore output. That is, parental mycelia of large-spored species produce fewer spores and thus may have a fitness disadvantage compared to small-spored species. The persistence of the large-spore strategy, despite this apparent fitness disadvantage, suggests the existence of advantages to large-spored species that could manifest later in fungal life history. Thus, we consider that solving this paradox opens the door to fruitful future research establishing the relationship between offspring size and other AM life history traits
Surface and Adhesion Characteristics of Current and Next Generation Steel Packaging Materials
Steel packaging remains an important mean by which foodstuffs and other products can be stored safely for a prolonged period of time. The industry is being challenged by the dual legislative pressures which require the elimination of Chrome (VI) from the manufacturing process and the elimination of bisphenol A as a component from the lacquer system. Initial indications suggest lower adhesive performance, and it has been postulated that thermal treatment may be a mean of improv- ing adhesion. Three substrates (two current and one future) were physically and chemically characterized prior and post treatment and the resultant impact of adhesion was quantified. The net impact of the thermal treatment is that it increases the adhesion of the lacquer on the surface. As there is minimal change in the physical characteristics of the surface, the authors propose that this is a result of changes in the chemical surface species, particularly the increase in the oxidic nature of each of the substrates which provides additional bonding sites for the organic species in the lacquer. These trends are observed for current substrate materials as well as next generation Chrome VI free substrate. Next generation replacement substrate materials perform better than current materials for dry adhesion while next generation bisphenol A non-intent lacquer mate- rials perform poorer than the current epoxy phenolic materials
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