Normalization of aortic function during arousal episodes in the hibernating ground squirrel

Hypothermia is commonly used to restrict organ damage during preservation of tissue, but does not offer complete protection. Organ damage after reperfusion/rewarming is amongst others caused by an impairment of vascular properties, particularly endothelium-dependent vasodilatation. We hypothesized that hibernating small animals, which frequently cycle through periods of deep cooling (torpor) and full rewarming (arousal), employ specific mechanisms to preserve vascular function after cooling and reperfusion. Therefore we measured contraction of aortic tissue of hibernating European ground squirrels after 24 h and 7 days of torpor, arousal (1.5 h) and in non-hibernating animals. To assess the role of nitric oxide (NO), experiments were performed in the absence and presence of the NO-synthesis inhibitor, L-NMMA (10(-4) M). Maximum contraction to phenylephrine and angiotensin 11 was doubled in 7-days torpid animals without a shift in EC50, compared to the other 3 groups. Maximum contraction to KCl was doubled in 7-days torpid animals compared to the arousal group and non-hibernating animals. Relaxation to acetylcholine (ACh) and sodium nitrite in phenylephrine precontracted rings did not differ between groups. In the presence of L-NMMA, the maximum of concentration-response curves for all three vasoconstrictors was increased by about 30% in the arousal group, but unaffected in other groups. L-NNMA completely inhibited ACh-induced relaxation in 24-h torpid animals and non-hibernating animals, but only partially in 7-days torpid animals and in the arousal group. From this we conclude that vascular adaptation proceeds during torpor. Further, increased contractility of aortic tissue during long torpor returns to normal within 1.5 hours of arousal, which is associated with an increased basal NO synthesis. In addition, involvement of NO in agonist-mediated relaxation differs between the various stages of hibernation. Thus, hibernating animals have effectively developed mechanisms to preserve vascular function after cooling and rewarming. (C) 2002 Elsevier Science Inc. All rights reserved

Hydrogen-poor superluminous stellar explosions

Supernovae (SNe) are stellar explosions driven by gravitational or thermonuclear energy, observed as electromagnetic radiation emitted over weeks or more. In all known SNe, this radiation comes from internal energy deposited in the outflowing ejecta by either radioactive decay of freshly-synthesized elements (typically 56Ni), stored heat deposited by the explosion shock in the envelope of a supergiant star, or interaction between the SN debris and slowly-moving, hydrogen-rich circumstellar material. Here we report on a new class of luminous SNe whose observed properties cannot be explained by any of these known processes. These include four new SNe we have discovered, and two previously unexplained events (SN 2005ap; SCP 06F6) that we can now identify as members. These SNe are all ~10 times brighter than SNe Ia, do not show any trace of hydrogen, emit significant ultra-violet (UV) flux for extended periods of time, and have late-time decay rates which are inconsistent with radioactivity. Our data require that the observed radiation is emitted by hydrogen-free material distributed over a large radius (~10^15 cm) and expanding at high velocities (>10^4 km s^-1). These long-lived, UV-luminous events can be observed out to redshifts z>4 and offer an excellent opportunity to study star formation in, and the interstellar medium of, primitive distant galaxies.Comment: Accepted to Nature. Press embargoed until 2011 June 8, 18:00 U

Impact of Space Weather on Climate and Habitability of Terrestrial Type Exoplanets

The current progress in the detection of terrestrial type exoplanets has opened a new avenue in the characterization of exoplanetary atmospheres and in the search for biosignatures of life with the upcoming ground-based and space missions. To specify the conditions favorable for the origin, development and sustainment of life as we know it in other worlds, we need to understand the nature of astrospheric, atmospheric and surface environments of exoplanets in habitable zones around G-K-M dwarfs including our young Sun. Global environment is formed by propagated disturbances from the planet-hosting stars in the form of stellar flares, coronal mass ejections, energetic particles, and winds collectively known as astrospheric space weather. Its characterization will help in understanding how an exoplanetary ecosystem interacts with its host star, as well as in the specification of the physical, chemical and biochemical conditions that can create favorable and/or detrimental conditions for planetary climate and habitability along with evolution of planetary internal dynamics over geological timescales. A key linkage of (astro) physical, chemical, and geological processes can only be understood in the framework of interdisciplinary studies with the incorporation of progress in heliophysics, astrophysics, planetary and Earth sciences. The assessment of the impacts of host stars on the climate and habitability of terrestrial (exo)planets will significantly expand the current definition of the habitable zone to the biogenic zone and provide new observational strategies for searching for signatures of life. The major goal of this paper is to describe and discuss the current status and recent progress in this interdisciplinary field and to provide a new roadmap for the future development of the emerging field of exoplanetary science and astrobiology.Comment: 206 pages, 24 figures, 1 table; Review paper. International Journal of Astrobiology (2019

Biosignals reflect pair-dynamics in collaborative work : EDA and ECG study of pair-programming in a classroom environment

Collaboration is a complex phenomenon, where intersubjective dynamics can greatly affect the productive outcome. Evaluation of collaboration is thus of great interest, and can potentially help achieve better outcomes and performance. However, quantitative measurement of collaboration is difficult, because much of the interaction occurs in the intersubjective space between collaborators. Manual observation and/or self-reports are subjective, laborious, and have a poor temporal resolution. The problem is compounded in natural settings where task-activity and response-compliance cannot be controlled. Physiological signals provide an objective mean to quantify intersubjective rapport (as synchrony), but require novel methods to support broad deployment outside the lab. We studied 28 student dyads during a self-directed classroom pair-programming exercise. Sympathetic and parasympathetic nervous system activation was measured during task performance using electrodermal activity and electrocardiography. Results suggest that (a) we can isolate cognitive processes (mental workload) from confounding environmental effects, and (b) electrodermal signals show role-specific but correlated affective response profiles. We demonstrate the potential for social physiological compliance to quantify pair-work in natural settings, with no experimental manipulation of participants required. Our objective approach has a high temporal resolution, is scalable, non-intrusive, and robust.Peer reviewe

A Methodological Framework for the Evaluation of Syndromic Surveillance Systems: A Case Study of England

Background: Syndromic surveillance complements traditional public health surveillance by collecting and analysing health indicators in near real time. The rationale of syndromic surveillance is that it may detect health threats faster than traditional surveillance systems permitting more timely, and hence potentially more effective public health action. The effectiveness of syndromic surveillance largely relies on the methods used to detect aberrations. Very few studies have evaluated the performance of syndromic surveillance systems and consequently little is known about the types of events that such systems can and cannot detect. Methods: We introduce a framework for the evaluation of syndromic surveillance systems that can be used in any setting based upon the use of simulated scenarios. For a range of scenarios this allows the time and probability of to be determined and uncertainty is fully incorporated. In addition, we demonstrate how such a framework can model the benefits of increases in the number of centres reporting syndromic data and also determine the minimum size of outbreaks that can or cannot be detected. Here, we demonstrate its utility using simulations of national influenza outbreaks and localised outbreaks of cryptosporidiosis. Results: Influenza outbreaks are consistently detected with larger outbreaks being detected in a more timely manner. Small cryptosporidiosis outbreaks (<1000 symptomatic individuals) are unlikely to be detected. We also demonstrate the advantages of having multiple syndromic data streams (e.g. emergency attendance data, telephone helpline data, general practice consultation data) as different streams are able to detect different types outbreaks with different efficacy (e.g. emergency attendance data are useful for the detection of pandemic influenza but not for outbreaks of cryptosporidiosis). We also highlight that for any one disease, the utility of data streams may vary geographically, and that the detection ability of syndromic surveillance varies seasonally (e.g. an influenza outbreak starting in July is detected sooner than one starting later in the year). We argue that our framework constitutes a useful tool for public health emergency preparedness in multiple settings. Conclusions: The proposed framework allows the exhaustive evaluation of any syndromic surveillance system and constitutes a useful tool for emergency preparedness and response

A molecular and antigenic survey of H5N1 highly pathogenic avian influenza virus isolates from smallholder duck farms in Central Java, Indonesia during 2007-2008

Background: Indonesia is one of the countries most severely affected by H5N1 highly pathogenic avian influenza (HPAI) virus in terms of poultry and human health. However, there is little information on the diversity of H5N1 viruses circulating in backyard farms, where chickens and ducks often intermingle. In this study, H5N1 virus infection occurring in 96 smallholder duck farms in central Java, Indonesia from 2007-2008 was investigated and the molecular and antigenic characteristics of H5N1 viruses isolated from these farms were analysed

PageMan: An interactive ontology tool to generate, display, and annotate overview graphs for profiling experiments

BACKGROUND: Microarray technology has become a widely accepted and standardized tool in biology. The first microarray data analysis programs were developed to support pair-wise comparison. However, as microarray experiments have become more routine, large scale experiments have become more common, which investigate multiple time points or sets of mutants or transgenics. To extract biological information from such high-throughput expression data, it is necessary to develop efficient analytical platforms, which combine manually curated gene ontologies with efficient visualization and navigation tools. Currently, most tools focus on a few limited biological aspects, rather than offering a holistic, integrated analysis. RESULTS: Here we introduce PageMan, a multiplatform, user-friendly, and stand-alone software tool that annotates, investigates, and condenses high-throughput microarray data in the context of functional ontologies. It includes a GUI tool to transform different ontologies into a suitable format, enabling the user to compare and choose between different ontologies. It is equipped with several statistical modules for data analysis, including over-representation analysis and Wilcoxon statistical testing. Results are exported in a graphical format for direct use, or for further editing in graphics programs. PageMan provides a fast overview of single treatments, allows genome-level responses to be compared across several microarray experiments covering, for example, stress responses at multiple time points. This aids in searching for trait-specific changes in pathways using mutants or transgenics, analyzing development time-courses, and comparison between species. In a case study, we analyze the results of publicly available microarrays of multiple cold stress experiments using PageMan, and compare the results to a previously published meta-analysis. PageMan offers a complete user's guide, a web-based over-representation analysis as well as a tutorial, and is freely available at . CONCLUSION: PageMan allows multiple microarray experiments to be efficiently condensed into a single page graphical display. The flexible interface allows data to be quickly and easily visualized, facilitating comparisons within experiments and to published experiments, thus enabling researchers to gain a rapid overview of the biological responses in the experiments