255 research outputs found
Vascular Responses to High-Intensity Battling Rope Exercise between the Sexes
The purpose of the study was to assess high-intensity battling rope exercise (HI-BRE) on hemodynamics, pulse wave reflection and arterial stiffness during recovery and between sexes. Twenty-three young, healthy resistance-trained individuals (men: n = 13; women: n = 10) were assessed for all measures at Rest, as well as 10-, 30-, and 60-minutes following HI-BRE. A one-way repeated measures ANOVA was used to analyze the effects of HI-BRE across time (Rest, 10, 30, and 60-minutes) on all dependent variables. Significant main effects were analyzed using paired t-tests with a Sidak correction factor. Significance was accepted a priori at p 0.05. There were significant reductions in hemodynamic measures of diastolic blood pressure (BP) in women, but not men following HI-BRE at 30 minutes. Further, measures of pulse wave reflection, specifically those of the augmentation index (AIx) and wasted left ventricular energy (ÎEw), were significantly increased in both men and women for 60 minutes, but changes were significantly attenuated in women suggesting less ventricular work. There were also significant increases in arterial stiffness in regard to the aorta and common carotid artery that were fully recovered by 30 and 60 minutes, respectively with no differences between men and women. Thus, the primary findings of this study suggest that measures of hemodynamics and pulse wave reflection are collectively altered for at least 60 minutes following HI-BRE, with women having attenuated responses compared to men
Inactivation of the Pta-AckA Pathway Causes Cell Death in \u3ci\u3eStaphylococcus aureus\u3c/i\u3e
During growth under conditions of glucose and oxygen excess, Staphylococcus aureus predominantly accumulates acetate in the culture medium, suggesting that the phosphotransacetylase-acetate kinase (Pta-AckA) pathway plays a crucial role in bacterial fitness. Previous studies demonstrated that these conditions also induce the S. aureus CidR regulon involved in the control of cell death. Interestingly, the CidR regulon is comprised of only two operons, both encoding pyruvate catabolic enzymes, suggesting an intimate relationship between pyruvate metabolism and cell death. To examine this relationship, we introduced ackA and pta mutations in S. aureus and tested their effects on bacterial growth, carbon and energy metabolism, cid expression, and cell death. Inactivation of the Pta-AckA pathway showed a drastic inhibitory effect on growth and caused accumulation of dead cells in both pta and ackA mutants. Surprisingly, inactivation of the Pta-AckA pathway did not lead to a decrease in the energy status of bacteria, as the intracellular concentrations of ATP, NAD+, and NADH were higher in the mutants. However, inactivation of this pathway increased the rate of glucose consumption, led to a metabolic block at the pyruvate node, and enhanced carbon flux through both glycolysis and the tricarboxylic acid (TCA) cycle. Intriguingly, disruption of the Pta-AckA pathway also induced the CidR regulon, suggesting that activation of alternative pyruvate catabolic pathways could be an important survival strategy for the mutants. Collectively, the results of this study demonstrate the indispensable role of the Pta-AckA pathway in S. aureus for maintaining energy and metabolic homeostasis during overflow metabolism
Optical Spectropolarimetry of the GRB 020813 Afterglow
The optical afterglow of gamma-ray burst 020813 was observed for 3 hours with
the LRIS spectropolarimeter at the Keck-I telescope, beginning 4.7 hours after
the burst was detected by HETE-2. The spectrum reveals numerous metal
absorption lines that we identify with two systems at z=1.223 and z=1.255. We
also detect an O II 3727 emission line at z=1.255 and we identify this galaxy
as the likely host of the GRB. After a correction for Galactic interstellar
polarization, the optical afterglow has a linear polarization of 1.8-2.4%
during 4.7-7.9 hours after the burst. A measurement of p = 0.80% +/- 0.16% on
the following night by Covino et al. demonstrates significant polarization
variability over the next 14 hours. The lack of strong variability in the
position angle of linear polarization indicates that the magnetic field in the
jet is likely to be globally ordered rather than composed of a number of
randomly oriented cells. Within the framework of afterglow models with
collimated flows, the relatively low observed polarization suggests that the
magnetic field components perpendicular and parallel to the shock front are
only different by about 20%.Comment: To appear in ApJ Letters. 6 pages including 2 figure
An Unbiased Survey of 500 Nearby Stars for Debris Disks: A JCMT Legacy Program
We present the scientific motivation and observing plan for an upcoming
detection survey for debris disks using the James Clerk Maxwell Telescope. The
SCUBA-2 Unbiased Nearby Stars (SUNS) Survey will observe 500 nearby main
sequence and sub-giant stars (100 of each of the A, F, G, K and M spectral
classes) to the 850 micron extragalactic confusion limit to search for evidence
of submillimeter excess, an indication of circumstellar material. The survey
distance boundaries are 8.6, 16.5, 22, 25 and 45 pc for M, K, G, F and A stars,
respectively, and all targets lie between the declinations of -40 deg to 80
deg. In this survey, no star will be rejected based on its inherent properties:
binarity, presence of planetary companions, spectral type or age. This will be
the first unbiased survey for debris disks since IRAS. We expect to detect ~125
debris disks, including ~50 cold disks not detectable in current shorter
wavelength surveys. A substantial amount of complementary data will be required
to constrain the temperatures and masses of discovered disks. High resolution
studies will likely be required to resolve many of the disks. Therefore, these
systems will be the focus of future observational studies using a variety of
observatories to characterize their physical properties. For non-detected
systems, this survey will set constraints (upper limits) on the amount of
circumstellar dust, of typically 200 times the Kuiper Belt mass, but as low as
10 times the Kuiper Belt mass for the nearest stars in the sample
(approximately 2 pc).Comment: 11 pages, 7 figures (3 color), accepted by the Publications of the
Astronomical Society of the Pacifi
Full-field MRI measurements of in-vivo positional brain shift reveal the significance of intra-cranial geometry and head orientation for stereotactic surgery
Positional brain shift (PBS), the sagging of the brain under the effect of gravity, is comparable in magnitude to the margin of error for the success of stereotactic interventions (⌠1 mm). This non-uniform shift due to slight differences in head orientation can lead to a significant discrepancy between the planned and the actual location of surgical targets. Accurate in-vivo measurements of this complex deformation are critical for the design and validation of an appropriate compensation to integrate into neuronavigational systems. PBS arising from prone-to-supine change of head orientation was measured with magnetic resonance imaging on 11 young adults. The full-field displacement was extracted on a voxel-basis via digital volume correlation and analysed in a standard reference space. Results showed the need for target-specific correction of surgical targets, as a significant displacement ranging from 0.52 to 0.77 mm was measured at surgically relevant structures. Strain analysis further revealed local variability in compressibility: anterior regions showed expansion (both volume and shape change), whereas posterior regions showed small compression, mostly dominated by shape change. Finally, analysis of correlation demonstrated the potential for further patient- and intervention-specific adjustments, as intra-cranial breadth and head tilt correlated with PBS reaching statistical significance
Gravitational Waves From Known Pulsars: Results From The Initial Detector Era
We present the results of searches for gravitational waves from a large selection of pulsars using data from the most recent science runs (S6, VSR2 and VSR4) of the initial generation of interferometric gravitational wave detectors LIGO (Laser Interferometric Gravitational-wave Observatory) and Virgo. We do not see evidence for gravitational wave emission from any of the targeted sources but produce upper limits on the emission amplitude. We highlight the results from seven young pulsars with large spin-down luminosities. We reach within a factor of five of the canonical spin-down limit for all seven of these, whilst for the Crab and Vela pulsars we further surpass their spin-down limits. We present new or updated limits for 172 other pulsars (including both young and millisecond pulsars). Now that the detectors are undergoing major upgrades, and, for completeness, we bring together all of the most up-to-date results from all pulsars searched for during the operations of the first-generation LIGO, Virgo and GEO600 detectors. This gives a total of 195 pulsars including the most recent results described in this paper.United States National Science FoundationScience and Technology Facilities Council of the United KingdomMax-Planck-SocietyState of Niedersachsen/GermanyAustralian Research CouncilInternational Science Linkages program of the Commonwealth of AustraliaCouncil of Scientific and Industrial Research of IndiaIstituto Nazionale di Fisica Nucleare of ItalySpanish Ministerio de Economia y CompetitividadConselleria d'Economia Hisenda i Innovacio of the Govern de les Illes BalearsNetherlands Organisation for Scientific ResearchPolish Ministry of Science and Higher EducationFOCUS Programme of Foundation for Polish ScienceRoyal SocietyScottish Funding CouncilScottish Universities Physics AllianceNational Aeronautics and Space AdministrationOTKA of HungaryLyon Institute of Origins (LIO)National Research Foundation of KoreaIndustry CanadaProvince of Ontario through the Ministry of Economic Development and InnovationNational Science and Engineering Research Council CanadaCarnegie TrustLeverhulme TrustDavid and Lucile Packard FoundationResearch CorporationAlfred P. Sloan FoundationAstronom
LSST Science Book, Version 2.0
A survey that can cover the sky in optical bands over wide fields to faint
magnitudes with a fast cadence will enable many of the exciting science
opportunities of the next decade. The Large Synoptic Survey Telescope (LSST)
will have an effective aperture of 6.7 meters and an imaging camera with field
of view of 9.6 deg^2, and will be devoted to a ten-year imaging survey over
20,000 deg^2 south of +15 deg. Each pointing will be imaged 2000 times with
fifteen second exposures in six broad bands from 0.35 to 1.1 microns, to a
total point-source depth of r~27.5. The LSST Science Book describes the basic
parameters of the LSST hardware, software, and observing plans. The book
discusses educational and outreach opportunities, then goes on to describe a
broad range of science that LSST will revolutionize: mapping the inner and
outer Solar System, stellar populations in the Milky Way and nearby galaxies,
the structure of the Milky Way disk and halo and other objects in the Local
Volume, transient and variable objects both at low and high redshift, and the
properties of normal and active galaxies at low and high redshift. It then
turns to far-field cosmological topics, exploring properties of supernovae to
z~1, strong and weak lensing, the large-scale distribution of galaxies and
baryon oscillations, and how these different probes may be combined to
constrain cosmological models and the physics of dark energy.Comment: 596 pages. Also available at full resolution at
http://www.lsst.org/lsst/sciboo
The Surviving Sepsis Campaign: results of an international guideline-based performance improvement program targeting severe sepsis
Objective: The Surviving Sepsis Campaign (SSC or âthe Campaignâ) developed guidelines for management of severe sepsis and septic shock. A performance improvement initiative targeted changing clinical behavior (process improvement) via bundles based on key SSC guideline recommendations on process improvement and patient outcomes. Design and setting: A multifaceted intervention to facilitate compliance with selected guideline recommendations in the ICU, ED, and wards of individual hospitals and regional hospital networks was implemented voluntarily in the US, Europe, and South America. Elements of the guidelines were âbundledâ into two sets of targets to be completed within 6Â h and within 24Â h. An analysis was conducted on data submitted from January 2005 through March 2008. Main results: Data from 15,022 subjects at 165 sites were analyzed to determine the compliance with bundle targets and association with hospital mortality. Compliance with the entire resuscitation bundle increased linearly from 10.9% in the first site quarter to 31.3% by the end of 2Â years (PÂ <Â 0.0001). Compliance with the entire management bundle started at 18.4% in the first quarter and increased to 36.1% by the end of 2Â years (PÂ =Â 0.008). Compliance with all bundle elements increased significantly, except for inspiratory plateau pressure, which was high at baseline. Unadjusted hospital mortality decreased from 37 to 30.8% over 2Â years (PÂ =Â 0.001). The adjusted odds ratio for mortality improved the longer a site was in the Campaign, resulting in an adjusted absolute drop of 0.8% per quarter and 5.4% over 2Â years (95% CI, 2.5â8.4%). Conclusions: The Campaign was associated with sustained, continuous quality improvement in sepsis care. Although not necessarily cause and effect, a reduction in reported hospital mortality rates was associated with participation. The implications of this study may serve as an impetus for similar improvement efforts.Electronic supplementary material The online version of this article (doi:10.1007/s00134-009-1738-3) contains supplementary material, which is available to authorized users
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