465 research outputs found
Varenicline versus transdermal nicotine patch for smoking cessation: results from a randomised open-label trial
Gravitational wave astronomy
The first decade of the new millenium should see the first direct detections
of gravitational waves. This will be a milestone for fundamental physics and it
will open the new observational science of gravitational wave astronomy. But
gravitational waves already play an important role in the modeling of
astrophysical systems. I review here the present state of gravitational
radiation theory in relativity and astrophysics, and I then look at the
development of detector sensitivity over the next decade, both on the ground
(such as LIGO) and in space (LISA). I review the sources of gravitational waves
that are likely to play an important role in observations by first- and
second-generation interferometers, including the astrophysical information that
will come from these observations. The review covers some 10 decades of
gravitational wave frequency, from the high-frequency normal modes of neutron
stars down to the lowest frequencies observable from space. The discussion of
sources includes recent developments regarding binary black holes, spinning
neutron stars, and the stochastic background.Comment: 29 pages, 2 figures, as submitted for special millenium issue of
Classical and Quantum Gravit
Myocardial fibrosis in asymptomatic and symptomatic chronic severe primary mitral regurgitation and relationship to tissue characterisation and left ventricular function on cardiovascular magnetic resonance
Background: Myocardial fbrosis occurs in end-stage heart failure secondary to mitral regurgitation (MR), but it is not
known whether this is present before onset of symptoms or myocardial dysfunction. This study aimed to characterise
myocardial fbrosis in chronic severe primary MR on histology, compare this to tissue characterisation on cardiovascular magnetic resonance (CMR) imaging, and investigate associations with symptoms, left ventricular (LV) function, and
exercise capacity.
Methods: Patients with class I or IIa indications for surgery underwent CMR and cardiopulmonary exercise testing. LV
biopsies were taken at surgery and the extent of fbrosis was quantifed on histology using collagen volume fraction
(CVFmean) compared to autopsy controls without cardiac pathology.
Results: 120 consecutive patients (64±13 years; 71% male) were recruited; 105 patients underwent MV repair
while 15 chose conservative management. LV biopsies were obtained in 86 patients (234 biopsy samples in total).
MR patients had more fbrosis compared to 8 autopsy controls (median: 14.6% [interquartile range 7.4â20.3] vs. 3.3%
[2.6â6.1], P<0.001); this diference persisted in the asymptomatic patients (CVFmean 13.6% [6.3â18.8], P<0.001), but
severity of fbrosis was not signifcantly higher in NYHA II-III symptomatic MR (CVFmean 15.7% [9.9â23.1] (P=0.083).
Fibrosis was patchy across biopsy sites (intraclass correlation 0.23, 95% CI 0.08â0.39, P=0.001). No signifcant relationships were identifed between CVFmean and CMR tissue characterisation [native T1, extracellular volume (ECV)
or late gadolinium enhancement] or measures of LV function [LV ejection fraction (LVEF), global longitudinal strain
(GLS)]. Although the range of ECV was small (27.3±3.2%), ECV correlated with multiple measures of LV function (LVEF:
Rho=â0.22, P=0.029, GLS: Rho=0.29, P=0.003), as well as NTproBNP (Rho=0.54, P<0.001) and exercise capacity
(%PredVO2max: R=â0.22, P=0.030). Conclusions: Patients with chronic primary MR have increased fbrosis before the onset of symptoms. Due to the
patchy nature of fbrosis, CMR derived ECV may be a better marker of global myocardial status.
Clinical trial registration Mitral FINDER study; Clinical Trials NCT02355418, Registered 4 February 2015, https://clinicaltr
ials.gov/ct2/show/NCT0235541
The Search for Gravitational Waves
Experiments aimed at searching for gravitational waves from astrophysical
sources have been under development for the last 40 years, but only now are
sensitivities reaching the level where there is a real possibility of
detections being made within the next five years. In this article a history of
detector development will be followed by a description of current detectors
such as LIGO, VIRGO, GEO 600, TAMA 300, Nautilus and Auriga. Preliminary
results from these detectors will be discussed and related to predicted
detection rates for some types of sources. Experimental challenges for detector
design are introduced and discussed in the context of detector developments for
the future.Comment: 21 pages, 7 figures, accepted J. Phys. B: At. Mol. Opt. Phy
Observation of the Dynamic Beta Effect at CESR with CLEO
Using the silicon strip detector of the CLEO experiment operating at the
Cornell Electron-positron Storage Ring (CESR), we have observed that the
horizontal size of the luminous region decreases in the presence of the
beam-beam interaction from what is expected without the beam-beam interaction.
The dependence on the bunch current agrees with the prediction of the dynamic
beta effect. This is the first direct observation of the effect.Comment: 9 page uuencoded postscript file, postscritp file also available
through http://w4.lns.cornell.edu/public/CLNS, submitted to Phys. Rev.
Retarding field energy analyser ion current calibration and transmission
International audienceAccurate measurement of ion current density and ion energy distributions (IED) is often critical for plasma processes in both industrial and research settings. Retarding field energy analyzers (RFEA) have been used to measure IEDs because they are considered accurate, relatively simple and cost effective. However, their usage for critical measurement of ion current density is less common due to difficulties in estimating the proportion of incident ion current reaching the current collector through the RFEA retarding grids. In this paper an RFEA has been calibrated to measure ion current density from an ion beam at pressures ranging from 0.5 to 50.0 mTorr. A unique method is presented where the currents generated at each of the retarding grids and the RFEA upper face are measured separately, allowing the reduction in ion current to be monitored and accounted for at each stage of ion transit to the collector. From these I-V measurements a physical model is described. Subsequently, a mathematical description is extracted which includes parameters to account for grid transmissions, upper face secondary electron emission and collisionality. Pressure-dependant calibration factors can be calculated from least mean square best fits of the collector current to the model allowing quantitative measurement of ion current density
The Surgical Infection Society revised guidelines on the management of intra-abdominal infection
Background: Previous evidence-based guidelines on the management of intra-abdominal infection (IAI) were published by the Surgical Infection Society (SIS) in 1992, 2002, and 2010. At the time the most recent guideline was released, the plan was to update the guideline every five years to ensure the timeliness and appropriateness of the recommendations.
Methods: Based on the previous guidelines, the task force outlined a number of topics related to the treatment of patients with IAI and then developed key questions on these various topics. All questions were approached using general and specific literature searches, focusing on articles and other information published since 2008. These publications and additional materials published before 2008 were reviewed by the task force as a whole or by individual subgroups as to relevance to individual questions. Recommendations were developed by a process of iterative consensus, with all task force members voting to accept or reject each recommendation. Grading was based on the GRADE (Grades of Recommendation Assessment, Development, and Evaluation) system; the quality of the evidence was graded as high, moderate, or weak, and the strength of the recommendation was graded as strong or weak. Review of the document was performed by members of the SIS who were not on the task force. After responses were made to all critiques, the document was approved as an official guideline of the SIS by the Executive Council.
Results: This guideline summarizes the current recommendations developed by the task force on the treatment of patients who have IAI. Evidence-based recommendations have been made regarding risk assessment in individual patients; source control; the timing, selection, and duration of antimicrobial therapy; and suggested approaches to patients who fail initial therapy. Additional recommendations related to the treatment of pediatric patients with IAI have been included.
Summary: The current recommendations of the SIS regarding the treatment of patients with IAI are provided in this guideline
A physician survey reveals differences in management of idiopathic pulmonary hemosiderosis
- âŠ