9,821 research outputs found
Cost-effectiveness of counselling, graded-exercise and usual care for chronic fatigue: evidence from a randomised trial in primary care
Fatigue is common and has been shown to result in high economic costs to society. The aim of this study is to compare the cost-effectiveness of two active therapies, graded-exercise (GET) and counselling (COUN) with usual care plus a self-help booklet (BUC) for people presenting with chronic fatigue
The two components of the SO(3)-character space of the fundamental group of a closed surface of genus 2
We use geometric techniques to explicitly find the topological structure of
the space of SO(3)-representations of the fundamental group of a closed surface
of genus 2 quotient by the conjugation action by SO(3). There are two
components of the space. We will describe the topology of both components and
describe the corresponding SU(2)-character spaces by parametrizing them by
spherical triangles. There is the sixteen to one branch-covering for each
component, and the branch locus is a union of 2-spheres or 2-tori. Along the
way, we also describe the topology of both spaces. We will later relate this
result to future work into higher-genus cases and the SL(3,R)-representations
Diffeomorphisms and families of Fourier-Mukai transforms in mirror symmetry
Assuming the standard framework of mirror symmetry, a conjecture is
formulated describing how the diffeomorphism group of a Calabi-Yau manifold Y
should act by families of Fourier-Mukai transforms over the complex moduli
space of the mirror X. The conjecture generalizes a proposal of Kontsevich
relating monodromy transformations and self-equivalences. Supporting evidence
is given in the case of elliptic curves, lattice-polarized K3 surfaces and
Calabi-Yau threefolds. A relation to the global Torelli problem is discussed.Comment: Approx. 20 pages LaTeX. One reference adde
Stability of Affine G-varieties and Irreducibility in Reductive Groups
Let be a reductive affine algebraic group, and let be an affine
algebraic -variety. We establish a (poly)stability criterion for points
in terms of intrinsically defined closed subgroups of , and
relate it with the numerical criterion of Mumford, and with Richardson and
Bate-Martin-R\"ohrle criteria, in the case . Our criterion builds on a
close analogue of a theorem of Mundet and Schmitt on polystability and allows
the generalization to the algebraic group setting of results of Johnson-Millson
and Sikora about complex representation varieties of finitely presented groups.
By well established results, it also provides a restatement of the non-abelian
Hodge theorem in terms of stability notions.Comment: 29 pages. To appear in Int. J. Math. Note: this version 4 is
identical with version 2 (version 3 is empty
Risk factors which predispose first-time traumatic anterior shoulder dislocations to recurrent instability in adults: a systematic review and meta-analysis
Recurrent instability following a first-time anterior traumatic shoulder dislocation may exceed 26%. We systematically reviewed risk factors which predispose this population to events of recurrence
Uncovering Bugs in Distributed Storage Systems during Testing (not in Production!)
Testing distributed systems is challenging due to multiple sources of nondeterminism. Conventional testing techniques, such as unit, integration and stress testing, are ineffective in preventing serious but subtle bugs from reaching production. Formal techniques, such as TLA+, can only verify high-level specifications of systems at the level of logic-based models, and fall short of checking the actual executable code. In this paper, we present a new methodology for testing distributed systems. Our approach applies advanced systematic testing techniques to thoroughly check that the executable code adheres to its high-level specifications, which significantly improves coverage of important system behaviors. Our methodology has been applied to three distributed storage systems in the Microsoft Azure cloud computing platform. In the process, numerous bugs were identified, reproduced, confirmed and fixed. These bugs required a subtle combination of concurrency and failures, making them extremely difficult to find with conventional testing techniques. An important advantage of our approach is that a bug is uncovered in a small setting and witnessed by a full system trace, which dramatically increases the productivity of debugging
Late-onset bloodstream infection and perturbed maturation of the gastrointestinal microbiota in premature infants
Late-onset bloodstream infection (LO-BSI) is a common complication of prematurity, and lack of timely diagnosis and treatment can have life-threatening consequences. We sought to identify clinical characteristics and microbial signatures in the gastrointestinal microbiota preceding diagnosis of LO-BSI in premature infants.Daily faecal samples and clinical data were collected over two years from 369 premature neonates (<32 weeks gestation). We analysed samples from 22 neonates who developed LO-BSI and 44 matched control infants. Next-generation sequencing of 16S rRNA gene regions amplified by PCR from total faecal DNA was used to characterise the microbiota of faecal samples preceding diagnosis from infants with LO-BSI and controls. Culture of selected samples was undertaken, and bacterial isolates identified using MALDI-TOF. Antibiograms from bloodstream and faecal isolates were compared to explore strain similarity.From the week prior to diagnosis, infants with LO-BSI had higher proportions of faecal aerobes/facultative anaerobes compared to controls. Risk factors for LO-BSI were identified by multivariate analysis. Enterobacteriaceal sepsis was associated with antecedent multiple lines, low birth weight and a faecal microbiota with prominent Enterobacteriaceae. Staphylococcal sepsis was associated with Staphylococcus OTU faecal over-abundance, and the number of days prior to diagnosis of mechanical ventilation and of the presence of centrally-placed lines. In 12 cases, the antibiogram of the bloodstream isolate matched that of a component of the faecal microbiota in the sample collected closest to diagnosis.The gastrointestinal tract is an important reservoir for LO-BSI organisms, pathogens translocating across the epithelial barrier. LO-BSI is associated with an aberrant microbiota, with abundant staphylococci and Enterobacteriaceae and a failure to mature towards predominance of obligate anaerobes
In children 18 years and under, what promotes recurrent shoulder instability after traumatic anterior shoulder dislocation? A systematic review and meta-analysis of risk factors
Background Skeletal maturity and age-related changes in the composition of the glenoid labrum and joint capsule may influence rates of recurrent instability in children. We systematically review risk factors which predispose children to recurrent shoulder instability. Methods The systematic review-concerned studies published before May 2015. Statistical analysis was undertaken to compare rates of recurrence for each extracted risk factor. Pooled ORs were analysed using random effects meta-analysis. Results 6 retrospective cohort studies met the inclusion criteria. 8 risk factors were identified across the studies including age, sex, shoulder dominance and injury side, mechanism of injury, state of physis closure, and Hill-Sachs and Bankart lesions. The rate of recurrent instability was 73%. Children aged 14–18 years were 24 times more likely to experience recurrent instability than children aged 13 years and less (93% vs 40%; OR=24.14, 95% CI (3.71 to 156.99), Z=3.33, p=0.001, I2=6.83%). There was a non-significant trend indicating males were 3.4 times more likely to experience recurrent instability (OR=3.44, 95% CI (0.98 to 12.06), Z=1.93, p=0.053, I2=0%). Analysis of one study found that children with a closed physis are 14 times more likely to experience recurrent instability compared with those with an open physis (OR=14.0, 95% CI (1.46 to 134.25), Z=2.29, p=0.02, I2=0%) . Conclusions Male children aged 14 years and over had the greatest risk of recurrent shoulder instability following a first-time traumatic anterior shoulder dislocation. This meta-analysis summarises a mix of 6 acceptable and poor quality level III retrospective cohort studies. Further examination of this population with blinded prospective cohort studies will assist clinicians in the appropriate management of first-time traumatic anterior shoulder dislocation
On non- solutions to the Seiberg-Witten equations
We show that a previous paper of Freund describing a solution to the
Seiberg-Witten equations has a sign error rendering it a solution to a related
but different set of equations. The non- nature of Freund's solution is
discussed and clarified and we also construct a whole class of solutions to the
Seiberg-Witten equations.Comment: 8 pages, Te
Optical Coronagraphic Spectroscopy of AU Mic: Evidence of Time Variable Colors?
We present coronagraphic long slit spectra of AU Mic's debris disk taken with
the STIS instrument aboard the Hubble Space Telescope (HST). Our spectra are
the first spatially resolved, scattered light spectra of the system's disk,
which we detect at projected distances between approximately 10 and 45 AU. Our
spectra cover a wavelength range between 5200 and 10200 angstroms. We find that
the color of AU Mic's debris disk is bluest at small (12-35 AU) projected
separations. These results both confirm and quantify the findings qualitatively
noted by Krist et al. (2005), and are different than IR observations that
suggested a uniform blue or gray color as a function of projected separation in
this region of the disk. Unlike previous literature that reported the color of
AU Mic's disk became increasingly more blue as a function of projected
separation beyond approximately 30 AU, we find the disk's optical color between
35-45 AU to be uniformly blue on the southeast side of the disk and
decreasingly blue on the northwest side. We note that this apparent change in
disk color at larger projected separations coincides with several fast, outward
moving "features" that are passing through this region of the southeast side of
the disk. We speculate that these phenomenon might be related, and that the
fast moving features could be changing the localized distribution of sub-micron
sized grains as they pass by, thereby reducing the blue color of the disk in
the process. We encourage follow-up optical spectroscopic observations of the
AU Mic to both confirm this result, and search for further modifications of the
disk color caused by additional fast moving features propagating through the
disk.Comment: Accepted by AJ, 13 pages, 8 figures, 1 tabl
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