1,962 research outputs found
Jet p_T Resummation in Higgs Production at NNLL'+NNLO
We present predictions for Higgs production via gluon fusion with a p_T veto
on jets and with the resummation of jet-veto logarithms at NNLL'+$NNLO order.
These results incorporate explicit O(alphas^2) calculations of soft and beam
functions, which include the dominant dependence on the jet radius R. In
particular the NNLL' order accounts for the correct boundary conditions for the
N3LL resummation, for which the only unknown ingredients are higher-order
anomalous dimensions. We use scale variations in a factorization theorem in
both rapidity and virtuality space to estimate the perturbative uncertainties,
accounting for both higher fixed-order corrections as well as higher-order
towers of jet-p_T logarithms. This formalism also predicts the correlations in
the theory uncertainty between the exclusive 0-jet and inclusive 1-jet bins. At
the values of R used experimentally, there are important corrections due to jet
algorithm clustering that include logarithms of R. Although we do not sum
logarithms of R, we do include an explicit contribution in our uncertainty
estimate to account for higher-order jet clustering logarithms. Precision
predictions for this H+0-jet cross section and its theoretical uncertainty are
an integral part of Higgs analyses that employ jet binning.Comment: 24 pages, 11 figure
Atrial fibrillation and survival in colorectal cancer
BACKGROUND: Survival in colorectal cancer may correlate with the degree of systemic inflammatory response to the tumour. Atrial fibrillation may be regarded as an inflammatory complication. We aimed to determine if atrial fibrillation is a prognostic factor in colorectal cancer. PATIENTS AND METHODS: A prospective colorectal cancer patient database was cross-referenced with the hospital clinical-coding database to identify patients who had underwent colorectal cancer surgery and were in atrial fibrillation pre- or postoperatively. RESULTS: A total of 175 patients underwent surgery for colorectal cancer over a two-year period. Of these, 13 patients had atrial fibrillation pre- or postoperatively. Atrial fibrillation correlated with worse two-year survival (p = 0.04; log-rank test). However, in a Cox regression analysis, atrial fibrillation was not significantly associated with survival. CONCLUSION: The presence or development of atrial fibrillation in patients undergoing surgery for colorectal cancer is associated with worse overall survival, however it was not found to be an independent factor in multivariate analysis
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Role of carotid duplex imaging in carotid screening programmes - an overview.
BACKGROUND: Stroke is the third most common cause of death in the UK and the largest single cause of severe disability. Each year more than 110,000 people in England suffer from a stroke which costs the National Health Service (NHS) over GBP2.8 billion. Thus, it is imperative that patients at risk be screened for underlying carotid artery atherosclerosis. AIM: To assess the role of carotid ultrasound in different carotid screening programmes. METHODS: A literature overview was carried out by using PubMed search engine, to identify different carotid screening programmes that had used ultrasound scan as a screening tool. RESULTS: It appears that the carotid ultrasound is an effective method for screening carotid artery disease in community as it effectively predicts the presence of stenosis with high accuracy. There is a need for primary care to recommend high risk patients for regular screening, to reduce stroke and transient ischemic attack (TIA) related morbidity and mortality. CONCLUSION: Screening programmes using carotid ultrasonography contribute to public health awareness and promotion which in long term could potentially benefit in disease prevention and essentially promote better standards of healthcare.RIGHTS : This article is licensed under the BioMed Central licence at http://www.biomedcentral.com/about/license which is similar to the 'Creative Commons Attribution Licence'. In brief you may : copy, distribute, and display the work; make derivative works; or make commercial use of the work - under the following conditions: the original author must be given credit; for any reuse or distribution, it must be made clear to others what the license terms of this work are
Histiocytoid cardiomyopathy and microphthalmia with linear skin defects syndrome: phenotypes linked by truncating variants in NDUFB11
Variants in NDUFB11, which encodes a structural component of complex I of the mitochondrial respiratory chain (MRC), were recently independently reported to cause histiocytoid cardiomyopathy (histiocytoid CM) and microphthalmia with linear skin defects syndrome (MLS syndrome). Here we report an additional case of histiocytoid CM, which carries a de novo nonsense variant in NDUFB11 (ENST00000276062.8: c.262C > T; p.[Arg88*]) identified using whole-exome sequencing (WES) of a family trio. An identical variant has been previously reported in association with MLS syndrome. The case we describe here lacked the diagnostic features of MLS syndrome, but a detailed clinical comparison of the two cases revealed significant phenotypic overlap. Heterozygous variants in HCCS (which encodes an important mitochondrially targeted protein) and COX7B, which, like NDUFB11, encodes a protein of the MRC, have also previously been identified in MLS syndrome including a case with features of both MLS syndrome and histiocytoid CM. However, a systematic review of WES data from previously published histiocytoid CM cases, alongside four additional cases presented here for the first time, did not identify any variants in these genes. We conclude that NDUFB11 variants play a role in the pathogenesis of both histiocytoid CM and MLS and that these disorders are allelic (genetically related)
Stealth Galaxies in the Halo of the Milky Way
We predict that there is a population of low-luminosity dwarf galaxies
orbiting within the halo of the Milky Way that have surface brightnesses low
enough to have escaped detection in star-count surveys. The overall count of
stealth galaxies is sensitive to the presence (or lack) of a low-mass threshold
in galaxy formation. These systems have luminosities and stellar velocity
dispersions that are similar to those of known ultrafaint dwarf galaxies but
they have more extended stellar distributions (half light radii greater than
about 100 pc) because they inhabit dark subhalos that are slightly less massive
than their higher surface brightness counterparts. As a result, the typical
peak surface brightness is fainter than 30 mag per square arcsec. One
implication is that the inferred common mass scale for Milky Way dwarfs may be
an artifact of selection bias. If there is no sharp threshold in galaxy
formation at low halo mass, then ultrafaint galaxies like Segue 1 represent the
high-mass, early forming tail of a much larger population of objects that could
number in the hundreds and have typical peak circular velocities of about 8
km/s and masses within 300 pc of about 5 million solar masses. Alternatively,
if we impose a low-mass threshold in galaxy formation in order to explain the
unexpectedly high densities of the ultrafaint dwarfs, then we expect only a
handful of stealth galaxies in the halo of the Milky Way. A complete census of
these objects will require deeper sky surveys, 30m-class follow-up telescopes,
and more refined methods to identify extended, self-bound groupings of stars in
the halo.Comment: 12 pages, 7 figures, accepted by ApJ. Several crucial references
added and the discussion has been expanded. Conclusions are unchanged
Non-global Structure of the O({\alpha}_s^2) Dijet Soft Function
High energy scattering processes involving jets generically involve matrix
elements of light- like Wilson lines, known as soft functions. These describe
the structure of soft contributions to observables and encode color and
kinematic correlations between jets. We compute the dijet soft function to
O({\alpha}_s^2) as a function of the two jet invariant masses, focusing on
terms not determined by its renormalization group evolution that have a
non-separable dependence on these masses. Our results include non-global single
and double logarithms, and analytic results for the full set of non-logarithmic
contributions as well. Using a recent result for the thrust constant, we
present the complete O({\alpha}_s^2) soft function for dijet production in both
position and momentum space.Comment: 55 pages, 8 figures. v2: extended discussion of double logs in the
hard regime. v3: minor typos corrected, version published in JHEP. v4: typos
in Eq. (3.33), (3.39), (3.43) corrected; this does not affect the main
result, numerical results, or conclusion
Non-invasive MR imaging of inflammation in a patient with both asymptomatic carotid atheroma and an abdominal aortic aneurysm: a case report.
Inflammation is a recognized risk factor for the vulnerable atherosclerotic plaque. USPIO-enhanced MRI imaging is a promising non-invasive method to identify high-risk atheromatous plaque inflammation in vivo in humans, in which areas of focal signal loss on MR images have been shown to correspond to the location of activated macrophages, typically at the shoulder regions of the plaque. This is the first report in humans describing simultaneous USPIO uptake within atheroma in two different arterial territories and again emphasises that atherosclerosis is a truly systemic disease. With further work, USPIO-enhanced MR imaging may be useful in identifying inflamed vulnerable atheromatous plaques in vivo, so refining patient selection for intervention and allowing appropriate early aggressive pharmacotherapy to prevent plaque rupture.RIGHTS : This article is licensed under the BioMed Central licence at http://www.biomedcentral.com/about/license which is similar to the 'Creative Commons Attribution Licence'. In brief you may : copy, distribute, and display the work; make derivative works; or make commercial use of the work - under the following conditions: the original author must be given credit; for any reuse or distribution, it must be made clear to others what the license terms of this work are
Consistent Factorization of Jet Observables in Exclusive Multijet Cross-Sections
We demonstrate the consistency at the next-to-leading-logarithmic (NLL) level
of a factorization theorem based on Soft-Collinear Effective Theory (SCET) for
jet shapes in e+e- collisions. We consider measuring jet observables in
exclusive multijet final states defined with cone and k_T-type jet algorithms.
Consistency of the factorization theorem requires that the renormalization
group evolution of hard, jet, and soft functions is such that the physical
cross-section is independent of the factorization scale mu. The anomalous
dimensions of the various factorized pieces, however, depend on the color
representation of jets, choice of jet observable, the number of jets whose
shapes are measured, and the jet algorithm, making it highly nontrivial to
satisfy the consistency condition. We demonstrate the intricate cancellations
between anomalous dimensions that occur at the NLL level, so that, up to power
corrections that we identify, our factorization of the jet shape distributions
is consistent for any number of quark and gluon jets, for any number of jets
whose shapes are measured or unmeasured, for any angular size R of the jets,
and for any of the algorithms we consider. Corrections to these results are
suppressed by the SCET expansion parameter lambda (the ratio of soft to
collinear or collinear to hard scales) and in the jet separation measure 1/t^2
= tan^2(R/2)/tan^2(psi/2), where psi is the angular separation between jets.
Our results can be used to calculate a wide variety of jet observables in
multijet final states to NLL accuracy.Comment: 8 pages, 1 figure, uses elsarticle.cls; v2: minor edits, added
reference
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