3,716 research outputs found
Universality in the Electroproduction of Vector Mesons
We study universality in the electroproduction of vector mesons using a
unified nonperturbative approach which has already proved to reproduce
extremely well the available experimental data. In this framework, after the
extraction of factors that are specific of each vector meson, we arrive at a
reduced integrated elastic cross section which is universal. Our calculations
suggest a finite infrared behavior for the strong coupling constant.Comment: 22 pages, 10 figure
Association of occupational heat exposure and colorectal cancer in the MCC-Spain study
Objective Heat exposure and heat stress/strain is a concern for many workers. There is increasing interest in
potential chronic health effects of occupational heat exposure, including cancer risk. We examined potential
associations of occupational heat exposure and colorectal cancer (CRC) risk in a large Spanish multi-caseâcontrol
study.
Methods We analyzed data on 1198 histologically confirmed CRC cases and 2690 frequency-matched controls.
The Spanish job-exposure matrix, MatEmEsp, was used to assign heat exposure estimates to the lifetime occupations
of participants. Three exposure indices were assessed: ever versus never exposed, cumulative exposure and
duration (years). We estimated odds ratios (OR) and 95% confidence intervals (CI) using unconditional logistic
regression adjusting for potential confounders.
Results Overall, there was no association of ever, compared with never, occupational heat exposure and CRC
(OR 1.09, 95% CI 0.92â1.29). There were also no associations observed according to categories of cumulative
exposure or duration, and there was no evidence for a trend. There was no clear association of ever occupational
heat exposure and CRC in analysis conducted among either men or women when analyzed separately. Positive
associations were observed among women in the highest categories of cumulative exposure (OR 1.81, 95% CI
1.09â3.03) and duration (OR 2.89, 95% CI 1.50â5.59) as well as some evidence for a trend (P<0.05).
Conclusion Overall, this study provides no clear evidence for an association between occupational heat exposure
and CRC.The study was partially funded by the "Accion Transversal del Cancer", approved by the Spanish Ministry Council on 11 October 2007, by the Instituto de Salud Carlos III-FEDER (PI08/1770, PI08/1359, PI09/00773, PI09/01286, PI09/01903, PI09/02078, PI09/01662, PI11/01403, PI11/01889, PI12/00265), the FundaciĂłn MarquĂ©s de Valdecilla (API 10/09), the Junta de Castilla y LeĂłn (LE22A10-2), the ConsejerĂa de Salud of the Junta de AndalucĂa (2009-S0143), the Conselleria de Sanitat of the Generalitat Valenciana (AP_061/10), the Recercaixa (2010ACUP 00310), the Regional government
of the Basque Country, the ConsejerĂa de Sanidad de la RegiĂłn de Murcia, the European Commission grants
FOOD-CT-2006â036224-HIWATE, the Spanish Association Against Cancer (AECC) Scientific Foundation, the Catalan Government DURSI grant 2014SGR647, the support of the Secretariat for Universities and Research of the Ministry of Business and Knowledge of the Government of Catalonia (2017SGR1085), the FundaciĂłn Caja de Ahorros de Asturias and by the University of Oviedo. MCT is funded by a RamĂłn y Cajal fellowship (RYC-2017-01892) from the Spanish Ministry of Science, Innovation and Universities and co-funded by the
European Social Fund. We acknowledge support from
the Spanish Ministry of Science and Innovation through the âCentro de Excelencia Severo Ochoa 2019-2023â Program (CEX2018-000806-S), and support from the Generalitat de Catalunya through the CERCA Program. Statistical assistance provided by Ana Espinosa Morano was greatly appreciated
Relaxation paths for single modes of vibrations in isolated molecules
A numerical simulation of vibrational excitation of molecules was devised,
and used to excite computational models of common molecules into a prescribed,
pure, normal vibration mode in the ground electronic state, with varying,
controlable energy content. The redistribution of this energy (either
non-chaotic or irreversible IVR) within the isolated, free molecule is then
followed in time with a view to determining the coupling strength between
modes. This work was triggered by the need to predict the general characters of
the infrared spectra to be expected from molecules in interstellar space, after
being excited by photon absorption or reaction with a radical. It is found that
IVR from a pure normal mode is very "restricted" indeed at energy contents of
one mode quantum or so. However, as this is increased, or when the excitation
is localized, our approach allows us to isolate, describe and quantify a number
of interesting phenomena, known to chemists and in non-linear mechanics, but
difficult to demonstrate experimentally: frequency dragging, mode locking or
quenching or, still, instability near a potential surface crossing, the first
step to generalized chaos as the energy content per mode is increased.Comment: 25 pages, 15 figures; accepted by J. Atom. Phys.
Chemotactic Collapse and Mesenchymal Morphogenesis
We study the effect of chemotactic signaling among mesenchymal cells. We show
that the particular physiology of the mesenchymal cells allows one-dimensional
collapse in contrast to the case of bacteria, and that the mesenchymal
morphogenesis represents thus a more complex type of pattern formation than
those found in bacterial colonies. We finally compare our theoretical
predictions with recent in vitro experiments
Photon deflection by a Coulomb field in noncommutative QED
In noncommutative QED photons present self-interactions in the form of triple
and quartic interactions. The triple interaction implies that, even though the
photon is electrically neutral, it will deflect when in the presence of an
electromagnetic field. If detected, such deflection would be an undoubted
signal of noncommutative space-time. In this work we derive the general
expression for the deflection of a photon by any electromagnetic field. As an
application we consider the case of the deflection of a photon by an external
static Coulomb field.Comment: 07 pages, some typos corrected, accepted for publication in JP
Signals of Supersymmetric Lepton Flavor Violation at the LHC
In a generic supersymmetric extension of the Standard Model, there will be
lepton flavor violation at a neutral gaugino vertex due to misalignment between
the lepton Yukawa couplings and the slepton soft masses. Sleptons produced at
the LHC through the cascade decays of squarks and gluinos can give a sizable
number of events with 4 leptons. This channel could give a clean signature of
supersymmetric lepton flavor violation under conditions which are identified.Comment: 21 page
Evaluating matrix elements relevant to some Lorenz violating operators
Carlson, Carone and Lebed have derived the Feynman rules for a consistent
formulation of noncommutative QCD. The results they obtained were used to
constrain the noncommutativity parameter in Lorentz violating noncommutative
field theories. However, their constraint depended upon an estimate of the
matrix element of the quark level operator (gamma.p - m) in a nucleon. In this
paper we calculate the matrix element of (gamma.p - m), using a variety of
confinement potential models. Our results are within an order of magnitude
agreement with the estimate made by Carlson et al. The constraints placed on
the noncommutativity parameter were very strong, and are still quite severe
even if weakened by an order of magnitude.Comment: 4 pages, 3 figures, RevTex, minor change
Common Mental Disorders
Common mental disorders (CMDs) comprise different types of depression and anxiety. They cause marked emotional distress and interfere with daily function,but do not usually affect insight or cognition. Although usually less disabling than major psychiatric disorders, their higher prevalence means the cumulative cost of CMDs to society is great. The revised Clinical Interview Schedule (CIS-R) has been used on each Adult Psychiatric Morbidity Survey (APMS) in the series to assess six types of CMD: depression, generalised anxiety disorder (GAD), panic disorder, phobias, obsessive compulsive disorder (OCD), and CMD not otherwise specified (CMD-NOS). Many people meet the criteria for more than one CMD. The CIS-R is also used to produce a score that reflects overall severity of CMD symptoms. âą Since 2000, there has been a slight but steady increase in the proportion of women with CMD symptoms (as indicated by a CIS-R score of 12 or more), but overall stability at this level among men. The increase in prevalence was evident mostly at the more severe end of the scale (CIS-R score 18 or more). âą Since the last survey (2007), increases in CMD have also been evident among late midlife men and women (aged 55 to 64), and approached significance in young women (aged 16 to 24). âą The gap in rates of CMD symptoms between young men and women appears to have grown. In 1993, 16 to 24 year old women (19.2%) were twice as likely as 16 to 24 year old men (8.4%) to have symptoms of CMD (CIS-R score 12 or more). In 2014, CMD symptoms were about three times more common in women of that age (26.0%) than men (9.1%). âą CMDs were more prevalent in certain groups of the population. These included Black women, adults under the age of 60 who lived alone, women who lived in large households, adults not in employment, those in receipt of benefits and those who smoked cigarettes. These associations are in keeping with increased social disadvantage and poverty being associated with higher risk of CMD. Most people identified by the CIS-R with a CMD also perceived themselves to have a CMD. This was not the case for most of the other disorders assessed in the APMS. âą While most of these people had been diagnosed with a mental disorder by a professional, the disorders they reported having been diagnosed with tended to be âdepressionâ or âpanic attacksâ. However, the disorder most commonly identified by the CIS-R was GAD. This difference may reflect the language and terminology used by people when discussing their mental health with a professional
Umbrella review and metaâanalysis of antiplatelet therapy for peripheral artery disease
Background
The literature on antiplatelet therapy for peripheral artery disease has historically been summarized inconsistently, leading to conflict between international guidelines. An umbrella review and metaâanalysis was performed to summarize the literature, allow assessment of competing safety risks and clinical benefits, and identify weak areas for future research.
Methods
MEDLINE, Embase, DARE, PROSPERO and Cochrane databases were searched from inception until January 2019. All metaâanalyses of antiplatelet therapy in peripheral artery disease were included. Quality was assessed using AMSTAR scores, and GRADE analysis was used to quantify the strength of evidence. Data were pooled using randomâeffects models.
Results
Twentyâeight metaâanalyses were included. Thirtyâthree clinical outcomes and 41 antiplatelet comparisons in 72â181 patients were analysed. Highâquality evidence showed that antiplatelet monotherapy reduced nonâfatal strokes (3 (95 per cent c.i. 0 to 6) fewer per 1000 patients), In symptomatic patients, it reduced cardiovascular deaths (8 (0 to 16) fewer per 1000 patients), but increased the risk of major bleeding (7 (3 to 14) more events per 1000). In asymptomatic patients, monotherapy reduced nonâfatal strokes (5 (0 to 8) fewer per 1000), but had no other clinical benefit. Dual antiplatelet therapy caused more major bleeding after intervention than monotherapy (37 (8 to 102) more events per 1000), with very lowâquality evidence of improved endovascular patency (risk ratio 4·00, 95 per cent c.i. 0·91 to 17·68).
Conclusion
Antiplatelet monotherapy has minimal clinical benefit for asymptomatic peripheral artery disease, and limited benefit for symptomatic disease, with a clear risk of major bleeding. There is a lack of evidence to guide antiplatelet prescribing after peripheral endovascular intervention
Entropy Measures of Electroencephalograms towards the Diagnosis of Psychogenic Non-Epileptic Seizures
Psychogenic non-epileptic seizures (PNES) may resemble epileptic seizures but are not caused by epileptic activity. However, the analysis of electroencephalogram (EEG) signals with entropy algorithms could help identify patterns that differentiate PNES and epilepsy. Furthermore, the use of machine learning could reduce the current diagnosis costs by automating classification. The current study extracted the approximate sample, spectral, singular value decomposition, and Renyi entropies from interictal EEGs and electrocardiograms (ECG)s of 48 PNES and 29 epilepsy subjects in the broad, delta, theta, alpha, beta, and gamma frequency bands. Each feature-band pair was classified by a support vector machine (SVM), k-nearest neighbour (kNN), random forest (RF), and gradient boosting machine (GBM). In most cases, the broad band returned higher accuracy, gamma returned the lowest, and combining the six bands together improved classifier performance. The Renyi entropy was the best feature and returned high accuracy in every band. The highest balanced accuracy, 95.03%, was obtained by the kNN with Renyi entropy and combining all bands except broad. This analysis showed that entropy measures can differentiate between interictal PNES and epilepsy with high accuracy, and improved performances indicate that combining bands is an effective improvement for diagnosing PNES from EEGs and ECGs
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