1,950 research outputs found
New U(1) Gauge Symmetry of Quarks and Leptons
Instead of anchoring the seesaw mechanism with the conventional heavy
right-handed neutrino singlet, a small Majorana neutrino mass may be obtained
just as well with the addition of a heavy triplet of leptons per family to the
minimal standard model of particle interactions. The resulting model is shown
to have the remarkable property of accommodating a new U(1) symmetry which is
anomaly-free and may thus be gauged. There are many possible phenomenological
consequences of this proposal which may be already relevant in explaining one
or two recent potential experimental discrepancies.Comment: minor word changes, to appear in MPL
Impact of diagnosis of diabetes on health-related quality of life among high risk individuals: the Diabetes Prevention Program outcomes study
Purpose
The purpose of this study is to assess if diagnosis of type 2 diabetes affected health-related quality of life (HRQoL) among participants in the Diabetes Prevention Program/Diabetes Prevention Program Outcome Study and changes with treatment or diabetes duration.
Methods
3,210 participants with pre-diabetes were randomized to metformin (MET), intensive lifestyle intervention (ILS), or placebo (PLB). HRQoL was assessed using the SF-36 including: (1) 8 SF-36 subscales; (2) the physical component (PCS) and mental component summary (MCS) scores; and (3) the SF-6D. The sample was categorized by diabetes free versus diagnosed. For diagnosed subgroup, mean scores in the diabetes-free period, at 6 months, 2, 4 and 6 years post-diagnosis, were compared.
Results
PCS and SF-6D scores declined in all participants in all treatment arms (P <.001). MCS scores did not change significantly in any treatment arm regardless of diagnosis. ILS participants reported a greater decrease in PCS scores at 6 months post-diagnosis (P <.001) and a more rapid decline immediately post-diagnosis in SF-6D scores (P = .003) than the MET or PLB arms. ILS participants reported a significant decrease in the social functioning subscale at 6 months (P <.001) and two years (P <.001) post-diagnosis.
Conclusions
Participants reported a decline in measures of overall health state (SF-6D) and overall physical HRQoL, whether or not they were diagnosed with diabetes during the study. There was no change in overall mental HRQoL. Participants in the ILS arm with diabetes reported a more significant decline in some HRQoL measures than those in the MET and PLB arms that developed diabetes
Orthogonal methods based ant colony search for solving continuous optimization problems
Research into ant colony algorithms for solving continuous optimization problems forms one of the most
significant and promising areas in swarm computation. Although traditional ant algorithms are designed for combinatorial
optimization, they have shown great potential in solving a wide range of optimization problems, including continuous
optimization. Aimed at solving continuous problems effectively, this paper develops a novel ant algorithm termed "continuous orthogonal ant colony" (COAC), whose pheromone deposit mechanisms would enable ants to search for
solutions collaboratively and effectively. By using the orthogonal design method, ants in the feasible domain can explore
their chosen regions rapidly and e±ciently. By implementing an "adaptive regional radius" method, the proposed
algorithm can reduce the probability of being trapped in local optima and therefore enhance the global search capability and accuracy. An elitist strategy is also employed to reserve the most valuable points. The performance of the COAC is
compared with two other ant algorithms for continuous optimization of API and CACO by testing seventeen functions
in the continuous domain. The results demonstrate that the proposed COAC algorithm outperforms the others
Tests of the Standard Model Using Muon Polarization Asymmetries in Kaon Decays
We have examined the physics and the experimental feasibility of studying
various kaon decay processes in which the polarization of a muon in the final
state is measured. Valuable information on CP violation, the quark mixing (CKM)
matrix, and new physics can be obtained from such measurements. We have
considered muon polarization in K_L to mu+ mu- and K to pi mu+ mu- decays.
Although the effects are small, or difficult to measure because of the small
branching ratios involved, these studies could provide clean measurements of
the CKM parameters. The experimental difficulty appears comparable to the
observation of K to pi nu barnu. New sources of physics, involving non-standard
CP violation, could produce effects observable in these measurements. Limits
from new results on the neutron and electron electric dipole moment, and
epsilon-prime over epsilon in neutral kaon decays, do not eliminate certain
models that could contribute to the signal. A detailed examination of muon
polarization out of the decay plane in KMU3 and radiative KMU2 decays also
appears to be of interest. With current kaon beams and detector techniques, it
is possible to measure the T-violating polarization for KMU3 with uncertainties
approaching 0.0001. This level of sensitivity would provide an interesting
probe of new physics.Comment: 24 pages, 3 figures, To be published in the International Journal of
Modern Physics
A quark model framework for the study of nuclear medium effects
A quark-model framework for studying nuclear medium effects on nucleon
resonances is described and applied here to pion photoproduction on the
deuteron, which is the simplest composite nucleon system and serves as a first
test case. Pion photoproduction on nuclei is discussed within a chiral
constituent quark model in which the quark degrees of freedom are explicitly
introduced through an effective chiral Lagrangian for the
quark-pseudoscalar-meson coupling. The advantage of this model is that a
complete set of nucleon resonances can be systematically included with a
limited number of parameters. Also, the systematic description of the nucleon
and its resonances at quark level allows us to self-consistently relate the
nuclear medium's influence on the baryon properties to the intrinsic dynamic
aspects of the baryons. As the simplest composite nucleus, the deuteron
represents the first application of this effective theory for meson
photoproduction on light nuclei. The influence of the medium on the transition
operators for a free nucleon is investigated in the Delta resonance region. No
evidence is found for a change of the Delta properties in the pion
photoproduction reaction on the deuteron since the nuclear medium here involves
just one other nucleon and the low binding energy implies low nuclear density.
However, we show that the reaction mechanism is in principle sensitive to
changes of Delta properties that would be produced by the denser nuclear medium
of heavier nuclei through the modification of the quark model parameters.Comment: Revtex, 8 pages, 4 figure
Unparticle Searches Through Compton Scattering
We investigate the effects of unparticles on Compton scattering, e gamma -> e
gamma based on a future e^+e^- linear collider such as the CLIC. For different
polarization configurations, we calculate the lower limits of the unparticle
energy scale Lambda_U for a discovery reach at the center of mass energies
sqrt(s)=0.5 TeV- 3 TeV. It is shown that, especially, for smaller values of the
mass dimension d, (1 <d <1.3), and for high energies and luminosities of the
collider these bounds are very significant. As a stringent limit, we find
Lambda_U>80 TeV for d<1.3 at sqrt(s)=3 TeV, and 1 ab^(-1) integrated luminosity
per year, which is comparable with the limits calculated from other low and
high energy physics implications.Comment: Table 1 and 2 have been combined as Table 1, references updated,
minor typos have been correcte
An Investigation of Hadronization Mechanism at Factory
We briefly review the hadronization pictures adopted in the LUND String
Fragmentation Model(LSFM), Webber Cluster Fragmentation Model(WCFM) and Quark
Combination Model(QCM), respectively. Predictions of hadron multiplicity,
baryon to meson ratios and baryon-antibaryon flavor correlations, especially
related to heavy hadrons at factory obtained by LSFM and QCM are
reported.Comment: 18 pages, 6 figures. accepted by Sci China Phys Mech Astro
Exploring residual risk for diabetes and microvascular disease in the Diabetes Prevention Program Outcomes Study (DPPOS)
Aim
Approximately half of the participants in the Diabetes Prevention Outcomes Study (DPPOS) had diabetes after 15 years of follow-up, whereas nearly all the others remained with pre-diabetes. We examined whether formerly unexplored factors in the DPPOS coexisted with known risk factors that posed additional risk for, or protection from, diabetes as well as microvascular disease.
Methods
Cox proportional hazard models were used to examine predictors of diabetes. Sequential modelling procedures considered known and formerly unexplored factors. We also constructed models to determine whether the same unexplored factors that associated with progression to diabetes also predicted the prevalence of microvascular disease. Hazard ratios (HR) are per standard deviation change in the variable.
Results
In models adjusted for demographics and known diabetes risk factors, two formerly unknown factors were associated with risk for both diabetes and microvascular disease: number of medications taken (HR = 1.07, 95% confidence intervals (95% CI) 1.03 to 1.12 for diabetes; odds ratio (OR) = 1.10, 95% CI 1.04 to 1.16 for microvascular disease) and variability in HbA1c (HR = 1.02, 95% CI 1.01 to 1.03 for diabetes; OR = 1.06, 95% CI 1.04 to 1.09 for microvascular disease per sd). Total comorbidities increased risk for diabetes (HR = 1.10, 95% CI 1.04 to 1.16), whereas higher systolic (OR = 1.22, 95% CI 1.13 to 1.31) and diastolic (OR = 1.14, 95% CI 1.05 to 1.22) blood pressure, as well as the use of anti-hypertensives (OR = 1.41, 95% CI 1.23 to 1.62), increased risk of microvascular disease.
Conclusions
Several formerly unexplored factors in the DPPOS predicted additional risk for diabetes and/or microvascular disease – particularly hypertension and the use of anti-hypertensive medications – helping to explain some of the residual disease risk in participants of the DPPOS
Using biomarkers to predict TB treatment duration (Predict TB): a prospective, randomized, noninferiority, treatment shortening clinical trial
Background : By the early 1980s, tuberculosis treatment was shortened from 24 to 6 months, maintaining relapse rates of 1-2%. Subsequent trials attempting shorter durations have failed, with 4-month arms consistently having relapse rates of 15-20%. One trial shortened treatment only among those without baseline cavity on chest x-ray and whose month 2 sputum culture converted to negative. The 4-month arm relapse rate decreased to 7% but was still significantly worse than the 6-month arm (1.6%, P<0.01). We hypothesize that PET/CT characteristics at baseline, PET/CT changes at one month, and markers of residual bacterial load will identify patients with tuberculosis who can be cured with 4 months (16 weeks) of standard treatment.Methods: This is a prospective, multicenter, randomized, phase 2b, noninferiority clinical trial of pulmonary tuberculosis participants. Those eligible start standard of care treatment. PET/CT scans are done at weeks 0, 4, and 16 or 24. Participants who do not meet early treatment completion criteria (baseline radiologic severity, radiologic response at one month, and GeneXpert-detectable bacilli at four months) are placed in Arm A (24 weeks of standard therapy). Those who meet the early treatment completion criteria are randomized at week 16 to continue treatment to week 24 (Arm B) or complete treatment at week 16 (Arm C). The primary endpoint compares the treatment success rate at 18 months between Arms B and C.Discussion: Multiple biomarkers have been assessed to predict TB treatment outcomes. This study uses PET/CT scans and GeneXpert (Xpert) cycle threshold to risk stratify participants. PET/CT scans are not applicable to global public health but could be used in clinical trials to stratify participants and possibly become a surrogate endpoint. If the Predict TB trial is successful, other immunological biomarkers or transcriptional signatures that correlate with treatment outcome may be identified. TRIAL REGISTRATION: NCT02821832
Chiral 2pi exchange at order four and peripheral NN scattering
We calculate the impact of the complete set of two-pion exchange
contributions at chiral order four (also known as
next-to-next-to-next-to-leading order, N3LO) on peripheral partial waves of
nucleon-nucleon scattering. Our calculations are based upon the analytical
studies by Kaiser. It turns out that the contribution of order four is
substantially smaller than the one of order three, indicating convergence of
the chiral expansion. We compare the prediction from chiral pion-exchange with
the corresponding one from conventional meson-theory as represented by the Bonn
Full Model and find, in general, good agreement. Our calculations provide a
sound basis for investigating the issue whether the low-energy constants
determined from pi-N lead to reasonable predictions for NN.Comment: 22 pages RevTex including 11 figure
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