460 research outputs found
On the relationships between G-preinvex functions and semistrictly G-preinvex functions
AbstractA new class of functions, termed semistrictly G-preinvex functions, is introduced in this paper. The relationships between semistrictly G-preinvex functions and G-preinvex functions are investigated under mild assumptions. Our results improve and extend the existing ones in the literature
Vector Meson Propagator and Baryon Current Conservation
If baryons couple only with -mesons, one found the baryon spectral
function may be negative. We show this unacceptable result is caused by the
-terms in the -meson propagator. Their contribution may
not vanish in approximate calculations which violate the baryon current
conserves. A rule is suggested, by which the calculated baryon spectral
function is well behaved.Comment: 9 pages (LaTeX file), 3 figures (PostScript file
Coupled Dyson-Schwinger Equations and Effects of Self-Consistency
Using the model as an effective tool, the effects of
self-consistency are studied in some detail. A coupled set of Dyson-Schwinger
equations for the renormalized baryon and meson propagators in the model is solved self-consistently according to the dressed
Hartree-Fock scheme, where the hadron propagators in both the baryon and meson
self-energies are required to also satisfy this coupled set of equations. It is
found that the self-consistency affects the baryon spectral function
noticeably, if only the interaction with mesons is considered.
However, there is a cancellation between the effects due to the and
mesons and the additional contribution of mesons makes the
above effect insignificant. In both the and cases the
effects of self-consistency on meson spectral function are perceptible, but
they can nevertheless be taken account of without a self-consistent
calculation. Our study indicates that to include the meson propagators in the
self-consistency requirement is unnecessary and one can stop at an early step
of an iteration procedure to obtain a good approximation to the fully
self-consistent results of all the hadron propagators in the model, if an
appropriate initial input is chosen. Vertex corrections and their effects on
ghost poles are also studied.Comment: 20 pages (include 5 tables), 17 figures (PostScript file
Age differences in the prevalence of physical aggression among 5- to 11-year-old Canadian boys and girls
Global Incidence and mortality of oesophageal cancer and their correlation with socioeconomic indicators temporal patterns and trends in 41 countries
Oesophageal cancers (adenocarcinomas [AC] and squamous cell carcinomas [SCC]) are characterized by high incidence/mortality in many countries. We aimed to delineate its global incidence and mortality, and studied whether socioeconomic development and its incidence rate were correlated. The age-standardized rates (ASRs) of incidence and mortality of this medical condition in 2012 for 184 nations from the GLOBOCAN database; national databases capturing incidence rates, and the WHO mortality database were examined. Their correlations with two indicators of socioeconomic development were evaluated. Joinpoint regression analysis was used to generate trends. The ratio between the ASR of AC and SCC was strongly correlated with HDI (r = 0.535 [men]; r = 0.661 [women]) and GDP (r = 0.594 [men]; r = 0.550 [women], both p < 0.001). Countries that reported the largest reduction in incidence in male included Poland (Average Annual Percent Change [AAPC] = −7.1, 95%C.I. = −12,−1.9) and Singapore (AAPC = −5.8, 95%C.I. = −9.5,−1.9), whereas for women the greatest decline was seen in Singapore (AAPC = −12.3, 95%C.I. = −17.3,−6.9) and China (AAPC = −5.6, 95%C.I. = −7.6,−3.4). The Philippines (AAPC = 4.3, 95%C.I. = 2,6.6) and Bulgaria (AAPC = 2.8, 95%C.I. = 0.5,5.1) had a significant mortality increase in men; whilst Columbia (AAPC = −6.1, 95%C.I. = −7.5,−4.6) and Slovenia (AAPC = −4.6, 95%C.I. = −7.9,−1.3) reported mortality decline in women. These findings inform individuals at increased risk for primary prevention
The association between distal findings and proximal colorectal neoplasia: a systematic review and meta-analysis
Objectives:
Whether screening participants with distal hyperplastic polyps (HPs) detected by flexible sigmoidoscopy (FS) should be followed by subsequent colonoscopy is controversial. We evaluated the association between distal HPs and proximal neoplasia (PN)/advanced proximal neoplasia (APN) in asymptomatic, average-risk patients.
Methods:
We searched Ovid Medline, EMBASE, and the Cochrane Library from inception to 30 June 2016 and included all screening studies that examined the relationship between different distal findings and PN/APN. Data were independently extracted by two reviewers with disagreements resolved by a third reviewer. We pooled absolute risks and odds ratios (ORs) with a random effects meta-analysis. Seven subgroup analyses were performed according to study characteristics. Heterogeneity was characterized with theI2 statistics.
Results:
We analyzed 28 studies (104,961 subjects). When compared with normal distal findings, distal HP was not associated with PN (OR=1.16, 95% confidence interval (CI)=0.89–1.51,P=0.14,I2=40%) or APN (OR=1.09, 95% CI=0.87–1.36,P=0.39,I2=5%), while subjects with distal non-advanced or advanced adenoma had higher odds of PN/APN. Higher odds of PN/APN were observed for more severe distal lesions. Weaker association between distal and proximal findings was noticed in studies with higher quality, larger sample size, population-based design, and more stringent endoscopy quality-control measures. The Egger’s regression tests showed allP>0.05.
Conclusions:
Distal HP is not associated with PN/APN in asymptomatic screening population when compared with normal distal findings. Hence, the presence of distal HP alone detected by FS does not automatically indicate colonoscopy referral for all screening participants, as other risk factors of PN/APN should be considered
Epitaxially strained [001]-(PbTiO)(PbZrO) superlattice and PbTiO from first principles
The effect of layer-by-layer heterostructuring and epitaxial strain on
lattice instabilities and related ferroelectric properties is investigated from
first principles for the [001]-(PbTiO)(PbZrO) superlattice and
pure PbTiO on a cubic substrate. The results for the superlattice show an
enhancement of the stability of the monoclinic r-phase with respect to pure
PbTiO. Analysis of the lattice instabilities of the relaxed centrosymmetric
reference structure computed within density functional perturbation theory
suggests that this results from the presence of two unstable zone-center modes,
one confined in the PbTiO layer and one in the PbZrO layer, which
produce in-plane and normal components of the polarization, respectively. The
zero-temperature dielectric response is computed and shown to be enhanced not
only near the phase boundaries, but throughout the r-phase. Analysis of the
analogous calculation for pure PbTiO is consistent with this
interpretation, and suggests useful approaches to engineering the dielectric
properties of artificially structured perovskite oxides.Comment: 8 pages, 5 figure
Healthcare needs, experiences, and treatment burden in primary care patients with multimorbidity:an evaluation of process of care from patients' perspectives
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