507 research outputs found
Squeezed gluon vacuum and the global colour model of QCD
We discuss how the vacuum model of Celenza and Shakin with a squeezed gluon
condensate can explain the existence of an infrared singular gluon propagator
frequently used in calculations within the global colour model. In particular,
it reproduces a recently proposed QCD-motivated model where low energy chiral
parameters were computed as a function of a dynamically generated gluon mass.
We show how the strength of the confining interaction of this gluon propagator
and the value of the physical gluon condensate may be connected.Comment: 13 pages, LaTe
Landau-gauge condensates from the quark propagator on the lattice
We compute the dimension-2 condensate, , and the dimension-4 mixed
condensate, , from the recent quenched lattice results for the
quark propagator in the Landau gauge. We fit the lattice data to the Operator
Product Expansion in the "fiducial" region 1.2 GeV < Q < 3 GeV. Our result for
the dynamical gluon mass at the scale of 10 GeV^2 is m_A=600-650 MeV, in
agreement with independent determinations. For the mixed Landau gauge
condensate of dimension-4 we get alpha_s = (-0.11 +/- 0.03)
GeV^4. This value is an order of magnitude larger than the gluon
condensate.Comment: 4 pages, 3 figures, references adde
Community-associated Clostridium difficile infection in emergency department patients in Western Australia
Clostridium difficile infection (CDI) is primarily associated with hospitalised patients, however, community-associated CDI (CA-CDI) has increased in Australia. We aimed to investigate the epidemiology and outcomes of CA-CDI cases presenting to hospital emergency departments in Western Australia (WA). A retrospective case-control study of CA-CDI cases presenting at six emergency departments in WA from July 2013 to June 2014 was performed. Clinical signs, recent medication, hospitalisations and potential risk factors for CA-CDI were investigated for cases (n = 34) and unmatched controls (n = 62) who were infected with another gastrointestinal pathogen, including Campylobacter spp., Salmonella spp., Aeromonas spp., Shigella sonnei and Escherichia coli O157. Elevated white cell count (31.3% vs 8.2%, p < 0.01), female gender (67.6% vs 41.9%, p < 0.05), age =65 years (41.2% vs 21.0%, p < 0.05) and antimicrobial use in the previous month (41.2% vs 11.3%, p < 0.01) were significantly more frequent among cases compared to controls. After multivariable analysis, antibiotic use (odds ratio 8.49, 95% confidence interval 2.75–26.21) and age =65 years (3.03, 1.05–8.75) were significantly associated with CA-CDI. Ribotype (RT) 014/020 was most common (40.7%) among 27 C. difficile isolates followed by RTs 002 (14.8%), 001, 056 and 244 (all 7.4%). CA-CDI was associated with advanced age and recent antibiotic use compared to those infected with other gastrointestinal pathogens. RT 014 has also recently been found at high prevalence in public lawn spaces, and previously RT 014 strains from humans and pigs in Australia were closely genetically related, suggesting CA-CDI may be linked with these community reservoirs
Risk factors of overweight and obesity among preschool children with different ethnic background
partially_open5noIn this study, we evaluated the risk factors associated with overweight and obesity in 2,640 preschool children in Italy taking into account the ethnic background of the parents. Height and weight were measured and BMI was calculated. Personal and lifestyle data for the children (birth weight, type of breastfeeding, sleep duration, skipping breakfast, snacking, physical activity) and parents (ethnicity, educational level, occupation, weight, height) were collected by means of a questionnaire. Italian and Other European children generally showed the highest percentage of normal weight, while the other ethnic groups presented a greater imbalance. Overweight and obesity were high in African males, who also presented high birth weight. Breastfeeding was most common, although formula feeding was significantly higher in Italians than in immigrants. Immigrants, particularly males, tended to skip breakfast more than Italians. Physical activity was significantly higher in Italians than in immigrants. In the parents, underweight was particularly high in Italian and Other mothers. African parents had high rates of overweight and obesity and a low educational level. The most common profession was worker for the fathers and housewife for the mothers, with the exception of Italians in which clerical work prevailed. Multiple linear regression analysis showed that the BMI of children was closely related to the BMI of the parents and the birth weight. Hence, these are the most informative parameters in preventing obesity.openToselli S; Zaccagni L; Celenza F; Albertini A; Gualdi-Russo EToselli, S; Zaccagni, Luciana; Celenza, F; Albertini, A; Gualdi, Emanuel
QCD Sum Rules Description of Nucleons in Asymmetric Nuclear Matter
We calculate the nucleon parameters in isospin asymmetric nuclear matter
using the QCD sum rules. The nucleon self-energies are expressed in terms of
the in-medium values of QCD condensates. The simple approximate expressions for
the self-energies are obtained in terms of these condensates. Relation between
successive inclusion of the condensates and the meson-exchange picture of the
nucleon interaction with medium is analyzed. The values of the self-energies
and of the symmetry energy agree with those obtained by the methods of nuclear
physics.Comment: 40 pages, 6 figure
On the Relativistic Description of the Nucleus
We discuss a relativistic theory of the atomic nuclei in the framework of the
hamiltonian formalism and of the mesonic model of the nucleus. Attention is
paid to the translational invariance of the theory. Our approach is centered on
the concept of spectral amplitude, a function in the Dirac spinor space. We
derive a Lorentz covariant equation for the latter, which requires as an input
the baryon self-energy. For this we either postulate the most general
Lorentz-Poincar\'e invariant expression or perform a calculation via a
Bethe-Salpeter equation starting from a nucleon-nucleus interaction. We discuss
the features of the nuclear spectrum obtained in the first instance. Finally
the general constraints the self-energy should satisfy because of analyticity
and Poincar\'e covariance are discussed
Use of serum lactate levels to predict survival for patients with out-of-hospital cardiac arrest: A cohort study
Objectives: We examined the association of serum lactate levels and early lactate clearance with survival to hospital discharge for patients suffering an out-of-hospital cardiac arrest (OHCA). Methods: A retrospective cohort analysis was performed of patients with OHCA transported by ambulance to two adult tertiary hospitals in Perth, Western Australia. Exclusion criteria were traumatic cardiac arrest, return of spontaneous circulation prior to the arrival of the ambulance, age less than 18 years and no serum lactate levels recorded. Serum lactate levels recorded for up to 48h post-arrest were obtained from the hospital clinical information system, and lactate clearance over 48h was calculated. Descriptive and logistic regression analyses were conducted. Results: There were 518 patients with lactate values, of whom 126 (24.3%) survived to hospital discharge. Survivors and non-survivors had different mean initial lactate levels (mean±SD 6.9±4.7 and 12.2±5.5mmol/L, respectively; P<0.001). Lactate clearance was higher in survivors. Lactate levels for non-survivors did not decrease below 2mmol/L until at least 30h after the ambulance call. Conclusion: In OHCA patients who had serum lactate levels measured, both lower initial serum lactate and early lactate clearance in the first 48h following OHCA were associated with increased likelihood of survival. However, the use of lactate in isolation as a predictor of survival or neurological outcome is not recommended. Prospective studies that minimise selection bias are required to determine the clinical utility of serum lactate levels in OHCA patients. © 2016 Australasian College for Emergency Medicine and Australasian Society for Emergency Medicine
Squeezed Gluon Condensate and Quark Confinement in the Global Color Model of QCD
We discuss how the presence of a squeezed gluon vacuum might lead to quark
confinement in the framework of the global colour model of QCD. Using reduced
phase space quantization of massive vector theory we construct a Lorentz
invariant and colourless squeezed gluon condensate and show that it induces a
permanent, nonlocal quark interaction (delta-function in 4-momentum space),
which according to Munczek and Nemirovsky might lead to quark confinement. Our
approach makes it possible to relate the strength of this effective confining
quark interaction to the strength of the physical gluon condensate.Comment: 18 pages LaTeX, to appear in Int. J. Mod. Phys.
Derivation and assessment of strong coupling core-particle model from the Kerman-Klein-D\"onau-Frauendorf theory
We review briefly the fundamental equations of a semi-microscopic
core-particle coupling method that makes no reference to an intrinsic system of
coordinates. We then demonstrate how an intrinsic system can be introduced in
the strong coupling limit so as to yield a completely equivalent formulation.
It is emphasized that the conventional core-particle coupling calculation
introduces a further approximation that avoids what has hitherto been the most
time-consuming feature of the full theory, and that this approximation can be
introduced either in the intrinsic system, the usual case, or in the laboratory
system, our preference. A new algorithm is described for the full theory that
largely removes the difference in complexity between the two types of
calculation. Comparison of the full and approximate theories for some
representative cases provides a basis for the assessment of the accuracy of the
traditional approach. We find that for well-deformed nuclei, e.g. 157Gd and
157Tb, the core-coupling method and the full theory give similar results.Comment: revtex, 3 figures(postscript), submitted to Phys.Rev.
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