254 research outputs found
Phase transition of the nucleon-antinucleon plasma at different ratios
We investigate phase transitions for the Walecka model at very high
temperatures. As is well known, depending on the parametrization of this model
and for the particular case of a zero chemical potential (), a first
order phase transition is possible \cite{theis}. We investigate this model for
the case in which . It turns out that, in this situation, phases
with different values of antinucleon-nucleon ratios and net baryon densities
may coexist. We present the temperature versus antinucleon-nucleon ratio as
well as the temperature versus the net baryon density for the coexistence
region. The temperature versus chemical potential phase diagram is also
presented.Comment: 5 pages, 8 figure
Nucleon-nucleon scattering within a multiple subtractive renormalization approach
A methodology to renormalize the nucleon-nucleon interaction, using a
recursive multiple subtraction approach to construct the kernel of the
scattering equation, is presented. We solve the subtracted scattering equation
with the next-leading-order (NLO) and next-to-next-leading-order (NNLO)
interactions. The results are presented for all partial waves up to ,
fitted to low-energy experimental data. In our renormalizaton group invariant
method, when introducing the NLO and NNLO interactions, the subtraction energy
emerges as a renormalization scale and the momentum associated with it comes to
be about the QCD scale (), irrespectively to the partial wave.Comment: Final versio
Expression of Subclinical Atherosclerosis for Different Cardiovascular Risk Factors in Young Populations
INTRODUCTION: Carotid intima-media thickness (cIMT) is considered an early marker for atherosclerosis, but there are few studies on the expression of this marker in younger populations.
OBJECTIVES: To evaluate cIMT in younge patients (aged 30-50 years) and its expression according to cardiovascular risk factors.
METHODS: We analyzed individuals admitted for an invasive cardiac procedure. Normal cIMT was defined as 1.50 mm. Lipid profile, anthropometric parameters, fasting blood glucose and estimated GFR were also determined.
RESULTS: A total of 106 patients were included (59% male), with a mean age of 43 +/- 5 years, 36% with hypertension, 22% smokers, 32% with known hyperlipidemia, 16% with diabetes, 39% under statin therapy and 40% with metabolic syndrome (AHA/NHLBI definition). Mean cIMT was 0.69 +/- 0.26 mm, and was normal in 74% of the patients, thickened in 20% and with atherosclerotic plaques in 6%. cIMT correlated directly with age (r = 0.26, p = 0.007), log fasting glucose (r = 0.21, p = 0.04), and log triglycerides (r = 0.24, p = 0.017), and tended to correlate with the number of components of metabolic syndrome (r = 0.17, p = 0.08). However, on multivariate analysis, only age remained as an independent predictor (r = 0.29, p = 0.005). Diabetic patients had greater cIMT (0.81 +/- 0.22 vs. 0.67 +/- 0.26 mm, p = 0.039) and there was a trend for greater cIMT in those with metabolic syndrome (0.75 +/- 0.29 vs. 0.66 +/- 0.23 mm, p = 0.09). There were no differences for the other risk factors, A higher number of risk factors in a single patient showed a trend for increased cIMT (p = 0.083)
CONCLUSIONS: Age is the only independent determinant of cIMT in a young population. Diabetic patients have greater cIMT and a trend was seen in those with metabolic syndrome, possibly influenced by its relation with diabetes, one of the components of the metabolic syndrome
Nonlinear Klein-Gordon equation and the Bose-Einstein condensation
El interés por la ecuación de Klein-Gordon con diferentes potenciales ha aumentado en los últimos años debido a su posible aplicaciones en CosmologÃa, FÃsica de Hadrones y FÃsica de Altas EnergÃas. En este trabajo, investigamos las soluciones de la ecuación de Klein–Ecuación para bosones bajo la influencia de un potencial externo utilizando el método de Feshbach-Villars. Presentamos resultados detallados en dos casos: el potencial de Coulomb y el potencial armónico. Para el segundo caso, estudiamos los efectos de la auto-interacción de partÃculas dentro de una aproximación de de campo medio. Mostramos que nuestros resultados convergen suavemente a la solución de la ecuación de Schrödinger para los mismos sistemas a medida que disminuyen los efectos relativistas.
En inglés: The interest in the Klein–Gordon equation with different potentials has increased in recent years due to its possible applications in Cosmology, Hadron Physics and High-Energy Physics. In this work, we investigate the solutions of the Klein–Gordon equation for bosons under the influence of an external potential by using the Feshbach–Villars method. We present detailed results for two cases: the Coulombic potential and the harmonic potential. For the latter case, we studied the effects of self-interacting particles by adopting a mean-field approach. We show that our results converge smoothly to the solution of the Schrödinger equation for the same systems as the relativistic effects diminish.FQM-225CNPq-Brazil 304244/2018-0ConsejerÃa de ConocimientoConselho Nacional de Desenvolvimento CientÃfico e TecnológicoFAEPEX 2019/010889-1, 3258/19Investigación y Universidad of the Junta de AndalucÃaJunta de AndalucÃa-ConsejerÃa de EconomÃa y Conocimiento 2014-2020 Operational ProgramFundação de Amparo à Pesquisa do Estado de São Paulo
2021/12954-5Conselho Nacional de Desenvolvimento CientÃfico e Tecnológico
306615/2018-5European Regional Development Fund
RYC-2016-20678, SOMM17/6105/UGRJunta de AndalucÃa
A-FQM-178-UGR18, FQM-225Instituto Nacional de Ciência e Tecnologia: FÃsica Nuclear e Aplicações
2016/17612-7, 464 898/2014-5ConsejerÃa de Conocimiento, Investigación y Universidad, Junta de AndalucÃ
Relationship Between Coronary Disease and Subclinical Hypothyroidism: an Angiographic Study
INTRODUCTION: The definition of subclinical hypothyroidism (SH) is an asymptomatic state in which free thyroxine (T4) is normal and thyroid-stimulating hormone (TSH) levels are elevated. Its relationship with coronary disease is not clear and has been the subject of recent interest. Current evidence is conflicting and there is a lack of studies supported by coronary angiography.
OBJECTIVE: To assess the relationship between SH and the presence and extent of coronary disease diagnosed by angiography.
METHODS: We prospectively studied 354 consecutive patients referred for elective coronary angiography. Those with known thyroid disease, documented coronary disease or previous myocardial infarction were excluded. Fasting blood specimens were collected to measure thyroid hormones, lipid profile, high-sensitivity C-reactive protein, fibrinogen and NT-proBNP. Patients with SH were compared with those without to assess differences in clinical characteristics and biochemical and angiographic results. Significant coronary disease was defined as the presence of at least one lesion with > or = 50% luminal stenosis. Lesions with <50% stenosis were considered minimal.
RESULTS: SH was diagnosed in 32 (9%) patients. Mean age was similar between the groups. There were more women (66% vs. 39%; p=0.003) and atrial fibrillation was more frequent (25% vs. 11%; p=0.016) in the group of patients with SH. There were no significant differences in the other baseline clinical parameters, and blood biochemistry results were similar in the two groups, with the exception of higher levels of NT-proBNP in SH patients, although without statistical significance. The angiographic results were as follows: significant coronary disease (SH 28.1% vs. non-SH 43.8%; p=0.087); three-vessel disease (9.4% vs. 9.9%; p=0.919); two-vessel disease (12.5% vs. 13.4%; p=0.892); single-vessel disease (6.3% vs. 29.5%; p=0.051); minimal lesions (9.4% vs. 10.9%; p=0.794); and no coronary disease (62.4% vs, 45.3%; p=0.064).
CONCLUSION: In this population SH was not associated with the presence or extent of coronary disease diagnosed by coronary angiography
Isolated Cleft of the Anterior Mitral Valve Leaflet
Isolated anterior mitral leaflet cleft (not associated with atrio-ventricular septal defect) is a rare cause of congenital mitral regurgitation, and the treatment consists of direct suturing of the cleft. We present a clinical case with this entity
Does the new International Diabetes Federation Definition of Metabolic Syndrome Improve Prediction of Coronary Artery Disease and Carotid Intima-Media Thickening
BACKGROUND: Metabolic syndrome (MS) is associated with increased incidence of diabetes and atherosclerotic complications. The new definition of the International Diabetes Federation (IDF) increases the population with this entity, compared to the NCEP ATP III definition.
OBJECTIVES: To study the prevalence of coronary artery disease (CAD) and carotid intima-media thickness (IMT) in patients with and without MS, according to the NCEP ATP III and IDF definitions, and the predictive ability of carotid IMT for CAD.
METHODS: We studied 270 consecutive patients admitted for elective coronary angiography due to suspicion of CAD. All patients underwent ultrasound study of the carotid arteries to measure IMT (the highest value between the right and left common carotid arteries was used in the analysis). Coronary stenosis of > or =70% (or 50% for the left main coronary artery) was considered significant.
RESULTS: By the ATP III definition, 14% of the patients had MS, and these patients had a higher prevalence of CAD (87% vs. 63%, p = 0.004), but no significant difference was found for carotid IMT (1.03 +/- 0.36 mm vs. 0.95 +/- 0.35 mm, p=NS). With the IDF definition, 61% of the patients had MS; this group was slightly older and included more women. There were no differences in terms of CAD (68% vs. 63%) or carotid IMT (0.97 +/- 0.34 vs. 0.96 +/- 0.39 mm). On multivariate analysis, the ATP III definition of MS predicts CAD (OR 4.76, 95% CI 1.71-13.25, p = 0.003), but the IDF definition does not (OR 1.29, 95% CI 0.74-2.27, p = 0.37). On ROC curve analysis, an IMT of > or = 0.95 mm predicts CAD (AUC 0.66, p < 0.001), with a sensitivity of 52% and specificity of 75%.
CONCLUSIONS: The new IDF definition increases the population with MS, decreasing the capacity to predict the presence of CAD. In our population, neither the ATP III nor the IDF definition showed differences in terms of carotid IMT. Carotid IMT can predict CAD, but with only modest sensitivity
Impact of Age on Treatment and Outcomes After Acute Myocardial Infarction, Particularly in Very Elderly Patients
INTRODUCTION: The elderly population admitted for acute myocardial infarction is increasing. This group is not well studied in international trials and is probably treated with a more conservative approach.
OBJECTIVES: To evaluate the presentation and treatment of myocardial infarction according to age, particularly in very elderly patients.
METHODS: We studied 1242 consecutive patients admitted with acute myocardial infarction, assessing in-hospital, 30-day and one-year mortality during follow-up for each age-group. Patients were divided into four groups according to age: <45 years (7.6%); 45-64 years (43.3%); 65-74 years (23.4%); and ≥75 years (25.7%).
RESULTS: Elderly patients had a worse risk profile (except for smoking), more previous history of coronary disease and a worse profile on admission, with the exception of lipid profile, which was more favorable. With regard to treatment of the elderly, although less optimized than in other age-groups, it was significantly better compared to other registries, including for percutaneous coronary angioplasty. Both complications and mortality were worse in the older groups. In elderly patients (≥75 years), adjusted risk of mortality was 4.9-6.3 times higher (p<0.001) than patients in the reference age-group (45-64 years). In these patients, the independent predictors of death were left ventricular function and renal function, use of beta-blockers being a predictor of survival.
CONCLUSIONS: Elderly patients represent a substantial proportion of the population admitted with myocardial infarction, and receive less evidenced-based therapy. Age is an independent predictor of short- and medium-term mortality
Power counting and renormalization group invariance in the subtracted kernel method for the two-nucleon system
We apply the subtracted kernel method (SKM), a renormalization approach based
on recursive multiple subtractions performed in the kernel of the scattering
equation, to the chiral nucleon-nucleon (NN) interactions up to
next-to-next-to-leading-order (NNLO). We evaluate the phase-shifts in the 1S0
channel at each order in Weinberg's power counting scheme and in a modified
power counting scheme which yields a systematic power-law improvement. We also
explicitly demonstrate that the SKM procedure is renormalization group
invariant under the change of the subtraction scale through a non-relativistic
Callan-Symanzik flow equation for the evolution of the renormalized NN
interactions.Comment: Accepted for publication in Journal of Physics G: Nuclear and
Particle Physic
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