347 research outputs found
Electromagnetic selection rules in the triangular alpha-cluster model of 12C
After recapitulating the procedure to find the bands and the states occurring
in the alpha-cluster model of C in which the clusters
are placed at the vertexes of an equilateral triangle, we obtain the selection
rules for electromagnetic transitions. While the alpha cluster structure leads
to the cancellation of E1 transitions, the approximations carried out in
deriving the roto-vibrational hamiltonian lead to the disappearance of M1
transitions. Furthermore, although in general the lowest active modes are E2,
E3, and M2, M3, , the cancellation of M2, M3 and M5
transitions between certain bands also occurs, as a result of the application
of group theoretical techniques drawn from molecular physics. These
implications can be very relevant for the spectroscopic analysis of
-ray spectra of C
P-Wave Two-Particle Bound and Scattering States in a Finite Volume including QED
The mass shifts for two-fermion bound and scattering P-wave states subject to
the long-range interactions due to QED in the non-relativistic regime are
derived. Introducing a short range force coupling the spinless fermions to one
unit of angular momentum in the framework of pionless EFT, we first calculate
both perturbatively and non-perturbatively the Coulomb corrections to
fermion-fermion scattering in the continuum and infinite volume context.
Motivated by the research on particle-antiparticle bound states, we extend the
results to fermions of identical mass and opposite charge. Second, we transpose
the system onto a cubic lattice with periodic boundary conditions and we
calculate the finite volume corrections to the energy of the lowest bound and
unbound eigenstates. In particular, power law corrections
proportional to the fine structure constant and resembling the recent results
for S-wave states are found. Higher order contributions in are
neglected, since the gapped nature of the momentum operator in the lattice
environnement allows for a perturbative treatment of the QED interactions.Comment: 73 pages, 7 figures, 0 tables. To be submitted to the European
Physical Journal
Pre-surgery urine metabolomics may predict late neurodevelopmental outcome in children with congenital heart disease
Background: From fetal life until cardiac surgery, complex congenital heart diseases (CHD) exhibit different hemodynamic and oxygenation patterns that can lead to alteration of the metabolic profile. We used a metabolomic approach to identify urine metabolic markers before cardiac surgery, aiming to define the physiology of patients with complex CHD and to contribute to predict their neurodevelopmental outcome. Methods: In a prospective, observational, single-center study we enrolled 28 patients with complex biventricular and univentricular CHD aged less than 5 years, on stable hemodynamic conditions, and with no genetic anomalies. We analyzed urine samples, collected at the induction of anesthesia, by 1H NMR spectroscopy. Profiles of 1H NMR spectra were submitted to unsupervised (principal component) and supervised (partial least squares-discriminant) multivariate analysis. Neurodevelopment was assessed by neuropsychological and adaptive functioning testing. Results: Principal components analysis divided CHD patients metabolic profiles in two distinct clusters (RED and BLACK). Metabolic profiles belonging to the RED cluster showed higher levels of accumulation of citric acid cycle intermediates and glucose compared to the profiles in the BLACK cluster, indicating a possible switching to anaerobic metabolism. Patients belonging to the RED cluster were significantly more prone to show an adverse neurodevelopment pattern (p = 0.01). Conclusions: The application of metabolomic analysis to CHD children permitted a deeper insight on their metabolic status that could help to obtain a better understanding of the physiological implications and to predict long-term neurodevelopmental outcome. © 201
Minimally Invasive Approach in Surgery for Congenital Heart Disease
Surgery for congenital heart disease (CHD) has changed considerably during the last decade. Improved surgical results in patients with simple CHD and new interventional cardiology procedures have stimulated the surgeon to adopt minimally invasive techniques to reduce the patient’s surgical insult and obtain good functional and cosmetic results. As a consequence, new surgical techniques and specialized equipment for minimally invasive cardiac surgery (MICS) procedures have been developed and refined in recent years. The improving surgical outcomes in patients with CHD, the significant advances in surgical instrumentation and perfusion technology, and the broad utilization of new catheter-based interventional procedures to repair simple CHD have triggered surgeons’ interest to adopt and innovate minimally invasive approaches for CHD repair, so as to reduce patient’s surgical trauma and improve functional and cosmetic results while maintaining a high standard of clinical outcomes and possibly shortening hospitalization times. This article reports on our updated full experience and institutional protocols with MICS in children and adults with CHD
Impact of migraine on fibromyalgia symptoms
Background: Fibromyalgia (FMS) and high frequency episodic/chronic migraine (M) very frequently co-occur, suggesting common pathophysiological mechanisms; both conditions display generalized somatic hyperalgesia. In FMS-M comorbidity we assessed if: a different level of hyperalgesia is present compared to one condition only; hyperalgesia is a function of migraine frequency; migraine attacks trigger FMS symptoms. Methods: Female patients with fibromyalgia (FMS)(n.40), high frequency episodic migraine (M1)(n.41), chronic migraine (M2)(n.40), FMS + M1 (n.42) and FMS + M2 (n.40) underwent recording of: −electrical pain thresholds in skin, subcutis and muscle and pressure pain thresholds in control sites, −pressure pain thresholds in tender points (TePs), −number of monthly migraine attacks and fibromyalgia flares (3-month diary). Migraine and FMS parameters were evaluated before and after migraine prophylaxis, or no prophylaxis, for 3 months with calcium-channel blockers, in two further FMS + H1 groups (n.49, n.39). 1-way ANOVA was applied to test trends among groups, Student’s t-test for paired samples was used to compare pre and post-treatment values. Results: The lowest electrical and pressure thresholds at all sites and tissues were found in FMS + M2, followed by FMS + H1, FMS, M2 and M1 (trend: p < 0.0001). FMS monthly flares were progressively higher in FMS, FMS + M1 and FMS + M2 (p < 0.0001); most flares (86–87 %) occurred within 12 h from a migraine attack in co-morbid patients (p < 0.0001). Effective migraine prophylaxis vs no prophylaxis also produced a significant improvement of FMS symptoms (decreased monthly flares, increased pain thresholds)(0.0001 < p < 0.003). Conclusions: Co-morbidity between fibromyalgia and migraine involves heightened somatic hyperalgesia compared to one condition only. Increased migraine frequency – with shift towards chronicity – enhances both hyperalgesia and spontaneous FMS pain, which is reversed by effective migraine prophylaxis. These results suggest different levels of central sensitization in patients with migraine, fibromyalgia or both conditions and a role for migraine as a triggering factor for FMS
A European study on decellularized homografts for pulmonary valve replacement: initial results from the prospective ESPOIR Trial and ESPOIR Registry data\u2020
OBJECTIVES: Decellularized pulmonary homografts (DPH) have shown excellent results for pulmonary valve replacement. However, controlled multicentre studies are lacking to date.METHODS: Prospective European multicentre trial evaluating DPH for pulmonary valve replacement. Matched comparison of DPH to bovine jugular vein (BJV) conduits and cryopreserved homografts (CH) considering patient age, type of heart defect and previous procedures.RESULTS: In total, 121 patients (59 female) were prospectively enrolled (August 2014-December 2016), age 21.3 +/- 14.4 years, DPH diameter 24.4 +/- 2.8 mm. No adverse events occurred with respect to surgical handling; there were 2 early deaths (30 + 59 years) due to myocardial failure after multi-valve procedures and no late mortality (1.7% mortality). After a mean follow-up of 2.2 +/- 0.6 years, the primary efficacy end points mean peak gradient (16.1 +/- 12.1 mmHg) and regurgitation (mean 0.25 +/- 0.48, grade 0-3) were excellent. One reoperation was required for recurrent subvalvular stenosis caused by a pericardial patch and 1 balloon dilatation was performed on a previously stented LPA. 100% follow-up for DPH patients operated before or outside the trial (n = 114) included in the ESPOIR Registry, age 16.6 +/- 10.4 years, diameter 24.1 +/- 4.2 mm, follow-up 5.1 +/- 3.0 years. The combined DPH cohort, n = 235, comprising both Trial and Registry data showed significantly better freedom from explantation (DPH 96.7 +/- 2.1%, CH 84.4 +/- 3.2%, P = 0.029 and BJV 82.7 +/- 3.2%, P = 0.012) and less structural valve degeneration at 10 years when matched to CH, n = 235 and BJV, n = 235 (DPH 61.4 +/- 6.6%, CH 39.9 +/- 4.4%, n.s., BJV 47.5 +/- 4.5%, P = 0.029).CONCLUSIONS: Initial results of the prospective multicentre ESPOIR Trial showed DPH to be safe and efficient. Current DPH results including Registry data were superior to BJV and CH.Thoracic Surger
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