The Index Theorem and Universality Properties of the Low-lying Eigenvalues of Improved Staggered Quarks

We study various improved staggered quark Dirac operators on quenched gluon backgrounds in lattice QCD generated using a Symanzik-improved gluon action. We find a clear separation of the spectrum into would-be zero modes and others. The number of would-be zero modes depends on the topological charge as expected from the Index Theorem, and their chirality expectation value is large (approximately 0.7). The remaining modes have low chirality and show clear signs of clustering into quartets and approaching the random matrix theory predictions for all topological charge sectors. We conclude that improvement of the fermionic and gauge actions moves the staggered quarks closer to the continuum limit where they respond correctly to QCD topology.Comment: 4 pages, 3 figure

Probing the chiral weak Hamiltonian at finite volumes

Non-leptonic kaon decays are often described through an effective chiral weak Hamiltonian, whose couplings ("low-energy constants") encode all non-perturbative QCD physics. It has recently been suggested that these low-energy constants could be determined at finite volumes by matching the non-perturbatively measured three-point correlation functions between the weak Hamiltonian and two left-handed flavour currents, to analytic predictions following from chiral perturbation theory. Here we complete the analytic side in two respects: by inspecting how small ("epsilon-regime") and intermediate or large ("p-regime") quark masses connect to each other, and by including in the discussion the two leading Delta I = 1/2 operators. We show that the epsilon-regime offers a straightforward strategy for disentangling the coefficients of the Delta I = 1/2 operators, and that in the p-regime finite-volume effects are significant in these observables once the pseudoscalar mass M and the box length L are in the regime ML \lsim 5.0.Comment: 37 pages. v2: some additions and clarifications; published versio

Coherent Control of Isotope Separation in HD+ Photodissociation by Strong Fields

The photodissociation of the HD+ molecular ion in intense short- pulsed linearly polarized laser fields is studied using a time- dependent wave-packet approach where molecular rotation is fully included. We show that applying a coherent superposition of the fundamental radiation with its second harmonic can lead to asymmetries in the fragment angular distributions, with significant differences between the hydrogen and deuterium distributions in the long wavelength domain where the permanent dipole is most efficient. This effect is used to induce an appreciable isotope separation.Comment: Physical Review Letters, 1995 (in press). 4 pages in revtex format, 3 uuencoded figures. Full postcript version available at: http://chemphys.weizmann.ac.il/~charron/prl.ps or ftp://scipion.ppm.u-psud.fr/coherent.control/prl.p

Laparoscopic gastric banding

Introduction: Laparoscopic gastric banding (LGB) is currently the most popular purely restrictive bariatric operation in Europe and many other countries. It has a low operative morbidity, but is associated with a substantial late complication rate. Many late complications have been attributed to technical errors or to the learning curve. The aim of this paper is to present our results with gastric banding after the learning curve in order to disclose the true incidence of long-term complications. Methods: LGB was introduced in our department in December 1995. Thirty patients were operated on until June 1997 using the early banding technique (band within the lesser sac), at which time the surgical technique was slightly modified in order to place the band above the lesser sac. Then another 300 patients underwent LGB using either the Lapband or the SAGB system. This report focuses on the latter patients. All the data were collected prospectively. Results: The series includes 300 patients (257 women and 43 men) with a mean age of 38.3 years (19-64). The mean initial weight was 119.2 kg (57-179), initial body mass index (BMI) was 43.3 kg/m2 (21-64), and initial excess weight was 96.5% (0-191). The mean duration of surgery was 90 min, decreasing over time to a mean of 75 min for the last 50 cases. Early overall morbidity was 6.6%. Major complications occurred in 7 patients (2.3%). Excess weight loss (EWL) was at least 50% in 66% of the patients after 2 years, averaging 60%, with no substantial change until 4 years, and the BMI stabilized between 30 and 31 kg/m2. Forty-nine patients developed a total of 52 long-term complications, of which 23 (7.6%) were related only to the port or catheter. Band erosion occurred in 17 (5.6%), pouch dilatation with slippage in 8 (2.6%), and infection in 4 (1.3%) patients. Fifty-five reoperations were necessary. Twenty-five of these were related only to the port. The band was removed from 26 (9%) patients, of whom 17 were converted to Roux-en-Y gastric bypass. Conclusions: LGB gives satisfactory results in terms of weight loss in about two-thirds of the patients. Even beyond the learning curve, the long-term morbidity is not negligible, but is acceptable compared to other procedures such as vertical banded gastroplasty. Conversion to gastric bypass is possible when complications occur and can be performed when the band is removed in most case

Two-nucleon emission in the longitudinal response

The contribution of the two-nucleon emission in the longitudinal response for inclusive electron scattering reactions is studied. The model adopted to perform the calculations is based upon Correlated Basis Function theory but it considers only first order terms in the correlation function. The proper normalization of the wave function is ensured by considering, in addition to the usually evaluated two-point diagrams, also the three-point diagrams. Results for the 12C nucleus in the quasi-elastic region are presented.Comment: 7 pages, 4 Postscript figure

Matrix models and QCD with chemical potential

The Random Matrix Model approach to Quantum Chromodynamics (QCD) with non-vanishing chemical potential is reviewed. The general concept using global symmetries is introduced, as well as its relation to field theory, the so-called epsilon regime of chiral Perturbation Theory (echPT). Two types of Matrix Model results are distinguished: phenomenological applications leading to phase diagrams, and an exact limit of the QCD Dirac operator spectrum matching with echPT. All known analytic results for the spectrum of complex and symplectic Matrix Models with chemical potential are summarised for the symmetry classes of ordinary and adjoint QCD, respectively. These include correlation functions of Dirac operator eigenvalues in the complex plane for real chemical potential, and in the real plane for imaginary isospin chemical potential. Comparisons of these predictions to recent Lattice simulations are also discussed

Human exposure to antibiotic resistant-Escherichia coli through irrigated lettuce

Antibiotic resistant bacteria (ARB) have been found on fresh fruit and vegetables globally. These types of ARB infections are spreading rapidly and are a major human health threat. A quantitative human exposure assessment model was created using scenario analysis to investigate the potential human exposure to antibiotic resistant Escherichia coli (AR-E. coli) through the consumption of lettuce irrigated with surface water. Scientific literature and site specific data were collected to model each process from farm to fork to calculate the concentration of AR-E. coli on the lettuce at the point of human consumption. The processes examined were the adhesion, colonisation and viability of bacteria on the lettuce; the effect of different post-harvest cleaning processes; the effect of consuming the lettuce before, on or after the expiry date; and the effect of the consumer washing the lettuce. The results show the mean human exposure levels ranged between 1.00 × 10−2 and 1.35 × 106 colony forming units (CFU) of AR-E. coli per 100 g of surface water irrigated lettuce for the different scenarios investigated. The mean probability of illness from consuming 100 g of lettuce contaminated with potential pathogenic antibiotic-sensitive E. coli was between 1.46 × 10−9 to 1.88 × 10−2. A back calculation revealed that in order for the EC No 1441/2007 regulation to be exceeded (≥1000 CFU/g of E. coli on lettuce at the manufacturing stage), the mean contamination levels required in the irrigation water would need to be 2.7, 3.1 or 4.8 log CFU/ml using the post-harvest treatments of washing with water, rapid cooling with water and washing with a chlorine solution respectively. The information generated from this model could help to set guidelines for producers on maximum permissible AR-E. coli contamination levels in irrigation water and provides recommendations on the best post-harvest treatment to use. Keywords: Antibiotic resistance, Escherichia coli, Irrigation, Human exposure, Lettuc

Evidence and Open Questions for the Use of Video-Feedback Interventions With Parents of Children With Neurodevelopmental Disabilities

The Video-Feedback Intervention (VFI) is a technique aimed at promoting positive parenting that has been found to be supportive of child development and parent–child interaction in different at-risk and clinical populations. The application of VFI with parents of children with neurodevelopmental disabilities (ND; e.g., cerebral palsy, sensory and/or psychomotor delay, and genetic syndromes) is growing. Nonetheless, no systematic review is currently available documenting whether this type of intervention improves children’s developmental outcomes (e.g., behavioral stability and cognitive abilities), parental caregiving skills (e.g., responsive parenting), and parental emotional well-being (e.g., depressive symptomatology). In the present mini-review, 212 VFI records were retrieved from three databases (i.e., PubMed, Scopus, and Web of Science), and 10 papers were finally included. Abstracted information included age, diagnosis, methodological aspects (timing, setting, and themes), and child/parent outcomes. Significant improvements from pre- to post-VFI were observed in all studies. Specifically, the VFIs were significantly associated with better children developmental outcomes and parental caregiving skills. Inconsistent findings emerged for the VFI effects on parental emotional well-being. Overall, the current mini-review supports the potential effectiveness of parent-focused VFI interventions for parents of children with ND, despite the presence of open questions that need to be addressed in future clinical trials