A nonlocal, covariant generalisation of the NJL model

We solve a nonlocal generalisation of the NJL model in the Hartree approximation. This model has a separable interaction, as suggested by instanton models of the QCD vacuum. The choice of form factor in this interaction is motivated by the confining nature of the vacuum. A conserved axial current is constructed in the chiral limit of the model and the pion properties are shown to satisfy the Gell-Mann--Oakes--Renner relation. For reasonable values of the parameters the model exhibits quark confinement.Comment: 13 pages (RevTeX), MC/TH 94/1

Explicitly Covariant Light-Front Dynamics and Relativistic Few-Body Systems

The wave function of a composite system is defined in relativity on a space-time surface. In the explicitly covariant light-front dynamics, reviewed in the present article, the wave functions are defined on the plane \omega \cd x=0, where $\omega$ is an arbitrary four-vector with $\omega^2=0$. The standard non-covariant approach is recovered as a particular case for $\omega = (1,0,0,-1)$. Using the light-front plane is of crucial importance, while the explicit covariance gives strong advantages emphasized through all the review. The properties of the relativistic few-body wave functions are discussed in detail and are illustrated by examples in a solvable model. The three-dimensional graph technique for the calculation of amplitudes in the covariant light-front perturbation theory is presented. The structure of the electromagnetic amplitudes is studied. We investigate the ambiguities which arise in any approximate light-front calculations, and which lead to a non-physical dependence of the electromagnetic amplitude on the orientation of the light-front plane. The elastic and transition form factors free from these ambiguities are found for spin 0, 1/2 and 1 systems. The formalism is applied to the calculation of the relativistic wave functions of two-nucleon systems (deuteron, scattering state), with particular attention to the role of their new components in the deuteron elastic and electrodisintegration form factors and to their connection with meson exchange currents. Straigthforward applications to the pion and nucleon form factors and the $\rho-\pi$ transition are also made.Comment: latex.tar.gz file, 162 pages, 42 figures, to be published in Physics Reports (next issues

Bethe-Salpeter Approach for Unitarized Chiral Perturbation Theory

The Bethe-Salpeter equation restores exact elastic unitarity in the $s-$ channel by summing up an infinite set of chiral loops. We use this equation to show how a chiral expansion can be undertaken in the two particle irreducible amplitude and the propagators accomplishing exact elastic unitarity at any step. Renormalizability of the amplitudes can be achieved by allowing for an infinite set of counter-terms as it is the case in ordinary Chiral Perturbation Theory. Crossing constraints can be imposed on the parameters to a given order. Within this framework, we calculate the leading and next-to-leading contributions to the elastic $\pi \pi$ scattering amplitudes, for all isospin channels, and to the vector and scalar pion form factors in several renormalization schemes. A satisfactory description of amplitudes and form factors is obtained. In this latter case, Watson's theorem is automatically satisfied. From such studies we obtain a quite accurate determination of some of the ChPT $SU(2)-$low energy parameters ({\bar l}_1 - {\bar l}_2 = -6.1\er{0.1}{0.3} and ${\bar l}_6= 19.14 \pm 0.19$). We also compare the two loop piece of our amplitudes to recent two--loop calculations.Comment: 63 pages, 9 figures. Some discussions on off-shell ambiguities and convergence of the expansion adde

Systemic and topical antibiotics for chronic rhinosinusitis

BACKGROUND: This review is one of six looking at the primary medical management options for patients with chronic rhinosinusitis.Chronic rhinosinusitis is common and is characterised by inflammation of the lining of the nose and paranasal sinuses leading to nasal blockage, nasal discharge, facial pressure/pain and loss of sense of smell. The condition can occur with or without nasal polyps. Systemic and topical antibiotics are used with the aim of eliminating infection in the short term (and some to reduce inflammation in the long term), in order to normalise nasal mucus and improve symptoms. OBJECTIVES: To assess the effects of systemic and topical antibiotics in people with chronic rhinosinusitis. SEARCH METHODS: The Cochrane ENT Information Specialist searched the Cochrane ENT Trials Register; CENTRAL (2015, Issue 8); MEDLINE; EMBASE; ClinicalTrials.gov; ICTRP and additional sources for published and unpublished trials. The date of the search was 29 September 2015. SELECTION CRITERIA: Randomised controlled trials (RCTs) with a follow-up period of at least three months comparing systemic or topical antibiotic treatment to (a) placebo or (b) no treatment or (c) other pharmacological interventions. DATA COLLECTION AND ANALYSIS: We used the standard methodological procedures expected by Cochrane. Our primary outcomes were disease-specific health-related quality of life (HRQL), patient-reported disease severity and the commonest adverse event - gastrointestinal disturbance. Secondary outcomes included general HRQL, endoscopic nasal polyp score, computerised tomography (CT) scan score and the adverse events of suspected allergic reaction (rash or skin irritation) and anaphylaxis or other very serious reactions. We used GRADE to assess the quality of the evidence for each outcome; this is indicated in italics. MAIN RESULTS: We included five RCTs (293 participants), all of which compared systemic antibiotics with placebo or another pharmacological intervention.The varying study characteristics made comparison difficult. Four studies recruited only adults and one only children. Three used macrolide, one tetracycline and one a cephalosporin-type antibiotic. Three recruited only patients with chronic rhinosinusitis without nasal polyps, one recruited patients with chronic rhinosinusitis with nasal polyps and one had a mixed population. Three followed up patients for 10 to 12 weeks after treatment had finished. Systemic antibiotics versus placeboThree studies compared antibiotics with placebo (176 participants).One study (64 participants, without polyps) reported disease-specific HRQL using the SNOT-20 (0 to 5, 0 = best quality of life). At the end of treatment (three months) the SNOT-20 score was lower in the group receiving macrolide antibiotics than the placebo group (mean difference (MD) -0.54 points, 95% confidence interval (CI) -0.98 to -0.10), corresponding to a moderate effect size favouring antibiotics (moderate quality evidence). Three months after treatment, it is uncertain if there was a difference between groups.One study (33 participants, with polyps) provided information on gastrointestinal disturbances and suspected allergic reaction (rash or skin irritation) after a short course of tetracycline antibiotic compared with placebo. We are very uncertain if antibiotics were associated with an increase in gastrointestinal disturbances (risk ratio (RR) 1.36, 95% CI 0.22 to 8.50) or skin irritation (RR 6.67, 95% CI 0.34 to 128.86) (very low quality evidence). Systemic antibiotics plus saline irrigation and intranasal corticosteroids versus placebo plus saline irrigation and intranasal corticosteroidsOne study (60 participants, some with and some without polyps) compared a three-month course of macrolide antibiotic with placebo; all participants also used saline irrigation and 70% used intranasal corticosteroids. Disease-specific HRQL was reported using SNOT-22 (0 to 110, 0 = best quality of life). Data were difficult to interpret (highly skewed and baseline imbalances) and it is unclear if there was an important difference at any time point (low quality evidence). To assess patient-reported disease severity participants rated the effect of treatment on a five-point scale (-2 for "desperately worse" to 2 for "cured") at the end of treatment (three months). For improvement in symptoms there was no difference between the antibiotics and placebo groups; the RR was 1.50 (95% CI 0.81 to 2.79; very low quality evidence), although there were also slightly more people who felt worse after treatment in the antibiotics group. There was no demonstrable difference in the rate of gastrointestinal disturbances between the groups (RR 1.07, 95% CI 0.16 to 7.10). General HRQL was measured using the SF-36. The authors stated that there was no difference between groups at the end of treatment (12 weeks) or two weeks later. Systemic antibiotics versus intranasal corticosteroidsOne study (43 participants, without polyps) compared a three-month course of macrolide antibiotic with intranasal corticosteroids. Patient-reported disease severity was assessed using a composite symptom score (0 to 40; 0 = no symptoms). It is very uncertain if there was a difference as patient-reported disease severity was similar between groups (MD -0.32, 95% CI -2.11 to 1.47; low quality evidence). Systemic antibiotics versus oral corticosteroidsOne study (28 participants, with polyps) compared a short course of tetracycline antibiotic (unclear duration, ˜20 days) with a 20-day course of oral corticosteroids. We were unable to extract data on any of the primary efficacy outcomes. It is uncertain if there was a difference ingastrointestinal disturbances (RR 1.00, 95% CI 0.16 to 6.14) or skin irritation (RR 2.00, 95% CI 0.20 to 19.62) as the results for these outcomes were similar between groups (very low quality evidence). AUTHORS' CONCLUSIONS: We found very little evidence that systemic antibiotics are effective in patients with chronic rhinosinusitis. We did find moderate quality evidence of a modest improvement in disease-specific quality of life in adults with chronic rhinosinusitis without polyps receiving three months of a macrolide antibiotic. The size of improvement was moderate (0.5 points on a five-point scale) and only seen at the end of the three-month treatment; by three months later no difference was found.Despite a general understanding that antibiotics can be associated with adverse effects, including gastrointestinal disturbances, the results in this review were very uncertain because the studies were small and few events were reported.No RCTs of topical antibiotics met the inclusion criteria.More research in this area, particularly evaluating longer-term outcomes and adverse effects, is required

Nonperturbative Light-Front QCD

In this work the determination of low-energy bound states in Quantum Chromodynamics is recast so that it is linked to a weak-coupling problem. This allows one to approach the solution with the same techniques which solve Quantum Electrodynamics: namely, a combination of weak-coupling diagrams and many-body quantum mechanics. The key to eliminating necessarily nonperturbative effects is the use of a bare Hamiltonian in which quarks and gluons have nonzero constituent masses rather than the zero masses of the current picture. The use of constituent masses cuts off the growth of the running coupling constant and makes it possible that the running coupling never leaves the perturbative domain. For stabilization purposes an artificial potential is added to the Hamiltonian, but with a coefficient that vanishes at the physical value of the coupling constant. The weak-coupling approach potentially reconciles the simplicity of the Constituent Quark Model with the complexities of Quantum Chromodynamics. The penalty for achieving this perturbative picture is the necessity of formulating the dynamics of QCD in light-front coordinates and of dealing with the complexities of renormalization which such a formulation entails. We describe the renormalization process first using a qualitative phase space cell analysis, and we then set up a precise similarity renormalization scheme with cutoffs on constituent momenta and exhibit calculations to second order. We outline further computations that remain to be carried out. There is an initial nonperturbative but nonrelativistic calculation of the hadronic masses that determines the artificial potential, with binding energies required to be fourth order in the coupling as in QED. Next there is a calculation of the leading radiative corrections to these masses, which requires our renormalization program. Then the real struggle of finding the right extensions to perturbation theory to study the strong-coupling behavior of bound states can begin.Comment: 56 pages (REVTEX), Report OSU-NT-94-28. (figures not included, available via anaonymous ftp from pacific.mps.ohio-state.edu in subdirectory pub/infolight/qcd

Electromagnetic and weak current operators for interacting systems within the front-form dynamics

Electromagnetic and weak current operators for interacting systems should properly commute with the Poincar\'e generators and satisfy Hermiticity. The electromagnetic current should also satisfy ${\cal P}$ and ${\cal T}$ covariance and continuity equation. We show that in front-form dynamics the current can be constructed from auxiliary operators, defined in a Breit frame where initial and final three-momenta of the system are directed along the $z$ axis. Poincar\'e covariance constraints reduce for auxiliary operators to the ones imposed only by kinematical rotations around the $z$ axis; while Hermiticity requires a suitable behaviour of the auxiliary operators under rotations by $\pi$ around the $x$ or $y$ axes. Applications to deep inelastic structure functions and electromagnetic form factors are discussed. Elastic and transition form factors can be extracted without any ambiguity and in the elastic case the continuity equation is automatically satisfied, once Poincar\'e, ${\cal P}$ and ${\cal T}$ covariance, together with Hermiticity, are imposed.Comment: 40 pages, submitted to Nucl. Phys.

Sleep study, respiratory mechanics, chemosensitive response and quality of life in morbidly obese patients undergoing bariatric surgery: a prospective, randomized, controlled trial

<p>Abstract</p> <p>Background</p> <p>Obesity is a major public health problem in both developed and developing countries alike and leads to a series of changes in respiratory physiology. There is a strong correlation between obesity and cardiopulmonary sleep disorders. Weight loss among such patients leads to a reduction in these alterations in respiratory physiology, but clinical treatment is not effective for a long period of time. Thus, bariatric surgery is a viable option.</p> <p>Methods/Design</p> <p>The present study involves patients with morbid obesity (BMI of 40 kg/m²or 35 kg/m²to 39.9 kg/m²with comorbidities), candidates for bariatric surgery, screened at the Santa Casa de Misericórdia Hospital in the city of Sao Paulo (Brazil). The inclusion criteria are grade III morbid obesity, an indication for bariatric surgery, agreement to participate in the study and a signed term of informed consent. The exclusion criteria are BMI above 55 kg/m², clinically significant or unstable mental health concerns, an unrealistic postoperative target weight and/or unrealistic expectations of surgical treatment. Bariatric surgery candidates who meet the inclusion criteria will be referred to Santa Casa de Misericórdia Hospital and will be reviewed again 30, 90 and 360 days following surgery. Data collection will involve patient records, personal data collection, objective assessment of HR, BP, neck circumference, chest and abdomen, collection and analysis of clinical preoperative findings, polysomnography, pulmonary function test and a questionnaire on sleepiness.</p> <p>Discussion</p> <p>This paper describes a randomised controlled trial of morbidly obese patients. Polysomnography, respiratory mechanics, chemosensitive response and quality of life will be assessed in patients undergoing or not undergoing bariatric surgery.</p> <p>Trial Registration</p> <p>The protocol for this study is registered with the Brazilian Registry of Clinical Trials - ReBEC (RBR-9k9hhv).</p

Light Front Quantization--A Technique for Relativistic and Realistic Nuclear Physics

Applications of relativistic light front dynamics to computing wave functions of heavy nuclei are reviewed. The motivation for this is the desire to find wave functions, expressed in terms of the plus-momentum variable, that simplify the analyses of high energy experiments such as deep inelastic scattering, Drell-Yan production, (e,e') and (p,p').Some examples of ordinary quantum mechanics are solved to show that the formalism is tractable. Light-front quantization is reviewed briefly and applied to: infinite nuclear matter within the mean field approximation; a simple static source theory; finite nuclei using the mean field approximation; low-energy pion-nucleon scattering using a chiral Lagrangian; nucleon-nucleon scattering, within the one boson exchange approximation; and, infinite nuclear matter including the effects of two-nucleon correlations. Standard good results for nuclear saturation properties are obtained, with a possible improvement in the computed nuclear compressibility. Manifest rotational invariance is not used as an aid in doing calculations, but it does emerge in the results. It seems that nuclear physics can be done in a manner in which modern nuclear dynamics is respected, boost invariance in the $z$-direction is preserved, and in which rotational invariance is maintained. A salient feature is that $\omega,\sigma$ and $\pi$ mesons are important constituents of nuclei. It seems possible to find Lagrangians that yield reasonable descriptions of nuclear deep inelastic scattering and Drell-Yan reactions. Furthermore, the presence of the $\sigma$ and $\omega$ mesons could provide a nuclear enhancement of the ratio of the cross sections for longitudinally and transversely polarized virtual photons in accord with recent measurements by the HERMES collaboration.Comment: Prepared for Prog. Nucl. Part. Phys. 45 (2000

Light Front Treatment of Nuclei: Formalism and Simple Applications

A relativistic light front treatment of nuclei is developed by performing light front quantization for a chiral Lagrangian. The energy momentum tensor and the appropriate Hamiltonian are obtained. Three illustrations of the formalism are made. (1) Pion-nucleon scattering at tree level is shown to reproduce soft pion theorems. (2) The one boson exchange treatment of nucleon-nucleon scattering is developed and shown (by comparison with previous results of the equal time formulation) to lead to a reasonable description of nucleon-nucleon phase shifts. (3) The mean field approximation is applied to infinite nuclear matter, and the plus momentum distributions of that system are studied. The mesons are found to carry a significant fraction of the plus momentum, but are inaccessible to experiments.Comment: 48 pages, ReVTex, 3 .eps files included, submitted to Phys. Rev.

International Consensus Statement on Rhinology and Allergy: Rhinosinusitis

Background: The 5 years since the publication of the first International Consensus Statement on Allergy and Rhinology: Rhinosinusitis (ICAR‐RS) has witnessed foundational progress in our understanding and treatment of rhinologic disease. These advances are reflected within the more than 40 new topics covered within the ICAR‐RS‐2021 as well as updates to the original 140 topics. This executive summary consolidates the evidence‐based findings of the document. Methods: ICAR‐RS presents over 180 topics in the forms of evidence‐based reviews with recommendations (EBRRs), evidence‐based reviews, and literature reviews. The highest grade structured recommendations of the EBRR sections are summarized in this executive summary. Results: ICAR‐RS‐2021 covers 22 topics regarding the medical management of RS, which are grade A/B and are presented in the executive summary. Additionally, 4 topics regarding the surgical management of RS are grade A/B and are presented in the executive summary. Finally, a comprehensive evidence‐based management algorithm is provided. Conclusion: This ICAR‐RS‐2021 executive summary provides a compilation of the evidence‐based recommendations for medical and surgical treatment of the most common forms of RS