573 research outputs found

    Finite size effects in perturbed boundary conformal field theories

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    We discuss the finite-size properties of a simple integrable quantum field theory in 1+1 dimensions with non-trivial boundary conditions. Novel off-critical identities between cylinder partition functions of models with differing boundary conditions are derived.Comment: 7 pages, 11 figures, JHEP proceedings style. Uses epsfig, amssymb. Talk given at the conference `Nonperturbative Quantum Effects 2000', Pari

    Complex WKB Analysis of a PT Symmetric Eigenvalue Problem

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    The spectra of a particular class of PT symmetric eigenvalue problems has previously been studied, and found to have an extremely rich structure. In this paper we present an explanation for these spectral properties in terms of quantisation conditions obtained from the complex WKB method. In particular, we consider the relation of the quantisation conditions to the reality and positivity properties of the eigenvalues. The methods are also used to examine further the pattern of eigenvalue degeneracies observed by Dorey et al. in [1,2].Comment: 22 pages, 13 figures. Added references, minor revision

    Differences Between Primary Care Physicians and Cardiologists in Management of Congestive Heart Failure: Relation to Practice Guidelines 11This work was supported in part by unrestricted grants from Bristol-Myers Squibb Co., Princeton, New Jersey; Burroughs Wellcome Co., Research Triangle Park, North Carolina; Merck & Co., West Point, Pennsylvania; and the Department of Veterans Affairs Research Service.22All editorial decisions for this article, including selection of referees, were made by a Guest Editor. This policy applies to all articles with authors from the University of California in San Francisco.

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    AbstractObjectives. This study was designed to characterize physician practices in the management of congestive heart failure (CHF) and to determine whether these practices vary by specialty and how they relate to guideline recommendations.Background. Congestive heart failure is responsible for considerable mortality, morbidity and health care resource utilization. Although there have been important advances in the diagnostic evaluation and treatment of CHF, little information is available on physician practices in this area.Methods. We surveyed physicians concerning their management of patients with CHF. The results were analyzed in multivariate models to determine the relation of diagnostic and treatment approaches to physician specialty, time since training, board certification and volume of patients with CHF. Surveys were sent to a sample of 2,250 family and general practitioners (FP/GPs), internists and cardiologists. Responses were examined in relation to guidelines issued by the Agency for Health Care Policy and Research that had been released 9 months previously.Results. Significant differences were found between physician groups with regard to each of the major guideline recommendations. For example, routine evaluation of left ventricular function, a point of emphasis in the guideline, is performed by 87% of cardiologists, but by only 77% of internists and 63% of FP/GPs (p < 0.001 between groups). Angiotensin-converting enzyme inhibitors were used by cardiologists, internists and FP/GPs in 80%, 71% and 60% of patients with mild to moderate CHF, respectively (p < 0.001 between groups). Larger differences were reported in the prescribed dosages of these drugs and their use in patients with renal dysfunction.Conclusions. Cardiologists report practices more in conformity with published guidelines for CHF than do internists and FP/GPs. Because of the large numbers of patients with CHF and their substantial mortality, morbidity and cost of care, these differences may have a major impact on outcomes and health care costs

    Preliminary data on volatile composition of olive fruits of cv. &quot;Simona&quot; and possible relationship to resistance to fly oviposition

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    By characterizing the volatile compounds of the olive cultivar \u201cSimona\u201d from southern Italy (Apulia region), we identified a way to analyze characteristics possibly linked to this olive\u2019s well-known resistance to fly oviposition. The pool of volatile compounds in the unripe and ripe fruits was identified, and even if the relative amounts of these compounds tended to vary with ripening, the fly repellent action appeared to be related to the sesquiterpenes such as alpha-copaene, cycloisosativene, alpha-muurolene, beta-cubebene and hydrocarbons such as (E)-2-dodecene, undecane, tridecane, and 3-methyl undecane. In agreement with the concept that the collective pool of volatile substances can enhance olfactory pleasure/repulsion more than would the effects of a single compound, the pool of volatile compounds identified in this paper may be among the possible characteristic mixtures with repellent action against Bactrocera oleae. The selection of volatile compounds made by the cuticle and responsible of the headspace quality surrounding the whole olive fruit is also demonstrated to be markedly different from the headspace volatile compounds produced by the extracted oil

    Determination of gamma-butyrolactone (GBL) in foods by SBSE-TD/GC/MS

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    4-hydroxybutyric acid lactone, or gamma-butyrolactone (GBL), is a molecule included in the FEMA (Flavor Extract Manufacturers Association) list of flavouring substances (No. 3291) and used as natural-identical substance in flavouring formulation. Recently, the use of GBL has been subjected to restrictions by FDA because, together with the conversion derivative GHB (gamma-hydroxybutyric acid), it has been recognized and classified as psychotropic. In 1999 the Italian law included GBL in the list of psychotropic substances and more recently in the Table of substances inducing psychic and physical addiction. However, GBL has been detected in several natural products. Under a toxicological point of view the difference between natural and natural-identical GBL in food is not relevant. In any case, the evaluation of the total content of GBL in many foods contributes to evaluate the consumption ratio and the aim of this paper is to evidence the possibility of detecting GBL with a high sensitivity method also in complex matrices with analytical procedure characterized by high recovery. This paper proposes a new, simplified, sensitive and selective method (SBSE-TD/GC/MS) useful to detect and quantify the GBL in foods. The work shows, as an application of this method, the detection of this molecule in the very complex matrix of a confectionery product on the international market. The reliability of the method was verified by recovery and repeatability tests. Recovery average values result between 85\u201392% (CV%=8.2\u20135.3) for the concentration range 1\u201310mg/l and between 92\u201395% (CV%=6.5\u20134.2) for the concentration range 10\u201325mg/l

    The dilute A_L models and the integrable perturbations of unitary minimal CFTs

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    Recently, a set of thermodynamic Bethe ansatz equations is proposed by Dorey, Pocklington and Tateo for unitary minimal models perturbed by \phi_{1,2} or \phi_{2,1} operator. We examine their results in view of the lattice analogues, dilute A_L models at regime 1 and 2. Taking M_{5,6}+\phi_{1,2} and M_{3,4}+\phi_{2,1} as the simplest examples, we will explicitly show that the conjectured TBA equations can be recovered from the lattice model in a scaling limit.Comment: 14 pages, 2 figure

    Determination of ethylene chlorhydrin as marker of spices fumigation with ethylene oxide

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    Ethylene oxide (EO) is a gas used to sterilize spices, drugs, packaging materials, medical devices, polyester fibers, plastics and synthetic rubber. When the aeration step foreseen for spices is not properly carried out, residues of EO and its deriv. ethylene chlorohydrin (ECH), produced by reaction with chlorine ions always present in the matrix, can be found in these products. In this way, the reactivity of EO with chlorides in spices provides a suitable marker to confirm the use of EO for fumigation. The ECH derived from spontaneous transformation during the storage and forcibly obtained during the first step of the extn. can be evaluated in spices by a simple GC/MS anal. method, without derivatization. It has been proven that the EO mol. is carcinogenic for humans; it has been classified as a category 1 carcinogen by the International Agency for Research on Cancer (IARC): ECH, as EO, is a mutagenic substance. This paper shows the results concerning 25 pepper samples purchased on the Italian market. The limit of detection for ECH was assumed to be 20 ?g/kg (LOD) and was calcd. by spiking a matrix pepper that had not been treated with EO. The limit of quantitation was assumed to be 100 ?g/kg (LOQ), i.e. 5 times LOD. The reliability of the method was verified by recovery and repeatability tests. Recovery av. values are 60-70% (CV% = 9.6-5.5) for the concn. range 100-500 ?g/kg. Only 56% of pepper samples analyzed did not contain ECH at detectable levels, and only 24% of pepper samples contained ECH at levels lower than LOQ. Three samples had a content ranging between 0.2 and 3.3 mg/kg and two samples showed a content of ECH higher than 5 mg/kg

    Determination of furan by headspace solid-phase microextraction\u2013 gas chromatography\u2013mass spectrometry in balsamic vinegars of Modena (Italy)

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    An isotope dilution method for quantification of furan by internal standardization was adopted, using head space solid phase microextraction (HS-SPME) technique, to evaluate various samples of \u2018\u2018aceto balsamico di Modena\u2019\u2019 (ABM), in order to verify if this seasoning may contribute to the intake of furans in the human diet. Matrix-matched calibration curves were adopted, and furan levels in the majority of the samples purchased on the Italian market ranged between 4 and 26 ng/g. Considering that furan levels in ABM derive from the heat-concentrated must of grapes and from the additive caramel E 150d often used in the production technology, the level of furan in the concentratedmust appears, in some samples, not to be the only important factor affecting the risk assessment of furan linked to the use of ABM
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