671 research outputs found

    The boundary supersymmetric sine-Gordon model revisited

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    We argue that, contrary to previous claims, the supersymmetric sine-Gordon model with boundary has a two-parameter family of boundary interactions which preserves both integrability and supersymmetry. We also propose the corresponding boundary S matrix for the first supermultiplet of breathers.Comment: 9 pages, LaTeX; amssymb, no figures; v2: one equation and one reference added; v3: more references and a "note added

    Liouville field theory coupled to a critical Ising model: Non-perturbative analysis, duality and applications

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    Two different kinds of interactions between a Zn{Z}_{n}-parafermionic and a Liouville field theory are considered. For generic values of nn, the effective central charges describing the UV behavior of both models are calculated in the Neveu-Schwarz sector. For n=2n=2 exact vacuum expectation values of primary fields of the Liouville field theory, as well as the first descendent fields are proposed. For n=1n=1, known results for Sinh-Gordon and Bullough-Dodd models are recovered whereas for n=2n=2, exact results for these two integrable coupled Ising-Liouville models are shown to exchange under a weak-strong coupling duality relation. In particular, exact relations between the parameters in the actions and the mass of the particles are obtained. At specific imaginary values of the coupling and n=2n=2, we use previous results to obtain exact information about: (a) Integrable coupled models like Ising-Mp/p{\cal M}_{p/p'}, homogeneous sine-Gordon model SU(3)2SU(3)_2 or the Ising-XY model; (b) Neveu-Schwarz sector of the Φ13\Phi_{13} integrable perturbation of N=1 supersymmetric minimal models. Several non-perturbative checks are done, which support the exact results.Comment: 29 pages, 1 fig., LaTeX file with epsfig, amssymb, 3 references added. To appear in Nucl. Phys.

    Classical behavior of deformed sine-Gordon models

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    In this work we deform the phi^4 model with distinct deformation functions, to propose a diversity of sine-Gordon-like models. We investigate the proposed models and we obtain all the topological solutions they engender. In particular, we introduce non-polynomial potentials which support some exotic two-kink solutions.Comment: 12 pages, 12 figures; version to appear in Physica

    Transcutaneous electrical nerve stimulation for acute pain: A review

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    Background: This is a second update of a Cochrane Review originally published in Issue 2, 2009. Transcutaneous Electrical Nerve Stimulation (TENS) is a non-pharmacological agent, based on delivering low voltage electrical currents to the skin. TENS is used by people to treat a variety of pain conditions. Objectives: To assess the analgesic effectiveness of TENS, as a sole treatment, for acute pain in adults. Search methods: We searched the following databases up to 3 December 2014: the Cochrane Central Register of Controlled Trials (CENTRAL), in the Cochrane Library; MEDLINE; EMBASE; CINAHL; and AMED. We also checked the reference lists of included trials. Selection criteria: We included randomised controlled trials (RCTs) of adults with acute pain (< 12 weeks) if they examined TENS given as a sole treatment and assessed pain with subjective pain scales. Trials were eligible if they compared TENS to placebo TENS, no treatment controls, pharmacological interventions or non-pharmacological interventions. We excluded trials on experimental pain, case reports, clinical observations, letters, abstracts or reviews. Also we excluded trials investigating the effect of TENS on pain during childbirth (labour), primary dysmenorrhoea or dental procedures. Studies where TENS was given with another treatment as part of the formal trial design were excluded. We did not restrict any articles based on language of publication. Data collection and analysis Two review authors independently assessed study eligibility and carried out study selection, data extraction, 'Risk of bias' assessment and analyses of data. We extracted data on the following: types of participants and pain condition, trial design and methods, treatment parameters, adverse effects, and outcome measures. We contacted trial authors for additional information if necessary. Main results: We included 12 trials in the original review (2009) and included no further trials in the first update (2011). An additional seven new trials met the inclusion criteria in this second update. In total, we included 19 RCTs involving 1346 participants at entry, with 11 trials awaiting classification either because the full text was unavailable or information in the full text failed to clarify eligibility. We excluded most trials because TENS was given in combination with another treatment as part of the formal study design or TENS was not delivered using appropriate TENS technique. The types of acute pain included in this Cochrane Review were procedural pain, e.g. cervical laser treatment, venepuncture, screening flexible sigmoidoscopy and non-procedural pain, e.g. postpartum uterine contractions and rib fractures. We pooled data for pain intensity for six trials (seven comparisons) comparing TENS with placebo but the I2 statistic suggested substantial heterogeneity. Mean difference (MD) with 95% confidence intervals (CIs) on a visual analogue scale (VAS, 100 mm) was -24.62 mm (95% CI -31.79 to -17.46) in favour of TENS. Data for the proportion of participants achieving ≥ 50% reduction in pain was pooled for four trials (seven comparisons) and relative risk was 3.91 (95% CI 2.42 to 6.32) in favour of TENS over placebo. We pooled data for pain intensity from five trials (seven comparisons) but the I2 statistic suggested considerable heterogeneity. MD was -19.05 mm (95% CI -27.30 to -10.79) in favour of TENS using a random-effects model. It was not possible to pool other data. There was a high risk of bias associated with inadequate sample sizes in treatment arms and unsuccessful blinding of treatment interventions. Seven trials reported minor adverse effects, such as mild erythema and itching underneath the electrodes and participants disliking TENS sensation. Authors' conclusions: This Cochrane Review update includes seven new trials, in addition to the 12 trials reviewed in the first update in 2011. The analysis provides tentative evidence that TENS reduces pain intensity over and above that seen with placebo (no current) TENS when administered as a stand-alone treatment for acute pain in adults. The high risk of bias associated with inadequate sample sizes in treatment arms and unsuccessful blinding of treatment interventions makes definitive conclusions impossible. There was incomplete reporting of treatment in many reports making replication of trials impossible

    The use of polymers in the treatment of retinal detachment: current trends and future perspectives

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    Procedures for the treatment of retinal detachment and related conditions have been successfully improved upon in recent years thanks to the advent of new therapies and biomaterials. This review, after giving an overview on eye structure and function, focuses on the treatment of retinal detachment and examines the role and features of the materials used in vitreoretinal surgery, emphasizing scleral buckling and short-term/long-term vitreous tamponade. Specifically, the limitations of existing biomaterials are underlined, based on experimental studies and with particular reference to cells/material interactions. Finally, current and future trends of biomaterials’ research in the field of vitreoretinal surgery are considered and discussed

    Safety of intravenous ferric carboxymaltose versus oral iron in patients with nondialysis-dependent CKD: an analysis of the 1-year FIND-CKD trial.

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    Background: The evidence base regarding the safety of intravenous (IV) iron therapy in patients with chronic kidney disease (CKD) is incomplete and largely based on small studies of relatively short duration. Methods: FIND-CKD (ClinicalTrials.gov number NCT00994318) was a 1-year, open-label, multicenter, prospective study of patients with nondialysis-dependent CKD, anemia and iron deficiency randomized (1:1:2) to IV ferric carboxymaltose (FCM), targeting higher (400-600 µg/L) or lower (100-200 µg/L) ferritin, or oral iron. A post hoc analysis of adverse event rates per 100 patient-years was performed to assess the safety of FCM versus oral iron over an extended period. Results: The safety population included 616 patients. The incidence of one or more adverse events was 91.0, 100.0 and 105.0 per 100 patient-years in the high ferritin FCM, low ferritin FCM and oral iron groups, respectively. The incidence of adverse events with a suspected relation to study drug was 15.9, 17.8 and 36.7 per 100 patient-years in the three groups; for serious adverse events, the incidence was 28.2, 27.9 and 24.3 per 100 patient-years. The incidence of cardiac disorders and infections was similar between groups. At least one ferritin level ≥800 µg/L occurred in 26.6% of high ferritin FCM patients, with no associated increase in adverse events. No patient with ferritin ≥800 µg/L discontinued the study drug due to adverse events. Estimated glomerular filtration rate remained the stable in all groups. Conclusions: These results further support the conclusion that correction of iron deficiency anemia with IV FCM is safe in patients with nondialysis-dependent CKD

    MODELLING OF COLLECTIVE MOVEMENT IN IMMERSIVE ENVIRONMENTS

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    Immersive technologies allow us to map physical reality by means of 4D virtual systems in ever higher spatial and temporal detail, up to a scale level of 1&thinsp;:&thinsp;1. This level of detail enables the representation of phenomena that have been widely ignored by the geovisualization research agenda as yet. An example for such a large scale phenomenon is the collective movement of animals, which can be modelled and visualized only at a fine grained spatio-temporal resolution. This paper focuses on how collective movement can be modelled in an immersive virtual reality (VR) geovisualization. In a brief introduction on immersion and spatial presence we will argue, that high fidelity and realistic VR can strengthen the users’ involvement with the issues visualized. We will then discuss basic characteristics of swarming in nature and review the principal models that have been presented to formalize this collective behavior. Based on the rules of (1) collision avoidance, (2) polarization, (3) aggregation and (4) self-organized criticality we will formulate a viable solution of modelling collective movement within a geovisualization immersive virtual environment. An example of use and results will be presented

    On the Scalar Potential Models from the Isospectral Potential Class

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    Static field classical configurations in (1+1)-dimensions for new non-linear potential models are investigated from an isospectral potential class and the concept of bosonic zero- mode solution. One of the models here considered has a static non-topological configuration with a single vacuum state that breaks supersymmetry.Comment: Revtex, 14 pages, 4 figures. To appear in the Phys. Lett. A ( Accepted in 04.04.2002
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