774 research outputs found

    The phase transitions in 2D Z(N) vector models for N>4

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    We investigate both analytically and numerically the renormalization group equations in 2D Z(N) vector models. The position of the critical points of the two phase transitions for N>4 is established and the critical index \nu\ is computed. For N=7, 17 the critical points are located by Monte Carlo simulations and some of the corresponding critical indices are determined. The behavior of the helicity modulus is studied for N=5, 7, 17. Using these and other available Monte Carlo data we discuss the scaling of the critical points with N and some other open theoretical problems.Comment: 19 pages, 8 figures, 10 tables; version to appear on Phys. Rev.

    Critical behavior of the compact 3d U(1) theory in the limit of zero spatial coupling

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    Critical properties of the compact three-dimensional U(1) lattice gauge theory are explored at finite temperatures on an asymmetric lattice. For vanishing value of the spatial gauge coupling one obtains an effective two-dimensional spin model which describes the interaction between Polyakov loops. We study numerically the effective spin model for N_t=1,4,8 on lattices with spatial extension ranging from L=64 to L=256. Our results indicate that the finite-temperature U(1) lattice gauge theory belongs to the universality class of the two-dimensional XY model, thus supporting the Svetitsky-Yaffe conjecture.Comment: 17 pages, 5 figures; two references added, a few comments included, title changed; version to appear on J. Stat. Mec

    Evaluation of the Efficacy and Safety of a Compound of Micronized Flavonoids in Combination With Vitamin C and Extracts of Centella asiatica, Vaccinium myrtillus, and Vitis vinifera for the Reduction of Hemorrhoidal Symptoms in Patients With Grade II and III Hemorrhoidal Disease: A Retrospective Real-Life Study

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    Background and Aim: Several evidences have shown how, in hemorrhoidal disease, phlebotonic flavonoid agents such as quercetin reduce capillary permeability by increasing vascular walls resistance, how rutin and vitamin C have antioxidant properties, and that Centella asiatica has reparative properties towards the connective tissue. A retrospective study was designed in order to evaluate the efficacy and safety of a compound consisting of micronized flavonoids in combination with vitamin C and extracts of C. asiatica, Vaccinium myrtillus, and Vitis vinifera for grade II and III hemorrhoidal disease. Patients and Methods: Data of 49 patients, over 18, who were following a free diet regimen, not on therapy with other anti-hemorrhoid agents, treated with a compound consisting of 450 mg of micronized diosmin, 300 mg of C. asiatica, 270 mg of micronized hesperidin, 200 mg of V. vinifera, 160 mg of vitamin C, 160 mg of V. myrtillus, 140 mg of micronized quercetin, and 130 mg of micronized rutin (1 sachet or 2 tablets a day) for 7 days were collected. Hemorrhoid grade according to Goligher’s scale together with anorectal symptoms (edema, prolapse, itching, thrombosis, burning, pain, tenesmus, and bleeding) both before treatment (T0) and after 7 days of therapy (T7) were collected. Primary outcomes were the reduction of at least one degree of hemorrhoids according to Goligher’s scale assessed by proctological examination and compound safety. The secondary outcome was the reduction of anorectal symptoms assessed by questionnaires administered to patients. Results: Forty-four patients (89.8%) presented a reduction in hemorrhoidal grade of at least one grade (p < 0.001). No adverse events with the use of the compound were noted. A significant reduction was observed in all anorectal symptoms evaluated (p < 0.05). No predictors of response to the compound were identified among the clinical and demographic variables collected. Conclusion: The compound analyzed was effective and safe for patients with grade II and III hemorrhoidal disease according to Goligher’s scale

    Critical behavior of the compact 3d U(1) gauge theory on isotropic lattices

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    We report on the computation of the critical point of the deconfinement phase transition, critical indices and the string tension in the compact three dimensional U(1) lattice gauge theory at finite temperatures. The critical indices govern the behavior across the deconfinement phase transition in the pure gauge U(1) model and are generally expected to coincide with the critical indices of the two-dimensional XY model. We studied numerically the U(1) model for N_t=8 on lattices with spatial extension ranging from L=32 to L=256. Our determination of the infinite volume critical point on the lattice with N_t=8 differs substantially from the pseudo-critical coupling at L=32, found earlier in the literature and implicitly assumed as the onset value of the deconfined phase. The critical index ν\nu computed from the scaling of the pseudo-critical couplings with the extension of the spatial lattice agrees well with the XY value ν\nu=1/2. On the other hand, the index η\eta shows large deviation from the expected universal value. The possible reasons of such behavior are discussed in details.Comment: 15 pages, 7 figures; version accepted for publication on J. Stat. Mech

    LONG-TERM TEMPERATURE MONITORING OF VOLCANIC AREAS BY DISTRIBUTED OPTICAL FIBER SENSORS

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    We present the first results of long- term monitoring of temperature profiles at the Campi Flegrei caldera. The measurements were carried out along a 76 meters-deep borehole already equipped with a borehole strain-meter. We installed a cable containing a loop of optical fiber in order to use a fiber-optics distributed sensor based on stimulated Brillouin scattering. The obtained data are consistent with results of both deep and surface geothermal explorations and indicate that geothermal gradient can be efficiently measured and monitored by the proposed technique

    Ghost-gluon coupling, power corrections and ΛMS\Lambda_{\overline {\rm MS}} from twisted-mass lattice QCD at Nf=2

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    We present results concerning the non-perturbative evaluation of the ghost-gluon running QCD coupling constant from Nf=2N_f=2 twisted-mass lattice calculations. A novel method for calibrating the lattice spacing, independent of the string tension and hadron spectrum is presented with results in agreement with previous estimates. The value of ΛMS\Lambda_{\overline{MS}} is computed from the running of the QCD coupling only after extrapolating to zero dynamical quark mass and after removing a non-perturbative OPE contribution that is assumed to be dominated by the dimension-two \VEV{A^2} gluon condensate. The effect due to the dynamical quark mass in the determination of \Lams is discussed.Comment: 33 pages, 6 fig

    Mecanismos de transferência de massa na desidratação osmótica de goiaba em soluções de sacarose, sucralose e açúcar invertido.

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    O objetivo deste trabalho foi avaliar o efeito da concentração de soluções de sacarose, sucralose e açúcar invertido sobre a cinética da desidratação osmótica de pedaços de goiaba. Frações de 1/12 do fruto foram imersas em soluções de sacarose a 0,5 e 0,4 g mL-1, de sacarose a 0,3 g mL-1 + sucralose a 0,2 g L-1 e em xarope de açúcar invertido, a 50 ºC, por 2 h, sob agitação de 60 min. A solução de açúcar invertido promoveu maior perda de água e redução de massa nas amostras de goiaba submetidas à desidratação osmótica. O melhor desempenho foi obtido para o tratamento em solução de sacarose a 0,4 g mL-1, com perda de água e redução de massa semelhantes aos valores obtidos na imersão em solução de sacarose a 0,5 g mL-1 e ganho de sólidos similar ao observado em solução de sacarose a 0,3 g mL-1

    Transthoracic echocardiography provides important long-term prognostic information in selected patients undergoing endovascular abdominal aortic repair

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    BACKGROUND: The value of performing transthoracic echocardiography (TTE) as part of the clinical assessment of patients awaiting endovascular repair of the abdominal aorta is little evaluated. We aimed to estimate the prognostic importance of information derived from TTE on long-term all-cause mortality in a selected group of patients undergoing endovascular aneurysm repair. METHODS AND RESULTS: This was a retrospective cohort study of 273 consecutive patients selected for endovascular aneurysm repair. All patients included in the analysis underwent TTE before their procedure. Multivariable Cox regression analysis was used to estimate the effect of TTE measures on all-cause mortality. Over a mean follow-up of 3.2±1.5 years, there were 78 deaths with a mean time to death of 1.28±1.16 years. A greater tubular ascending aorta (hazard ratio [HR] 5.6, 95% confidence interval [CI] 2.77-11.33), presence of mitral regurgitation (HR 8.13, 95% CI 4.09-12.16), lower left ventricular ejection fraction (HR 0.96, 95% CI 0.93-0.98), younger age (HR 0.97, 95% CI 0.95-0.99), and presence of diabetes mellitus (HR 1.46, 95% CI 1.24-1.89) were predictors of all-cause mortality. CONCLUSIONS: Echocardiography provides important long-term prognostic information in patients undergoing endovascular aneurysm repair. These TTE indices were more important at predicting outcome than standard conventional risk factors in this patient group. A greater tubular ascending aorta, presence of mitral regurgitation, reduced left ventricular ejection fraction, younger age, and diabetes mellitus were independently associated with long-term mortality

    Desidratação por imersão-impregnação e secagem por convecção de goiaba.

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    O objetivo deste trabalho foi avaliar as características físico-químicas e sensoriais de goiabas in natura e submetidas à desidratação por imersão-impregnação e à secagem complementar por convecção, além de avaliar a estabilidade da cor das goiabas secadas após 30, 60 e 90 dias de armazenamento sob refrigeração. Amostras de goiaba foram imersas em soluções de sacarose a 0,4 e 0,5 g mL-1, sacarose a 0,3 g mL-1 + sucralose a 0,2 g L-1, açúcar invertido a 41% (p/p) e açúcar invertido sem diluição. Foram avaliados sólidos solúveis totais, acidez titulável, pH, cor, aroma, aparência, sabor e textura. O teor de sólidos solúveis totais das amostras aumentou linearmente em função do tempo de imersão, sem efeito significativo do tipo de açúcar empregado no preparo da solução. A preservação do teor de ácido cítrico foi mais pronunciada em soluções menos concentradas de sacarose. Amostras secadas não submetidas à desidratação osmótica exibiram maior alteração de cor do que aquelas previamente desidratadas. Soluções de sacarose são mais eficazes na estabilidade da cor do que as de açúcar invertido. As goiabas submetidas à desidratação por imersão-impregnação tiveram boa aceitação sensorial, e aquelas secadas apenas por convecção não foram aceitas pelos provadores
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