265 research outputs found

    Gauge and Poincare' Invariant Regularization and Hopf Symmetries

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    We consider the regularization of a gauge quantum field theory following a modification of the Polchinski proof based on the introduction of a cutoff function. We work with a Poincare' invariant deformation of the ordinary point-wise product of fields introduced by Ardalan, Arfaei, Ghasemkhani and Sadooghi, and show that it yields, through a limiting procedure of the cutoff functions, to a regularized theory, preserving all symmetries at every stage. The new gauge symmetry yields a new Hopf algebra with deformed co-structures, which is inequivalent to the standard one.Comment: Revised version. 14 pages. Incorrect statements eliminate

    A Validated Reversed-Phase HPLC Method for the Determination of Atorvastatin Calcium in Tablets

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    A Reversed-Phase Liquid Chromatographic (RP-LC) assay method was developed for the quantitative determination of atorvastatin calcium in the presence of its degradation products. The assay involved an isocratic elution of atorvastatin calcium in a LiChroCARTR 250*4 mm HPLC Cartridge LiChrospherR 100 RP-18 (5 ÎŒm) column using a mobile phase consisting of 0.1% acetic acid solution: acetonitrile (45:55, v/v), pH = 3.8. The flow rate was 0.8 mL/min and the analytes monitored at 246 nm. The assay method was found to be linear from 8.13 to 23.77 ÎŒg/mL. All the validation parameters were within the acceptance range. The developed method was successfully applied to estimate the amount of atorvastatin calcium in tablets.Fil: Simionato, Laura Daniela. Universidad de Buenos Aires. Facultad de Farmacia y BioquĂ­mica. Departamento de TecnologĂ­a FarmacĂ©utica; ArgentinaFil: Ferello, L.. Universidad de Buenos Aires. Facultad de Farmacia y BioquĂ­mica. Departamento de TecnologĂ­a FarmacĂ©utica; ArgentinaFil: Stamer. S.. Universidad de Buenos Aires. Facultad de Farmacia y BioquĂ­mica. Departamento de TecnologĂ­a FarmacĂ©utica; ArgentinaFil: Repetto, M. F.. Universidad de Buenos Aires. Facultad de Farmacia y BioquĂ­mica. Departamento de TecnologĂ­a FarmacĂ©utica; ArgentinaFil: Zubata, P. D.. Universidad de Buenos Aires. Facultad de Farmacia y BioquĂ­mica. Departamento de TecnologĂ­a FarmacĂ©utica; ArgentinaFil: Segall, Adriana Ines. Universidad de Buenos Aires. Facultad de Farmacia y BioquĂ­mica. Departamento de TecnologĂ­a FarmacĂ©utica; Argentina. Consejo Nacional de Investigaciones CientĂ­ficas y TĂ©cnicas. Oficina de CoordinaciĂłn Administrativa Houssay; Argentin

    Local seismic response studies in the north-western portion of the August 24th, 2016 Mw 6.0 earthquake affected area. The case of Visso village (Central Apennines).

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    In this work, we investigate the possible causes of the differential damaging observed in Visso village (Central Apennines, about 28 km north from the August 24th, 2016 Mw 6.0 earthquake epicenter). Following insights from the available geological cartography at 1:10.000 scale, a preliminary geophysical survey has been performed in the damaged area in order to constrain geometries and extent of the subsoil lithotypes. Then, these results have been used to retrieve a Vs profile close to the most heavily damaged buildings. This latter has been used as input for a numerical analysis aimed at deriving the motion at the ground level in the study area. In particular, a linear equivalent simulation has been performed by means of EERA code and the waveform has been obtained convolving the time history recorded during the August 24th, 2016 mainshock at Spoleto Monteluco (SPM) site. Our preliminary results indicate a possible correlation of damaging to the thickness and shape of the geological units. Nevertheless, further analyses are necessary to highlight any 2D basin and / non- linear soil behaviour effects in order to compare them to the intrinsic buildings vulnerability, according to the EMS98 guidelines

    Follow-Up of Coiled Cerebral Aneurysms at 3T: Comparison of 3D Time-of-Flight MR Angiography and Contrast-Enhanced MR Angiography

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    BACKGROUND AND PURPOSE: Our aim was to compare contrast-enhanced MR angiography (CE-MRA) and 3D time-of-flight (TOF) MRA at 3T for follow-up of coiled cerebral aneurysms. MATERIALS AND METHODS: Fifty-two patients treated with Guglielmi detachable coils for 54 cerebral aneurysms were evaluated at 3T MRA. 3D TOF MRA (TR/TE = 23/3.5; SENSE factor = 2.5) and CE-MRA by using a 3D ultrafast gradient-echo sequence (TR/TE = 5.9/1.8; SENSE factor = 3) enhanced with 0.1-mmol/kg gadobenate dimeglumine were performed in the same session. Source images, 3D maximum intensity projection, 3D shaded surface display, and/or 3D volume-rendered reconstructions were evaluated in terms of aneurysm occlusion/patency and artifact presence. RESULTS: In terms of clinical classification, the 2 MRA sequences were equivalent for 53 of the 54 treated aneurysms: 21 were considered fully occluded, whereas 16 were considered to have a residual neck and 16 were considered residually patent at follow-up MRA. The remaining aneurysm appeared fully occluded at TOF MRA but had a residual patent neck at CE-MRA. Visualization of residual aneurysm patency was significantly ( P = .001) better with CE-MRA compared with TOF MRA for 10 (31.3%) of the 32 treated aneurysms considered residually patent with both sequences. Coil artifacts were present in 5 cases at TOF MRA but in none at CE-MRA. No relationship was apparent between the visualization of patency and either the size of the aneurysm or the interval between embolization and follow-up. CONCLUSION: At follow-up MRA at 3T, unenhanced TOF and CE-MRA sequences are similarly effective at classifying coiled aneurysms as occluded or residually patent. However, CE-MRA is superior to TOF MRA for visualization of residual patency and is associated with fewer artifacts

    A Virtual Tube Delay Effect

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    A virtual tube delay effect based on the real-time simulation of acoustic wave propagation in a garden hose is presented. The paper describes the acoustic measurements conducted and the analysis of the sound propagation in long narrow tubes. The obtained impulse responses are used to design delay lines and digital filters, which simulate the propagation delay, losses, and reflections from the end of the tube which may be open, closed, or acoustically attenuated. A study on the reflection caused by a finite-length tube is described. The resulting system consists of a digital waveguide model and produces delay effects having a realistic low-pass filtering. A stereo delay effect plugin in PURE DATA has been implemented and it is described here

    Effect of nascent entrepreneurs' training on their stress: The role of gender and participants' interaction

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    Purpose A career in entrepreneurship is stressful, especially during the start-up phase. Training programs for these nascent entrepreneurs are designed to improve entrepreneurial competencies and, more generally to generate learnings. Although learning outcomes can reduce stress, the conditions under which this can happen are not fully understood. The study looks particularly at the effect of learning, interaction with other participants and gender. Design/methodology/approach A six-month three-wave longitudinal study of 120 nascent entrepreneurs has been conducted to investigate the before-and-after effects of training on stress reduction. The training is specially designed to develop competencies, share knowledge about business creation and support the development of the project, not to reduce per se stress. Findings The training has no direct effect on stress levels. However, results indicate that interacting with others has a positive moderating effect on training as stress reduction, just as gender has. Specifically, women reduce their stress through training while men see theirs increasing. The authors conclude that breaking isolation through training is a relevant way to reduce entrepreneurial stress for nascent entrepreneurs. Research limitations/implications Training programs offer different ways to deliver the learning content (online, in cohorts, in the continuous entrance, etc.). The findings of this study suggest ensuring that the participants will have opportunities to interact with others as it reduces the stress on nascent entrepreneurs. Nevertheless, the authors cannot demonstrate that this has a long-term effect as our timeframe is limited to six months. Originality/value This research investigates the stress-reduction effect of training, which is not a common outcome studied related to training. This highlights the importance of looking at other more distal outcomes as nascent entrepreneurs may seek other peripheral outcomes from training, like seeking a sense of belonging or wanting to break isolation

    Non-perturbative thermal flows and resummations

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    We construct a functional renormalisation group for thermal fluctuations. Thermal resummations are naturally built in, and the infrared problem of thermal fluctuations is well under control. The viability of the approach is exemplified for thermal scalar field theories. In gauge theories the present setting allows for the construction of a gauge-invariant thermal renormalisation group.Comment: 16 pages, eq (38) added to match published versio

    Efeito da adubação potåssica no sabor de morangos.

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    O objetivo deste trabalho foi avaliar o efeito da adubação potåssica sobre o sabor de morangos das cultivares Camino Real, Festival e Oso Grande
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