259 research outputs found
The SO(N) principal chiral field on a half-line
We investigate the integrability of the SO(N) principal chiral model on a
half-line, and find that mixed Dirichlet/Neumann boundary conditions (as well
as pure Dirichlet or Neumann) lead to infinitely many conserved charges
classically in involution. We use an anomaly-counting method to show that at
least one non-trivial example survives quantization, compare our results with
the proposed reflection matrices, and, based on these, make some preliminary
remarks about expected boundary bound-states.Comment: 7 pages, Late
Markov Chain Modeling of Polymer Translocation Through Pores
We solve the Chapman-Kolmogorov equation and study the exact splitting
probabilities of the general stochastic process which describes polymer
translocation through membrane pores within the broad class of Markov chains.
Transition probabilities which satisfy a specific balance constraint provide a
refinement of the Chuang-Kantor-Kardar relaxation picture of translocation,
allowing us to investigate finite size effects in the evaluation of dynamical
scaling exponents. We find that (i) previous Langevin simulation results can be
recovered only if corrections to the polymer mobility exponent are taken into
account and that (ii) the dynamical scaling exponents have a slow approach to
their predicted asymptotic values as the polymer's length increases. We also
address, along with strong support from additional numerical simulations, a
critical discussion which points in a clear way the viability of the Markov
chain approach put forward in this work.Comment: 17 pages, 5 figure
Instanton Theory of Burgers Shocks and Intermittency
A lagrangian approach to Burgers turbulence is carried out along the lines of
the field theoretical Martin-Siggia-Rose formalism of stochastic hydrodynamics.
We derive, from an analysis based on the hypothesis of unbroken galilean
invariance, the asymptotic form of the probability distribution function of
negative velocity-differences. The origin of Burgers intermittency is found to
rely on the dynamical coupling between shocks, identified to instantons, and
non-coherent background fluctuations, which, then, cannot be discarded in a
consistent statistical description of the flow.Comment: 7 pages; LaTe
How patients with insulin-treated type 1 and type 2 diabetes view their own and their physician's treatment goals.
To investigate the subjective treatment goals of insulin-treated diabetic patients.
297 type 1 and 205 type 2 diabetic patients, representative of the North-western Swiss population, filled out a self report questionnaire focusing on their own treatment goals using standardized measures wherever available. Factor analysis of the 16 items reflecting their treatment goals revealed four subscales (Crohnbach's alpha): High actual quality of life (0.73), weight reduction/maintenance and daily hassles (0.68), good medical care and knowledge (0.64) and good long term glucose control (0.71).
Good long term glucose control was the single most important main treatment goal for most patients (type 1: 60.2%, type 2: 49.7%, p = 0.025). However, both type 1 and type 2 diabetic patients believed that this goal - especially the value of HbA1c - was overestimated (both p <0.0001), while high actual quality of life was underestimated (p = 0.003 and p = 0.05, respectively) by their physicians compared to their own assessment. Good long term glucose control (OR 1.63, p = 0.003) and high actual quality of life (OR 2.17, p <0.0001) were more important and weight reduction/maintenance and coping with daily hassles (OR 0.75, p = 0.07) were slightly less important treatment goals for type 1 than for type 2 diabetic patients. These differences in goals were best associated with the mode of insulin therapy, self-monitoring, and with the extent of diabetes education.
Patients believe that physicians overestimate the importance of long term glucose control and underestimate the importance of actual quality of life. Diabetes education and self management have the largest impact on patients' own treatment goals
Pyrolysis of Olive Stone for Energy Purposes
Abstract Pyrolysis of biomass is a promising technology for the production of distributed and renewable energy on small and micro-scale since it produces a gas with relatively high calorific value, which can be burned in an internal combustion engine or in a microturbine; pyrolysis also generates by products (char and tar) which can be used to provide energy to the process or for cogeneration purposes. This research is aimed at the exploitation of waste from agricultural production processes, in particular olive mill wastes whose management has critical environmental and disposal costs; the yields of pyrogas, tar and char obtained from the pyrolysis of olive stone in a batch reactor was measured. Pyrogas produced is sampled through a line for the sampling of condensable substances in accordance with existing regulations, CEN/TS 15439, and once purified from water vapor and tars is analyzed with micro-GC. The data collected is used to perform mass and energy balances and to determine the content of tars and the Low Heating Value (LHV) of the gas produced
Special Theory of Relativity through the Doppler Effect
We present the special theory of relativity taking the Doppler effect as the
starting point, and derive several of its main effects, such as time dilation,
length contraction, addition of velocities, and the mass-energy relation, and
assuming energy and momentum conservation, we discuss how to introduce the
4-momentum in a natural way. We also use the Doppler effect to explain the
"twin paradox", and its version on a cylinder. As a by-product we discuss
Bell's spaceship paradox, and the Lorentz transformation for arbitrary
velocities in one dimension.Comment: 20 pages, 1 figur
Log-Poisson Cascade Description of Turbulent Velocity Gradient Statistics
The Log-Poisson phenomenological description of the turbulent energy cascade
is evoked to discuss high-order statistics of velocity derivatives and the
mapping between their probability distribution functions at different Reynolds
numbers. The striking confirmation of theoretical predictions suggests that
numerical solutions of the flow, obtained at low/moderate Reynolds numbers can
play an important quantitative role in the analysis of experimental high
Reynolds number phenomena, where small scales fluctuations are in general
inaccessible from direct numerical simulations
Desempenho produtivo de oleaginosas no Município de Jaguariúna/SP.
RESUMO: O trabalho analisa a experiência de cultivo de três espécies oleaginosas, amendoim, girassol e mamona, com potencial de uso para a produção de biodiesel, no município de Jaguariúna-SP. O trabalho foi conduzido em campo experimental da Embrapa Meio Ambiente, Jaguariúna-SP, no período entre novembro de 2008 a maio de 2009, utilizando quatro cultivares comerciais: uma de amendoim (IAC8116), duas de girassol (Embrapa 122 e M734) e uma de mamona (IAC2028) e foram avaliados: a) período para emergência de plântulas; b) início do florescimento; c) ciclo total da cultura; d) rendimento final de grãos; e) peso de 100 grãos. Os dados levantados foram analisados pela estatística descritiva e os resultados apontaram para o desempenho satisfatório das três oleaginosas. O rendimento do amendoim foi de 2998 kg ha-1, com ciclo total de 129 dias; para girassol as médias foram superiores a 2100 kg ha-1 e o ciclo entre 90-106 dias; para mamona a produtividade foi de 1260 kg ha-1 aos 187 dias. Conclui-se que as cultivares de amendoim (IAC8116), girassol (Embrapa 122 e M734) e mamona (IAC2028) possuem rendimentos satisfatórios no município de Jaguariúna-SP. O amendoim e o girassol podem ser importantes alternativas para maiores estudos em sucessão à cana-de-açúcar, enquanto a mamona se mostra mais viável como cultura principal para pequenos produtores, tendo em vista o ciclo longo
Circulation Statistics in Three-Dimensional Turbulent Flows
We study the large limit of the loop-dependent characteristic
functional , related
to the probability density function (PDF) of the circulation around a closed
contour . The analysis is carried out in the framework of the
Martin-Siggia-Rose field theory formulation of the turbulence problem, by means
of the saddle-point technique. Axisymmetric instantons, labelled by the
component of the strain field -- a partially annealed variable in
our formalism -- are obtained for a circular loop in the plane, with
radius defined in the inertial range. Fluctuations of the velocity field around
the saddle-point solutions are relevant, leading to the lorentzian asymptotic
behavior . The
subleading correction and the asymmetry between right and left PDF tails due to
parity breaking mechanisms are also investigated.Comment: Computations are discussed in a more detailed way; accepted for
publication in Physical Review
Multiband Photometry Evolution in the First Weeks of SN 2023ixf, a possible II-L Subtype Supernova
Multiband photometric observations and their evaluation to instrumental
magnitudes were performed using standard Johnson-Cousins filters (B, V, Rc) as
well r and g Sloan filters, and not standard ones (R, G, B, and Clear filters).
These were recorded from 9 observatories and from the MicroObservatory Robotic
Telescope Network. The results describe the rapid ascent towards the maximum
(2.5 magnitudes about in five days in the B filter) and the slow decrease after
the maximum (0.0425 +/- 0.02 magnitudes/day in the B filter). The results
highlight the strong variation of the B-V colour indices during the first 50
days (from -0.20 +/- 0.02 to +0.85 +/- 0.02) and V-R (from 0 +/- 0.01 to +0.50
+/- 0.01) after the explosion, presumably corresponding to the cooling of the
stellar photosphere. At 50 days after the explosion the magnitude decrease from
the maximum was observed to continue where it faded by 2.5 magnitudes (B
filter), thus we propose SN 2023ixf is a Type II, subtype L, supernova (SNe)
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