131 research outputs found
Goodness-of-fit tests of Gaussianity: constraints on the cumulants of the MAXIMA data
In this work, goodness-of-fit tests are adapted and applied to CMB maps to
detect possible non-Gaussianity. We use Shapiro-Francia test and two Smooth
goodness-of-fit tests: one developed by Rayner and Best and another one
developed by Thomas and Pierce. The Smooth tests test small and smooth
deviations of a prefixed probability function (in our case this is the
univariate Gaussian). Also, the Rayner and Best test informs us of the kind of
non-Gaussianity we have: excess of skewness, of kurtosis, and so on. These
tests are optimal when the data are independent. We simulate and analyse
non-Gaussian signals in order to study the power of these tests. These
non-Gaussian simulations are constructed using the Edgeworth expansion, and
assuming pixel-to-pixel independence. As an application, we test the
Gaussianity of the MAXIMA data. Results indicate that the MAXIMA data are
compatible with Gaussianity. Finally, the values of the skewness and kurtosis
of MAXIMA data are constrained by |S| \le 0.035 and |K| \le 0.036 at the 99%
confidence level.Comment: New Astronomy Reviews, in pres
Tests of Gaussianity
We review two powerful methods to test the Gaussianity of the cosmic
microwave background (CMB): one based on the distribution of spherical wavelet
coefficients and the other on smooth tests of goodness-of-fit. The spherical
wavelet families proposed to analyse the CMB are the Haar and the Mexican Hat
ones. The latter is preferred for detecting non-Gaussian homogeneous and
isotropic primordial models containing some amount of skewness or kurtosis.
Smooth tests of goodness-of-fit have recently been introduced in the field
showing some interesting properties. We will discuss the smooth tests of
goodness-of-fit developed by Rayner and Best for the univariate as well as for
the multivariate analysis.Comment: Proceedings of "The Cosmic Microwave Background and its
Polarization", New Astronomy Reviews, (eds. S. Hanany and K.A. Olive), in
pres
Use of superheated liquids for the extraction of non-volatile compounds from wood: HPLC studies
A study of the extraction of oak wood compounds using superheated water-ethanol mixtures ranging from 10 to 60% ethanol is reported. Identification and characterization of the extracted compounds have been made by high performance liquid chromatography. The extraction has been performed using the static mode by single or repetitive cycles. The variables affecting the extraction process have been studied and their optimum values established (extraction time: 50 min; pressure: 40 atm; extraction temperature: 180º C). The study allows to compare the non-volatile polyphenol fractions obtained in this way with those present in commercial samples with fully agreement between them. In addition, the method allows manipulation of the extract composition by changing the working pressure, temperature and water-ethanol ratio
Nuclear Apaf-1 and cytochrome c redistribution following stress-induced apoptosis
AbstractApoptotic protease activating factor-1 (Apaf-1) and cytochrome c are cofactors critical for inducing caspase-9 activation following stress-induced apoptosis. One consequence of caspase-9 activation is nuclear–cytoplasmic barrier disassembly, which is required for nuclear caspase-3 translocation. In the nucleus, caspase-3 triggers proteolysis of the caspase-activated DNA nuclease (CAD) inhibitor, causing CAD induction and subsequent DNA degradation. Here we demonstrate that apoptotic cells show perinuclear cytochrome c aggregation, which may be critical for nuclear redistribution of cytochrome c and Apaf-1. We thus indicate that the nuclear redistribution of these cofactors concurs with the previously reported caspase-9-induced nuclear disassembly, and may represent an early apoptotic hallmark
Entropic uncertainty relation for power-law wave packets
For the power-law quantum wave packet in configuration space, the variance of
the position observable may be divergent. Accordingly, the information-entropic
formulation of the uncertainty principle becomes more appropriate than the
Heisenberg-type formulation, since it involves only the finite quantities. It
is found that the total amount of entropic uncertainty converges to its lower
bound in the limit of a large value of the exponent.Comment: 10 pages, 3 figure
Voltage-dependent calcium influx in human sperm assessed by simultaneous optical detection of intracellular calcium and membrane potential
AbstractThere are several physiological and pharmacological evidences indicating that opening of voltage dependent calcium channels play a crucial role in the induction of the acrosome reaction in mammalian sperm. In mature sperm, physiological inductors of the acrosome reaction such as ZP3, a zona pellucida protein, and the steroid hormone progesterone, induce depolarization and calcium influx, which are required for the acrosome reaction. In this paper, we describe a voltage-dependent calcium influx present in human sperm. We report an experimental procedure that allows measurement of intracellular calcium and membrane potential simultaneously using the fluorescent dyes DiSC3(5) and Fura-2. We found that in human uncapacitated sperm, depolarization induces a nifedipine-insensitive calcium influx that, in most cases, was transient. Calcium influx was observed in the range of −60 to −15 mV (the range tested). At resting membrane potential (around −40 mV), potassium addition depolarized and induced calcium influx, but when the depolarization was preceded by a hyperpolarization (induced with valinomycin), calcium influx was remarkably enhanced, suggesting that at −40 mV, channels are in a putative inactivated state. When sperm was incubated in medium without calcium, calcium restoration caused calcium influx that depended on voltage, and decayed between 1 and 2 min after depolarization. Unlike ram, mouse or bovine sperm, in which an alkalinization is required to induce calcium influx with potassium, the voltage-dependent calcium influx observed in human sperm did not require an increase in internal or external pH. However, we observed that ammonium, which increases intracellular pH, enhanced the voltage-dependent calcium influx about 90%. Furthermore, depolarization by itself caused a small increase in intracellular pH suggesting that pH can be regulated by membrane potential in human sperm
Calcium and temperature effect on structural damage of hot air dried apple slices: Nonlinear irreversible thermodynamic approach and rehydration analysis
Mathematical models traditionally employed in fitting convective drying data do not use to report information about chemical and other physical changes different from the simple decrease in moisture content. In the present study, structural damage undergone by fresh and vacuum impregnated apple slices with different calcium lactate concentrations during convective drying at 30, 40 and 50 °C was analysed by applying equations derived from nonlinear irreversible thermodynamics to experimental data. According to the results obtained, vacuum impregnation with isotonic sucrose solution before drying at 30 °C provided maximum protection to cellular structure by promoting reversible deformations against irreversible breakages. On the contrary, cell walls strengthen with calcium had severe damaged during drying. Regarding air temperature, it was directly related both to the molar energy employed in deforming structures and the drying rate. These results were confirmed by analysing dried samples behaviour during further rehydration.Barrera Puigdollers, C.; Betoret Valls, N.; Betoret Valls, ME.; Fito Maupoey, P. (2016). Calcium and temperature effect on structural damage of hot air dried apple slices: Nonlinear irreversible thermodynamic approach and rehydration analysis. Journal of Food Engineering. 189:106-114. doi:10.1016/j.jfoodeng.2016.05.024S10611418
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