Showing papers by "National University of Cuyo published in 1997"
TL;DR: It is demonstrated in this report that capacitation of cauda epididymal mouse sperm in vitro was accompanied by a time-dependent increase in PK-A activity, and cAMP is a key intermediary second messenger in regulating protein tyrosine phosphorylation and capacitation.
195 citations
TL;DR: In this paper, the authors studied the partition function for the low-energy edge excitations of the incompressible electron fluid, which is invariant under modular transformations of the toroidal geometry made by the angular variable and the compact Euclidean time.
69 citations
TL;DR: Results suggest that rab proteins are involved in the regulation of fusion in streptolysin O-permeabilized J774-E macrophages, and indicate that NSF is required for fusion between phagosomes and lysosomes.
67 citations
TL;DR: In this paper, the authors compared two of the most important structural reforms of social security in Latin America: the Chilean private fully funded system, and the public/private Argentinean "integrated" (pay-as-you-go/fully funded) program.
54 citations
TL;DR: The Leydig cells of Lagostomu maximus maximus show deep changes alongside the reproductive cycle, and the photoperiod variations, through pineal hypothalamus pituitary axis and the hormone melatonin, are probably responsible for them.
Abstract: The Leydig cells of viscacha (seasonal rodent) show cytoplasmic hypertrophy and regional distribution during the breeding period (summer-autumn). The dominant organelles are smooth endoplasmic reticulum (SER) and mitochondria. A moderately well-developed Golgi, abundant lipid inclusions, dense bodies like lysosomes in different stages, and centrioles are observed. Extensive or focal desmosome and gap-like junctions between neighbouring Leydig cells are present. These cells exhibit an evident hypotrophy and an increase in the number of dense bodies during the gonadal regression in winter (July and August). Cells in different stages of involution are observed in this period. Their nuclei are irregular and heterochromatic. The cytoplasm contains few mitochondria. The vesicular SER is scarse. Irregular and large intercellular spaces with microvilli and amorphous material are present. The junctional complexes are absent. The nuclear and cytoplasmic volume and development of SER and mitochondria increase during the recovery period (spring). The lipid inclusions decrease. Dilatations of the intercellular space with microvilli and limited by focal desmosome-like junctions are observed. In conclusion, the Leydig cells of Lagostomus maximus maximus show deep changes alongside the reproductive cycle. The photoperiod variations, through pineal hypothalamus pituitary axis and the hormone melatonin, are probably responsible for them. Moreover, the fall of serum and tubular testosterone would be one of the factors responsible for gonadal regression.
43 citations
TL;DR: Water potential treatments showed that this species is adapted to germinate under conditions of water stress, and temperature, ruminal, mechanical and physical–chemical scarification, as well as water potential and pH effects on albaida seed germination were tested.
43 citations
TL;DR: In this paper, the generalized Langevin process has been studied in the presence of arbitrary noise and its characteristic functional properties have been built up, and the generalized Kubo oscillator has been worked out and all its 1 time moments have been calculated for different noise structures.
Abstract: Langevin-like equations have been studied in the presence of arbitrary noise. The characteristic functional of the generalized Langevin process has been built up. Exact results for all cumulants are given. Particular stress has been put on the Campbell, dichotomous and radioactive decay noises. Transient relaxation, susceptibility and diffusion constants for different (noisy) media have been sketched in order to exemplify the theory. The generalized Ornstein - Uhlenbeck and Wiener processes have been completely characterized. The generalized Kubo oscillator has been worked out and all its 1-time moments have been calculated for different noise structures.
43 citations
TL;DR: Because increased peroxidation was only associated with reductions in glutathione peroxidase activity irrespective of catalase activity, the selenoenzyme appears to be more important for detoxification of hydrogen peroxide in the heart.
30 citations
TL;DR: In the hippocampal formation histamine inhibits exploratory motivation and decreases emotionality by activating both types of histamine receptors, and the elevated asymmetric plus-maze appears to be a suitable technique to quantify exploration and possibly "anxiety".
Abstract: The possible role of histamine receptors in the hippocampal formation on the exploratory motivation and emotionality of the rat was studied. An elevated asymmetric plus-maze composed of 4 different arms (no walls, single high wall, high and low walls and two high walls) arranged at 90o angles was used. The exploration score, considered to be an index of exploratory motivation, and the permanency score, considered to be an index of emotionality (anxiety), were determined. Histamine was administered locally into the ventral hippocampus at three different doses (9, 45 and 90 nmol). Another group of rats was also microinjected with 45 nmol of pyrilamine (a histamine H1 receptor antagonist) or ranitidine (a histamine H2 receptor antagonist) in addition to 9 nmol of histamine in order to identify the possible type of histamine receptor involved. Histamine administration significantly inhibited the exploration score and increased the permanency score at the doses of 9 and 45 nmol in two of four arms. These effects were completely blocked by the administration of either histamine receptor antagonist. The present results suggest that in the hippocampal formation histamine inhibits exploratory motivation and decreases emotionality by activating both types of histamine receptors. Also, the elevated asymmetric plus-maze appears to be a suitable technique to quantify exploration and possibly" anxiety"
29 citations
02 Apr 1997-Nuclear Instruments & Methods in Physics Research Section B-beam Interactions With Materials and Atoms
TL;DR: In this paper, the authors review different models which have been proposed to explain these new observations, within the general framework of the theory of final-state interaction, and also analyze the presence of similar effects in other scattering processes.
Abstract: The distribution of electrons emitted in atomic collisions often exhibits a cusp-shaped peak centered at a velocity equal to that of the incident projectile. In the case of outgoing “charged” projectiles, this effect is assumed to be due to the long-range nature of the Coulomb electron-projectile interaction in the final state. However, measurements made by the Debrecen and Frankfurt groups of cusp electrons in coincidence with neutral H and He ejectiles have confronted the theorist with new questions and apparently conflicting evidence. We review different models which have been proposed to explain these new observations, within the general framework of the theory of final-state interaction. We also analyze the presence of similar effects in other scattering processes.
28 citations
TL;DR: In this paper, Fe, Co, and Co35Fe65 were sputter deposited onto the surface of porous nanochannel alumina substrates producing nanostructured contiguous magnetic networks.
Abstract: Films of Fe, Co, and Co35Fe65 alloy have been sputter deposited onto the surface of porous nanochannel alumina substrates producing nanostructured contiguous magnetic “networks.” Large room temperature coercivities have been measured which approximately scale with the bulk saturation magnetization of the material used. In the as-deposited state the largest coercivities (e.g., >1000 Oe for Co35Fe65) are observed in ∼15-nm-thick networks deposited on the smallest commercially available pore size substrates (those having an average pore diameter of ∼20 nm and a wall thickness of ∼15 nm). Preliminary studies of the effects of annealing indicate that coercivities can be substantially increased (by as much as ∼50%) with an appropriate post-deposition thermal treatment.
TL;DR: In this paper, the authors show the results of the hysteresis evolution, which can be described over three regimes according to the precipitate size, and these regimes will be related to microscopic observations of defects created around the precipitates.
TL;DR: In this article, the translational oscillations of a sphere in liquid helium have been measured as a way of studying superfluid turbulence, and good agreement was found between measured and calculated quantities.
Abstract: The translational oscillations of a sphere in liquid helium have been measured as a way of studying superfluid turbulence. Experiments were carried out in the laminar flow regime for reference purposes, and good agreement found between measured and calculated quantities. In the turbulent region, the dissipation is found to be proportional to the square of the velocity of the sphere, as found previously by other workers. For high vibration amplitudes there is an increase in the hydrodynamic mass. This seems to scale with the superfluid fraction in a way that strongly suggests that the superfluid component plays an important role in the turbulent regime.
01 Jan 1997
TL;DR: In this paper, a lectura desdoblada del relato borgeano is presented, in which a primera lectura proporciona una estructura temporal for la narración, and a segunda, una esquema espacial de significados ulteriores.
Abstract: En este trabajo propongo un procedimiento mas sistematico para desentranarlos ";esquemas laberinticos"; que Borges ";prodiga"; ";en su obra";. 1 Propongo hacer una lectura desdoblada del relato borgeano. Una primera lectura nos proporciona una estructura temporal para la narracion, y una segunda, una estructura espacial de significados ulteriores. La primera generalmente se consolida en las famosas ";cajas chinas"; con multiples entradas y salidas a diferentes planos de la realidad-irrealidad. La igualdad de las cajas esta dada por un intrincado esquema de ";ecos y vigilancias";, liaisons tematicos que enriquecen nuestra compresion de la narracion. La segunda conforma un esquema espacial donde la distribucion de personajes y eventos en diferentes paneles es proporcional y simetrica. El diseno asi obtenido impone una ulterior interpretacion al corpus narrativo.2
TL;DR: In this paper, a semi-empirical modified neglect of diatomic overlap and Austin model 1 (AM1) methods are presented for hexakis $(n$-alkoxy) triphenylene with $n=1$ and 4.
Abstract: Quantum chemical calculations by means of the semiempirical modified neglect of diatomic overlap and Austin model 1 (AM1) methods are presented for hexakis $(n$-alkoxy) triphenylene with $n=1$ and 4. The predicted molecular structures by the self-consistent electronic field are presented and discussed. The optimized geometries are then used to study the interaction between two molecules and the possible origin of the different experimentally observed conducting properties. In addition, the effect of dynamic and static disorder in the transport properties is briefly discussed in terms of the calculated electronic properties. Finally, a few basic aspects of the electron-doping process with AlCl${}_{3}$ are bestowed.
TL;DR: Crude protein, energy, cell wall, ash and fat content of the five most important browse species of the Mendoza plain were determined and showed high mean protein and energy concentration in both the growing season and dry season.
TL;DR: In this paper, the elemental composition of lichens from remote southern South America regions has been studied with analytical and statistical techniques to determine if the values obtained reflect species, growth forms or habitat characteristics.
Abstract: The elemental composition of lichens from remote southern South America regions has been studied with analytical and statistical techniques to determine if the values obtained reflect species, growth forms or habitat characteristics. The enrichment factors are calculated discriminated by species and collection site and compared with data available in the literature. The elemental concentrations are standardized and compared for different species. The information was statistically processed, a cluster analysis was performed using the three first principal axes of the PCA; the three groups formed are presented. Their relationship with the species, collection sites and the lichen growth forms are interpreted.
TL;DR: In this article, the authors deal with the topic of housing deficit and it concentrates on one of its aspects -overcrowding- The topic is linked with the changes undergone by the housing policies, the economic growth and the rising of new forms of poverty.
Abstract: This paper deals with the topic of housing deficit and it concentrates on one of its aspects -overcrowding- The topic is here linked with the changes undergone by the housing policies, the economic growth and the rising of new forms of poverty. Special mention is made of the Provincia of Mendoza due to the characteristics there presents regards the magnitude and evolution of this phenomenon. It is here thus intended to call the attention to a topic most often neglected in political decisions regarding housing.
TL;DR: In this article, the authors studied the film thickness dependence of the remanent magnetization (delta M plots), the magnetic viscosity, and the activation volumes of Fe thin films sputtered on commercial nanochannel alumina of 20 nm average pore diameter.
Abstract: We have studied the film thickness dependence of the remanent magnetization (delta M plots), the magnetic viscosity, and the activation volumes of Fe thin films sputtered on commercial nanochannel alumina of 20 nm average pore diameter. The films have the form of a contiguous interconnected network. A critical film thickness of φ∼20 nm defines two regions with very different magnetic behavior. For this critical value of φ we have found a maximum in the remanent coercivity, a minimum in the interparticle interaction parameter α, and a rapid increase in the magnetic viscosity, the irreversible susceptibility and the activation volume. Our results are interpreted in terms of the pinning effects caused by nonmagnetic inclusions. The functional relationship between the remanent coercivity and the activation volume is similar to the one found in long cylinders that reverse magnetization by a curling mechanism.
TL;DR: In this paper, the authors analyze the cost of irrigation water to the farmers in Mendoza Province consisting of three components; canal cleaning by the farmer, a water charge to their users Association (UA), and a water charges to the provincial Irrigation Department (DGI).
Abstract: The cost of irrigation water to the farmers in Mendoza Province consists of three components; canal cleaning by the farmer, a water charge to their Users Association (UA) and a water charge to the provincial Irrigation Department (DGI). The total cost of irrigation water shows large differences when the area of the UA is taken into consideration: farmers in smaller associations pay considerably more than those in large units. This is the case for all three groups of costs. The annual budgets of 31 UA's were analyzed with respect to 19 budget items prescribed by DGI. Several of these items contain a low percentage of the total budget. Further, they make participation of users during the annual meeting in which the budget is discussed and approved unnecessary difficult. We recommend to reduce the number of budget items to 7. Because of low collection levels (average 64%) the UA's spend a major part of their income on recurrent costs like salaries. As a result little is spent on maintenance and improvement of the system, creating dissatisfaction with the paying water users. Thus. a vicious circle needs to be broken about the deterioration of the system, dissatisfaction of users, less participation in the running of the Association and further deterioration. Recent experience shows that the discontinuation of flow to non-paying users in combination with improved water delivery services by the UA breaks the circle.
TL;DR: In this article, the evolution of conductivity in granular metal films, as a function of thickness and temperature, has been modeled by percolation within the framework of the theory of stochastic transport in disordered systems.
Abstract: The evolution of conductivity in granular metal films, as a function of thickness and temperature, has been modeled by percolation within the framework of the theory of stochastic transport in disordered systems. The model was analytically worked out by means of the effective-medium approximation. The analytical expression obtained spans the entire range of resistance, from insulating to globally superconducting behavior, with increasing thickness. Quasireentrant or local superconductivity was found in our results as a consequence of tunneling junctions allowed in the model. Experimental data on tin films are considered.
TL;DR: In this paper, a class of linear semi-infinite systems which satisfy the Weyl property is identified, the p-systems. And it is shown that any p-System contains an equivalent minimal subsystem.
TL;DR: In this article, the reaction cross sections averaged over a 235U fission neutron spectrum have been measured for the 45Sc(n,α)42K, 45Sc (n,2n)44Scg, and 45Sc n, 2n) 44Scm threshold reactions.
Abstract: The reaction cross sections averaged over a 235U fission neutron spectrum have been measured for the 45Sc(n,α)42K, 45Sc(n,2n)44Scg, and 45Sc(n,2n)44Scm threshold reactions. The values found for the...
TL;DR: In this paper, the authors proposed an algebraic approach to treat (1 + 1)-dimensional fermionic systems based on the idea of algebraic bosonization, which decomposes the elementary low-lying excitations around the Fermi surface in terms of basic building blocks carrying a representation of the algebra.
Abstract: We propose an approach to treating (1 + 1)-dimensional fermionic systems based on the idea of algebraic bosonization. This amounts to decomposing the elementary low-lying excitations around the Fermi surface in terms of basic building blocks carrying a representation of the algebra, which is the dynamical symmetry of the Fermi quantum incompressible fluid. This symmetry simply expresses the local particle number current conservation at the Fermi surface. The general approach is illustrated in detail through two examples: the Heisenberg and Calogero–Sutherland models, which allow comparison with the exact Bethe ansatz solution.
TL;DR: A residual-based a posteriori error estimator for finite element discretizations of the steady incompressible Navier{Stokes equations in the primitive variable formulation is discussed in this article.
Abstract: A residual-based a posteriori error estimator for finite element discretizations of the steady incompressible Navier{Stokes equations in the primitive variable formulation is discussed Though the estimator is similar to existing ones, an alternate derivation is presented, involving an abstract estimate that may prove of some intrinsic value The estimator is particularized to Hood{Taylor and modified Hood{Taylor finite elements and proved to be a global upper bound (up to a positive multiplicative constant) of the true error Numerical examples are provided to illustrate the performance of the resulting mesh adaptation process c 1997 John Wiley & Sons, Inc Numer Methods Partial Differential Eq 13: 561{574, 1997
TL;DR: In this article, the first-passage time distribution to reach the attractor of the stochastic differential equation is obtained by using a previously reported scheme: the Stochastic Path perturbation approach.
Abstract: The first-passage time distribution to reach the attractor of the stochastic differential equation is analytically obtained by using a previously reported scheme: the stochastic path perturbation approach. A second-order perturbation theory, in the small noise parameter , is introduced to analyse the random escape, of the stochastic paths, from the marginal unstable state X = 0. The anomalous fluctuation of the phase-space variable X(t) is analytically calculated by using the instanton-like approximation. We have carried out Monte Carlo simulations showing good agreement with our theoretical predictions.
TL;DR: In this paper, the authors investigated the micromechanisms of high temperature damping in an Al-Mg-Si industrial alloy by mechanical spectroscopy and found that lattice dislocations are firmly pinned by β or β' precipitates and lattice dislocation motion is controlled by the dragging of a complex Cottrell cloud composed by Mg and Si solute atoms.
Abstract: The micromechanisms of high temperature damping in an Al-Mg-Si industrial alloy are investigated by mechanical spectroscopy. The alloy in the as-received T6 state shows a relaxation peak at 483 K (1 Hz) with an activation energy H =1.6 eV and a limit relaxation time τ 0 = 1.3 x 10 -18 s. It is also found in solubilized, quenched and overaged samples. The internal friction maximum is attributed to a mechanism in which: a) lattice dislocations are firmly pinned by β or β' precipitates and b) lattice dislocation motion is controlled by the dragging of a complex Cottrell cloud composed by Mg and Si solute atoms. A good description of the experimental results is provided considering that the dislocation motion is controlled by transverse diffusion of Mg-Si pairs in the dislocation core. Relaxation mechanisms related with grain boundaries or precipitates can be discarded.
TL;DR: In this article, the Quantum Master Equation is derived by generalizing the van Kampen method, and a tight binding like hamiltonian in interaction with a phonon bath has been worked out within their approach.
TL;DR: Western blot analysis demonstrated the presence of proteins containing PKC-like cysteine-rich regions that are released from endosomal fractions by zinc chelators, indicating that the previously proposed zinc-dependent factor required for endosome fusion could be either a PKC isoform or a protein containing the phorbol ester-binding domain of PKC.