Showing papers by "Simón Bolívar University published in 1994"
Purdue University1, University of Granada2, Simón Bolívar University3, University of Valencia4, University of Murcia5, Autonomous University of Madrid6, Technical University of Madrid7, University of Nottingham8, University of Basel9, University of Rouen10, University College London11, Sapienza University of Rome12, University of Cincinnati13
TL;DR: An overview of the subject of robust Bayesian analysis is provided, one that is accessible to statisticians outside the field, and recent developments in the area are reviewed.
Abstract: Robust Bayesian analysis is the study of the sensitivity of Bayesian answers to uncertain inputs. This paper seeks to provide an overview of the subject, one that is accessible to statisticians outside the field. Recent developments in the area are also reviewed, though with very uneven emphasis.
587 citations
TL;DR: In this article, a mixture of isotactic polypropylene, PP and atactic polystyrene (PS) was used to study the nucleation mechanism of immiscible melt mixed blends of a crystallisable polyolefin (isotactic PP) and PS in a wide composition range.
Abstract: Immiscible melt mixed blends of a crystallisable polyolefin (isotactic polypropylene, PP) and atactic polystyrene (PS) were prepared in a wide composition range. It was found that when PP is the major component in the blend its crystallisation behaviour is not affected by blending it with PS. However if PP is the minor component, it will be dispersed in the immiscible PS matrix, hence the nucleation mechanism changes from predominantly heterogeneous to predominantly homogeneous as long as the size of the dispersed PP droplets is below a critical value (of the order of 1–2 μm).
109 citations
TL;DR: The results confirm the empirical observation that stoloniferous species B. mutica and E. polystachya are more tolerant to flooding thanks to adaptations typical of wetland plants such as hollow stolons which enhance oxygen diffusion to the roots and the development of adventitious rootlets that promotes water and nutrient absorption.
Abstract: Long dry seasons or permanent flooding, typical of tropical savannas, severely limit the growth of pasture plants. This study compares the responses of water relations, carbon assimilation and alcohol dehydrogenase (ADH) activity to drought and flooding in four perennial C4 grasses: the tufted or caespitose Hyparrhenia rufa and Andropogon gayanus (CIAT 621) and the stoloniferous Brachiaria mutica and Echinochloa polystachya.
89 citations
TL;DR: In this paper, a real-time interferometric measurement of the refractive index as a function of wavelength is presented, which consists in the spectral analysis of the interferogram which is built up when the specimen is placed in a Michelson interferometer illuminated with a broad-continuous spectrum light source.
86 citations
TL;DR: In this paper, the behaviour of the females accounted for most of the variation in individual alert rate and the behavior of the subordinate males accounted for the most variation in total alert rate in Capybaras.
68 citations
TL;DR: In this paper, an extension of the Schwarz and Sen formulation of dual symmetric actions is presented, and the new actions are also symmetric under dual transformations and present an infinite set of gauge symmetries.
53 citations
TL;DR: In this paper, a new method to evaluate the thermally stimulated depolarization current curves based on the direct signal analysis is first applied to the fitting of computer-generated curves to test its validity and accuracy.
Abstract: A new method to evaluate the thermally stimulated depolarization current curves based on the direct signal analysis is first applied here to the fitting of computer-generated curves to test its validity and accuracy. The method consists in finding the N elementary curves that best fit the experimental spectrum. The adjustment of the τ0 values associated with each energy bin is also included in the fitting. The results are presented for a monoenergetic peak and a peak generated with a Gaussian broadened energy distribution both with a single τ0. Good agreement is also found when a random noise of width σ0 ≤ 0.01 Jmax is added to the data to simulate experimental errors. Experimental complex curves corresponding to the γ and β overlapping relaxations in DGEBA-EDA epoxy resin system are separated into their fine structure components. The complex band corresponding to water dipoles physisorbed in different sites of the microporosity of bituminous coal is analyzed and different processes are identified. The results are compared to those performed on cleaned peaks. Finally, the TSDC peak corresponding to the glass transition temperature in bisphenol-A polycarbonate is analyzed and could only be fitted by using a Vogel-Fulcher expression for the temperature dependence of the relaxation times. © 1994 John Wiley & Sons, Inc.
46 citations
TL;DR: In this paper, a simple method for extracting the difference between the drain and source series resistances (Rd-Rs) in MOSFETs is presented, which is applicable for n-and p-channel MOSFLETs with any channel length.
Abstract: A simple method for extracting the difference between the drain and source series resistances (Rd – Rs) in MOSFETs is presented. This method is applicable for n- and p-channel MOSFETs with any channel length. The results show that the magnitude of (Rd – Rs) increases with the drain current.
30 citations
TL;DR: For a C*-algebra A with a conditional expectation Φ: A → A onto a subalgebra B, the linear decomposition A=B⊕H whereH=ker(Φ) was shown in this article.
Abstract: For aC*-algebraA with a conditional expectation Φ:A → A onto a subalgebraB we have the linear decompositionA=B⊕H whereH=ker(Φ). Since Φ preserves adjoints, it is also clear that a similar decomposition holds for the selfadjoint parts:As=Bs⊕Hs (we useVs={aeV;a*=a} for any subspaceV of A). Apply now the exponential function to each of the three termsAs,Bs, andHs. The results are: the setG+ of positive invertible elements ofA, the setB+ of positive invertible elements ofB, and the setC={eh;h*=h, Φ(h)=0}, respectively.
29 citations
TL;DR: In this article, the palladium-catalyzed coupling reaction of 1-propenyltributyltin with functionalized styryl bromides is described, and the latter undergoes a novel organotin-promoted dehydrobromination-coupling sequence to give a 1,3-enyne as final product.
29 citations
TL;DR: In this article, it was shown that soluble intermediates of pyrrole oxidation participate in the formation of the polymer and that nucleation and growth phenomena are not necessarily involved in the initial stages of polypyrrole deposition.
TL;DR: New solutions to the Wheeler-DeWitt equation are presented that reinforce the conjecture that the Jones Polynomial is a state of nonperturbative quantum gravity.
Abstract: We propose a new representation for gauge theories and quantum gravity. Alternatively, it can be viewed as a new framework for doing computations in the loop representation. It is based on the use of a novel mathematical structure that extends the group of loops into a Lie group. This extension allows the use of functional methods to solve the diffeomorphism and Hamiltonian constraint equations. It puts in a precise framework some of the regularization problems of the loop representation. It has practical advantages in the search for quantum states. Making use of it we are able to find a new solution to the Wheeler-DeWitt equation that reinforces the conjecture that the Jones polynomial is a quantum state of nonperturbative quantum gravity.
TL;DR: The results suggest involvement of NMDA receptors and NO and thus of long-term potentiation phenomena in learning and in memory consolidation, whereas other neuromodulatory systems related to Arg, and opiate receptors, are only involved inMemory consolidation.
Abstract: The effect of injections of selected amino acids and of N- methyl- D -aspartate (NMDA); morphine; and NMDA, nitric oxide (NO), and opioid inhibitors given before a maze-learning was investigated. Thirsty crickets (Pteronemobius sp) were trained to turn only to one side of a symmetrical Y-shaped maze using reinforcements with water. The insects retained the learned task 24 h later. N2 anoxia applied immediately after training produced retrograde amnesia. Injections of alanine (Ala), arganine (Arg), glutamine (Gln), morphine, or NMDA prior to training blocked the amnesic action of anoxia. Naloxone, an opioid antagonist, blocked long-term memory formation, but not learning, whereas hemoglobin or 2-amino-5-phosphonovaleric acid (APV), NO and NMDA antagonists respectively, blocked both. The antiamnesic effect of Morphine and Arg, but not that of Ala or NMDA was blocked by naloxone. The results suggest involvement of NMDA receptors and NO and thus of long-term potentiation phenomena in learning and in memory consolidation, whereas other neuromodulatory systems related to Arg, and opiate receptors, are only involved in memory consolidation.
TL;DR: In this article, an experimental study of shear and apparent elongational behavior of linear low density (LLDPE) and low-density polyethylene blends by means of capillary rheometry is presented.
Abstract: In this work we present an experimental study of shear and apparent elongational behavior of linear low-density (LLDPE) and low-density (LDPE) polyethylene blends by means of capillary rheometry. The characterization of these rheological properties is crucial in the design of a blend that combines the ease of processing of LDPE with the mechanical advantages of the LLDPE. Two different low-density polyethylenes and one common linear low-density polyethylene were used to prepare the blends. The results obtained indicate a strong sensitivity of the rheology of the blend to changes in the molecular weight of the LDPE employed. For the higher molecular weight LDPE, the shear viscosity of the blend was essentially equal to that of the LDPE homopolymer up to a concentration of 25% of LLDPE, whereas the apparent extensional viscosity was appreciably lower. For the lower molecular weight LDPE, the same trend was obtained regarding the shear viscosity, but in this case the apparent extensional viscosity of the blend was somewhat higher than that of the LDPE homopolymer.
TL;DR: In this article, a simple method to extract the effective channel length and the gate voltage dependent series resistance of p-channel MOSFETs was proposed, which is used at room and at liquid nitrogen temperatures on devices with mask channel lengths in the range of 0.6-2.0 #m.
Abstract: --We present a simple method to extract the effective channel length and the gate voltage dependent series resistance of p-channel MOSFETs. The method is used at room and at liquid nitrogen temperatures on devices with mask channel lengths in the range of 0.6-2.0 #m. The good agreement found at 77 and 300 K between the experimental drain current-voltage characteristics of the devices and those computed from the extracted parameter verifies the validity of the method. I. INTRODUCTION The benefits of operating CMOS devices at low temperature over traditional operation at room tem- perature have been described in many recent works. Some of these benefits are[l]: high carrier mobility; improved latch-up immunity; and low sub threshold current. Modeling and parameter extraction of the devices at liquid nitrogen temperature (77 K) present dissimilarities with respect to room temperature. For example, conventional methods[2-4] to extract the effective channel length, Lef r = Lm - AL, knowing the mask channel length, Lm, can give a physically unre- alistic negative value for AL at 77K. Since AL originates mainly from the lateral diffusion of the source and drain junctions, it should be a positive quantity. Although conventional methods have been successfully used[5] at 77 K for 2 pm ~< L m ~< 6/~m and V d < 40 mV, there are reports[6-8] in which they have failed with shorter channel lengths of 0.4 /~m ~<
TL;DR: Rates of marking by individuals were associated with social rank and decreased with group size, and the majority of marks with the snout gland was followed by marks with anal glands in the Venezuelan llanos.
Abstract: Capybaras, Hydrochaeris hydrochaeris , scent mark with a sebaceous snout gland and anal glands, either separately or in sequence. In the Venezuelan llanos, marking was observed 3,864 times. A minority of marks was associated with aggressive interaction, but most marks were deposited out of any obvious context. Males marked more often than females, and the majority of marks with the snout gland was followed by marks with anal glands. Rates of marking by individuals were associated with social rank and decreased with group size.
TL;DR: In this article, the question des attributs "relatifs" ou "relationnels" en determinant leur signification par rapport a la definition aristotelicienne de la substance and examinant la formulation grecque for une meilleure comprehension
Abstract: L'A. etudie dans l'oeuvre d'Aristote la question des attributs «relatifs» ou «relationnels» en determinant leur signification par rapport a la definition aristotelicienne de la substance et en examinant la formulation grecque pour une meilleure comprehension
01 Jan 1994
TL;DR: In order to assess the effects of a Behavioral Treatment Program in the control of primary hypertension, twenty one unmedicated hypertensives were randomly allocated to three groups: first, a treatment group (BHG) receiving a Behavioral treatment which included deep muscle relaxation, peripheral temperature Biofeedback and anxiety management training.
Abstract: In order to assess the effects of a Behavioral Treatment Program in the control of primary hypertension, twenty one unmedicated hypertensives were randomly allocated to three groups: first, a treatment group (BHG) receiving a Behavioral Treatment which included: deep muscle relaxation, peripheral temperature Biofeedback and anxiety management training; second, the placebo attention control group (PHG) and third, a control group of hypertensives too (CHG). Additionally, were compared with seven normotensives subjects (CNG). The post-treatment measures showed a significant reduction (p < 0.001) in systolic and diastolic values only in the (BHG). In a six months follow-up the (BHG) group still showed a significant reduction in the systolic and diastolic BP (p < 0.02; p < 0.01). Moreover individual variations in response to treatment were observed in this group, (BHG).
TL;DR: In this article, the authors consider a discrete set of competing sampling models and combine them with a suitable large class of priors to incorporate model robustness with respect to the prior.
TL;DR: In this paper, the effect of intramolecular coupling on the optical susceptibilities up to third order in the external field is studied using a model molecule consisting of two coupled harmonic curves of electronic energies with minima displaced in energy and nuclear coordinates.
TL;DR: Improvement in animal production by selection by selection based on chromosomal analysis has allowed for the erradication of abnormalities involved in fertility problems, especially that of the 1 29 translocation.
TL;DR: A new nondestructive method for determination of the outer diameter of optical fibers is described, based on observing interference maxima in the scattered light from a fiber that is side illuminated by a laser beam at oblique incidence.
Abstract: A new nondestructive method for determination of the outer diameter of optical fibers is described. The principle of this technique is based on observing interference maxima in the scattered light from a fiber that is side illuminated by a laser beam at oblique incidence. This technique is easy to implement and can be applied to a fiber with an inhomogeneous and large core.
TL;DR: In this article, the authors studied the origin of the extension thickening commonly observed when solutions of flexible polymers flow through porous media and ideal elongational flows and found that the coil-stretch transition of isolated polymer molecules in solution cannot be the only mechanism responsible for the extension thickness.
Abstract: In this work, we study the origin of the extension thickening commonly observed when solutions of flexible polymers flow through porous media and ideal elongational flows. We have used randomly packed beds of glass beads as porous media. We have performed experiments with closely monodisperse atactic polystyrene of different molecular weights dissolved in organic solvents. The use of a closely monodisperse polymer allowed us to make a more meaningful comparison between the results obtained using opposed jets and porous media flow, as compared to previous works on polydisperse polymers. The results indicate that the coil-stretch transition of isolated polymer molecules in solution cannot be the only mechanism responsible for the extension thickening. It is clear that part of the observed effect is due to the extension of isolated molecules, but the main factor causing a great increase in the elongation viscosity beyond a critical strain rate is the formation of transient entanglement networks.
TL;DR: In this article, a general closed module category with linearly ordered closed sub-categories is studied and properties of these categories are characterized by conditions on special objects, i.e. cogenerators or generators.
Abstract: In an earlier paper the first named authors investigated rings whose kernel functors are linearly ordered The main tool for describing prop-erties of such rings was the filter of ideals associated to a kernel functor In the present paper more generally closed module categories (ie closed under kernels, cokernels and direct sums) with linearly ordered closed sub-categories are studied Properties of these categories are given and they are characterized by conditions on special objects, ie cogenerators or generators
TL;DR: In this article, a simple method is presented to extract the effective channel length and series resistance of n-channel MOSFETs having 0.6-2.0 mu m mask channel lengths at room and liquid nitrogen temperatures.
Abstract: A simple method is presented to extract the effective channel length and series resistance of n-channel MOSFETs having 0.6-2.0 mu m mask channel lengths at room and liquid nitrogen temperatures. Our results show that the effective channel length increases and the series resistance decreases when the temperature is reduced from 300 to 77 K.
TL;DR: In this paper, the authors defined coherent states in deformed quantum mechanics as eigenstates of the annihilation operator of q-algebras and associated them with elements in a Hilbert space of analytic functions.
TL;DR: In this paper, the second-order rate constants in the micellar pseudo-phase are smaller than the secondorder constants in water, and they were determined quantitatively in terms of the pseudo phase ion exchange model.
Abstract: Cationic micelles of alkyltrimethylammonium chloride and bromide (alkyl = nC12H25, nC14H29, and nC16H33) catalyze and anionic micelles of sodium dodecyl sulfate inhibit the reaction of hydroxide ion with 2-phenoxyquinoxaline (1). Inert anions such as chloride, nitrate, mesylate, and n-butanosulfonate inhibit the reaction in CTABr by competing with OH− at the micellar surface. The overall micellar effects on rate in cationic micelles and dilute electrolyte can be treated quantitatively in terms of the pseudo-phase ion-exchange model. The determined second-order rate constants in the micellar pseudo-phase are smaller than the second-order constants in water. © 1994 John Wiley & Sons, Inc.
TL;DR: In this paper, a mathematical model was developed to predict heat transfer and integrated sterilization values during the hot-fill process of double concentrated tomato paste in glass jars, which was capable of predicting satisfactorily the time-temperature relationships during the air-cooling process following the hotfill process.
TL;DR: The results on oxygen consumption measurements of ant colonies showed a complex and non-linear relationship between colony size and energy consumption per unit mass, that can be explained by irreversible thermodynamics and catastrophe theory, whereas an additional exponential inverse relationship may be explanation by optimization principles.
Abstract: The potential usefulness of applications of two physical concepts to evolutionary biology was evaluated on ant societies. The optimization principle, which predicts a more efficient use of energy by more sophisticated societies, was contrasted to that of irreversible thermodynamics, predicting an increase in orderliness and thus an increase in energy consumption per unit of biomass. Our results on oxygen consumption measurements of ant colonies showed a complex and non-linear relationship between colony size and energy consumption per unit mass, that can be explained by irreversible thermodynamics and catastrophe theory, whereas an additional exponential inverse relationship may be explained by optimization principles. Thus, social complexity is related to energy consumption in a discontinuous manner, and seems to be bound by both negentropy content of a society and social-optimization mechanisms.