6,100 research outputs found
— History of the Zoology in the University of Córdoba: the early years (1872-1916)
Se ofrece una reseña histórica de las etapas iniciales de la Zoología en la Universidad de Córdoba (Argentina), desde la fundación de la Facultad de Ciencias Exactas, Físicas y Naturales en el siglo XIX, hasta el retiro del último de los primeros académicos en 1916. Se presentan datos biográficos de cada uno de los Profesores que actuaron en ese período, y se destacan sus contribuciones, logros o anécdotas más relevantes desde un punto de vista personal o institucional. En orden cronológico, ocuparon la Cátedra de Zoología el holandés Hendrik Weyenbergh (en dos períodos, entre 1872 y 1884), Carlos Berg (sólo dos meses, en 1875), Florentino Ameghino (1884-1886), Adolfo Doering (un breve interinato en 1886-1887, luego titular entre 1892 y 1916) y Johannes Frenzel (1887-1891). Ninguno de los científicos mencionados dejaría discípulos en la especialidad. Al culminar esta etapa inicial, los estudios de Zoología en Córdoba pasarían por un largo período de incertidumbre. Se realizan breves referencias a los avances o retrocesos del dictado de la asignatura Zoología a lo largo del lapso abordado.This paper offers a brief historical account of the initial stages of the zoological sciences at the University of Córdoba (Argentina), from the establishment of the Faculty of Exact, Physical and Natural Sciences in the XIXth century, up to the academic retirement of the last of the founders in 1916. Biographical information on each of the Professors during that period is provided, highlighting their most relevant contributions, achievements and anecdotes from a personal or institutional point of view. In a chronological order, the Chair of Zoology was held by the Dutch zoologist Hendrik Weyenbergh (in two periods, between 1872 and 1884), Carlos Berg (for just two months, in 1875), Florentino Ameghino (1884-1886), Adolfo Doering (provisionally in 1886-1887, then titular Professor in 1892-1916) and Johannes Frenzel (1887-1891). None of the aforementioned scientists left followers. At the end of this initial stage, the zoological studies in Córdoba underwent a long period of uncertainty. Some comments on the progresses or withdrawals on the teaching of Zoology along the referred period are also given.Fil: Acosta, Luis Eduardo. Universidad Nacional de Córdoba; Argentina. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Cordoba. Instituto de Diversidad y Ecologia Animal; Argentin
De Biedermann por Andorra hasta Biografie. La obra dramática de Frisch en España
This paper dels with the reception in Spain of three works by Frisch (1911-1991), namely, Biedermann y los incendiarios (Biedermann und die Brandstifter), 1958, Andorra, 1961, and Biografía (Biografie), 1967. These three plays have been produced for the stage in Spain by professional or commercial companies. Both the reception and the interpretation of the plays are seen from the perspective of comparativist methodologies. One the one hand, the way in which critics in its native tongue considered them is taken into account; on the other hand careful attention is paid to the peculiar way in which these works were received in Spain as a direct consequence of specific literary, cultural and historical conditions. Conflation of these two disparate analyses has brought about a new form of understanding
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Statistical Vibro-Acoustic Modelling of Nonlinear Systems with Applications in Vehicles
Designing quiet cars has become an important issue in the automotive industry, where passive and active noise control techniques can be employed to improve the acoustic comfort without compromising the vehicle performance. At the design stage of a noise control system, the estimation of the structure-borne sound pressure levels in the car cabin is a challenging problem, as uncertainties in a physical structural-acoustic system have an impact on the vehicle dynamics at high frequencies. Additionally, the response of the system can be affected by nonlinearities in the vibrations transmission path. Therefore, this research has been focused in developing computationally efficient vibro-acoustic models to predict the statistical structural-acoustic response of a system to random inputs, as well as analysing the degree of dependency of the response to nonlinear behaviour in the interface between the excitation and the structure.
Key aspects of the impact that a nonlinear transmission path might have in the response of a statistical structural-acoustic system, were investigated from an equivalent damper model of the structural vibrating subsystem, under the assumption of weak acoustic coupling and the infinite plate theory. Numerical data in the time domain were generated from the simplified nonlinear system excited by random inputs with known power spectral density. The effects of nonlinearities were observed and quantified in the power spectral density of the response, as well as in the reduction of coherence between the input and output. Additionally, the Wiener theory in the frequency domain has been explored to estimate the degree of contribution of a nonlinearity of second order to the total response of the system.
Finally, an extended hybrid Finite Element-Statistical Energy Analysis (FE-SEA) model was proposed to analyse the response of a deterministic-statistic structural-acoustic system, where the nonlinear transmission path is considered as a deterministic structure. The equations of an existing FE-SEA approach, based on the diffuse field reciprocity, have been generalised to include prescribed displacements as inputs, in addition to external forces. The nonlinear analysis with the FE-SEA approach has been carried out by adopting the concept of equivalent linearisation of the deterministic dynamic stiffness matrix, and the capability of the approach has been validated against experimental data from a physical nonlinear structural-acoustic setup
Zinc-Mediated Regulatory Function of PSD-95 on NMDAR at Post-Synapses
Postsynaptic density-95 (PSD-95) is a membrane-associated guanylate kinase that mediates localization of receptors in the excitatory postsynaptic density. It has been reported that PSD-95 mediates postsynaptic localization of NMDA receptors and anchors postsynaptic AMPAR receptors mainly through its postsynaptic membrane targeting by its N-terminal palmitoylation. Recent studies have shown that Ca2+/calmodulin blocks palmitoylation of PSD-95 by binding at the N-terminus of PSD-95, which promotes dissociation of PSD-95 from the postsynaptic membrane and causes loss of surface AMPARs in cultured neurons. Another metal ion zinc is found in various areas of the brain. As an endogenous neuromodulator, zinc plays a role in synaptic transmission and is important in the maintenance of postsynaptic density stability. However, whether or not Zn2+ interacts with PSD-95 and regulates PSD-95 modification remain unknown. This study was carried out in human embryonic kidney 293 (HEK-293) cells. Cells were transfected with PSD-95 plasmids. After incubation for 48 hours, the cells were stimulated with 0.1 mM ZnCl2 for 5 min. And then the cells were harvested and the palmitoylation of PSD-95 was assessed using acyl-biotinyl exchange (ABE) method and Western blot. Our data showed that zinc stimulation decreased PSD-95 palmitoylation by 40%. The potential effect of the Zn2+-induced depalmitoylation of PSD-95 will be further studied, such as PSD-95 postsynaptic stability and PSD-95 postsynaptic localization. And more work needs to be done to unveil the mechanism underlying the impact of the depalmitoylation of PSD-95 on the postsynaptic localization of NMDARs and AMPRs in response to zinc stimulation
Qorimayus, a new genus of relictual, high-altitude harvestmen from western Argentina (Arachnida, Opiliones, Gonyleptidae) reveals trans-Andean phylogenetic links
A new genus of Gonyleptidae Pachylinae, Qorimayus gen. nov., is described to place the high-altitude species originally named Parabalta alticola Ringuelet, endemic to Sierra de Famatina, western Argentina. While classical exomorphological features do not separate this new genus from Parabalta Roewer or Pachyloides Holmberg (to which the species was formerly combined), male genitalic features, especially the shape of the ventral process of stylus, differ clearly. In turn, penis morphology suggests the systematic relationship of Qorimayus gen. nov. with the Chilean genera Metabalta Roewer and Nanophareus Roewer. A cladistic analysis was performed to test the phylogenetic affinities of the new genus; 28 terminals were used, comprising selected species of Parabalta, Pachyloides, Metabalta and Nanophareus, as well as other Gonyleptidae to represent the ‘subtropical’ and the ‘Chilean’ opiliofaunistic elements; the most external outgroups included one cosmetid, one metasarcid and one nomoclastid. Results supported the recognition of Qorimayus as an independent genus, and its close relationship with the Chilean genera Metabalta and Nanophareus. A detailed redescription of Qorimayus alticola comb. nov., along with some habitat notes are given. The presumed zoogeographical links of this endemic species with the central Chilean opiliofauna are briefly discussed.Fil: Acosta, Luis Eduardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Diversidad y Ecología Animal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto de Diversidad y Ecología Animal; Argentin
Bioclimatic profile and potential distribution of the Mesopotamian harvestman Discocyrtus testudineus (Holmberg, 1876) (Opiliones, Gonyleptidae)
The geographic range of the Neotropical harvestman Discocyrtus testudineus (Holmberg, 1876) (Gonyleptidae) is addressed by determining the species’ bioclimatic profile and modeling its potential distribution. Analysis was performed on a record set of 71 localities, including literature records and 34 new localities reported here. The bioclimatic profile was characterized through extreme, median and dispersion features of the values of 19 bioclimatic variables across the record set. Predictive models were built with the presence-only methods MAXENT and, secondarily, BIOCLIM. Discocyrtus testudineus is a typical Mesopotamian harvestman, spreading across a wide region along the middle and lower Paraná River in subtropical / temperate Argentina, and extending, more or less continuously, up to the central province of Córdoba. Apparently diverging records (Paso de los Libres, on the Uruguay River, and Quilmes, on the southern coast of Rio de la Plata) proved to be predictable, even if suppressed from the dataset. Comparisons of cumulative frequencies curves and dispersion features (box-plots) were made with Discocyrtus dilatatus Sørensen, 1884 and Gryne orensis (Sørensen, 1884), other Mesopotamian species for which bioclimatic data are available. The relative importance of the bioclimatic variables used for modeling was also estimated.Fil: Acosta, Luis Eduardo. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Cordoba. Instituto de Diversidad y Ecologia Animal; Argentin
A comprehensive analysis of SVPWM for a Five-phase VSI based on SiC devices applied to motor drives
© 2019 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes,creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.This paper presents a comprehensive analysis of SVPWM for a five-phase VSI based on SiC devices applied to motor drives. The modulation techniques analyzed use medium and large vectors to reach the reference vector. The 2L SVPWM uses two large space vectors, and the generated output signal contain low frequency harmonics. 2L+2M SVPWM uses two large and two medium space vectors. This technique provides good power loss distribution. 4L SVPWM works with the activation of four large space vectors. This modulation is able to generate low common-mode voltage. The performance and main features are analyzed using Matlab/Simulink and PLECS blockset software. Power losses, total harmonic distortion and common-mode voltage are compared and evaluated.Postprint (author's final draft
Webquest y cine en la historia contemporánea : una experiencia de investigación-acción curricular en bachillerato
Las TIC representan una oportunidad para la integración en la enseñanza de estrategias de aprendizaje colaborativo, más activas, que sitúen al estudiante en el centro de su proceso de adquisición de conocimiento. No obstante, la posibilidad de un cambio real de paradigma no es automático ni fácil, y exige por parte de los docentes la identificación, el análisis y la superación de resistencias y dificultades. En este sentido, presentamos una experiencia propia de investigación-acción que ha recurrido a la Webquest como método para la mejora en la didáctica de la historia desde el empleo del cine como recurso.The ICTs represent an opportunity to incorporate more active collaborative learning strategies in the teaching practise, which can put the students in the center of their own process of knowledge acquisition. However, the possibility of a real change in the paradigm is not something easy or automatic, and teachers are forced to identify, analyse and overcome difficulties and reluctances. In that respect, we introduce here our own action research experience which has made use of Webquests as a method to improve History Methodology using cinema as a resource
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