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Search Results: 1 - 10 of 476269 matches for " GUSTAVO A TORRES-MELLADO "
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Mycotrophy in Gilliesieae, a threatened and poorly known tribe of Alliaceae from central Chile Micotrofía en Gilliesieae, una tribu amenazada y poco conocida de Alliaceae de Chile central
Revista chilena de historia natural , 2012,
Abstract: The five known genera of Gilliesieae have their diversity center in the Mediterranean zone of central Chile, where many of their habitats are threatened by urban expansion, industrial and agroforestry activities, as well as other anthropogenic impacts. Very little is known about the biology of these particular geophytes, the majority of which currently have either vulnerable or endangered status, mainly due to their dispersed and small populations generally associated to remnants of native vegetation. As mycorrhizal associations are essential for soil resource acquisition and stress mitigation in most plants, our objective was to assess the hitherto unknown mycotrophic status of ten species of Gilliesieae from central Chile by qualitative and quantitative assessment of intraradical fungal structures. All sampled genera (Gethyum, Gilliesia, Miersia, Solaria, Speea) showed regular presence of arbuscular mycorrhiza, while other mycorrhizal or putatively mutualistic associations, like dark septate endophytes, were practically absent. Mycorrhizal colonization of fine roots reached a mean of ca. 45 % across all examined taxa, with highly variable values ranging from 9 % to 82 % in Miersia tenuiseta and Gilliesia curicana, respectively. The high level of mycorrhization indicates that arbuscular mycorrhiza should be considered for conservation strategies of threatened species or biotechnological use in plant propagation. The main future task is the identification of the associated fungal taxa. Los cinco géneros conocidos de Gilliesieae tienen su centro de diversidad en la zona mediterránea de Chile central, donde muchos de sus hábitats están amenazados por la expansión urbana, actividades industriales y agroforestales, así como otros impactos antropogénicos. Se sabe muy poco sobre la biología de estas particulares geófitas, que en la actualidad tienen en su mayoría estatus de vulnerable o en peligro de extinción, debido a sus poblaciones dispersas y pequenas, generalmente asociadas a remanentes de vegetación nativa. Dado que las asociaciones micorrícicas son esenciales para la adquisición de recursos del suelo y para la mitigación de estrés en la mayoría de las plantas, nuestro objetivo fue determinar el estatus micotrófico aún desconocido de diez especies de Gilliesieae de Chile central, mediante análisis cualitativos y cuantitativos de las estructuras fúngicas intrarradicales. Todos los géneros evaluados (Gethyum, Gilliesia, Miersia, Solaria, Speea) mostraron la presencia regular de micorrizas arbusculares, mientras que otras asociaciones micorrícicas o asoci
Orlando Sepúlveda Mellado,Luis A. Riveros Cornejo,Julio Chesta Peigna,Gustavo Carrasco Pérez
Revista INVI , 2004,
Cambios en la calidad de vida evaluada mediante baros (bariatric análisis and reporting outcomes system) en pacientes de obesidad mórbida intervenidos con la técnica de salmón Changes in quality of life assessed by means of baros (bariatric analysis and reporting outcomes system) in patients with morbid obesity subjected to salmon′s technique
Y Martínez Fuentes,C Mellado Pastor,Moreno-Torres Herrera,A Pérez de la Cruz
Nutrición Hospitalaria , 2004,
Bloqueos miocárdicos periféricos no complicados y complicados
de Micheli, Alfredo;Medrano, Gustavo A.;Iturralde-Torres, Pedro;
Archivos de cardiología de México , 2009,
Abstract: septal necrosis + peripheral left blocks. because of an extensive septal necrosis, the manifestation of the initial ventricular activation forces decreases in the precordial leads. with left bifascicular block (lasb + lpsb), the first ventricular activation forces become more evident and the electrical signs of septal necrosis can be concealed. in the presence of a trifascicular block, the manifestation of the first ventricular electromotive forces diminishes again and the electrical signs of septal necrosis become evident once more. small q waves are present in leads v1 to v4. extensive anterior necrosis + left peripheral blocks. this necrosis is manifested by qs complexes from v2 to v6. an associated left bifascicular block reduces the electrical manifestation of dead tissue: qs complexes persist only in v3 and v4. in turn, a coexisting trifascicular block causes the presence of qs complexes from v2 to v5. posteroinferior necrosis + left peripheral blocks. electromotive forces of the ventricular activation shift upward, due to a posteroinferior necrosis, and qs or qr complexes are recorded in leads avf, ii and iii. an associated left bifascicular block displaces the main electromotive forces downward, posteriorly and to the left, due to a delay of the posteroinferior activation fronts. the ventricular complexes become positive and wider in all leads, reflecting the potential variations of the inferior portions of the left ventricle: avf, ii, iii, sometimes v5 and v6. consequently, the electrical signs of necrosis are reduced or abolished right ventricular peripheral blocks do not conceal the electrocardiographic signs of univentricular and biventricular dead myocardium.
Wormholes, Gamma Ray Bursts and the Amount of Negative Mass in the Universe
Diego F. Torres,Gustavo E. Romero,Luis A. Anchordoqui
Physics , 1998, DOI: 10.1142/S0217732398001650
Abstract: In this essay, we assume that negative mass objects can exist in the extragalactic space and analyze the consequences of their microlensing on light from distant Active Galactic Nuclei. We find that such events have very similar features to some observed Gamma Ray Bursts and use recent satellite data to set an upper bound to the amount of negative mass in the universe.
Might some gamma ray bursts be an observable signature of natural wormholes?
Diego F. Torres,Gustavo E. Romero,Luis A. Anchordoqui
Physics , 1998, DOI: 10.1103/PhysRevD.58.123001
Abstract: The extragalactic microlensing scenario for natural wormholes is examined. It is shown that the main features of wormhole lensing events upon the light of distant Active Galactic Nuclei (AGNs) are similar to some types of already observed Gamma Ray Bursts (GRBs). Using recent satellite data on GRBs, an upper limit to the negative mass density -- ${\cal O} (10^{-36})$ g cm$^{-3}$ -- under the form of wormhole-like objects is presented.
Notas historiográficas sobre los estudios de elites en la Argentina: Política, sociedad y economía en el siglo XX
Mellado,María Virginia;
Estudios de filosof?-a pr??ctica e historia de las ideas , 2008,
Abstract: during the past decades a deep renovation and expansion of studies on élites and leader groups in argentina have taken place. many investigations started using new tools from the social sciences, namely anthropology and sociology, evidencing a more complex understanding of economic, political and social phenomena. this quantitative and qualitative expansion of historical, sociological and anthropological investigations cannot be detached from the set of factors that permitted the consolidation of these disciplines after the coming of democracy during the last decades of the xx century. together with the issues posed by these advances, a broader and more complex image of reality can be sketched from the analysis of the leader groups. moreover, these studies raised new questions about poorly explored periods. for this reason we attempt to outline a map of recent studies on élites and to make a historiographical evaluation of those contributions seeking for tools and approaches. this search, though partial and fragmentary, points at the common ground shared by argentinean works and those of other countries, selecting a set of investigations on political, economical and social élites along the xx century.
Los trazos de la disgregación: el juicio político al Gobernador Martínez Baca (Mendoza, 1973-1974)
Mellado,María Virginia;
Quinto sol , 2009,
Abstract: this article goes through the modality of internal divisions that exhibited the peronism party from mendoza throughout general elections in 1973. when the elections were won by the peronist alberto martínez baca, a series of intern conflicts appeared in the winning party that damaged the state administration of public affaires. the internal struggle between the different sectors that makes up the peronism was solved with a political court judgment to the governor. this institutional solution differed from the ones taken in other provincial contexts. through the analysis of the arguments of the court judgment and the strategies of the defense and the prosecution, the article searches to restore the itinerary of mendocinian peronism, focusing in its heterogeneity of perspectives and points of view, and also approaching the diversity of actors and social sectors that had endorsed to the peronism project.
Antiarrhythmic and arrhythmogenic action of inosine in experimental ventricular tachyarrhythmias
de Micheli, Alfredo;Pastelín, Gustavo;Chávez Domínguez, Rafael;Iturralde Torres, Pedro;Medrano, Gustavo A;
Archivos de cardiología de México , 2009,
Abstract: objective: to study the possible action of inosine on experimental ventricular tachyarrhythmias. material and methods: we used 92 mongrel dogs weighing 13 kg-17 kg, anesthetized with 30 mg/kg sodium pentobarbital applied intravenously. myocardial lesions were induced by injecting 1ml-1.5 ml of 70% phenol in the free wall of the left ventricle. in 36 dogs, the ventricular arrhythmia (vt) was induced 30 min later with aconitine crystals inserted into the periphery of the damaged area; in 16, vt was due only to myocardial damage and in the other 13 vt was spontaneously originated. twenty-nine animals constituted the control group; no inosine was administered to them. the possible effects of inosine were studied in 63 animals. leads ii, avr or avl, right and left unipolar intraventricular leads and that on the wall of the superior vena cava were recorded under control conditions, once the myocardial damage had been induced, during the ventricular tachycardia, and following the injection of inosine. of the 63 inosine-treated animals; in 34, vt was due to aconitine; in 16, it was produced only by the myocardial damage and, in 13, vt was presented spontaneously. results: sinus rhythm was not reestablished in the animals of the control group. inosine reestablished the sinus rhythm in 26 of 34 dogs (76%) that received phenol and aconitine, in 13 of the 16 (81%) presenting only the myocardial damage, and in 6 of the 13 (46%) with spontaneous ventricular tachycardia. in some experiments, inosine induced supraventricular tachycardias, ventricular-atrial blocks, and ventricular pre-excitation phenomena. conclusions: in this experimental series, inosine showed antiarrhythmic and arrhythmogenic effects, similar to those of adenosine from which it derives.
Neutrinos from Accreting Neutron Stars
Luis A. Anchordoqui,Diego F. Torres,Thomas P. McCauley,Gustavo E. Romero,Felix A. Aharonian
Physics , 2002, DOI: 10.1086/374551
Abstract: The magnetospheres of accreting neutron stars develop electrostatic gaps with huge potential drops. Protons and ions, accelerated in these gaps along the dipolar magnetic field lines to energies greater than 100 TeV, can impact onto a surrounding accretion disc. A proton-induced cascade so develops, and $\nu$-emission is produced from charged pion decays. Using GEANT4, a computer code that tracks particles produced in high energy collisions, we have calculated the resulting $\nu$-spectrum with extensive disc shower simulations. We show that the $\nu$-spectrum produced out of the proton beam is a power law. We use this result to propose accretion-powered X-ray binaries (with highly magnetized neutron stars) as a new population of point-like $\nu$-sources for km-scale detectors, such as ICECUBE. As a particular example we discuss the case of A0535+26. We show that ICECUBE should find A0535+26 to be a periodic $\nu$-source: one for which the formation and loss of its accretion disc can be fully detected. Finally, we briefly comment on the possibility that smaller telescopes, like AMANDA, could also detect A0535+26 by folding observations with the orbital period.
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