Descripción: We present radio observations of the source G332.5-5.6, a candidate supernova remnant (SNR). Observations have been performed with the Australia Telescope Compact Array (ATCA) at two frequencies, 1.4 and 2.4 GHz. Our results confirm that G332.5-5.6 is an SNR, with a spectral index α = -0.7 ± 0.2 for the whole source and an average fractional polarization of ∼35 per cent at 2.4 GHz. The central component is coincident with extended X-ray emission, and the distance to the SNR is estimated to be ∼3.4 kpc. Based on its radio and X-ray morphology, this SNR should be classified as a composite, and we suggest that it belongs to a trident-shaped subclass like G291.0-0.1. © 2006 RAS.

Descripción: Sudden Galactic Cosmic Ray (GCR) intensity decreases are related to the passage of Interplanetary Coronal Mass Ejections (ICMEs). These phenomena are also known as Forbush Decreases (FDs). The deepest FDs are associated with the passage of Magnetic Clouds (MCs). In this preliminary study we select "non-interacting" MCs associated with FDs observed from ground Neutron Monitors in the period 1996-2009, with the aim of reducing the complexity and the number of parameters involved in the GCR-MC interactions. We introduce a method to determine properties of the "ejecta component" of the FD. We analyze properties of the ejecta component in combination with properties of MCs. From the resulting selection of events, we find that those FDs containing ejecta components show stronger correlations with MC parameters than our total sample of events. © 2013 International Astronomical Union.

Descripción: Galectin-1 (Gal-1) is a widely expressed β-galactoside-binding protein that exerts pleiotropic biological functions. To gain insight into the potential role of Gal-1 as a novel modulator of Leydig cells, we investigated its effect on the growth and death of MA-10 tumor Leydig cells. In this study, we identified cytoplasmic Gal-1 expression in these tumor cells by cytofluorometry. DNA fragmentation, caspase-3, -8, and -9 activation, loss of mitochondrial membrane potential (ΔΨ m), cytochrome c (Cyt c) release, and FasL expression suggested that relatively high concentrations of exogenously added recombinant Gal-1 (rGal-1) induced apoptosis by the mitochondrial and death receptor pathways. These pathways were independently activated, as the presence of the inhibitor of caspase-8 or -9 only partially prevented Gal-1-effect. On the contrary, low concentrations of Gal-1 significantly promoted cell proliferation, without inducing cell death. Importantly, the presence of the disaccharide lactose prevented Gal-1 effects, suggesting the involvement of the carbohydrate recognition domain (CRD). This study provides strong evidence that Gal-1 is a novel biphasic regulator of Leydig tumor cell number, suggesting a novel role for Gal-1 in the reproductive physiopathology. © Copyright 2006 Oxford University Press.

Descripción: Galectins control critical pathophysiological processes, including the progression and resolution of central nervous system (CNS) inflammation. In spite of considerable progress in dissecting their role within lymphoid organs, their functions within the inflamed CNS remain elusive. Here, we investigated the role of galectin-glycan interactions in the control of oligodendrocyte (OLG) differentiation, myelin integrity and function. Both galectin-1 and-3 were abundant in astrocytes and microglia. Although galectin-1 was abundant in immature but not in differentiated OLGs, galectin-3 was upregulated during OLG differentiation. Biochemical analysis revealed increased activity of metalloproteinases responsible for cleaving galectin-3 during OLG differentiation and modulating its biological activity. Exposure to galectin-3 promoted OLG differentiation in a dose-and carbohydrate-dependent fashion consistent with the glycosylation signature of immature versus differentiated OLG. Accordingly, conditioned media from galectin-3-expressing, but not galectin-3-deficient (Lgals3/) microglia, successfully promoted OLG differentiation. Supporting these findings, morphometric analysis showed a significant decrease in the frequency of myelinated axons, myelin turns (lamellae) and g-ratio in the corpus callosum and striatum of Lgals3/compared with wild-type (WT) mice. Moreover, the myelin structure was loosely wrapped around the axons and less smooth in Lgals3/mice versus WT mice. Behavior analysis revealed decreased anxiety in Lgals3/mice similar to that observed during early demyelination induced by cuprizone intoxication. Finally, commitment toward the oligodendroglial fate was favored in neurospheres isolated from WT but not Lgals3/mice. Hence, glial-derived galectin-3, but not galectin-1, promotes OLG differentiation, thus contributing to myelin integrity and function with critical implications in the recovery of inflammatory demyelinating disorders. © 2011 Macmillan Publishers Limited All rights reserved.

Descripción: Adelomelon beckii (Broderip, 1836) (Neogastropoda: Volutidae) is endemic to the western south Atlantic coast. It inhabits sandy bottoms in waters between 40 and 70 m deep and is one of the largest top benthic predators found in Mar del Plata, Argentina. The present study describes gametogenesis and the reproductive cycle of this species. Oocytes developed in close association with follicle cells, which appear to play a role in yolk synthesis and oocyte resorption, providing the key functions of phagocytosis and intracellular digestion of degenerating oocytes. Spermatogenesis resembles that reported for other volutids. The reproductive cycle of A. beckii in Mar del Plata was studied over a period of 2 yr (September 2004 to August 2006). Gametic emission in males continued throughout the year while females showed 2 spawning periods: one during spring (September-November) and another during autumn (March-April). In females, this semi-annual pattern appears to be related to the seasonal variation in seawater temperature, coinciding with observations made in other volutes. In males, there was no relationship to variation in seawater temperature, an unusual pattern for a species from a temperate region. Imposex was described for the first time in this species. These data constitute baseline information for establishing appropriate and biologically based management and conservation strategies for this overexploited gastropod species. © Inter-Research 2010.

Descripción: A new species, Geastrum episcopale, is described from Argentina. Detailed descriptions and illustrations of fresh and dry basidiomata are provided along with photographs of microscopic elements, such as spores, capillitium, calcium oxalate crystals, and exo- and endoperidium surfaces. This fungus is typical of the genus in its morphology and ecology but clearly differs from every known species. This species can be distinguished easily by the red-violet (to magenta) exoperidium and the lilac endoperidium. Specimens were collected on wet soil composed of a superficial layer of ca. 5 cm leaf litter and 15 cm of particulate and melanized lignocellulosic material (pH 6.5) under Eugenia uruguayensis and Nectandra sp. © 2009 by The Mycological Society of American.

Descripción: A survey of Geastrum species from arid lands in the La Rioja province (northwestern Argentina) recovered fourteen species previously unreported from the province: G. arenarium, G. campestre var. famatinum, G. corollinum, G. fimbriatum, G. floriforme, G. glaucescens, G. hieronymi, G. aff. lloydianum, G. pampeanum, G. pampeanum var. pallidum, G. parvistriatum, G. rufescens, G. saccatum, and G. schmidelii. Of these, new records are G. corollinum for Argentina, G. arenarium for South America, and G. parvistriatum for the Americas, and G. campestre var. famatinum is proposed as a new variety. Each taxon is described, and photographs of basidiomes and SEM micrographs illustrating spores are provided for selected taxa. © 2012. Mycotaxon, Ltd.

Descripción: Understanding the genetic architecture of any quantitative trait requires identifying the genes involved in its expression in different environmental conditions. This goal can be achieved by mutagenesis screens in genetically tractable model organisms such as Drosophila melanogaster. Temperature during ontogenesis is an important environmental factor affecting development and phenotypic variation in holometabolous insects. In spite of the importance of phenotypic plasticity and genotype by environment interaction (GEI) for fitness related traits, its genetic basis has remained elusive. In this context, we analyzed five different adult morphological traits (face width, head width, thorax length, wing size and wing shape) in 42 co-isogenic single P-element insertional lines of Drosophila melanogaster raised at 17°C and 25°C. Our analyses showed that all lines differed from the control for at least one trait in males or females at either temperature. However, no line showed those differences for all traits in both sexes and temperatures simultaneously. In this sense, the most pleiotropic candidate genes were CG34460, Lsd-2 and Spn. Our analyses also revealed extensive genetic variation for all the characters mostly indicated by strong GEIs. Further, our results indicate that GEIs were predominantly explained by changes in ranking order in all cases suggesting that a moderate number of genes are involved in the expression of each character at both temperatures. Most lines displayed a plastic response for at least one trait in either sex. In this regard, P-element insertions affecting plasticity of a large number of traits were associated to the candidate genes Btk29A, CG43340, Drak and jim. Further studies will help to elucidate the relevance of these genes on the morphogenesis of different body structures in natural populations of D. melanogaster. © 2013 Carreira et al.

Descripción: Let Θ be a set of real numbers unbounded on both sides and let B be a finite set of positive integers. We characterize the entire functions that can be uniformly approximated on bounded sets by polynomials of the form ∏j∈Bpj(zj), where each pj(z) is a polynomial with zeros in Θ. © 1999 Academic Press.

Descripción: Let V be a closed algebraic subvariety of the n-dimensional projective space over the complex or real numbers and suppose that V is non-empty and equidimensional. The classic notion of a polar variety of V associated with a given linear subvariety of the ambient space of V was generalized and motivated in Bank et al. (Kybernetika 40 (2004), to appear). As particular instances of this notion of a generalized polar variety one reobtains the classic one and an alternative type of a polar variety, called dual. As main result of the present paper we show that for a generic choice of their parameters the generalized polar varieties of V are empty or equidimensional and smooth in any regular point of V. In the case that the variety V is affine and smooth and has a complete intersection ideal of definition, we are able, for a generic parameter choice, to describe locally the generalized polar varieties of V by explicit equations. Finally, we indicate how this description may be used in order to design in the context of algorithmic elimination theory a highly efficient, probabilistic elimination procedure for the following task: In case, that the variety V is ℚ-definable and affine, having a complete intersection ideal of definition, and that the real trace of V is non-empty and smooth, find for each connected component of the real trace of V an algebraic sample point. © 2005 Elsevier Inc. All rights reserved.

Descripción: We prove the existence of Lpfunctions satisfying a kind of self-similarity condition. This is achieved by solving a functional equation by means of the construction of a contractive operator on an appropriate functional space. The solution, a fixed point of the operator, can be obtained by an iterative process, making this model very suitable to use in applications such as fractal image and signal compression. On the other hand, this "generalized self-similarity equation" includes matrix refinement equations of the typef(x)=∑ckf(Ax-k) which are central in the construction of wavelets and multiwavelets. The results of this paper will therefore yield conditions for the existence of Lp-refinable functions in a very general setting. © 1998 Academic Press.

Descripción: The common principal components (CPC) model for several groups of multivariate observations assumes equal principal axes but possibly different variances along these axes among the groups. Under a CPCs model, generalized projection-pursuit estimators are defined by using score functions on the dispersion measure considered. Their partial influence functions are obtained and asymptotic variances are derived from them. When the score function is taken equal to the logarithm, it is shown that, under a proportionality model, the eigenvector estimators are optimal in the sense of minimizing the asymptotic variance of the eigenvectors, for a given scale measure. © 2004 Elsevier Inc. All rights reserved.

Descripción: In this paper, the convergence criteria given by Stanton [J. Chem. Phys. 75, 5416 (1981)] for the Hartree-Fock SCF calculations of closed-shell systems are generalized for an unrestricted one-determinantal Hartree-Fock SCF calculation. Finally, these criteria are related to the stability conditions of the Hartree-Fock wave functions. © 1983 American Institute of Physics.

Descripción: Let Zv t, z be a ℝd-valued jump diffusion controlled by v with initial condition Zv t, z(t) = z. The aim of this paper is to characterize the set V (t) of initial conditions z such that Zv t, z can be driven into a given target at a given time by proving that the function u(, z) = 1 − 1V(t) satisfies, in the viscosity sense, the equation (2) below. As an application, we study the problem of hedging in a financial market with a large investor. © 2007 Applied Probability Trust.

Descripción: Addition of affinity tags to bacteriophage particles facilitates a variety of applications, including vaccine construction and diagnosis of bacterial infections. Addition of tags to phage capsids is desirable, as modification of the tails can lead to poor adsorption and loss of infectivity. Although tags can readily be included as fusions to head decoration proteins, many phages do not have decoration proteins as virion components. The addition of a small (10-amino-acid) Strep-tag II (STAG II) to the mycobacteriophage TM4 capsid subunit, gp9, was not tolerated as a genetically homogenous recombinant phage but could be incorporated into the head by growth of wild-type phage on a host expressing the capsid-STAG fusion. Particles with capsids composed of wild-type and STAG-tagged subunit mixtures could be grown to high titers, showed good infectivities, and could be used to isolate phage-bacterium complexes. Preparation of a STAG-labeled fluoromycobacteriophage enabled capture of bacterial complexes and identification of infected bacteria by fluorescence. © 2013, American Society for Microbiology.

Descripción: By taking advantage of the extreme stability of a protein-DNA complex, we have obtained two highly specific monoclonal antibodies against a predetermined palindromic DNA sequence corresponding to the binding site of the E2 transcriptional regulator of the human papillomavirus (HPV-16). The purified univalent antibody fragments bind to a double-stranded DNA oligonucleotide corresponding to the E2 binding site in solution with dissociation constants in the low and subnanomolar range. This affinity matches that of the natural DNA binding domain and is severalfold higher than the affinity of a homologous bovine E2 C-terminal domain (BPV-1) for the same DNA. These antibodies discriminate effectively among a number of double- and single-stranded synthetic DNAs with factors ranging from 125-to 20,000-fold the dissociation constant of the specific DNA sequence used in the immunogenic protein-DNA complex. Moreover, they are capable of fine specificity tuning, since they both bind less tightly to another HPV-16 E2 binding site, differing in only 1 base pair in a noncontact flexible region. Beyond the relevance of obtaining a specific anti-DNA response, these results provide a first glance at how DNA as an antigen is recognized specifically by an antibody. The accuracy of the spectroscopic method used for the binding analysis suggests that a detailed mechanistic analysis is attainable.

Descripción: Glucocorticoids are potent regulators of the innate immune response, and alteration in this inhibitory feedback has detrimental consequences for the neural tissue. This study profiled and investigated functionally candidate genes mediating this switch between cell survival and death during an acute inflammatory reaction subsequent to the absence of glucocorticoid signaling. Oligonucleotide microarray analysis revealed that following lipopolysaccharide (LPS) intracerebral administration at striatum level, more modulated genes presented transcription impairment than exacerbation upon glucocorticoid receptor blockage. Among impaired genes we identified ceruloplasmin (Cp), which plays a key role in iron metabolism and is implicated in a neurodegenative disease. Microglial and endothelial induction of Cp is a natural neuroprotective mechanism during inflammation, because Cp-deficient mice exhibited increased iron accumulation and demyelination when exposed to LPS and neurovascular reactivity to pneumococcal meningitis. This study has identified genes that can play a critical role in programming the innate immune response, helping to clarify the mechanisms leading to protection or damage during inflammatory conditions in the CNS. © 2007 Glezer et al.

Descripción: Soil-landscape relationships were studied in the central region of Santa Cruz, southern Argentina, between 49-51°S on the Atlantic coast westward to the international border with Chile. Two different sectors were distinguished. The western area, including the Patagonian Andean Cordillera and piedmont is characterised by strong landscape variations, a udic-xeric humidity regime and Nothofagus woodlands; the eastern area has an arid regime, grassland-shrub steppe and large flat structural plain landscape. As a result of the different landscape-relief features and parent materials, the two areas have different soils associations. The western area is characterised by an Andisol-Mollisol-Entisol sequence, whereas the eastern area has an Ardidisol-Entisol trend. The principal characteristics and properties of the soils are analysed and discussed in relation to variations in the conditions of formation.

Descripción: El Infiernillo Mining District is located in the San Rafael Block (34°38'20";68°47'37"), province of Mendoza, Argentina. It is a porphyry Cu (Mo) type deposit which is hosted by a volcaniclastic sequence. It develops an alteration halo with a concentric pattern consisting of a central quartz neck surrounded by a potassic alteration zone and outwards a phyllic halo and small polymetallic veins. The potassic halo has a paragenesis of K-feldspar-quartz-(biotite). Three silicification phases are related to this alteration stage, one of them (with temperature between 550° and 390°C and salinity between 35 and 47 %) genetically linked to the copper mineralization. The phyllic alteration consists of quartz-illite-(rutile) with minor albite. The albitization process points out to an early phase of this phyllic stage. The fluid inclusions together with the textures of the quartz neck suggest the shallowing of the active hydrothermal system. The disseminated ore paragenesis consists of bornite, chalcopyrite-molibdenite, pyrite, (galena-sphalerite). The presence of molibdenite-quartz veins indicate the transition from the potassic to the phyllic stage while the pyrite-quartz ones point out to a transition to a fragile deformation regime during which the polymetallic veins, with a paragenesis of chalcopyrite- sphalerite, pyrite, (Ag) tetrahedrite, galena were formed. The petrologic characteristics of the volcaniclastic host rocks reveal that they correspond to the lower section of Choiyoi magmatic cycle. The magmatic and structural controls constrain the age of this ore deposit to the Early-Middle to Late Permian.

Descripción: Background: A partial deficiency in Protoporphyrinogen oxidase (PPOX) produces the mixed disorder Variegate Porphyria (VP), the second acute porphyria more frequent in Argentina. Identification of patients with an overt VP is absolutely important because treatment depends on an accurate diagnosis but more critical is the identification of asymptomatic relatives to avoid acute attacks which may progress to death. Methods: We have studied at molecular level 18 new Argentinean patients biochemically diagnosed as VP. PPOX gene was amplified in one or in twelve PCR reactions. All coding exons, flanking intronic and promoter regions were manual or automatically sequenced. For RT-PCR studies RNA was retrotranscripted, amplified and sequenced. PPOX activity in those families carrying a new and uncharacterized mutation was performed. Results: All affected individuals harboured mutations in heterozygous state. Nine novel mutations and 3 already reported mutations were identified. Six of the novel mutations were single nucleotide substitutions, 2 were small deletions and one a small insertion. Three single nucleotide substitutions and the insertion were at exon-intron boundaries. Two of the single nucleotide substitutions, c.471G>A and c.807G>A and the insertion (c.388+3insT) were close to the splice donor sites in exons 5, 7 and intron 4 respectively. The other single nucleotide substitution was a transversion in the last base of intron 7, g.3912G>C (c.808-1G>C) so altering the consensus acceptor splice site. However, only in the first case the abnormal band showing the skipping of exon 5 was detected. The other single nucleotide substitutions were transversions: c.101A>T, c.995G>C and c.670 T>G that result in p.E34V, p.G332A and W224G aminoacid substitutions in exons 3, 10 and 7 respectively. Activity measurements indicate that these mutations reduced about 50% PPOX activity and also that they co-segregate with this reduced activity value. Two frameshift mutations, c.133delT and c.925delA, were detected in exons 3 and 9 respectively. The first leads to an early termination signal 22 codons downstream (p.S45fsX67) and the second leads to a stop codon 5 codons downstream (p.I309fsX314). One reported mutation was a missense mutation (p.G232R) and 2 were frameshift mutations: c.1082insC and 1043insT. The last mutation was detected in six new apparently unrelated Argentinean families. Conclusion: Molecular analysis in available family members revealed 14 individuals who were silent carriers of VP. Molecular techniques represent the most accurate approach to identify unaffected carriers and to provide accurate genetic counselling for asymptomatic individuals. The initial screening includes the insertion search. © 2008 Rossetti et al; licensee BioMed Central Ltd.

Descripción: Phytophthora sojae causes root and stem rot, one of the most important diseases of soybean worldwide. Genetic diversity of 32 Phytophthora sojae isolates of different geographic origin from Argentina was evaluated with RAPD markers. The isolates were collected from diseased soybean plants and soil samples from Santa Fe, Buenos Aires, Córdoba and Entre Ríos provinces, in the Pampeana Region. DNA was amplified with 20 decanucleotides primers. Seven primers amplified 49 fragments, of which 35 were polymorphic, indicating high variability. RAPD analysis detected intraspecific variability even among isolates of the same geographic origin. © 2007 by The Mycological Society of America.

Descripción: The high-altitude Andean lakes (HAAL) in the Argentinean Puna-high Andes region represent an almost unexplored ecosystem exposed to extreme conditions (high UV irradiation, hypersalinity, drastic temperature changes, desiccation, and high pH). Here we present the first genome sequence, a Sphingomonas sp., isolated from this extreme environment. © 2011, American Society for Microbiology.

Descripción: Fil:Poggio, L. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.

Descripción: Twenty-one native populations (1120 individuals) of maize from Northern Argentina were studied. These populations, which belong to 13 native races were cultivated at different altitudes (80-3620 m). Nineteen of the populations analyzed showed B chromosome (Bs) numerical, polymorphism. The frequency of individuals with Bs varied from 0 to 94%. The number of Bs per plant varied from 0 to 8 Bs, with the predominant doses being 0, 1, 2, and 3. Those populations with varying number of Bs showed a positive and statistically significant correlation of mean number of Bs with altitude. The DNA content, in plants without Bs (A-DNA)(2n = 20), of 17 populations of the 21 studied was determined. A 36% variation (5.0-6.8 pg) in A-DNA content was found. A significant negative correlation between A-DNA content and altitude of cultivation and between A-DNA content and mean number of Bs was found. This indicates that there is a close interrelationship between the DNA content of A chromosomes and doses of Bs. These results suggest that there is a maximum limit to the mass of nuclear DNA so that Bs are tolerated as long as this maximum limit is not exceeded.

Descripción: Fil:Ramírez-Llorens, P. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.

Descripción: A new record for the Argentinean flora, Samanea tubulosa, is described and illustrated. The specimens were collected in Oran, Salta Province, Argentina, in the "Selvas Pedemontanas" district of the "Yungas" phytogeographic province. Comments on the systematic position of the species and related genera are given.

Descripción: Landforms and soils in the Traful River Valley, Neuquén Province. The Andes Patagónicos Region is characterised by the presence of strong west-east bioclimatic, geomorphological and lithostratigraphical gradients, that controlled the genesis and geographical distribution of soils. In this contribution soil-landscape relationships in a sector of a transitional zone in the northern Andes Patagónicos are studied. The Traful River valley is located in Neuquén Province aproximately at 40°40′S and 71°15′W. Diverse geomorphological units were distinguished which were formed through glacial and fluvioglacial action, and partially modified in recent times by fluvial and eolian processes and by mass wasting. Holocen ashes and lapilli were deposited in different volcanic events and constitute the soils'main parent material. We recognize soils belong to three orders: entisols, mollisols and andisols. A strong gradient of variations in soils properties was observed. The Andisolization process decrease with distance from the Cordillera zone. © 1999 Asociación Geológica Argentina.

Descripción: The inversion polymorphisms of the cactophilic Drosophila buzzatti Patterson and Wheeler (Diptera: Drosophilidae) were studied in new areas of its distribution in Argentina. A total of thirty-eight natural populations, including 29 from previous studies, were analyzed using multiple regression analyses. The results showed that about 23% of total variation was accounted for by a multiple regression model in which only altitude contributed significantly to population variation, despite the fact that latitude and longitude were also included in the model. Also, inversion frequencies exhibited significant associations with mean annual temperature, precipitation, and atmospheric pressure. In addition, expected heterozygosity exhibited a negative association with temperature and precipitation and a positive association with atmospheric pressure. The close similarity of the patterns detected in this larger dataset to previous reports is an indication of the stability of the clines. Also, the concurrence of the clines detected in Argentina with those reported for colonizing populations of Australia suggests the involvement of natural selection as the main mechanism shaping inversion frequencies in D. buzzatii.

Descripción: The geomagnetic field (B geo) sets a lower cutoff rigidity (R c) to the entry of cosmic particles to Earth which depends on the geomagnetic activity. From numerical simulations of the trajectory of a proton (performed with the MAGCOS code) in the B geo, we use backtracking to analyze particles arriving at the Auger Observatory location. We determine the asymptotic trajectories and the values of R c in different incidence directions. Simulations were done using several models of B geo that emulate different geomagnetic conditions. © 2012 International Astronomical Union.

Descripción: We develop the homology theory of CW (A)-complexes, generalizing the classical cellular homology theory for CW-complexes. A CW (A)-complex is a topological space which is built up out of cells of a certain core A. © 2008 Elsevier B.V. All rights reserved.

Descripción: This paper deals with the index reduction problem for the class of quasi-regular DAE systems. It is shown that any of these systems can be transformed to a generically equivalent first order DAE system consisting of a single purely algebraic (polynomial) equation plus an under-determined ODE (a differential Kronecker representation) in as many variables as the order of the input system. This can be done by means of a Kronecker-type algorithm with bounded complexity. © 2011 Elsevier Ltd.

Descripción: The main geomorphological features of a sector of Sierras Australes (Buenos Aires province) are described. Fluvial processes (mainly formation of alluvial fans), mass wasting (creep and debrisflows) and wind action (deflation and acumulation) are responsible for the configuration of the landscape of the region. At least three alluvial acumulation events and equal number of loess deposition were recognized for the late Cenozoic times. The development of a planation surface of pre-Cenozoic age, and developed in Palaeozoic rocks, is postulated. This surface and the piedmont acumulations were affected by erosional events related to tectonic, climatic and eustatic events (Andean Orogeny and glaciations). Six major geomorphological units are recognized. Today the pedogenetic processes predominate whereas morphodynamic ones are low.

Descripción: An ancient alluvial fan and its subsequent evolution are described. Ancient alluvial fan accumulations have been interpreted as the northern continuation of the rodados patagónicos of the Montemayor Plateau, a proposal that is contested. The methodological recognition of the ancient alluvial fan and its genetic and temporary distinction, were made from geomorphologic analysis and altimetric evaluation. Time assignment is a problem not yet solved. The methodology led to three different geomorphic systems or levels related to successive episodes of aggradation and erosion, with increasing lower positions, which coincide with a complex paleodrainage ancient alluvial fan. its successive developments are linked to proposed proto-rivers Chubut 1, 2, 3 and to a Simpson paleo-valley. Despite the mentioned limitations, we propose that the evolutionary model of ancient alluvial fan responds to a structure of cut and fill which is supported by the poly-formational composition of an ancient alluvial fan, and a gradual southward migration of the paleo-drainage. Based on geomorphologic analysis and altimetric distinction an upper level, composed of the remains of three plains (Pa, Pm and Pb), a middle level with two terraces (T1 and T2) and a complex lower level and five terraces (T3, T4, T5 T6 and T7) were recognized. Relict evidences of paleo-drainages are proposed based on the Estancia Paz and Don Morgan-Saraza paleo-valleys in the upper level. The age of the ancient alluvial fan based on the geomorphic evolution of the study area is tentatively assigned to an uncertain period between the late Pleistocene and late Sangamon interglacial at the end of the last glaciation.

Descripción: The geomorphologic analysis of the study area led to distinguish some formations not considered in previous geological research, as well as to explain the characteristics of the present relief. Thirteen principal geomorphic units produced by different geomorphic processes are recognized. Their variety and incidence through the time are expressed in the glacial morphogenesis concentrated in the western part of the Cordillera del Viento, in the volcanic landscape that predominates in the northern and eastern sectors (calderas, volcanoes, lava flows), in the structural control that defines the morphology of the fluvial process in the central zone and a firstly recognized important landslide to the north of Tricao Malal. As a result of the methodology employed two geological units of different age in the western part of the Tromen-Waile volcanic field were distinguished, which were initially interpreted as a single formation. A limited but consistent structural analysis of the region is also included.

Descripción: This thematic map describes the principal features of the landscape, a relative sequence of its geomorphic evolution, and arrives to important conclusions about its regional stratigrapby. The regional landscape is composed and polycyclic. The geoforms are related to different exogenous processes (glacial, fluvial and mass-wasting). An endogenous process (volcanism) formed the more distinctive features; a great tectonic-volcanic caldera and the preglacial Copahue stratovolcano. Some minor and youngest volcanic forms were formed during postglacial times. A previous fluvial cycle was replaced by glacial morphogenesis (valley glaciation) during the Quaternary, due a climatic intervention. A huge and very thick (500-800 m) ice-blister was lodged into the caldera. The ice-blister exceded the caldera's edges forming several glacial diffluences and giving an important and additional supply to neighbouring glacial valleys (Hualcupén and Trocoman), out of to the depression. The Pleistocene glaciation shows two local cycles of volcanic eruptions: pre- and post-glacial. The origin of many local lakes was related to glacial exharation. Others lakes have different genesis: by blocking slide, crater-lake and glacial exharation associated with important structural weakness (Caviahue Lake related to the Trapa-Trapa lineament or Caviahue graben). During postglacial times important rock-avalanches occurred in the Hualcupén valley: the Cajón Chico and Compul rock-avalanches were related to seismic shocks. Previously, their accumulations were interpreted as terminal moraines of a second glaciation. A fluvial rejuvenation phase was the consequence of a blocking of Agrio River by the Agrio volcanic flows, during the Holocene. After that, the river eroded this obstacle restablishing its previous base level. The Agrio cascade represents the upstream present position of the consequent rejuvenation wave. © 2005 Asociación Geológica Argentina.

Descripción: The region is situated in the Neuquén Cordillera at 38° 30'S latitud close to the international border. Geomorphic and structural features are presented which indicated a glacial morphogenesis for the depression that contains the Moquehue- Aluminé lakes. Previous works have identified a large volcanic complex related to Plio-Quaternary volcanic activity located at the east of the present volcanic arc. In this sector various caldera depressions and associated domic bodies have been identified. From the nine proposed calderas only the Pino Hachado caldera has been studied in detail. The Meseta del Arco and Nacimientos del Aluminé are disregarded as calderas. The erosional genesis of the steep scarps previously interpreted as caldera margins is also identified with glacial erosion. Facies and types of the local Pleistocene glaciation, its extension, their flow direction and its quite probable diffluence (Paso del Arco) through coeval glaciers situated north of the international border are also analyzed. Local characteristics of volcanic and eolian morphogenic and the mass-wasting process are described. Brief comments about pre-glacial drainage and the previous proposal of Bío Bío-Aluminé trough on the region are added. Transversal topographic-geological profiles discard west of the Bío Bío-Aluminé Fault a structural unit related to tectonic depression of Bío Bío-Aluminé trough and the Nacimientos del Aluminé and Moquehue calderas.

Descripción: We report high magnetic field magnetostructural studies on Gd 2/3Ca1/3MnO3 single crystals. A giant linear magnetostrictive effect is observed in a wide temperature range (T < 120 K). Above 25 K a large hysteresis is seen reflecting the Mn magnetic moments ordering. At lower temperature (T < 15 K), a rather complicated field dependence arising from the competition between the Mn and Gd magnetic sublattices is observed. The relevance of the Gd ions in the low temperature behavior is further corroborated by specific heat experiments. © 2009 IOP Publishing Ltd.

Descripción: Fil:Ferrari, P.A. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.

Descripción: This paper studies the classical propagator on Glauber's coherent states in a generalized P-form. A full class of equivalent expressions labeled by a complex number is found through a direct WKB expansion. The study of matrix elements of the propagator between coherent states shows that they match Klauder's classical expression but are in some disagreement in the semiclassical order with expression derived through path integral procedures. Arguments are given that favor the present results. The properties of the time propagator with respect to symmetry operations are stated. Possible extensions are briefly discussed. © 1986 American Institute of Physics.

Descripción: The Maastrichtian-Early Palaeocene Salamanca Formation and equivalent marine sequences show several glaucony levels, which could be used as a source of potassium and could partially replace current fertilizer requirements met from import. First agronomic assays are shown comparing the efficiency of greensands (GL) with a traditional potassium fertilizer (KCl). Prospection and sampling took place in the heads of Rio Chico to east of Lago Colhué Huapi, Chubut, where glauconitic levels thickness reach to 20m. This research was separated in phases: phase 1, prospection, sampling, and sedimentological and chemical routine analyses, phase 2a, concentration and ore treatment assays, and phase 2b, agronomic assays. This last phase, was done in culture chamber, with 125 μm and 250 μm fractions (2,85 and 2,82 % K 2 O respectively) and KCl. Varying the dose, seven treatments were completed. In successive harvests (four in total) was observed that GL1 and GL2 (125), did not present a significantly differential behavior with the control. Both treatments of GL 250 μm showed major accumulated biomass, overcoming the control in 44 and 60 % respectively. As conclusion, better results were obtained by 250 μm overcoming even to the KCl fertilization. Probably the major participation of K feldspars in the 125 μm and fast leaching of K in this fraction during successive irrigations of soil would originate the minor observed yield. The great areal extension of the Salamanca Formation and the continuity of the glauconitic levels encourage continuing the evaluation as fertilizer or amendment.

Descripción: Two fossil tadpoles collected in the Deseadan levels (Oligocene) at the Scarritt Pocket locality of central Patagonia are studied herein. These specimens, which show different degrees of skeletal development, have been assigned to the neobatrachian Calyptocephalella canqueli based on the morphology of the frontoparietals and the presence of adult specimens of this fossil species at the same locality. The concurrent analysis of three developmental stages (Gosner Stages 35/36 and 38/39, and adult) has provided significant data about the ontogeny of this species, including the change of the pattern of exostosis of the frontoparietals, from a pitted to a tuberculated pattern, and the corroboration of the inclusion of two neural arches in the formation of the urostyle. This evidence will shed light on developmental mechanisms that might be involved in the evolution of the genus Callyptocephalella.

Descripción: Fragmentation functions for eta mesons are extracted at next-to-leading order accuracy of QCD in a global analysis of data taken in electron-positron annihilation and proton-proton scattering experiments. The obtained parametrization is in good agreement with all data sets analyzed and can be utilized, for instance, in future studies of double-spin asymmetries for single-inclusive eta production. The Lagrange multiplier technique is used to estimate the uncertainties of the fragmentation functions and to assess the role of the different data sets in constraining them. © 2011 American Physical Society.

Descripción: We present a new global QCD analysis of nuclear parton distribution functions and their uncertainties. In addition to the most commonly analyzed data sets for the deep-inelastic scattering of charged leptons off nuclei and Drell-Yan dilepton production, we include also measurements for neutrino-nucleus scattering and inclusive pion production in deuteron-gold collisions. The analysis is performed at next-to-leading order accuracy in perturbative QCD in a general mass variable flavor number scheme, adopting a current set of free nucleon parton distribution functions, defined accordingly, as reference. The emerging picture is one of consistency, where universal nuclear modification factors for each parton flavor reproduce the main features of all data without any significant tension among the different sets. We use the Hessian method to estimate the uncertainties of the obtained nuclear modification factors and examine critically their range of validity in view of the sparse kinematic coverage of the present data. We briefly present several applications of our nuclear parton densities in hard nuclear reactions at BNL-RHIC, CERN-LHC, and a future electron-ion collider. © 2012 American Physical Society.

Descripción: Context: Observations of magnetic clouds (MCs) are consistent with the presence of flux ropes detected in the solar wind (SW) a few days after their expulsion from the Sun as coronal mass ejections (CMEs). Aims: Both the in situ observations of plasma velocity profiles and the increase of their size with solar distance show that MCs are typically expanding structures. The aim of this work is to derive the expansion properties of MCs in the inner heliosphere from 0.3 to 1 AU. Methods: We analyze MCs observed by the two Helios spacecraft using in situ magnetic field and velocity measurements. We split the sample in two subsets: those MCs with a velocity profile that is significantly perturbed from the expected linear profile and those that are not. From the slope of the in situ measured bulk velocity along the Sun-Earth direction, we compute an expansion speed with respect to the cloud center for each of the analyzed MCs. Results: We analyze how the expansion speed depends on the MC size, the translation velocity, and the heliocentric distance, finding that allMCs in the subset of non-perturbed MCs expand with almost the same non-dimensional expansion rate (ζ).We find departures from this general rule for ζ only for perturbed MCs, and we interpret the departures as the consequence of a local and strong SW perturbation by SW fast streams, affecting the MC even inside its interior, in addition to the direct interaction region between the SW and the MC. We also compute the dependence of the mean total SW pressure on the solar distance and we confirm that the decrease of the total SW pressure with distance is the main origin of the observed MC expansion rate. We found that ζ was 0.91 ± 0.23 for non-perturbed MCs while ζ was 0.48 ± 0.79 for perturbed MCs, the larger spread in the last ones being due to the influence of the solar wind local environment conditions on the expansion. © ESO 2010.

Descripción: Context. Coronal mass ejections (CMEs) are routinely tracked with imagers in the interplanetary space, while magnetic clouds (MCs) properties are measured locally by spacecraft. However, both imager and in situ data do not provide any direct estimation of the general flux rope properties. Aims. The main aim of this study is to constrain the global shape of the flux rope axis from local measurements and to compare the results from in-situ data with imager observations. Methods. We performed a statistical analysis of the set of MCs observed by WIND spacecraft over 15 years in the vicinity of Earth. We analyzed the correlation between different MC parameters and studied the statistical distributions of the angles defining the local axis orientation. With the hypothesis of having a sample of MCs with a uniform distribution of spacecraft crossing along their axis, we show that a mean axis shape can be derived from the distribution of the axis orientation. As a complement, while heliospheric imagers do not typically observe MCs but only their sheath region, we analyze one event where the flux rope axis can be estimated from the STEREO imagers. Results. From the analysis of a set of theoretical models, we show that the distribution of the local axis orientation is strongly affected by the overall axis shape. Next, we derive the mean axis shape from the integration of the observed orientation distribution. This shape is robust because it is mostly determined from the overall shape of the distribution. Moreover, we find no dependence on the flux rope inclination on the ecliptic. Finally, the derived shape is fully consistent with the one derived from heliospheric imager observations of the June 2008 event. Conclusions. We have derived a mean shape of MC axis that only depends on one free parameter, the angular separation of the legs (as viewed from the Sun). This mean shape can be used in various contexts, such as studies of high-energy particles or space weather forecasts. © ESO, 2013.

Descripción: We discuss the global gravity wave (GW) activity expressed by the specific potential energy in the altitude range from 5 km below to 10 km above the tropopause, derived from GPS radio occultation data from CHAMP (2001-2008). The GW analysis is based on vertical detrending of the individual measured temperature profiles by applying a Gaussian filter in two different ways: (i) filtering of the complete temperature profiles and (ii) separate filtering of the profiles for the tropospheric and lower stratospheric parts. The separate filtering method significantly reduces the usually observed wave activity enhancement in the tropopause region which highly depends on the performance of the complete filtering method to reproduce the change in the temperature gradient at the tropopause. We only consider vertical wavelengths less than 10 km. The global mean potential energy in the tropopause region deduced with these different background temperatures will be analyzed, differences will be emphasized and possible error sources of the new method will be considered. Copyright 2008 by the American Geophysical Union.

Descripción: Localization of the epileptogenic zone is an important issue in epileptology, even though there is not a unique definition of the epileptic focus. The objective of the present study is to test ultrametric analysis to uncover cortical interactions in human epileptic data. Correlation analysis has been carried out over intraoperative Electro-Corticography (ECoG) data in 2 patients suffering from temporal lobe epilepsy (TLE). Recordings were obtained using a grid of 20 electrodes (5×4) covering the lateral temporal lobe and a strip of either 4 or 8 electrodes at the mesial temporal lobe. Ultrametric analysis was performed in the averaged final correlation matrices. By using the matrix of linear correlation coefficients and the appropriate metric distance between pairs of electrodes time series, we were able to construct Minimum Spanning Trees (MST). The topological connectivity displayed by these trees gives useful and valuable information regarding physiological and pathological information in the temporal lobe of epileptic patients. © 2007 American Institute of Physics.

Descripción: A suite of climate change indices derived from daily temperature and precipitation data, with a primary focus on extreme events, were computed and analyzed. By setting an exact formula for each index and using specially designed software, analyses done in different countries have been combined seamlessly. This has enabled the presentation of the most up-to-date and comprehensive global picture of trends in extreme temperature and precipitation indices using results from a number of workshops held in data-sparse regions and high-quality station data supplied by numerous scientists world wide. Seasonal and annual indices for the period 1951-2003 were gridded. Trends in the gridded fields were computed and tested for statistical significance. Results showed widespread significant changes in temperature extremes associated with warming, especially for those indices derived from daily minimum temperature. Over 70% of the global land area sampled showed a significant decrease in the annual occurrence of cold nights and a significant increase in the annual occurrence of warm nights. Some regions experienced a more than doubling of these indices. This implies a positive shift in the distribution of daily minimum temperature throughout the globe. Daily maximum temperature indices showed similar changes but with smaller magnitudes. Precipitation changes showed a widespread and significant increase, but the changes are much less spatially coherent compared with temperature change. Probability distributions of indices derived from approximately 200 temperature and 600 precipitation stations, with near-complete data for 1901-2003 and covering a very large region of the Northern Hemisphere midlatitudes (and parts of Australia for precipitation) were analyzed for the periods 1901-1950, 1951-1978 and 1979-2003. Results indicate a significant warming throughout the 20th century. Differences in temperature indices distributions are particularly pronounced between the most recent two periods and for those indices related to minimum temperature. An analysis of those indices for which seasonal time series are available shows that these changes occur for all seasons although they are generally least pronounced for September to November. Precipitation indices show a tendency toward wetter conditions throughout the 20th century.

Descripción: We study a piecewise linear version of a one-component, one-dimensional reaction-diffusion bistable model, with the aim of analyzing the effect of boundary conditions on the formation and stability of stationary patterns. The analysis proceeds through the study of the behavior of the Lyapunov functional in terms of a control parameter: the reflectivity at the boundary. We show that, in this example, this functional has a very simple and direct geometrical interpretation. © 1995 The American Physical Society.

Descripción: The recent solar minimum with very low activity provides us a unique opportunity for validating solar wind models. During CR2077 (2008 November 20 through December 17), the number of sunspots was near the absolute minimum of solar cycle 23. For this solar rotation, we perform a multi-spacecraft validation study for the recently developed three-dimensional, two-temperature, Alfvén-wave-driven global solar wind model (a component within the Space Weather Modeling Framework). By using in situ observations from the Solar Terrestrial Relations Observatory (STEREO) A and B, Advanced Composition Explorer (ACE), and Venus Express, we compare the observed proton state (density, temperature, and velocity) and magnetic field of the heliosphere with that predicted by the model. Near the Sun, we validate the numerical model with the electron density obtained from the solar rotational tomography of Solar and Heliospheric Observatory/Large Angle and Spectrometric Coronagraph C2 data in the range of 2.4 to 6 solar radii. Electron temperature and density are determined from differential emission measure tomography (DEMT) of STEREO A and B Extreme Ultraviolet Imager data in the range of 1.035 to 1.225 solar radii. The electron density and temperature derived from the Hinode/Extreme Ultraviolet Imaging Spectrometer data are also used to compare with the DEMT as well as the model output. Moreover, for the first time, we compare ionic charge states of carbon, oxygen, silicon, and iron observed in situ with the ACE/Solar Wind Ion Composition Spectrometer with those predicted by our model. The validation results suggest that most of the model outputs for CR2077 can fit the observations very well. Based on this encouraging result, we therefore expect great improvement for the future modeling of coronal mass ejections (CMEs) and CME-driven shocks. © 2012. The American Astronomical Society. All rights reserved.

Descripción: The present work was aimed at testing the hypothesis that mycorrhizal Prosopis alba, an economically important tree species worldwide, presents increased salt-tolerance compared with non-mycorrhizal ones and at gaining insight into the possible mechanisms underlying that improvement. For this purpose, a randomized complete block experiment with two factors: mycorrhizal treatments with or without the arbuscular fungus Glomus intraradices and two salinity levels, 0 and 200 mM NaCl was performed. Plant growth in P. alba plants colonized by G. intraradices was less affected by salinity than that in non-arbuscular mycorrhizal (AM) plants, indicating that mycorrhizal colonization turned P. alba more tolerant to salinity. Photosynthesis was reduced by salinity in non-AM plants but not in AM ones. Salinity caused a significant decrease in mean stomatal conductance and transpiration rate, in mycorrhizal plants, but not in uninoculated ones. In this work, we detected two main mechanisms intervening in the salt tolerance enhancement of P. alba by the inoculation with G. intraradices: a- maintaining the net photosynthesis level and b- control of the transpiration rate. Taken together, the results suggest that inoculation with G. intraradices improves P. alba survival rates during the implantation period and seems to be a promising strategy to improve P. alba cultivation in saline lands.

Descripción: The mammary epithelium undergoes cyclical periods of cellular proliferation, differentiation, and regression. During lactation, the signal transducer and activator of transcription factor (STAT)-5A and the glucocorticoid receptor (GR) synergize to induce milk protein expression and also act as survival factors. During involution, STAT3 activation mediates epithelial cell apoptosis and mammary gland remodeling. It has been shown that the administration of glucocorticoids at weaning prevents epithelial cell death, probably by extracellular matrix breakdown prevention. Our results show that the synthetic glucocorticoid dexamethasone (DEX) modulates STAT5A and STAT3 signaling and inhibits apoptosis induction in postlactating mouse mammary glands, only when administered within the first 48 h upon cessation of suckling. DEX administration right after weaning delayed STAT5A inactivation and degradation, preserving gene expression of target genes as β-casein (bcas) and prolactin induced protein (pip). Weaning-triggered GR down-regulation is also delayed by the hormone treatment. Moreover, DEX administration delayed STAT3 activation and translocation into epithelial cells nuclei. In particular, DEX treatment impaired the increment in gene expression of signal transducer subunit gp130, normally up-regulated from lactation to involution and responsible for STAT3 activation. Therefore, the data shown herein indicate that glucocorticoids are able to modulate early involution by controlling the strong cross talk that GR, STAT5, and STAT3 pathways maintains in the mammary epithelium. Copyright © 2010 by The Endocrine Society.

Descripción: The bcl-X gene plays a critical role in apoptosis. Six different isoforms generated by tissue-specific promoter usage and alternative splicing were described. Some of them exert opposite effects on cell death. In mammary epithelial cells glucocorticoids induce bcl-X expression and increase the ratio bcl-XL (antiapoptotic)/bcl-XS (apoptotic) by activating P4 promoter, which contains two hormone response elements. Here we show that, on mouse thymocytes and T lymphocyte derivative S49 cells, glucocorticoids inhibited transcription from P4 and decreased the ratio bcl-X L/bcl-XS favoring apoptosis. Upon hormonal treatment, glucocorticoid receptor (GR), steroid receptor coactivator-1, and RNA polymerase II were transiently recruited to P4 promoter, whereas STAT5B was also recruited but remained bound. Concomitant with the release of GR, silencing mediator for retinoic acid receptor and thyroid hormone receptor and histone deacetylase 3 were recruited, histone H3 was deacetylated, and RNA polymerase II left the promoter. Inhibition of STAT5 activity reverted glucocorticoid repression to activation of transcription and was accompanied by stable recruitment of GR and RNA polymerase II to P4. © 2006 by The American Society for Biochemistry and Molecular Biology, Inc.

Descripción: Specific receptors for the different gp130 cytokines, as well as the cytokines themselves, are expressed in anterior pituitary cells, providing the basis for the regulation of hormone secretion and cell growth (Figure 2). During an inflammatory response, both IL-6 and LIF increase (15, 17). LPS stimulates intrapituitary IL-6 production in FS cells via specific Toll receptors using the p38 MAPK-NF-κB pathway (20). Anti-IL-6 antibodies block the ACTH response of rat anterior pituitary cell cultures to LPS, showing the involvement of locally produced IL-6 (U. Renner et al., unpublished observations). Thus, during acute or chronic inflammation or infection, systemic, hypothalamic, or hypophyseal gp 130 cytokines may act on anterior pituitary cells, integrating the neuroendocrine response. The action of gp130 cytokines through the STAT3 transcription factor represents a powerful mechanism for regulation of pituitary corticotroph function. In response to different stressful stimuli, CRH stimulates the corticotrophs through cAMP/protein kinase A-mediated and calcium-mediated pathways and AP-1, CREB, and Nurr transcription factors. Cytokines may act on corticotrophs through different mechanisms; whereas IL-1 acts through Nur77, gp130 employs STAT3 for transcriptional activation. Cooperation between STAT3 and other transcription factors, such as NF-κB, AP-1, or the glucocorticoid receptor, has been described in other tissues (6), but it remains to be established whether this occurs in the pituitary. Future research clarifying the molecular mechanisms of gp130 action on pituitary cells will provide new clues regarding their involvement in neuro-endocrine responses to immune stimulation and will be of great importance for understanding pituitary pathophysiology.

Descripción: The Sierras Australes of Buenos Aires are located in the south-west corner Of the Province about 100 km west of Bahia Bianca. On the south-west flank of these hills, younger Palaeozoic sedimentary formations overlie poorly exposed granitic and volcanic basement rocks. Granitic Cerro Colorado outcrops, located 16 km strike to the south of the town of San Martin de Tours, and near Lago Los Chilenos, have been included in this broadly interpreted "basement" in many previous geological studies. This contribution is mainly based on detailed structural mapping of the cerro Colorado area, and systematic sampling of granitic and sedimentary rocks for petrographical, microtectonic and Rb/Sr isotopic age analysis. In contrast to previous studies, two Phanerozoic granitic units have been recognised and mapped in the cerro Colorado area of Sierras Australes. The older one, the Cerro Colorado Granite (CO, is composed of foliated and sheared anisotropic granitic rocks with a Rb/Sr isochron age of 381±9 Ma (ir= 0.7035 ). The younger one, Los Chilenos Granite (LCh), consists of isotropic granophiric microgranite with a Rb/Sr isochron age of 140 ±14 Ma (ir= 0.7126). This granite has intrusive contacts with both, the folded quartzite of the Mascota Formation and Cerro Colorado Granite (CC).The older tectomagmatic event (CO is correlated with the compressive Chanica Orogeny, which was associated in the Sierras Australes region, with the eruption of La Mascota - La Hermita rhyolites (360±21 Ma) and the unconformity between Lolén Formation (Middle Devonian) and Sauce Grande Formation (Carboniferous).The younger intrusive event of Los Chilenos Granite (LCh) is considered to be associated with an extensional tectonic regime during the Late Jurassic initial rifting of the Atlantic Ocean. O 1999 Asociación Gcológica.

Descripción: Los Chilenos granite: a new Jurassic granite unit in Cerro Colorado, Sierras Australes de Buenos Aires. Tectonic implication. The Sierras Australes of Buenos Aires are located in the south-west corner of the Province about 100 km west of Bahia Blanca. On the south-west flank of these hills, younger Palaeozoic sedimentary formations overlie poorly exposed granitic and volcanic basement rocks. Granitic Cerro Colorado outcrops, located 16 km strike to the south of the town of San Martin de Tours, and near Lago Los Chilenos, have been included in this broadly interpreted "basement" in many previous geological studies. This contribution is mainly based on detailed structural mapping of the cerro Colorado area, and systematic sampling of granitic and sedimentary rocks for petrographical, microtectonic and Rb/Sr isotopic age analysis. In contrast to previous studies, two Phanerozoic granitic units have been recognised and mapped in the cerro Colorado area of Sierras Australes. The older one, the Cerro Colorado Granite (CC), is composed of foliated and sheared anisotropic granitic rocks with a Rb/Sr isochron age of 381±9 Ma (ir= 0.7035). The younger one, Los Chilenos Granite (LCh), consists of isotropic granophiric microgranite with a Rb/Sr isochron age of 140 ± 14 Ma (ir= 0.7126). This granite has intrusive contacts with both, the folded quartzite of the Mascota Formation and Cerro Colorado Granite (CC).The older tectomagmatic event (CC) is correlated with the compressive Chañica Orogeny, which was associated in the Sierras Australes region, with the eruption of La Mascota - La Hermita rhyolites (360±21 Ma) and the unconformity between Lolén Formation (Middle Devonian) and Sauce Grande Formation (Carboniferous).The younger intrusive event of Los Chilenos Granite (LCh) is considered to be associated with an extensional tectonic regime during the Late Jurassic initial rifting of the Atlantic Ocean. © 1999 Asociación Geológica Argentina.

Descripción: 1. Mechanisms of grass- and forb-seed input and output in the central Monte desert of Argentina were studied in 1995 to test the hypothesis that seed consumption by autumn-winter granivores, especially birds, has qualitative as well as quantitative effects on soil-seed reserves. 2. The abundance of perennial grass seeds in late summer soils (≃ 2400 seeds m-2 or 0.36 g m-2) remained unchanged the following early spring (≃ 2700 seeds m-2 or 0.39 g m-2), despite the incorporation of about 3000 seeds m-2 or 0.71 g m-2 newly produced grass seeds during autumn-winter. Grass seeds appeared to be heavily consumed, especially the medium-sized ones. 3. The annual forb-seed bank was about the same size in late summer (≃ 5500 seeds m-2 or 1.34 g m-2) as in early spring (≃ 6500 seeds m-2 or 1.53 g m-2). Since forb-seed production had been relatively low (≃ 400 seeds m-2 or 0.12 g m-2), these seeds apparently suffered negligible postdispersal losses. 4. This pattern of grass- and forb-seed loss coincides with the pattern of seed consumption by granivorous birds - on average, 93% of seed mass in bird stomachs was from grass seeds, while only 7% was from forb seeds. 5, Further evidence of a major impact of bird foraging on seed reserves is that the mass of particular grass seeds that was lost from soils was positively correlated with the mass of such seeds in bird diets, and that the main target of bird consumption, i.e. medium-sized grass seeds, suffered the highest postdispersal loss. 6. It is concluded that autumn-winter granivores in the central Monte desert, particularly birds, mainly consume newly produced grass seeds and that they might have major qualitative as well as quantitative impacts on soil-seed reserves.

Descripción: In this work we study gravitational lensing of neutrinos by Schwarzschild black holes. In particular, we analyze the case of a neutrino transient source associated with a gamma-ray burst lensed by a supermassive black hole located at the center of an interposed galaxy. We show that the primary and secondary images have an angular separation beyond the resolution of forthcoming km-scale detectors, but the signals from each image have time delays between them that in most cases are longer than the typical duration of the intrinsic events. In this way, the signal from different images can be detected as separate events coming from the very same location in the sky. This would render an event that otherwise might have had a low signal-to-noise ratio a clear detection, since the probability of a repetition of a signal from the same direction is negligible. The relativistic images are so faint and proximate that are beyond the sensitivity and resolution of the next-generation instruments. © 2008 Elsevier B.V. All rights reserved.

Descripción: A significant wave activity in the upper troposphere and lower stratosphere at midlatitudes (30-40S) above the Andes Range was recently detected from Global Positioning System Radio Occultation (GPS RO) temperature profiles, retrieved from SAC-C (Satélite de Aplicaciones Cientficas-C and CHAMP (CHAllenging Minisatellite Payload) satellites. Previously, large amplitude, long vertical wavelength structures have been reported in this region, as detected from other limb-sounding devices and have been identified as mountain waves (MWs). The capability of GPS RO observations to detect typical MWs with horizontal wavelengths shorter than 150 km, as well as the proper association of the observed wave activity to mountain forcing is put in doubt. Other three possible sources are discussed. In particular, the generation of inertio-gravity waves by geostrophic adjustment near to a permanent jet situated above the mountains, may constitute another important mechanism in this region. These waves may possess longer horizontal and perhaps shorter vertical wavelengths than those typically expected in MWs and could be more easily detected from limb-sounding profiles. The "jet" mechanism will be discussed in a second paper. Copyright 2005 by the American Geophysical Union.

Descripción: A significant wave activity (WA) in the upper troposphere and lower stratosphere, mainly during winter, was detected at midlatitudes in the southern hemisphere (30-40S) above the Andes Range, from an analysis of Global Positioning System Radio Occultation (GPS RO) temperature profiles retrieved by CHAMP (CHAllenging Mini-satellite Payload) and SAC-C (Satélite de Aplicaciones Científicas-C) Low Earth Orbit (LEO) satellites, between May 2001 and February 2006. The possible main gravity wave sources in this region are: i) orographic forcing, ii) geostrophic adjustment and iii) deep convection. The available vertical resolution of GPS RO soundings does not rule out any of these alternatives. Based on satellite imaginary, the WA enhancements cannot be attributed to deep convection events. Inertia-gravity waves (IGWs) could be generated after a geostrophic adjustment process, following a perturbation of the zonal jet situated above the Andes Mountains by mountain waves (MWs). The monthly WA intensity follows the zonal wind velocity strength according to its seasonal variability at jet altitudes. As the GPS-LEO lines of sight are roughly meridionally aligned and the morphology of the Andes at middle latitudes is predominantly north-south, it was possible to detect MWs as well as IGWs from GPS RO temperature profiles. This characteristic does not apply for other mountain range alignments. From the analysis of a numerical simulation at the time and location of a single RO event with very strong WA, two main modes of oscillation with horizontal wavelength around 40 and 200 km were identified. The first one is attributed to a MW and the second one to an IGW. Copyright 2006 by the American Geophysical Union.

Descripción: We first study the seasonal and geographical behavior of gravity wave activity in the lower stratosphere over the southernmost Andes mountains and their prolongation in the Antarctic Peninsula by global positioning system (GPS) radio occultation (RO) temperature profiles, obtained between years 2002 and 2005 by the CHAllenging Minisatellite Payload (CHAMP) mission. The observed features complement observations in the same zone by other satellite passive remote sensing instruments, which are able to detect different height regions and other spectral intervals of the wave spectrum. Comparisons with previous GPS RO studies in smaller areas than the one covered in our analysis are also established. Significant seasonal variation of wave activity is observed in our work, in agreement with results from other instruments. The locations of significant cases indicate that topography is an important source. Some strong wave activity is also found over open ocean. Critical level filtering is shown to have an attenuation effect, implying that a large fraction of the observed activity can be considered to be an outcome of mountain waves. The studied region has a significant advantage as compared to other regions of our planet: it generates wavefronts nearly aligned with the North-South direction (almost parallel to the mountains), whereby this geometry favors the wave detection by the nearly meridional line of sight characterizing most of the GPS RO observations used. A distribution of the observed gravity waves in terms of amplitudes and wavelengths is also presented.

Descripción: We prove that Ext•A(k, k) is a Gerstenhaber algebra, where A is a Hopf algebra. In case A = D(H) is the Drinfeld double of a finite-dimensional Hopf algebra H, our results imply the existence of a Gerstenhaber bracket on H•GS (H, H). This fact was conjectured by R. Taillefer. The method consists of identifying H •GS (H, H) ≅ Ext•A (k, k) as a Gerstenhaber subalgebra of H• (A, A) (the Hochschild cohomology of A).

Descripción: The regulation of cell migration is a highly complex process that is often compromised when cancer cells become metastatic. The microtubule cytoskeleton is necessary for cell migration, but how microtubules and microtubule-associated proteins regulate multiple pathways promoting cell migration remains unclear. Microtubule plus-end binding proteins (+TIPs) are emerging as important players in many cellular functions, including cell migration. Here we identify a +TIP, GTSE1, that promotes cell migration. GTSE1 accumulates at growing microtubule plus ends through interaction with the EB1+TIP. The EB1-dependent +TIP activity of GTSE1 is required for cell migration, as well as for microtubule-dependent disassembly of focal adhesions. GTSE1 protein levels determine the migratory capacity of both nontransformed and breast cancer cell lines. In breast cancers, increased GTSE1 expression correlates with invasive potential, tumor stage, and time to distant metastasis, suggesting that misregulation of GTSE1 expression could be associated with increased invasive potential. © 2012 Scolz et al.

Descripción: We derive a posteriori error estimates for singularly perturbed reaction-diffusion problems which yield a guaranteed upper bound on the discretization error and are fully and easily computable. Moreover, they are also locally efficient and robust in the sense that they represent local lower bounds for the actual error, up to a generic constant independent in particular of the reaction coefficient. We present our results in the framework of the vertex-centered finite volume method but their nature is general for any conforming method, like the piecewise linear finite element one. Our estimates are based on a H(div)-conforming reconstruction of the diffusive flux in the lowest-order Raviart-Thomas-Nédélec space linked with mesh dual to the original simplicial one, previously introduced by the last author in the pure diffusion case. They also rely on elaborated Poincaré, Friedrichs, and trace inequalities-based auxiliary estimates designed to cope optimally with the reaction dominance. In order to bring down the ratio of the estimated and actual overall energy error as close as possible to the optimal value of one, independently of the size of the reaction coefficient, we finally develop the ideas of local minimizations of the estimators by local modifications of the reconstructed diffusive flux. The numerical experiments presented confirm the guaranteed upper bound, robustness, and excellent efficiency of the derived estimates. © 2009 EDP Sciences SMAI.

Descripción: MAP kinases have been linked to guard cell signalling. Arabidopsis thaliana MAP Kinase 3 (MPK3) is known to be activated by abscisic acid (ABA) and hydrogen peroxide (H2O2), which also control stomatal movements. We therefore studied the possible role of MPK3 in guard cell signalling through guard cell-specific antisense inhibition of MPK3 expression. Such transgenic plants contained reduced levels of MPK3 mRNA in the guard cells and displayed partial insensitivity to ABA in inhibition of stomatal opening, but responded normally to this hormone in stomatal closure. However, ABA-induced stomatal closure was reduced compared with controls when cytoplasmic alkalinization was prevented with sodium butyrate. MPK3 antisense plants were less sensitive to exogenous H2O2, both in inhibition of stomatal opening and in promotion of stomatal closure, thus MPK3 is required for the signalling of this compound. ABA-induced H2O2 synthesis was normal in these plants, indicating that MPK3 probably acts in signalling downstream of H2O2. These results provide clear evidence for the important role of MPK3 in the perception of ABA and H 2O2 in guard cells. © The Authors (2007).

Descripción: Guido bonarelli is an important figure in the field of geology in Argentina and he constituted one of the most relevant geologists in the oil exploration in our country. of Italian origin, he was born in Ancona on July 25, 1871 and he died in montereano, January 11, 1951. He excelled in stratigraphy, geological survey, historical geology and paleontology, becoming a specialist in the taxonomy of Jurassic ammonites and the stratigraphy of the Central Apennines. His professional work began in Italy and continued in southeast Asia, south America, bolivia, Chile, Argentina and uruguay. During 1911-1918, he worked in the Dirección General de minas, Geología e Hidrografía of Argentina. He defined the sub-Andean ranges as an orographic complex and he pointed out the locations of oil and natural gas reservoirs. He developed his researches in several Argentinean provinces and in the pacific Chilean coast. During his second period of research in Argentina (1923 -1927), Guido bonarelli organized the Geological Division of YpF, and he intensified the oil exploration in the northwestern of Argentina, as well as in the provinces of mendoza, neuquén and the Comodoro rivadavia region. He developed a professional and academic team that dealt with the geology and the hydrocarbon exploration in the country. bonarelli discovered in 1891 a sedimentary horizon that has great importance and it serves as a baseline to characterize the global anoxic event known to the Cenomanian-turonian transition. this world-famous skyline has been named Livello Bonarelli as a posthumous tribute to his discoverer.

Descripción: A combination of two methodologies is presented for detection and mapping of gypsum using ASTER L3A imagery. One of the methodologies uses the Quartz index defined for the ASTER TIR subsystem, which can be used for gypsum detection given its low response in Qi. The other consists in the combination of two band ratios of the ASTER SWIR subsystem, (4/5)/(7/5), which allows the identification of gypsum highlighting its high response in 4/5 and low response in 7/5. Two areas in the Cordillera Principal in the province of Mendoza were selected as case studies, and a field survey was conducted in order to evaluate the results. Both techniques are proved successful, yet classify erroneously some pixels as gypsum. Errors by excess are different for each method, which allows for these two techniques to be combined using a "decision tree" classifier to solve the misclassifications.

Descripción: Heme oxygenase-1 (HO-1), an inducible enzyme that metabolizes the heme group, is highly expressed in human Kaposi sarcoma lesions. Its expression is up-regulated by the G protein-coupled receptor from the Kaposi sarcoma-associated herpes virus (vGPCR). Although recent evidence shows that HO-1 contributes to vGPCR-induced tumorigenesis and vascular endothelial growth factor (VEGF) expression, the molecular steps that link vGPCR to HO-1 remain unknown. Here we show that vGPCR induces HO-1 expression and transformation through the Gα12/13 family of heterotrimeric G proteins and the small GTPase RhoA. Targeted small hairpin RNA knockdown expression of Gα12, Gα13, or RhoA and inhibition of RhoA activity impair vGPCR-induced transformation and ho-1 promoter activity. Knockdown expression of RhoA also reduces vGPCR-induced VEFG-A secretion and blocks tumor growth in a murine allograft tumor model. NIH-3T3 cells expressing constitutively activated Gα13 or RhoA implanted in nude mice develop tumors displaying spindle-shaped cells that express HO-1 and VEGF-A, similarly to vGPCR-derived tumors. RhoAQL-induced tumor growth is reduced 80% by small hairpin RNA-mediated knockdown expression of HO-1 in the implanted cells. Likewise, inhibition of HO-1 activity by chronic administration of the HO-1 inhibitor tin protoporphyrin IX to mice reduces RhoAQL-induced tumor growth by 70%. Our study shows that vGPCR induces HO-1 expression through the Gα12/13/RhoA axes and shows for the first time a potential role for HO-1 as a therapeutic target in tumors where RhoA has oncogenic activity.