Precipitation downscaling using random cascades: a case study in Italy

Abstract. We present a Stochastic Space Random Cascade (SSRC) approach to downscale precipitation from a Global Climate Model (hereon, GCMs) for an Italian Alpine watershed, the Oglio river (1440 km2). The SSRC model is locally tuned upon Oglio river for spatial downscaling (approx. 2 km) of daily precipitation from the NCAR Parallel Climate Model. We use a 10 years (1990–1999) series of observed daily precipitation data from 25 rain gages. Scale Recursive Estimation coupled with Expectation Maximization algorithm is used for model estimation. Seasonal parameters of the multiplicative cascade are accommodated by statistical distributions conditioned upon climatic forcing, based on regression analysis. The main advantage of the SSRC is to reproduce spatial clustering, intermittency, self-similarity of precipitation fields and their spatial correlation structure, with low computational burden.</p

Hybrid spreading mechanisms and T cell activation shape the dynamics of HIV-1 infection

HIV-1 can disseminate between susceptible cells by two mechanisms: cell-free infection following fluid-phase diffusion of virions and by highly-efficient direct cell-to-cell transmission at immune cell contacts. The contribution of this hybrid spreading mechanism, which is also a characteristic of some important computer worm outbreaks, to HIV-1 progression in vivo remains unknown. Here we present a new mathematical model that explicitly incorporates the ability of HIV-1 to use hybrid spreading mechanisms and evaluate the consequences for HIV-1 pathogenenesis. The model captures the major phases of the HIV-1 infection course of a cohort of treatment naive patients and also accurately predicts the results of the Short Pulse Anti-Retroviral Therapy at Seroconversion (SPARTAC) trial. Using this model we find that hybrid spreading is critical to seed and establish infection, and that cell-to-cell spread and increased CD4+ T cell activation are important for HIV-1 progression. Notably, the model predicts that cell-to-cell spread becomes increasingly effective as infection progresses and thus may present a considerable treatment barrier. Deriving predictions of various treatments' influence on HIV-1 progression highlights the importance of earlier intervention and suggests that treatments effectively targeting cell-to-cell HIV-1 spread can delay progression to AIDS. This study suggests that hybrid spreading is a fundamental feature of HIV infection, and provides the mathematical framework incorporating this feature with which to evaluate future therapeutic strategies

Revisión de las principales tecnologías de purificación de biogás

As it is necessary to propose a sustainable change in Argentinean energy matrix is important to study new sources of energy production to reduce dependency of hydrocarbons. Those compounds are not only in short supply but also its combustion produces greenhouse gases. Biogas is a valuable renewable fuel obtained from organic waste materials solving contamination problems and reducing greenhouse gases. Methane and carbon dioxide are its main components, but biogas also contains contaminants such as hydrogen sulphide and siloxanes. The presence of these compounds different than methane constitutes a problem because they are detrimental to any biogas processing equipment and they generate harmful emissions. Then, it is important to include biogas purification before its final use. This paper reviews the state of the art in biogas purification. A promising purification methods is absorption in aqueous solutions because it is economical and works for carbon dioxide and hydrogen sulphide removal. The paper presents an analysis of biogas purification processes showing its applicability.Fil: Morero, Betzabet del Valle. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Santa Fe. Instituto de Desarrollo Tecnológico Para la Industria Química (i); Argentina. Universidad Nacional del Litoral; ArgentinaFil: Groppelli, Eduardo. Universidad Nacional del Litoral. Facultad de Ingeniería Química; ArgentinaFil: Campanella, Enrique Angel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química (i); Argentina. Universidad Nacional del Litoral. Facultad de Ingeniería y Ciencias Hídricas; Argentin

Evaluation of future hydrological cycle under climate change scenarios in a mesoscale Alpine watershed of Italy

Abstract. We investigate future (2045–2054) hydrological cycle of the snow fed Oglio (≈1800 km2) Alpine watershed in Northern Italy. A Stochastic Space Random Cascade (SSRC) approach is used to downscale future precipitation from three general circulation models, GCMs (PCM, CCSM3, and HadCM3) available within the IPCC's data base and chosen for this purpose based upon previous studies. We then downscale temperature output from the GCMs to obtain temperature fields for the area. We also consider a projected scenario based upon trends locally observed in former studies, LOC scenario. Then, we feed the downscaled fields to a minimal hydrological model to build future hydrological scenarios. We provide projected flow duration curves and selected flow descriptors, giving indication of expected modified (against control run for 1990–1999) regime of low flows and droughts and flood hazard, and thus evaluate modified peak floods regime through indexed flood. We then assess the degree of uncertainty, or spread, of the projected water resources scenarios by feeding the hydrological model with ensembles projections consistent with our deterministic (GCMs + LOC) scenarios, and we evaluate the significance of the projected flow variables against those observed in the control run. The climate scenarios from the adopted GCMs differ greatly from one another with respect to projected precipitation amount and temperature regimes, and so do the projected hydrological scenarios. A relatively good agreement is found upon prospective shrinkage and shorter duration of the seasonal snow cover due to increased temperature patterns, and upon prospective increase of hydrological losses, i.e. evapotranspiration, for the same reason. However, precipitation patterns are less consistent, because HadCM3 and PCM models project noticeably increased precipitation for 2045–2054, whereas CCSM3 provides decreased precipitation patterns therein. The LOC scenario instead displays unchanged precipitation. The ensemble simulations indicate that several projected flow variables under the considered scenarios are significantly different from their control run counterparts, and also that snow cover seems to significantly decrease in duration and depth. The proposed hydrological scenarios eventually provide a what-if analysis, giving a broad view of the possible expected impacts of climate change within the Italian Alps, necessary to trigger the discussion about future adaptation strategies

Volcano monitoring from space using high-cadence planet CubeSat images applied to Fuego Volcano, Guatemala

Fuego volcano (Guatemala) is one of the most active and hazardous volcanoes in the world. Its persistent activity generates lava flows, pyroclastic density currents (PDCs), and lahars that threaten the surrounding areas and produce frequent morphological change. Fuego’s eruption deposits are often rapidly eroded or remobilized by heavy rains and its constant activity and inaccessible terrain makes ground-based assessment of recent eruptive deposits very challenging. Earth-orbiting satellites can provide unique observations of volcanoes during eruptive activity, when ground-based techniques may be too hazardous, and also during inter-eruptive phases, but have typically been hindered by relatively low spatial and temporal resolution. Here, we use a new source of Earth observation data for volcano monitoring: high resolution (~3 m pixel size) images acquired from a constellation of over 150 CubeSats (‘Doves’) operated by Planet Labs Inc. The Planet Labs constellation provides high spatial resolution at high cadence (\u3c1–72 h), permitting space-based tracking of volcanic activity with unprecedented detail. We show how PlanetScope images collected before, during, and after an eruption can be applied for mapping ash clouds, PDCs, lava flows, or the analysis of morphological change. We assess the utility of the PlanetScope data as a tool for volcano monitoring and rapid deposit mapping that could assist volcanic hazard mitigation efforts in Guatemala and other active volcanic regions

Quaternary sector collapses of Nevado de Toluca volcano (Mexico) governed by regional tectonics and volcanic evolution

Nevado de Toluca volcano is an andesiticdacitic composite volcano of Late Pliocene-Holocene age located in the central-eastern sector of the Trans-Mexican Volcanic Belt, an active continental arc. The latest stage of Nevado de Toluca evolution, in the past 50 k.y., has shown an interplay between volcanic activity and kinematics of the basement structures. Geological mapping, stratigraphic analysis, morphological and structural interpretation, and analogue modeling were used to investigate these complex volcano-tectonics relationships. In the past 50 k.y., Nevado de Toluca volcano underwent at least three sector collapses on the east, east-southeast, and west flanks because of faulting and destabilization of young dacitic domes at its summit. Field and remotely sensed data supported by analogue models of transtensive basement tectonics revealed that these catastrophic events were strongly correlated to the presence of the east-west-striking active Tenango fault system. The geometry, kinematics, and dynamics of the basement structure controlled the growth of a dome complex in the volcano summit and its destabilization. As a consequence of the active basement tectonics, the most probable sector collapse directions in the case of future gravitational failures of the volcano summit will be east-southeast, west-northwest, east, and west. Nevado de Toluca poses potential hazards to more than 25 million inhabitants; the analysis presented in this paper can improve hazard mitigation on the basis of better knowledge of growth and collapse mechanism of the volcano. The numerous examples of composite volcanoes in continental and island volcanic arcs with similar structural-volcanological characteristics of Nevado de Toluca volcano imply that the model results can also act as a guide to study the growth and collapse of other composite volcanoes affected by basement structures. © 2007 Geological Society of America

Immunohistochemical analysis of adhesive papillae of Clavelina lepadiformis (Müller, 1776) and Clavelina phlegraea (Salfi, 1929) (Tunicata, Ascidiacea)

Almost all ascidian larvae bear three mucus secreting and sensory organs, the adhesive papillae, at the anterior end of the trunk, which play an important role during the settlement phase. The morphology and the cellular composition of these organs varies greatly in the different species. The larvae of the Clavelina genus bear simple bulbous papillae, which are considered to have only a secretory function. We analysed the adhesive papillae of two species belonging to this genus, C. lepadiformis and C. phlegraea, by histological sections and by immunolocalisation of β-tubulin and serotonin, in order to better clarify the cellular composition of these organs. We demonstrated that they contain at least two types of neurons: central neurons, bearing microvilli, and peripheral ciliated neurons. Peripheral neurons of C. lepadiformis contain serotonin. We suggest that these two neurons play different roles during settlement: the central ones may be chemo- or mechanoreceptors that sense the substratum, and the peripheral ones may be involved in the mechanism that triggers metamorphosis

Comparación de diferentes soluciones de aminas para la purificación de biogás

El biogás es un valioso combustible renovable producido por la digestión anaeróbica de materia orgánica desechable. Sus principales componentes son metano (CH4), dióxido de carbono (CO2), agua (H2O) y ácido sulfhídrico (H2S). La presencia de anhídrido carbónico y ácido sulfhídrico constituye un problema ya que son perjudiciales para cualquier equipo de procesamiento de biogás y producen emisiones contaminantes. Entre las diversas tecnologías disponibles actualmente para purificar biogás, la absorción con aminas es una tecnología muy conveniente por su alta selectividad hacia el CO2 y el H2S. El presente trabajo compara la concentración de metano, anhídrido carbónico y ácido sulfhídrico en el gas endulzado y el consumo de energía en un proceso convencional de absorción-desorción para seis tipos de soluciones de aminas o mezclas de ellas.Fil: Morero, Betzabet del Valle. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; ArgentinaFil: Croquer Martinis, Carolina. Bryan Research & Engineering; Estados UnidosFil: Groppelli, Eduardo Santiago. Universidad Nacional del Litoral; ArgentinaFil: Campanella, Enrique Angel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; Argentin

Contact-induced mitochondria polarization supports HIV-1 virological synapse formation

Rapid HIV-1 spread between CD4 T lymphocytes occurs at retrovirus-induced immune cell contacts called virological synapses (VS). VS are associated with striking T cell polarization and localized virus budding at the site of contact that facilitates cell-cell spread. In addition to this, spatial clustering of organelles including mitochondria to the contact zone has been previously shown. However, whether cell-cell contact specifically induces dynamic T cell remodeling during VS formation and what regulates this process remains unclear. Here we report that contact between an HIV-1 infected T cell and an uninfected target T cell specifically triggers polarization of mitochondria concomitant with recruitment of the major HIV-1 structural protein Gag to the site of cell-cell contact. Using fixed and live cell imaging we show that mitochondria and Gag polarization in HIV-1 infected T cells occurs within minutes of contact with target T cells, requires the formation of stable cell-cell contacts and is an active, calcium-dependent process. We also find that perturbation of mitochondria polarization impairs cell-cell spread of HIV-1 at the VS. Taken together these data suggest that HIV-1 infected T cells are able to sense and respond to contact with susceptible target cells and undergo dynamic cytoplasmic remodeling to create a synaptic environment that supports efficient HIV-1 VS formation between CD4 T lymphocytes