Cambios en la física del suelo e incrementos de la escorrentía y la erosión tras un incendio forestal

[Resumen] Los cambios en las propiedades físicas del suelo después de un incendio forestal, determinan una menor capacidad de infiltración y son responsables del incremento de escorrentía y erosión. El siguiente artículo analiza la textura, la porosidad y la estabilidad estructural del suelo de un bosque quemado en 1993. Se analizan también las diferencias que las intensidades del fuego pudieron tener en estas propiedades. Estos aspectos son comparados entre una parcela control de bosque y tres áreas afectadas por diferentes intensidades del incendio. Se han obtenido tasas de escorrentía hasta 8 veces superiores en la zona de intensidad alta, y tasas de erosión 30 veces superiores en episodios concretos de precipitación. La suma de los efectos producidos en la física del suelo, así como la desprotección del mismo por parte de la vegetación explicarían el aumento de la escorrentía y la erosión.[Abstract] Runoff and erosion increment after forest fires are, in part, a consequence of changes in the physical properties of the soil. This paper analizes the texture, porosity and aggregate stability of the soil of a forest burnt in 1993. The differences of these properties as a consequence of different fire intensities are also analized. As a consequence of these changes the soil has less infiltration capacity, and there is an increment of runoff and erosiono These two aspects are compared between a control plot in the forest, and in three areas afected with different fire intensity. Runoff increases 8 times and erosion 30 times in the high fire intensity area during concret rainfal1 events. The effects of fire in the physical properties plus the burnt of vegetation explain the increases of runoff and erosion

Water diffusion modulates the cest effect on Tb(III)-mesoporous silica probes

The anchoring of lanthanide(III) chelates on the surface of mesoporous silica nanoparticles (MSNs) allowed their investigation as magnetic resonance imaging (MRI) and chemical exchange saturation transfer (CEST) contrast agents. Since their efficiency is strongly related to the interaction occurring between Ln-chelates and \u201cbulk\u201d water, an estimation of the water diffusion inside MSNs channels is very relevant. Herein, a method based on the exploitation of the CEST properties of TbDO3A-MSNs was applied to evaluate the effect of water diffusion inside MSN channels. Two MSNs, namely MCM-41 and SBA-15, with different pores size distributions were functionalized with TbDO3A-like chelates and polyethylene glycol (PEG) molecules and characterized by HR-TEM microscopy, IR spectroscopy, N2 physisorption, and thermogravimetric analysis (TGA). The different distribution of Tb-complexes in the two systems, mainly on the external surface in case of MCM-41 or inside the internal pores for SBA-15, resulted in variable CEST efficiency. Since water molecules diffuse slowly inside silica channels, the CEST effect of the LnDO3A-SBA-15 system was found to be one order of magnitude lower than in the case of TbDO3A-MCM-41. The latter system reaches an excellent sensitivity of ca. 55 \ub1 5 \ub5M, which is useful for future theranostic or imaging applications

Phage inducible islands in the gram-positive cocci

The SaPIs are a cohesive subfamily of extremely common phage-inducible chromosomal islands (PICIs) that reside quiescently at specific att sites in the staphylococcal chromosome and are induced by helper phages to excise and replicate. They are usually packaged in small capsids composed of phage virion proteins, giving rise to very high transfer frequencies, which they enhance by interfering with helper phage reproduction. As the SaPIs represent a highly successful biological strategy, with many natural Staphylococcus aureus strains containing two or more, we assumed that similar elements would be widespread in the Gram-positive cocci. On the basis of resemblance to the paradigmatic SaPI genome, we have readily identified large cohesive families of similar elements in the lactococci and pneumococci/streptococci plus a few such elements in Enterococcus faecalis. Based on extensive ortholog analyses, we found that the PICI elements in the four different genera all represent distinct but parallel lineages, suggesting that they represent convergent evolution towards a highly successful lifestyle. We have characterized in depth the enterococcal element, EfCIV583, and have shown that it very closely resembles the SaPIs in functionality as well as in genome organization, setting the stage for expansion of the study of elements of this type. In summary, our findings greatly broaden the PICI family to include elements from at least three genera of cocci

Delivery actuator for a transcervical sterilization device

The use of delivery systems in the human body for positioning and deploying implants, such as closure devices, dilation balloons, stents, coils and sterilization devices, are gaining more importance to preclude surgical incisions and general anesthesia. The majorities of the non-surgical medical devices are delivered in a low profile into human body form and subsequently require specialized operations for their deployment and release. An analogous procedure for permanent female sterilization is the transcervical approach that does not require either general anesthesia or surgical incision and uses a normal body passage. The objective of this paper is to detail the design, development and verification of an ergonomic actuator for a medical application. In particular, this actuator is designed for the deployment and release of an implant to achieve instant permanent female sterilization via the transcervical approach. This implant is deployed under hysteroscopic visualization and requires a sequence of rotary and linear operations for its deployment and release. More specifically, this manually operated actuator is a hand held device designed to transmit the required forces in a particular sequence to effect both implant deployment and release at a target location. In order to design the actuator and to investigate its mechanical behavior, a three-dimensional (3D) Computer Aided Design (CAD) model was developed and Finite Element Method (FEM) was used for simulations and optimization. Actuator validation was performed following a number of successful bench-top in-air deployments and in-vitro deployments in animal tissue and explanted human uteri. During these deployments it was observed that the actuator applied the required forces to the implant resulting in successful deployment. Initial results suggest that this actuator can be used single handedly during the deployment phase. The ongoing enhancement of this actuator is moving towards “first-in- man” clinical trials

Validation of ERA5-Land temperature and relative humidity on four Peruvian glaciers using on-glacier observations

Weather and climate conditions drive the evolution of tropical glaciers which play an important role as water reservoirs for Peruvian inhabitants in the arid coast and semi-arid Andean region. The scarcity of long-term high-quality observations over Peruvian glaciers has motivated the extensive use of reanalysis data to describe the climatic evolution of these glaciers. However, the representativeness and uncertainties of these reanalysis products over these glaciers are still poorly constrained. This study evaluates the ability of the ERA5-Land reanalysis (ERA5L) to reproduce hourly and monthly 2 m air temperature and relative humidity (T2m and Rh2m, respectively) over several Peruvian glaciers. We compared the ERA5L with data from four on-glacier automatic weather stations (AWS), whose hourly time series were completed with nearby stations, for the period January 2017 to December 2019. Results indicates a better performance of the reanalysis for T2m (r >0.80) than for Rh2m (similar to 0.4<

Estimación de la fitomasa aérea mediante el uso del disco en una asociación de alfalfa y pasto ovillo

El objetivo del presente trabajo fue el de calibrar un disco para relacionar altura con rendimiento de forraje. Se utilizaron dos pasturas asociadas de alfalfa (Medicago saliva L.) y pasto ovillo (Dactylis glomerata). Es importante destacar que ambas pasturas eran alfalfas dominantes (alfalfa 78% y pasto ovillo 22%). Este método se evaluó para ser utilizado como un método práctico y rápido que permita estimar el rendimiento forrajero (kg MS/ha). La calibración se realizó en el establecimiento agropecuario "La María Pilar", ubicado en el departamento Catriló, durante otoño, primavera y verano de 1995 y verano de 1996. Los muestreos se realizaron al iniciar el pastoreo. La frecuencia de corte fue de. 23 días y se efectuaron 10 estimaciones en cada pastura. En cada fecha de corte se tomaron 30 muestras circulares de 0,166 m2 de superficie, se cortaron y secaron en estufa. La fitomasa se relacionó con la altura medida con el disco. Dicha relación fue lineal (p<0,05). No se encontraron diferencias (p<0,05) entre pasturas y fechas de muestreo. Se obtuvo una ecuación general Y = 134,7 x H donde Y = fitomasa aérea (kg/ha) y H = altura medida con el disco (cm). Esta no permitió lograr estimaciones confiables de la fitomasa aérea. Sin embargo, el método podría ser utilizado en un procedimiento de doble muestreo que consistida en realizar un número importante de estimaciones con el disco y relacionarlo con un pequeño número de cortes. Este método, si bien puede no tener aplicaciones en los casos en que se desee lograr gran precisión en la estimación de rendimientos, tienen la gran ventaja de su facilidad de uso y rapidez y podría ser usado a nivel productor, previa calibración por un técnico.Director: lng. Agr. Oscar Hernández y Codirector: lng. Agr. Carlos María Ferri, Cátedra de Forrajicultura y manejo de pasturas

The M4 Core Project with HST --- I. Overview and First-Epoch

We present an overview of the ongoing Hubble Space Telescope large program GO-12911. The program is focused on the core of M4, the nearest Galactic globular cluster, and the observations are designed to constrain the number of binaries with massive companions (black holes, neutron stars, or white dwarfs) by measuring the ``wobble'' of the luminous (main-sequence) companion around the center of mass of the pair, with an astrometric precision of ~50 micro-arcseconds. The high spatial resolution and stable medium-band PSFs of WFC3/UVIS will make these measurements possible. In this work we describe: (i) the motivation behind this study, (ii) our observing strategy, (iii) the many other investigations enabled by this unique data set, and which of those our team is conducting, and (iv) a preliminary reduction of the first-epoch data-set collected on October 10, 2012.Comment: 25 pages, 14 figures (9 at low resolution), 3 tables. Published in: Astronomische Nachrichten, Volume 334, Issue 10, pages 1062-1085, December 2013. http://onlinelibrary.wiley.com/doi/10.1002/asna.201311911/abstrac

Influence of Maturity and Vineyard Location on Free and Bound Aroma Compounds of Grapes from the País Cultivar

Some of the volatile compounds present in grapes give wine is its unique and genuine characteristics.  “Terroir” and berry maturity are considered to be the main influences on the expression of these characteristics. This work was undertaken to establish the specific characteristics that define Vitis vinifera cv. País, based on its aromatic profile and free and bound compounds (glycosides), and to assess the effects of location and maturity. Free and bound volatile compounds presented significant differences in the three locations studied. The total amount of free alcohols, acids and ketones depended on the location. During ripening, the amount of aroma precursors increased in all chemical groups in every location studied, and they were found mainly in the skins. With reference to free volatile compounds, it was found that cis-2-hexenol could be a good candidate to assess maturity, and that terpene content seemed to be strongly related to the vineyard location and cultivar conditions. Also, data analysis showed that the free aroma profile seemed to be influenced more by the maturity of the grapes and the bound aroma fraction more by the location

M4 Core Project with HST - III. Search for variable stars in the primary field

We present the results of a photometric search for variable stars in the core of the Galactic globular cluster M4. The input data are a large and unprecedented set of deep Hubble Space Telescope WFC3 images (large program GO-12911; 120 orbits allocated), primarily aimed at probing binaries with massive companions by detecting their astrometric wobbles. Though these data were not optimised to carry out a time-resolved photometric survey, their exquisite precision, spatial resolution and dynamic range enabled us to firmly detect 38 variable stars, of which 20 were previously unpublished. They include 19 cluster-member eclipsing binaries (confirming the large binary fraction of M4), RR Lyrae, and objects with known X-ray counterparts. We improved and revised the parameters of some among published variables.Comment: 11 pages, 5 figures, 2 tables. Accepted for publication in MNRA