Características de las parasitosis digestivas en bovinos de la provincia de Mendoza

Los bovinos son afectados por numerosas parasitosis, entre las cuales, las digestivas ocupan un rol central. Estas afectan la salud, el bienestar y provocan cuantiosas pérdidas económicas, llegando incluso a ser un factor limitante en la producción. En la Argentina han sido profusamente descritas y analizadas en la pampa húmeda, litoral, zona central, sin embargo, los estudios para el semiárido son escasos. El objetivo del presente trabajo es describir las parasitosis digestivas en bovinos de la provincia de Mendoza. Se procesaron 554 muestras de materia fecal de bovino discriminadas según procedencia de zona, 291 de zona de Monte (ZM) y 263 de zona de valle Andino (ZVA) según caracterización climática y agroecológica. Se realizaron las siguientes técnicas: sedimentación-flotación, Lumbreras y Wisconsin. Se hallaron 280 (50,54%) positivas a alguna parasitosis: trichostrongílidos 37%; Fasciola hepatica 13,5%; Eimeria spp. 11%; Trichuris spp. 0,36 %; Toxocara vitulorum, 1,99%; Moniezia spp. 0,18%; Nematodirus spp. 0,18%. Comparando las ZVA y ZM, se hallaron diferencias estadísticamente significativas referido a la prevalencia de F. hepatica, 27% y 1,37% respectivamente. Referido a la carga de tricostrongilidos, la mayoría, (73,6%) presentaron una carga de huevos por gramo (HPG) <10, y solo de muestras (0,98%) con cargas entre 200-500 HPG. Estas cargas permiten inferir, que, totalmente distinto a lo que ocurre en otras zonas productivas del país, en la provincia de Mendoza esta parasitosis no incide en la sanidad y producción bovina, probablemente debido a que la densidad del pastizal, temperatura y falta de precipitaciones y condiciones de manejo no la favorecen. La prevalencia de F. hepatica en ZVA indica que esta puede estar afectando seriamente la producción, además de ser una importante zoonosis. Estos resultados exponen la necesidad de realizar estudios parasitológicos en cada región para poder implementar las medidas de manejo adecuadas a cada situación

The MACHO project: Microlensing Optical Depth towards the Galactic Bulge from Difference Image Analysis

We present the microlensing optical depth towards the Galactic bulge based on the detection of 99 events found in our Difference Image Analysis (DIA) survey. This analysis encompasses three years of data, covering ~ 17 million stars in ~ 4 deg^2, to a source star baseline magnitude limit of V = 23. The DIA technique improves the quality of photometry in crowded fields, and allows us to detect more microlensing events with faint source stars. We find this method increases the number of detection events by 85% compared with the standard analysis technique. DIA light curves of the events are presented and the microlensing fit parameters are given. The total microlensing optical depth is estimated to be tau_(total)= 2.43^(+0.39/-0.38) x 10^(-6) averaged over 8 fields centered at l=2.68 and b=-3.35. For the bulge component we find tau_(bulge)=3.23^(+0.52/-0.50) x 10^(-6) assuming a 25% stellar contribution from disk sources. These optical depths are in good agreement with the past determinations of the MACHO Alcock et al. (1997) and OGLE Udalski et al. (1994) groups, and are higher than predicted by contemporary Galactic models. We show that our observed event timescale distribution is consistent with the distribution expected from normal mass stars, if we adopt the stellar mass function of Scalo (1986) as our lens mass function. However, we note that as there is still disagreement about the exact form of the stellar mass function, there is uncertainty in this conclusion. Based on our event timescale distribution we find no evidence for the existence of a large population of brown dwarfs in the direction of the Galactic bulge.Comment: Updated references and corrected optical depth values. tau_tot= [2.91(+0.47/-0.45) -> 2.43^(+0.39/-0.38)] x 10^(-6) tau_bul = [3.88(+0.63/-0.60) -> 3.23^(+0.52/-0.50)] x 10^(-6

Mutual information rate and bounds for it

The amount of information exchanged per unit of time between two nodes in a dynamical network or between two data sets is a powerful concept for analysing complex systems. This quantity, known as the mutual information rate (MIR), is calculated from the mutual information, which is rigorously defined only for random systems. Moreover, the definition of mutual information is based on probabilities of significant events. This work offers a simple alternative way to calculate the MIR in dynamical (deterministic) networks or between two data sets (not fully deterministic), and to calculate its upper and lower bounds without having to calculate probabilities, but rather in terms of well known and well defined quantities in dynamical systems. As possible applications of our bounds, we study the relationship between synchronisation and the exchange of information in a system of two coupled maps and in experimental networks of coupled oscillators

Microlensing optical depth towards the Galactic bulge from MOA observations during 2000 with Difference Image Analysis

We analyze the data of the gravitational microlensing survey carried out by by the MOA group during 2000 towards the Galactic Bulge (GB). Our observations are designed to detect efficiently high magnification events with faint source stars and short timescale events, by increasing the the sampling rate up to 6 times per night and using Difference Image Analysis (DIA). We detect 28 microlensing candidates in 12 GB fields corresponding to 16 deg^2. We use Monte Carlo simulations to estimate our microlensing event detection efficiency, where we construct the I-band extinction map of our GB fields in order to find dereddened magnitudes. We find a systematic bias and large uncertainty in the measured value of the timescale $t_{\rm Eout}$ in our simulations. They are associated with blending and unresolved sources, and are allowed for in our measurements. We compute an optical depth tau = 2.59_{-0.64}^{+0.84} \times 10^{-6} towards the GB for events with timescales 0.3<t_E<200 days. We consider disk-disk lensing, and obtain an optical depth tau_{bulge} = 3.36_{-0.81}^{+1.11} \times 10^{-6}[0.77/(1-f_{disk})] for the bulge component assuming a 23% stellar contribution from disk stars. These observed optical depths are consistent with previous measurements by the MACHO and OGLE groups, and still higher than those predicted by existing Galactic models. We present the timescale distribution of the observed events, and find there are no significant short events of a few days, in spite of our high detection efficiency for short timescale events down to t_E = 0.3 days. We find that half of all our detected events have high magnification (>10). These events are useful for studies of extra-solar planets.Comment: 65 pages and 30 figures, accepted for publication in ApJ. A systematic bias and uncertainty in the optical depth measurement has been quantified by simulation

Interregionalism's impact on regional integration in developing countries: the case of Mercosur

This article examines the impact of interregionalism on deepening regional integration processes in non-European Union (EU) regions, specifically the Southern Common Market (Mercosur). It considers whether ‘capacity-building’ functions of interregionalism are present in EU–Mercosur relations. It argues that although negotiations for an association agreement might have helped Mercosur survive periods of severe crisis in the past, the terms of the agreement under negotiation were not sufficiently attractive to encourage deeper integration in Mercosur. Moreover, interregionalism cannot be expected to compensate for low institutionalization, nor substitute for weak political willingness to deepen integration. Ultimately, Mercosur alone can decide how far it wants to take its regional integration

Contamination level and spatial distribution of heavy metals in water and sediments of El Guájaro Reservoir, Colombia

Heavy metals have become a subject of special concern worldwide, mainly due to high persistence in the environment, toxicity, biogeochemical recycling and ecological risk. Therefore, the objective of this investigation was to analyze the spatial–temporal distribution of heavy metals in water and sediments to determine the environmental status of El Guájaro Reservoir, where such studies have not been developed. Two measurement campaigns (dry and wet period) were carried out and eight sampling stations were selected. A comparison of water and sediment quality parameters with existing national and international regulations was done. Also, heavy metal distribution maps were generated, and the geoaccumulation index was calculated to identify sources and sediments contamination level. Based on the obtained results, agriculture and mining activities are the main causes of the reservoir contamination. This metals levels could be a potential risk for the aquatic life and the populations that are supplied from this water body

Tick and host derived compounds detected in the cement complex substance

Ticks are obligate hematophagous arthropods and vectors of pathogens affecting human and animal health worldwide. Cement is a complex protein polymerization substance secreted by ticks with antimicrobial properties and a possible role in host attachment, sealing the feeding lesion, facilitating feeding and pathogen transmission, and protection from host immune and inflammatory responses. The biochemical properties of tick cement during feeding have not been fully characterized. In this study, we characterized the proteome of Rhipicephalus microplus salivary glands (sialome) and cement (cementome) together with their physicochemical properties at different adult female parasitic stages. The results showed the combination of tick and host derived proteins and other biomolecules such as a-Gal in cement composition, which varied during the feeding process. We propose that these compounds may synergize in cement formation, solidification and maintenance to facilitate attachment, feeding, interference with host immune response and detachment. These results advanced our knowledge of the complex tick cement composition and suggested that tick and host derived compounds modulate cement properties throughout tick feeding

The evolution of the Galactic metallicity gradient from high-resolution spectroscopy of open clusters

Open clusters offer a unique possibility to study the time evolution of the radial metallicity gradients of several elements in our Galaxy, because they span large intervals in age and Galactocentric distance, and both quantities can be more accurately derived than for field stars. We re-address the issue of the Galactic metallicity gradient and its time evolution by comparing the empirical gradients traced by a sample of 45 open clusters with a chemical evolution model of the Galaxy. At variance with previous similar studies, we have collected from the literature only abundances derived from high--resolution spectra. The clusters have distances $7 < RGC<22$ kpc and ages from $\sim 30$ Myr to 11 Gyr. We also consider the $\alpha$-elements Si, Ca, Ti, and the iron-peak elements Cr and Ni. The data for iron-peak and $\alpha$-elements indicate a steep metallicity gradient for R_GC<12$kpc and a plateau at larger radii. The time evolution of the metallicity distribution is characterized by a uniform increase of the metallicity at all radii, preserving the shape of the gradient, with marginal evidence for a flattening of the gradient with time in the radial range 7-12 kpc. Our model is able to reproduce the main features of the metallicity gradient and its evolution with an infall law exponentially decreasing with radius and with a collapse time scale of the order of 8 Gyr at the solar radius. This results in a rapid collapse in the inner regions, i.e.$R_{\rm GC}\lesssim 12$ kpc (that we associate with an early phase of disk formation from the collapse of the halo) and in a slow inflow of material per unit area in the outer regions at a constant rate with time.Comment: 16 pages, 18 figures, A&A accepte

“Capacidad de transmisión de fasciola hepatica de lymnaeidos de la Provincia de Mendoza”

La fascioliasis es una enfermedad producida por trematodos hepáticos del género Fasciola (Trematoda: Fasciolidae), los cuales, para completar su ciclo, necesitan caracoles acuáticos de la familia Lymnaeidae. Esta enfermedad, no solo produce cuantiosas pérdidas a la ganadería, sino que también es una importante zoonosis que afecta a millones de personas en América, Europa, África, Asia y Oceanía

The Pressure of an Equilibrium Interstellar Medium in Galactic Disks

Based on an axisymmetric galactic disk model, we estimate the equilibrium gas pressure P/k in the disk plane as a function of the galactocentric distance R for several galaxies (MW, M33, M51, M81, M100, M101, M106, and the SMC). For this purpose, we solve a self-consistent system of equations by taking into account the gas self-gravity and the presence of a dark pseudo-isothermal halo. We assume that the turbulent velocity dispersions of the atomic and molecular gases are fixed and that the velocity dispersion of the old stellar disk corresponds to its marginal stability (except for the Galaxy and the SMC). We also consider a model with a constant disk thickness. Of the listed galaxies, the SMC and M51 have the highest pressure at a given relative radius R/R_25, while M81 has the lowest pressure. The pressure dependence of the relative molecular gas fraction confirms the existence of a positive correlation between these quantities, but it is not so distinct as that obtained previously when the pressure was estimated very roughly. This dependence breaks down for the inner regions of M81 and M106, probably because the gas pressure has been underestimated in the bulge region. We discuss the possible effects of factors other than the pressure affecting the relative content of molecular gas in the galaxies under consideration.Comment: 10 pages, 5 figure