Management discriminant properties in semiarid soils

The physical properties of coarse - textured soils in semiarid regions often deteriorate with use. We hypostatized that the changes in the physical properties of the soil were related to the cropping sistem employed. 5urface sampled of 52 Entic Haplustolls under three diferents uses (24 under continuous cultivation), 18 under rotation wuth grass Ieys (R), and 10 virgin soils M were analyzed for c1ay, silt, organic malter anrd water content, bulk density, compaction and aggregate stability. Data were analyzed statistically using principal components, canonical variables, and discriminant functions. A satisfactory segregation of the soils according to discriminant properties (coarse organic matter, aggregate stability, and suceptibility lo compaction) was obtained. The model developed satisfactory classified the soils under different uses (100% R, 83% e, and 88% V). Principal component analysis also showed that bulck density, compaction, and wet aggregate salability are related lo organic matter content. We conclude that, in the studied region, the lower the ratio of organic matter lo clay + soil content, the more severe the physical deterioration of the soils.Resúmenes de Trabajos presentados en otras publicaciones (por docentes de la UNLPam.)Publicado en Soil Science, Vol 163 N°7

Vanishing Cosmological Constant in Modified Gauss-Bonnet Gravity with Conformal Anomaly

We consider dark energy cosmology in a de Sitter universe filled with quantum conformal matter. Our model represents a Gauss-Bonnet model of gravity with contributions from quantum effects. To the General Relativity action an arbitrary function of the GB invariant, f(G), is added, and taking into account quantum effects from matter the cosmological constant is studied. For the considered model the conditions for a vanishing cosmological constant are considered. Creation of a de Sitter universe by quantum effects in a GB modified gravity is discussed.Comment: 8 pages latex, 1 figure. To appear in Int. J. Mod. Phys.

Estructura de tallas y composición sexual de Eurypodius Latreillii Guérin, 1828 (Brachyura) y Pagurus Comptus White, 1847 (Anomura) en el extremo sur de Chile

The decapod crustaceans Eurypodius latreillii (Brachyura) and Pagurus comptus (Paguridae) were the most frequently occurring species in Agassiz trawl (AGT) samples obtained during the Chilean - German - Italian Victor Hensen Expedition in the Straits of Magellan and south of the Beagle Channel. Sex composition and length structure aspects were studied using the material from 15 stations in the two areas, which comprised 773 specimens of E. latreillii and 647 P. comptus. The size frequency of both species was characterized by the presence of small individuals in shallow waters. The sex composition varied with depth, indicating a dominance of E. latreillii females in deep waters, whereas no such pattern was observed in P. comptus. These differences may be caused by epizoites of E. latreillii and the availability of vacant gastropod shells for P. comptus, in addition to geographical aspects and life-cycle patterns of these speciesLos crustáceos decápodos Eurypodius latreillii (Brachyura) y Pagurus comptus (Anomura), fueron las especies encontradas con mayor frecuencia en las muestras obtenidas durante la Expedición Chilena - Alemana - Italiana “Victor Hensen” (Octubre/Noviembre de 1994) en el Estrecho de Magallanes y al sur del Canal del Beagle, en el extremo sur de Chile. En estas localidades se obtuvieron las muestras mediante una red de tipo Agassiz. Los ejemplares fueron medidos, pesados y sexados, posteriormente se analizó la composición sexual y la estructura de tallas de estas especies. Se recolectaron un total de 773 individuos de E. latreillii y 647 individuos de P. comptus. Este material corresponde a los especímenes capturados en 15 estaciones. La estructura de tallas para ambas especies se caracterizó por la presencia de ejemplares de menor tamaño hacia zonas someras. La composición sexual presentó variaciones respecto de la profundidad, indicando una dominancia de hembras en aguas profundas para E. latreillii, pero este patrón no se observó en P. comptus. Los patrones observados dependerían de la presencia de epibiontes sobre el caparazón de E. latreillii y la disponibilidad de conchas vacías de gastrópodos para P. comptus, además de aspectos geográficos y de los ciclos de vida que presentarían ambas especies en la región

Producción de huevos en Eurypodius latreillii Guérin, 1828 (Decapoda: Majidae) en el Estrecho de Magallanes, sur de Chile

Egg production and reproductive investment were studied in the spider crab Eurypodius latreillii from the Straits of Magellan, southern Chile. A total of 66 ovigerous females were analyzed, ranging in size from 29.0 to 62.9 mm carapace length. E. latreillii produced up to 15886 embryos, and clutch size increased with maternal size. Initial egg size was large (0.162 mm3), and the embryo volume increase during the incubation period was 32 %. Brood mortality was substantial (83 %), and since egg volume increase could not compensate for the egg loss, average egg mass volume decreased considerably during embryogenesis. The average brood mass at laying accounted for 13 % of the maternal body mass (on a wet mass basis), and this value coincides with previous findings concerning energy allocation for egg production in other brachyuran crabs. In general, our data regarding E. latreillii correspond well with those from spider crab species inhabiting the northern hemisphere. The large egg size of E. latreillii compared with majids from other geographical regions may be an indication of a latitudinal gradient in the reproductive biology of majid crabs. Future studies with spider crabs from the southern hemisphere are desirable to substantiate this assumption.Se estudió la producción de huevos y la inversión reproductiva del cangrejo araña Eurypodius latreillii proveniente del Estrecho de Magallanes, sur de Chile. Se analizaron un total de 66 hembras ovígeras con un rango de tamaños entre 29,0 y 62,9 mm de longitud de caparazón. E. latreilli produjo hasta un máximo de 15886 embriones, y el número de huevos aumentó con el tamaño de la hembra. El tamaño inicial del huevo fue grande (0,162 mm3) y el aumento del volumen embrionario durante el período de incubación fue de 32 %. La mortalidad de huevos fue considerable (83 %), y como el aumento en el volumen de los huevos no pudo compensar la pérdida de huevos, el promedio del volumen de la masa de los huevos disminuyó de forma considerable durante la embriogénesis. La masa de huevos representó un 13 % de la masa corporal de la madre, y este valor coincide con observaciones previas sobre la asignación de energía para la producción de huevos en otros braquiuros. En general, nuestros datos sobre E. latreillii concuerdan con datos sobre especies del cangrejo araña del hemisferio norte. El tamaño grande de huevos de E. latreillii comparado con Majidae de otras regiones geográficas podría ser interpretado como una indicación de un gradiente latitudinal en la biología reproductiva de cangrejos májidos. Para corroborar esta interpretación se requerirían estudios futuros con cangrejos araña del hemisferio sur

Detecting event-related recurrences by symbolic analysis: Applications to human language processing

Quasistationarity is ubiquitous in complex dynamical systems. In brain dynamics there is ample evidence that event-related potentials reflect such quasistationary states. In order to detect them from time series, several segmentation techniques have been proposed. In this study we elaborate a recent approach for detecting quasistationary states as recurrence domains by means of recurrence analysis and subsequent symbolisation methods. As a result, recurrence domains are obtained as partition cells that can be further aligned and unified for different realisations. We address two pertinent problems of contemporary recurrence analysis and present possible solutions for them.Comment: 24 pages, 6 figures. Draft version to appear in Proc Royal Soc

Spin and Center of Mass in Axially Symmetric Einstein-Maxwell Spacetimes

We give a definition and derive the equations of motion for the center of mass and angular momentum of an axially symmetric, isolated system that emits gravitational and electromagnetic radiation. A central feature of this formulation is the use of Newman-Unti cuts at null infinity that are generated by worldlines of the spacetime. We analyze some consequences of the results and comment on the generalization of this work to general asymptotically flat spacetimes.Comment: 20 page

Microstructure and reconstitution of freeze-dried gum Arabic at a range of concentrations and primary drying temperatures

Freeze-drying is an energy intensive unit operation used for the production of dehydrated foods, such as instant coffee and dried fruits, and results in high sensorial, nutritional and reconstitution properties of the final products. Understanding the relationships between operating conditions and product quality is essential to design processes that are energy efficient, whilst producing high quality dried foods. In this work, the properties (microstructure and reconstitution) of freeze-dried gum arabic samples (with initial concentrations ranging between 20 and 60% solids by weight) were evaluated. The materials were dried at three different primary drying shelf temperatures, Ts (- 20, - 30 and - 40 ◦C). Sample temperatures recorded throughout freeze-drying were close to the pre-set Ts, with the exception of the 60% initial concentration system, where the sample was hotter than the shelf by 10–15 ◦C, in particular on increasing Ts. This was attributed to a combination of local temperature and pressure conditions that may have resulted in partial melting of the material. For the 20–50% systems, the properties of the freeze-dried materials were mainly affected by the initial concentration of the system, with increasing initial concentration generally resulting in lower porosities (ranging between 20 and 40%) and higher reconstitution times (ranging between 0.5 and 10min for 95% reconstitution). Pores were generally needle-shaped and <200 μm. Large (200–1800 μm), circular pores were observed in high initial concentration systems, and they were dominant in the microstructure of the freeze-dried 60% sample. The presence of these large bubbles was linked to the partial melting of the material, which enabled its expansion and puffing. For the 60% system, primary drying temperature had a profound effect on the properties of the freeze-dried solid, with samples dried at higher temperature showing higher porosity (e.g. 60–70% for Ts = -¬¬ 20◦C) and faster reconstitution rates (e.g. 3min for 95% reconstitution at Ts = - 20◦C). Overall, this study demonstrates the significance of formulation and shelf temperature on the porous structure of freeze-dried samples, which directly influences product performance

Microscopic analytical theory of a correlated, two-dimensional N-electron gas in a magnetic field

We present a microscopic, analytical theory describing a confined N-electron gas in two dimensions subject to an external magnetic field. The number of electrons N and strength of the electron-electron interaction can be arbitrarily large, and all Landau levels are included implicitly. A possible connection with the Integer and Fractional Quantum Hall Effects is proposed.Comment: The revised version contains minor changes to text. To be published in J. Phys: Condens. Mat

Electroencephalography Predicts Poor and Good Outcomes After Cardiac Arrest: A Two-Center Study.

The prognostic role of electroencephalography during and after targeted temperature management in postcardiac arrest patients, relatively to other predictors, is incompletely known. We assessed performances of electroencephalography during and after targeted temperature management toward good and poor outcomes, along with other recognized predictors. Cohort study (April 2009 to March 2016). Two academic hospitals (Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland; Mayo Clinic, Rochester, MN). Consecutive comatose adults admitted after cardiac arrest, identified through prospective registries. All patients were managed with targeted temperature management, receiving prespecified standardized clinical, neurophysiologic (particularly, electroencephalography during and after targeted temperature management), and biochemical evaluations. We assessed electroencephalography variables (reactivity, continuity, epileptiform features, and prespecified "benign" or "highly malignant" patterns based on the American Clinical Neurophysiology Society nomenclature) and other clinical, neurophysiologic (somatosensory-evoked potential), and biochemical prognosticators. Good outcome (Cerebral Performance Categories 1 and 2) and mortality predictions at 3 months were calculated. Among 357 patients, early electroencephalography reactivity and continuity and flexor or better motor reaction had greater than 70% positive predictive value for good outcome; reactivity (80.4%; 95% CI, 75.9-84.4%) and motor response (80.1%; 95% CI, 75.6-84.1%) had highest accuracy. Early benign electroencephalography heralded good outcome in 86.2% (95% CI, 79.8-91.1%). False positive rates for mortality were less than 5% for epileptiform or nonreactive early electroencephalography, nonreactive late electroencephalography, absent somatosensory-evoked potential, absent pupillary or corneal reflexes, presence of myoclonus, and neuron-specific enolase greater than 75 µg/L; accuracy was highest for early electroencephalography reactivity (86.6%; 95% CI, 82.6-90.0). Early highly malignant electroencephalography had an false positive rate of 1.5% with accuracy of 85.7% (95% CI, 81.7-89.2%). This study provides class III evidence that electroencephalography reactivity predicts both poor and good outcomes, and motor reaction good outcome after cardiac arrest. Electroencephalography reactivity seems to be the best discriminator between good and poor outcomes. Standardized electroencephalography interpretation seems to predict both conditions during and after targeted temperature management

Intoxicación accidental por paraíso (Melia azedarach) en bovinos

Fazzio, L.E.; Costa, E.F.; Streitenberger, N.; Pintos, M.E.; Quiroga, M.A.: Intoxicación accidental por paraíso (Melia azedarach) en bovinos. Rev. vet. 26: 1, 54-58, 201