OALib Journal期刊

ISSN: 2333-9721




2019 ( 3 )

2018 ( 31 )

2017 ( 24 )

2016 ( 49 )


匹配条件: “González-Pech” ,找到相关结果约26375条。
Caracterización de la ingestión por observación directa en reba?os ovinos del Sureste de Francia
González-Pech,P.; Agreil,C.;
Archivos de Zootecnia , 2012, DOI: 10.4321/S0004-05922012000300003
Abstract: when ruminants graze on heterogeneous vegetation, direct observation of bites is one of the most fitted method to estimate intake. nevertheless its implementation in herds of more than 500 individuals has been scarce. in our study, this method was implemented to characterize the intake and know the feeding value offered by steppe vegetation. we observed two ovine flocks of 1100 and 1200 animals guided by shepherds in farm conditions. the animals used were merinos d'arles a breed with marked gregariousness. they constitute transhumant flocks that every spring graze the steppe vegetation of the nature reserve coussouls de crau located in southeast france. the period of adaptation was brief lasting from 7 to 22 days. in this environment composed of a unique herbaceous layer, the intake rate was 5.9 ± 2.4 g dm/min, which is similar to levels reported in woody or shrubby rangelands. we found that in this steppe vegetation sheep are capable of flows up to 13 g dm/min. in previous studies the brachypodium retusum has been considered of low nutritional value and little appreciated by the sheep. in our case it was found that the sheep eat a wide variety of plants. but when brachypodium retusum contributes to the majority of dry matter intake, intake rate is significantly greater (6.8 g dm/ min) than when this is contributed by forbs (4.4 g dm/min) or by the other grasses (5.8 g dm/min). this plant is revalued, our results showed that it allows sheep to make bites of mass higher than forbs and other grasses which explains its improved efficiency of collection. direct observation allowed us to characterize the intake of sheep in crau steppe and we consider this type of vegetation as a food source similar to woody or shrubby rangelands.
Andrés Pech Pérez,Carlos 0. Jiménez González,Martín Cárdenas Soto
Revista de Ingeniería Sísmica , 2010,
Abstract: En este trabajo, se usa la técnica conocida como interferometría sísmica para caracterizar la respuesta sísmica de los sitios donde se ubican las estaciones: Chapultepec, Kennedy y Roma. La estimación de parámetros se efectuó mediante la deconvolución de eventos sísmicos. Para interpretar los registros deconvolucionados, se utilizó un modelo de un medio estratificado compuesto por estratos elásticos, isótropos y homogéneos. En este modelo se consideró la incidencia vertical de ondas planas SH. De los registros deconvolucionados, se obtuvieron velocidades de propagación de ondas S. Con estos parámetros fue posible caracterizar los sitios donde se ubican las estaciones: Chapultepec, Kennedy y Roma. En los registros deconvolucionados, se observaron variaciones en amplitudes y tiempos de arribo en función del evento sísmico; esto sugiere que es posible identificar cambios en las propiedades físicas del suelo del Valle de México mediante interferometría sísmica.
Some New Questions about the Seasonal Decrease of the Ozone Layer  [PDF]
Jaime González Velasco
Green and Sustainable Chemistry (GSC) , 2012, DOI: 10.4236/gsc.2012.23016
Abstract: The depletion-recovery cycle of the ozone layer is explained on the basis of the magnetic properties of oxygen, ozone, nitrogen oxides and chlorine combinations, which upon interaction with the Earth’s magnetic field, give rise to gaseous fluxes polar- and equatorial-wards.
What Does “Noise Pollution” Mean?  [PDF]
Alice Elizabeth González
Journal of Environmental Protection (JEP) , 2014, DOI: 10.4236/jep.2014.54037

Noise features different characteristics that make it different from every other “classic” pollutant. Noise is invisible; it does not smell; it disappears when the source is turned off and leaves no traces in the environment. In addition, when people perceive something wrong about their hearing capacity, it is often long time after the beginning of noise exposure. This fact contributes to strengthening the misconception that noise is not harmful to human health or, at least, efforts and funds aim preferably at controling and decreasing the emission of other pollutants. Adding to this, most people tend to consider that noise is the price to pay for accessing to the amenities of the Technological Era and it is indivisible and inevitably linked to them. Last but not least, noise pollution could adversely affect ecosystems and ecological services. Then, how is it possible to convince the decision makers that noise pollution is one of the major current environmental problems? The aim of this paper is to discuss step by step the applicability of noise of a “pollution” definition, as a way to ease the understanding that lowering environmental noise levels should be prioritized: because it will lead to a healthier and better society.

Some Ideas about the Thermal Equilibrium in the Biosphere and the Entropy Variation Ascribed to Changes in the Radiations Wavelengths  [PDF]
Jaime González Velasco
Open Journal of Physical Chemistry (OJPC) , 2015, DOI: 10.4236/ojpc.2015.54011
Abstract: An explanation is given for the thermal equilibrium in the biosphere, which is based in the equality between the thermal energy received from the sun and the thermal energy reemitted from the atmosphere to the space. In order to understand the origin of the energy that gives rise to the processes and phenomena taking place in the biosphere, it is necessary to take into account the free energy represented by the product of temperature times the change in entropy, T△S, whose magnitude can be attributed to the variation experimented by the wavelengths (or, consequently, the frequencies) of the radiations composing the radiation spectrum received from the sun compared with the radiation spectrum reemitted from the biosphere into the space. A simple discussion allows to predict that the entropy increase driving the processes is connected with a spontaneous conversion of high frequency radiations (with lower “content” of entropy) in radiations of lower frequencies (with higher “content” of entropy). A consequence of this is that high frequency radiations would correspond to more ordered states and, therefore, to less probable states than those corresponding to radiations of lower frequencies.
The Gould's Belt Very Large Array Survey II: The Serpens region
Gisela N. Ortiz-León,Laurent Loinard,Amy J. Mioduszewski,Sergio A. Dzib,Luis F. Rodríguez,Gerardo Pech,Juana Rivera,Rosa M. Torres,Andrew Boden,Lee W. Hartmann,Neal J. Evans,Cesar Brice?o II,John J. Tobin,Marina A. Kounkel,Rosa A. González-Lópezlira
Physics , 2015, DOI: 10.1088/0004-637X/805/1/9
Abstract: We present deep ($\sim 17~\mu$Jy) radio continuum observations of the Serpens molecular cloud, the Serpens south cluster, and the W40 region obtained using the Very Large Array in its A configuration. We detect a total of 146 sources, 29 of which are young stellar objects (YSOs), 2 are BV stars and 5 more are associated with phenomena related to YSOs. Based on their radio variability and spectral index, we propose that about 16 of the remaining 110 unclassified sources are also YSOs. For approximately 65% of the known YSOs detected here as radio sources, the emission is most likely non-thermal, and related to stellar coronal activity. As also recently observed in Ophiuchus, our sample of YSOs with X-ray counterparts lies below the fiducial G\"udel & Benz relation. Finally, we analyze the proper motions of 9 sources in the W40 region. This allows us to better constrain the membership of the radio sources in the region.
Modeling of the Water Table Level Response Due to Extraordinary Precipitation Events: The Case of the Guadalupe Valley Aquifer  [PDF]
Javier González Ramírez, Rogelio Vázquez González
International Journal of Geosciences (IJG) , 2013, DOI: 10.4236/ijg.2013.46088

A two-dimensional algorithm for underground water flow simulation was modified and adapted to the geohydrologic conditions of the Guadalupe valley located in the state of Baja California in northern México. In order to solve the numerical model using the balance equation, the central finite differences with spatial and temporal constant increments method were used. Such model considers a heterogeneous and transient unconfined aquifer. Modeling and calibration processes are presented using the data of water table levels provided by the water level data loggers installed in a monitoring network and precipitation data from climatic stations of both seasons: 2009-2010 and 2010-2011. It was possible to locate, correlate and model specific rainfall-recharge events with the aim of obtaining an estimation of how these events are directly reflected on the water table level of the aquifer and how it reacts against simulated extraordinary events.

Thermodynamic and Dynamic of Chromium Biosorption by Pectic and Lignocellulocic Biowastes  [PDF]
Luis Sala, Juan González
Journal of Water Resource and Protection (JWARP) , 2010, DOI: 10.4236/jwarp.2010.210106
Abstract: Orange peel (OP) and rice husk (RH) were tested as low-cost biosorbents for Cr(III) removal from aqueous solutions. Dynamics of the biosorption process indicated that intraparticle mass transfer represents the rate-limiting step in the system that attained equilibrium at 120 min. While the OP sorbent material was capable of taking up 39.11 mg Cr(III)/g at the optimum pH 4.4, RH immobilized 3.20 mg Cr(III)/g at the optimum pH 3.0. The fitting of different sorption isotherms models resulted in the best fit with the Langmuir isotherm model. The mean free energy of the metal sorption process was in the range of 8-16 kJ/M. Abiotic Cr(VI) reduction was observed at various contact times and Cr-laden biomass was characterized by XPS, XAFS and EPR spectroscopy. These instrumental analyses confirmed that Cr(VI) removed from the solution was reduced and bound to the biomass as Cr(III). Results indicated that OP and RH materials are efficient biosorbents for eliminating Chromium from aqueous solutions.
Revisión y renovación de la sociología de la familia
Noé González
Espacio Abierto , 2009,
Bauman, identidad y comunidad
Noé González
Espiral , 2007,

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