Physical and chemical alteration of Distichlis spicata L. cell walls with NaCl and water stress

1991 Summer.Covers not scanned.Includes bibliographical references.Cultured cells of the halophytic grass Distichlis spicata adapted to grow in 500 mM NaCl (-25 bar) exhibited an altered growth physiology that resulted in slightly slower cell expansion and fully expanded cells with volumes only one-half to one-third those of unadapted cells. The reduced cell volume occurred despite maintenance of turgor pressures sometimes 2-fold higher than those of unadapted cells. Tensile strength as measured by a nitrogen gas decompression technique showed empirically that walls of NaCl-adapted cells were weaker than those of unadapted cells. Correlated with this weakening was a substantial change in the organization of the matrix polysaccharides; specifically, glucuronoarabinoxylan was more readily extractable, perhaps caused by a decrease in cross-linkages with phenol substances. Despite a 3-fold decrease in the amount of hydroxyproline and approximately a 2-fold increase in tyrosine, the quantity of insoluble protein and, the proportions of crystalline cellulose remained relative constant. Glycosidic linkage analysis of carbohydrates revealed little modification in the quantity and primary structure of the matrix polysaccharides as a result of NaCl (salinity) and polyethylene glycol 8000 (water deficit) stress. The study revealed that changes in the superstructure of glucuronoarabinoxylan are the primary determinant in the tensile strength of NaCl-adapted cells

Impact of Policy Scenarios in Irrigated Agriculture of River Guadalquivir Basin (Southern Spain)

This paper integrates indicators of environmental, social and economic impact of a range of policy scenarios through the use of Multicriteria and Multiperiod Programming. The case study is irrigated agriculture in the basin of the River Guadalquivir, and the policy scenarios combined Common Agricultural Policy and Water Framework Directive implementation in the period 2001-2010. The model is applied to a representative number of farming systems that attempt to offer a satisfactory description of the productive diversity of the basin. Results indicate that there are significant differences in the impact in the three dimensions (environmental, social and economic), according to the possible evolution of policy, market and technical futures. We believe that the integration of indicators into multicriteria models is a powerful system for building policy support tools for sounder decision making in the implementation of a future normative which will affect agricultural production in Europe, and that these tools can be used to deal with new questions that face agriculture (genetically modified organisms, new CAP, etc.)agricultural scenarios, indicators of sustainability, multicriteria models, multiperiod programming, Agricultural and Food Policy,

An Overview of Transfer Conditions: Exploring Latino Community College Students in Texas

This paper begins exploring the transfer conditions for Latino community college students in Texas. We provide an overview of the high school schooling conditions for Latinos; the experiences of Latinos in the community college; and some models that can increase the transfer and graduation rates for Latina/o community college students.Educatio

Comercio informal: un estudio en el municipio de Texcoco, Edo. de México

El objetivo de esta investigación fue realizar un análisis socioeconómico de los tianguistas en la ciudad de Texcoco, México; con el fin de identificar los factores que orillan a las personas al comercio informal bajo el enfoque de cuatro teorías. El análisis se llevó a cabo mediante las técnicas de la estadística descriptiva y las historias de vida. El estudio reveló que el 44% de los entrevistados incursionan en el ambulantaje por la falta de empleo, un 26% lo atribuye al bajo nivel de estudios y un 13% por no tener las competencias laborales y profesionales. Se encontró que los comerciantes informales de las edades entre 40 y 50 años de edad tienen un nivel básico de estudios (primaria) y los que oscilan entre 18 y 30 años de edad cuentan con secundaría y preparatoria, un problema que el Gobierno Federal y Estatal deberá atender, porque cada vez más jóvenes están participando en la economía informal del país

Successful medical management of an epidural abscess in a dog

A seven-month-old entire male dobermann presented with acute onset neck pain and left thoracic limb lameness. The dog had a similar episode eight weeks before presentation that responded to meloxicam. A cervical spinal epidural abscess secondary to Staphylococcus pseudintermedius bacteraemia was diagnosed following investigations, including MRI of the cervical vertebral column and blood cultures. Treatment with cephalexin, gabapentin and meloxicam was started. The dog was doing clinically well one month later. A control MRI and radiographs of the cervical vertebral column showed evidence of discospondylitis and resolution of the primary lesion, therefore the treatment course with cephalexin was continued. Three months after initial presentation the clinical signs had resolved, radiographs showed improvement of the discospondylitis and antibiotics were stopped. Seven months later the dog continued doing well with no relapse

Ecohydrology of aspen and eucalyptus plantations: considerations for management

Forecast scenarios predict an increase in the demand of alternative sources of energy during the coming decades, such as woody biomass crops (WBC). WBC have the potential to become a major challenge for the next generation of researchers, policymakers and land managers. However, the current rationale for promoting plant-based over petroleum-based energy sources emphasizes the benefits of reduced carbon dioxide and other emissions, while giving less attention to potential impacts to water resources. It is well documented in the scientific literature that trees use large amounts of water for metabolic needs. Water use at the tree and ecosystem level has always been of scientific interest, however, the potential impact of water use in bioenergy plantations is often considered a “possible environmental impact”. Thus, understanding the ecological implications of water use in WBC is essential for their sustainable development. The general goal of my research was to assess potential ecohydrological impacts associated with the production of biomass for bioenergy from aspen (Populus tremuloides Mich.) in Wisconsin, USA, and eucalyptus (Eucalyptus grandis) plantations in Entre Rios, Argentina. My doctoral research was part of a large international interdisciplinary NSF-PIRE research project that examined the impacts, barriers and opportunities related to bioenergy production across the Americas (USA, Mexico, Brazil, Argentina). We selected plantation ages within the most common rotation cycles for each species. In Wisconsin, we studied three sites, a 10- and a 24-year-old (YO) coppice plantations, and a reference 34 YO mature forest. In Argentina, we studied two 1 YO plantations one at high and one at regular density, a 4 YO, a 10 YO plantation, and a reference grassland. This was a unique study to determine annual water use based on a combination of tree-level measurements of water use using sap flow sensors, and deterministic models of potential evapotranspiration. We validated two sap flow methods (heat dissipation and heat ratio), and validated a third method (maximum heat ratio) that is capable of measuring with precision high and low sap flux densities (Fd, cm3 cm-2 cm1). According to the results from the validation studies, we were able to estimate tree-level water use within a 7% error margin (estimated as the difference between observed and estimated sap flow in L h-1) using heat ratio and maximum heat ratio methods, without generating species-specific parameters. However, using the heat dissipation method, the average estimation error without species-specific parameters was -53%, and improved to 5% once species-specific parameters were generated. Validating the maximum heat ratio method, allowed us to estimate Fd in young trees, which are often excluded from chronosequence studies due to their high Fd. Our estimates of Fd at different plantation ages, allowed us to extrapolate from the tree to the site level, using real tree-level response to various environmental variables. Our analysis of P. tremuloides and E. grandis offered contrasting results. In P. tremuloides plantations, water use at the site level generally increased with age, even when site density decreased over time (from approx. 6500 to 1900 from 10 to 34 YO). We observed that young plantations (10 YO) used 80% of the annual water early in the growing season, compared to a 45% for the same period in the Mid-aged and Mature plantations. Site effects, specifically soil type and the resulting soil saturation (S), had a significant effect on T estimates. After modeling the effects of S, creating two artificial scenarios (e.g. limited and non-limited S) the 10 YO site showed the highest sensibility to changes in S, while the 34 YO mature site was the least affected. Average stand transpiration by site considering the effects of S increased with age, which supported our hypothesis regarding the relationship between stand age and stand T. However, the relationship between stand T was not constant across seasons, which according to our results might be caused by a higher hydraulic stress observed in the 10YO site, compared to the other two sites. On eucalyptus plantations, when the density remained constant, stand T decreased with plantation age, reaching maximum water use rates at around 4 YO and declining afterwards for the remainder of the typical 15 YO rotation cycles. Due to similar site conditions in terms of soil characteristics, we did not observe a strong site effect. Our experimental site at high density (e.g., double of a regular site) showed an increase in average site T of 50%, and both 1 YO sites presented an opportunistic pattern in water use, increasing when soil water was available, but decreasing significantly when soil moisture was limiting. Finally, in both plantations we observed that reference evapotranspiration, estimated with the Penman-Monteith equation, was a poor predictor of water use in young plantations. We associate these results to the seasonal patterns of water use in young plantations. Within the context of bioenergy production, our results provide ample evidence for the importance of water use in bioenergy plantations in the early stages of feedstock production. We also show that plantation density in fast and slow growing species, impacts the way trees respond to water availability in the soil

Soil moisture dynamics in agriculturally-dominated landscapes after the introduction of native prairie vegetation

The effects of the establishment of strips of native prairie vegetation (SNPV) in agricultural fields on soil water dynamics and depth of plant water uptake by annual (ROWCROP) and perennial vegetation were studied. Soil water storage (SWS) was monitored biweekly to a depth of 100 cm during the growing seasons of 2007, 2008, 2009 and 2010 and differences were analyzed by land cover, topographic position and season primarily. Depth of water uptake (DWU) was assessed during the growing season of 2010 in four prairie species (Ratibida pinnata, Bromus ciliatus, Elymus canadensis, and Andropogon gerardii), and one crop species (Zea mays). DWU was analyzed by species, topographic position, photosynthetic pathway (C3 or C4), and by soil moisture available in the topsoil. DWU was assessed using stable isotopes of oxygen δ18O and hydrogen δD, and a calibration process was developed for vacuum cryogenic distillation to extract water from clay rich soils for isotopic analysis. Our results indicated that SWS was lower under prairie vegetation than ROWCROP after one year of establishment of the SNPV, with differences among land covers more pronounced in the first 30 cm of soil. During years of low and high precipitation the differences in SWS among land covers were minimal, which leads us to propose a threshold effect. Our data indicates that all species obtained water from the first 70 cm of soil. DWU was not influenced by the relative topographic position of individual plants but was influenced by the soil moisture available in the topsoil. Analyzed by photosynthetic pathway, C3 plants showed more sensitivity to changes in soil moisture, shifting to deeper depths than C4 when soil moisture was limiting in the topsoil

Proceso de producción de encurtido mixto en la Fábrica de Alimentos “La Matagalpa”, año 2012

El presente trabajo expone el estudio realizado en la Fábrica de alimentos “La Matagalpa” sobre el proceso de producción y especialmente enfocado en la elaboración de encurtido mixto con el propósito de analizar las etapas para su elaboración con el fin de determinar las principales debilidades existentes y poder brindar recomendaciones a la empresa. Este análisis se ha centrado en estudiar a fondo el proceso de elaboración que se realiza dentro de las instalaciones para este producto, teniendo como fundamento las normas aplicables de las Buenas Prácticas de Manufactura (BPM) para elaborar un producto final con calidad y que satisfaga las necesidades del cliente. Actualmente la empresa cuenta con procesos manuales para la elaboración de encurtido, aunque a pesar de ello se logra cumplir con la demanda regular a excepción de ciertas temporadas del año, además de contar con instalaciones que podrían mejorarse para una mejor condición laboral e higiene durante el trabajo, sin embargo existe procesos tecnológicos que permiten desarrollar este producto de manera higiénica cumpliendo con las normas exigidas. A pesar de contar con un sistema de gestión de calidad para inspeccionar las distintas etapas del proceso existen ciertas deficiencias que de una u otra manera podrían afectar el proceso en conjunto, por ello se recomienda tomar en cuenta los aspectos mencionados en la guía de recomendaciones las cuales están basadas en los puntos considerados como debilidades dentro de la empresa y que pueden ser modificados para una mejor producció