940 resultados para quality function development


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Intestinal bacterial flora may induce splanchnic hemodynamic and histological alterations that are associated with portal hypertension (PH). We hypothesized that experimental PH would be attenuated in the complete absence of intestinal bacteria. We induced prehepatic PH by partial portal vein ligation (PPVL) in germ-free (GF) or mice colonized with altered Schaedler's flora (ASF). After 2 or 7 days, we performed hemodynamic measurements, including portal pressure (PP) and portosystemic shunts (PSS), and collected tissues for histomorphology, microbiology, and gene expression studies. Mice colonized with intestinal microbiota presented significantly higher PP levels after PPVL, compared to GF, mice. Presence of bacterial flora was also associated with significantly increased PSS and spleen weight. However, there were no hemodynamic differences between sham-operated mice in the presence or absence of intestinal flora. Bacterial translocation to the spleen was demonstrated 2 days, but not 7 days, after PPVL. Intestinal lymphatic and blood vessels were more abundant in colonized and in portal hypertensive mice, as compared to GF and sham-operated mice. Expression of the intestinal antimicrobial peptide, angiogenin-4, was suppressed in GF mice, but increased significantly after PPVL, whereas other angiogenic factors remained unchanged. Moreover, colonization of GF mice with ASF 2 days after PPVL led to a significant increase in intestinal blood vessels, compared to controls. The relative increase in PP after PPVL in ASF and specific pathogen-free mice was not significantly different. CONCLUSION In the complete absence of gut microbial flora PP is normal, but experimental PH is significantly attenuated. Intestinal mucosal lymphatic and blood vessels induced by bacterial colonization may contribute to development of PH.

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Several congenital syndromes associated with anterior segment (AS) anomalies can lead to impaired vision and glaucoma, such as nail-patella syndrome (NPS), caused by mutations in the LIM homeodomain transcription factor LMX1B and Axenfeld-Rieger's syndrome (ARS), caused by mutations in the bicoid-related homeodomain transcription factor PITX2. Targeted mutations in lmx1b and pitx2 and RNA in situ analysis reveal that both genes are required for AS development and are co-expressed within the periocular mesenchyme, suggesting they participate in a shared genetic pathway. Lmx1b homozygous mutants display iris and corneal stroma hypoplasia, and defects in ciliary body formation. In contrast, pitx2 homozygous mutants exhibit a more severe phenotype: the AS chamber, corneal endothelium, and extraocular muscles (EOM) fail to develop. The absence of EOM in pitx2 mutants suggests pitx2 acts upstream of lmx1b, or that other lmx1b family members, such as lmx1a, can compensate for lmx1b function. Lmxla/lmx1b double homozygous mutants have a reduced capacity to generate EOM, implying that lmx1 gene products have a redundant function in EOM development and that lmx1 family members may act downstream of pitx2. However, analysis of pitx2 expression in the AS tissues of lmx1b mutants and reciprocal studies of lmx1b expression in pitx2 mutants indicate that these genes do not function in a simple linear pathway. Instead, lmx1b and pitx2 may regulate a shared set of downstream targets or both genes may work in parallel transcribing unique targets required for a common biological process. Ultrastructural analysis of lmx1b and pitx2 mutant corneas indicates that collagen fibrillogenesis is perturbed, revealing a common role for both genes in the deposition of extracellular matrix. Furthermore, lmx1b/pitx2 double heterozygotes develop corneal opacities not observed in single heterozygotes demonstrating that lmx1b and pitx2 genetically interact. Data suggests that defects in the basement membrane of the corneal endothelium underlie the opacities observed in double heterozygotes. Additionally, double heterozygotes develop anterior synechias that occlude the trabecular meshwork, potentially blocking aqueous humor drainage. These data suggest that lmx1b and pitx2 are responsible for ECM deposition in multiple cell types and imply that such defects may contribute to the glaucomas observed in NPS and ARS patients. ^

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Complex molecular events underlie vertebrate eye development and disease. The eye is composed of two major tissue types: the anterior and posterior segments. During development, the retinal progenitor cells differentiate into six neuronal and one non-neuronal cell types. These cell types later organize into the distinct laminar structure of the mature retina which occupies the posterior segment. In the developed anterior segment, both the ciliary body and trabecular meshwork regulate intraocular pressure created by the aqueous humor. The disruption in intraocular pressure can lead to a blinding condition called glaucoma. To characterize molecular mechanisms governing retinal development and glaucoma, two separate mouse knockout lines carrying mutations in math5 and myocilin were subjected to a series of in vivo analyses. ^ Math5 is a murine homologue of Drosophila atonal , a bHLH proneural gene essential for the formation of photoreceptor cells. The expression of math5 coincides with the onset of retinal ganglion cell differentiation. The targeted deletion of mouse math5 revealed that a null mutation inhibits the formation of a majority of the retinal ganglion cells. The mutation also interferes with the normal development of other retinal cell types such as amacrine, bipolar and photoreceptor cells. These results suggest that math5 is a proneural gene responsible for differentiation of retinal ganglion cells and may also have a role in normal development of other neuronal cell types within the retina. ^ Myocilin has two unique protein coding regions bearing homology to non-muscle myosin of Dictyostelium discoideum and to olfactomedin, an extracellular matrix molecule first described in the olfactory epithelium of the bullfrog. Recently, autosomal dominant forms of myocilin mutations have been found in individuals with primary open-angle glaucoma. The genetic linkage to glaucoma suggests a role of myocilin in normal intraocular pressure and ocular function. However, the analysis of mice heterozygous and homozygous for a targeted null mutation in myocilin indicates that it is dispensable for normal intraocular pressure or ocular function. Additionally, the lack of a discernable phenotype in both heterozygous and null mice suggests that haploinsufficiency is not a critical mechanism for MYOC-associated glaucoma in humans. Instead, disease-causing mutations likely act by gain of function. ^ In summary, these studies provide novel insights into the embryonic development of the vertebrate retina, and also begin to uncover the molecular mechanisms responsible for the pathogenesis of glaucoma. ^

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The research study was intended to evaluate the effectiveness of Inner City Development's (I.C.D.) Cooperative Home School, an educational alternative program to the Title I public schools of San Antonio's West Side community. The study investigated students', parents' and tutors' perception of parental involvement and educational resources. The study also investigated each student's academic achievement. ^ The study found that students progressed toward expected math proficiency at a faster rate than they did in reading proficiency. However, because the target population size was small and a comparison group was not used, the results of this study are only suggestive. This research also indicated that study subjects believed students' quality and level of education increased substantially since program exposure. Study subjects mainly attributed the students' strides in academic performance to the increased amount of individualized attention students received in the small twelve-student class size. Study subjects were more satisfied with the home school's educational resources than those of the Title I public schools. Study subjects also perceived that parental involvement both at home and at school increased since enrollment in the home school program because: (1) there were more opportunities for involvement in the home school; and (2) parents felt closer to the tutors than the teachers in public school. ^ This evaluation also suggested improvements to program operations. With the help of additional volunteers, I.C.D. program operators could improve collection and organization of academic records. Furthermore, as suggested by program participants, science could be added to the curriculum. Lastly, a formal tutor orientation could be implemented to familiarize and train tutors on classroom management procedures. ^

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The Radiological Physics Center (RPC) uses both on-site and remote reviews to credential institutions for participation in clinical trials. Anthropomorphic quality assurance (QA) phantoms are one tool the RPC uses to remotely audit institutions, which include thermoluminescent dosimeters (TLDs) and radiochromic film. The RPC desires to switch from TLD as the absolute dosimeter in the phantoms, to optically stimulated luminescent dosimeters (OSLDs), but a problem lies in the angular dependence exhibited by the OSLD. The purpose of this study was to characterize the angular dependence of OSLD and establish a correction factor if necessary, to provide accurate dosimetric measurements as a replacement for TLD in the QA phantoms. A 10 cm diameter high-impact polystyrene spherical phantom was designed and constructed to hold an OSLD to study the angular response of the dosimeter under the simplest of circumstances for both coplanar and non-coplanar treatment deliveries. OSLD were irradiated in the spherical phantom, and the responses of the dosimeter from edge-on angles were normalized to the response when irradiated with the beam incident normally on the surface of the dosimeter. The average normalized response was used to establish an angular correction factor for 6 MV and 18 coplanar treatments, and for 6 MV non-coplanar treatments specific to CyberKnife. The RPC pelvic phantom dosimetry insert was modified to hold OSLD, in addition to the TLD, adjacent to the planes of film. Treatment plans of increasing angular beam delivery were developed, three in Pinnacle v9.0 (4-field box, IMRT, and VMAT) and one in Accuray’s MultiPlan v3.5.3 (CyberKnife). The plans were delivered to the pelvic phantom containing both TLD and OSLD in the target volume. The pelvic phantom was also sent to two institutions to be irradiated as trials, one delivering IMRT, and the other a CyberKnife treatment. For the IMRT deliveries and the two institution trials, the phantom also included film in the sagittal and coronal planes. The doses measured from the TLD and OSLD were calculated for each irradiation, and the angular correction factors established from the spherical phantom irradiations were applied to the OSLD dose. The ratio of the TLD dose to the angular corrected OSLD dose was calculated for each irradiation. The corrected OSLD dose was found to be within 1% of the TLD measured dose for all irradiations, with the exception of the in-house CyberKnife deliveries. The films were normalized to both TLD measured dose and the corrected OSLD dose. Dose profiles were obtained and gamma analysis was performed using a 7%/4 mm criteria, to compare the ability of the OSLD, when corrected for the angular dependence, to provide equivalent results to TLD. The results of this study indicate that the OSLD can effectively be used as a replacement for TLD in the RPC’s anthropomorphic QA phantoms for coplanar treatment deliveries when a correction is applied for the dosimeter’s angular dependence.

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1. Introduction 2. Air Quality Modeling system 3. Emission Inventories 4. Applications and Results 5. Conclusions

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Modeling is an essential tool for the development of atmospheric emission abatement measures and air quality plans. Most often these plans are related to urban environments with high emission density and population exposure. However, air quality modeling in urban areas is a rather challenging task. As environmental standards become more stringent (e.g. European Directive 2008/50/EC), more reliable and sophisticated modeling tools are needed to simulate measures and plans that may effectively tackle air quality exceedances, common in large urban areas across Europe, particularly for NO2. This also implies that emission inventories must satisfy a number of conditions such as consistency across the spatial scales involved in the analysis, consistency with the emission inventories used for regulatory purposes and versatility to match the requirements of different air quality and emission projection models. This study reports the modeling activities carried out in Madrid (Spain) highlighting the atmospheric emission inventory development and preparation as an illustrative example of the combination of models and data needed to develop a consistent air quality plan at urban level. These included a series of source apportionment studies to define contributions from the international, national, regional and local sources in order to understand to what extent local authorities can enforce meaningful abatement measures. Moreover, source apportionment studies were conducted in order to define contributions from different sectors and to understand the maximum feasible air quality improvement that can be achieved by reducing emissions from those sectors, thus targeting emission reduction policies to the most relevant activities. Finally, an emission scenario reflecting the effect of such policies was developed and the associated air quality was modeled.

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The plant cell wall constitutes an essential protection barrier against pathogen attack. In addition, cell-wall disruption leads to accumulation of jasmonates (JAs), which are key signaling molecules for activation of plant inducible defense responses. However, whether JAs in return modulate the cell-wall composition to reinforce this defensive barrier remains unknown. The enzyme 13-allene oxide synthase (13-AOS) catalyzes the first committed step towards biosynthesis of JAs. In potato (Solanum tuberosum), there are two putative St13-AOS genes, which we show here to be differentially induced upon wounding. We also determine that both genes complement an Arabidopsis aos null mutant, indicating that they encode functional 13-AOS enzymes. Indeed, transgenic potato plants lacking both St13-AOS genes (CoAOS1/2 lines) exhibited a significant reduction of JAs, a concomitant decrease in wound-responsive gene activation, and an increased severity of soft rot disease symptoms caused by Dickeya dadantii. Intriguingly, a hypovirulent D. dadantii pel strain lacking the five major pectate lyases, which causes limited tissue maceration on wild-type plants, regained infectivity in CoAOS1/2 plants. In line with this, we found differences in pectin methyl esterase activity and cell-wall pectin composition between wild-type and CoAOS1/2 plants. Importantly, wild-type plants had pectins with a lower degree of methyl esterification, which are the substrates of the pectate lyases mutated in the pel strain. These results suggest that, during development of potato plants, JAs mediate modification of the pectin matrix to form a defensive barrier that is counteracted by pectinolytic virulence factors from D. dadantii.

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As environmental standards become more stringent (e.g. European Directive 2008/50/EC), more reliable and sophisticated modeling tools are needed to simulate measures and plans that may effectively tackle air quality exceedances, common in large cities across Europe, particularly for NO2. Modeling air quality in urban areas is rather complex since observed concentration values are a consequence of the interaction of multiple sources and processes that involve a wide range of spatial and temporal scales. Besides a consistent and robust multi-scale modeling system, comprehensive and flexible emission inventories are needed. This paper discusses the application of the WRF-SMOKE-CMAQ system to the Madrid city (Spain) to assess the contribution of the main emitting sectors in the region. A detailed emission inventory was compiled for this purpose. This inventory relies on bottom-up methods for the most important sources. It is coupled with the regional traffic model and it makes use of an extensive database of industrial, commercial and residential combustion plants. Less relevant sources are downscaled from national or regional inventories. This paper reports the methodology and main results of the source apportionment study performed to understand the origin of pollution (main sectors and geographical areas) and define clear targets for the abatement strategy. Finally the structure of the air quality monitoring is analyzed and discussed to identify options to improve the monitoring strategy not only in the Madrid city but the whole metropolitan area.

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La mejora de la calidad del aire es una tarea eminentemente interdisciplinaria. Dada la gran variedad de ciencias y partes involucradas, dicha mejora requiere de herramientas de evaluación simples y completamente integradas. La modelización para la evaluación integrada (integrated assessment modeling) ha demostrado ser una solución adecuada para la descripción de los sistemas de contaminación atmosférica puesto que considera cada una de las etapas involucradas: emisiones, química y dispersión atmosférica, impactos ambientales asociados y potencial de disminución. Varios modelos de evaluación integrada ya están disponibles a escala continental, cubriendo cada una de las etapas antesmencionadas, siendo el modelo GAINS (Greenhouse Gas and Air Pollution Interactions and Synergies) el más reconocido y usado en el contexto europeo de toma de decisiones medioambientales. Sin embargo, el manejo de la calidad del aire a escala nacional/regional dentro del marco de la evaluación integrada es deseable. Esto sin embargo, no se lleva a cabo de manera satisfactoria con modelos a escala europea debido a la falta de resolución espacial o de detalle en los datos auxiliares, principalmente los inventarios de emisión y los patrones meteorológicos, entre otros. El objetivo de esta tesis es presentar los desarrollos en el diseño y aplicación de un modelo de evaluación integrada especialmente concebido para España y Portugal. El modelo AERIS (Atmospheric Evaluation and Research Integrated system for Spain) es capaz de cuantificar perfiles de concentración para varios contaminantes (NO2, SO2, PM10, PM2,5, NH3 y O3), el depósito atmosférico de especies de azufre y nitrógeno así como sus impactos en cultivos, vegetación, ecosistemas y salud como respuesta a cambios porcentuales en las emisiones de sectores relevantes. La versión actual de AERIS considera 20 sectores de emisión, ya sea equivalentes a sectores individuales SNAP o macrosectores, cuya contribución a los niveles de calidad del aire, depósito e impactos han sido modelados a través de matrices fuentereceptor (SRMs). Estas matrices son constantes de proporcionalidad que relacionan cambios en emisiones con diferentes indicadores de calidad del aire y han sido obtenidas a través de parametrizaciones estadísticas de un modelo de calidad del aire (AQM). Para el caso concreto de AERIS, su modelo de calidad del aire “de origen” consistió en el modelo WRF para la meteorología y en el modelo CMAQ para los procesos químico-atmosféricos. La cuantificación del depósito atmosférico, de los impactos en ecosistemas, cultivos, vegetación y salud humana se ha realizado siguiendo las metodologías estándar establecidas bajo los marcos internacionales de negociación, tales como CLRTAP. La estructura de programación está basada en MATLAB®, permitiendo gran compatibilidad con software típico de escritorio comoMicrosoft Excel® o ArcGIS®. En relación con los niveles de calidad del aire, AERIS es capaz de proveer datos de media anual y media mensual, así como el 19o valor horario más alto paraNO2, el 25o valor horario y el 4o valor diario más altos para SO2, el 36o valor diario más alto para PM10, el 26o valor octohorario más alto, SOMO35 y AOT40 para O3. En relación al depósito atmosférico, el depósito acumulado anual por unidad de area de especies de nitrógeno oxidado y reducido al igual que de azufre pueden ser determinados. Cuando los valores anteriormente mencionados se relacionan con características del dominio modelado tales como uso de suelo, cubiertas vegetales y forestales, censos poblacionales o estudios epidemiológicos, un gran número de impactos puede ser calculado. Centrándose en los impactos a ecosistemas y suelos, AERIS es capaz de estimar las superaciones de cargas críticas y las superaciones medias acumuladas para especies de nitrógeno y azufre. Los daños a bosques se calculan como una superación de los niveles críticos de NO2 y SO2 establecidos. Además, AERIS es capaz de cuantificar daños causados por O3 y SO2 en vid, maíz, patata, arroz, girasol, tabaco, tomate, sandía y trigo. Los impactos en salud humana han sido modelados como consecuencia de la exposición a PM2,5 y O3 y cuantificados como pérdidas en la esperanza de vida estadística e indicadores de mortalidad prematura. La exactitud del modelo de evaluación integrada ha sido contrastada estadísticamente con los resultados obtenidos por el modelo de calidad del aire convencional, exhibiendo en la mayoría de los casos un buen nivel de correspondencia. Debido a que la cuantificación de los impactos no es llevada a cabo directamente por el modelo de calidad del aire, un análisis de credibilidad ha sido realizado mediante la comparación de los resultados de AERIS con los de GAINS para un escenario de emisiones determinado. El análisis reveló un buen nivel de correspondencia en las medias y en las distribuciones probabilísticas de los conjuntos de datos. Las pruebas de verificación que fueron aplicadas a AERIS sugieren que los resultados son suficientemente consistentes para ser considerados como razonables y realistas. En conclusión, la principal motivación para la creación del modelo fue el producir una herramienta confiable y a la vez simple para el soporte de las partes involucradas en la toma de decisiones, de cara a analizar diferentes escenarios “y si” con un bajo coste computacional. La interacción con políticos y otros actores dictó encontrar un compromiso entre la complejidad del modeladomedioambiental con el carácter conciso de las políticas, siendo esto algo que AERIS refleja en sus estructuras conceptual y computacional. Finalmente, cabe decir que AERIS ha sido creado para su uso exclusivo dentro de un marco de evaluación y de ninguna manera debe ser considerado como un sustituto de los modelos de calidad del aire ordinarios. ABSTRACT Improving air quality is an eminently inter-disciplinary task. The wide variety of sciences and stakeholders that are involved call for having simple yet fully-integrated and reliable evaluation tools available. Integrated AssessmentModeling has proved to be a suitable solution for the description of air pollution systems due to the fact that it considers each of the involved stages: emissions, atmospheric chemistry, dispersion, environmental impacts and abatement potentials. Some integrated assessment models are available at European scale that cover each of the before mentioned stages, being the Greenhouse Gas and Air Pollution Interactions and Synergies (GAINS) model the most recognized and widely-used within a European policy-making context. However, addressing air quality at the national/regional scale under an integrated assessment framework is desirable. To do so, European-scale models do not provide enough spatial resolution or detail in their ancillary data sources, mainly emission inventories and local meteorology patterns as well as associated results. The objective of this dissertation is to present the developments in the design and application of an Integrated Assessment Model especially conceived for Spain and Portugal. The Atmospheric Evaluation and Research Integrated system for Spain (AERIS) is able to quantify concentration profiles for several pollutants (NO2, SO2, PM10, PM2.5, NH3 and O3), the atmospheric deposition of sulfur and nitrogen species and their related impacts on crops, vegetation, ecosystems and health as a response to percentual changes in the emissions of relevant sectors. The current version of AERIS considers 20 emission sectors, either corresponding to individual SNAP sectors or macrosectors, whose contribution to air quality levels, deposition and impacts have been modeled through the use of source-receptor matrices (SRMs). Thesematrices are proportionality constants that relate emission changes with different air quality indicators and have been derived through statistical parameterizations of an air qualitymodeling system (AQM). For the concrete case of AERIS, its parent AQM relied on the WRF model for meteorology and on the CMAQ model for atmospheric chemical processes. The quantification of atmospheric deposition, impacts on ecosystems, crops, vegetation and human health has been carried out following the standard methodologies established under international negotiation frameworks such as CLRTAP. The programming structure isMATLAB ® -based, allowing great compatibility with typical software such as Microsoft Excel ® or ArcGIS ® Regarding air quality levels, AERIS is able to provide mean annual andmean monthly concentration values, as well as the indicators established in Directive 2008/50/EC, namely the 19th highest hourly value for NO2, the 25th highest daily value and the 4th highest hourly value for SO2, the 36th highest daily value of PM10, the 26th highest maximum 8-hour daily value, SOMO35 and AOT40 for O3. Regarding atmospheric deposition, the annual accumulated deposition per unit of area of species of oxidized and reduced nitrogen as well as sulfur can be estimated. When relating the before mentioned values with specific characteristics of the modeling domain such as land use, forest and crops covers, population counts and epidemiological studies, a wide array of impacts can be calculated. When focusing on impacts on ecosystems and soils, AERIS is able to estimate critical load exceedances and accumulated average exceedances for nitrogen and sulfur species. Damage on forests is estimated as an exceedance of established critical levels of NO2 and SO2. Additionally, AERIS is able to quantify damage caused by O3 and SO2 on grapes, maize, potato, rice, sunflower, tobacco, tomato, watermelon and wheat. Impacts on human health aremodeled as a consequence of exposure to PM2.5 and O3 and quantified as losses in statistical life expectancy and premature mortality indicators. The accuracy of the IAM has been tested by statistically contrasting the obtained results with those yielded by the conventional AQM, exhibiting in most cases a good agreement level. Due to the fact that impacts cannot be directly produced by the AQM, a credibility analysis was carried out for the outputs of AERIS for a given emission scenario by comparing them through probability tests against the performance of GAINS for the same scenario. This analysis revealed a good correspondence in the mean behavior and the probabilistic distributions of the datasets. The verification tests that were applied to AERIS suggest that results are consistent enough to be credited as reasonable and realistic. In conclusion, the main reason thatmotivated the creation of this model was to produce a reliable yet simple screening tool that would provide decision and policy making support for different “what-if” scenarios at a low computing cost. The interaction with politicians and other stakeholders dictated that reconciling the complexity of modeling with the conciseness of policies should be reflected by AERIS in both, its conceptual and computational structures. It should be noted however, that AERIS has been created under a policy-driven framework and by no means should be considered as a substitute of the ordinary AQM.

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Con esta tesis doctoral se pretende elaborar un modelo de Certificado de Calidad Cinegética independiente, de adhesión voluntaria y aplicable a todo tipo de espacios cinegéticos, de forma que posteriormente pueda convertirse en una metodología que sea empleada como instrumento válido de medición de la Calidad Cinegética y normalizada a través de una familia de Normas aprobadas por un organismo de normalización reconocido a nivel nacional o internacional. En primer lugar, se procedió a la realización de un riguroso y exhaustivo estudio de justificación siguiendo la metodología propuesta por la Norma UNE 66172:2003 IN, Directrices para la justificación y desarrollo de sistemas de gestión (equivalente a la Norma Internacional GUIA ISO/IEC 72:2001). A continuación, se procedió a la identificación y desarrollo de los parámetros de Ordenación Cinegética comunes a cualquier espacio cinegético en España y a la conceptualización de la Calidad Cinegética. Finalmente, se desarrolló un modelo estructurado en nueve Criterios y treinta y cuatro Indicadores de Calidad Cinegética, y un proyecto de familia de Normas para la Certificación de la Calidad Cinegética. ABSTRACT This doctoral thesis aims to produce a model of Hunting Quality Certificate independent, of voluntary adherence and applicable to all types of hunting areas, so that later it can become a methodology to be used as a valid instrument for measuring Hunting Quality and standardized through a family of standards approved by an organization of standardization recognized at a national or an international level. First, we proceeded to carry out a rigorous and comprehensive justification study following the methodology proposed by the UNE 66172: 2003 IN, Guidelines for the justification and development of management systems standards (equivalent to the International Standard GUIA ISO / IEC 72: 2001). Then, we proceeded to the identification and development of Hunting Management parameters common to any hunting area in Spain and the conceptualization of Hunting Quality. Finally, a model structured into nine Criteria and thirty-four Indicators of Hunting Quality and a draft of a family of standards for Hunting Quality Certification were developed.

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Vertebrate limb tendons are derived from connective cells of the lateral plate mesoderm. Some of the developmental steps leading to the formation of vertebrate limb tendons have been previously identified; however, the molecular mechanisms responsible for tendinous patterning and maintenance during embryogenesis are largely unknown. The eyes absent (eya) gene of Drosophila encodes a novel nuclear protein of unknown molecular function. Here we show that Eya1 and Eya2, two mouse homologues of Drosophila eya, are expressed initially during limb development in connective tissue precursor cells. Later in limb development, Eya1 and Eya2 expression is associated with cell condensations that form different sets of limb tendons. Eya1 expression is largely restricted to flexor tendons, while Eya2 is expressed in the extensor tendons and ligaments of the phalangeal elements of the limb. These data suggest that Eya genes participate in the patterning of the distal tendons of the limb. To investigate the molecular functions of the Eya gene products, we have analyzed whether the highly divergent PST (proline-serine-threonine)-rich N-terminal regions of Eya1–3 function as transactivation domains. Our results demonstrate that Eya gene products can act as transcriptional activators, and they support a role for this molecular function in connective tissue patterning.

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The β-adrenergic receptor kinase 1 (βARK1) is a member of the G protein-coupled receptor kinase (GRK) family that mediates the agonist-dependent phosphorylation and desensitization of G protein-coupled receptors. We have cloned and disrupted the βARK1 gene in mice by homologous recombination. No homozygote βARK1−/− embryos survive beyond gestational day 15.5. Prior to gestational day 15.5, βARK1−/− embryos display pronounced hypoplasia of the ventricular myocardium essentially identical to the “thin myocardium syndrome” observed upon gene inactivation of several transcription factors (RXRα, N-myc, TEF-1, WT-1). Lethality in βARK1−/− embryos is likely due to heart failure as they exhibit a >70% decrease in cardiac ejection fraction determined by direct in utero intravital microscopy. These results along with the virtual absence of endogenous GRK activity in βARK1−/− embryos demonstrate that βARK1 appears to be the predominant GRK in early embryogenesis and that it plays a fundamental role in cardiac development.

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Calcium permeability of l-α-amino-3-hydroxy-5-methyl-4-isoxazolepropionate receptors (AMPARs) in excitatory neurons of the mammalian brain is prevented by coassembly of the GluR-B subunit, which carries an arginine (R) residue at a critical site of the channel pore. The codon for this arginine is created by site-selective adenosine deamination of an exonic glutamine (Q) codon at the pre-mRNA level. Thus, central neurons can potentially control the calcium permeability of AMPARs by the level of GluR-B gene expression as well as by the extent of Q/R-site editing, which in postnatal brain, positions the R codon into >99% of GluR-B mRNA. To study whether the small amount of unedited GluR-B is of functional relevance, we have generated mice carrying GluR-B alleles with an exonic arginine codon. We report that these mutants manifest no obvious deficiencies, indicating that AMPAR-mediated calcium influx into central neurons can be solely regulated by the levels of Q/R site-edited GluR-B relative to other AMPAR subunits. Notably, a targeted GluR-B gene mutant with 30% reduced GluR-B levels had 2-fold higher AMPAR-mediated calcium permeability in hippocampal pyramidal cells with no sign of cytotoxicity. This constitutes proof in vivo that elevated calcium influx through AMPARs need not generate pathophysiological consequences.