Estabilización de las subrasantes loéssicas utilizando el descarte de piedras ornamentales

El trabajo consiste en determinar el porcentaje óptimo de la dosificación del descarte proveniente de los telares de los aserraderos de rocas metamórficas e ígneas ornamentales cordobesas, mezclado con, los sedimentos inorgánicos de la planicie loéssicos erodable de la región mediterránea de la Argentina. Dicha dosificación, a punta a estabilizar química y mecánicamente, las subrasantes no pavimentadas en caminos terciarios con insuficiente bombeo transversal o drenaje lateral de cunetas. Generalmente, son vías de uso estacionales con un tránsito netamente agropecuario y, por ende presentan un escaso a nulo mantenimiento de la superficie de rodamiento; manifestandose, como consecuencia, una disminución paulatina de la resistencia al corte no drenada (Su) como, de la presión soporte (CBR 2,5mm) en cada intercalación anual de precipitaciones y sequias. Por ende, la estabilización del loess erodable con el porcentaje óptimo del descarte a determinar, logra garantizar un incremento de los valores de Su y CBR 2,5mm.en las subrasantes no pavimentadas estudiadas; siendo así optimizado el manteamiento de la superficie de rodamiento en al menos un periodo de precipitaciones y sequias.En general los ensayos geotécnicos realizados en el laboratorio de suelos y materiales de Universidad Católica de Córdoba (UCC) que garantizan dichos objetivos, son: contenido de humedad, lavado tamiz Nº 200, ensayos granulométricos, límites de Atterberg, doble hidrómetro, superficie específica, proctor estándar, compresión simple y California Bearing Ratio

Determinación de la distribución espacial de la humedad y altura de tortas de filtración mediante mediciones según un diseño nohlc

En un proceso de filtración se producen básicamente dos corrientes: el filtrado y la torta de filtración. La altura y la humedad remanente de la torta son parámetros que habitualmente se miden en ella. En general las tortas de filtrado no son constantes en su altura y humedad puntual sobre toda su área por efectos de borde de cámara, puntos de alimentación, desgaste de diafragmas etc., aunque es común que estos parámetros se midan en un punto próximo al centro, sin prestar atención a estas diferencias. El objetivo del trabajo es estandarizar una forma de medición rápida y precisa de estos parámetros. Para ello se deben conocer los perfiles de altura y humedad, para poder elegir un mínimo de sitios de muestreo que aseguren la representatividad del valor medido. Las tortas se obtuvieron por filtración de una suspensión de un concentrado de sulfuro metálico obtenido por flotación espumante, utilizando un filtro Larox PF 0,1 por presión, en escala piloto. Se realizaron tres ensayos, obteniendo tortas de 35,7 cm de diámetro. Para definir estos perfiles es necesario realizar un número considerable de tomas de muestra. Para definir los sitios de muestreo se usó un diseño NOHLC (Hiper Cubos Latinos Cuasi Ortogonales), aproximadamente ortogonal en dos variables (radio y ángulo). Este diseño permite una aceptable ortogonalidad entre las variables externas independientes que definen un espacio bidimensional, permitiendo un buen llenado del mismo mediante la distribución de 33 puntos, lo más espaciadamente posible sobre la superficie de la torta. Este tipo de diseño experimental, de uso no habitual es de fácil generación, es flexible para analizar efectos principales e interacciones y tiene capacidad de manejar varias variables en forma adecuada. Permite además superponer un nuevo diseño de manera que ambos cumplan con las propiedades, evitando situaciones de colapso o repetición de coordenadas codificadas en las variables independientes. En todos los casos, la muestra se toma con un sacabocado de vidrio de 6 milímetros de diámetro. La altura de la torta se mide con un calibre sobre el hueco generado respetando la posición de los 33 puntos indicados por la metodología. La humedad del sólido extraído se determina con una balanza de humedad. En los 6 casos de análisis sobre cada una de las tres tortas se realizó el modelo estadístico de la respuesta humedad y altura de torta. Se indican los efectos obtenidos de los modelos y el porcentaje de rechazo estadístico que se obtiene de la comparación cuadrática de los efectos respeto a la suma de cuadrados medio corregidos; test F. Se observó que los modelos estadísticos no producen un coeficiente de correlación lineal aceptable; sólo tiene respaldo estadístico el término independiente, el cual puede considerarse cercano al valor promedio de la humedad y la altura. Los resultados mostraron la imposibilidad de establecer un patrón en la distribución tanto para la altura como para la humedad, demostrando aleatoriedad en los valores mensurados para ambos parámetros. Esto respalda la opción de tomar pocos puntos de muestreo para la caracterización de la torta.Fil: Arnaudo, Facundo, Celeda, Ana María, Correa, Agustín F. INTEMIN-SEGEMAR .ArgentinaFil: de Celis, Jorge Pablo. Facultad de Ingeniería. UBA (Laboratorio de Química de Sistemas Heterogénos (LaQuíSiHe). Dto. de Química). Argentina y Facultad Regional Avellaneda. UTN ( Laboratorio de Investigación y Desarrollo en Ingeniería Química, (LIDIQ). Dto. Ingeniería Química)Peer Reviewe

Low back pain around retirement age and physical occupational exposure during working life

<p>Abstract</p> <p>Background</p> <p>Physical occupational exposure is a risk factor for low back pain in workers but the long term effects of exposure remain unclear. As several countries consider increasing the retirement age, further information on this topic is relevant. This study aimed to describe the prevalence of low back pain among middle aged and aging individuals in the general French population according to physical occupational exposure and retirement status.</p> <p>Methods</p> <p>The study population originated from the French national survey 'Enquête décennale santé 2002'. Low back pain for more than 30 days within the previous twelve months (LBP) was assessed using a French version of the Nordic questionnaire. Occupational exposure was self assessed. Subjects were classified as "exposed" if they were currently or had previously been exposed to handling of heavy loads and/or to tiring postures. The weighted prevalence of LBP was computed separately for men and women, for active (aged 45-59) and retiree (aged 55-74), according to 5-year age group and past/present occupational exposure.</p> <p>Results</p> <p>For active men, the prevalence of LBP was significantly higher in those currently or previously exposed (n = 1051) compared with those never exposed (n = 1183), respectively over 20% versus less than 11%. Among retired men, the prevalence of LBP tended towards equivalence with increasing age among those previously exposed (n = 748) and those unexposed (n = 599).</p> <p>Patterns were quite similar for women with a higher prevalence in exposed active women (n = 741) compared to unexposed (n = 1260): around 25% versus 15%. Similarly, differences between previously exposed (n = 430) and unexposed (n = 489) retired women tended to reduce with age.</p> <p>Conclusion</p> <p>The prevalence of LBP in active workers was associated with occupational exposure. The link with past exposure among retirees decreased with age. These results should be considered for policies dealing with prevention at the workplace and retirement.</p

Polycomb-mediated silencing in neuroendocrine prostate cancer

BACKGROUND: Neuroendocrine prostate cancer (NEPC) is a highly aggressive subtype of prostate cancer (PCa) for which the median survival remains less than a year. Current treatments are only palliative in nature, and the lack of suitable pre-clinical models has hampered previous efforts to develop novel therapeutic strategies. Addressing this need, we have recently established the first in vivo model of complete neuroendocrine transdifferentiation using patient-derived xenografts. Few genetic differences were observed between parental PCa and relapsed NEPC, suggesting that NEPC likely results from alterations that are epigenetic in nature. Thus, we sought to identify targetable epigenetic regulators whose expression was elevated in NEPC using genome-wide profiling of patient-derived xenografts and clinical samples. RESULTS: Our data indicate that multiple members of the polycomb group (PcG) family of transcriptional repressors were selectively upregulated in NEPC. Notably, CBX2 and EZH2 were consistently the most highly overexpressed epigenetic regulators across multiple datasets from clinical and xenograft tumor tissues. Given the striking upregulation of PcG genes and other transcriptional repressors, we derived a 185-gene list termed 'neuroendocrine-associated repression signature' (NEARS) by overlapping transcripts downregulated across multiple in vivo NEPC models. In line with the striking upregulation of PcG family members, NEARS was preferentially enriched with PcG target genes, suggesting a driving role for PcG silencing in NEPC. Importantly, NEARS was significantly associated with high-grade tumors, metastatic progression, and poor outcome in multiple clinical datasets, consistent with extensive literature linking PcG genes and aggressive disease progression. CONCLUSIONS: We have explored the epigenetic landscape of NEPC and provided evidence of increased PcG-mediated silencing associated with aberrant transcriptional regulation of key differentiation genes. Our results position CBX2 and EZH2 as potential therapeutic targets in NEPC, providing opportunities to explore novel strategies aimed at reversing epigenetic alterations driving this lethal disease

Structure and chromosomal location of the bovine gene for the heart muscle isoform of cytochrome c oxidase subunit VIII

We have isolated the bovine COX8H gene for the heart/muscle isoform of cytochrome c oxidase (COX) subunit VIII from a library of bovine genomic DNA cloned into lambda EMBL3. Primer extension assays on bovine heart mRNA mapped the 5′ ends of COX8H transcripts to a CA dinucleotide 62-bp upstream from the ATG codon. The gene thus spans 1565-bp and comprises two exons and one large intron of 1227 bp. Exon 1 encodes the 5′ untranslated region, a 24-amino acid presequence, and the first 13 amino acids of the mature COX VIII-H protein. Exon 2 encodes the remainder of the cDNA: amino acids 14 to 46 plus the 66-bp 3′ untranslated region. The exon-intron boundaries matched the consensus splice junction sequences. Two protein polymorphisms were seen: an Ala/Val polymorphism at position-6 in the presequence and the previously noted Lys/Arg polymorphism at residue 7 of the mature protein. A Taq I polymorphism occurs in the intron. The COX8H gene was mapped by bovine x rodent somatic cell hybrid mapping panels to bovine (BTA) Chromosome (Chr) 25 with 100% concordancy. BTA25 is conserved relative to the long arm of human (HSA) Chr 11, which contains COX8, the gene for the single human COX VIII subunit that is homologous to the liver isoform.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/47018/1/335_2004_Article_BF00303255.pd

Essays on real Exchange rate and competitiveness

In the planning of a country's economic policy, exchange rate policy has a major role, especially in less developed countries where industrial policies and foreign trade are mainly based on the exchange rate competitiveness. Therefore, it is not surprising that the exchange rate policy is used by governments and policy makers to assess the country's competitive position in the world trade. In practice, the real exchange rate (RER) is associated with the evaluation of the external position of countries through the price elasticity analysis between exports and imports. However, the assessment of countries competitive position on the basis of price elasticity is a simplified overview for understanding reality. Despite the research efforts made to cast light on the field of concern, a causal relationship between the behavior of the RER and highest competitiveness indicators remain unclear. In fact, this relationship disregards the effects of non-price competitiveness, such as competitive advantages based on the value added like high technologies applied to new products developments and new processes designs. To round up, some authors and policy makers support the assumption that the overvaluation of a currency deteriorates the competitive position of a country and that competitive devaluations facilitate growth through its positive impact on the share of the tradable goods in the economy, especially in the industry. Nevertheless, there is vast empirical evidence supporting that an appreciation of the RER will not always result in a loss of competitiveness and, conversely, RER depreciation will not always imply a higher competitiveness performance. Thus, competitiveness policies strongly based on the RER evolution through time can lead to misleading conclusions. This thesis is focused on the effects of the real exchange rate as an instrument of macroeconomic policy aimed at achieving higher indicators of competitiveness in the business sector. Theoretical and empirical evidence is offered to business decision-makers as useful information

Essays on real Exchange rate and competitiveness

In the planning of a country's economic policy, exchange rate policy has a major role, especially in less developed countries where industrial policies and foreign trade are mainly based on the exchange rate competitiveness. Therefore, it is not surprising that the exchange rate policy is used by governments and policy makers to assess the country's competitive position in the world trade. In practice, the real exchange rate (RER) is associated with the evaluation of the external position of countries through the price elasticity analysis between exports and imports. However, the assessment of countries competitive position on the basis of price elasticity is a simplified overview for understanding reality. Despite the research efforts made to cast light on the field of concern, a causal relationship between the behavior of the RER and highest competitiveness indicators remain unclear. In fact, this relationship disregards the effects of non-price competitiveness, such as competitive advantages based on the value added like high technologies applied to new products developments and new processes designs. To round up, some authors and policy makers support the assumption that the overvaluation of a currency deteriorates the competitive position of a country and that competitive devaluations facilitate growth through its positive impact on the share of the tradable goods in the economy, especially in the industry. Nevertheless, there is vast empirical evidence supporting that an appreciation of the RER will not always result in a loss of competitiveness and, conversely, RER depreciation will not always imply a higher competitiveness performance. Thus, competitiveness policies strongly based on the RER evolution through time can lead to misleading conclusions. This thesis is focused on the effects of the real exchange rate as an instrument of macroeconomic policy aimed at achieving higher indicators of competitiveness in the business sector. Theoretical and empirical evidence is offered to business decision-makers as useful information