Asymmetries in Business Cycles

Esta disertación busca estudiar los mecanismos de transmisión que vinculan el comportamiento de agentes y firmas con las asimetrías presentes en los ciclos económicos. Para lograr esto, se construyeron tres modelos DSGE. El en primer capítulo, el supuesto de función cuadrática simétrica de ajuste de la inversión fue removido, y el modelo canónico RBC fue reformulado suponiendo que des-invertir es más costoso que invertir una unidad de capital físico. En el segundo capítulo, la contribución más importante de esta disertación es presentada: la construcción de una función de utilidad general que anida aversión a la pérdida, aversión al riesgo y formación de hábitos, por medio de una función de transición suave. La razón para hacerlo así es el hecho de que los individuos son aversos a la pérdidad en recesiones, y son aversos al riesgo en auges. En el tercer capítulo, las asimetrías en los ciclos económicos son analizadas junto con ajuste asimétrico en precios y salarios en un contexto neokeynesiano, con el fin de encontrar una explicación teórica de la bien documentada asimetría presente en la Curva de Phillips.

Determinación de las condiciones de trabajo y salud del personal de laboratorios universitarios como estrategia de intervención de riesgos laborales

Introducción: Las condiciones de trabajo y salud de la población trabajadora han sido estudiadas en los diferentes sectores económicos, y para esto se han aplicado diversos instrumentos para la identificación de los factores de riesgo. Sin embargo, el estudio en los trabajadores de las instituciones de educación superior, aún es escaso y limitado. Este trabajo de investigación abordó las condiciones de trabajo y salud y los factores de riesgo asociados de los empleados de laboratorios y de talleres de las diferentes unidades de una Universidad privada en Bogotá D.C. Objetivo: Determinar las condiciones de trabajo y salud del personal de laboratorios y de talleres en el 2014 de las diferentes unidades de una Universidad privada en Bogotá D.C. Métodos: Se realizó un estudio de corte transversal, en una muestra de 87 trabajadores de laboratorios y de talleres. En el análisis univariado se calcularon para las variables cualitativas frecuencias y proporciones, y para las variables cuantitativas medidas de tendencia central y dispersión acorde a la distribución de los datos. Para el análisis bivariado, se realizó la comparación de las prevalencias entre los factores de riesgo locativos, físicos, químicos, biológicos, biomecánicos y psicológicos de cada unidad y las condiciones de trabajo y salud; así como su asociación con los factores sociodemográficos y laborales, por medio de la prueba de asociación Chi-Cuadrado de Pearson. El nivel de significancia establecido fue p<0.05. Resultados: Se encontró que las variables respiración de sustancias y manipulación manual de cargas se encuentran asociadas al cargo de los trabajadores de laboratorios y de talleres. También de la muestra de trabajadores la mayoría infirió no tener una exposición significativa a los riesgos locativo, físico, biológico y psicosocial; mientras que para riesgo químico y biomecánico se encontraron frecuencias de más del 60% entre los participantes. Los hallazgos de este estudio corresponden únicamente a la percepción de los trabajadores frente a sus condiciones de trabajo y salud, puesto que no se realizaron mediciones higiénicas ni exámenes médicos a los participantes. Conclusiones: En este estudio se encontró que la exposición a riesgos locativo, físico, biológico y psicosocial es baja; mientras que es alta para riesgo químico debida a la manipulación e inhalación de sustancias químicas tóxicas, y a riesgo biomecánico a causa de las posturas prolongadas y mantenidas, la manipulación manual de cargas, los movimientos repetitivos y realizar fuerzas. En relación a las condiciones de salud mental, se encontró que la población no presenta algún estado emocional o psicológico que llame la atención, lo que en consecuencia se refleja en el buen estado de salud físico.

Transversalidad en el aula de inglés : just say no : a drug abuse prevention unit.

Contiene: Proyecto, Versión española reducida y comentario de los alumnos sobre alcohol, no gracias. Anexo Memoria en C- Innov 106. El ejemplar con número de registro 134902 no tiene ni la versión española reducida ni los comentarios de los alumnos. Premios Nacionales a la Innovación Educativa del CIDE 1998

Test-retest reliability of distortion product otoacoustic emissions in high-risk registry neonates

This paper studies the test-retest reliability of distortion product otoacoustic emissions (DPOAE) in newborns in a neonatal intensive care unit.

Relating traits to diversification: A simple test

We describe a simple comparative method for determining whether rates of diversification are correlated with continuous traits in species-level phylogenies. This involves comparing traits of species with net speciation rate (number of nodes linking extant species with the root divided by the root to tip evolutionary distance), using a phylogenetically corrected correlation. We use simulations to examine the power of this test. We find that the approach has acceptable power to uncover relationships between speciation and a continuous trait and is robust to background random extinction; however, the power of the approach is reduced when the rate of trait evolution is decreased. The test has low power to relate diversification to traits when extinction rate is correlated with the trait. Clearly, there are inherent limitations in using only data on extant species to infer correlates of extinction; however, this approach is potentially a powerful tool in analyzing correlates of speciation.

Adventitious root formation in anacardium occidentale L. in response to phytohormones and removal of roots

Despite advances in tissue culture techniques, propagation by leafy, softwood cuttings is the preferred, practical system for vegetative reproduction of many tree and shrub species. Species are frequently defined as 'difficult'- or 'easy-to-root' when propagated by conventional cuttings. Speed of rooting is often linked with ease of propagation, and slow-to-root species may be 'difficult' precisely because tissues deteriorate prior to the formation of adventitious roots. Even when roots form, limited development of these may impair the establishment of a cutting. In this study we used softwood cuttings of cashew (Anacardium occidentale), a species considered as 'difficult-to-root'. We aimed to test the hypothesis that speed, and extent of early rooting, is critical in determining success with this species; and that the potential to form adventitious roots will decrease with time in the propagation environment. Using two genotypes, initial rooting rates were examined in the presence or absence of exogenous auxin. In cuttings that formed adventitious roots, either entire roots or root tips were removed, to determine if further root formation/development was feasible. To investigate if subsequent root responses were linked to phytohormone action, a number of cuttings were also treated with either exogenous auxin (indole-3-butyric acid-IBA) or cytokinin (zeatin). Despite the reputation of Anacardium as being 'difficult-to-root', we found high rooting rates in two genotypes (AC 10 and CCP 1001). Removing adventitious roots from cuttings and returning them to the propagation environment, resulted in subsequent re-rooting. Indeed, individual cuttings could develop new adventitious roots on four to five separate occasions over a 9 week period. Data showed that rooting potential increased, not decreased with time in the propagation environment and that cutting viability was unaffected. Root expression was faster (8-15 days) after the removal of previous roots compared to when the cuttings were first stuck (21 days). Exposing cuttings to IBA at the time of preparation, improved initial rooting in AC 10, but not in CCP 1001. Application of IBA once roots had formed had little effect on subsequent development, but zeatin reduced root length and promoted root number and dry matter accumulation. These results challenge our hypothesis, and indicate that rooting potential remains high in Anacardium. The precise mechanisms that regulate the number of adventitious roots expressed, remain to be determined. Nevertheless, results indicate that rooting potential can be high in 'difficult-to-root' species, and suggest that providing supportive environments is the key to expressing this potential. (c) 2006 Elsevier B.V. All rights reserved.

A refined LEED analysis of water on Ru{0001}: an experimental test of the partial dissociation model

Despite a number of earlier studies which seemed to confirm molecular adsorption of water on close-packed surfaces of late transition metals, new controversy has arisen over a recent theoretical work by Feibelman, according to which partial dissociation occurs on the Ru{0001} surface leading to a mixed (H2O + OH + H) superstructure. Here, we present a refined LEED-IV analysis of the (root3 x root3)R30degrees-D2O-Ru{0001} structure, testing explicitly this new model by Feibelman. Our results favour the model proposed earlier by Held and Menzel assuming intact water molecules with almost coplanar oxygen atoms and out-of-plane hydrogen atoms atop the slightly higher oxygen atoms. The partially dissociated model with an almost identical arrangement of oxygen atoms can, however, not unambiguously be excluded, especially when the single hydrogen atoms are not present in the surface unit cell. In contrast to the earlier LEED-IV analysis, we can, however, clearly exclude a buckled geometry of oxygen atoms.

Postprandial lipoprotein lipase, insulin and gastric inhibitory polypeptide responses to test meals of different fatty acid composition: comparison of saturated, n-6 and n-3 polyunsaturated fatty acids

OBJECTIVE: The present study was carried out to investigate effects of meals, rich in either saturated fatty acids (SFA), or n-6 or n-3 fatty acids, on postprandial plasma lipid and hormone concentrations as well as post-heparin plasma lipoprotein lipase (LPL) activity. DESIGN: The study was a randomized single-blind study comparing responses to three test meals. SETTING: The volunteers attended the Clinical Investigation Unit of the Royal Surrey County Hospital on three separate occasions in order to consume the meals. SUBJECTS: Twelve male volunteers with an average age of 22.5 +/- 1.4 years (mean +/- SD), were selected from the University of Surrey student population; one subject dropped out of the study because he found the test meal unpalatable. INTERVENTIONS: Three meals were given in the early evening and postprandial responses were followed overnight for 11h. The oils used to prepare each of the three test meals were: a mixed oil rich in saturated fatty acids (SFA) which mimicked the fatty acid composition of the current UK diet, corn oil, rich in n-6 fatty acids and a fish oil concentrate (MaxEPA) rich in n-3 fatty acids. The oil under investigation (40 g) was incorporated into the test meals which were otherwise identical [208 g carbohydrates, 35 g protein, 5.65 MJ (1350 kcal) energy]. Postprandial plasma triacylglycerol (TAG), gastric inhibitory polypeptide (GIP), and insulin responses, as well as post-heparin LPL activity (measured at 12 h postprandially only) were investigated. RESULTS: Fatty acids of the n-3 series significantly reduced plasma TAG responses compared to the mixed oil meal (P < 0.05) and increased post-heparin LPL activity 15 min after the injection of heparin (P < 0.01). A biphasic response was observed in TAG, with peak responses occurring at 1 h and between 3-7 h postprandially. GIP and insulin showed similar responses to the three test meals and no significant differences were observed. CONCLUSION: We conclude that fish oils can decrease postprandial plasma TAG levels partly through an increase in post-heparin LPL activity, which however, is not due to increased GIP or insulin concentrations.

High-throughput root phenotyping screens identify genetic loci associated with root architectural traits in Brassica napus under contrasting phosphate availabilities

Background and Aims: Phosphate (Pi) deficiency in soils is a major limiting factor for crop growth worldwide. Plant growth under low Pi conditions correlates with root architectural traits and it may therefore be possible to select these traits for crop improvement. The aim of this study was to characterize root architectural traits, and to test quantitative trait loci (QTL) associated with these traits, under low Pi (LP) and high Pi (HP) availability in Brassica napus. Methods: Root architectural traits were characterized in seedlings of a double haploid (DH) mapping population (n = 190) of B. napus 'Tapidor' x 'Ningyou 7' (TNDH) using high-throughput phenotyping methods. Primary root length (PRL), lateral root length (LRL), lateral root number (LRN), lateral root density (LRD) and biomass traits were measured 12 d post-germination in agar at LP and HP. Key Results: In general, root and biomass traits were highly correlated under LP and HP conditions. 'Ningyou 7' had greater LRL, LRN and LRD than 'Tapidor', at both LP and HP availability, but smaller PRL. A cluster of highly significant QTL for LRN, LRD and biomass traits at LP availability were identified on chromosome A03; QTL for PRL were identified on chromosomes A07 and C06. Conclusions: High-throughput phenotyping of Brassica can be used to identify root architectural traits which correlate with shoot biomass. It is feasible that these traits could be used in crop improvement strategies. The identification of QTL linked to root traits under LP and HP conditions provides further insights on the genetic basis of plant tolerance to P deficiency, and these QTL warrant further dissection.

Root distributions of Australian herbaceous perennial legumes in response to phosphorus placement

Many Australian plant species have specific root adaptations for growth in phosphorus-impoverished soils, and are often sensitive to high external P concentrations. The growth responses of native Australian legumes in agricultural soils with elevated P availability in the surface horizons are unknown. The aim of these experiments was to test the hypothesis that increased P concentration in surface soil would reduce root proliferation at depth in native legumes. The effect of P placement on root distribution was assessed for two Australian legumes, Kennedia prorepens F. Muell. and Lotus australis Andrews, and the exotic Medicago sativa L. Three treatments were established in a low-P loam soil: amendment of 0.15 g mono-calcium phosphate in either (i) the top 50 mm (120 µg P g–1) or (ii) the top 500 mm (12 µg P g–1) of soil, and an unamended control. In the unamended soil M. sativa was shallow rooted, with 58% of the root length of in the top 50 mm. K. prorepens and L. australis had a more even distribution down the pot length, with only 4 and 22% of their roots in the 0–50 mm pot section, respectively. When exposed to amendment of P in the top 50 mm, root length in the top 50 mm increased 4-fold for K. prorepens and 10-fold for M. sativa, although the pattern of root distribution did not change for M. sativa. L. australis was relatively unresponsive to P additions and had an even distribution of roots down the pot. Shoot P concentrations differed according to species but not treatment (K. prorepens 2.1 mg g–1, L. australis 2.4 mg g–1, M. sativa 3.2 mg g–1). Total shoot P content was higher for K. prorepens than for the other species in all treatments. In a second experiment, mono-ester phosphatases were analysed from 1-mm slices of soil collected directly adjacent to the rhizosphere. All species exuded phosphatases into the rhizosphere, but addition of P to soil reduced phosphatase activity only for K. prorepens. Overall, high P concentration in the surface soil altered root distribution, but did not reduce root proliferation at depth. Furthermore, the Australian herbaceous perennial legumes had root distributions that enhanced P acquisition from low-P soils.

Generic construction of monitors for floating point unit designs

This paper proposes a set of well defined steps to design functional verification monitors intended to verify Floating Point Units (FPU) described in HDL. The first step consists on defining the input and output domain coverage. Next, the corner cases are defined. Finally, an already verified reference model is used in order to test the correctness of the Device Under Verification (DUV). As a case study a monitor for an IEEE754-2008 compliant design is implemented. This monitor is built to be easily instantiated into verification frameworks such as OVM. Two different designs were verified reaching complete input coverage and successful compliant results.

Host and habitat filtering in seedling root-associated fungal communities: taxonomic and functional diversity are altered in ‘novel’ soils

Climatic and land use changes have significant consequences for the distribution of tree species, both through natural dispersal processes and following management prescriptions. Responses to these changes will be expressed most strongly in seedlings near current species range boundaries. In northern temperate forest ecosystems, where changes are already being observed, ectomycorrhizal fungi contribute significantly to successful tree establishment. We hypothesised that communities of fungal symbionts might therefore play a role in facilitating, or limiting, host seedling range expansion. To test this hypothesis, ectomycorrhizal communities of interior Douglas-fir and interior lodgepole pine seedlings were analysed in a common greenhouse environment following growth in five soils collected along an ecosystem gradient. Currently, Douglas-fir’s natural distribution encompasses three of the five soils, whereas lodgepole pine’s extends much further north. Host filtering was evident amongst the 29 fungal species encountered: 7 were shared, 9 exclusive to Douglas-fir and 13 exclusive to lodgepole pine. Seedlings of both host species formed symbioses with each soil fungal community, thus Douglas-fir did so even where those soils came from outside its current distribution. However, these latter communities displayed significant taxonomic and functional differences to those found within the host distribution, indicative of habitat filtering. In contrast, lodgepole pine fungal communities displayed high functional similarity across the soil gradient. Taxonomic and/or functional shifts in Douglas-fir fungal communities may prove ecologically significant during the predicted northward migration of this species; especially in combination with changes in climate and management operations, such as seed transfer across geographical regions for forestry purposes.

Comparison between two surgical techniques for root coverage with an acellular dermal matrix graft

Aim: The aim of this randomized, controlled, clinical study was to compare two surgical techniques with the acellular dermal matrix graft (ADMG) to evaluate which technique could provide better root coverage. Material and Methods: Fifteen patients with bilateral Miller Class I gingival recession areas were selected. In each patient, one recession area was randomly assigned to the control group, while the contra-lateral recession area was assigned to the test group. The ADMG was used in both groups. The control group was treated with a broader flap and vertical-releasing incisions, and the test group was treated with the proposed surgical technique, without releasing incisions. The clinical parameters evaluated before the surgeries and after 12 months were: gingival recession height, probing depth, relative clinical attachment level and the width and thickness of keratinized tissue. Results: There were no statistically significant differences between the groups for all parameters at baseline. After 12 months, there was a statistically significant reduction in recession height in both groups, and there was no statistically significant difference between the techniques with regard to root coverage. Conclusions: Both surgical techniques provided significant reduction in gingival recession height after 12 months, and similar results in relation to root coverage.

Matrix Metalloproteinase Expression in Teeth with Apical Periodontitis Is Differentially Modulated by the Modality of Root Canal Treatment

Introduction: The objective of this study was to investigate the expression of matrix metalloproteinases (MM Ps) in apical periodontitis and during the periapical healing phase after root canal treatment. Methods: Apical periodontitis was induced in dog teeth, and root canal treatment was performed in a single visit or by using an additional calcium hydroxide root canal dressing. One hundred eighty days after treatment the presence of inflammation was examined, and tissues were stained to detect bacteria. Bacterial status was correlated to the degree of tissue organization, and to further investigate molecules involved in this process, tissues were stained for MMP-1, MMP-2, MMP-8, and MMP-9. Data were analyzed by using one-way analysis of variance followed by Tukey test or Kruskal-Wallis followed by Dunn test. Results: Teeth with apical periodontitis that had root canal therapy performed in a single visit presented an intense inflammatory cell infiltrate. Periapical tissue was extremely disorganized, and this was correlated with the presence of bacteria. Higher MMP expression was evident, similar to teeth with untreated apical periodontitis. In contrast, teeth with apical periodontitis submitted to root canal treatment with calcium hydroxide presented a lower inflammatory cell infiltrate. This group had moderately organized connective tissue, lower prevalence of bacteria, and lower number of MMP-positive cells, similar to healthy teeth submitted to treatment. Conclusions: Teeth treated with calcium hydroxide root canal dressing exhibited a lower percentage of bacterial contamination, a lower MMP expression, and a more organized extracellular matrix, unlike those treated in a single visit. This suggests that calcium hydroxide might be beneficial in tissue repair processes. (J Endod 2010;36:231-237)

Scanning Electron Microscopic Preliminary Study of the Efficacy of SmearClear and EDTA for Smear Layer Removal after Root Canal Instrumentation in Permanent Teeth

This study aimed to evaluate the efficacy of SmearClear (SybronEndo, Orange, CA) and EDTA for smear layer removal from root canals of permanent teeth after instrumentation. Thirty extracted human permanent teeth (n = 10) were randomly assigned to the following groups: group 1 = 14.3% EDTA, group 2 = SmearClear, and group 3 = no smear layer removal procedure was undertaken (control). The specimens were submitted to scanning electron microscopy analysis. Magnifications of 200x and 750x were used to evaluate cleaning at the apical, middle, and cervical thirds according to a three-point scoring system. Data were analyzed statistically by the Mann-Whitney U test (5% significance level). Groups 1 and 2 differed significantly from group 3 (p < 0.01). However, there was no statistically significant difference (p > 0.05) between groups 1 and 2. In conclusion, SmearClear was able to remove the smear layer from the root canals of permanent teeth similarly as 14.3% EDTA, suggesting that both solutions may be indicated for such purpose. (J Endod 2008,34:1541-1544)