2,302 research outputs found

    Input cost, capacity utilization and substitution in the short run

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    This article studies the behavior of input cost shares in an environment where labor is costly to adjust, materials can be adjusted at no cost and capital is fixed. A model relating cost shares with relative prices and adjustment costs is proposed, allowing joint estimation of the elasticity of substitution and the adjustment cost function, which is an unknown function of the utilization capacity. Based on a panel of more than 700 manufacturing firms, we find evidence of strong input share variations according to the degree of capacity utilization. The estimated shapes of adjustment costs curves of labor are in agreement with our theoretical model, and we obtain sensible elasticities of substitution estimates. Based on such estimates, we find evidence of a negative (positive) bias in downturns (recoveries) in conventional productivity growth measures

    SpectroscopicTechniques and DFT Calculations to Understand Charge Transport Mechinisms in OFETs

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    The organic electronics research field has advanced tremendously in the last decades, but there is still an incomplete understanding of the main mechanisms governing charge injection and transport in such devices. The performance of organic semiconductors is governed not only by their molecular structures but also by their intermolecular assembly in the solid state. Here we use a combination of Raman spectroscopy and charge modulation spectroscopy (CMS) to gather information on molecular and supramolecular levels, of organic semiconductors [1,2] (Figure 1) [3]. This last one is an optical-spectroscopy technique conducted on a real OFETs, that allows us to study in situ the charge carriers present at the semiconductor-dielectric interface, where the largest contribution to charge transport occurs. [3] In this communication we will present the study of the bithiophene imide (BTIn) molecules which exhibit encouraging electron mobilities in OFETs [1,2], by using the spectroscopic techniques presented above, supported by DFT quantum chemical calculations in order to shed light on the mechanism of charge transport in OFETs.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

    Malezas en las forestaciones con salicáceas del Delta del Paraná: efectos netos de las interacciones y respuesta del cultivo a distintos tratamientos de control

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    En el Delta del Paraná los sitios destinados a la forestación con Salicáceas se caracterizan por la presencia de comunidades vegetales de elevada diversidad, compuestas por especies nativas y exóticas que por su densidad e historia de vida muchas veces se comportan como malezas. En este trabajo se determinaron los efectos netos de las interacciones entre distintos clones de álamo (Populus spp.) y sauce (Salix spp.) con las comunidades vegetales de albardones y esteros, y se evaluaron las respuestas del cultivo forestal ante el control mecánico tradicional y diferentes sistemas químico-mecánicos de control de malezas. Se realizaron tres ensayos en campo, en establecimientos forestales ubicados en el Predelta y el bajo Delta del Paraná; se utilizaron los clones P. deltoides ‘Mississippi Slim’ (“Stoneville 67”), P.deltoides ‘A 208/68’ (ensayos en albardones en Islas de Ibicuy, Entre Ríos y Río Carabelas Grande, Buenos Aires), y Salix babylonica var. sacramenta (“sauce americano”; ensayo en estero, Ibicuy). Los tratamientos se realizaron durante los dos primeros años post-plantación y fueron: testigo sin control de malezas (T-), testigo con control completo de malezas, control mecánico con rolo en entrefilas y macheteadas o desmalezado con motoguadaña en las bandas de plantación, y controles químico-mecánicos con rolo en entrefilas y aplicación de herbicidas en las bandas. Las coberturas de malezas y las especies dominantes fueron diferentes entre los sitios de estero, albardón “fuera de dique” (Ibicuy) y albardón “dentro de dique” (Carabelas), pero en todos los casos predominaron los efectos de interferencia de las malezas hacia el cultivo por sobre los efectos de facilitación. Así, en los clones de álamo las malezas produjeron pérdidas de crecimiento en altura del 43 al 47% al segundo año y en el albardón de Islas de Ibicuy una merma en la supervivencia de estacas del 84%; las pérdidas de crecimiento en el albardón de Río Carabelas Grande continuaron siendo significativas cumplido el quinto año de edad, con mermas del 20% en altura total y 33% en DAP. El “sauce americano” en tanto, tuvo pérdidas al segundo año del 34% en altura y del 85% en el índice de volumen, sin que las malezas afectaran la supervivencia. El control mecánico tuvo bajas eficiencias, ya que las respuestas logradas en el cultivo no tuvieron mejoras significativas respecto de T-. Los sistemas químico-mecánicos resultaron en general más efectivos que el control mecánico, aunque con deficiencias para el control de malezas arbóreas, arbustivas y enredaderas.Facultad de Ciencias Agrarias y Forestale

    Neck circumference and clustered cardiovascular risk factors in children and adolescents: Cross-sectional study

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    Objective Early detection of cardiovascular disease (CVD) risk factors, such as obesity, is crucial to prevent adverse long-term effects on individuals'' health. Therefore, the aims were: (1) to explore the robustness of neck circumference (NC) as a predictor of CVD and examine its association with numerous anthropometric and body composition indices and (2) to release sex and age-specific NC cut-off values to classify youths as overweight/obese. Design Cross-sectional study. Setting 23 primary schools and 17 secondary schools from Spain. Participants 2198 students (1060 girls), grades 1-4 and 7-10. Measures Pubertal development, anthropometric and body composition indices, systolic and diastolic blood pressure (SBP and DBP, respectively), cardiorespiratory fitness, blood sampling triglycerides (TG), total cholesterol (TC), high-density lipoprotein cholesterol (HDL-c), low-density lipoprotein cholesterol (LDL-c), glucose and inflammatory markers. Homoeostasis model assessment (HOMA-IR) and cluster of CVD risk factors were calculated. Results NC was positively correlated with all anthropometric and body composition indices. NC was negatively associated with maximum oxygen consumption (R 2 =0.231, p<0.001 for boys; R 2 =0.018, p<0.001 for girls) and positively associated with SBP, DBP, TC/HDL-c, TG, HOMA, complement factors C-3 and C-4, leptin, adiponectin and clustered CVD risk factor in both sexes (R 2 from 0.035 to 0.353, p<0.01 for boys; R 2 from 0.024 to 0.215, p<0.001 for girls). Moreover, NC was positively associated with serum C reactive protein, LDL-c and visfatin only in boys (R 2 from 0.013 to 0.107, p<0.05). Conclusion NC is a simple, low-cost and practical screening tool of excess of upper body obesity and CVD risk factors in children and adolescents. Paediatricians can easily use it as a screening tool for overweight/obesity in children and adolescents. For this purpose, sex and age-specific thresholds to classify children and adolescents as normal weight or overweight/obese are provided

    Determinants of longitudinal changes in cardiometabolic risk in adolescents with overweight/obesity: the EVASYON study

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    We investigated which determinants (socioeconomic, early life factors, body composition changes, fitness changes and/or physical activity changes) best predicted longitudinal outcomes in cardiometabolic risk profile (Z-score change) in adolescents with OW/OB who underwent a 13-month multidisciplinary lifestyle intervention. A total of 165 adolescents (13-16 y; 46% boys) from the EVASYON study were included. Socioeconomic variables and early life factors were obtained from the medical records. Body composition was assessed using anthropometry. Fitness and physical activity were measured with field-based tests and questionnaires. Cardiometabolic risk factors (fasting glucose, HDL cholesterol, triglycerides, blood pressure and waist circumference) were derived from standard methods in the hospital. Body weight changes, sex and mother''s education were selected in the stepwise process as the most important determinants of changes in cardiometabolic risk profile (R2 = 0.26, p = 0.002; R2 = 0.14, p = 0.013; and R2 = 0.14, p = 0.017, respectively). Both boys and girls showed a lower cardiometabolic risk score with the reduction in body weight (r = 0.535, p = 0.009 and r = 0.506, p = 0.005, respectively). There was no interaction between sex and body weight change (p = 0.614). In conclusion, the simple measure of changes in body weight should be considered to track changes in cardiometabolic risk profile in adolescents with OW/OB

    Materials design for ambipolar devices: tuning orbital energetics in oligothiophene-naphthalimides semiconductors

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    Ambipolar organic field-effect transistors (OFETs), which can efficiently transport both holes and electrons, using a single type of electrode, are currently of great interest due to their possible applications in complementary metal oxide semiconductor (CMOS)-like circuits, sensors, and in light-emitting transistors. Several theoretical and experimental studies have argued that most organic semiconductors should be able to transport both types of carrier, although typically unipolar behavior is observed. One factor that can compromise ambipolar transport in organic semiconductors is poor solid state overlap between the HOMO (p-type) or LUMO (n-type) orbitals of neighboring molecules in the semiconductor thin film. In the search of low-bandgap ambipolar materials, where the absence of skeletal distortions allows closer intermolecular π-π stacking and enhanced intramolecular π-conjugation, a new family of oligothiophene-naphthalimide assemblies have been synthesized and characterized, in which both donor and acceptor moieties are directly conjugated through rigid linkers. In previous works we found that oligothiophene-napthalimide assemblies connected through amidine linkers (NDI derivates) exhibit skeletal distortions (50-60º) arising from steric hindrance between the carbonyl group of the arylene core and the sulphur atom of the neighbored thiophene ring (see Figure 1). In the present work we report novel oligo- and polythiophene–naphthalimide analogues NAI-3T, NAI-5T and poly-NAI-8C-3T, in which the connections of the amidine linkage have been inverted in order to prevent steric interactions. Thus, the nitrogen atoms are directly connected to the naphthalene moiety in NAI derivatives while they were attached directly to the thiophene moiety in the previously investigated NDI-3T and NDI-5T. In Figure 1 is depicted the calculated molecular structure of NAI-3T together with that of NDI-3T showing how the steric interactions are not present in the novel NAI derivative. The planar skeletons in these new family induce higher degree of crystallinity and the carrier charge transport can be switched from n-type to ambipolar behaviour. The highest FET performance is achieved for vapor-deposited films of NAI-3T with mobilities of 1.95x10-4cm2V-1s-1 and 2.00x10-4cm2V-1s-1 for electrons and holes, respectively. Finally, these planar semiconductors are compared with their NDI derivates analogues, which exhibit only n-type mobility, in order to understand the origin of the ambipolarity in this new series of molecular semiconductors.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

    BIORREMEDIACIÓN: ACTUALIDAD DE CONCEPTOS Y APLICACIONES

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    Vivimos una época que experimenta un crecimiento acelerado de la población y una fuerte industrialización. La humanidad, en el afán de satisfacer sus múltiples necesidades, se ha supeditado tanto a tecnologías que dañan el medio ambiente como a la dependencia de compuestos xenobióticos. En consecuencia, serios problemas de contaminación que amenazan tanto la salud de los seres vivos como del ambiente se han suscitado. Como respuesta, la biotecnología ambiental a través de la biorremediación como una de sus aplicaciones, desempeña un rol clave en la remoción de contaminantes. Diferentes sistemas biológicos de remediación, que incluyen el uso de plantas, algas, bacterias y hongos, se han empleado con éxito para tratar ambientes contaminados de metales pesados, hidrocarburos, compuestos xenobióticos, y elementos radioactivos. Aunque la biorremediación no es una tecnología nueva, esta ha ido evolucionando y se ha posicionado como un factor sustancial, tanto en términos de eficiencia como en aspectos económicos, para abatir la contaminación. Esta revisión analiza diferentes problemáticas de contaminación ambiental, describe las principales estrategias de biorremediación y detalla mecanismos moleculares empleados por algunos microorganismos para degradar compuestos tóxicos y recalcitrantes

    Presbyvestibulopathy, Comorbidities, and Perception of Disability: A Cross-Sectional Study

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    Objective: To assess the perception of disability in patients with presbyvestibulopathy and to determine the factors (demographic, balance test scores, and comorbidities) that determine higher levels of disability. Material and Methods: This was a cross-sectional study conducted in a tertiary university hospital. There were 103 patients who fulfilled the diagnostic criteria for presbyvestibulopathy and were included. Dizziness Handicap Inventory (DHI) score was the main variable used to quantify disability. Influence on DHI score, sex, age, time of evolution, equilibriometric parameters (posturographic scores and timed up and go test), history of falls, comorbidities (high blood pressure, diabetes, and dyslipidemia), psychotropic drug use, tobacco or alcohol use, living environment (urban or rural), and active lifestyle were analyzed. Results: Most of the DHI scores showed a moderate (46 patients, 44.7%) or severe (39 participants, 37.9%) handicap. DHI scores were higher in women (59.8 vs. 36.1, p < 0.001), patients with obesity (58.92 vs. 48.68; p = 0.019), benzodiazepine (59.9 vs. 49.1, p = 0.008) or other psychotropic drug (60.7 vs. 49.2, p = 0.017) users, and fallers (57.1 vs. 47.3, p = 0.048). There was also a significant positive correlation between DHI score, time (Rho coefficient: 0.371, p < 0.001), and steps (Rho coefficient: 0.284, p = 0.004) used in the TUG and with the short FES-I questionnaire (a shortened version of the Falls Efficacy Scale-International) score (Rho coefficient: 0.695, p < 0.001). DHI scores were lower in alcohol consumers than in non-drinkers (46.6 vs. 56, p = 0.048). No significant correlation was found between DHI scores and age, time of evolution, posturographic scores, comorbidities, environment (rural or urban), or active lifestyle. Conclusion: Most patients with presbyvestibulopathy show an important subjective perception of disability in relation to their symptoms. This perception is substantially higher in women than in men. The most influential factors are difficulties in walking, fear of falling, and obesity. Unique Identifier: NCT03034655, www.clinicaltrials.gov

    Modified Timed Up and Go Test for Tendency to Fall and Balance Assessment in Elderly Patients With Gait Instability

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    Objective: To compare the results from the modified Timed Up and Go Test (TUG) with posturographic variables, the subjective perception of disability due to gait instability, and the number of falls in a sample of the elderly population with imbalance, to confirm that the TUG Test is a useful clinical instrument to assess the tendency to fall in individuals of this age group. Materials and Methods: Cross-sectional study conducted in a tertiary university hospital, in 174 people aged 65 years or older with gait instability. Modified TUG Test was performed; time, step count and the need for support during the test were the analyzed variables. They were compared with the number of falls, Computerized Dynamic Posturography scores, and questionnaires scores (Dizziness Handicap Inventory and a shortened version of the Falls Efficacy Scale-International). Results: The average time to complete the TUG Test was 21.24 +/- 8.18 s, and the average step count was 27.36 +/- 7.93. One hundred two patients (58.6%) required no support to complete the test, whereas the other 72 (41.4%) used supports. The time taken to complete the Test was significantly related with having or not having fallen in the previous year, with the scores of the questionnaires, and with various parameters of dynamic posturography. A higher percentage of patients who took more than 15 s had fallen in the previous year than those who took up to 15 s to complete the test [P = 0.012; OR = 2.378; 95% CI (1.183, 4.780)]. No significant correlation was found between the step count and the number of falls in the previous year, with falling during the test or not, or with being a single or a frequent faller. No relation was found between the need for supports and the number of falls, with having or not having fallen in the previous year, or with being a single or frequent faller. Conclusion: The modified TUG Test is in relation with the presence or absence of falls. Time is the essential parameter for analyzing the risk of falling and the 15-s threshold is a good value to differentiate elderly patients at high risk of falling. Unique Identifier: NCT03034655, www.clinicaltrials.gov
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