118,272 research outputs found
Desarrollo de modelos predictivos para la evaluación del impacto de la dinámica poblacional durante la fase de establecimiento y productividad de pasturas cultivadas en siembra directa
No full textTesis (Doctor en Ciencias Agropecuarias) -- UNC- Facultad de Ciencias Agropecuarias, 2019Fil: Zarza Fuentes, Rodrigo T. Instituto Nacional de Investigación Agropecuaria (INIA). La Estanzuela; Uruguay.Fil: Balzarini, Mónica Graciela. Universidad Nacional de Córdoba. Facultad de Ciencias Agropecuarias. Cátedra de Estadística y Biometría; Argentina.Fil: Balzarini, Mónica Graciela. Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET). Centro Científico Tecnológico (CCT Córdoba); Argentina.La intensificación y la marginalidad de las áreas incorporadas al sector lechero en la última década en Uruguay se asocian a incrementos en los riesgos de fallas durante el establecimiento. El éxito de una pastura requiere una correcta implantación y rápida cobertura del suelo; una evaluación temprana podría aportar herramientas para alcanzar estos objetivos. La densidad de plantas logradas puede ser un predictor de biomasa en sistemas pastoriles intensivos donde las leguminosas ofrecen un alimento de alta calidad y bajo costo. La alfalfa (Medicago sativa L.) tiene un crecimiento estival que combina alto potencial de crecimiento y persistencia; trébol rojo (Trifolium pratense L.) es otra alternativa perenne, aunque de persistencia limitada que, en suelos pesados, constituye una alternativa de alto potencial. Ambas especies en forma pura o en mezclas (bienales o perennes de larga duración) integran las rotaciones forrajeras en los sistemas pastoriles. Este trabajo registró conteos de plántulas de estas pasturas a las 3, 7 y 12 semanas desde la siembra en una red de ensayos en Uruguay (tres localidades y tres años en cada localidad). A través del uso de diferentes densidades de siembra se simularon diferentes niveles de logros en la implantación de pasturas puras de alfalfa y trébol rojo, así como en mezclas bienales de trébol rojo con Cichorium intybus L. o Bromus catharticus Vahl. y en mezclas perennes de larga duración donde la alfalfa se acompañó de Festuca arundinacea Schreb. o de Dactylis glomerata L. con Trifolium repens L. como leguminosa acompañante. Los recuentos de plantas se usaron como predictores de la producción acumulada anual de forraje. La relación entre productividad de forraje y densidad de plantas durante el monitoreo del establecimiento fue ajustada con un polinomio de segundo orden. La variabilidad ambiental, clasificando los ambientes en tres categorías (bueno, intermedio y pobre), se incorporó al modelo mediante un efecto aleatorio de ambiente. La densidad de plantas de alfalfa y de trébol rojo a las 3 semanas después de la siembra proporcionó una buena medida del establecimiento de la pastura y permitió la predicción de la productividad de biomasa (error <20%) tanto en las pasturas puras como en mezclas. La precisión de esta predicción varió en función de la calidad del ambiente. Las pasturas sembradas en ambientes intermedios y relativamente buenos produjeron biomasas más relacionadas con la densidad de plantas durante el establecimiento que las pasturas de ambientes más pobres. Se calcularon probabilidades de superar producciones umbrales bajo distintos escenarios de calidad de implantación de las leguminosas (puras o en mezclas) estimada por recuentos tempranos de plántulas, que constituyen una herramienta útil para la presupuestación forrajera de los sistemas lecheros bajo diferentes contextos ambientales.The intensification and marginalization of the areas incorporated to the dairy sector in the last decade in Uruguay are associated with increases in the risks of failures during the establishment. The success of a pasture requires a correct implantation and rapid coverage of soil; an early evaluation could provide tools to achieve these objectives. Plants density could be a predictor of biomass in intensive pastoral systems where legumes offer a high quality and low-cost feed. Alfalfa (Medicago sativa L.) has a summer growth that combines high potential for growth and persistence; red clover (Trifolium pratense L.) is another perennial alternative although of limited persistence, that in heavy soils, constitutes a high potential alternative. Both legumes, either in pure stands or in mixtures (biennial or long-term perennials), integrate forage rotations in pastoral systems. This study recorded seedling counts at 3, 7 and 12 weeks after sowing in a network of trials in Uruguay (three localities and three years in each locality). Using different planting densities, different levels of achievements were simulated in the implantation of pure alfalfa and red clover pastures, as well as in biennial mixtures of red clover with Cichorium intybus L. or Bromus catharticus Vahl. and in long-lasting perennial mixtures where alfalfa was accompanied by Festuca arundinacea Schreb. or Dactylis glomerata L. with Trifolium repens L. as accompanying legume. Plant counts were used as predictors of cumulative annual forage production. The relationship between forage productivity and plant density during establishment was adjusted under several scenarios. Environmental variability, classifying the environments into three categories (good, intermediate and poor), was incorporated into the model by means of a random effect. The density of alfalfa and red clover plants at 3 weeks after planting provided a good measure of pasture establishment and allowed prediction of biomass productivity (error <20%) both in pure pastures and in mixtures. The accuracy of prediction varied with the quality of the environment. Pastures planted in intermediate and relatively good environments produced biomasses more related to the plant density achieved than the pastures in poorer environments. Probabilities of surpassing threshold productions were calculated under different scenarios of legume implantation quality (pure or in mixtures) estimated by early counts of seedlings, that constitute a useful tool for forage budgeting of dairy systems under different environmental contexts.Fil: Zarza Fuentes, Rodrigo T. Instituto Nacional de Investigación Agropecuaria (INIA). La Estanzuela; Uruguay.Fil: Balzarini, Mónica Graciela. Universidad Nacional de Córdoba. Facultad de Ciencias Agropecuarias. Cátedra de Estadística y Biometría; Argentina.Fil: Balzarini, Mónica Graciela. Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET). Centro Científico Tecnológico (CCT Córdoba); Argentina
MRI in Crohn's disease : current and future clinical applications
No full textCrohn's disease is a chronic, disabling disease that, over time, can lead to irreversible bowel damage. MRI can be used to diagnose and assess the activity, severity and complications of Crohn's disease; however, the role of MRI in therapeutic monitoring of changes in disease-related intestinal damage is still to be defined. Objective, validated MRI-based scores have been developed to assess the activity of Crohn's disease; these indices are based on the extent and severity of intestinal inflammation, postoperative recurrence and perianal disease. MRI is accurate, safe, reproducible and can allow repeated evaluations of patients without radiation exposure. Evidence that MRI might be valuable in the therapeutic monitoring of patients with Crohn's disease is increasing and, in combination with endoscopy and surgical history, this imaging technique could enable clinicians to assess Crohn's-disease-related intestinal damage. MRI could, therefore, have a crucial role in a future 'damage-driven' treatment paradigm--in which imaging is used to monitor intestinal damage and medication use is targeted to prevent the accumulation of further damage. This damage-driven therapeutic approach could potentially change the course of Crohn's disease
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Itaconic acid carrier ampholytes for isoelectric focusing
No full textCommercial carrier ampholytes, obtained by coupling polyethylene polyamines to acrylic acid, exhibit a conductivity minimum in the pH range 5.5-6.5 owing to the lack of appropriate pK values of the polyamine in this pH region. By replacing acrylic with itaconic acid, it has been possible to effect substantial improvements in the pH range 5.5-6.5 as itaconic acid has a pK2 value of 5.45. Upon coupling, the pK of the gramma-carboxyl group remains virtually unaltered. With itoconic acid carrier ampholytes it has been possible to improve the conductivity in the pH range 5.5-6.5 by as much as 400% compared with conventional carrier ampholytes. It is suggected that the commercial products should be supplemented with itaconic acid carrier ampholytes in order to obtain a more uniform conductivity and buffering capacity in the pH range 3-10
Prevalence of huntington disease in Italy: A systematic review and meta-analysis
No full textWorldwide prevalence of Huntington’s disease (HD) is quite heterogenous. As Italy is characterized by significant genetic heterogeneity, with presumptive differences between Italian regions, this review was undertaken to define available data of HD prevalence in Italy, to assess geographic heterogeneity, and reconcile possible variation in HD prevalence rates with the availability of genetic testing. Methods. In total, 14 relevant studies were identified from Medline/Embase, and analysis of available Italian regional reports on rare diseases. Results. A cumulative prevalence of 3.9/100,000 inhabitants (95% Confidence Interval 3.0 - 5.0) was identified, with apparently higher rates in the last decades (4.1/100,000 vs. 3.0/100,000). The lowest rates were among the resident of the Oristano province in Sardinia, while the highest were reported in three mountainous and rather isolated areas (i.e. Molise, San Marino, Varese; all well over 10 cases/100,000 inhabitants). These differences cannot be not fully explained by varying approaches to case-ascertainment or diagnosis, and a possible “founder effect” may therefore be extensively advocated. Discussion. The prevalence of HD in retrieved Italian reports varied up to almost tenfold between different geographical regions. Even though such variation can in part be attributed to differences in case-ascertainment and/or diagnostic criteria, there is consistent evidence of significant founder effects in certain areas such as the provinces of Varese, the Republic of San Marino, and the region od Molise - all of them with estimates > 10/100,000 cases. As our estimates suggest that up to half of Italian HD cases may be still waiting, Public Health approach should improve diagnostic rates in order to guaranteeing palliative and symptomatic interventions (antidepressants, antipsychotics, anti-choreiform medications) to all individuals and their families
Air temperatures and occupational injuries in the construction industries: A report from northern Italy (2000–2013)
No full textThe aim of this study was to assess the relationship between environmental temperatures and occupational injuries (OIs) in construction workers (CWs) from a subalpine region of North-Eastern Italy. Data about OIs from 2000 to 2013, and daily weather for the specific site of the events were retrieved. Risk for daily OIs was calculate through a Poisson regression model. Estimated daily incidence for OIs was 5.7 (95%CI 5.5–5.8), or 2.8 OIs/10,000 workers/d (95%CI 2.7–2.9), with higher rates for time periods characterized by high temperatures (daily maximum ≥35°C), both in first 2 d (3.57, 95%CI 3.05–4.11) and from the third day onwards (i.e. during Heat Waves: 3.43, 95%CI 3.08–3.77). Higher risk for OIs was reported in days characterized temperatures ≥95th per-centile (OR 1.145, 95%CI 1.062–1.235), summer days (daily maximum ≥25°C, OR 1.093, 95%CI 1.042–1.146). On the contrary, no significant increased risk was found for OIs having a more severe prognosis (≥40 d or more; death). In conclusion, presented findings recommend policymakers to develop appropriate procedures and guidelines, in particular aimed to improve the compliance of younger CWs towards severe-hot daily temperatures
Air temperatures and occupational injuries in the construction industries: A report from northern Italy (2000–2013)
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