2,821 research outputs found

    Environmentally friendly technologies to maintain stored paddy rice quality

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    Exports of processed rice have been increasing every year, as well as legislative restrictions and consumer demand for certified chemical free rice, pressing the rice processing industry to new challenges. The objective of this work was the implementation of a Rice Quality Certification Program. The package includes the association of a rigorous sanitation program and safe environmentally friendly control measures. It was accomplished in a large paddy rice facility with 40 silos during the 2008/09 rice crop. Silo sanitation was done by washing with pressurized water the conveyor belt structure above the silo roof, around the externals walls and thorough aspiration of the aeration system. During silo filling, the lower and top portions of the rice grain were treated with a mixture of diatomaceous earth (DE) and powder deltamethrin. Artificial chilling was applied as soon as the top layer of the grain mass was leveled by insufflating cool air (6 to 8ºC) with a large cooling machine through the aeration system. The grain mass temperature stabilized at about 12-14ºC, and kept this range of temperature for about 60 d. As the temperature of the grain mass increased, mainly on the top layer, aeration was performed with natural air from the cold fronts during the winter months. After 8 months on storage the rice was free of external insects, as proved by the grain sampling just before processing. For the 2009/10 crop season, the rice quality program will be repeated on 60 silos with few adjustments.Keywords: Chilled aeration, Inert dust, Physical insect control, Rice quality maintenance

    Potential Response of Soil-Borne Fungal Pathogens Affecting Crops to a Scenario of Climate Change in Europe

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    A study was carried out on the potential response of soil-borne pathogens causing crop yield losses under a climate change scenario in Europe. A controlled chamber set of experiments was carried out to quantify pathogen response to temperature using pure colonies of three soil-borne fungi, representative of low (Fusarium nivale), medium-high (Athelia rolfsii) and high (Macrophomina phaseolina) temperature requirements. A generic model to simulate fungal growth response to temperature based on these experiments was developed and linked to a soil temperature model component, and to components to simulate soil water content accounting for crop water uptake of potential hosts. Pathogens relative growth was simulated over Europe using the IPCC A1B emission scenario as realization of the Hadley-CM3 global climate model, available from the European Commission and processed for use with biophysical models. The simulations resulting from using the time span centred on 2030 were compared to the baseline, centred on the year 2000, using a sample of 30 years of daily weather. The general trend of soil-borne pathogens response to the scenario of climate change is a relative increase in growth in colder areas of Europe, as a function of their temperature requirements. Projections of F. nivale in the future indicate a relative increase of this winter pathogen of wheat in Northern European countries. A. rolfsii and M. phaseolina, two soil-borne pathogens typical of warmer agricultural areas, could find more favourable conditions in areas of the Central Europe, but they differentiated in Southern Europe where A. rolfsii resulted affected by summer soil temperatures above optimum

    Spatial distribution of stored grain insects in a rice storage and processing facility in Brazil

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    This study describes the spatial distribution of stored product insects captured biweekly using foodbaited cage traps in a large rice storage and processing facility, in the state of Rio Grande do Sul, Brazil. Monitoring started in August 2009 and will be carried out for 1 year, the first 5 months of sampling being presented in this study. From end of August 2009 until the end of December 2009, a total of 9893 insects were captured in the 99 cage traps. The most abundant species were: Carpophilus spp. (76%), Typhaea stercorea (8.6%), Ahasverus advena (5.5%), Tribolium castaneum (2.3%), Sitophilus oryzae (2%), Sitophilus zeamais (1.5%), Ephestia spp. (1.2 %), Cryptolestes ferrugineus (1%), Rhyzopertha dominica (0.64%), Oryzaephilus surinamensis (0.6%), Anthicus floralis (0.4%), Lasioderma serricorne (0.25%). The first two species, which make up for 84.6% of the insects collected, are not considered pests in stored grain, rather are attracted by moldy material present in residues or even in the bait material. The other insects, including primary and secondary species, comprised about 15% of the total trapped. The spatial distribution of the most important species infesting rice grain and of the total insect number was analyzed using Surfer 6.04 (Golden software, Golden, CO, USA) and contour maps were constructed to target areas for sanitation. Except for trap 66, located by the rice hulk storage box, the spatial distribution we observed using the contour maps showed that the greatest number of insects was mostly captured in cages placed in the receiving area, around the dryers, as well as outside of the structure where grain residues frequently accumulate. As indicated on the maps for total number of insects, a few isolated infested spots were detected. The parboiled rice area had the least amount of insects, except for trap 61, placed outside the structure. The population of primary and the most important secondary insect species, as well as the overall number of insects, decreased after sanitation and physical control measures were applied. Our observations confirm that insect monitoring is an essential tool for targeting and evaluating the control measures adopted in the quality program of rice storage and processing facilities. Keywords: Insect monitoring; Spatial distribution; Stored grain pests; Stored ric

    Stability of a buoyant Oldroyd-B flow saturating a vertical porous layer with open boundaries

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    The performance of several engineering applications are strictly connected to the rheology of the working fluids and the Oldroyd-B model is widely employed to describe a linear viscoelastic behaviour. In the present paper, a buoyant Oldroyd-B flow in a vertical porous layer with permeable and isothermal boundaries is investigated. Seepage flow is modelled through an extended version of Darcy’s law which accounts for the Oldroyd-B rheology. The basic stationary flow is parallel to the vertical axis and describes a single-cell pattern where the cell has an infinite height. A linear stability analysis of such a basic flow is carried out to determine the onset conditions for a multicellular pattern. This analysis is performed numerically by employing the shooting method. The neutral stability curves and the values of the critical Rayleigh number are evaluated for different retardation time and relaxation time characteristics of the fluid. The study highlights the extent to which the viscoelasticity has a destabilising effect on the buoyant flow. For the limiting case of a Newtonian fluid, the known results available in the literature are recovered, namely a critical value of the Darcy–Rayleigh number equal to 197.081 and a corresponding critical wavenumber of 1.05950

    Clinical Features And Laboratory Patterns In A Cohort Of Consecutive Argentinian Patients With Von Willebrand's Disease

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    Background and Objectives. von Willebrand's disease (vWD) is a bleeding disorder with variable clinical expression. Our aim was to classify patients with vWD and to determine the phenotype in their relatives. Design and Methods. The types and subtypes, blood group frequency and its relevance, bleeding sites, response to the desmopressin (DDAVP) test, transfusion requirements and clinical features in type 1 and 2A families were determined in 1,885 patients. Results. Our findings were: type 1: 91%, type 2A: 3.1%, severe vWD: 1.3%; type 2N: 1.6%; type low intraplatelet: 2.7%; combined 1+2N: 0.3%. Blood group O prevalence was 70.5%. Bleeding and transfusion requirements were not correlated to blood groups. The most frequent symptoms were: ecchymoses-hematomas and epistaxis and, in females over 13 years, also menorrhagia. Normal levels of factor VIII:C were found in 38.4% of the patients. DDAVP was infused in 567 patients with a good response in 80.6%. About 9% of our patients needed transfusion therapy. The diagnosis of von Willebrand’s disease is more likely in subjects belonging to families with type 2A disease than in members of families with type 1 vWD in spite of these being symptomatic. Interpretation and Conclusions. These observations provide a good strategy to identify, classify and treat vWD patients without performing molecular assays.Fil: Woods, Adriana Inés. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Academia Nacional de Medicina de Buenos Aires; ArgentinaFil: Meschengieser, S. S.. Academia Nacional de Medicina de Buenos Aires; ArgentinaFil: Blanco, A. N.. Academia Nacional de Medicina de Buenos Aires; ArgentinaFil: Salviu, M. J.. Academia Nacional de Medicina de Buenos Aires; ArgentinaFil: Farias, Cristina Elena. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Academia Nacional de Medicina de Buenos Aires; ArgentinaFil: Kempfer, Ana Catalina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Academia Nacional de Medicina de Buenos Aires; ArgentinaFil: Lazzari, María Ángela. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Academia Nacional de Medicina de Buenos Aires; Argentin

    Should the General Practitioner Consider Mesotherapy (Intradermal Therapy) to Manage Localized Pain?

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    Wide variations in the types of pain and response to analgesic pharmacotherapy mean that a variety of treatment strategies are needed. One approach is mesotherapy (intradermal therapy). This consists of microinjections into the skin and is ideally suited to the management of localized pain. Advantages include increasing the duration of drug activity, reduced risk of adverse events and interactions, and possible synergy with other therapies. Mesotherapy provides general practitioners with another tool for the treatment of local pain. However, it is important to provide patients with full details of the pros and cons of this approach and obtain informed patient consent

    Intra and interspecific variation assessment in Psocoptera using near spectoscopy

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    Several species of Psocoptera are associated with and damage grains and other stored products, books, historical documents, and insect collections. Their small size and lack of expressive morphological variation make it a difficult group for species identification. The spectra of adult males and females of 10 psocid species from the genus Liposcelis were obtained by near infrared spectroscopy (NIRS) and analyzed. Each specimen was placed on a diffuse reflectance accessory of a NIR spectrometer to obtain the respective spectrum, using ten replicates for each species or sex. All spectra were analyzed by combined methods of multivariate analysis using the technique of crossed validation for the multivariate models. The analysis discriminated the species without significant overlapping among the species spectral patterns. The NIRS also revealed variation in the metabolomic profile of males and females; however, it is still possible to distinguish the species using only males or females or even from mixed sex samples. NIRS technique proved to be a powerful tool to discriminate species both at intra and interspecific levels based on dispersion spectral patterns of individual specimens. Keywords: Biological systems, Liposcelididae, stored product pests, Vibrational spectroscopy

    Thermal Convection of an Ellis Fluid Saturating a Porous Layer with Constant Heat Flux Boundary Conditions

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    The present work analyzes the thermal instability of mixed convection in a horizontal porous channel that is saturated by a shear-thinning fluid following Ellis’ rheology. The fluid layer is heated from below by a constant heat flux and cooled from above by the same heat flux. The instability of such a system is investigated by means of a small-disturbances analysis and the resulting eigenvalue problem is solved numerically by means of a shooting method. It is demonstrated that the most unstable modes on the instability threshold are those with infinite wavelength and an analytical expression for such conditions is derived from an asymptotic analysis. Results show that the non-Newtonian character of the fluid has a destabilizing role

    Unstable Convection in a Vertical Double–Layer Porous Slab

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    A convective stability analysis of the flow in a vertical fluid-saturated porous slab made of two layers with different thermophysical properties is presented. The external boundaries are isothermal with one of them impermeable while the other is open to an external fluid reservoir. This study is a development of previous investigations on the onset of thermal instability in a vertical heterogeneous porous slab where the heterogeneity may be either continuous or piecewise as determined by a multilayer structure. The aim of this paper is investigating whether a two-layer structure of the porous slab may lead to the onset of cellular convection patterns. The linear stability analysis is carried out under the assumption that one porous layer has a thermal conductivity much higher than the other layer. This assumption may be justified for the model of a heat transfer enhancement system involving a saturated metal foam. A flow model for the natural convection based on Darcy’s momentum transfer in a porous medium is adopted. The buoyancy-induced basic flow state is evaluated analytically. Small-amplitude two-dimensional perturbations of the basic state are introduced, thus leading to a linear set of governing equations for the disturbances. A normal mode analysis allows one to formulate the stability eigenvalue problem. The numerical solution of the stability eigenvalue problem provides the onset conditions for the thermal instability. Moreover, the results evidence that the permeability ratio of the two layers is a key parameter for the critical conditions of the instability
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