1,273 research outputs found

    A Detailed Hydro-Economic Model for Assessing the Effects of Surface Water and Groundwater Policies: A Demonstration Model from Brazil

    Get PDF
    Policymakers, managers of water use associations, and many others in developing countries are considering policy actions that will directly or indirectly change the costs and availability of groundwater and surface water for agricultural users. While in many cases such actions may bring about welcomed increases in water use efficiency, little is known about the likely effects of changes in irrigation costs or water access on farmer behavior, or on farmer incomes in the short or long runs, and virtually nothing is known about the detailed immediate or knock-on effects on water resources that such policy actions might cause. This paper reports the preliminary results of research aiming to fill these large scientific gaps by developing a detailed hydrologic model and a detailed economic model of agriculture in the context of the Buriti Vermelho (BV) sub-catchment area of the São Francisco River Basin in Brazil. A spatially explicit, farm-level, positive mathematical programming model capable of accommodating a broad array of farm sizes and farm/farmer characteristics is being developed to predict the effects of alternative water policies and neighbors water use patterns on agricultural production. Special attention is given to precisely defining and estimating the distinct variable costs (including labor and electrical energy costs) and capital costs of surface water and groundwater, which are considered perfect substitutes for irrigation. Shadow values for non-marketed inputs (land, family labor, and water) are estimated in the first step of the modeling process. A high-resolution, spatially distributed hydrologic model (MOD-HMS) is being developed to simulate three-dimensional, variably-saturated subsurface flow and solute transport. Subsurface flow is simulated using the three-dimensional Richards equation while accounting for a) application of water at the surface, b) precipitation, c) soil evaporation and crop transpiration, and d) agricultural pumping. Demonstration versions of both models are presented and tested: the economic model assesses the effects of increasing water scarcity on cultivated area, crop mix, input mix and farm profits; the hydrologic model uses two irrigation water use scenarios to demonstrate the effects of each on surface water flows and storage, and on groundwater storage and well depth. The models are not currently linked, but a detailed plan to do so is presented and discussed. The paper concludes by discussing next steps in research and policy simulations.Resource /Energy Economics and Policy,

    Evolutionary Dynamics of Multigene Families in Triportheus (Characiformes, Triportheidae): A Transposon Mediated Mechanism?

    Get PDF
    Triportheus (Characiformes, Triportheidae) is a freshwater fish genus with 18 valid species. These fishes are widely distributed in the major river drainages of South America, having commercial importance in the fishing market, mainly in the Amazon basin. This genus has diverged recently in a complex process of speciation carried out in different river basins. The use of repetitive sequences is suitable to trace the genomic reorganizations occured along the speciation process. In this work, the 5S rDNA multigene family has been characterized at molecular and phylogenetic level. The results showed that other multigene family has been found within the non-transcribed spacer (NTS): the U1 snRNA gene. Double-FISH with 5S and U1 probes were also performed, confirming the close linkage between these two multigene families. Moreover, evidences of different transposable elements (TE) were detected within the spacer, thus suggesting a transposon-mediated mechanism of 5S-U1 evolutionary pathway in this genus. Phylogenetic analysis demonstrated a species-specific grouping, except for Triportheus pantanensis, Triportheus aff. rotundatus and Triportheus trifurcatus. The evolutionary model of the 5S rDNA in Triportheus species has been discussed. In addition, the results suggest new clues for the speciation and evolutionary trend in these species, which could be suitable to use in other Characiformes species

    Los Colorados (Provincia de La Rioja). Un caso de planificacion interpretativa.

    Get PDF
    El uso público de los recursos culturales puede constituir una alternativa económica y a su vez un incentivo para amortiguar la emigración en una región. No obstante, debe darse de una forma racional y sostenible a través de planes de manejo consensuados con la comunidad. El objetivo de este trabajo es la aplicación de conceptos de interpretación y conservación de patrimonio cultural a un caso específico: Los Colorados (La Rioja), como base para el desarrollo del turismo cultural sostenible. Uno de los principales objetivos de este plan es elaborar, para locales y visitantes, un breve acercamiento al pasado a través de las representaciones rupestres. En una segunda etapa, la intención del proyecto es integrar los sitios arqueológicos con otros lugares de interés histórico, para ofrecer al visitante una oferta más rica.publishedVersio

    Single-parameter spin-pumping in driven metallic rings with spin-orbit coupling

    Get PDF
    We consider the generation of a pure spin-current at zero bias voltage with a single time-dependent potential. To such end we study a device made of a mesoscopic ring connected to electrodes and clarify the interplay between a magnetic flux, spin-orbit coupling, and non-adiabatic driving in the production of a spin and electrical current. By using Floquet theory, we show that the generated spin to charge current ratio can be controlled by tuning the spin-orbit coupling.publishedVersionFil: Ramos Andrade, Juan Pablo. Universidad Católica del Norte. Departamento de Física; Chile.Fil: Foa Torres, Luis Eduardo Francisco. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física; Argentina.Fil: Foa Torres, Luis Eduardo Francisco. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Física Enrique Gaviola; Argentina.Fil: Orellana, P. A. Universidad Técnica Federico Santa María. Departamento de Física; Chile.Fil: Apel, Víctor Marcelo. Universidad Católica del Norte. Departamento de Física; Chile.Física de los Materiales Condensado

    A orillas del Pirgua. Representaciones rupestres en el sitio Río Pirgua 1 (Guachipas, Salta)

    Get PDF
    The department of Guachipas, Salta (Northwestern Argentina) is characterized by a concentration of archaeological sites, some of them standout because of their rock art. In this article, the Río Pirgua 1 site is described, with its rock art being compared with that from other sites in the Las Juntas micro-region. The analyzed set consisted of 96 painted motifs that included shield-shape motifs (characteristic of this area), human figures and camelids in different poses. These representations were the product of three phases of conception. The most recent coinciding with the Inca presence in the region (A.D. 1450-1535), another phase dating to the Regional Developments Period (A.D. 900-1450), and an earlier one corresponding to the first millennium of the Christian era (A.D. 0-900). Here we discuss these temporal adscriptions.El departamento de Guachipas, Salta (Noroeste Argentino) se caracteriza por la concentración de sitios arqueológicos, algunos de ellos se destacan por sus representaciones rupestres. En esta presentación se describe el sitio Río Pirgua 1 y se comparan sus representaciones con las de otros sitios de la microrregión Las Juntas. El conjunto analizado se compone de 96 motivos pintados que incluyen escutiformes (característicos del área de estudio), figuras humanas y camélidos en diferentes actitudes. Los mismos serían producto de tres momentos de ejecución. El más reciente posiblemente coincidente con la presencia inca en la región (1450-1535 d.C.), otro momento atribuido al período Desarrollos Regionales (900-1450 d.C.) y uno más temprano correspondiente al primer milenio de la era cristiana (0-900 d.C.). Se discuten las razones de esta adscripción

    Incidence of Chlamydia trachomatis and other potential pathogens in neonatal conjunctivitis.

    Get PDF
    Abstract Objective: Ocular infection in neonatology is a permanent and important health problem. To improve primary attention, prevention, and control, the study of the potential bacterial etiology of all consecutive cases of conjunctivitis was incorporated as a regular procedure in primary care from July 1995 to December 1998. Materials and Methods: Prof. A. Posadas Hospital (Great Buenos Aires) has an average of 4294 births per year. This report analyzes the results obtained in 332 infants (age range, 0–30 d) with conjunctivitis. Clinical conjunctivitis was diagnosed in inpatients and outpatients by the same specialized staff. Isolation and characterization of bacteria were done by conventional microbiologic methods, including specific search for Neisseria gonorrhoeae and Chlamydia trachomatis . Chlamydia trachomatis was studied by antigen immunodetection and polymerase chain reaction, and genotyped by restriction fragment length polymorphism. Results: Conjunctivitis had an incidence (cases per 1000 live births) of 39.6 in 1995, 25.3 in 1996, 15.4 in 1997, and 15.2 in 1998. Microbial growth was detected in 167 (50.3%) of 332 cases. Ocular C. trachomatis infection was detected in 26 cases (7.83%). Five of seven isolates in tissue cultures belonged to type E and two to type G. Bacteria from respiratory ecology were the main isolates: Haemophilus influenzae (16.9%), Streptococcus pneumoniae (12.3%), and Staphylococcus aureus (8.7%). Haemophilus influenzae isolates were not serotyped and 17.2% of them were β-lactamase producers. In 15 cases both H. influenzae and S. pneumoniae were isolated together. Of S. pneumoniae , 4,9% were oxacillin resistant. Conclusions: There has been a decline in the total number of cases of neonatal conjunctivitis, but the disease is still an important health problem. Chlamydia trachomatis also shows a decreasing profile with an incidence of (cases per 1000 live births) 4.39 in 1995, 1.85 in 1996, 1.01 in 1997, and 0.78 in 1998, and a tendency to show more incidence in spring-summer and significant accumulation of cases in babies between 7 and 9 days of age. Haemophilus influenzae alone (12.3%) or associated with S. pneumoniae (4.5%) appears as a prevalent potential bacterial pathogen. A significant accumulation of H. influenzae and S. pneumoniae cases occurs in winter. In 47.6% of cases, there was no bacterial growth. No significant seasonal differences in percentage of negative cultures or among the three-day age groups were detected. Neisseria gonorrhoeae was not found associated with ophthalmia neonatorum in this series

    Mapping Salmonella typhimurium pathways using ¹³C metabolic flux analysis

    Get PDF
    In the last years, Salmonella has been extensively studied not only due to its importance as a pathogen, but also as a host to produce pharmaceutical compounds. However, the full exploitation of Salmonella as a platform for bioproduct delivery has been hampered by the lack of information about its metabolism. Genome-scale metabolic models can be valuable tools to delineate metabolic engineering strategies as long as they closely represent the actual metabolism of the target organism. In the present study, a 13C-MFA approach was applied to map the fluxes at the central carbon pathways of S. typhimurium LT2 growing at glucose-limited chemostat cultures. The experiments were carried out in a 2L bioreactor, using defined medium enriched with 20% 13C-labeled glucose. Metabolic flux distributions in central carbon pathways of S. typhimurium LT2 were estimated using OpenFLUX2 based on the labeling pattern of biomass protein hydrolysates together with biomass composition. The results suggested that pentose phosphate is used to catabolize glucose, with minor fluxes through glycolysis. In silico simulations, using Optflux and pFBA as simulation method, allowed to study the performance of the genome-scale metabolic model. In general, the accuracy of in silico simulations was improved by the superimposition of estimated intracellular fluxes to the existing genome-scale metabolic model, showing a better fitting to the experimental extracellular fluxes, whereas the intracellular fluxes of pentose phosphate and anaplerotic reactions were poorly described.Coordenação de Aperfeiçoamento de Pessoal de Nível Superior, Brazil (CAPES) – Finance code 001. The authors also acknowledge the support of CNPq (Conselho Nacional de Desenvolvimento Científico e Tecnológico, Brazil); International cooperation project CAPES-FCT (Coordenacão de Aperfeiçoamento de Pessoal de Nível Superior/Brazil - Fundação para a Ciência e Tecnologia/Portugal - Process 315/11); CAPES, Brazil (Atração de Jovens Talentos - Process 064922/2014-01); Fundação para a Ciência e Tecnologia, Portugal (strategic funding of UID/BIO/04469 unit) and COMPETE 2020, Portugal (POCI-01-0145-FEDER-006684), in addition to the BioTecNorte operation (NORTE-01-0145-FEDER-000004) funded by European Regional Development Fund under the scope of Norte2020 - Programa Operacional Regional do Norteinfo:eu-repo/semantics/publishedVersio

    The pangenome of the Anticarsia gemmatalis multiple nucleopolyhedrovirus (AgMNPV)

    Get PDF
    The alphabaculovirusAnticarsia gemmatalismultiple nucleopolyhedrovirus (AgMNPV) is the world’s most successful viral bioinsecticide. Through the 1980s and 1990s, this virus was extensively used for biological control of populations ofAnticarsia gemmatalis(Velvetbean caterpillar) in soybean crops. During this period, genetic studies identified several variable loci in the AgMNPV; however, most of them were not characterized at the sequence level. In this study we report a full genome comparison among 17 wild-type isolates of AgMNPV. We found the pangenome of this virus to contain at least 167 hypothetical genes, 151 of which are shared by all genomes. The genebro-athat might be involved in host specificity and carrying transporter is absent in some genomes, and new hypothetical genes were observed. Among these genes there is a uniquernf12-likegene, probably implicated in ubiquitination. Events of gene fission and fusion are common, as four genes have been observed as single or split open reading frames. Gains and losses of genomic fragments (from 20 to 900 bp) are observed within tandem repeats, such as in eight direct repeats and four homologous regions. Most AgMNPV genes present low nucleotide diversity, and variable genes are mainly located in a locus known to evolve through homologous recombination. The evolution of AgMNPV is mainly driven by small indels, substitutions, gain and loss of nucleotide stretches or entire coding sequences. These variations may cause relevant phenotypic alterations, which probably affect the infectivity of AgMNPV. This work provides novel information on genomic evolution of the AgMNPV in particular and of baculoviruses in general
    corecore