795 research outputs found
Graviton emission from a higher-dimensional black hole
We discuss the graviton absorption probability (greybody factor) and the
cross-section of a higher-dimensional Schwarzschild black hole (BH). We are
motivated by the suggestion that a great many BHs may be produced at the LHC
and bearing this fact in mind, for simplicity, we shall investigate the
intermediate energy regime for a static Schwarzschild BH. That is, for
, where is the mass of the black hole and
is the energy of the emitted gravitons in -dimensions. To find
easily tractable solutions we work in the limit , where is the
angular momentum quantum number of the graviton.Comment: 10 pages, 8 figures, references added, typos corrected. Graviton
degeneracy factor included; main results remain unchange
Operation of a perfusive catalytic membrane with nonlinear kinetics
Operation of a perfusive catalytic curved membrane is systematized into different transport-reaction regimes. The internal viscous permeation improves the catalyst performance, measured here by the effectiveness factor and by its enhancement relative to purely diffusive conditions. A theoretical analysis is presented for nonlinear kinetic expressions, which are suitable to describe the consumption of a reactant in many (bio)catalytic systems. The kinetic and transport parameters required to attain maximum enhancement are related by simple design rules, which depend on the form of the reaction rate law (namely on the order of reaction and dimensionless inhibition constant). For zero-order reactions, these optimum conditions correspond to attaining negligible concentration at a position inside the membrane, while may be interpreted in general as separating situations of severe mass transfer resistance from cases of high effectiveness. It is important to incorporate the correct form of the kinetic expression in the analysis, so that the predictions can be used in a quantitative manner. The results for the different regimes are compiled in enhancement plots and in PecletâThiele diagrams. Moreover, the study also yielded new results for the nonlinear reactionâdiffusion problem in a curved membrane with its two surfaces exposed to different concentrations, a case of relevance in membrane reactors
GestĂŁo de infestantes de inverno e primavera em vinha e olival com um fertilizante ecolĂłgico com propriedades herbicidas
Weeds reduce crop yields and require annual measures of control, although they can provide important ecological benefits. In this work, the
efficacy was tested of an ecological fertilizer with herbicidal properties (Bioscrop HerbitecÂź) which in high concentrations (10-15%) can have a
similar effect to a contact herbicide. The composition of the product is 6.0 % of water-soluble potassium oxide, 54.7 % of organic acids and 39.3
% of dispersants and diluents. The product was tested in six field trials during two years, which included two vineyards and two olive orchards
and winter and spring vegetation. In each experiment three treatments were imposed, being the product applied at the concentrations of 10% and
15% and a non-treated control. In treated plots, the entire ground surface (rows and inter-rows) was sprayed. The evaluation of the effect of the
treatments on vegetation was assessed by the pin point and grid methods which consisted of determining the percentage of damaged and not
damaged vegetation and bare soil. The production of dry biomass of weeds was also evaluated as a measure of the persistence of the damage on
vegetation. The floristic composition of the stands was also recorded to evaluate the specific susceptibility of the weeds to the different treatments.
The results showed that the product severely damaged the vegetation, and the effect persisted for more than a month. The application of the
product caused a severe reduction in the aboveground biomass while keeping the soil protected, showing a useful compromise between the
reduction in weed competition and the maintenance of ground cover. Some species were severely damaged while others seemed to have benefited
in relative terms, suggesting that the effectiveness of the product will be dependent on the weed species present.As infestantes reduzem a produtividade das culturas e requerem medidas anuais de combate, embora também possam fornecer importantes
serviços ecossistémicos. Neste trabalho foi testada a eficåcia de um produto ecológico (Bioscrop HerbitecŸ) que, em altas concentraçÔes (10-
15%), pode ter um efeito semelhante ao de um herbicida de contato. O produto contĂ©m 6,0 % de Ăłxido de potĂĄssio solĂșvel em ĂĄgua, 54,7 % de
ĂĄcidos orgĂąnicos e 39,3 % de dispersantes e diluentes. O produto foi testado em seis ensaios de campo, em duas vinhas e dois olivais e sobre
vegetação de inverno e de primavera. Em cada ensaio foram testados trĂȘs tratamentos, correspondentes Ă aplicação do produto em duas
concentraçÔes (10 e 15%) e uma modalidade testemunha. Nos talhÔes tratados o produto foi aplicado nas linhas e entrelinhas. O efeito dos
tratamentos na vegetação foi avaliado pelos métodos do ponto quadrado e da grelha, que consistiram em determinar o grau de cobertura do solo
com vegetação danificada, nĂŁo danificada e solo nu. A produção de matĂ©ria seca das infestantes foi tambĂ©m avaliada como medida da persistĂȘncia
do dano na vegetação. A composição florĂstica dos cobertos foi tambĂ©m registada como forma de avaliar a suscetibilidade especĂfica das
infestantes aos diferentes tratamentos. Os resultados mostraram que o produto danificou severamente a vegetação e o efeito persistiu por mais de
um mĂȘs. A aplicação do produto causou uma redução significativa da biomassa aĂ©rea, mas manteve o solo protegido, mostrando um equilĂbrio
interessante entre a redução da competição das infestantes e a proteção do solo. Algumas espécies foram fortemente danificadas, enquanto outras
parecem ter beneficiado em termos relativos, sugerindo que a eficåcia do produto dependerå das espécies infestantes presentesThe authors are grateful to the Foundation for Science and Technology (FCT, Portugal) and FEDER under Programme PT2020 for financial support to CIMO (UID/AGR/00690/2013).
The results of the first year of studies of this work were extracted from the master's thesis in Agroecology of the first author (AntĂłnio Barreira)info:eu-repo/semantics/publishedVersio
QCD-supression by Black Hole Production at the LHC
Possible consequences of the production of small black holes at the LHC for
different scenarios with large extra dimensions are investigated. The effects
from black hole production on some standard jet observables are examined,
concentrating on the reduction of the QCD cross section. It is found that black
hole production of partons interacting on a short enough distance indeed seem
to generate a drastic drop in the QCD cross section. However from an
experimental point of view this will in most cases be camouflaged by energetic
radiation from the black holes
Operational Observatory of the catalan sea (OOCS)
The Operational Observatory of the Catalan Sea (OOCS) recently created
by the Operational Oceanography Group at CEAB-CSIC is presented. The OOCS aims
at performing observations of the marine environment in the Catalan Sea and beyond,
assessing, modelling and forecasting the hydrodynamic and biogeochemical
processes of the region. Some of the biogeochemical variables available in the models
and forecast are phytoplankton, zooplankton and nutrients. Although OOCS is
expected to be fully operational in 2011, some of its services are already available to
the public through a dedicated webpage http://www.ceab.csic.es/~simob/.Peer Reviewe
Gametic and somatic embryogenesis through in vitro anther culture of different Citrus genotypes
Abstract: In vitro tissue culture represents a useful technique for advancing Citrus breeding and propagation. Among in vitro regeneration systems, anther culture is commonly used to produce haploids and doubled haploids for a fast-track producing homozygous lines, in comparison with the traditional self-pollination approach, which involves several generations of selfing. In addition, anthers culture can produce somatic embryos that can also be used for clonal propagation. In this study, two thermal shocks were applied to the anthers of six Citrus genotypes (two clementine and four sweet oranges), just after they were put in culture. The response obtained was different depending on the genotype: both clementines, namely Hernandina and Corsica, produced homozygous and triploid regenerants (microspore-derived embryos), whereas all of the analyzed regenerants from sweet oranges, three cultivars of Tarocco and Moro, produced heterozygous and diploid regenerants similar to the parental genotypes (somatic embryos)
High correlation between Chagas' disease serology and PCR-based detection of Trypanosoma cruzi kinetoplast DNA in bolivian children living in an endemic area
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Previous issue date: 1994Fundação Oswaldo Cruz. Instituto Oswaldo Cruz. Departamento de BioquĂmica e Biologia Molecular. LaboratĂłrio de Biologia Molecular e Doenças EndĂȘmicas. Rio de Janeiro, RJ, Brasil.UMR CNRS/ ORSTOM, GĂ©nĂ©tique MolĂ©culaire des Parasites et des Vecteurs. CP 9214, La Paz, Bolivia.Fundação Oswaldo Cruz. Instituto Oswaldo Cruz. Departamento de BioquĂmica e Biologia Molecular. LaboratĂłrio de Biologia Molecular e Doenças EndĂȘmicas. Rio de Janeiro, RJ, Brasil.Universidad Mayor de San Andres. Instituto Boliviano de Biologia de Altura. La Paz, Bolivia.Fundação Oswaldo Cruz. Instituto Oswaldo Cruz. Departamento de BioquĂmica e Biologia Molecular. LaboratĂłrio de Biologia Molecular e Doenças EndĂȘmicas. Rio de Janeiro, RJ, Brasil.Fundação Oswaldo Cruz. Instituto Oswaldo Cruz. Departamento de BioquĂmica e Biologia Molecular. LaboratĂłrio de Biologia Molecular e Doenças EndĂȘmicas. Rio de Janeiro, RJ, Brasil.UMR CNRS/ ORSTOM, GĂ©nĂ©tique MolĂ©culaire des Parasites et des Vecteurs. CP 9214, La Paz, Bolivia.The detection of Tr)tpunosomu crirzi kinetoplast DNA by polymerase chain reaction (PCR) amplification is a potentially
powerful tool for the parasitological diagnosis of Chagasâ disease. We have applied this technique in a field situation in Bolivia,
where 45 children from a primary school were subjected to serological testing, buffy coat analysis and PCR diagnosis. 26 of the 28
serology-positive individuals were also positive by PCR. In addition, two serology-negative children gave a positive result by PCR,
including one who was positive in the buffy coat test. These results suggest that PCR detection of T. cruzi DNA in blood can be a
very useful complement to serology in Chagasâ disease diagnosis in Bolivia
Power transformers winding fault diagnosis by the on-load exciting current extended Park's vector approach
This paper presents the application of the on-load exciting current Extended Park's Vector Approach to diagnose incipient turn-to-turn winding faults in operating power transformers. Experimental and simulation test results demonstrate the effectiveness of the proposed technique, which is based on the spectral analysis of the AC component of the on-load exciting current Park's Vector modulus
Nonequilibrium wetting
When a nonequilibrium growing interface in the presence of a wall is
considered a nonequilibrium wetting transition may take place. This transition
can be studied trough Langevin equations or discrete growth models. In the
first case, the Kardar-Parisi-Zhang equation, which defines a very robust
universality class for nonequilibrium moving interfaces, with a soft-wall
potential is considered. While in the second, microscopic models, in the
corresponding universality class, with evaporation and deposition of particles
in the presence of hard-wall are studied. Equilibrium wetting is related to a
particular case of the problem, it corresponds to the Edwards-Wilkinson
equation with a potential in the continuum approach or to the fulfillment of
detailed balance in the microscopic models. In this review we present the
analytical and numerical methods used to investigate the problem and the very
rich behavior that is observed with them.Comment: Review, 36 pages, 16 figure
- âŠ