3,347 research outputs found
Remote sensing as an aid to route evaluation for relocated Louisiana Highway 1
Aerial photography in the form of color infrared and color positive transparencies was used as an aid for evaluation of the route proposed for relocated Louisiana Highway 1, between LaRose and Golden Meadows, in South Louisiana
Remote sensing as an aid to route evaluation for relocated Louisiana Highway 1
NASA aerial photography in the form of color infrared and color positive transparencies is used as an aid for evaluation of the route proposed for relocated Louisiana Highway 1, between LaRose and Golden Meadow, in South Louisiana
On the Nature of the Cosmological Constant Problem
General relativity postulates the Minkowski space-time to be the standard
flat geometry against which we compare all curved space-times and the
gravitational ground state where particles, quantum fields and their vacuum
states are primarily conceived. On the other hand, experimental evidences show
that there exists a non-zero cosmological constant, which implies in a deSitter
space-time, not compatible with the assumed Minkowski structure. Such
inconsistency is shown to be a consequence of the lack of a application
independent curvature standard in Riemann's geometry, leading eventually to the
cosmological constant problem in general relativity.
We show how the curvature standard in Riemann's geometry can be fixed by
Nash's theorem on locally embedded Riemannian geometries, which imply in the
existence of extra dimensions. The resulting gravitational theory is more
general than general relativity, similar to brane-world gravity, but where the
propagation of the gravitational field along the extra dimensions is a
mathematical necessity, rather than being a a postulate. After a brief
introduction to Nash's theorem, we show that the vacuum energy density must
remain confined to four-dimensional space-times, but the cosmological constant
resulting from the contracted Bianchi identity is a gravitational contribution
which propagates in the extra dimensions. Therefore, the comparison between the
vacuum energy and the cosmological constant in general relativity ceases to be.
Instead, the geometrical fix provided by Nash's theorem suggests that the
vacuum energy density contributes to the perturbations of the gravitational
field.Comment: LaTex, 5 pages no figutres. Correction on author lis
The LOFT (Large Observatory for X-ray Timing) background simulations
The Large Observatory For X-ray Timing (LOFT) is an innovative medium-class
mission selected for an assessment phase in the framework of the ESA M3 Cosmic
Vision call. LOFT is intended to answer fundamental questions about the
behaviour of matter in the very strong gravitational and magnetic fields around
compact objects. With an effective area of ~10 m^2 LOFT will be able to measure
very fast variability in the X-ray fluxes and spectra. A good knowledge of the
in-orbit background environment is essential to assess the scientific
performance of the mission and to optimize the instrument design. The two main
contributions to the background are cosmic diffuse X-rays and high energy
cosmic rays; also, albedo emission from the Earth is significant. These
contributions to the background for both the Large Area Detector and the Wide
Field Monitor are discussed, on the basis of extensive Geant-4 simulations of a
simplified instrumental mass model.Comment: Proceedings of SPIE, Vol. 8443, Paper No. 8443-209, 201
Análise do perfil de adsorção das enzimas envolvidas na sacarificação enzimática de diferentes bagaços de cana-de-açúcar pré-tratados com sulfito ácido
A produção de etanol de segunda geração é uma realidade brasileira que já vem sendo implementada na indústria. Porém, vários fatores que governam a sacarificação enzimática de materiais lignocelulósicos ainda necessitam ser melhor esclarecidos, de forma a baixar o custo e aumentar o rendimento final de monossacarídeos. A adsorção das enzimas durante a sacarificação da celulose é um fator determinante para uma hidrólise eficiente, que pode ser influenciada pelas características do substrato lignocelulósico, como conteúdo ou distribuição de hemicelulose e lignina. Diante disso, este trabalho teve como objetivo avaliar o perfil de adsorção das enzimas envolvidas na sacarificação do bagaço de cana-de-açúcar pré-tratado com sulfito ácido em diferentes temperaturas. Os resultados revelaram que a adsorção varia com as características finais dos substratos gerados, como o teor de lignina remanescente e a quantidade de grupos sulfônicos
Phenex: Ontological Annotation of Phenotypic Diversity
Phenex is a platform-independent desktop application designed to facilitate efficient and consistent annotation of phenotypic variation using Entity-Quality syntax, drawing on terms from community ontologies for anatomical entities, phenotypic qualities, and taxonomic names. Despite the centrality of the phenotype to so much of biology, traditions for communicating information about phenotypes are idiosyncratic to different disciplines. Phenotypes seem to elude standardized descriptions due to the variety of traits that compose them and the difficulty of capturing the complex forms and subtle differences among organisms that we can readily observe. Consequently, phenotypes are refractory to attempts at data integration that would allow computational analyses across studies and study systems. Phenex addresses this problem by allowing scientists to employ standard ontologies and syntax to link computable phenotype annotations to evolutionary character matrices, as well as to link taxa and specimens to ontological identifiers. Ontologies have become a foundational technology for establishing shared semantics, and, more generally, for capturing and computing with biological knowledge
Experimental Study on the Explosive Spalling in High-Performance Concrete: Role of Aggregate and Fiber Types
A complete description of the mechanical behavior of High-Performance Concrete in fire still requires further efforts to fully understand the tricky phenomenon of spalling, whose complexity comes from the interaction among different phenomena, namely: the microstructural changes occurring in concrete at high temperature, the pressure rising in the pores, and the stress induced by both thermal gradients and external loads. To what extent these different aspects influence each other is still not completely clear, and within this context a comprehensive experimental campaign has been launched at the Politecnico di Milano, focusing on the role played by concrete grade, aggregate type, and fiber type and content. Eleven concrete mixes are investigated considering three grades (fc ≥ 40, 60 and 90 MPa), three aggregate types (silico-calcareous, basalt and calcareous aggregates) and different fiber types and contents (steel and monofilament or fibrillated polypropylene fibers)
Influência de diferentes fontes de adubos nitrogenados na produção de grãos e nos crescimento de ramos de cafeeiro Conilon.
Com o objetivo de avaliar a influência de cinco fontes de adubos nitrogenados no crescimento de ramos e na produção de grãos do cafeeiro Conilon (Coffea canephora), foram comparados uréia perolada; Uréia + NBPT; uréia + 0,15% de cobre e 0,4% de boro; uréia (37%) + enxofre (17%) e nitrato de amônio. O estudo foi realizado no município de Nova Venécia - ES em uma lavoura de cafeeiro Conilon ?Vitória INCAPER 8142? clone 03 com espaçamento de três metros entre linhas e um metro entre plantas, em estádio de segundo ano de produção, seguindo o delineamento em blocos casualizados. Foi avaliado o crescimento dos ramos ortotrópicos e dos ramos plagiotrópicos em nove avaliações mensais. A produtividade do cafeeiro foi obtida em litros por planta de café maduro e extrapolada para sacas por hectare. Observou-se que não houve diferença estatística entre as diferentes fontes de adubos nitrogenados no crescimento de ramos do cafeeiro. Em relação à produtividade, observou-se que os tratamentos com uréia + 0,15% de cobre + 0,4% de boro e o tratamento com uréia (37%) + enxofre (17%) apresentaram maior produção de grãos do cafeeiro
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