6,577 research outputs found
Extending the ADM formalism to Weyl geometry
In order to treat quantum cosmology in the framework of Weyl spacetimes we
take the first step of extending the Arnowitt-Deser-Misner formalism to Weyl
geometry. We then obtain an expression of the curvature tensor in terms of
spatial quantities by splitting spacetime in (3+1)-dimensional form. We next
write the Lagrangian of the gravitation field based in Weyl-type gravity
theory. We extend the general relativistic formalism in such a way that it can
be applied to investigate the quantum cosmology of models whose spacetimes are
endowed with a Weyl geometrical structure.Comment: 10 page
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A design framework for enabling sustainability in the clothing sector
This article discusses general strategies to enable environmental sustainability within the clothing sector, providing a framework for decision makers involved in the development of programs and policies for this sector. It initially revises the environmental impact of the clothing system and determines its key environmental sustainability priorities. The framework involves five evolutionary strategies for enabling sustainable consumption and production: 1) environmental improvement of flows throughout the supply chain; 2) environmental redesign of existing clothes; 3) design of new clothes intrinsically more sustainable; 4) design of cloth-service systems and 5) promoting life styles towards sufficient consumption. The practical implications of each strategy is analysed based on correspondent ex-post-facto case studies identified in Brazil, using data collected through literature review and desktop research
A Framework for Efficient Adaptively Secure Composable Oblivious Transfer in the ROM
Oblivious Transfer (OT) is a fundamental cryptographic protocol that finds a
number of applications, in particular, as an essential building block for
two-party and multi-party computation. We construct a round-optimal (2 rounds)
universally composable (UC) protocol for oblivious transfer secure against
active adaptive adversaries from any OW-CPA secure public-key encryption scheme
with certain properties in the random oracle model (ROM). In terms of
computation, our protocol only requires the generation of a public/secret-key
pair, two encryption operations and one decryption operation, apart from a few
calls to the random oracle. In~terms of communication, our protocol only
requires the transfer of one public-key, two ciphertexts, and three binary
strings of roughly the same size as the message. Next, we show how to
instantiate our construction under the low noise LPN, McEliece, QC-MDPC, LWE,
and CDH assumptions. Our instantiations based on the low noise LPN, McEliece,
and QC-MDPC assumptions are the first UC-secure OT protocols based on coding
assumptions to achieve: 1) adaptive security, 2) optimal round complexity, 3)
low communication and computational complexities. Previous results in this
setting only achieved static security and used costly cut-and-choose
techniques.Our instantiation based on CDH achieves adaptive security at the
small cost of communicating only two more group elements as compared to the
gap-DH based Simplest OT protocol of Chou and Orlandi (Latincrypt 15), which
only achieves static security in the ROM
Avaliação da resistĂȘncia de materiais comerciais de tomateiro a oito viroses que afetam a cultura no Brasil.
O objetivo deste trabalho foi avaliar a resistĂȘncia dos materiais de tomate palantados atualmente no paĂs a oito dos principais vĂrus que afetam a cultura.Suplemento. Edição dos resumos do 44Âș Congresso Brasileiro de Fitopatologia, 2011, Bento Gonçalves. Resumo 777
Risk factors for infection with Giardia duodenalis in pre-school children in the city of Salvador, Brazil.
A cross-sectional study of 694 children aged 2 to 45 months selected from 30 clusters throughout the city of Salvador, Bahia (pop. 2.3 million) was carried out as part of a longitudinal study of diarrhoea in order to identify risk factors for infection with Giardia duodenalis. Variables studied included three social and demographic factors (such as mother's education and marital status), five relating to the peri-domestic environment (rubbish disposal, open sewers, paving of the street), seven relating to the home itself (house construction, susceptibility to flooding, water supply and sanitation) as well as a score for hygiene behaviour based on structured observation. After multivariate analysis using a hierarchical model, only four significant risk factors were found: (a) number of children in the household under five years (b) rubbish not collected from the house (c) presence of visible sewage nearby, and (d) absence of a toilet. All four were significant at the 1% level
U B V R I Photometry of Stellar Structures throughout the Disk of the Barred Galaxy NGC 3367
We report new detailed surface U, B, V, R, and I photometry of 81 stellar
structures in the disk of the barred galaxy NGC 3367. The images show many
different structures indicating that star formation is going on in the most
part of the disk. NGC 3367 is known to have a very high concentration of
molecular gas distribution in the central regions of the galaxy and bipolar
synchrotron emission from the nucleus with two lobes (at 6 kpc) forming a
triple structure similar to a radio galaxy. We have determined the U, B, V, R,
and I magnitudes and U - B, B - V, U - V, and V - I colors for the central
region (nucleus), a region which includes supernovae 2003 AA, and 79 star
associations throughout NGC 3367. Estimation of ages of star associations is
very difficult due to several factors, among them: filling factor, metallicity,
spatial distribution of each structure and the fact that we estimated the
magnitudes with a circular aperture of 16 pixels in diameter, equivalent to
kpc. However, if the colors derived for NGC 3367 were similar to
the colors expected of star clusters with theoretical evolutionary star tracks
developed for the LMC and had a similar metallicity, NGC 3367 show 51 percent
of the observed structures with age type SWB I (few tens of Myrs), with seven
sources outside the bright surface brightness visible disk of NGC 3367.Comment: Accepted for publication (abr 2007) in The Astronomical Journal (July
2007 issue
More Discriminants with the Brezing-Weng Method
The Brezing-Weng method is a general framework to generate families of
pairing-friendly elliptic curves. Here, we introduce an improvement which can
be used to generate more curves with larger discriminants. Apart from the
number of curves this yields, it provides an easy way to avoid endomorphism
rings with small class number
Female Genital Mutilation: Knowledge from Health Professionals
Portugal is considered by the World Health Organization (WHO) a risk country for the practice of Female Genital Mutilation (FGM).
Objectives: To evaluate the knowledge that health professionals from Maternity Dr. Alfredo da Costa (MAC) have regarding FGM.
Population and Methods: Analysis of surveys delivered to health professionals from MAC (a hospital dedicated to reproductive health), between April and June 2008, addressing issues related to the knowledge about FGM.
Results: Authors collected 112 valid surveys involving 38 doctors, 48 nurses and 26 medical auxiliaries/administrative
personnel. From the respondents, 106 (95%) had heard about FMG practice before, the media being the most reported source of information; 59 (53%) replied they could be able to recognize FGM cases in their
clinical practice; however, only 31 (28%) claimed to know the FGM type classiication and 32 (29%) admitted to be prepared to recognize and manage these situations in their own clinical practice; 9 had been consulted explicitly by a FGM practice complication and 1 doctor had admitted having been asked to perform/execute FGM; 13
(12%) recognized that the Portuguese legislation its this practice. Regarding the practice of FGM, 100 (89%) of respondentes stated that it should not be maintained and 97 (87%) stated that it should not be tolerated. However, 42 (38%) considered that if these practices were a reality, then they should be medical assisted.
Discussion: Health professionals can play an important role in eliminating the practice of FGM, not only by the proper clinical management of this situation, but also by preventing those communities at risk to resort to FGM.
Most health professionals are not prepared to deal with FGM in their clinical practice. It is important to promote a better knowledge on the subject and to create protocols for proper clinical management
A typing error in Tokeshi's test of bimodality
Copyright © 2003 Blackwell PublishingâOne way to describe patterns of species distribution is to plot the frequency histograms using speciesârange-size data (Gaston, 1994; Brown, 1995; Gaston & Blackburn, 2000). Usually the untransformed geographical ranges of species are distributed following a âhollow curveâ, i.e. most species have narrow ranges and very few have widespread distributions. This highly âright-skewedâ curve has been regarded as unimodal (e.g. Gaston, 1994). In some cases, however, the species-range-size distribution shows a bimodal pattern (Hanski, 1982; Brown, 1984, 1995; Gaston, 1994; Gaston & Blackburn, 2000), in which to the left-hand mode is added a right hand mode generated by the widespread group of species that occur in almost all sampled sites. The âcore-satellite species hypothesisâ (Hanski, 1982) and the âresource usage modelâ (Brown, 1984, 1995) were proposed to explain the finding that a few species are regionally common (widespread) and locally abundant (the âcoreâ species in Hanskiâs model; the generalists or broad-niched species in Brownâs model), while most species can be regarded as having smaller ranges and low local abundances (the âsatelliteâ species in Hanskiâs model; the specialists or narrow-niched species in Brownâs model). [âŠ]
Aspectos agronĂŽmicos, fitopatolĂłgicos e socioeconĂŽmicos da sigatoka-negra na cultura da bananeira no Estado do AmapĂĄ
Sigatoka-negra da bananeira no AmapĂĄ: um desafio Ă pesquisa cientĂfica; A cultura da bananeira; Aspectos do melhoramento genĂ©tico da bananeira; Sigatoka-negra: aspectos fitopatolĂłgicos no AmapĂĄ; CaracterĂsticas fĂsico-quĂmicas de frutos de bananeiras resistentes Ă sigatoka-negra; Sigatoka-negra: repercussĂ”es socioeconĂŽmicas no Estado do AmapĂĄ; DinĂąmica no desempenho da capacidade produtiva da bananicultura amapaense.bitstream/item/84394/1/AP-2011-aspectos-agronomicos-fitopatologicos-bananeiras.pd
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