4,193 research outputs found
Anisotropic Lifshitz Point at
We present the critical exponents , and
for an -axial Lifshitz point at second order in an expansion.
We introduced a constraint involving the loop momenta along the -dimensional
subspace in order to perform two- and three-loop integrals. The results are
valid in the range . The case corresponds to the usual
Ising-like critical behavior.Comment: 10 pages, Revte
Environmental risk evaluation of potential toxic elements in stream sediments – Monfortinho area (Central Portugal)
Os elementos potencialmente tóxicos (EPT) em sedimentos de corrente constituem uma importante ferramenta na avaliação do risco ambiental na influência de depósitos minerais. A região de Monfortinho está localizada na bacia hidrográfica do rio Erges, que faz fronteira com Espanha. Desde a época romana, que se conhecem evidências da exploração de ouro sedimentar nesta região do país, a qual tem vindo a desaparecer ao longo do tempo. Na avaliação da distribuição espacial de EPT selecionados – As, B, Ba, Cd, Cu, Fe, Ni, Pb, V e Zn - foram analisadas 217 amostras de sedimentos de corrente. Os sedimentos de corrente mostram uma elevada variabilidade na concentração dos EPT, podendo concluir-se que os valores mais elevados se relacionam com as mineralizações de Au na região de Monfortinho, bem como, com as de Sn-W que ocorrem nas proximidades. A maioria dos EPT apresenta um fator de contaminação moderado, embora para o Ba, Cr e B este seja elevado a muito elevado; o que se reflete num grau de contaminação moderado a elevado para a área de estudo. Na influência dos vários EPT, a maioria da área mostra um índice de resposta à toxicidade baixo, embora em 5% das amostras este seja moderado.Potentially toxic elements (PTE) of stream sediments are an important tool in environmental risk assessment associated with
mineralized deposits. εonfortinho is in the watershed of the Erges river, a transboundary river with Spain. Since Roman period,
there is evidence of sedimentary gold exploitation in this region, which has ceased over time. To define a spatial distribution of
selected PTE - As, B, Ba, Cd, Cu, Fe, Ni, Pb, V and Zn - β17 samples of stream sediments were analysed. Stream sediments
show a high PTE contents variability, suggesting that the highest values are related to the Au mineralization in εonfortinho, as
well as the Sn-→ mineralization’s around the study area. Almost stream sediments show a moderate PTE contamination factor,
although for Ba, Cr and B has a very high contamination; which is reflected in a moderate to high degree of contamination in the
area. All the PTE contribution indicate a low toxic response index for the area, although for 5% of stream sediments indicate a
moderate associated toxicity.Os autores agradecem ao δNEG (atual
representante dos Serviços Geológicos de
Portugal) pela cedência dos dados. Este
trabalho foi desenvolvido no âmbito do ICT
– Universidade do εinho (Braga).info:eu-repo/semantics/publishedVersio
Deep shower interpretation of the cosmic ray events observed in excess of the Greisen-Zatsepin-Kuzmin energy
We consider the possibility that the ultra-high-energy cosmic ray flux has a
small component of exotic particles which create showers much deeper in the
atmosphere than ordinary hadronic primaries. It is shown that applying the
conventional AGASA/HiRes/Auger data analysis procedures to such exotic events
results in large systematic biases in the energy spectrum measurement. SubGZK
exotic showers may be mis-reconstructed with much higher energies and mimick
superGZK events. Alternatively, superGZK exotic showers may elude detection by
conventional fluorescence analysis techniques.Comment: 22 pages, 5 figure
Is secure coding education in the industry needed? An investigation through a large scale survey
The Department of Homeland Security in the United States estimates that 90% of software vulnerabilities can be traced back to defects in design and software coding. The financial impact of these vulnerabilities has been shown to exceed 380 million USD in industrial control systems alone. Since software developers write software, they also introduce these vulnerabilities into the source code. However, secure coding guidelines exist to prevent software developers from writing vulnerable code. This study focuses on the human factor, the software developer, and secure coding, in particular secure coding guidelines. We want to understand the software developers' awareness and compliance to secure coding guidelines and why, if at all, they aren't compliant or aware. We base our results on a large-scale survey on secure coding guidelines, with more than 190 industrial software developers. Our work's main contribution motivates the need to educate industrial software developers on secure coding guidelines, and it gives a list of fifteen actionable items to be used by practitioners in the industry. We also make our raw data openly available for further research.info:eu-repo/semantics/acceptedVersio
Hydrogeochemical assessment of termal water in fractured rocks – a Portuguese case study
The thermal Fadagosa-Nisa water is located at north Alentejo (Portugal) and it is important in the economy of this region. The studied area is in a predominantly fractured granite and the water circulation is characteristic of fissured media, with a productivity of 2 L/s from a single well. Water hydrogeochemistry results revealed a mineralized water, with an electrical conductivity of 454 µS/cm and a total mineralization of 310 mg/L, neutral (pH=7.9-8.0) and a temperature of 19ºC. The thermal water has a dominant hydrogeochemical sodium-bicarbonate facies, with a fluoride (F-=9.6 mg/L) and hydrogen sulphide content (HS=15.2 mg/L), and moderate amounts of silica (SiO2=34.0 mg/L). The low nitrate (NO3-=0.1 mg/L) and sulphate (SO42-=1.6-5.2 mg/L) contents support the low vulnerability associated to the groundwater catchment. No significant seasonal changes have been found in the Fadagosa-Nisa thermal groundwater composition, suggesting a hydrogeochemical stability to the area. The regular hydrogeochemical results is in accordance to the low vulnerability obtained by the application of DRASTIC index in the Fadagosa-Nisa area.Institute of Earth Sciences (ICT), under
contracts UID/GEO/04683/2013 with FCT (the Portuguese Science and Technology Foundation)info:eu-repo/semantics/publishedVersio
Awareness of secure coding guidelines in the industry - A first data analysis
Software needs to be secure, in particular when deployed to critical infrastructures. Secure coding guidelines capture practices in industrial software engineering to ensure the security of code. This study aims at assessing the level of awareness of secure coding in industrial software engineering, the skills of software developers to spot weaknesses in software code, and avoid them, as well as the organizational support to adhere to coding guidelines. The approach draws not only on well-established theories of policy compliance, neutralization theory, and security-related stress but also on the authors’ many years of experience in industrial software engineering and on lessons identified from training secure coding in the industry. The paper presents the design of the questionnaire for the online survey and the first analysis of data from the pilot study.info:eu-repo/semantics/acceptedVersio
Astrophysical Neutrino Event Rates and Sensitivity for Neutrino Telescopes
Spectacular processes in astrophysical sites produce high-energy cosmic rays
which are further accelerated by Fermi-shocks into a power-law spectrum. These,
in passing through radiation fields and matter, produce neutrinos. Neutrino
telescopes are designed with large detection volumes to observe such
astrophysical sources. A large volume is necessary because the fluxes and
cross-sections are small. We estimate various telescopes' sensitivities and
expected event rates from astrophysical sources of high-energy neutrinos. We
find that an ideal detector of km^2 incident area can be sensitive to a flux of
neutrinos integrated over energy from 10^5 and 10^{7} GeV as low as 1.3 *
10^(-8) * E^(-2) (GeV/cm^2 s sr) which is three times smaller than the
Waxman-Bachall conservative upper limit on potential neutrino flux. A real
detector will have degraded performance. Detection from known point sources is
possible but unlikely unless there is prior knowledge of the source location
and neutrino arrival time.Comment: Section added +modification
Spatio-temporal vulnerability assessment in fractured groundwater systems
Governance reforms are required to demonstrate adaptive and resilient urban water resource management that considers complexity, uncertainty in immediate and long term change. Contamination of groundwater is a complex process and full of uncertainty at local and regional scale. The main objective of this research is the study of vulnerability to pollution in an unconfined karstic aquifer. Mainly it is addressed vulnerability integration, in relation to policy, specifically in risk evaluation and risk–benefit considerations. Development of an integrated vulnerability assessment methodology can be useful to effectively manage and protect this valuable freshwater source. The research insights suggest that the establishment of a pattern of effective governance is mandatory as the future highway, the prison and the airport are overlaying the most vulnerable areas of the aquifer and therefore provide policy makers guidance in overcoming urban water governance challenges.info:eu-repo/semantics/publishedVersio
Papel da nutrição sobre a reprodução ovina.
Trabalho apresentado nos Anais do VII Congresso Norte Nordeste de Reprodução Anima (CONERA), Mossoró, maio, 2014
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