632 research outputs found
History-sensitive versus future-sensitive approaches to security in distributed systems
We consider the use of aspect-oriented techniques as a flexible way to deal
with security policies in distributed systems. Recent work suggests to use
aspects for analysing the future behaviour of programs and to make access
control decisions based on this; this gives the flavour of dealing with
information flow rather than mere access control. We show in this paper that it
is beneficial to augment this approach with history-based components as is the
traditional approach in reference monitor-based approaches to mandatory access
control. Our developments are performed in an aspect-oriented coordination
language aiming to describe the Bell-LaPadula policy as elegantly as possible.
Furthermore, the resulting language has the capability of combining both
history- and future-sensitive policies, providing even more flexibility and
power.Comment: In Proceedings ICE 2010, arXiv:1010.530
“Please sir, can I have some more?” A Quantitative study into the Impact of the COVID-19 Pandemic on People with Specific Dietary Requirements
The first cases of a new SARS virus SARS-cov-2 were identified in the Chinese city of Wuhan at the end of 2019 and its subsequent spread across the globe lead the World Health organisation to declare a pandemic on the 11th March 2020. In order to help control the spread of the virus, the UK government introduced its first national lockdown on the 23rd March 2020. The aim of the lockdown was to reduce the transmission of the virus, thus reducing the number of cases, which would in turn reduce the pressure on the National Health Service (NHS) by having fewer people hospitalised and limiting the number of fatalities due to COVID-19. This lockdown closed all non-essential businesses and only allowed citizens to leave their home for essential purposes, such as food shopping and an hour of exercise every day.
Whilst undoubtedly this lockdown was successful in reducing the number of COVID-19 cases in the country, it did in itself give rise to a number of significant Public Health issues: mental health services saw an increase in service users as a result of increased social isolation, depression and people worrying about food insecurity and food poverty. In particular, issues arising from food insecurities and food poverty were exasperated due to school closures and home schooling which initially meant there was no access to the free school meal system. However, within this there were significant hidden risks for those with specific dietary requirements, especially in the early stages of COVID-19 pandemic
Information Security as Strategic (In)effectivity
Security of information flow is commonly understood as preventing any
information leakage, regardless of how grave or harmless consequences the
leakage can have. In this work, we suggest that information security is not a
goal in itself, but rather a means of preventing potential attackers from
compromising the correct behavior of the system. To formalize this, we first
show how two information flows can be compared by looking at the adversary's
ability to harm the system. Then, we propose that the information flow in a
system is effectively information-secure if it does not allow for more harm
than its idealized variant based on the classical notion of noninterference
Casimir micro-sphere diclusters and three-body effects in fluids
Our previous article [Phys. Rev. Lett. 104, 060401 (2010)] predicted that
Casimir forces induced by the material-dispersion properties of certain
dielectrics can give rise to stable configurations of objects. This phenomenon
was illustrated via a dicluster configuration of non-touching objects
consisting of two spheres immersed in a fluid and suspended against gravity
above a plate. Here, we examine these predictions from the perspective of a
practical experiment and consider the influence of non-additive, three-body,
and nonzero-temperature effects on the stability of the two spheres. We
conclude that the presence of Brownian motion reduces the set of experimentally
realizable silicon/teflon spherical diclusters to those consisting of layered
micro-spheres, such as the hollow- core (spherical shells) considered here.Comment: 11 pages, 9 figure
A shallow layer model for heavy gas dispersion from natural sources: application and hazard assessment at Caldara di Manziana, Italy.
Several non-volcanic sources in central Italy emit a large amount of carbon dioxide (CO2). Under
stable atmospheric conditions and/or in presence of topographic depressions, the concentration of
CO2, which has a molecular mass greater than that of air, can reach high values that are lethal to
humans or animals. Several episodes of this phenomenon were recorded in central Italy and
elsewhere. In order to validate a model for the dispersion of a heavy gas and to assess the
consequent hazard, we applied and tested the code TWODEE-2, an improved version of the
established TWODEE model, which is based on a shallow layer approach that uses depth-averaged
variables to describe the flow behavior of dense gas over complex topography. We present results
for a vented CO2 release at Caldara di Manziana in central Italy. We find that the model gives
reliable results when the input quantity can be properly defined. Moreover, we show that the
model can be a useful tool for gas hazard assessment, by evaluating where and when lethal
concentrations for humans and animal are reached.Several non-volcanic sources in central Italy emit a large amount of carbon dioxide (CO2). Under
stable atmospheric conditions and/or in presence of topographic depressions, the concentration of
CO2, which has a molecular mass greater than that of air, can reach high values that are lethal to
humans or animals. Several episodes of this phenomenon were recorded in central Italy and
elsewhere. In order to validate a model for the dispersion of a heavy gas and to assess the
consequent hazard, we applied and tested the code TWODEE-2, an improved version of the
established TWODEE model, which is based on a shallow layer approach that uses depth-averaged
variables to describe the flow behavior of dense gas over complex topography. We present results
for a vented CO2 release at Caldara di Manziana in central Italy. We find that the model gives
reliable results when the input quantity can be properly defined. Moreover, we show that the
model can be a useful tool for gas hazard assessment, by evaluating where and when lethal
concentrations for humans and animal are reached.Several non-volcanic sources in central Italy emit a large amount of carbon dioxide (CO2). Under
stable atmospheric conditions and/or in presence of topographic depressions, the concentration of
CO2, which has a molecular mass greater than that of air, can reach high values that are lethal to
humans or animals. Several episodes of this phenomenon were recorded in central Italy and
elsewhere. In order to validate a model for the dispersion of a heavy gas and to assess the
consequent hazard, we applied and tested the code TWODEE-2, an improved version of the
established TWODEE model, which is based on a shallow layer approach that uses depth-averaged
variables to describe the flow behavior of dense gas over complex topography. We present results
for a vented CO2 release at Caldara di Manziana in central Italy. We find that the model gives
reliable results when the input quantity can be properly defined. Moreover, we show that the
model can be a useful tool for gas hazard assessment, by evaluating where and when lethal
concentrations for humans and animal are reached.Several non-volcanic sources in central Italy emit a large amount of carbon dioxide (CO2). Under
stable atmospheric conditions and/or in presence of topographic depressions, the concentration of
CO2, which has a molecular mass greater than that of air, can reach high values that are lethal to
humans or animals. Several episodes of this phenomenon were recorded in central Italy and
elsewhere. In order to validate a model for the dispersion of a heavy gas and to assess the
consequent hazard, we applied and tested the code TWODEE-2, an improved version of the
established TWODEE model, which is based on a shallow layer approach that uses depth-averaged
variables to describe the flow behavior of dense gas over complex topography. We present results
for a vented CO2 release at Caldara di Manziana in central Italy. We find that the model gives
reliable results when the input quantity can be properly defined. Moreover, we show that the
model can be a useful tool for gas hazard assessment, by evaluating where and when lethal
concentrations for humans and animal are reached.Several non-volcanic sources in central Italy emit a large amount of carbon dioxide (CO2). Under
stable atmospheric conditions and/or in presence of topographic depressions, the concentration of
CO2, which has a molecular mass greater than that of air, can reach high values that are lethal to
humans or animals. Several episodes of this phenomenon were recorded in central Italy and
elsewhere. In order to validate a model for the dispersion of a heavy gas and to assess the
consequent hazard, we applied and tested the code TWODEE-2, an improved version of the
established TWODEE model, which is based on a shallow layer approach that uses depth-averaged
variables to describe the flow behavior of dense gas over complex topography. We present results
for a vented CO2 release at Caldara di Manziana in central Italy. We find that the model gives
reliable results when the input quantity can be properly defined. Moreover, we show that the
model can be a useful tool for gas hazard assessment, by evaluating where and when lethal
concentrations for humans and animal are reached
A shallow-layer model for heavy gas dispersion from natural sources: Application and hazard assessment at Caldara di Manziana, Italy
Several nonvolcanic sources in central Italy emit a large amount of carbon dioxide (CO2). Under stable
atmospheric conditions and/or in the presence of topographic depressions, the concentration of CO2, which
has a molecular mass greater than that of air, can reach high values that are lethal to humans or animals.
Several episodes of this phenomenon were recorded in central Italy and elsewhere. In order to validate a
model for the dispersion of a heavy gas and to assess the consequent hazard, we applied and tested the code
TWODEE-2, an improved version of the established TWODEE model, which is based on a shallow-layer
approach that uses depth-averaged variables to describe the flow behavior of dense gas over complex
topography. We present results for a vented CO2 release at Caldara di Manziana in central Italy. We find
that the model gives reliable results when the input quantity can be properly defined. Moreover, we show
that the model can be a useful tool for gas hazard assessment by evaluating where and when lethal
concentrations for humans and animals are reached
Long-lived photoexcited states in polydiacetylenes with different molecular and supramolecular organization
With the aim of determining the importance of the molecular and supramolecular organization on the excited states of polydiacetylenes, we have studied the photoinduced absorption spectra of the red form of poly[1,6-bis(3,6-didodecyl-N-carbazolyl)-2,4-hexadiyne] (polyDCHD-S) and the results compared with those of the blue form of the same polymer. An interpretation of the data is given in terms of both the conjugation length and the interbackbone separation also in relation to the photoinduced absorption spectra of both blue and red forms of poly[1,6-bis(N-carbazolyl)-2,4-hexadiyne] (polyDCHD), which does not carry the alkyl substituents on the carbazolyl side groups. Information on the above properties is derived from the analysis of the absorption and Raman spectra of this class of polydiacetylenes
Pedestrian, Crowd, and Evacuation Dynamics
This contribution describes efforts to model the behavior of individual
pedestrians and their interactions in crowds, which generate certain kinds of
self-organized patterns of motion. Moreover, this article focusses on the
dynamics of crowds in panic or evacuation situations, methods to optimize
building designs for egress, and factors potentially causing the breakdown of
orderly motion.Comment: This is a review paper. For related work see http://www.soms.ethz.c
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