961 research outputs found
Updated global SMEFT fit to Higgs, diboson and electroweak data
The ATLAS and CMS collaborations have recently released significant new data on Higgs and diboson production in LHC Run 2. Measurements of Higgs properties have improved in many channels, while kinematic information for hâγγ and hâZZ can now be more accurately incorporated in fits using the STXS method, and W + W â diboson production at high p T gives new sensitivity to deviations from the Standard Model. We have performed an updated global fit to precision electroweak data, W + W â measurements at LEP, and Higgs and diboson data from Runs 1 and 2 of the LHC in the framework of the Standard Model Effective Field Theory (SMEFT), allowing all coefficients to vary across the combined dataset, and present the results in both the Warsaw and SILH operator bases. We exhibit the improvement in the constraints on operator coefficients provided by the LHC Run 2 data, and discuss the correlations between them. We also explore the constraints our fit results impose on several models of physics beyond the Standard Model, including models that contribute to the operator coefficients at the tree level and stops in the MSSM that contribute via loops
Quantitative Measurement of Cyber Resilience: Modeling and Experimentation
Cyber resilience is the ability of a system to resist and recover from a
cyber attack, thereby restoring the system's functionality. Effective design
and development of a cyber resilient system requires experimental methods and
tools for quantitative measuring of cyber resilience. This paper describes an
experimental method and test bed for obtaining resilience-relevant data as a
system (in our case -- a truck) traverses its route, in repeatable, systematic
experiments. We model a truck equipped with an autonomous cyber-defense system
and which also includes inherent physical resilience features. When attacked by
malware, this ensemble of cyber-physical features (i.e., "bonware") strives to
resist and recover from the performance degradation caused by the malware's
attack. We propose parsimonious mathematical models to aid in quantifying
systems' resilience to cyber attacks. Using the models, we identify
quantitative characteristics obtainable from experimental data, and show that
these characteristics can serve as useful quantitative measures of cyber
resilience.Comment: arXiv admin note: text overlap with arXiv:2302.04413,
arXiv:2302.0794
An Experimentation Infrastructure for Quantitative Measurements of Cyber Resilience
The vulnerability of cyber-physical systems to cyber attack is well known,
and the requirement to build cyber resilience into these systems has been
firmly established. The key challenge this paper addresses is that maturing
this discipline requires the development of techniques, tools, and processes
for objectively, rigorously, and quantitatively measuring the attributes of
cyber resilience. Researchers and program managers need to be able to determine
if the implementation of a resilience solution actually increases the
resilience of the system. In previous work, a table top exercise was conducted
using a notional heavy vehicle on a fictitious military mission while under a
cyber attack. While this exercise provided some useful data, more and higher
fidelity data is required to refine the measurement methodology. This paper
details the efforts made to construct a cost-effective experimentation
infrastructure to provide such data. It also presents a case study using some
of the data generated by the infrastructure.Comment: 6 pages, 2022 IEEE Military Communications Conference, pp. 855-86
Discrete or indiscrete? Redefining the colour polymorphism of the land snail Cepaea nemoralis
Biologists have long tried to describe and name the different phenotypes that make up the shell polymorphism of the land snail Cepaea nemoralis. Traditionally, the view is that the ground colour of the shell is one of a few major colour classes, either yellow, pink or brown, but in practise it is frequently difficult to distinguish the colours, and define different shades of the same colour. To understand whether colour variation is in reality continuous, and to investigate how the variation may be perceived by an avian predator, we applied psychophysical models of colour vision to shell reflectance measures. We found that both achromatic and chromatic variation are indiscrete in Cepaea nemoralis, being continuously distributed over many perceptual units. Nonetheless, clustering analysis based on the density of the distribution did reveal three groups, roughly corresponding to human-perceived yellow, pink and brown shells. We also found large-scale geographic variation in the frequency of these groups across Europe, and some covariance between shell colour and banding patterns. Although further studies are necessary, the observation of continuous variation in colour is intriguing because the traditional theory is that the underlying supergene that determines colour has evolved to prevent phenotypes from âdissolvingâ into continuous trait distributions. The findings thus have significance for understanding the Cepaea polymorphism, and the nature of the selection that acts upon it, as well as more generally highlighting the need to measure colour objectively in other systems
Cosmological thermodynamics and deflationary gas universe
We establish a general thermodynamic scheme for cosmic fluids with internal
self-interactions and discuss equilibrium and non-equilibrium aspects of such
systems in connection with (generalized) symmetry properties of the
cosmological dynamics. As an example we construct an exactly solvable gas
dynamical model of a ``deflationary'' transition from an initial de Sitter
phase to a subsequent Friedmann-Lema\^{\i}tre-Robertson-Walker (FLRW) period.
We demonstrate that this dynamics represents a manifestation of a conformal
symmetry of an ``optical'' metric, characterized by a specific effective
refraction index of the cosmic medium.Comment: 12 pages, to appear in PR
The effect of meteorological and chemical factors on the agreement between observations and predictions of fine aerosol composition in southwestern Ontario during BAQS-Met
The Border Air Quality and Meteorology Study (BAQS-Met) was an intensive, collaborative field campaign during the summer of 2007 that investigated the effects of transboundary pollution, local pollution, and local meteorology on air quality in southwestern Ontario. This analysis focuses on the measurements of the inorganic constituents of particulate matter with diameter of less than 1 ÎŒm (PM<sub>1</sub>), with a specific emphasis on nitrate. We evaluate the ability of AURAMS, Environment Canada's chemical transport model, to represent regional air pollution in SW Ontario by comparing modelled aerosol inorganic chemical composition with measurements from Aerosol Mass Spectrometers (AMS) onboard the National Research Council (NRC) of Canada Twin Otter aircraft and at a ground site in Harrow, ON. The agreement between modelled and measured <i>p</i>NO<sub>3</sub><sup>&minus;</sup> at the ground site (observed mean (M<sub>obs</sub>) = 0.50 ÎŒg m<sup>â3</sup>; modelled mean (M<sub>mod</sub>) = 0.58 ÎŒg m<sup>â3</sup>; root mean square error (RSME) = 1.27 ÎŒg m<sup>â3</sup>) was better than aloft (M<sub>obs</sub> = 0.32 ÎŒg m<sup>â3</sup>; M<sub>mod</sub> = 0.09 ÎŒg m<sup>â3</sup>; RSME = 0.48 ÎŒg m<sup>â3</sup>). Possible reasons for discrepancies include errors in (i) emission inventories, (ii) atmospheric chemistry, (iii) predicted meteorological parameters, or (iv) gas/particle thermodynamics in the model framework. Using the inorganic thermodynamics model, ISORROPIA, in an offline mode, we find that the assumption of thermodynamic equilibrium is consistent with observations of gas and particle composition at Harrow. We develop a framework to assess the sensitivity of PM<sub>1</sub> nitrate to meteorological and chemical parameters and find that errors in both the predictions of relative humidity and free ammonia (FA ⥠NH<sub>3</sub><sub>(g)</sub> + <i>p</i>NH<sub>4</sub><sup>+</sup> â 2 · <i>p</i>SO<sub>4</sub><sup>2-</sup>) are responsible for the poor agreement between modelled and measured values
Diversification and agrarian change under environmental constraints in rural China: Evidence from a poor township of Beijing municipality
Working paper du GATE 2007-11This article illustrates the impact of changes related to market reforms and environmental policies on the economic structure in rural China by providing a comparative analysis of several villages in a poor township in Beijing municipality. Two main concomitant phenomena are affecting agricultural and non-agricultural choices in the studied area. First, the introduction of market mechanisms is encouraging local population to engage in new activities that are closer to local comparative advantages. Second, rural households are facing new constraints in the form of environmental protection measures, which have weakened traditional insurance channels provided by forest resources and cattle stock. Drawing on household-level survey data and interviews with village heads conducted in ten villages of Labagoumen township in December 2003, this article analyzes households decisions in response to market reforms and environmental constraints. We find large disparities both between villages and households in the diversification process and discuss the reasons of observed inertia in the region, most households still heavily relying on corn production
Sensitivity Parameter and Time Variations of Fundamental Constants
The sensitivity parameter is widely used for quantifying fine tuning.
However, examples show it fails to give correct results under certain
circumstances. We argue that the problems of the sensitivity parameter are
almost identical to the consequences we have to solved if the time-varying fine
structure constant is proved to be true. The high sensitivity of the energy
scale parameter (\Lambda) to the dimensionless coupling constant plays an
important role in these problems. It affects the reliability of the sensitivity
parameter via mechanisms such as dynamical symmetry breaking, chiral symmetry
breaking etc. The reliability of the sensitivity parameter can be improved if
it is used properly.Comment: 6 page
The Las Campanas IR Survey: Early Type Galaxy Progenitors Beyond Redshift One
(Abridged) We have identified a population of faint red galaxies from a 0.62
square degree region of the Las Campanas Infrared Survey whose properties are
consistent with their being the progenitors of early-type galaxies. The optical
and IR colors, number-magnitude relation and angular clustering together
indicate modest evolution and increased star formation rates among the
early-type field population at redshifts between one and two. The counts of red
galaxies with magnitudes between 17 and 20 rise with a slope that is much
steeper than that of the total H sample. The surface density of red galaxies
drops from roughly 3000 per square degree at H = 20.5, I-H > 3 to ~ 20 per
square degree at H = 20, I-H > 5. The V-I colors are approximately 1.5
magnitudes bluer on average than a pure old population and span a range of more
than three magnitudes. The colors, and photometric redshifts derived from them,
indicate that the red galaxies have redshift distributions adequately described
by Gaussians with sigma_z ~ 0.2V-I3$ are primarily in the 1.5 < z < 2
range. We find co-moving correlation lengths of 9-10 Mpc at z ~ 1, comparable
to, or larger than, those found for early-type galaxies at lower redshifts. A
simple photometric evolution model reproduces the counts of the red galaxies,
with only a ~ 30% decline in the underlying space density of early-type
galaxies at z ~ 1.2. We suggest on the basis of the colors, counts, and
clustering that these red galaxies are the bulk of the progenitors of present
day early-type galaxies.Comment: 5 pages, 3 figures, accepted for publication in the ApJ Letter
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