7,274 research outputs found
Explaining Violation Traces with Finite State Natural Language Generation Models
An essential element of any verification technique is that of identifying and
communicating to the user, system behaviour which leads to a deviation from the
expected behaviour. Such behaviours are typically made available as long traces
of system actions which would benefit from a natural language explanation of
the trace and especially in the context of business logic level specifications.
In this paper we present a natural language generation model which can be used
to explain such traces. A key idea is that the explanation language is a CNL
that is, formally speaking, regular language susceptible transformations that
can be expressed with finite state machinery. At the same time it admits
various forms of abstraction and simplification which contribute to the
naturalness of explanations that are communicated to the user
Guiding of Rydberg atoms in a high-gradient magnetic guide
We study the guiding of Rb 59D Rydberg atoms in a linear,
high-gradient, two-wire magnetic guide. Time delayed microwave ionization and
ion detection are used to probe the Rydberg atom motion. We observe guiding of
Rydberg atoms over a period of 5 ms following excitation. The decay time of the
guided atom signal is about five times that of the initial state. We attribute
the lifetime increase to an initial phase of -changing collisions and
thermally induced Rydberg-Rydberg transitions. Detailed simulations of Rydberg
atom guiding reproduce most experimental observations and offer insight into
the internal-state evolution
Microscopic Theory of Spontaneous Decay in a Dielectric
The local field correction to the spontanous dacay rate of an impurity source
atom imbedded in a disordered dielectric is calculated to second order in the
dielectric density. The result is found to differ from predictions associated
with both "virtual" and "real" cavity models of this decay process. However, if
the contributions from two dielectric atoms at the same position are included,
the virtual cavity result is reproduced.Comment: 12 Page
Scale-invariant large nonlocality in polycrystalline graphene
The observation of large nonlocal resistances near the Dirac point in
graphene has been related to a variety of intrinsic Hall effects, where the
spin or valley degrees of freedom are controlled by symmetry breaking
mechanisms. Engineering strong spin or valley Hall signals on scalable graphene
devices could stimulate further practical developments of spin- and
valleytronics. Here we report on scale-invariant nonlocal transport in
large-scale chemical vapour deposition graphene under an applied external
magnetic field. Contrary to previously reported Zeeman spin Hall effect, our
results are explained by field-induced spin-filtered edge states whose
sensitivity to grain boundaries manifests in the nonlocal resistance. This
phenomenon, related to the emergence of the quantum Hall regime, persists up to
the millimeter scale, showing that polycrystalline morphology can be imprinted
in nonlocal transport. This suggests that topological Hall effects in
large-scale graphene materials are highly sensitive to the underlying
structural morphology, limiting practical realizations.Comment: Main paper (14 pages, 5 figures) and Supplementary information (8
pages, 8 figures
Stream Network Geometry and the Spatial Influence of Aquatic Insect Subsidies Across the Contiguous United States
Emergent aquatic insects transport aquatic‐derived resources into terrestrial ecosystems but are rarely studied at landscape or regional scales. Here, we investigate how stream network geometry constrains the spatial influence of aquatic insect subsidies in terrestrial ecosystems. We also explore potential factors (i.e., climate, topography, soils, and vegetation) that could produce variation in stream network geometry and thus change the extent of aquatic insect subsidies from one region to another. The stream signature is the percentage of aquatic insect subsidies traveling a given distance into the terrestrial ecosystem, relative to what comes out of the stream. We use this concept to model the spatial extent (area) and distribution (spatial patterning) of aquatic subsidies in terrestrial ecosystems across the contiguous United States. Our findings suggest that at least 8% of the subsidies measured at the aquatic–terrestrial boundary (i.e., the 8% stream signature) are typically transferred throughout the entire watershed and that variation in this spatial extent is largely influenced by the drainage density of the stream network. Moreover, we found stream signatures from individual stream reaches overlap such that the spatial extent of the 8% stream signature often includes inputs from multiple stream reaches. Landscape‐scale stream network characteristics increased the area of overlapping stream signatures more than reach‐scale channel properties. Finally, we found runoff was an important factor influencing stream network geometry suggesting a potential effect of climate on aquatic‐to‐terrestrial linkages that have been understudied.Financial support was provided by a grant from this National Science Foundation (EF‐1802872) to DCA, and the Adams Family Endowment at the University of Oklahoma provided additional financial support to DAK. Open Access fees paid for in whole or in part by the University of Oklahoma Libraries.Ye
Self-consistent massive disks in triaxial dark matter halos
Galactic disks in triaxial dark matter halos become deformed by the
elliptical potential in the plane of the disk in such a way as to counteract
the halo ellipticity. We develop a technique to calculate the equilibrium
configuration of such a disk in the combined disk-halo potential, which is
based on the method of Jog (2000) but accounts for the radial variation in both
the halo potential and the disk ellipticity. This crucial ingredient results in
qualitatively different behavior of the disk: the disk circularizes the
potential at small radii, even for a reasonably low disk mass. This effect has
important implications for proposals to reconcile cuspy halo density profiles
with low surface brightness galaxy rotation curves using halo triaxiality. The
disk ellipticities in our models are consistent with observational estimates
based on two-dimensional velocity fields and isophotal axis ratios.Comment: ApJ, in pres
Patient-reported outcomes following flexible sigmoidoscopy screening for colorectal cancer in a demonstration screening programme in the UK
<p>OBJECTIVES: Flexible sigmoidoscopy (FS) screening for colorectal cancer will be introduced into the National Cancer Screening Programmes in England in 2013. Patient-reported outcome measures (PROMs) from trial participants indicate high acceptability and no adverse physical or psychological consequences, but this may not generalize to routine screening in the community. This study examined PROMs in a community-based FS screening programme.</p>
<p>METHODS: Eligible adults aged 58-59 (n = 2016) registered at 34 London general practices were mailed a National Health Service-endorsed invitation to attend FS screening. Pain and side-effects were assessed in a 'morning-after' questionnaire, and satisfaction was assessed in a three-month follow-up questionnaire. Anxiety, self-rated health and colorectal symptoms were assessed at prescreening and follow-up.</p>
<p>RESULTS: In total, 1020 people attended screening and were included in the current analyses, of whom 913 (90%) returned the morning-after questionnaire, and 674 (66%) the follow-up questionnaire. The prescreening questionnaire had been completed by 751 (74%) of those who attended. The majority (87%) of respondents reported no pain or mild pain, and the most frequent side-effect (wind) was only experienced more than mildly by 16%. Satisfaction was extremely high, with 98% glad they had the test; 97% would encourage a friend to have it. From prescreening to follow-up there were no changes in anxiety or self-rated health, and the number of colorectal symptoms declined. Satisfaction and changes in wellbeing were not moderated by gender, deprivation, ethnicity or screening outcome.</p>
<p>CONCLUSIONS: PROMs indicate high acceptability of FS screening in 58-59 year olds, with no adverse effects on colorectal symptoms, health status or psychological wellbeing.</p>
The representativeness of the dental calculus dietary record: Insights from Taï chimpanzee faecal phytoliths
A molecular theory for two-photon and three-photon fluorescence polarization
In the analysis of molecular structure and local order in heterogeneous samples, multiphoton excitation of fluorescence affords chemically specific information and high-resolution imaging. This report presents the results of an investigation that secures a detailed theoretical representation of the fluorescence polarization produced by one-, two-, and three-photon excitations, with orientational averaging procedures being deployed to deliver the fully disordered limits. The equations determining multiphoton fluorescence response prove to be expressible in a relatively simple, generic form, and graphs exhibit the functional form of the multiphoton fluorescence polarization. Amongst other features, the results lead to the identification of a condition under which the fluorescence produced through the concerted absorption of any number of photons becomes completely unpolarized. It is also shown that the angular variation of fluorescence intensities is reliable indicator of orientational disorder
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