488 research outputs found
An equivalence between inverse sumset theorems and inverse conjectures for the U^3 norm
We establish a correspondence between inverse sumset theorems (which can be
viewed as classifications of approximate (abelian) groups) and inverse theorems
for the Gowers norms (which can be viewed as classifications of approximate
polynomials). In particular, we show that the inverse sumset theorems of
Freiman type are equivalent to the known inverse results for the Gowers U^3
norms, and moreover that the conjectured polynomial strengthening of the former
is also equivalent to the polynomial strengthening of the latter. We establish
this equivalence in two model settings, namely that of the finite field vector
spaces F_2^n, and of the cyclic groups Z/NZ.
In both cases the argument involves clarifying the structure of certain types
of approximate homomorphism.Comment: 23 page
Avalanche Predictions Based on ML
Our Avalanche Prediction Model utilizes machine learning to analyze weather and climate data in order to provide users in the Northern California back-country with accurate probabilities of avalanche occurrences. Snow forecasts only provide information relating to how much snow will fall. Current avalanche danger ratings only provide the potential level for injury there is if an avalanche will occur. Our system, Avy Safe ML, let’s users survey geographic terrain and see direct probability indicators for precise geo-locations of mountain faces and ranges. These indicators are represented as variably-shaded geo-polygons that indicate avalanche risk classifications. Our data visualization allows access to the results of calculations accomplished by our support vector machine model all in a user-friendly experience. Avy Safe ML hopes to provide back-country folks with the ability ”know before they go” into potentially dangerous terrain
How well do health professionals interpret diagnostic information? A systematic review.
Published onlineResearch Support, Non-U.S. Gov'tOBJECTIVE: To evaluate whether clinicians differ in how they evaluate and interpret diagnostic test information. DESIGN: Systematic review. DATA SOURCES: MEDLINE, EMBASE and PsycINFO from inception to September 2013; bibliographies of retrieved studies, experts and citation search of key included studies. ELIGIBILITY CRITERIA FOR SELECTING STUDIES: Primary studies that provided information on the accuracy of any diagnostic test (eg, sensitivity, specificity, likelihood ratios) to health professionals and that reported outcomes relating to their understanding of information on or implications of test accuracy. RESULTS: We included 24 studies. 6 assessed ability to define accuracy metrics: health professionals were less likely to identify the correct definition of likelihood ratios than of sensitivity and specificity. -25 studies assessed Bayesian reasoning. Most assessed the influence of a positive test result on the probability of disease: they generally found health professionals' estimation of post-test probability to be poor, with a tendency to overestimation. 3 studies found that approaches based on likelihood ratios resulted in more accurate estimates of post-test probability than approaches based on estimates of sensitivity and specificity alone, while 3 found less accurate estimates. 5 studies found that presenting natural frequencies rather than probabilities improved post-test probability estimation and speed of calculations. CONCLUSIONS: Commonly used measures of test accuracy are poorly understood by health professionals. Reporting test accuracy using natural frequencies and visual aids may facilitate improved understanding and better estimation of the post-test probability of disease.This work was partially funded by the UK Medical Research Council
(Grant Code G0801405)
Metaphors of Identity: Focus Groups
This set of files contain focus groups data collected for the first phase of the Metaphors of Identity research project. Focus groups involved a small group of people (3 to 6 participants) across different age groups: teenagers (15-17 age group), young adults (19-29 age group) and an older age group (50-60 age group). Focus groups took place between the period March 2012 and March 2013. Each group engaged in a metaphoric discussion that largely arose from a projective technique involving themes pertaining to different levels of abstraction and then subjected to the phenomenological process of 'eidetic' reduction. A visual representation of the metaphor was produced by the participants
How well do health professionals interpret diagnostic information?:A systematic review
OBJECTIVE: To evaluate whether clinicians differ in how they evaluate and interpret diagnostic test information. DESIGN: Systematic review. DATA SOURCES: MEDLINE, EMBASE and PsycINFO from inception to September 2013; bibliographies of retrieved studies, experts and citation search of key included studies. ELIGIBILITY CRITERIA FOR SELECTING STUDIES: Primary studies that provided information on the accuracy of any diagnostic test (eg, sensitivity, specificity, likelihood ratios) to health professionals and that reported outcomes relating to their understanding of information on or implications of test accuracy. RESULTS: We included 24 studies. 6 assessed ability to define accuracy metrics: health professionals were less likely to identify the correct definition of likelihood ratios than of sensitivity and specificity. –25 studies assessed Bayesian reasoning. Most assessed the influence of a positive test result on the probability of disease: they generally found health professionals’ estimation of post-test probability to be poor, with a tendency to overestimation. 3 studies found that approaches based on likelihood ratios resulted in more accurate estimates of post-test probability than approaches based on estimates of sensitivity and specificity alone, while 3 found less accurate estimates. 5 studies found that presenting natural frequencies rather than probabilities improved post-test probability estimation and speed of calculations. CONCLUSIONS: Commonly used measures of test accuracy are poorly understood by health professionals. Reporting test accuracy using natural frequencies and visual aids may facilitate improved understanding and better estimation of the post-test probability of disease
Places of joy : the role of heritage after lockdown
[Abstract not available
Crystal constructions in Number Theory
Weyl group multiple Dirichlet series and metaplectic Whittaker functions can
be described in terms of crystal graphs. We present crystals as parameterized
by Littelmann patterns and we give a survey of purely combinatorial
constructions of prime power coefficients of Weyl group multiple Dirichlet
series and metaplectic Whittaker functions using the language of crystal
graphs. We explore how the branching structure of crystals manifests in these
constructions, and how it allows access to some intricate objects in number
theory and related open questions using tools of algebraic combinatorics
Heritage sites, value and wellbeing : learning from the COVID-19 pandemic in England
The COVID-19 lockdown of society in 2020 deprived people of access to many heritage sites. This made the public uniquely aware of why they visited heritage sites and what they valued about the visits, once heritage sites reopened. In particular, regaining access framed visits in terms of personal agency and wellbeing. Notions of capability, social connections, ontological security, and trust–all important elements of wellbeing–were widely shared values. Heritage sites also offered distinct opportunities for combining hedonic (subjective) and eudaimonic (psychological) wellbeing effects. While heritage value cannot be reduced to wellbeing effects, we suggest that constructive awareness of how these effects may be generated can enhance the outcome of visits to heritage sites
Shot noise in mesoscopic systems
This is a review of shot noise, the time-dependent fluctuations in the
electrical current due to the discreteness of the electron charge, in small
conductors. The shot-noise power can be smaller than that of a Poisson process
as a result of correlations in the electron transmission imposed by the Pauli
principle. This suppression takes on simple universal values in a symmetric
double-barrier junction (suppression factor 1/2), a disordered metal (factor
1/3), and a chaotic cavity (factor 1/4). Loss of phase coherence has no effect
on this shot-noise suppression, while thermalization of the electrons due to
electron-electron scattering increases the shot noise slightly. Sub-Poissonian
shot noise has been observed experimentally. So far unobserved phenomena
involve the interplay of shot noise with the Aharonov-Bohm effect, Andreev
reflection, and the fractional quantum Hall effect.Comment: 37 pages, Latex, 10 figures (eps). To be published in "Mesoscopic
Electron Transport," edited by L. P. Kouwenhoven, G. Schoen, and L. L. Sohn,
NATO ASI Series E (Kluwer Academic Publishing, Dordrecht
- …