2,732 research outputs found
Critical sets of the total variance of state detect all SLOCC entanglement classes
We present a general algorithm for finding all classes of pure multiparticle
states equivalent under Stochastic Local Operations and Classsical
Communication (SLOCC). We parametrize all SLOCC classes by the critical sets of
the total variance function. Our method works for arbitrary systems of
distinguishable and indistinguishable particles. We also discuss the Morse
indices of critical points which have the interpretation of the number of
independent non-local perturbations increasing the variance and hence
entanglement of a state. We illustrate our method by two examples.Comment: 4 page
Surface contamination of cars : a review
This review surveys the problem of surface contamination for cars, which poses a growing engineering challenge to vehicle manufacturers, operators and users. Both driversâ vision and vehicle visibility need to be maintained under a wide range of environmental conditions. This requires managing the flow of surface water on wind screens and side glazing. The rate of deposition of solid contaminants on glazing, lights, license plates and external mirrors also needs to be minimised. Maintaining vehicle aesthetics and limiting the transfer of contaminants to the hands and clothes of users from soiled surfaces are also significant issues. Recently, keeping camera lenses clean has emerged as a key concern, as these systems transition from occasional manoeuvring aids to sensors for safety systems. The deposition of water and solid contaminants onto car surfaces is strongly influenced by unsteady vehicle aerodynamic effects. Airborne water droplets falling as rain or lifted as spray by tyres interact with wakes, vortices and shear flows and accumulate on vehicle surfaces as a consequence. The same aerodynamic effects also control the movement of surface water droplets, rivulets and films; hence, particular attention is paid to surface water management over the front side-glass and the deposition of contaminants on the rear surfaces. The test methods used in the automotive industry are reviewed, as are numerical simulation techniques
Assessing Human Error Against a Benchmark of Perfection
An increasing number of domains are providing us with detailed trace data on
human decisions in settings where we can evaluate the quality of these
decisions via an algorithm. Motivated by this development, an emerging line of
work has begun to consider whether we can characterize and predict the kinds of
decisions where people are likely to make errors.
To investigate what a general framework for human error prediction might look
like, we focus on a model system with a rich history in the behavioral
sciences: the decisions made by chess players as they select moves in a game.
We carry out our analysis at a large scale, employing datasets with several
million recorded games, and using chess tablebases to acquire a form of ground
truth for a subset of chess positions that have been completely solved by
computers but remain challenging even for the best players in the world.
We organize our analysis around three categories of features that we argue
are present in most settings where the analysis of human error is applicable:
the skill of the decision-maker, the time available to make the decision, and
the inherent difficulty of the decision. We identify rich structure in all
three of these categories of features, and find strong evidence that in our
domain, features describing the inherent difficulty of an instance are
significantly more powerful than features based on skill or time.Comment: KDD 2016; 10 page
Identifying different typologies of experiences and coping strategies in men with rheumatoid arthritis: A Q-methodology study
Objective: To identify typologies of experiences and coping strategies of men with RA Design: Q-methodology (a qualitative and quantitative approach to grouping people according to their subjective opinion). Men with RA sorted 64 statements relating to their experience of living with RA according to level of agreement across a normal distribution grid. Data were examined using Q-factor analysis. Setting: Rheumatology outpatient departments in the UK Participants: 30 of 65 invited men with RA participated in this study (46%) Results: All participants ranked highly the need to be well informed about their medication and the importance of keeping a positive attitude. Two factors describing the experiences and coping strategies of male patients living with RA were identified: Factor A: âAcknowledge, accept and adaptâ (n=14) take a pro-active approach to managing the impact of RA and find different ways of doing things; whilst Factor B: âTrying to match up to a macho idealâ (n=8) are determined to continue with their pre-RA lives, and therefore push themselves to carry on even if this causes them pain. They are frustrated and angry due to the impact of RA but they internalise this rather than directing it at others. Conclusion: Whilst some men adapt to their RA by renegotiating their masculine identity, others struggle to relinquish their traditional masculine roles. Further research is needed to identify whether the finding that there are two distinct groups of men with RA can be generalised, and if so whether the differences can be explained by clinical, social or psychological factors, which may inform different therapeutic approaches
Error by design: Methods for predicting device usability
This paper introduces the idea of predicting âdesigner errorâ by evaluating devices using Human Error Identification (HEI) techniques. This is demonstrated using Systematic Human Error Reduction and Prediction Approach (SHERPA) and Task Analysis For Error Identification (TAFEI) to evaluate a vending machine. Appraisal criteria which rely upon user opinion, face validity and utilisation are questioned. Instead a quantitative approach, based upon signal detection theory, is recommended. The performance of people using SHERPA and TAFEI are compared with heuristic judgement and each other. The results of these studies show that both SHERPA and TAFEI are better at predicting errors than the heuristic technique. The performance of SHERPA and TAFEI are comparable, giving some confidence in the use of these approaches. It is suggested that using HEI techniques as part of the design and evaluation process could help to make devices easier to use
The 'CUB' Budget as a Measure of Fiscal Policy. Quarterly Economic Commentary Special Article, January 1976
In a recession or depression, as at present, government budgets tend
to be much less expansionary in their effects on the economy than one
might infer from the sizes of their overall deficits. In other words, those
who try to gauge the effect of the budget on demand in the economy by
reference .to the size of the deficit in the overall budget are likely, in a
recession, to be wrong.
When government budget deficits rise, the usual interpretation is
that the budget is more expansionary than theretofore in its influence
on the economy, and when budget deficits fall (or surpluses grow), the
usual interpretation is that the influence is less expansionary (or more
contractionary). But the fact is that increased deficits are not necessarily
more expansionary, nor are reduced deficits necessarily more contractionary,
even apart from such matters as the types of taxes used, the
mix of expenditures, the ways in which deficits are financed, and movements
in the supply of money. The sizes of budget deficits and surpluses
are influenced not only by the direction and strength of fiscal policy, but
by short-term movements of the economy itself
Integrable Unsteady Motion With an Application to Ocean Eddies
Application of the Brown-Samelson theorem, which shows that particle motion is integrable in a class of vorticity-conserving, two-dimensional incompressible hows, is extended here to a class of explicit time dependent dynamically balanced flows in multilayered systems. Particle motion for nonsteady two-dimensional flows with discontinuities in the vorticity or potential vorticity fields (modon solutions) is shown to be integrable. An example of a two-layer modon solution constrained by observations of a Gulf Stream ring system is discussed
Matrix String Theory and its Moduli Space
The correspondence between Matrix String Theory in the strong coupling limit
and IIA superstring theory can be shown by means of the instanton solutions of
the former. We construct the general instanton solutions of Matrix String
Theory which interpolate between given initial and final string configurations.
Each instanton is characterized by a Riemann surface of genus h with n
punctures, which is realized as a plane curve. We study the moduli space of
such plane curves and find out that, at finite N, it is a discretized version
of the moduli space of Riemann surfaces: instead of 3h-3+n its complex
dimensions are 2h-3+n, the remaining h dimensions being discrete. It turns out
that as tends to infinity, these discrete dimensions become continuous, and
one recovers the full moduli space of string interaction theory.Comment: 30 pages, LaTeX, JHEP.cls class file, minor correction
The role of double diffusive interleaving in mesoscale dynamics: An hypothesis
It is hypothesized that double diffusive interleaving can act to enhance the temperature, salinity and buoyancy signatures of some mesoscale structures. The hypothesis is founded on theoretical results showing that the fluxes produced by double diffusive interleaving can have counter-gradient components, and on the observations that isolated mesoscale rings have a long lifetime and that there is intense interleaving in the frontal zone typically surrounding the ring. Quantitative examples for a warm and a cold core ring demonstrate the feasibility of the hypothesis. Some suggestions are given for extending the hypothesis to include other mesoscale features. Also theoretical investigations and field experiments to test further the hypothesis are suggested
Surface Flow Structure of the Gulf Stream From Composite Imagery and Satellite-Tracked Drifters
A unique set of coutemporaneous satellite-tracked drifters and five-day composite Advanced Very High Resolution Radionmeter (AVHRR) satellite imagery of the North Atlantic has been analyzed to examine the surface flow structure of the Gulf Stream. The study region was divided into two sections, greater than 37 degrees N and less than 37 degrees N, in order to answer the question of geographic variability. Fractal and spectral analyses methods were applied to the data. Fractal analysis of the Lagrangian trajectories showed a fractal dimension of 1.21 +/- 0.02 with a scaling range of 83 - 343 km. The fractal dimension of the temperature fronts of the composite imagery is similar for the two regions with D = 1.11 +/- 0.01 over a scaling range of 4 - 44 km. Spectral analysis also reports a fairly consistent value for the spectral slope and its scaling range. Therefore, we conclude there is no geographic variability in the data set. A suitable scaling range for this contemporaneous data set is 80 - 200 km which is consistent with the expected physical conditions in the region. Finally, we address the idea of using five-day composite imagery to infer the surface flow of the Gulf Stream. Close analyses of the composite thermal fronts and the Lagrangian drifter trajectories show that the former is not a good indicator of the latter
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