5,080 research outputs found
Application of computer-aided dispatch in law enforcement: An introductory planning guide
A set of planning guidelines for the application of computer-aided dispatching (CAD) to law enforcement is presented. Some essential characteristics and applications of CAD are outlined; the results of a survey of systems in the operational or planning phases are summarized. Requirements analysis, system concept design, implementation planning, and performance and cost modeling are described and demonstrated with numerous examples. Detailed descriptions of typical law enforcement CAD systems, and a list of vendor sources, are given in appendixes
Bringing Salary Transparency to the World: Computing Robust Compensation Insights via LinkedIn Salary
The recently launched LinkedIn Salary product has been designed with the goal
of providing compensation insights to the world's professionals and thereby
helping them optimize their earning potential. We describe the overall design
and architecture of the statistical modeling system underlying this product. We
focus on the unique data mining challenges while designing and implementing the
system, and describe the modeling components such as Bayesian hierarchical
smoothing that help to compute and present robust compensation insights to
users. We report on extensive evaluation with nearly one year of de-identified
compensation data collected from over one million LinkedIn users, thereby
demonstrating the efficacy of the statistical models. We also highlight the
lessons learned through the deployment of our system at LinkedIn.Comment: Conference information: ACM International Conference on Information
and Knowledge Management (CIKM 2017
A cohort study of influences, health outcomes and costs of patients' health-seeking behaviour for minor ailments from primary and emergency care settings
To compare health-related and cost-related outcomes of consultations for symptoms suggestive of minor ailments in emergency departments (EDs), general practices and community pharmacies
When are active Brownian particles and run-and-tumble particles equivalent? Consequences for motility-induced phase separation
Active Brownian particles (ABPs, such as self-phoretic colloids) swim at
fixed speed along a body-axis that rotates by slow angular
diffusion. Run-and-tumble particles (RTPs, such as motile bacteria) swim with
constant \u until a random tumble event suddenly decorrelates the
orientation. We show that when the motility parameters depend on density
but not on , the coarse-grained fluctuating hydrodynamics of
interacting ABPs and RTPs can be mapped onto each other and are thus strictly
equivalent. In both cases, a steeply enough decreasing causes phase
separation in dimensions , even when no attractive forces act between
the particles. This points to a generic role for motility-induced phase
separation in active matter. However, we show that the ABP/RTP equivalence does
not automatically extend to the more general case of \u-dependent motilities
How important is randomisation in a stepped wedge trial?
In cluster randomised trials, randomisation increases internal study validity. If enough clusters are randomised, an unadjusted analysis should be unbiased. If a smaller number of clusters are included, stratified or matched randomisation can increase comparability between trial arms. In addition, an adjusted analysis may be required; nevertheless, randomisation removes the possibility for systematically biased allocation and increases transparency. In stepped wedge trials, clusters are randomised to receive an intervention at different start times ('steps'), and all clusters eventually receive it. In a recent study protocol for a 'modified stepped wedge trial', the investigators considered randomisation of the clusters (hospital wards), but decided against it for ethical and logistical reasons, and under the assumption that it would not add much to the rigour of the evaluation. We show that the benefits of randomisation for cluster randomised trials also apply to stepped wedge trials. The biggest additional issue for stepped wedge trials in relation to parallel cluster randomised trials is the need to control for secular trends in the outcome. Analysis of stepped wedge trials can in theory be based on 'horizontal' or 'vertical' comparisons. Horizontal comparisons are based on measurements taken before and after the intervention is introduced in each cluster, and are unbiased if there are no secular trends. Vertical comparisons are based on outcome measurements from clusters that have switched to the intervention condition and those from clusters that have yet to switch, and are unbiased under randomisation since at any time point, which clusters are in intervention and control conditions will have been determined at random. Secular outcome trends are a possibility in many settings. Many stepped wedge trials are analysed with a mixed model, including a random effect for cluster and fixed effects for time period to account for secular trends, thereby combining both vertical and horizontal comparisons of intervention and control clusters. The importance of randomisation in a stepped wedge trial is that the effects of time can be estimated from the data, and bias from secular trends that would otherwise arise can be controlled for, provided the trends are correctly specified in the model
Yield stress, heterogeneities and activated processes in soft glassy materials
The rheological behavior of soft glassy materials basically results from the
interplay between shearing forces and an intrinsic slow dynamics. This
competition can be described by a microscopic theory, which can be viewed as a
nonequilibrium schematic mode-coupling theory. This statistical mechanics
approach to rheology results in a series of detailed theoretical predictions,
some of which still awaiting for their experimental verification. We present
new, preliminary, results about the description of yield stress, flow
heterogeneities and activated processes within this theoretical framework.Comment: Paper presented at "III Workshop on Non Equilibrium Phenomena...",
Pisa 22-27 Sep. 200
Modelling fish habitat preference with a genetic algorithm-optimized Takagi-Sugeno model based on pairwise comparisons
Species-environment relationships are used for evaluating the current status of target species and the potential impact of natural or anthropogenic changes of their habitat. Recent researches reported that the results are strongly affected by the quality of a data set used. The present study attempted to apply pairwise comparisons to modelling fish habitat preference with Takagi-Sugeno-type fuzzy habitat preference models (FHPMs) optimized by a genetic algorithm (GA). The model was compared with the result obtained from the FHPM optimized based on mean squared error (MSE). Three independent data sets were used for training and testing of these models. The FHPMs based on pairwise comparison produced variable habitat preference curves from 20 different initial conditions in the GA. This could be partially ascribed to the optimization process and the regulations assigned. This case study demonstrates applicability and limitations of pairwise comparison-based optimization in an FHPM. Future research should focus on a more flexible learning process to make a good use of the advantages of pairwise comparisons
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Joint retrievals of cloud and drizzle in marine boundary layer clouds using ground-based radar, lidar and zenith radiances
Active remote sensing of marine boundary-layer clouds is challenging as drizzle drops often dominate the observed radar reflectivity. We present a new method to simultaneously retrieve cloud and drizzle vertical profiles in drizzling boundary-layer clouds using surface-based observations of radar reflectivity, lidar attenuated backscatter, and zenith radiances under conditions when precipitation does not reach the surface. Specifically, the vertical structure of droplet size and water content of both cloud and drizzle is characterised throughout the cloud. An ensemble optimal estimation approach provides full error statistics given the uncertainty in the observations. To evaluate the new method, we first perform retrievals using synthetic measurements from large-eddy simulation snapshots of cumulus under stratocumulus, where cloud water path is retrieved with an error of 31 g m−2 . The method also performs well in non-drizzling clouds where no assumption of the cloud profile is required. We then apply the method to observations of marine stratocumulus obtained during the Atmospheric Radiation Measurement MAGIC deployment in the Northeast Pacific. Here, retrieved cloud water path agrees well with independent three-channel microwave radiometer retrievals, with a root mean square difference of 10–20 g m−2
Symmetry breaking in crossed magnetic and electric fields
We present the first observations of cylindrical symmetry breaking in highly
excited diamagnetic hydrogen with a small crossed electric field, and we give a
semiclassical interpretation of this effect. As the small perpendicular
electric field is added, the recurrence strengths of closed orbits decrease
smoothly to a minimum, and revive again. This phenomenon, caused by
interference among the electron waves that return to the nucleus, can be
computed from the azimuthal dependence of the classical closed orbits.Comment: 4 page REVTeX file including 5 postscript files (using psfig)
Accepted for publication in Physical Review Letters. Difference from earlier
preprint: we have discovered the cause of the earlier apparent discrepancy
between experiment and theory and now achieve excellent agreemen
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