Relevance thresholds in system evaluations

We introduce and explore the concept of an individual's relevance threshold as a way of reconciling differences in outcomes between batch and user experiments

Single atom edge-like states via quantum interference

We demonstrate how quantum interference may lead to the appearance of robust edge-like states of a single ultracold atom in a two-dimensional optical ribbon. We show that these states can be engineered either within the manifold of local ground states of the sites forming the ribbon, or of states carrying one unit of angular momentum. In the former case, we show that the implementation of edge-like states can be extended to other geometries, such as tilted square lattices. In the latter case, we suggest to use the winding number associated to the angular momentum as a synthetic dimension.Comment: 5 pages, 5 figure

User performance versus precision measures for simple search tasks

Several recent studies have demonstrated that the type of improvements in information retrieval system effectiveness reported in forums such as SIGIR and TREC do not translate into a benefit for users. Two of the studies used an instance recall task, and a third used a question answering task, so perhaps it is unsurprising that the precision based measures of IR system effectiveness on one-shot query evaluation do not correlate with user performance on these tasks. In this study, we evaluate two different information retrieval tasks on TREC Web-track data: a precision-based user task, measured by the length of time that users need to find a single document that is relevant to a TREC topic; and, a simple recall-based task, represented by the total number of relevant documents that users can identify within five minutes. Users employ search engines with controlled mean average precision (MAP) of between 55% and 95%. Our results show that there is no significant relationship between system effectiveness measured by MAP and the precision-based task. A significant, but weak relationship is present for the precision at one document returned metric. A weak relationship is present between MAP and the simple recall-based task

Wave-vector and polarization dependence of conical refraction

We experimentally address the wave-vector and polarization dependence of the internal conical refraction phenomenon by demonstrating that an input light beam of elliptical transverse profile refracts into two beams after passing along one of the optic axes of a biaxial crystal, i.e. it exhibits double refraction instead of refracting conically. Such double refraction is investigated by the independent rotation of a linear polarizer and a cylindrical lens. Expressions to describe the position and the intensity pattern of the refracted beams are presented and applied to predict the intensity pattern for an axicon beam propagating along the optic axis of a biaxial crystal

Polarization tailored novel vector beams based on conical refraction

Coherent vector beams with involved states of polarization (SOP) are widespread in the literature, having applications in laser processing, super-resolution imaging and particle trapping. We report novel vector beams obtained by transforming a Gaussian beam passing through a biaxial crystal, by means of the conical refraction phenomenon. We analyze both experimentally and theoretically the SOP of the different vector beams generated and demonstrate that the SOP of the input beam can be used to control both the shape and the SOP of the transformed beam. We also identify polarization singularities of such beams for the first time and demonstrate their control by the SOP of an input beam

Optical vault: reconfigurable bottle beam by conically refracted light

We employ conical refraction of light in a biaxial crystal to create an optical bottle for trapping and manipulation of particles. We show that by just varying the polarization of the input light the bottle can be opened and closed at will. We experimentally demonstrate stable photophoretic trapping and controllable loading and unloading of light absorbing particles in the trap.Comment: 4 pages, 5 figure

Retesting visual fields: Utilizing prior information to decrease test-retest variability in glaucoma

PURPOSE. To determine whether sensitivity estimates from an individual's previous visual field tests can be incorporated into perimetric procedures to improve accuracy and reduce test-retest variability at subsequent visits. METHODS. Computer simulation was used to determine the error, distribution of errors and presentation count for a series of perimetric algorithms. Baseline procedures were Full Threshold and Zippy Estimation by Sequential Testing (ZEST). Retest strategies were (1) allowing ZEST to continue from the previous test without reinitializing the probability density function [pdf], (2) running ZEST with a Gaussian pdf centered about the previous result; (3) retest minimizing uncertainty (REMU), a new procedure combining suprathreshold and ZEST procedures incorporating prior test information. Empiric visual field data of 265 control and 163 patients with glaucoma were input into the simulation. Four error conditions were modeled: patients who make no errors, 15% false-positive (FP) with 3% false-negative (FN) errors, 15% FN with 3% FP errors, and 20% FP with 20% FN errors. RESULTS. If sensitivity was stable from test to retest, an the retest algorithms were faster than the baseline algorithms by, on average, one presentation per location and are significantly more accurate (P < 0.05). When visual fields changed from test to retest, REMU was faster and more accurate than the other retest approaches and the baseline procedures. Relative to the baseline procedures, REMU showed decreased test-retest variability in impaired regions of Visual field. CONCLUSIONS. The obvious approaches to retest, such as continuing the previous procedure or seeding with previous values, have limitations when sensitivity changes between tests. REMU, however, significantly improves both accuracy and precision of testing and displays minimal bias, even when fields change and patients make errors