Selective amplification of scars in a chaotic optical fiber

In this letter we propose an original mechanism to select scar modes through coherent gain amplification in a multimode D-shaped fiber. More precisely, we numerically demonstrate how scar modes can be amplified by positioning a gain region in the vicinity of specific points of a short periodic orbit known to give rise to scar modes

Ultrahigh harmonics from laser-assisted ion-atom collisions

We present a theoretical analysis of high-order harmonic generation from ion-atom collisions in the presence of linearly polarized intense laser pulses. Photons with frequencies significantly higher than in standard atomic high-harmonic generation are emitted. These harmonics are due to two different mechanisms: (i) collisional electron capture and subsequent laser-driven transfer of an electron between projectile and target atom; (ii) reflection of a laser-driven electron from the projectile leading to recombination at the parent atom.Comment: 5 pages, 4 figure

Archeological Investigations for the FM 270 Shared Use Path from Henderson Avenue to South of the HL&P Hot Water Canal, Harris and Galveston Counties, Texas

In June of 2014, AmaTerra Environmental, Inc. (AmaTerra) carried out an intensive archeological investigation of the Texas Department of Transportation’s proposed bicycle and pedestrian shared use path along Farm-to-Market (FM) 270 in Harris and Galveston Counties, Texas (CSJ: 3312-01-008 and 3312-02-012). The proposed project extends from Henderson Avenue to approximately 1,000 feet south of the Houston Light & Power (HL&P) Hot Water Canal and entails the construction of a 16-foot wide shared use path, which includes two bridges: one over Clear Creek and a second bridge over the HL&P Hot Water Canal. The total project length is approximately 1.1 miles and will require approximately 0.54 acres of newly proposed Right-of-Way (ROW). AmaTerra conducted the archeological survey under Texas Antiquities Permit No. 6912. Archeological investigations involved a pedestrian survey, the excavation of 15 shovel tests, and the excavation of six backhoe scrapes across the Area of Potential Effects (APE). Three archeological sites, 41GV53, 41GV78, and 41GV152, were revisited during field investigations. Site 41GV53 is situated on a prominent knoll overlooking Clear Creek. The site, a Prehistoric shell midden, is bisected by FM 270 with site components present on both sides of the roadway and extending into the Clear Creek Nature Preserve. Site components were observed within shovel tests and backhoe scrapes placed at the outside edge of the existing ROW. AmaTerra recommends that intact deposits associated with Site 41GV53 at the edge of the ROW and on the Clear Creek Nature Preserve may be eligible for NRHP/SAL listing. However, within the actual footprint of construction (see Appendix), there is no evidence that artifacts, features, or deposits relating to Site 41GV53 are intact. Site 41GV78 has been completely destroyed through the construction of FM 270, and no further archeological investigations at this site locale are warranted at this time. Site 41GV152, an historic period site containing structural and domestic debris, is also bisected by FM 270 and likely extends into the Clear Creek Nature Preserve. Archeologists observed brick fragments, tabby-like mortar, hand blown glass shards, a plain porcelain sherd, and oyster shell within two shovel tests and backhoe scrapes 3 and 4. AmaTerra recommends that the overall NRHP/SAL eligibility of Site 41GV152 is still undetermined, but that within the FM 270 ROW, there are no archeological deposits that could contribute to eligibility. Based on the results of field investigations, no additional archeological investigations within the proposed APE are warranted at this time. No artifacts were collected during this survey

Improved Semiclassical Approximation for Bose-Einstein Condensates: Application to a BEC in an Optical Potential

We present semiclassical descriptions of Bose-Einstein condensates for configurations with spatial symmetry, e.g., cylindrical symmetry, and without any symmetry. The description of the cylindrical case is quasi-one-dimensional (Q1D), in the sense that one only needs to solve an effective 1D nonlinear Schrodinger equation, but the solution incorporates correct 3D aspects of the problem. The solution in classically allowed regions is matched onto that in classically forbidden regions by a connection formula that properly accounts for the nonlinear mean-field interaction. Special cases for vortex solutions are treated too. Comparisons of the Q1D solution with full 3D and Thomas-Fermi ones are presented.Comment: 14 pages, 5 figure

Observations on typing from 136 million keystrokes

We report on typing behaviour and performance of 168,000 volunteers in an online study. The large dataset allows detailed statistical analyses of keystroking patterns, linking them to typing performance. Besides reporting distributions and confirming some earlier findings, we report two new findings. First, letter pairs typed by different hands or fingers are more predictive of typing speed than, for example, letter repetitions. Second, rollover-typing, wherein the next key is pressed before the previous one is released, is surprisingly prevalent. Notwithstanding considerable variation in typing patterns, unsupervised clustering using normalised inter-key intervals reveals that most users can be divided into eight groups of typists that differ in performance, accuracy, hand and finger usage, and rollover. The code and dataset are released for scientific use

Classical and quantum decay of one dimensional finite wells with oscillating walls

To study the time decay laws (tdl) of quasibounded hamiltonian systems we have considered two finite potential wells with oscillating walls filled by non interacting particles. We show that the tdl can be qualitatively different for different movement of the oscillating wall at classical level according to the characteristic of trapped periodic orbits. However, the quantum dynamics do not show such differences.Comment: RevTeX, 15 pages, 14 PostScript figures, submitted to Phys. Rev.

Reality Check: Combining Survey and Market Data to Estimate the Importance of Product Attributes

Discrete choice models estimated using hypothetical choices made in a survey setting (i.e., choice experiments) are widely used to estimate the importance of product attributes in order to make product design and marketing mix decisions. Choice experiments allow the researcher to estimate preferences for product features that do not yet exist in the market. However, parameters estimated from experimental data often show marked inconsistencies with those inferred from the market, reducing their usefulness in forecasting and decision making. We propose an approach for combining choice-based conjoint data with individual-level purchase data to produce estimates that are more consistent with the market. Unlike prior approaches for calibrating conjoint models so that they correctly predict aggregate market shares for a “baseline” market, the proposed approach is designed to produce parameters that are more consistent with those that can be inferred from individual-level market data. The proposed method relies on a new general framework for combining two or more sources of individual-level choice data to estimate a hierarchical discrete choice model. Past approaches to combining choice data assume that the population mean for the parameters is the same across both data sets and require that data sets are sampled from the same population. In contrast, we incorporate in the model individual characteristic variables, and assert only that the mapping between individuals\u27 characteristics and their preferences is the same across the data sets. This allows the model to be applied even if the sample of individuals observed in each data set is not representative of the population as a whole, so long as appropriate product-use variables are collected that can explain the systematic deviations between them. The framework also explicitly incorporates a model for the individual characteristics, which allows us to use Bayesian missing-data techniques to handle the situation where each data set contains different demographic variables. This makes the method useful in practice for a wide range of existing market and conjoint data sets. We apply the method to a set of conjoint and market data for minivan choice and find that the proposed method predicts holdout market choices better than a model estimated from conjoint data alone or a model that does not include demographic variables

How do people type on mobile devices? Observations from a study with 37,000 volunteers

© 2019 Association for Computing Machinery. This paper presents a large-scale dataset on mobile text entry collected via a web-based transcription task performed by 37,370 volunteers. The average typing speed was 36.2 WPM with 2.3% uncorrected errors. The scale of the data enables powerful statistical analyses on the correlation between typing performance and various factors, such as demographics, finger usage, and use of intelligent text entry techniques. We report effects of age and finger usage on performance that correspond to previous studies. We also find evidence of relationships between performance and use of intelligent text entry techniques: auto-correct usage correlates positively with entry rates, whereas word prediction usage has a negative correlation. To aid further work on modeling, machine learning and design improvements in mobile text entry, we make the code and dataset openly available

Multi-filament structures in relativistic self-focusing

A simple model is derived to prove the multi-filament structure of relativistic self-focusing with ultra-intense lasers. Exact analytical solutions describing the transverse structure of waveguide channels with electron cavitation, for which both the relativistic and ponderomotive nonlinearities are taken into account, are presented.Comment: 21 pages, 12 figures, submitted to Physical Review