Stability of Monitoring Weak Changes in Multiply Scattering Media with Ambient Noise Correlation: Laboratory Experiments

Previous studies have shown that small changes can be monitored in a scattering medium by observing phase shifts in the coda. Passive monitoring of weak changes through ambient noise correlation has already been applied to seismology, acoustics and engineering. Usually, this is done under the assumption that a properly reconstructed Green function as well as stable background noise sources are necessary. In order to further develop this monitoring technique, a laboratory experiment was performed in the 2.5MHz range in a gel with scattering inclusions, comparing an active (pulse-echo) form of monitoring to a passive (correlation) one. Present results show that temperature changes in the medium can be observed even if the Green function (GF) of the medium is not reconstructed. Moreover, this article establishes that the GF reconstruction in the correlations is not a necessary condition: the only condition to monitoring with correlation (passive experiment) is the relative stability of the background noise structure

CSP for binary conservative relational structures

We prove that whenever A is a 3-conservative relational structure with only binary and unary relations then the algebra of polymorphisms of A either has no Taylor operation (i.e. CSP(A) is NP-complete), or generates a congruence meet semidistributive variety (i.e. CSP(A) has bounded width).Comment: 9 pages, 3 figure

The STAR MAPS-based PiXeL detector

The PiXeL detector (PXL) for the Heavy Flavor Tracker (HFT) of the STAR experiment at RHIC is the first application of the state-of-the-art thin Monolithic Active Pixel Sensors (MAPS) technology in a collider environment. Custom built pixel sensors, their readout electronics and the detector mechanical structure are described in detail. Selected detector design aspects and production steps are presented. The detector operations during the three years of data taking (2014-2016) and the overall performance exceeding the design specifications are discussed in the conclusive sections of this paper

On the reduction of the CSP dichotomy conjecture to digraphs

It is well known that the constraint satisfaction problem over general relational structures can be reduced in polynomial time to digraphs. We present a simple variant of such a reduction and use it to show that the algebraic dichotomy conjecture is equivalent to its restriction to digraphs and that the polynomial reduction can be made in logspace. We also show that our reduction preserves the bounded width property, i.e., solvability by local consistency methods. We discuss further algorithmic properties that are preserved and related open problems.Comment: 34 pages. Article is to appear in CP2013. This version includes two appendices with proofs of claims omitted from the main articl

Recruitment of young adults for weight gain prevention: randomized comparison of direct mail strategies

Abstract Background Recruiting young adults (ages 18–35 years) into weight gain prevention intervention studies is challenging and men are particularly difficult to reach. This paper describes two studies designed to improve recruitment for a randomized trial of weight gain prevention interventions. Study 1 used a quasi-experimental design to test the effect of two types of direct mailings on their overall reach. Study 2 used a randomized design to test the effect of using targeted messages to increase recruitment of men into the trial. Methods For Study 1, 60,000 male and female young-adult households were randomly assigned to receive either a recruitment brochure or postcard. Visits to recruitment websites during each mailing period were used to assess response to each mailing. Study 2 focused on postcard recruitment only. These households received either a targeted or generic recruitment postcard, where targeted postcards included the word “Men” in the headline text. Response rates to each type of card were categorized based on participant report of mailing received. Results The reach of the postcards and brochures were similar (421 and 386 website visits, respectively; P = 0.22). Individuals who received the brochure were more likely to initiate the online screener than those who received a postcard (P = 0.01). In Study 2, of those who completed the telephone screening, 60.9 % of men (n = 23) had received the targeted postcard as compared to the generic postcard (39.1 %, P = 0.30). The reverse was true for women (n = 62, 38.7 vs. 61.3 %, P = 0.08). Conclusions These studies suggest there was little difference in the reach of postcards versus brochures. However, recipients of brochures were more likely to continue to the next stage of study participation. As expected, men’s response to the weight gain prevention messages was lower than women’s response; but using targeted messages appears to have modestly increased the proportion of male respondents. These studies add to the limited experimental literature on recruitment messaging and provide further indication for using targeted messages to reach underrepresented populations while providing initial evidence on the effect of mailing type on message reach. Trial registration The Study of Novel Approaches to Weight Gain Prevention was registered with ClinicalTrials.gov (identifier: NCT01183689) on 13 August 2010

Effect of Tuned Parameters on a LSA MCQ Answering Model

This paper presents the current state of a work in progress, whose objective is to better understand the effects of factors that significantly influence the performance of Latent Semantic Analysis (LSA). A difficult task, which consists in answering (French) biology Multiple Choice Questions, is used to test the semantic properties of the truncated singular space and to study the relative influence of main parameters. A dedicated software has been designed to fine tune the LSA semantic space for the Multiple Choice Questions task. With optimal parameters, the performances of our simple model are quite surprisingly equal or superior to those of 7th and 8th grades students. This indicates that semantic spaces were quite good despite their low dimensions and the small sizes of training data sets. Besides, we present an original entropy global weighting of answers' terms of each question of the Multiple Choice Questions which was necessary to achieve the model's success.Comment: 9 page

Long-term prognosis and educational determinants of brain network decline in older adult individuals

Older adults with lower education are at greater risk for dementia. It is unclear which brain changes lead to these outcomes. Longitudinal imaging-based measures of brain structure and function were examined in adult individuals (baseline age, 45-86 years; two to five visits per participant over 1-9 years). College degree completion differentiates individual-based and neighborhood-based measures of socioeconomic status and disadvantage. Older adults (~65 years and over) without a college degree exhibit a pattern of declining large-scale functional brain network organization (resting-state system segregation) that is less evident in their college-educated peers. Declining brain system segregation predicts impending changes in dementia severity, measured up to 10 years past the last scan date. The prognostic value of brain network change is independent of Alzheimer\u27s disease (AD)-related genetic risk

Mitiq: A software package for error mitigation on noisy quantum computers

We introduce Mitiq, a Python package for error mitigation on noisy quantum computers. Error mitigation techniques can reduce the impact of noise on near-term quantum computers with minimal overhead in quantum resources by relying on a mixture of quantum sampling and classical post-processing techniques. Mitiq is an extensible toolkit of different error mitigation methods, including zero-noise extrapolation, probabilistic error cancellation, and Clifford data regression. The library is designed to be compatible with generic backends and interfaces with different quantum software frameworks. We describe Mitiq using code snippets to demonstrate usage and discuss features and contribution guidelines. We present several examples demonstrating error mitigation on IBM and Rigetti superconducting quantum processors as well as on noisy simulators

Non Destructive Evaluation of Containment Walls in Nuclear Power Plants

Two functions are regularly tested on the containment walls in order to anticipate a possible accident. The first is mechanical to resist at a possible internal over-pressure and the second is to prevent leakage. The reference accident LLOCA (Large Loss of Coolant Accident) is the rupture of a pipe in the primary circuit of a nuclear plant. In this case, the pressure and temperature can reach 5 bar and 180°C in 20 seconds. The national project ‘Non-destructive testing of the containment structures of nuclear plants’ aims at studying the non-destructive techniques capable to evaluate the concrete properties and its damaging or progression of cracks. This 4-year-project is segmented into two parts. The first consists in developing and selecting the most relevant NDEs (Non Destructive Evaluations) in the laboratory to reach these goals. These evaluations are developed in conditions representing the real conditions of the stresses generated during ten-yearly visits of the plants or those related to an accident. The second part consists in applying the selected techniques to two containment structures under pressure. The first (technique) is proposed by the ONERA (National Office for Aerospace Studies and Research of France) and the second is a mock-up of a containment wall on a 1/3 scale made by EDF (Electricity of France) within the VeRCoRs program. Communication bears on the part of the project that concerns the damaging and cracking follow-up. The tests are done in bending on 3 or 4 points in order to study the cracks’ generation, their propagation, as well as their opening and closing. The mostly ultrasonic techniques developed concern linear or non-linear acoustic: acoustic emission [1], LOCADIFF (Locating with diffuse ultrasound) [2], energy diffusion, surface waves velocity and attenuation, DAET (Dynamic Acousto-Elasticity Testing) [3]. The data contribute to providing the mapping of the parameters searched for, either in volume, in surface or globally. Image correlation is an important additional asset to validate the coherence of the data. The spatial normalization of the data allows proposing algorithms on the combination of the experimental data. The tests results are presented and they show the capacity and the limits of the evaluation of the volume, surface or global data. A data fusion procedure is associated with these results