Direct measurement of shear-induced cross-correlations of Brownian motion

Shear-induced cross-correlations of particle fluctuations perpendicular and along stream-lines are investigated experimentally and theoretically. Direct measurements of the Brownian motion of micron-sized beads, held by optical tweezers in a shear-flow cell, show a strong time-asymmetry in the cross-correlation, which is caused by the non-normal amplification of fluctuations. Complementary measurements on the single particle probability distribution substantiate this behavior and both results are consistent with a Langevin model. In addition, a shear-induced anti-correlation between orthogonal random-displacements of two trapped and hydrodynamically interacting particles is detected, having one or two extrema in time, depending on the positions of the particles.Comment: 4 pages, 4 figure

Drug-drug interactions in an intensive care unit of a tertiary hospital in southern Chile: Evaluating databases agreement

Context: Patients in intensive care units have a high risk of experiencing a pharmacological interaction due to complex pharmacotherapy, severe disease, and comorbidities; increasing the risk of adverse effects of medications. Electronic databases are useful sources to identify drug-drug interactions (DDI), especially when new therapeutic alternatives are added to conventional treatments. Aim: To identify the frequency and severity of potential drug-drug interactions (pDDIs) in ICU patients using three electronic databases. Methods: Clinical pharmacists collected data on medication dosage and route of administration, sex, age, length of stay, comorbidities, and APACHE II score using patient records. Micromedex, Medscape, and Lexicomp databases were used to identify and categorize pDDIs. Intensivists confirmed if a pDDI was clinically present. kappa concordance test was utilized as a measure of agreement among databases. Results: Of the 93 ICU patients studied, pDDIs were identified in 89. A positive incremental relationship was found between number of medications, length of stay, and number of pDDIs. Patients with respiratory pathologies were most predisposed to presenting DDIs. Agreement among databases was mixed. Intensivists confirmed 5% of pDDIs. Conclusions: Discrepancies among databases and in intensivist judgment highlight a significant information gap in the identification of DDIs

Search for an interaction mediated by axion-like particles with ultracold neutrons at the PSI

We report on a search for a new, short-range, spin-dependent interaction using a modified version of the experimental apparatus used to measure the permanent neutron electric dipole moment at the Paul Scherrer Institute. This interaction, which could be mediated by axion-like particles, concerned the unpolarized nucleons (protons and neutrons) near the material surfaces of the apparatus and polarized ultracold neutrons stored in vacuum. The dominant systematic uncertainty resulting from magnetic-field gradients was controlled to an unprecedented level of approximately 4 pT/cm using an array of optically-pumped cesium vapor magnetometers and magnetic-field maps independently recorded using a dedicated measurement device. No signature of a theoretically predicted new interaction was found, and we set a new limit on the product of the scalar and the pseudoscalar couplings $g_sg_p\lambda^2 < 8.3 \times 10^{-28}\,\text{m}^2$ (95% C.L.) in a range of $5\,\mu\text{m} < \lambda < 25\,\text{mm}$ for the monopole-dipole interaction. This new result confirms and improves our previous limit by a factor of 2.7 and provides the current tightest limit obtained with free neutrons

A cluster analysis of natural beef product consumers by shopping behavior, importance of production attributes, and demographics

Analyzes consumer segments based on their interest and willingness-to-pay for various natural beef products using cluster analysis. Trends in consumer food purchasing; Review of literature on consumer interest in food purchasing; Summary statistics of the socio-demographic information on consumers.Amanda Ziehl, Dawn D. Thilmany, and Wendy Umberge

Detection of active corrosion in reinforced and prestressed concrete: overview of NIST TIP project

The US transportation infrastructure has been receiving intensive public and private attention in recent years. The Federal Highway Administration estimates that 42 percent of the nearly 600,000 bridges in the Unites States are in need of structural or functional rehabilitation1. Corrosion of reinforcement steel is the main durability issue for reinforced and prestressed concrete structures, especially in coastal areas and in regions where de-icing salts are regularly used. Acoustic Emission (AE) has proved to be a promising method for detecting corrosion in steel reinforced and prestressed concrete members. This type of non-destructive test method primarily measures the magnitude of energy released within a material when physically strained. The expansive ferrous byproducts resulting from corrosion induce pressure at the steel-concrete interface, producing longitudinal and radial microcracks that can be detected by AE sensors. In the experimental study presented herein, concrete block specimens with embedded steel reinforcing bars and strands were tested under accelerated corrosion to relate the AE activity with the onset and propagation stages of corrosion. AE data along with half cell potential measurements and galvanic current were recorded to examine the deterioration process. Finally, the steel strands and bars were removed from the specimens, cleaned and weighed. The results were compared vis-a-vis Faraday's law to correlate AE measurements with degree of corrosion in each block

Status in the development of self-powered wireless sensor node for structural health monitoring and prognosis

This paper discusses the development status of a self-powered wireless sensor node for steel and concrete bridges monitoring and prognosis. By the end of the third year in this four-year cross-disciplinary project, the 4-channel acoustic emission wireless node, developed by Mistras Group Inc, has already been deployed in concrete structures by the University of Miami. Also, extensive testing is underway with the node powered by structural vibration and wind energy harvesting modules developed by Virginia Tech. The development of diagnosis tools and models for bridge prognosis, which will be discussed in the paper, continues and the diagnosis tools are expected to be programmed in the node's AVR during the 4th year of the project. The impact of this development extends beyond the area of bridge health monitoring into several fields, such as offshore oil platforms, composite components on military ships and race boats, combat deployable bridges and wind turbine blades. Some of these applications will also be discussed. This project was awarded to a joint venture formed by Mistras Group Inc, Virginia Tech, University of South Carolina and University of Miami by the National Institute of Standards and Technology through its Technology Innovation Program Grant #70NANB9H007