Carbon‐Nanotube–PDMS Composite Coatings on Optical Fibers for All‐Optical Ultrasound Imaging

Polymer–carbon nanotube composite coatings have properties that are desirable for a wide range of applications. However, fabrication of these coatings onto submillimeter structures with the efficient use of nanotubes has been challenging. Polydimethylsiloxane (PDMS)–carbon nanotube composite coatings are of particular interest for optical ultrasound transmission, which shows promise for biomedical imaging and therapeutic applications. In this study, methods for fabricating composite coatings comprising PDMS and multiwalled carbon nanotubes (MWCNTs) with submicrometer thickness are developed and used to coat the distal ends of optical fibers. These methods include creating a MWCNT organogel using two solvents, dip coating of this organogel, and subsequent overcoating with PDMS. These coated fibers are used as all‐optical ultrasound transmitters that achieve high ultrasound pressures (up to 21.5 MPa peak‐to‐peak) and broad frequency bandwidths (up to 39.8 MHz). Their clinical potential is demonstrated with all‐optical pulse‐echo ultrasound imaging of an aorta. The fabrication methods in this paper allow for the creation of thin, uniform carbon nanotube composites on miniature or temperature‐sensitive surfaces, to enable a wide range of advanced sensing capabilities.     

Modified Goodness-of-Fit Tests for Gamma Distributions with Unknown Location and Scale Parameters

The common Kolmogorov-Smirnov, Anderson-Darling, and Cramer-von Mises goodness-of-fit tests require continuous underlying distributions with known parameters. This paper gives tables of critical values for these tests for gamma distributions with unknown location and scale parameters and known shape parameters. The powers of these tests are given for a number of alternative distributions. A relation between the critical values and the inverse square of the shape parameter is presented. For larger sample sizes, the modified CvM test is usually the most powerful of the three tests. One exception is for the alternative of a lognormal distribution where the modified AD test is most powerful. The equation, C = ao + a1(1/?2) describes the relation between critical value and shape parameter quite well.     

A Multichannel Signal Processor for the Detection of Epileptogenic Sharp Transients in the EEG

A high-speed multichannel signal processing system is described which is capable of performing automated detection of epileptogenic sharp transients (ST) in the electroencephalogram (EEG). The system is implemented with individually programmable microprocessors on the input channels, followed by a single-board microcomputer which correlates results obtained from each channel, and can process data played back from a tape recorder at a speed eight times the realtime recording speed. A multichannel correlation algorithm is used to enhance the performance of the system in the presence of muscle artifact (EMG). Results are presented showing that the multichannel correlation is capable of reducing, in some cases, both missed detections due to poorly defined ST's and false alarms due to EMG.     

Influence of Si:Al ratio on the microstructural and mechanical properties of a fine-limestone aggregate alkali-activated slag concrete

Three series of fine limestone aggregate, alkali-activated blast furnace slag (AAS) concretes were fabricated and tested; two through activation with waterglass/NaOH solution, of which one included NaCl as a retarding agent, and one activated by Na₂CO₃. Each of these series was made up of three formulae containing different amounts of Al₂O₃. The compressive strengths of the series activated by waterglass/NaOH after 28 days were ≈65 ± 5.3 MPa, a 22% increase compared to previously reported formulae containing no additional Al₂O₃. Increasing the amount of Al₂O₃ did not further increase strength, however. The Na₂CO₃-activated formulae had strengths of ≈35 ± 3 MPa after 28 days, representing no increase in strength over formulae not containing Al₂O₃ previously reported. X-ray diffraction showed the main binding phase to be calcium silicate hydrate (C–S–H) gel, as is commonly found in ordinary Portland cement (OPC). Fourier transform infrared spectroscopy showed little difference from the previously reported results for formulae not containing Al₂O₃ and strongly resemble the spectra reported elsewhere for C–S–H. Electron microscopy, coupled with energy dispersive spectroscopy, showed the cementing phase to be a single homogenous phase—not a mixed system of geopolymer and C–S–H gel—with a lower volume fraction of unreacted slag than formulae without Al₂O₃. The reason for the increase in strength of Al₂O₃-containing formulae is unclear, but is unlikely to be ascribed to the formation of large amounts of ‘geopolymers’ and may be related to a possible increase in reaction temperature of between 2 and 5°C, depending on amount of additive.     

Cost-effectiveness of self-help smokeless tobacco cessation programs.

This study assessed the cost-effectiveness of two low-intensity programs for quitting smokeless tobacco, based on results of a randomized trial with 1,069 volunteer participants. Cost data were collected for two levels of intervention: manual only (a self-help manual) and assisted self-help (the manual plus a videotape and two supportive phone calls from tobacco cessation counselors). Incremental cost-effectiveness ratios were calculated for assisted self-help vs. quitting on one's own, using the manual-only quit rate and data from another study as alternative proxies for no intervention. A threshold analysis was conducted to determine the spontaneous quit rate at which the manual-only intervention becomes more cost-effective than assisted self-help. The cost to provide and receive the assisted self-help intervention averaged US $56 per participant vs. $20 for the manual-only intervention (societal perspective, Year 2000 dollars). Estimates for incremental cost per quit for the assisted self-help intervention ranged from $922 to $1,758, depending on the proxy used for no intervention. The manual-only intervention was more cost-effective than assisted self-help if quitting among motivated chewers who do not receive treatment does not exceed 3.4%. Support from a wife or partner added little cost to a quit attempt for male chewers ($3-$4). Providing a manual, video, and brief phone counseling to smokeless tobacco users who want to quit is a reasonable use of health care resources. The self-help quitting guide also may be a cost-effective treatment, but it remains to be demonstrated whether it is more effective than quitting on one's own.     

Silver nanoparticles: A novel antibacterial agent for control of Cronobacter sakazakii

Silver nanoparticles (AgNP) have been widely applied because of their broad spectrum of antimicrobial activities against bacteria, fungi, and viruses. However, little research has been done to evaluate their effects on Cronobacter sakazakii, an opportunistic pathogen usually infecting infants and having a high fatality rate. The aims of this work were to investigate the antibacterial property of novel, synthesized, positively charged silver nanoparticles against C. sakazakii and to discuss the potential antibacterial mechanisms involved. In this study, the spherical and face-centered cubic silver nanoparticles had a mean particle size of 31.2 nm and were synthesized by reducing Ag⁺ using citrate and dispersed by glycerol and polyvinylpyrrolidone (PVP) under alkaline conditions. Minimum inhibitory concentrations (MIC) and inhibition zone tests showed that the AgNP exhibited strong antibacterial activity against 4 tested C. sakazakii strains with mean MIC of 62.5 to 125 mg/L and average inhibition zone diameters of 13.8 to 16.3 mm. Silver nanoparticles caused cell membrane injury accompanied by adsorption of AgNP onto the cell surface, as shown by changes in cell morphology, cell membrane hyperpolarization, and accelerated leakage of intracellular reducing sugars and proteins outward from the cytoplasm. In addition, dysfunction of the respiratory chain was induced after treatment with AgNP, which was supported by a decrease in intracellular ATP and inhibition of related dehydrogenases. This research indicates that AgNP could be a novel and efficient antibacterial agent to control C. sakazakii contamination in environments producing powdered infant formulas from milk.     

Assessing the conversational behaviour of psychiatric patients: Reliability and validity of the Verbal Report Form (VRF).

Two studies investigated the reliability and validity of a new behavioral rating scale, the Verbal Report Form (VRF), which measures brief unstructured verbal interactions of chronic mental patients. In Study 1, 6 individuals familiar with the VRF rated 12 videotaped segments (differing in length) of chronic schizophrenic patients. Results indicate that a 2-min time segment was necessary to accurately assess conversational behavior (mean rater agreement = .76). In Study 2, 15 raters (5 psychologists, 5 psychiatric technicians, and 5 nonprofessionals) rated 15 2-min video-tapes of verbal behavior (5 hospitalized patients, 5 board and care residents, and 5 normals). Results of an analysis of variance suggest that the VRF could significantly discriminate among the 3 contrasting groups using the number of inappropriate responses rated. Results are discussed in terms of differences between raters and difference in the discriminability of the categories of the VRF. (1 p ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A screening inventory for assessing psychiatric impairment in children 6 to 18.

Administered a structured questionnaire to a cross-sectional sample of 1,034 mothers and a welfare sample of 1,000 mothers of 6-18 yr olds in New York City. One or more psychiatrists rated each of the children on a 5-point scale of total psychiatric impairment. Factor analysis of the questionnaire items of child behavior yielded 18 factors. The 7 factors with the highest correlations with total psychiatric impairment were selected for the inventory, each represented by 5 items. The correlation of the total 35-item score and total psychiatric impairment was .82. The screening inventory significantly and substantially improved over chance in assigning children to impairment statuses in the cross-sectional sample and the sample used for cross-validation, the welfare sample. Correlations of the total score with child's treatment status and a direct clinical examination rating were expectedly low. In its present form, the instrument is recommended only for comparisons of different child and adolescent groups. (25 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)