The drunkard’s search: Looking for ‘HRM’ in all the wrong places

Abstract and Key Results

Slow light structures in dye-doped polymer waveguides

We present a simple and consistent technique for fabricating slow light structures in dye-doped polymer waveguides using the process of irreversible photobleaching. The slow light structures are moiré gratings. The gratings are holographically written into channel waveguides photobleached in side-chained PMMA/DR1 films. The films are annealed during the photobleaching process in order to remove stresses in the films generated during the photobleaching process. These stresses have been observed to cause distortion and cracking of the film surface. The slowing factor for the moiré gratings is calculated from the reflectance spectrum of the waveguides using the Hilbert transform. Moiré gratings with slowing factors between 1.6 and 2.6 are demonstrated.     

Mercuric ion sensing by a film bulk acoustic resonator

This paper describes a film bulk acoustic resonator (FBAR) mass sensor for detecting Hg2+ ion in water with excellent sensitivity and selectivity. When a thin Au film was deposited on the surface of an FBAR, the resonant frequency shifted to a lower value when the film was exposed to Hg2+ in aqueous solution. The FBAR sensor detected as low as 10(-9) M Hg2+ (0.2 ppb Hg2+) in water. Other ions such as K+, Ca2+, Mg2+, Zn2+, and Ni2+ had little or no effect on the resonant frequency of the FBAR. Coating of the FBAR Au surface with a self-assembled monolayer (SAM) of 4-mercaptobenzoic acid decreased the Hg2+ response.     

Self-assembled virus-like particles with magnetic cores

Efficient encapsulation of functionalized spherical nanoparticles by viral protein cages was found to occur even if the nanoparticle is larger than the inner cavity of the native capsid. This result raises the intriguing possibility of reprogramming the self-assembly of viral structural proteins. The iron oxide nanotemplates used in this work are superparamagnetic, with a blocking temperature of about 250 K, making these virus-like particles interesting for applications such as magnetic resonance imaging and biomagnetic materials. Another novel feature of the virus-like particle assembly described in this work is the use of an anionic lipid micelle coat instead of a molecular layer covalently bound to the inorganic nanotemplate. Differences between the two functionalization strategies are discussed.     

A model for predicting the power delay profile characteristicsinside a room

Multipath effects in indoor wireless communication systems exhibit a characteristic power delay profile (PDP) and can be a detriment to the system's performance. We present a simplified model for calculating the decay rate of the PDP for propagation within rooms. This simplified model provides a time-efficient means of predicting system performance. Predictions of this in-room PDP model are compared to results obtained from a finite-difference time-domain (FDTD) model. Additionally, comparisons of the IPDP model to measured data are presented. The RMS delay spread is the second central moment of the PDP of a propagation channel and is a measure of the communication link degradation due to multipath. We also show results of the estimated RMS delay spread from this model and show comparisons to the measured data. This IPDP model can be used to investigate the effects of variable room size and properties of the surfaces (or walls) on the decay characteristics of the PDP     

Psychosocial factors and the development of breast cancer: A meta-analysis.

A meta-analysis examined the relationship between psychosocial factors and the development of breast cancer. Average effect sizes (Hedges's g) were calculated from 46 studies for 8 major construct categories: anxiety/depression, childhood family environment, conflict-avoidant personality, denial/repression coping, anger expression, extraversion-introversion, stressful life events, and separation/loss. Significant effect sizes were found for denial/repression coping (g?=?.38), separation/loss experiences (g?=?.29), and stressful life events (g?=?.25). Although conflict-avoidant personality style was also significant (g?=?.19), the effect size was less robust, and a moderate number of future studies with null results would reduce the significance. Results overall support only a modest association between specific psychosocial factors and breast cancer and are contrary to the conventional wisdom that personality and stress influence the development of breast cancer. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Modeling of transfer phenomena on heterogeneous ziegler catalysts. II. Experimental investigation of intraparticle mass transfer resistance during the polymerization of ethylene in slurry

An experimental investigation of mass transfer limitations on a single batch of high activity, heterogeneous catalysts used in the slurry polymerization of ethylene is presented. The viscosity of the continuous phase was varied, using trace amounts of inert copolymer in order to reduce the monomer diffusivity, and the activity levels were varied using hexene as an activator. These changes were intended to clearly identify situations in which the polymerization becomes mass-transfer-limited due to diffusion resistance in the pores of the catalyst. Increasing the observed activity of the catalyst from approximately 9000 to 40,000 grams of polymer per gram of catalyst per hour (g/g/h) revealed no evidence of mass transfer resistance, even when the diffusivity of the monomer in solution was reduced by a factor of six. Analysis of the molecular weight as a function of particle size supported this conclusion but did suggest that there might be slight chemical differences between large and small particles. © 1996 John Wiley & Sons, Inc.     

High-intensity laser-driven proton acceleration: influence of pulse contrast

Proton acceleration from the interaction of ultra-short laser pulses with thin foil targets at intensities greater than 10(18) W cm(-2) is discussed. An overview of the physical processes giving rise to the generation of protons with multi-MeV energies, in well defined beams with excellent spatial quality, is presented. Specifically, the discussion centres on the influence of laser pulse contrast on the spatial and energy distributions of accelerated proton beams. Results from an ongoing experimental investigation of proton acceleration using the 10 Hz multi-terawatt Ti:sapphire laser (35f s, 35 TW) at the Lund Laser Centre are discussed. It is demonstrated that a window of amplified spontaneous emission (ASE) conditions exist, for which the direction of proton emission is sensitive to the ASE-pedestal preceding the peak of the laser pulse, and that by significantly improving the temporal contrast, using plasma mirrors, efficient proton acceleration is observed from target foils with thickness less than 50 nm.     

Characterization of pyrogenic black carbon by desorption atmospheric pressure photoionization Fourier transform ion cyclotron resonance mass spectrometry

We present a new method for molecular characterization of intact biochar directly, without sample preparation or pretreatment, on the basis of desorption atmospheric pressure photoionization (DAPPI) coupled to Fourier transform ion cyclotron resonance (FTICR) mass spectrometry. Conventional ionization methods (e.g., electrospray or atmospheric pressure photoionization) for characterization of natural organic matter have limited utility for the characterization of chars due to incomplete solubility in common solvents. Therefore, direct ionization techniques that do not require sample dissolution prior to analysis are ideal. Here, we apply DAPPI FTICR mass spectrometry to enable the first molecular characterization of uncharred parent oak biomass and after combustion (250 °C) or pyrolysis (400 °C). Parent oak is primarily composed of cellulose-, lignin-, and resin-like compounds. Oak combusted at 250 °C contains condensed aromatic compounds with low H/C and O/C ratios while retaining compounds with high H/C and O/C ratios. The bimodal distribution of aromatic and aliphatic compounds observed in the combusted oak sample is attributed to incomplete thermal degradation of lignin and hemicellulose. Pyrolyzed oak constituents exhibit lower H/C and O/C ratios: approximately three-quarters of the identified species are aromatic. DAPPI FTICR MS results agree with bulk elemental composition as well as functional group distributions determined by elemental analysis and solid state (13)C NMR spectroscopy. Complete molecular characterization of biomass upon thermal transformation may provide insight into the biogeochemical cycles of biochar and future renewable energy sources, particularly for samples currently limited by solubility, separation, and sample preparation.     

Evaluation of the University of Minnesota Tri-plate and 3M Petrifilm for the isolation of Staphylococcus aureus and Streptococcus species from clinically mastitic milk samples

The primary objective was to compare microbiological results of the University of Minnesota Tri-plate and the 3M Petrifilm Staph Express (STX) Count Plate to standard culture techniques for identification of clinical mastitis caused by Staphylococcus aureus. The secondary objective was to evaluate the Tri-plate's ability to differentiate Streptococcus spp. from other gram-positive organisms. The tests were evaluated using clinically positive mastitic milk samples (n = 282) to determine their ability to diagnose the pathogens of interest. A Tri-plate was classified positive for Staph. aureus when at least 1 colony exhibiting β-hemolysis was present on the Factor media portion of the plate. When the plate was used in this manner and read by a trained laboratory technician, the sensitivity of the Tri-plate was 97.9% and the specificity was 81.8%. When the Tri-plate was evaluated by the laboratory technician for its ability to diagnose Streptococcus spp., both sensitivity and specificity of the test were very good (92.6 and 89.5%, respectively). Using the Petrifilm, samples were classified as positive for Staph. aureus if any red-violet colonies were present on the Petrifilm after an initial 24-h incubation. When used in this manner, the Petrifilm had a sensitivity of 97.4% and a specificity of 76.1%. Further evaluation of the Petrifilm was done using the STX disk, which was used to confirm the presence of Staph. aureus. When using the presence of 1 pink colony on the disk, the sensitivity of the Petrifilm was 92.1% and the specificity was 93.1%. Both the Tri-plate and the 3M STX Petrifilm successfully diagnosed Staph. aureus in clinical milk samples when used in a laboratory setting and the Tri-plate successfully differentiated Streptococcus spp. from other gram-positive organisms.