Dynamic factors and force-weighting corrections influence estimates of cumulative vertebral joint compression

Estimates of cumulative load are typically based on a direct integration of instantaneous compressive loads. Recent evidence suggests that higher loads as well as smaller rest to work durations should receive greater importance in the calculation of cumulative compressive load, especially if insight into potential injury mechanisms is sought. The purpose of this investigation was to determine the effects that a novel weighting factor protocol would have on cumulative compressive load estimates using three different biomechanical models applied to a repetitive lifting task. Bilateral electromyographic activity of the external abdominal obliques and lumbar erector spinae, as well as unilateral kinematics of the upper body were collected from eight male and eight female participants while they performed a 5-min repetitive lifting/lowering task at a rate of one lift/lower every 6 seconds. Two-dimensional reaction L5/S1 joint kinetics were calculated using each of a static, quasi-static and dynamic linked segment model; muscular contributions to L5/S1 compression were computed using a single equivalent muscle model. Unweighted and weighted cumulative compression was calculated for each model type. Application of the weighting factor increased the estimates of cumulative compression for both the male and female participants. Since the males in this study loaded their spines to a relatively higher percentage of their predicted compressive strength when lifting/lowering, the effects of weighting instantaneous compressive loads had a greater influence on cumulative load magnitudes in males. A consistent finding between genders was that estimates of cumulative compressive joint loads from the dynamic model were most affected by applying weighting factors, as the inclusion of inertial information in the calculations lead to greater predicted compressive forces relative to estimated compressive strength. These findings suggest that biomechanical modelling assumptions made and the gender of the participants tested could influence interpretations drawn from studies using force-weighting approaches to understand potential injury mechanisms associated with cumulative exposures. Future work is needed to explore more thoroughly the influence of different rest to work durations on weighted cumulative load estimates.     

Effect of bark beetle infestation on secondary organic aerosol precursor emissions

Bark beetles are a potentially destructive force in forest ecosystems; however, it is not known how insect attacks affect the atmosphere. The emissions of volatile organic compounds (VOCs) were sampled i.) from bark beetle infested and healthy lodgepole pine (Pinus contorta var. latifolia) trees and ii.) from sites with and without active mountain pine beetle infestation. The emissions from the trunk and the canopy were collected via sorbent traps. After collection, the sorbent traps were extracted with hexane, and the extracts were separated and detected using gas chromatography/mass spectroscopy. Canister samples were also collected and analyzed by a multicolumn gas chromatographic system. The samples from bark beetle infested lodgepole pine trees suggest a 5- to 20-fold enhancement in total VOCs emissions. Furthermore, increases in the β-phellandrene emissions correlated with bark beetle infestation. A shift in the type and the quantity of VOC emissions can be used to identify bark beetle infestation but, more importantly, can lead to increases in secondary organic aerosol from these forests as potent SOA precursors are produced.     

Silver Nanoparticles Inhibit Sodium Uptake in Juvenile Rainbow Trout (Oncorhynchus mykiss)

The silver ion (Ag(+)) is well documented to be a potent inhibitor of sodium (Na(+)) transport in fish. However, it has not been determined whether silver nanoparticles (Ag NPs) elicit this same effect and, if so, if the NP itself and/or the dissociation of ionic Ag(+) causes this effect. Citrate-capped Ag NPs were dialyzed in water to determine the dissolution rate of ionic Ag(+) from the NPs and the maximum concentration of free Ag(+) released from the NPs was used as a paired Ag(+) control to distinguish NP effects from ionic metal effects. The maximum concentration of ionic Ag(+) released from these NPs over 48 h was 0.02 μg l(-1). Juvenile rainbow trout were exposed to 1.0 mg l(-1) citrate-capped Ag NPs and dialyzed citrate-capped Ag NPs or 10 μg l(-1) and 0.02 μg l(-1) ionic Ag(+) (as AgNO(3)) as controls. Both nondialyzed and dialyzed Ag NPs and 10 μg l(-1) ionic Ag(+) significantly inhibited unidirectional Na(+) influx by over 50% but had no effect on unidirectional Na(+) efflux. Na(+),K(+)-ATPase was significantly inhibited by the Ag NPs with no discernible effect on carbonic anhydrase activity. This study is the first to show that sodium regulation is disrupted by the presence of citrate-capped Ag NPs, and the results suggest that there are nanospecific effects.     

A Multiwalled‐Carbon‐Nanotube‐Based Biosensor for Monitoring Microcystin‐LR in Sources of Drinking Water Supplies

A multiwalled carbon nanotube (MWCNT)‐based electrochemical biosensor is developed for monitoring microcystin‐LR (MC‐LR), a toxic cyanobacterial toxin, in sources of drinking water supplies. The biosensor electrodes are fabricated using vertically well‐aligned, dense, millimeter‐long MWCNT arrays with a narrow size distribution, grown on patterned Si substrates by water‐assisted chemical vapor deposition. High temperature thermal treatment (2500 °C) in an Ar atmosphere is used to enhance the crystallinity of the pristine materials, followed by electrochemical functionalization in alkaline solution to produce oxygen‐containing functional groups on the MWCNT surface, thus providing the anchoring sites for linking molecules that allow the immobilization of MC‐LR onto the MWCNT array electrodes. Addition of the monoclonal antibodies specific to MC‐LR in the incubation solutions offers the required sensor specificity for toxin detection. The performance of the MWCNT array biosensor is evaluated using micro‐Raman spectroscopy, including polarized Raman measurements, X‐ray photoelectron spectroscopy, cyclic voltammetry, optical microscopy, and Faradaic electrochemical impedance spectroscopy. A linear dependence of the electron‐transfer resistance on the MC‐LR concentration is observed in the range of 0.05 to 20 μg L^?1, which enables cyanotoxin monitoring well below the World Health Organization (WHO) provisional concentration limit of 1 μg L^?1 for MC‐LR in drinking water.     

Quantitative analysis of human ras localization and function in the fission yeast Schizosaccharomyces pombe

Ras signalling is central to fundamental and diverse cellular processes. In higher eukaryotes ras signalling is highly complex, involving multiple isoforms, regulatory proteins and effectors. As a consequence, the study of ras activity in mammalian systems presents a number of technical challenges. The model organism Schizosaccharomyces pombe has previously proved a key system for the study of human signalling components and provides an ideal model for the study of ras, as it contains just one ras protein (Ras1p), which is non‐essential and controls a number of downstream processes. Here we present data demonstrating the quantitative analysis of three distinct Ras1‐related signalling outputs, utilizing the three most abundant human ras isoforms, H‐Ras, N‐Ras and K‐Ras4B, in Sz. pombe. Further, we have characterized the localization of these three human ras isoforms in Sz. pombe, utilizing quantitative image analysis techniques. These data indicate that all three human ras isoforms are functional in fission yeast, displaying differing localization patterns which correlate strongly with function in the regulation of pheromone response and cell shape. These data demonstrate that such yeast strains could provide powerful tools for the investigation of ras biology, and potentially in the development of cancer therapies. Copyright © 2013 John Wiley & Sons, Ltd.     

Structure and properties of melt-processed PVDF/PMMA/polyaniline blends

Ternary blends composed of the matrix polymer poly(vinylidene fluoride) (PVDF) and poly(methyl methacrylate) (PMMA) with different proportions of thermally doped polyaniline (PAni) using an alkylated dopant (dodecylbenzenesulfonic acid) (DBSA) were prepared by melt mixing. The effectiveness of these blends was compared with the corresponding binary blends of PVDF or PMMA with PAni–DBSA complex. Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD) measurements, thermal analysis by differential scanning calorimetry (DSC) and morphological studies by optical microscopy and scanning electron microscopy (SEM) were carried out to characterize the blends in light of the interactions between their components and on the resulting electrical conductivity. Though a notable dispersion of PAni–DBSA in the PMMA matrix was incurred along with better conductivity with respect to PVDF/PAni–DBSA and PVDF/PMMA/PAni–DBSA blends, the thin films based on PMMA/PAni–DBSA were found to be fragile in nature. However, the presence of PMMA in the ternary blends of PVDF/PMMA/PAni–DBSA provided improved dispersion of PAni–DBSA in the PVDF/PMMA host matrix as compared to PVDF/PAni–DBSA binary blends. An enhancement in the conductivity by about two orders of magnitude at >5 wt% PAni–DBSA was witnessed in the ternary blends than that of PVDF/PAni–DBSA binary blends. Thin films made of ternary blends of PVDF/PMMA/PAni–DBSA also offered superior mechanical properties and flexibility than that of PMMA/PAni–DBSA binary blends due to the contribution of PVDF in the blend.     

Selective attention to negative feedback in Type A and Type B individuals.

In a study with 16 Type A (coronary prone) and 16 Type B (noncoronary prone) undergraduates, chosen by scores on the Jenkins Activity Survey, Ss were given a 4-min opportunity to gain feedback of their ostensible negative liabilities and positive assets. Specific asset and liability feedback was bogus and was held constant across all Ss. The amount of time spent in attending to negative information was the key dependent measure. Results show that Type A Ss selectively attended to significantly more negative information than did Type B Ss. It is suggested that selective attention to liability may exacerbate and/or maintain the Type A individual's belief of personal inadequacy and that this personal belief may in turn foster selective attention to liabilities. (8 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Alcohol cue reactivity, negative-mood reactivity, and relapse in treated alcoholic men.

Relapsed alcoholic individuals frequently report that negative emotional states trigger their return to drinking. A parametric laboratory study was conducted to assess the separate and combined effects of exposure to alcohol-related stimuli and induced negative moods in abstinent alcoholic persons. The authors also sought to determine if reactivity to alcohol cues or reactivity to negative mood induction predicted relapse soon after treatment. Men with alcoholism (N?=?50) undergoing inpatient treatment participated in a guided imagery procedure designed to induce negative moods and were then exposed to either their favorite alcoholic beverage or to spring water. Results indicated that both alcoholic beverage presentation and negative affect imagery led to increased subjective reporting of desire to drink. These effects were additive but not multiplicative (i.e., the interaction of mood state with beverage type was not significant). Reported urge to drink during the trial that combined negative mood imagery with alcoholic beverage exposure predicted time to relapse after inpatient discharge. (PsycINFO Database Record (c) 2010 APA, all rights reserved)