Photoactivatable copolymers of vinylbenzyl thiocyanate as immobilization matrix for biochips

Biochip surfaces for immobilization of DNA and proteins require reactive polymers with high immobilization capacity and low nonspecific binding. Most reactive surfaces consist of matrixes that provide epoxy, aldehyde, or amino functions for biomolecule binding. The most widely used oligonucleotide modification is a C6-amino link. The high reactivity of isothiocyanate groups (NCS) toward amines was therefore the motivation to employ photogenerated NCS groups as binding sites for NH(2)-terminated oligonucleotides. Photosensitive poly(styrene-co-4-vinylbenzyl thiocyanate) (PST-co-VBT) was synthesized and applied as novel material for DNA and protein immobilization. The immobilization capacity of PST-co-VBT was a function of UV energy density used for photoactivation and was approximately 80% at 450 mJ cm(-)(2) (lambda(ex) = 254 nm). This surface was superior to tested commercial chip surfaces in signal-to-noise-ratio and reproducibility. Print buffer and spacer length were optimized for maximum fluorescence signal with DNA and proteins. UV exposure conditions and oligonucleotide modification were correlated, showing that this photochemical approach can be successfully applied for surface patterning of biochips.     

Seasonal changes in the sensitivity of river microalgae to atrazine and isoproturon along a contamination gradient

A study was undertaken to investigate the environmental impact of herbicides on natural communities of freshwater periphyton and phytoplankton in the river Ozanne and in related nearby water reservoirs, including both pristine and pesticide- (atrazine and isoproturon) contaminated stations. The microalgal toxicity of both herbicides was investigated by short-term studies, using the in vivo fluorescence pattern to perform dose-effect experiments. The taxonomic composition of the communities sampled was assessed by microscopy and by HPLC pigment analysis. The EC50 (periphyton) or EC125 (phytoplankton) values, calculated using in vivo fluorescence endpoints, increased with the herbicide concentration found in the water. In contrast, the structure of the algal communities (periphyton) inhabiting the contaminated stations seemed to be permanently affected when compared to the reference community. A 'memory effect' could be detected, both in herbicide sensitivity and in the structure of periphytic communities that persisted even when peak contaminations had disappeared. This study shows that the response of algal communities is likely to reflect past selection pressures, and suggests that the function and structure of a community could both be modified by the persistent or repeated presence of microcontaminants in natural environments. We could use short-term ecotoxicological tests on freshwater microalgae to assess the effects of past temporary contaminations by agricultural pesticides, and combining this with diversity indices could make it possible to assess the ecotoxicological risk of herbicide contamination even when a complete chemical analysis of the contamination is not feasible.     

Review of Understanding psychological research: An introduction to methods.

Reviews the book, Understanding psychological research: An introduction to methods by Richard St. Jean (2001). Richard St. Jean's book has the stated goal to be a brief text that presents essential concepts in a concise but interesting format. In this the author succeeds admirably. The nine short chapters and three appendices present the basic content that any method course needs to cover. The chapters are centred around lively research examples, often from the author's own work. Each chapter is followed by a brief summary and a glossary of key terms. The examples are used to introduce the methodological question and to illustrate various solutions. If the book suffers from a drawback, it is that it is too good at what it wants to be: an easily accessible, succinct introduction. The author visibly aims to make the issues as clear and understandable as possible, even if this implies glossing over details and leaving out more difficult aspects. The book does not want to be, nor is it, a manual for people who actual want to do research. In sum, this book will be most useful for those who teach introductory methods courses aimed at students who want to "consume" research rather than pursue it themselves. For these students, the book will be a valuable resource to better understand pertinent issues and to be alert towards methodological problems. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Correction to Debruille, Brodeur, and Hess (2011).

Reports an error in "Assessing the way people look to judge their intentions" by J. Bruno Debruille, Mathieu B. Brodeur and Ursula Hess (Emotion, 2011[Jun], Vol 11[3], 533-543). Figure 1 should have been printed in color. The online version has been corrected. (The following abstract of the original article appeared in record 2011-11794-006.) Faces of unknown persons are processed to infer the intentions of these persons not only when they depict full-blown emotions, but also at rest, or when these faces do not signal any strong feelings. We explored the brain processes involved in these inferences to test whether they are similar to those found when judging full-blown emotions. We recorded the event-related brain potentials (ERPs) elicited by faces of unknown persons who, when they were photographed, were not asked to adopt any particular expression. During the ERP recording, participants had to decide whether each face appeared to be that of a positively, negatively, ambiguously, or neutrally intentioned person. The early posterior negativity, the EPN, was found smaller for neutrally categorized faces than for the other faces, suggesting that the automatic processes it indexes are similar to those evoked by full-blown expressions and thus that these processes might be involved in the decoding of intentions. In contrast, in the same 200–400 ms time window, ERPs were not more negative at anterior sites for neutrally intentioned faces. Second, the peaks of the late positive potentials (LPPs) maximal at parietal sites around 700 ms postonset were not significantly smaller for neutrally intentioned faces. Third, the slow positive waves that followed the LPP were larger for faces that took more time to categorize, that is, for ambiguously intentioned faces. These three series of unexpected results may indicate processes similar to those triggered by full-blown emotions studies, but they question the characteristics of these processes. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Characterisation of within-batch and between-batch variability in microbial counts in foods using Poisson-gamma and Poisson-lognormal regression models

In modelling risk management strategies (i.e., acceptance sampling plans, statistical process control), two basic assumptions have been normally made: that the true concentration of microorganisms are log-normally distributed within a batch, and that the variance of the samples is the same for a little or highly contaminated lot. Within a heterogeneous Poisson theoretical framework, these two assumptions have been evaluated by characterising the between-batch and within-batch variability in microbial counts. To this effect, three variants of regressions (random effects for within-batch means only, correlated and uncorrelated random effects for within-batch means and spread measures) based on the Poisson-gamma (m,1/k) and the Poisson-lognormal (μ,σ) models were fitted to six microbial data sets of TVC, coliforms and Escherichia coli on pre-chill and post-chill beef carcasses sampled from different production batches. For the high counts data sets, the Poisson-lognormal regression with random effects for within-batch means (μ) provided a better model for the estimation of the within-batch and between-batch standard deviation; whereas for the low counts data sets, the Poisson-gamma regressions were superior for the characterisation of within-batch and between-batch variability. However, the selection of a complex Poisson-gamma model with correlated (m,1/k) random effects against a simple Poisson-gamma with variable means (m) depended on the extent of between-batch heterogeneity in the dispersion factor 1/k. The need to introduce the between-batch variability notion in risk management was further highlighted by assessing the real effectiveness of a hypothetical sampling plan operating under the best-fit correlated random effects Poisson-gamma approach, whereby the within-batch dispersion factor was variable and conditional on the within-batch mean.     

Move your virtual body: differences and similarities in brain activation patterns during hand movements in real world and virtual reality

Virtual Reality - Virtual reality (VR) is a promising tool for neurological rehabilitation, especially for motor rehabilitation. In the present study, we investigate whether brain activation...     

Neural Tissue Degeneration in Rosenthal’s Canal and Its Impact on Electrical Stimulation of the Auditory Nerve by Cochlear Implants: An Image-Based Modeling Study

Sensorineural deafness is caused by the loss of peripheral neural input to the auditory nerve, which may result from peripheral neural degeneration and/or a loss of inner hair cells. Provided spiral ganglion cells and their central processes are patent, cochlear implants can be used to electrically stimulate the auditory nerve to facilitate hearing in the deaf or severely hard-of-hearing. Neural degeneration is a crucial impediment to the functional success of a cochlear implant. The present, first-of-its-kind two-dimensional finite-element model investigates how the depletion of neural tissues might alter the electrically induced transmembrane potential of spiral ganglion neurons. The study suggests that even as little as 10% of neural tissue degeneration could lead to a disproportionate change in the stimulation profile of the auditory nerve. This result implies that apart from encapsulation layer formation around the cochlear implant electrode, tissue degeneration could also be an essential reason for the apparent inconsistencies in the functionality of cochlear implants.