Multiple proton translocation in biomolecular systems: concerted to stepwise transition in a simple model

In this paper we study a simple model potential energy surface (PES) useful for describing multiple proton translocation mechanisms. The approach presented is relevant to the study of more complex biomolecular systems like enzymes. In this model, at low temperatures, proton tunnelling favours a concerted proton transport mechanism, while at higher temperatures there is a crossover from concerted to stepwise mechanisms; the crossover temperature depends on the energetic features of the PES. We illustrate these ideas by calculating the crossover temperature using energies taken from ab initio calculations on specific systems. Interestingly, typical crossover temperatures lie around room temperature; thus both concerted and stepwise reaction mechanisms should play an important role in biological systems, and one can be easily turned into another by external means such as modifying the temperature or the pH, thus establishing a general mechanism for modulation of the biomolecular function by external effectors.

Common community-acquired infections and subsequent risk of multiple myeloma: a population-based study

The role of bacteria and viruses as aetiological agents in the pathogenesis of cancer has been well established for several sites, including a number of haematological malignancies. Less clear is the impact of such exposures on the subsequent development of multiple myeloma (MM). Using the population-based U.S. Surveillance Epidemiology and End Results-Medicare dataset, 15,318 elderly MM and 200,000 controls were identified to investigate the impact of 14 common community-acquired infections and risk of MM. Odds ratios (ORs) and associated 95% confidence intervals (CIs) were adjusted for sex, age and calendar year of selection. The 13-month period prior to diagnosis/selection was excluded. Risk of MM was increased by 5-39% following Medicare claims for eight of the investigated infections. Positive associations were observed for several infections including bronchitis (adjusted OR 1.14, 95% CI 1.09-1.18), sinusitis (OR 1.15, 95% CI 1.10-1.20) pneumonia (OR 1.27, 95% CI 1.21-1.33), herpes zoster (OR 1.39, 95% CI 1.29-1.49) and cystitis (OR 1.09, 95% CI 1.05-1.14). Each of these infections remained significantly elevated following the exclusion of more than 6 years of claims data. Exposure to infectious antigens may therefore play a role in the development of MM. Alternatively, the observed associations may be a manifestation of an underlying immune disturbance present several years prior to MM diagnosis and thereby part of the natural history of disease progression.

Partial shoeprint retrieval using multiple point-of-interest detectors and SIFT descriptors

Shoeprint evidence collected from crime scenes can play an important role in forensic investigations. Usually, the analysis of shoeprints is carried out manually and is based on human expertise and knowledge. As well as being error prone, such a manual process can also be time consuming; thus affecting the usability and suitability of shoeprint evidence in a court of law. Thus, an automatic system for classification and retrieval of shoeprints has the potential to be a valuable tool. This paper presents a solution for the automatic retrieval of shoeprints which is considerably more robust than existing solutions in the presence of geometric distortions such as scale, rotation and scale distortions. It addresses the issue of classifying partial shoeprints in the presence of rotation, scale and noise distortions and relies on the use of two local point-of-interest detectors whose matching scores are combined. In this work, multiscale Harris and Hessian detectors are used to select corners and blob-like structures in a scale-space representation for scale invariance, while Scale Invariant Feature Transform (SIFT) descriptor is employed to achieve rotation invariance. The proposed technique is based on combining the matching scores of the two detectors at the score level. Our evaluation has shown that it outperforms both detectors in most of our extended experiments when retrieving partial shoeprints with geometric distortions, and is clearly better than similar work published in the literature. We also demonstrate improved performance in the face of wear and tear. As matter of fact, whilst the proposed work outperforms similar algorithms in the literature, it is shown that achieving good retrieval performance is not constrained by acquiring a full print from a scene of crime as a partial print can still be used to attain comparable retrieval results to those of using the full print. This gives crime investigators more flexibility is choosing the parts of a print to search for in a database of footwear.

Following instructions in a virtual school: Does working memory play a role?

Accumulating evidence that working memory supports the ability to follow instructions has so far been restricted to experimental paradigms that have greatly simplified the practical demands of performing actions to instructions in everyday tasks. The aim of the present study was to investigate whether working memory is involved in maintaining information over the longer periods of time that are more typical of everyday situations that require performing instructions to command. Forty-two children 7–11 years of age completed assessments of working memory, a real-world following-instructions task employing 3-D objects, and two new computerized instruction-following tasks involving navigation around a virtual school to complete a sequence of practical spoken commands. One task involved performing actions in a single classroom, and the other, performing actions in multiple locations in a virtual school building. Verbal working memory was closely linked with all three following-instructions paradigms, but with greater association to the virtual than to the real-world tasks. These results indicate that verbal working memory plays a key role in following instructions over extended periods of activity.