Dynamic programming generation of curves on brain surfaces

Dynamic programming algorithms are presented for automated generation of length minimizing geodesics and curves of extremal curvature on the neocortex of the macaque and the visible human. Probabilistic models of curve variation are constructed in terms of the variability in speed, curvature, and torsion in the Frenet representation     

Control aspects of quantum computing using pure and mixed states

Steering quantum dynamics such that the target states solve classically hard problems is paramount to quantum simulation and computation. And beyond, quantum control is also essential to pave the way to quantum technologies. Here, important control techniques are reviewed and presented in a unified frame covering quantum computational gate synthesis and spectroscopic state transfer alike. We emphasize that it does not matter whether the quantum states of interest are pure or not. While pure states underly the design of quantum circuits, ensemble mixtures of quantum states can be exploited in a more recent class of algorithms: it is illustrated by characterizing the Jones polynomial in order to distinguish between different (classes of) knots. Further applications include Josephson elements, cavity grids, ion traps and nitrogen vacancy centres in scenarios of closed as well as open quantum systems.     

Collapse behavior evaluation of asymmetric buildings subjected to bi‐directional ground motion

This paper discusses the collapse behavior of low‐rise plan‐asymmetric buildings under bi‐directional horizontal ground motions and utilizing strength and stiffness degrading nonlinear models. For this purpose, three‐dimensional three‐story and six‐story reinforced concrete frame buildings with uni‐directional mass eccentricities equal to 0% (symmetrical), 10%, 20% and 30% are subjected to nonlinear static (pushover) as well as incremental dynamic analyses using a set of far‐field two‐component ground motions and their performance are assessed on the basis of the safety margin against collapse and its probability of occurrence. Comparison of the collapse margin ratios as well as the fragility curves demonstrates significant reduction of the collapse‐level ground motion intensity with increasing eccentricity in plan. Results also indicate that current seismic design parameters including the response modification (R), overstrength (Ω) and ductility (μ) factors are not appropriate for buildings with high levels of plan eccentricity. Buildings with high values of plan eccentricity do not meet the design target life safety performance level on the basis of the calculated probability of collapse and safety margin against collapse. It appears that re‐evaluation of their design parameters is necessary. Copyright © 2015 John Wiley & Sons, Ltd.     

Antimicrobial resistance of bacterial flora associated with bovine products in South Africa.

The administration of subtherapeutic doses of antibiotics to livestock introduces selective pressures that may lead to the emergence and dissemination of resistant bacteria. This study determined the antibiotic-resistance spectra of the microbial flora found on freshly slaughtered and retail beef and in unpasteurized and pasteurized packaged milk. Staphylococci, Enterobacteriaeae, and isolates from total aerobic plate counts were tested for resistance to vancomycin, streptomycin, methicillin, tetracycline, and gentamicin using the disc diffusion susceptibility test and resistance to penicillin was determined by using oxacillin. A larger proportion of resistance to most antibiotics, except for vancomycin, was displayed by isolates from abattoir samples. The incidence of multiple antibiotic resistance (MAR) pathogenic bacteria is also higher in the abattoir. Resistance genes lost because of lack of selective pressure or resistant flora being replaced by more sensitive flora during processing is the reason for the lower incidence of MAR pathogenic bacteria among retail samples. These resistant bacteria can be transferred to humans through the consumption of rare or raw beef and unpasteurized milk, thus rendering the resultant food-related infections difficult to treat. The present findings clearly demonstrate that antibiotic-resistant bacteria in beef and milk pose a serious problem in South Africa.     

Statistical methods in computational anatomy

This paper reviews recent developments by the Washington/Brown groups for the study of anatomical shape in the emerging new discipline of computational anatomy. Parametric representations of anatomical variation for computational anatomy are reviewed, restricted to the assumption of small deformations. The generation of covariance operators for probabilistic measures of anatomical variation on coordinatized submanifolds is formulated as an empirical procedure. Populations of brains are mapped to common coordinate systems, from which template coordinate systems are constructed which are closest to the population of anatomies in a minimum distance sense. Variation of several one-, two- and three-dimensional manifolds, i.e. sulci, surfaces and brain volumes are examined via Gaussian measures with mean and covariances estimated directly from maps of templates to targets. Methods are presented for estimating the covariances of vector fields from a family of empirically generated maps, posed as generalized spectrum estimation indexed over the submanifolds. Covariance estimation is made parametric, analogous to autoregressive modelling, by introducing small deformation linear operators for constraining the spectrum of the fields.     

E-Knowledge Management Framework for Government Organizations

This article aims to define a framework for establishing and sustaining a knowledge management initiative in a government setup. Recognizing the importance of managing knowledge in the emerging E-governance era, the article then presents the framework. While defining the framework, the authors draw heavily from their long professional association with government departments and the experience gleaned while implementing a similar initiative at the National Informatics Centre, Department of Information Technology, Government of India.     

Stimulation of tyrosine phosphorylation after ligation of beta7 and beta1 integrins on human B cells

B lymphocytes express several members of the integrin family of adhesion molecules that mediate cell-cell and cell-extracellular matrix interactions. In addition to beta1 integrins, predominantly alpha4 beta1, mature B cells also express alpha4 beta7, which is a receptor for vascular cell adhesion molecule-1 and fibronectin, and is also involved in the homing of B cells to mucosal sites through binding to a third ligand, mucosal address in cell adhesion molecule-1. Here we describe that crosslinking of alpha4 beta7 integrins on B cell lines and normal tonsillar B cells, induces tyrosine phosphorylation of multiple substrates of 105-130 kD, indicating that beta7 integrin plays a role as signaling molecule in B cells. This pattern of phosphorylated proteins was very similar to that induced following ligation of alpha4 beta1. Interestingly, ligation of alpha5 beta1 or alpha6 beta1 also stimulated the 105-125 kD group of phosphorylated proteins, whereas ligation of beta2 integrins did not. The focal adhesion tyrosine kinase p125FAK was identified as one of these substrates. Beta1 or beta7 mediated tyrosine phosphorylations were markedly decreased when the microfilament assembly was inhibited by cytochalasin B. These results suggest that intracellular signals initiated by different integrins in B cells may converge, to similar cytoskeleton-dependent tyrosine phosphorylated proteins.     

Reachable set of bilinear control systems with time varying drift

In this article, we give a complete characterization of the reachable set at all times for a class of bilinear control systems with time varying drift and unbounded control amplitude. These results are of fundamental interest in geometric control theory and have important applications to control of coupled spins in solid state NMR spectroscopy.