The anthropogenic impact of railway operation on the flora diversity on rail embankment in two stations, Delta State, Nigeria

This study was carried out with the aim of anticipating the effects of anthropogenic activities on the plant species flora on railway embankment in Urhuovie-Abraka and Ujevwu-Warri train stations in Delta State, Nigeria. Quadrat sampling method using line transect was adopted for the collection of plant species along the designated embankment of the rail track. Twelve (12) plant species were encountered and documented within the designated rail track at Ujevwu train station, Warri. The species of plant encountered in the railway station cut across six (6) different families including Poaceae as the most dominant family with four (4) representative species, followed by Fabaceae which had three (3) species. Asteraceae family was represented by two (2) species while Cyperaceae, Malvaceae and Plantaginaceae families were represented by single species whereas in Urhuovie-Abraka train station, A total of ten (10) plant species were encountered which cut across five (5) different families including Asteraceae (2), Convolvulaceae (1), Fabaceae (4), Malvaceae (1) and Poaceae (2). Ujevwu-Warri rail track had more plant species (12) than that of Urhuovie-Abraka station (10). Activities around these rail tracks included open cattle grazing, emerging human communities and periodic cutting of plant species to prevent the plant species encroaching into the rail track which could hinder the smooth operation of the railway system

Real-time human action recognition on an embedded, reconfigurable video processing architecture

Copyright @ 2008 Springer-Verlag.In recent years, automatic human motion recognition has been widely researched within the computer vision and image processing communities. Here we propose a real-time embedded vision solution for human motion recognition implemented on a ubiquitous device. There are three main contributions in this paper. Firstly, we have developed a fast human motion recognition system with simple motion features and a linear Support Vector Machine (SVM) classifier. The method has been tested on a large, public human action dataset and achieved competitive performance for the temporal template (eg. “motion history image”) class of approaches. Secondly, we have developed a reconfigurable, FPGA based video processing architecture. One advantage of this architecture is that the system processing performance can be reconfiured for a particular application, with the addition of new or replicated processing cores. Finally, we have successfully implemented a human motion recognition system on this reconfigurable architecture. With a small number of human actions (hand gestures), this stand-alone system is performing reliably, with an 80% average recognition rate using limited training data. This type of system has applications in security systems, man-machine communications and intelligent environments.DTI and Broadcom Ltd

Automatic structures, rational growth and geometrically finite hyperbolic groups

We show that the set $SA(G)$ of equivalence classes of synchronously automatic structures on a geometrically finite hyperbolic group $G$ is dense in the product of the sets $SA(P)$ over all maximal parabolic subgroups $P$. The set $BSA(G)$ of equivalence classes of biautomatic structures on $G$ is isomorphic to the product of the sets $BSA(P)$ over the cusps (conjugacy classes of maximal parabolic subgroups) of $G$. Each maximal parabolic $P$ is a virtually abelian group, so $SA(P)$ and $BSA(P)$ were computed in ``Equivalent automatic structures and their boundaries'' by M.Shapiro and W.Neumann, Intern. J. of Alg. Comp. 2 (1992) We show that any geometrically finite hyperbolic group has a generating set for which the full language of geodesics for $G$ is regular. Moreover, the growth function of $G$ with respect to this generating set is rational. We also determine which automatic structures on such a group are equivalent to geodesic ones. Not all are, though all biautomatic structures are.Comment: Plain Tex, 26 pages, no figure

Phenomenology of V_ub from Ratios of Inclusive B Decay Rates

We explore the theoretical feasibility of extracting V_ub from two ratios built from B meson inclusive partial decays, R_1 = Gamma(b-> u cbar s)/3Gamma(b -> c l nu), and R_2 = [Gamma(b -> c X) - Gamma(b -> cbar X)]/Gamma(b -> c ubar d). We discuss contributions to these quantities from perturbative and nonperturbative physics, and show that they can be computed with overall uncertainties at the level of 10%.Comment: 19 pages, 8 embedded EPS figures, uses REVTe

Influence of co - and counter-propagating light on the phase-mismatch effect in semiconductor optical amplifiers

peer-reviewedThe phase-mismatch effect, caused by the difference in confinement factor between transverse electric (TE) and transverse magnetic (TM) modes, has not been observed in semiconductor optical amplifiers (SOAs) and is not typically accounted for. In this work, we investigate the characteristics of the phase-mismatch four wave mixing (FWM) effect, which occurs in SOA devices. Our results reveal a sinc-like response in the intensity of co- and counter-FWM conjugates as a function of the detuning shift between interacting beams. It is demonstrated that the coherence lengths between the phase match/mismatch cycles differ between co- and counter-propagating nondegenerate FWM experiments and depend on the amplified TE/TM polarizations of interacting waves aligned with respect to the birefringent axes of SOAs. The coherence lengths between each phase match/mismatch cycle in co-propagation experiments are found to be 1600 and infinite GHz, respectively, compared to 800 and 400 GHz found in counter-propagation experiments.ACCEPTEDpeer-reviewe

Design and realization of a miniature capacitive silicon force sensor for loads up to 500 kg

In this paper, a micromachined silicon load cell (force sensor) is presented for measuring loads up to 500 kg. The load cell has been realized and tested. Measurement results show a hysteresis error of ±0.02 % of full-scale. Creep at 500 kg after 30 minutes is within 0.01 %. These measurements show that the performance has improved by a factor of 10 compared to the previous design

B decay shape variables and the precision determination of |Vcb| and mb

We present expressions for shape variables of B decay distributions in several different mass schemes, to order $\alpha_s^2\beta_0$ and (Lambda_{QCD}/mb)^3. Such observables are sensitive to the b quark mass and matrix elements in the heavy quark effective theory, and recent measurements allow precision determinations of some of these parameters. We perform a combined fit to recent experimental results from CLEO, BABAR, and DELPHI, and discuss the theoretical uncertainties due to nonperturbative and perturbative effects. We discuss the possible discrepancy between the OPE prediction, recent BABAR results and the measured branching fraction to D and D* states. We find |Vcb| = (40.8 +- 0.9) x 10^{-3} and mb^{1S} = 4.74 +- 0.10 GeV, where the errors are dominated by experimental uncertainties.Comment: 23 pages, 3 figures, Version to appear in PR

A Gaussian Theory of Superfluid--Bose-Glass Phase Transition

We show that gaussian quantum fluctuations, even if infinitesimal, are sufficient to destroy the superfluidity of a disordered boson system in 1D and 2D. The critical disorder is thus finite no matter how small the repulsion is between particles. Within the gaussian approximation, we study the nature of the elementary excitations, including their density of states and mobility edge transition. We give the gaussian exponent $\eta$ at criticality in 1D and show that its ratio to $\eta$ of the pure system is universal.Comment: Revtex 3.0, 11 pages (4 figures will be sent through airmail upon request

An Australian twin study of cannabis and other illicit drug use and misuse, and other psychopathology

Cannabis is the most widely used illicit drug throughout the developed world and there is consistent evidence of heritable influences on multiple stages of cannabis involvement including initiation of use and abuse/dependence. In this paper, we describe the methodology and preliminary results of a large-scale interview study of 3,824 young adult twins (born 1972–1979) and their siblings. Cannabis use was common with 75.2% of males and 64.7% of females reporting some lifetime use of cannabis while 24.5% of males and 11.8% of females reported meeting criteria for DSM-IV cannabis abuse or dependence. Rates of other drug use disorders and common psychiatric conditions were highly correlated with extent of cannabis involvement and there was consistent evidence of heritable influences across a range of cannabis phenotypes including early (≤15 years) opportunity to use (h(2) = 72%), early (≤16 years) onset use (h(2) = 80%), using cannabis 11+ times lifetime (h(2) = 76%), and DSM abuse/dependence (h(2) = 72%). Early age of onset of cannabis use was strongly associated with increased rates of subsequent use of other illicit drugs and with illicit drug abuse/dependence; further analyses indicating that some component of this association may have been mediated by increasing exposure to and opportunity to use other illicit drugs