Nucleon electromagnetic form factors in a quark-gluon core model

We study the nucleon electromagnetic form factors in a quark-gluon core model framework, which can be viewed as an extension of the Isgur-Karl model of baryons. Using this picture we derive nucleon electromagnetic dipole form factors at low Q^2 and the deviation from the dipole form at high Q^2, that are consistent with the existing experimental data.Comment: 5 pages, 3 figure

Active Brownian Particles. From Individual to Collective Stochastic Dynamics

We review theoretical models of individual motility as well as collective dynamics and pattern formation of active particles. We focus on simple models of active dynamics with a particular emphasis on nonlinear and stochastic dynamics of such self-propelled entities in the framework of statistical mechanics. Examples of such active units in complex physico-chemical and biological systems are chemically powered nano-rods, localized patterns in reaction-diffusion system, motile cells or macroscopic animals. Based on the description of individual motion of point-like active particles by stochastic differential equations, we discuss different velocity-dependent friction functions, the impact of various types of fluctuations and calculate characteristic observables such as stationary velocity distributions or diffusion coefficients. Finally, we consider not only the free and confined individual active dynamics but also different types of interaction between active particles. The resulting collective dynamical behavior of large assemblies and aggregates of active units is discussed and an overview over some recent results on spatiotemporal pattern formation in such systems is given.Comment: 161 pages, Review, Eur Phys J Special-Topics, accepte

Tree loss impacts on ecological connectivity: Developing models for assessment

Trees along linear features are important landscape features, and their loss threatens ecological connectivity. Until recently, trees outside of woodlands (TOWs) were largely unmapped however; the development of innovation mapping techniques provides opportunities to understand the distribution of such trees and to apply spatially explicit models to explore the importance of trees for connectivity. In this study, we demonstrate the utility of models when investigating tree loss and impacts on connectivity. Specifically, we investigated the consequences of tree loss due to the removal of roadside trees, a common management response for diseased or damaged trees, on wider landscape functional connectivity. We simulated the loss of roadside trees within six focal areas of the south east of the UK. We used a spatially explicit individual-based modelling platform, RangeShifter, to model the movement of 81 hypothetical actively dispersing woodland breeding species across these agriculturally fragmented landscapes. We investigated the extent to which removal of trees, from roadsides within the wider landscape, affected the total number of successful dispersers in any given year and the number of breeding woodlands that became isolated through time. On average roadside trees accounted for < 2% of land cover, but removing 60% of them (~ 1.2% of land cover) nevertheless decreased the number of successful dispersers by up to 17%. The impact was greatest when roadside trees represented a greater proportion of canopy cover. The study therefore demonstrates that models such as RangeShifter can provide valuable tools for assessing the consequences of losing trees outside of woodlands

Investing in China: guidelines for success

This article seeks to investigate the success of China's open door policy and the part of U.K. corporations within it. By recounting organizational experiences, it hopes to provide some indications of best practice to be adopted in formulating and implementing strategies for penetrating the Chinese market

Interobserver variability in assessment of cranial ultrasound in very preterm infants

BACKGROUND: Cranial ultrasound (cUS) findings help doctors in the clinical management of preterm infants and in their discussion with parents regarding prediction of outcome. cUS is often used as outcome measure in clinical research studies. Accurate cUS performance and interpretation is therefore required. AIMS: The aims of this study were (i) to assess the interobserver variability in cUS interpretation, and (ii) to evaluate whether level of cUS expertise influences the interobserver variability. METHODS: Fifty-eight cUS image series of preterm infants born below 32weeks of gestation collected within the Swiss Neonatal Network were sent to 27 observers for reviewing. Observers were grouped into radiologists, experienced neonatologists and less experienced neonatologists. Agreement between observers was calculated using Kappa statistics. RESULTS: When cystic periventricular leukomalacia, intraventricular haemorrhage and periventricular haemorrhagic infarction were combined to one outcome, agreement among all observers was moderate. When divided into subgroups, kappa for the combined outcome was 0.7 for experienced neonatologists, 0.67 for radiologists and 0.53 for inexperienced neonatologists. Marked difference in interobserver agreement between experienced neonatologists and radiologists could be found for haemorrhagic periventricular ifraction (HPI). CONCLUSIONS: Our results suggest that interobserver agreement for interpretation of cUS varies from poor to good varying with the type of abnormality and level of expertise, suggesting that widespread structured training should be made available to improve the performance and interpretation of cUS