Transport and diffusion in the embedding map

We study the transport properties of passive inertial particles in a $2-d$ incompressible flows. Here the particle dynamics is represented by the $4-d$ dissipative embedding map of $2-d$ area-preserving standard map which models the incompressible flow. The system is a model for impurity dynamics in a fluid and is characterized by two parameters, the inertia parameter $\alpha$, and the dissipation parameter $\gamma$. We obtain the statistical characterisers of transport for this system in these dynamical regimes. These are, the recurrence time statistics, the diffusion constant, and the distribution of jump lengths. The recurrence time distribution shows a power law tail in the dynamical regimes where there is preferential concentration of particles in sticky regions of the phase space, and an exponential decay in mixing regimes. The diffusion constant shows behaviour of three types - normal, subdiffusive and superdiffusive, depending on the parameter regimes. Phase diagrams of the system are constructed to differentiate different types of diffusion behaviour, as well as the behaviour of the absolute drift. We correlate the dynamical regimes seen for the system at different parameter values with the transport properties observed at these regimes, and in the behaviour of the transients. This system also shows the existence of a crisis and unstable dimension variability at certain parameter values. The signature of the unstable dimension variability is seen in the statistical characterisers of transport. We discuss the implications of our results for realistic systems.Comment: 28 pages, 14 figures, To Appear in Phys. Rev. E; Vol. 79 (2009

Psychiatric Morbidity in Patients with Lower Limb Long Bone Fracture

Abstrac

Effect of hydrogen on ground state structures of small silicon clusters

We present results for ground state structures of small Si$_{n}$H (2 \leq \emph{n} \leq 10) clusters using the Car-Parrinello molecular dynamics. In particular, we focus on how the addition of a hydrogen atom affects the ground state geometry, total energy and the first excited electronic level gap of an Si$_{n}$ cluster. We discuss the nature of bonding of hydrogen in these clusters. We find that hydrogen bonds with two silicon atoms only in Si$_{2}$H, Si$_{3}$H and Si$_{5}$H clusters, while in other clusters (i.e. Si$_{4}$H, Si$_{6}$H, Si$_{7}$H, Si$_{8}$H, Si$_{9}$H and Si$_{10}$H) hydrogen is bonded to only one silicon atom. Also in the case of a compact and closed silicon cluster hydrogen bonds to the cluster from outside. We find that the first excited electronic level gap of Si$_{n}$ and Si$_{n}$H fluctuates as a function of size and this may provide a first principles basis for the short-range potential fluctuations in hydrogenated amorphous silicon. Our results show that the addition of a single hydrogen can cause large changes in the electronic structure of a silicon cluster, though the geometry is not much affected. Our calculation of the lowest energy fragmentation products of Si$_{n}$H clusters shows that hydrogen is easily removed from Si$_{n}$H clusters.Comment: one latex file named script.tex including table and figure caption. Six postscript figure files. figure_1a.ps and figure_1b.ps are files representing Fig. 1 in the main tex

Predictors of Retention among Men Attending STI Clinics in HIV Prevention Programs and Research: A Case Control Study in Pune, India

Retention is critical in HIV prevention programs and clinical research. We studied retention in the three modeled scenarios of primary prevention programs, cohort studies and clinical trials to identify predictors of retention.Men attending Sexually Transmitted Infection (STI) clinics (n = 10, 801) were followed in a cohort study spanning over a ten year period (1993-2002) in Pune, India. Using pre-set definitions, cases with optimal retention in prevention program (n = 1286), cohort study (n = 940) and clinical trial (n = 896) were identified from this cohort. Equal number of controls matched for age and period of enrollment were selected. A case control analysis using conditional logistic regression was performed. Being employed was a predictor of lower retention in all the three modeled scenarios. Presence of genital ulcer disease (GUD), history of commercial sex work and living away from the family were predictors of lower retention in primary prevention, cohort study and clinical trial models respectively. Alcohol consumption predicted lower retention in cohort study and clinical trial models. Married monogamous men were less likely to be retained in the primary prevention and cohort study models.Predicting potential drop-outs among the beneficiaries or research participants at entry point in the prevention programs and research respectively is possible. Suitable interventions might help in optimizing retention. Customized counseling to prepare the clients properly may help in their retention

Inclusive Urbanisation and Cities in the Twenty-First Century

In academic and policy discourse, urbanisation and cities are currently receiving a great deal of attention, and rightly so. Both have been central to the enormous transformation the world has been going through during the past few centuries. Many parts of the world have experienced and are experiencing an urban transformation. While these processes have taken distinct regional forms across Latin America, East and South Asia, and Africa, it is clear that, globally, the urban transformation has coincided with major societal and ecological changes. Some of these developments have been heralded as progress – notably millions of people being lifted out of poverty – while others, such as entrenching inequalities and accelerating climate change, are alarming. In recent years the pro-urban voices have been louder, but accounts of the wonders of cities need to be balanced with a recognition of the violence, inequity and environmentally destructive forces that cities can embody and reproduce. Equally important is to explore how cities and urbanisation can be made to contribute more to human wellbeing and to international and local development goals. This report is particularly concerned with whether and under what conditions more inclusive urbanisation and cities can support these development goals.UK Department for International Developmen

Evidence for directed percolation universality at the onset of spatiotemporal intermittency in coupled circle maps

We consider a lattice of coupled circle maps, a model arising naturally in descriptions of solid state phenomena such as Josephson junction arrays. We find that the onset of spatiotemporal intermittency (STI) in this system is analogous to directed percolation (DP), with the transition being to an unique absorbing state for low nonlinearities, and to weakly chaotic absorbing states for high nonlinearities. We find that the complete set of static exponents and spreading exponents at all critical points match those of DP very convincingly. Further, hyperscaling relations are fulfilled, leading to independent controls and consistency checks of the values of all the critical exponents. These results lend strong support to the conjecture that the onset of STI in deterministic models belongs to the DP universality class.Comment: Submitted to Physical Review

Coupled Maps on Trees

We study coupled maps on a Cayley tree, with local (nearest-neighbor) interactions, and with a variety of boundary conditions. The homogeneous state (where every lattice site has the same value) and the node-synchronized state (where sites of a given generation have the same value) are both shown to occur for particular values of the parameters and coupling constants. We study the stability of these states and their domains of attraction. As the number of sites that become synchronized is much higher compared to that on a regular lattice, control is easier to effect. A general procedure is given to deduce the eigenvalue spectrum for these states. Perturbations of the synchronized state lead to different spatio-temporal structures. We find that a mean-field like treatment is valid on this (effectively infinite dimensional) lattice.Comment: latex file (25 pages), 4 figures included. To be published in Phys. Rev.

Prevalence of infections among 6-16 years old children attending a semi-rural school in Western Maharashtra, India

Background: Infections are an important cause of morbidity in rural India. Reports on the prevalence of infections in older childrenand their effects on growth are scarce. Objective: The objectives were to determine the prevalence of common infections among6-16 year old school-children in a semi-rural setting in Western India and to assess the influence of infections on the growth status ofthe children. Materials and Methods: This cross-sectional study was conducted in a semi-rural setting in a Zilla Parishad PrimarySchool, Karegaon, Maharashtra. 802 children (boys = 439), 6-16 years of age were assessed. Data on height, weight and infectionrelatedsymptoms reported by children (pre-tested, validated questionnaire) were collected. K-means cluster analysis was used to createthree clusters based on the severity of infections, and one-way analysis of variance with post-hoc Tukey’s multiple comparisons wasused to test the significance of differences in means of various characteristics of the subjects in three clusters. Results: 43% boys and49% girls reported symptoms of respiratory tract infections occasionally, and 28% boys and 27% girls complained of gastrointestinal(GI) infections occasionally. Children with more severe infections were more likely to be shorter and lighter; this was more marked ingirls. Conclusions: Rural school-going children (aged 6-16 years) suffer from high rates of infections, mainly upper respiratory tractinfections followed by GI tract infections

Incidence of Primary Mitochondrial Disease in Children Younger Than 2 Years Presenting With Acute Liver Failure

Background: Mitochondrial liver disease (MLD), and in particular mitochondrial DNA (mtDNA) depletion syndrome (MDS) is an important cause of acute liver failure (ALF) in infancy. Early and accurate diagnosis is important because liver transplantation (LT) is often contraindicated. It is unclear which methods are the best to diagnose MLD in the setting of ALF. Objective: The aim of the study was to determine the incidence of MLD in children younger than 2 years with ALF and the utility of routine investigations to detect MLD. Methods: Thirty-nine consecutive infants with ALF were admitted to a single unit from 2009 to 2011. All were extensively investigated using an established protocol. Genes implicated in mitochondrial DNA depletion syndrome were sequenced in all cases and tissue mtDNA copy number measured where available. Results: Five infants (17%) had genetically proven MLD: DGUOK (n ¼ 2), POLG (n ¼ 2), and MPV17 (1). Four of these died, whereas 1 recovered. Two had normal muscle mtDNA copy number and 3 had normal muscle respiratory chain enzymes. An additional 8 children had low hepatic mtDNA copy number but pathogenic mutations were not detected. One of these developed fatal multisystemic disease after LT, whereas 5 who survived remain well without evidence of multisystemic disease up to 6 years later. Magnetic resonance spectroscopy did not distinguish between those with and without MLD. Conclusions: Low liver mtDNA copy number may be a secondary phenomenon in ALF. Screening for mtDNA maintenance gene mutations may be the most efficient way to confirm MLD in ALF in the first 2 years of life

Resilience as a policy narrative: potentials and limits in the context of urban planning

The aim of this paper is to analyse the emergence of the concept of ‘urban resilience’ in the literature and to assess its potentials and limitations as an element of policy planning. Using a systematic literature review covering the period 2003–2013 and a combination of techniques derived from narrative analysis, we show that diverse views of what urban resilience means and how it is best used (as a goal or as a conceptual/analytical framework) compete in the literature. Underlying these views are various (and sometimes diverging) interpretations of what the main issues are and what forms of policies or interventions are needed to address these issues. Urban planners need to be better aware of these different interpretations if they want to be in a position to use resilience appropriately and spell out what resilience can bring to their work. The review also highlights that the notion of urban resilience often lacks adequate acknowledgement of the political economy of urbanization and consequently does not challenge the status quo which, some argue, is socially unjust and environmentally unsustainable. As such it runs the risk to be seen as simply making marginalized urban communities more resilient to the shocks and inequity created by the current dominant paradigm