Pre-logarithmic and logarithmic fields in a sandpile model

We consider the unoriented two-dimensional Abelian sandpile model on the half-plane with open and closed boundary conditions, and relate it to the boundary logarithmic conformal field theory with central charge c=-2. Building on previous results, we first perform a complementary lattice analysis of the operator effecting the change of boundary condition between open and closed, which confirms that this operator is a weight -1/8 boundary primary field, whose fusion agrees with lattice calculations. We then consider the operators corresponding to the unit height variable and to a mass insertion at an isolated site of the upper half plane and compute their one-point functions in presence of a boundary containing the two kinds of boundary conditions. We show that the scaling limit of the mass insertion operator is a weight zero logarithmic field.Comment: 18 pages, 9 figures. v2: minor corrections + added appendi

Hypersonic laminar boundary layers around slender bodies

Compressible laminar boundary layer equations considered for hypersonic flow around slender bodie

Abelian Sandpile Model: a Conformal Field Theory Point of View

In this paper we derive the scaling fields in $c=-2$ conformal field theory associated with weakly allowed clusters in abelian sandpile model and show a direct relation between the two models.Comment: 9 pages, 2 figure

Determinants Of Early Childbearing Among Young Female Adults In The Gambia

This thesis examines the determinants of childbearing among young Gambian women aged 13 to 24 and ranks the respective components (or groups of variables) in order of importance. An empirical analysis is done using bivariate and multi-variate statistical techniques. Based on these analyses, it is found that the factors of the empirical model (combining the reference group theory and a Bongaarts-type framework) vary in their effect on the fertility of young women. The most important of the socioeconomic, demographic and cultural (SEDC) variables are educational attainment, employment status, looking for work, area of residence, age, number of siblings, rank of siblings, number of desired children, and religion.;However, it is an important finding of this thesis that fertility is higher among young women in urban than non-urban areas in The Gambia. This is in contrast with earlier findings that fertility level tend to be higher in rural than urban areas. Although this finding is unexpected, it is not implausible. It can be attributed to changes in the behavioural and sociocultural profile of young Gambian women, as well as improvements in nutritional levels, better medical and health conditions, and developments in reproductive technology.;Also, it is clear from this thesis that childbearing is influenced by both knowledge of contraception and reproductive health as well as opinions and beliefs about relationships, sex, and marriage. Practices such as the sexual activity of friends and attendance of educational programmes affect childbearing as well. Yet, these KAP variables can affect fertility only through the proximate determinants which have direct effects.;Except for age at first menstruation which serves as proxy for biological maturity of girls, all of the proximate determinants have been found to be important in predicting early childbearing. As for the outcome of ranking the major components of the model in order of importance, the proximate determinants are found to be more influential than the other major components that indirectly affect early childbearing. Also, the socioeconomic, demographic and cultural (SEDC) variables are more important than those of knowledge, attitude and practice (KAP). The thesis concludes with suggestions for future research and a review of policies and programmes of relevance in The Gambian context

Quantum critical fluctuations in disordered d-wave superconductors

Quasiparticles in the cuprates appear to be subject to anomalously strong inelastic damping mechanisms. To explain the phenomenon, Sachdev and collaborators recently proposed to couple the system to a critically fluctuating order parameter mode of either id_{xy}- or is-symmetry. Motivated by the observation that the energies relevant for the dynamics of this mode are comparable to the scattering rate induced by even moderate impurity concentrations, we here generalize the approach to the presence of static disorder. In the id-case, we find that the coupling to disorder renders the order parameter dynamics diffusive but otherwise leaves much of the phenomenology observed in the clean case intact. In contrast, the interplay of impurity scattering and order parameter fluctuations of is-symmetry entails the formation of a secondary superconductor transition, with a critical temperature exponentially sensitive to the disorder concentration.Comment: 4 pages, 2 figures include

Higher Order and boundary Scaling Fields in the Abelian Sandpile Model

The Abelian Sandpile Model (ASM) is a paradigm of self-organized criticality (SOC) which is related to $c=-2$ conformal field theory. The conformal fields corresponding to some height clusters have been suggested before. Here we derive the first corrections to such fields, in a field theoretical approach, when the lattice parameter is non-vanishing and consider them in the presence of a boundary.Comment: 7 pages, no figure

Changing communication on researchgate through interface updates

Informal scholarly communication across the Web is a growing component of the scholarly communication infrastructure. This study describes the effects of three different interfaces on these informal channels. Interface design has a widely studied effect on user behavior, and new users often encounter barriers during accessing social media tools. Using a mixed methods approach, we collected and grouped 413 posts across three distinct interfaces of ResearchGate's communication platform. Our results show that scholars were more polite in the initial group discussion interface but that user interface design did not change the core communication patterns of sharing information and opinions among scholars. The site also transitioned from one-to-many discussions to one-to-one posts, but new users were generally welcomed to the scholarly communications

Effects of Paclobutrazol and its method of application on the growth and transpiration of Acacia Mangium Seedlings

Ten-week-old potted A. mangium seedlings were subjected to a growth retardant, paclobutrazol (PP333), at concentrations of 0, 0.5, 1, 4 and 12 gil. Four methods of application were tested namely S, soil drenching at week 0; F1, foliar spray (potting soil protected from chemical) at week 0; F2, foliar spray (potting soil protected from chemical) at week 0 and 6; and S+F, soil and foliar spray (potting soil exposed to chemical spray) at week O. Plants were harvested after 12 weeks for various growth measurements. Height and leaf area increments, transpiration and stomatal conductance were monitored at weekly intervals. Paclobutrazol was found to be effective in reducing root and shoot growth, transpiration and stomatal conductance of the seedlings. Treated plants had higher root to shoot ratios. The effects of the chemical increased with increasing concentration and frequency of application for the foliar spray. The chemical was most effective when applied through the soil either l7y drenching (S) or soil and foliar spray (S+F)

Comparison of Scale Identification Methods in Mixture IRT Models

The effects of three scale identification constraints in mixture IRT models were studied. A simulation study found no constraint effect on the mixture Rasch and mixture 2PL models, but the item anchoring constraint was the only one that worked well on selecting correct model with the mixture 3PL model