Kinky Brane Worlds

We present a toy model for five-dimensional heterotic M-theory where bulk three-branes, originating in 11 dimensions from M five-branes, are modelled as kink solutions of a bulk scalar field theory. It is shown that the vacua of this defect model correspond to a class of topologically distinct M-theory compactifications. Topology change can then be analysed by studying the time evolution of the defect model. In the context of a four-dimensional effective theory, we study in detail the simplest such process, that is the time evolution of a kink and its collision with a boundary. We find that the kink is generically absorbed by the boundary thereby changing the boundary charge. This opens up the possibility of exploring the relation between more complicated defect configurations and the topology of brane-world models.Comment: 31 pages, Latex, 6 eps-figure

PARENTAL WARMTH AND PHYSICAL PUNISHMENT AND THEIR ASSOCIATIONS WITH CHILDREN’S SOCIAL AND ACADEMIC SKILLS IN TRINIDAD AND TOBAGO

Using the major tenets of interpersonal acceptance-rejection theory (IPARTheory), Baumrind’sparenting styles typologies and the Developmental Niche Model as guides, this study examined the moderating role of parental warmth on the associations between severity and fairness of physical punishment and preschool-aged children’s social and academic skills in families in the twin-island Caribbean nation of Trinidad and Tobago. The sample consisted of 191 mothers and 179 fathers, and their preschool-aged children from four diverse ethnic and socioeconomic communities. Mothers and fathers filled out a socio-demographic questionnaire, the parental acceptance-rejection questionnaire (PARQ-Short-Form), and the physical punishment questionnaire (PPQ). Teachers provided assessments of children’s early academic skills using the Child Development Index Card. Teachers also assessed children’s social skills by completing the Child Rating Questionnaire. Three questions were examined: (a) Do mothers and fathers differ in the use of different modes of physical punishment with boys and girls?(b) Does maternal warmth moderate the associations between maternal assessments of severity and fairness of physical punishment and children’s early social and academic skills? And, (c) Does paternal warmth moderate the associations between paternal assessments of severity and fairness of physical punishment and children’s early social and academic skills? Results indicate that mothers were more likely to slap, pull, and pinch children than fathers. Mothers and fathers did not differ in their use of different modes of physical punishment with boys and girls. There were no significant direct associations between paternal and maternal assessments of severity and fairness of punishment and children’s social and academic skills. Paternal and maternal warmth did not moderate the associations between paternal and maternal assessments of severity and fairness of punishment and children’s social and academic skills. Findings are discussed within the context of a children’s rights perspective

Tree-Based Radiative Transfer of Diffuse Sources: A Novel Scheme and its Application in Massive Star Formation

Electromagnetic radiation plays an essential role in the evolution of astrophysical phenomena. Solving radiative transfer in numerical radiation hydrodynamics simulations is expensive and challenging. This work presents a novel method called \textsc{TreeRay/RadPressure} employing a tree-based backwards ray-tracing approach to compute radiative transfer of non-ionizing radiation on diffuse sources such as interstellar dust. The novel scheme allows for every computational entity to be a source of radiation and a contributor towards extinction. The scheme is implemented and tested for a finite volume method and can be generalized to work with particles of, for example, a Smoothed-Particle-Hydrodynamics method. The scheme developed in this thesis is suitable to compute radiation pressure on dust and gas. Coupled to a chemical network, the method allows to accurately model radiative cooling and heating of dust. An application of the scheme in the context of massive star formation shows that fragmentation induced by self-gravity is reduced by the scheme's more accurate teatmennt of cooling and heating. In particular, self-shielding of dust allows efficient cooling only from the surface of optically thick regions. With the help of \textsc{TreeRay/RadPressure}, the role of metallicity in the collapse of a subvirial turbulent core forming a massive stars is investigated. The core has a radius of 0.1 parsec and a mass of 150 solar masses. Along with ionizing radiation computed by \textsc{TreeRay/OnTheSpot}, the relative strength of radiation pressure and ionizing feedback are examined. Radiation pressure is the dominant feedback mechanism during the formation of the massive star while it hosts an ultra-compact HII region. Radiation pressure does not halt accretion onto the massive star and its strength is reduced once a disk establishes. Greater metallicities favour fragmentation by enhancing cooling. This results in a greater multiplicity with increased metallicity. Radiation pressure manages to launch bipolar outflows along the rotational axis of the disk. \textsc{TreeRay/RadPressure} is compared to a multi-wavelength scheme based on RADMC-3D to compute radiation pressure. The comparison is done using non-trivial density distributions generated by radiation hydrodynamics simulations with \textsc{TreeRay/RadPressure}. The comparison shows the radiation pressure calculations of both schemes to agree for the majority of density and luminosity configurations. Simplfied theoretical modelling using the optical depth as a proxy for the momentum boost fails to estimate the radiation pressure

Why Are some Filipino Children not in School?

What are the factors that contribute to the nonparticipation of children in school? Who are the ones accountable to this complicating issue? This Note identifies some factors and looks deeper into each of them.poverty, education, Philippines, carbon tax, carbon dioxide emission, school participation, out-of-school children

Some Issues on Low Participation Rates in Basic Education

Despite the various efforts to improve the Philippines` education system, why does this country still have low participation rates in education? What are the reasons behind the growing numbers of out-of-school children? What are the reasons for their nonattendance? This Note delves deeper into the issue.Philippines, basic education, school participation, out-of-school children

Volumetric SAR near-field upsampling and basebanding

Highly sampled imagery offers many benefits to the radar practitioner, ranging from easier image coregistration to simple visual appeal. However, it is often overlooked due to the computational burden forming such an image imposes. Fast image formation typically imposes restrictions on the imaging scenario, for example synthetic aperture radar (SAR) far-field, and exploits parallelism through use of modern multi- core architecture. Imposing a SAR near-field requirement on the image formation limits the applicability of several of the faster algorithms, thus there is a need to create a general process to achieve highly sampled imagery, regardless of the imaging regime. In this letter, a method for accurately upsampling near-field (SAR) imagery is presented. This is applicable to both SAR near-field and SAR far-field scenarios. The methodology is discussed, and an example is provided in the form of a SAR near-field volumetric image of a miniature tank. The limitations to the approach are discussed and prospects for future work given

Through-wall detection and imaging of a vibrating target using synthetic aperture radar

This paper explains the development of a through-wall synthetic aperture radar (SAR) simulator, which is being used to investigate the SAR artefacts originating from vibrating targets, known as paired echoes. The simulation and experimental results both show that paired echoes can be detected and imaged through a wall, with a noticeable reduction in intensity, resulting in the number of visible echoes to be reduced in brightness and appear shifted in location in a through-wall SAR image

Measurement of color flow in t-tbar events from p-pbar collisions at sqrt(s)=1.96 TeV

We present the first measurement of the color representation of the hadronically decaying W boson in t-tbar events, from 5.3 fb^-1 of integrated luminosity collected with the D0 experiment. A novel calorimeter-based vectorial variable, "jet pull," is used, sensitive to the color-flow structure of the final state. We find that the fraction of uncolored W bosons is 0.56 +- 0.42(stat+syst), in agreement with the standard model

Nuclear Parity Violation from Lattice QCD

The electroweak interaction at the level of quarks and gluons are well understood from precision measurements in high energy collider experiments. Relating these fundamental parameters to Hadronic Parity Violation in nuclei however remains an outstanding theoretical challenge. One of the most interesting observables in this respect is the parity violating hadronic neutral current: it is hard to measure in collider experiments and is thus the least constrained observable of the Standard Model. Precision measurements of parity violating transitions in nuclei can help to improve these constraints. In these systems however, the weak interaction is masked by effects of the seven orders of magnitude stronger non-perturbative strong interaction. Therefore, in order to relate experimental measurements of the parity violating pion-nucleon couplings to the fundamental Lagrangian of the SM, these non-perturbative effects have to be well understood. In this paper, we are going to present a Lattice QCD approach for computing the $\Delta I{=}2$ parity violating matrix element in proton proton scattering. This process does not involve disconnected diagrams in the isospin symmetric limit and is thus a perfect testbed for studying the feasibility of the more involved calculation of the parity violating pion-nucleon coupling.Comment: PoS Lattice 201