Content analysis of children's programs on Boston's television stations

Thesis (Ed.M.)--Boston Universit

Scalability study of parallel spatial direct numerical simulation code on IBM SP1 parallel supercomputer

The implementation and the performance of a parallel spatial direct numerical simulation (PSDNS) code are reported for the IBM SP1 supercomputer. The spatially evolving disturbances that are associated with laminar-to-turbulent in three-dimensional boundary-layer flows are computed with the PS-DNS code. By remapping the distributed data structure during the course of the calculation, optimized serial library routines can be utilized that substantially increase the computational performance. Although the remapping incurs a high communication penalty, the parallel efficiency of the code remains above 40% for all performed calculations. By using appropriate compile options and optimized library routines, the serial code achieves 52-56 Mflops on a single node of the SP1 (45% of theoretical peak performance). The actual performance of the PSDNS code on the SP1 is evaluated with a 'real world' simulation that consists of 1.7 million grid points. One time step of this simulation is calculated on eight nodes of the SP1 in the same time as required by a Cray Y/MP for the same simulation. The scalability information provides estimated computational costs that match the actual costs relative to changes in the number of grid points

Crescimento de cinco espécies nativas em successão natural na Amazônia Oriental.

Na Amazônia Legal brasileira, mandioca (Manihot esculenta) é uma colheita principal para populações rurais cuja produção é feita através de agricultura iniciada com queimada. Sistemas agroflorestais de corte e trituração estão sendo implementados na Amazônia Legal para substituir o fogo em sistemas de produção. Em abril de 2005, um hectare de floresta secundária de sete anos de idade foi derrubado usando um tractor TRITUCAP do Projeto Tipitamba para preparar o terreno para o projeto no campus de pesquisa de UFRA em Igarapé Açu, Pará, Brasil. Um sistema agroflorestal foi implementado em todas as parcelas usando espécies de árvores nativas em plantio misto com M. esculenta. A pesquisa foi analisada utilizando um fatorial duplo com duas parcelas-principais (com ou sem adubo P e K) e dois tratamentos parcelas-secundárias (com ou sem a espécie fixadora de N2, Inga edulis). As árvores, mandioca, competição, capa orgânica e solo foram medidos após 1 e 2 anos. Depois de vinte meses de cultura mista, M. esculenta foi colhida e a parcela se deixou à sucessão natural. Depois de 4 anos de crescimento de vegetação secundaria, ou 6 anos após plantio, as árvores plantadas foram medidas em altura, DAP e DAB. Adubação com P e K diminuiu a sobrevivência de todas as espécies, menos P. multijuga, mas a presença de I. edulis não teve efeito. Adubação com P e K aumentou o crescimento de todas as espécies depois de 6 anos mas a presença de I. edulis nao apresentou efeito significativo no crescimento das árvores.Editores técnicos: Roberto Porro, Milton Kanashiro, Maria do Socorro Gonçalves Ferreira, Leila Sobral Sampaio e Gladys Ferreira de Sousa

Ground state properties of a confined simple atom by C60_{60} fullerene

We numerically study the ground state properties of endohedrally confined hydrogen (H) or helium (He) atom by a molecule of C$_{60}$. Our study is based on Diffusion Monte Carlo method. We calculate the effects of centered and small off-centered H- or He-atom on the ground state properties of the systems and describe the variation of ground state energies due to the C$_{60}$ parameters and the confined atomic nuclei positions. Finally, we calculate the electron distributions in $x-z$ plane in a wide range of C$_{60}$ parameters.Comment: 23 pages, 9 figures. To appear in J.Phys. B: Atom. Mol. Op

Tbx20 Is Required in Mid-Gestation Cardiomyocytes and Plays a Central Role in Atrial Development.

RationaleMutations in the transcription factor TBX20 (T-box 20) are associated with congenital heart disease. Germline ablation of Tbx20 results in abnormal heart development and embryonic lethality by embryonic day 9.5. Because Tbx20 is expressed in multiple cell lineages required for myocardial development, including pharyngeal endoderm, cardiogenic mesoderm, endocardium, and myocardium, the cell type-specific requirement for TBX20 in early myocardial development remains to be explored.ObjectiveHere, we investigated roles of TBX20 in midgestation cardiomyocytes for heart development.Methods and resultsAblation of Tbx20 from developing cardiomyocytes using a doxycycline inducible cTnTCre transgene led to embryonic lethality. The circumference of developing ventricular and atrial chambers, and in particular that of prospective left atrium, was significantly reduced in Tbx20 conditional knockout mutants. Cell cycle analysis demonstrated reduced proliferation of Tbx20 mutant cardiomyocytes and their arrest at the G1-S phase transition. Genome-wide transcriptome analysis of mutant cardiomyocytes revealed differential expression of multiple genes critical for cell cycle regulation. Moreover, atrial and ventricular gene programs seemed to be aberrantly regulated. Putative direct TBX20 targets were identified using TBX20 ChIP-Seq (chromatin immunoprecipitation with high throughput sequencing) from embryonic heart and included key cell cycle genes and atrial and ventricular specific genes. Notably, TBX20 bound a conserved enhancer for a gene key to atrial development and identity, COUP-TFII/Nr2f2 (chicken ovalbumin upstream promoter transcription factor 2/nuclear receptor subfamily 2, group F, member 2). This enhancer interacted with the NR2F2 promoter in human cardiomyocytes and conferred atrial specific gene expression in a transgenic mouse in a TBX20-dependent manner.ConclusionsMyocardial TBX20 directly regulates a subset of genes required for fetal cardiomyocyte proliferation, including those required for the G1-S transition. TBX20 also directly downregulates progenitor-specific genes and, in addition to regulating genes that specify chamber versus nonchamber myocardium, directly activates genes required for establishment or maintenance of atrial and ventricular identity. TBX20 plays a previously unappreciated key role in atrial development through direct regulation of an evolutionarily conserved COUPT-FII enhancer

Active Control of Boundary-Layer Instabilities: Use of Sensors and Spectral Controller

Full Navier-Stokes equations were conducted to determine the feasibility of automating the control of wave instabilities within a flat plate boundary layer with sensors, actuators, and a spectral controller. The results indicate that a measure of wave cancellation can be obtained for small and large amplitude instabilities without feedback; however, feedback is required to optimize the control amplitude and phase for exact wave cancellation

Five native tree species and manioc under slash-and-mulch agroforestry in the eastern Amazon of Brazil: plant growth and soil responses.

Throughout the Amazon of Brazil, manioc (Manihot esculenta) is a staple crop produced through slash-and-burn agriculture. Nutrient losses during slash-and-burn can be large and nutrient demand by food crops so great that ?elds are often abandoned after two years. In recent decades, farmers have reduced the fallow phase from 20 to *5 years, limiting plant nutrient accumulation to sustain crop yields. Improved fallows through simultaneous planting of trees with food crops may accelerate nutrient re-accumulation. In addition, slash-and-mulch technology may prevent loss of nutrients due to burning and mulch decomposition may serve as a slow-release source of nutrients. This study in Para´, Brazil, in a 7-year-old secondary forest following slashing and mulching of the vegetation, involved two main plot treatments (with and without P and K fertilizers) and two sub-plot treatments (with or without a N2-?xer Inga edulis). A mixed-culture of trees and manioc was planted in all plots. P and K fertilizer increased tree mortality due to weed competition but growth of surviving trees in four of the ?ve tree species tested also increased as did biomass production of manioc. In the N2-?xer treatment trends of greater growth and survival of four of ?ve tree species and manioc biomass were also observed. Fertilization increased the biomass of competing vegetation, but there was a fertilizer by N2 -?xer interaction as I. edulis caused a reduction in competing biomass in the fertilized treatment. After one year, fertilization increased decomposition of the mulch such that Ca, Mg, and N contents within the mulch all decreased. In contrast, P and K contents of mulch increased in all treatments. No in?uence of the N2 -?xer on 0–10 cm soil N contents was observed. Two years after establishment, this agroforestry system succeeded in growing a manioc crop and leaving a well-maintained tree fallow after the crop harvest

Bostonia. Volume 3

Founded in 1900, Bostonia magazine is Boston University's main alumni publication, which covers alumni and student life, as well as university activities, events, and programs

A self-contained, automated methodology for optimal flow control validated for transition delay

This paper describes a self-contained, automated methodology for flow control along with a validation of the methodology for the problem of boundary layer instability suppression. The objective of control is to match the stress vector along a portion of the boundary to a given vector; instability suppression is achieved by choosing the given vector to be that of a steady base flow, e.g., Blasius boundary layer. Control is effected through the injection or suction of fluid through a single orifice on the boundary. The present approach couples the time-dependent Navier-Stokes system with an adjoint Navier-Stokes system and optimality conditions from which optimal states, i.e., unsteady flow fields, and control, e.g., actuators, may be determined. The results demonstrate that instability suppression can be achieved without any a priori knowledge of the disturbance, which is significant because other control techniques have required some knowledge of the flow unsteadiness such as frequencies, instability type, etc