Sampling Trees from Evolutionary Models

A wide range of evolutionary models for species-level (and higher) diversification have been developed. These models can be used to test evolutionary hypotheses and provide comparisons with phylogenetic trees constructed from real data. To carry out these tests and comparisons, it is often necessary to sample, or simulate, trees from the evolutionary models. Sampling trees from these models is more complicated than it may appear at first glance, necessitating careful consideration and mathematical rigor. Seemingly straightforward sampling methods may produce trees that have systematically biased shapes or branch lengths. This is particularly problematic as there is no simple method for determining whether the sampled trees are appropriate. In this paper, we show why a commonly used simple sampling approach (SSA)—simulating trees forward in time until n species are first reached—should only be applied to the simplest pure birth model, the Yule model. We provide an alternative general sampling approach (GSA) that can be applied to most other models. Furthermore, we introduce the constant-rate birth-death model sampling approach, which samples trees very efficiently from a widely used class of models. We explore the bias produced by SSA and identify situations in which this bias is particularly pronounced. We show that using SSA can lead to erroneous conclusions: When using the inappropriate SSA, the variance of a gradually evolving trait does not correlate with the age of the tree; when the correct GSA is used, the trait variance correlates with tree age. The algorithms presented here are available in the Perl Bio::Phylo package, as a stand-alone program TreeSample, and in the R TreeSim packag

A New Stochastic Inner Product Core Design for Digital FIR Filters

Stochastic computing (SC) is a computational technique with computational operations governed by probability instead of arithmetic rules. It recently found promising applications in digital and image processing areas and attracted attentions of researchers. In this paper, a new stochastic inner product (multiply and accumulate) core with an improved scaling scheme is presented for improving the accuracy and fault tolerance performance of SC based finite impulse response (FIR) digital filters. The proposed inner product core is designed using tree structured multiplexers which is capable of reducing the critical path and fault propagation in the stochastic circuitry. The designed inner product core can lead to construction of SC based light weight and multiplierless FIR digital filters. As a result, an SC based FIR digital FIR filter is implemented on Altera Cyclone V FPGA which operates on stochastic sequences of 256-bits length (8-bits precision level). Experimental results show that the developed filter has lower hardware cost, better accuracy and higher fault tolerance level compared with other stochastic implementations

Yussibnosh toughened up by hardship

AS a boy, Barisan Nasional (BN) candidate for the Balingian by-­election, Yussibnosh Balo, climbed coconut trees and sold corn by the roadside. The son of a sago tree cutter would do odd jobs during weekends to make ends meet in Tellian here and walked 5km to get to his school

p300 Alters Keratinocyte Cell Growth and Differentiation through Regulation of p21Waf1/CIP1

Background: p300 functions as a transcriptional co-activator to regulate many cellular responses such as cell growth, transformation, development and differentiation. It has been shown to affect the transcriptional activity of p53 which regulates p21 Waf1/CIP1 expression, however, the role of p300 in differentiation remains unclear. Methodology and Principal Findings: Knockdown of p300 protein with short hairpin RNA (shRNA) molecules delays human neonatal foreskin keratinocyte (HFKs) differentiation. Moreover, depletion of p300 increases the proliferative capacity of HFKs, extends the life span of cells and allows differentiated HFKs to re-enter the cell cycle. Studies indicate that depletion of p300 down-regulates the acetylation and expression of p53, and chromatin immunoprecipitation (ChIP) analysis shows that induction of p21 Waf1/CIP1 in early differentiation is a result of p300 dependent activation of p53 and that depletion of p21 Waf1/CIP1 results in the delay of differentiation and a phenotype similar to p300 depletion. Conclusions: p300 has a direct role in the control of cell growth and differentiation in primary epithelial cells, and p21 Waf1/CIP1 is an important mediator of these p300 functions

A Survey of non-white social service personnel in the State of Oregon

The National Association of Social Workers and the Council on Social Work Education are concerned with the eradication of racism within the social work profession and the nation at large. Graduate schools throughout the country are presently attempting to come to grips with this elusive and pervasive problem. The School of Social Work at Portland State University is among these schools. In early 1972, the Portland State University School of Social Work formalized and adopted a specific policy regarding recruitment, education, and issues concerning non-white students and communities. In doing so, this school became the first School of Social Work in the Northwest, perhaps in the nation, to have a specific, examinable policy covering its position of graduate education for non-whites. However, the genesis of this policy had extended back to 1971 when the need for a specific, consistent policy regarding non-whites and the School was being realized. It was during the subsequent task of developing this policy that the necessity for research in this area was keenly felt. The School of Social Work draws the majority of its students from the State of Oregon, specifically from the metropolitan area in and around Portland. The majority of its graduates choose to remain in Oregon to work. However, it was learned that little or no systematic information was available concerning the needs and programs of the practice community for non-white social service personnel. Since the School is committed both to education and to the service of the community, it became obvious that descriptive and concrete data were necessary. This research practicum is an attempt to examine this heretofore unexplored area in the State of Oregon