Recommended safety guides for industrial laboratories and shops

Booklet provides references to 29 publications providing information on hazard control and approved safety practices. Areas include pressurized gas and vacuum systems. Guidelines are presented for safeguarding facilities where machinery, equipment, electrical devices, or hazardous chemicals are used

Changes in Aphid Host Plant Diet Influence the Small-RNA Expression Profiles of Its Obligate Nutritional Symbiont, Buchnera.

Plants are a difficult food resource to use, and herbivorous insects have evolved a variety of mechanisms that allow them to fully exploit this poor nutritional resource. One such mechanism is the maintenance of bacterial symbionts that aid in host plant feeding and development. The majority of these intracellular symbionts have highly eroded genomes that lack many key regulatory genes; consequently, it is unclear if these symbionts can respond to changes in the insect's diet to facilitate host plant use. There is emerging evidence that symbionts with highly eroded genomes express small RNAs (sRNAs), some of which potentially regulate gene expression. In this study, we sought to determine if the reduced genome of the nutritional symbiont (Buchnera) in the pea aphid responds to changes in the aphid's host plant diet. Using transcriptome sequencing (RNA-seq), Buchnera sRNA expression profiles were characterized within two Buchnera life stages when pea aphids fed on either alfalfa or fava bean. Overall, this study demonstrates that Buchnera sRNA expression changes not only with life stage but also with changes in aphid host plant diet. Of the 321 sRNAs characterized in this study, 47% were previously identified and 22% showed evidence of conservation in two or more Buchnera taxa. Functionally, 13 differentially expressed sRNAs were predicted to target genes related to pathways involved in essential amino acid biosynthesis. Overall, results from this study reveal that host plant diet influences the expression of conserved and lineage-specific sRNAs in Buchnera and that these sRNAs display distinct host plant-specific expression profiles among biological replicates.IMPORTANCE In general, the genomes of intracellular bacterial symbionts are reduced compared to those of free-living relatives and lack many key regulatory genes. Many of these reduced genomes belong to obligate mutualists of insects that feed on a diet that is deficient in essential nutrients, such as essential amino acids. It is unclear if these symbionts respond with their host to changes in insect diet, because of their reduced regulatory capacity. Emerging evidence suggests that these symbionts express small RNAs (sRNAs) that regulate gene expression at the posttranscriptional level. Therefore, in this study, we sought to determine if the reduced genome of the nutritional symbiont Buchnera in the pea aphid responds to changes in the aphid's host plant diet. This study demonstrates for the first time that Buchnera sRNAs, some conserved in two or more Buchnera lineages, are differentially expressed when aphids feed on different plant species and potentially target genes within essential amino acid biosynthesis pathways

Parrondo's games with chaotic switching

This paper investigates the different effects of chaotic switching on Parrondo's games, as compared to random and periodic switching. The rate of winning of Parrondo's games with chaotic switching depends on coefficient(s) defining the chaotic generator, initial conditions of the chaotic sequence and the proportion of Game A played. Maximum rate of winning can be obtained with all the above mentioned factors properly set, and this occurs when chaotic switching approaches periodic behavior.Comment: 11 pages, 9 figure

The effect of tetrathionate on the stability and immunological properties of muscle triosephosphate dehydrogenases

Tetrathionate effect on stability and immunological properties of muscle triosephosphate dehydrogenase

Galaxy pairs as a probe for mergers at z ~ 2

In this work I investigate the redshift evolution of pair fraction of a sample of 196 massive galaxies from z = 0 to 3, selected from the COSMOS field. We find that on average a massive galaxy undergoes ~ 1.1 \pm 0.5 major merger since z = 3. I will review the current limitations of using the pair fraction as a probe for quantifying the impact of mergers on galaxy evolution. This work is based on the paper Man et al. (2011).Comment: 4 pages; to appear on the Conference Proceedings for "Galaxy Mergers in an Evolving Universe", held in Hualien, Taiwan (October 2011

How Much Can High-Quality Universal Pre-K Reduce Achievement Gaps?

Many children of color and children from low-income families enter kindergarten without the academic skills they need to succeed. Compared to their white peers, African American and Hispanic children are anywhere from 9 to 10 months behind in math and 7 to 12 months behind in reading when they enter kindergarten. These achievement gaps are concerning: Math and reading abilities at kindergarten entry are powerful predictors of later school success, and children who enter kindergarten already behind are unlikely to catch up. Moreover, in the past 50 years, minimal progress has been made toward reducing these achievement gaps. Ensuring that all children are entering kindergarten with the foundational academic skills they need to succeed is a major priority for researchers, policymakers, and practitioners alike. Early childhood education programs show promise toward this goal. Research suggests that participation in a high-quality early childhood education program can enhance children's development, reduce achievement gaps at kindergarten entry, and even have long-term benefits for children's school trajectories. However, access to high-quality pre-K in the United States remains quite low and highly unequal due to two problems. First, although pre-K attendance has increased in the past two decades, rates of access to early education vary widely as a function of children's socioeconomic backgrounds: African American, Hispanic, and low-income children are less likely to access center-based early childhood education than their white and more affluent peers. Second, the quality of most early education programs -- particularly those attended by low-income children of color -- is not high enough to substantially improve academic readiness. Recognizing the tremendous potential for high-quality preschool to improve children's outcomes, this report considers how a universal publicly funded prekindergarten program in the United States could decrease both disparities in access to early learning and achievement gaps at kindergarten entry. Data from two nationally representative datasets and prior results from evaluations of high-quality universal pre-kindergarten were analyzed to estimate the extent to which a national high-quality universal pre-K, or UPK, program would reduce achievement gaps at kindergarten entry based on children's race/ethnicity and income

A TECHNIQUE TO ESTIMATE INPUT PRODUCTIVITY FROM FARM DATA

Productivity Analysis,

A comparative study of the evolution of enzymes and nucleic acids Semiannual progress report, 1 May - 30 Nov. 1967

Immunological and enzymological approaches to evolution of enzymes and nucleic acid

Stress and large-scale spatial structures in dense, driven granular flows

We study the appearance of large-scale dynamical heterogeneities in a simplified model of a driven, dissipative granular system. Simulations of steady-state gravity-driven flows of inelastically colliding hard disks show the formation of large-scale linear structures of particles with a high collision frequency. These chains can be shown to carry much of the collisional stress in the system due to a dynamical correlation that develops between the momentum transfer and time between collisions in these "frequently-colliding" particles. The lifetime of these dynamical stress heterogeneities is seen to grow as the flow velocity decreases towards jamming, leading to slowly decaying stress correlations reminiscent of the slow dynamics observed in supercooled liquids.Comment: 8 pages, 6 figure