Experimental investigation of an axisymmetric free jet with an initially uniform velocity profile

An experimental investigation was conducted to determine the flow characteristics of a circular free helium jet having an initially uniform velocity profile. Complete velocity profiles are presented at Reynolds numbers of 1027 and 4571 at 0, 3, 6, 10, 15, and 20 nozzle diameters (where possible) from the nozzle exit. Centerline velocity decay and potential core length were obtained over a range of Reynolds numbers from 155 to 5349 at distances up to and including 25 nozzle diameters from the nozzle exit. The angles of spread associated with the diffusion of the jet downstream of the nozzle are also given. Axial jet momentum flux and entrained mass flux, at various distances downstream of the nozzle, are presented as a function of the jet Reynolds number

Implications of new measurements of O-16 + p + C-12,13, N-14,15 for the abundances of C, N isotopes at the cosmic ray source

The fragmentation of a 225 MeV/n O-16 beam was investigated at the Bevalac. Preliminary cross sections for mass = 13, 14, 15 fragments are used to constrain the nuclear excitation functions employed in galactic propagation calculations. Comparison to cosmic ray isotonic data at low energies shows that in the cosmic ray source C-13/C approximately 2% and N-14/0=3-6%. No source abundance of N-15 is required with the current experimental results

Explaining science: integrating science literacy into a research-based undergraduate program

Science literacy, which we define as the writing, reading and information research skills required to practice science, is a central component of the Integrated Science Program (iSci) at McMaster University. Concepts developed in the interactive, collaboratively-taught science literacy classes support the research projects that form the basis of learning in iSci. The aim of the science literacy component is to prepare the next generation of professional scientists to communicate not only within academia, but also to the wider community. In this presentation, we will describe the format of iSci and the role of science literacy within it. We shall then discuss the various activities and techniques used to introduce professional skills throughout the four-year program. iSci students gain experience in writing for audiences through two main conduits. One is a science blog: an on-going, individual, low-stakes writing practice activity. The other is a series of research project assessed deliverables: high-stakes, collaborative writing tasks. These take the form of oral presentations, posters, debates, abstracts, lab reports, and papers. Students are supported in developing writing skills (from research notes, through drafting, review, and editing) by feedback from instructors, dedicated TAs, and their peers. Information literacy skills, including source evaluation and information retrieval, are developed from the start of the Program. iSci has strong links to the University Library and students are introduced to primary literature early in the course. We report on results from the first two years of the science literacy initiative, and outline plans for further developments and evaluations

Note and Comment

Effect of Taking Possession of Mortgaged Property Under a Chattel Mortgage as Against a Junior Mortgagee; The Effect of the Reunion of the Cumberland Presbyterian Church With the Presbyterian Church in the United States of America Upon the Property of the Former; The Exclusive Use of Part of Railroad Station Grounds by Hackmen; Conflict of Jurisdiction in Bankruptcy Cases Between Federal and State Courts; Right of the Legislature to Amend Corporate Charters Under the Reserved Power; Can A Purchaser From a Tenant Acquire Title by Adverse Possession?; Can a Mortgagor After the Execution of the Mortgage Create an Easement in the Mortgage Security?; The Ohio Bulk Sales Law

Family support and ease of access link socio-economic status and sports club membership in adolescent girls : a mediation study

Background Much research has been conducted into the determinants of physical activity (PA) participation among adolescent girls. However, the more specific question of what are the determinants of particular forms of PA participation, such as the link between participation through a sports club, has not been investigated. Accordingly, the aim of this study was to investigate the relationships between participation in a sports club and socio-economic status (SES), access to facilities, and family and peer support, for female adolescents.Methods A survey of 732 female adolescent school students (521 metropolitan, 211 non-metropolitan; 489 Year 7, 243 Year 11) was conducted. The survey included demographic information (living arrangements, ethnicity indicators, and indicators of SES such as parental education and employment status and locality); access to facilities; and family and peer support (travel, encouragement, watching, praise, joint participation). For each characteristic, sports club participants and non-participants were compared using chi-square tests. Multiple mediation analyses were used to investigate the role of access, family and peer support in the link between SES and sport participation.Results There were significant associations (p&lt;0.05) between sports club participation and: all demographic characteristics; all measures of family and peer support; and access to sport-related facilities. Highest levels of participation were associated with monolingual Australian-born families, with two parents, at least one of whom was well-educated, with both parents employed, and high levels of parental assistance, engagement and support. Participation in club sport among both younger and older adolescent girls was significantly positively associated with the SES of both their neighbourhoods and their households, particularly in metropolitan areas. These associations were most strongly mediated by family support and by access to facilities.Conclusions To facilitate and promote greater participation in club sport among adolescent girls from low SES neighbourhoods and households, strategies should target modifiable determinants such as facility access and parental support. This will involve improving access to sports facilities and promoting, encouraging and assisting parents to provide support for their daughters&rsquo; participation in sport clubs.<br /

Improved single-chain transactivators of the Tet-On gene expression system

BACKGROUND: The Tet-Off (tTA) and Tet-On (rtTA) regulatory systems are widely applied to control gene expression in eukaryotes. Both systems are based on the Tet repressor (TetR) from transposon Tn10, a dimeric DNA-binding protein that binds to specific operator sequences (tetO). To allow the independent regulation of multiple genes, novel Tet systems are being developed that respond to different effectors and bind to different tetO sites. To prevent heterodimerization when multiple Tet systems are expressed in the same cell, single-chain variants of the transactivators have been constructed. Unfortunately, the activity of the single-chain rtTA (sc-rtTA) is reduced when compared with the regular rtTA, which might limit its application. RESULTS: We recently identified amino acid substitutions in rtTA that greatly improved the transcriptional activity and doxycycline-sensitivity of the protein. To test whether we can similarly improve other TetR-based gene regulation systems, we introduced these mutations into tTA and sc-rtTA. Whereas none of the tested mutations improved tTA activity, they did significantly enhance sc-rtTA activity. We thus generated a novel sc-rtTA variant that is almost as active and dox-sensitive as the regular dimeric rtTA. This variant was also less sensitive to interference by co-expressed TetR-based tTS repressor protein and may therefore be more suitable for applications where multiple TetR-based regulatory systems are used. CONCLUSION: We developed an improved sc-rtTA variant that may replace regular rtTA in applications where multiple TetR-based regulatory systems are used