Continuous Model for Homopolymers

We consider the model for the distribution of a long homopolymer in a potential field. The typical shape of the polymer depends on the temperature parameter. We show that at a critical value of the temperature the transition occurs from a globular to an extended phase. For various values of the temperature, including those at or near the critical value, we consider the limiting behavior of the polymer when its size tends to infinity

Embracing INTO: Library Plans and Campus Collaboration to Serve an Increased International Student Population

Universities are using private recruitment agencies to fast-track internationalization initiatives and realize tuition-based revenue increases. Colorado State University (CSU), with this dual aim of increasing the proportion of international students on campus and generating income via out-of-state tuition, signed a contract with INTO, a British organization that works to recruit international students to attend partner institutions from countries across five continents. International students, although not a homogenous population, as a whole do bring unique challenges. Our study examined how both campus and the library could prepare for the expected large influx of international students. Seeking to understand the INTO model and the effect it would have on campus, particularly in terms of resource planning, we conducted a series of interviews with INTO staff, librarians at other U.S. INTO institutions, and CSU faculty and staff who would interact most substantially with the INTO population. Various campus departments have made significant preparations to prepare for the growing INTO population, and we identified several steps that the CSU Libraries could take to better serve these students, including enhancing existing services and fostering new campus collaborations

Micro-political leadership strategies used by curriculum leaders in one Queensland school in implementing the national curriculum

Despite several countries having introduced a national curriculum, the literatureon how school leaders implement such curriculum is surprisingly scant. This article reportson one aspect of a larger study that investigated how members of a school curriculumleadership team implemented Australia’s first national curriculum. The aspect reported in thisarticle is concerned with leadership strategies used by these members in the implementationof this curriculum. The findings draw on semi-structured in-depth interviews of 29participants, comprising 17 members of this team and 11 teachers in the case school, and oneschool sector curriculum officer. Blase and Anderson’s (1995) micro-political leadershipmatrix was used to analyse the research findings, which shed light on the micro-politicalleadership practices regarding how school leaders implement large-scale mandatedcurriculum change. This analysis highlighted the need for those with curriculum leadership tounderstand micro-politics in leading such change.© 2018 Australian Council for Educational Leader

Species Trees from Highly Incongruent Gene Trees in Rice

Several methods have recently been developed to infer multilocus phylogenies by incorporating information from topological incongruence of the individual genes. In this study, we investigate 2 such methods, Bayesian concordance analysis and Bayesian estimation of species trees. Our test data are a collection of genes from cultivated rice (genus Oryza) and the most closely related wild species, generated using a high-throughput sequencing protocol and bioinformatics pipeline. Trees inferred from independent genes display levels of topological incongruence that far exceed that seen in previous data sets analyzed with these species tree methods. We identify differences in phylogenetic results between inference methods that incorporate gene tree incongruence. Finally, we discuss the challenges of scaling these analyses for data sets with thousands of gene trees and extensive levels of missing data

Up-regulation of delta-like 4 ligand in human tumor vasculature and the role of basal expression in endothelial cell function.

The Notch signaling pathway and the delta-like 4 ligand (DLL4) play key roles in embryonic vascular development. Many of the pathways involved in embryonic vascular development also play important roles in tumor angiogenesis. In this study, we assessed the expression of DLL4 in primary renal cancer and investigated the biological function of DLL4 in primary endothelial cells. Using real-time quantitative PCR and in situ hybridization, we showed that the expression of DLL4 was up-regulated within the vasculature of clear cell-renal cell carcinoma almost 9-fold more than normal kidney and was correlated with the expression of vascular endothelial growth factor (VEGF). The expression of DLL4 in endothelial cells was up-regulated by VEGF and basic fibroblast growth factor synergistically, and by hypoxia through hypoxia-inducible factor 1alpha. Down-regulation of DLL4 expression with RNA interference led to decreased expression of HEY1 and EphrinB2, and the inhibition of endothelial cell proliferation, migration, and network formation, all of which are important processes in tumor angiogenesis. The inhibition of proliferation occurred via the induction of cell cycle arrest in G0-G1 by increased expression of p21 and decreased phosphorylation of retinoblastoma. We conclude that an optimal window of the DLL4 expression is essential for tumor angiogenesis and that selective modulation of the DLL4 expression within human tumors may represent a potential novel antiangiogenic therapy

Human bladder cancer invasion model using rat bladder in vitro and its use to test mechanisms and therapeutic inhibitors of invasion

As well as being a passive support, the extracellular matrix also regulates key biological processes such as invasion, differentiation and angiogenesis. We have therefore developed an in vitro model of bladder cancer invasion using de-epithelialized rat bladder to allow for tumour cell–extracellular matrix interactions. Onto this we have seeded a panel of human bladder cancer cell lines (RT4, RT112, 253J and EJ28 (T24)) representing progression from well to poorly differentiated phenotypes and used as models of superficial to invasive bladder cancer. The better differentiated cell lines RT4 and RT112 reproducibly grew as stratified epithelium, whereas poorly differentiated EJ28 cells invaded across a broad front. Invasion was not simply related to proliferation rate, measured either as doubling time on plastic (non-invasive 253J and invasive EJ28 having the same doubling time) or by Ki-67 proliferation index within the model. We used the model to test the ability of 4 compounds that interfere with tumour cell–extracellular matrix interactions (suramin, N-acetylcysteine and the urokinase plasminogen activator pathway antagonists Å5 compound and monoclonal antibody Mab 3936) to inhibit invasion. At non-toxic concentrations, all significantly inhibited invasion (P< 0.05), although to varying degrees, suramin and Å5 almost completely and N-acetylcysteine the least. In conclusion, this model shows the urokinase system is important for bladder invasion and can be used to investigate other mechanisms of bladder cancer invasion and also for the testing of intravesical drugs. © 2001 Cancer Research Campaign http://www.bjcancer.co

Keystone coleopterans? Colonization by wood-feeding elmids of experimentally immersed woods in south-eastern Australia

Macroinvertebrates on immersed woods in streams in montane south-eastern Australia respond to differences in wood taxa, according to a 4-month colonization study of experimentally positioned sticks. Xylophagous elmids (Coleoptera : Elmidae) strongly preferred local native Eucalyptus over other types of wood including non-native softer timbers (Pinus and Alnus). Where gouging elmids were abundant (in native forest streams with native riparian vegetation), immersed Eucalyptus wood supported high abundances of other macroinvertebrates; in their absence (in open grassland streams), Eucalyptus supported few other macroinvertebrates. Macroinvertebrate-gouged channels were present disproportionately on Eucalyptus sticks relative to other wood species. It is proposed that xylophagous elmid beetles are the principal macroinvertebrate modifiers of wood in these south-eastern Australian streams, where their gouging of channels increases surface area, thereby facilitating colonization by other macroinvertebrates and wood-decaying microorganisms and fungi