Cell response to RGD density in cross-linked artificial extracellular matrix protein films

This study examines the adhesion, spreading, and migration of human umbilical vein endothelial cells on cross-linked films of artificial extracellular matrix (aECM) proteins. The aECM proteins described here were designed for application in small-diameter grafts and are composed of elastin-like structural repeats and fibronectin cell-binding domains. aECM-RGD contains the RGD sequence derived from fibronectin; the negative control protein aECM-RDG contains a scrambled cell-binding domain. The covalent attachment of poly(ethylene glycol) (PEG) to aECM substrates reduced nonspecific cell adhesion to aECM-RDG-PEG but did not preclude sequence-specific adhesion of endothelial cells to aECM-RGD-PEG. Variation in ligand density was accomplished by the mixing of aECM-RGD-PEG and aECM-RDG-PEG prior to cross-linking. Increasing the density of RGD domains in cross-linked films resulted in more robust cell adhesion and spreading but did not affect cell migration speed. Control of cell-binding domain density in aECM proteins can thus be used to modulate cell adhesion and spreading and will serve as an important design tool as these materials are further developed for use in surgery, tissue engineering, and regenerative medicine

Preservice teachers’ creation of dynamic geometry sketches to understand trigonometric relationships

Dynamic geometry software can help teachers highlight mathematical relationships in ways not possible with static diagrams. However, these opportunities are mediated by teachers' abilities to construct sketches that focus users' attention on the desired variant or invariant relationships. This paper looks at two cohorts of preservice secondary mathematics teachers and their attempts to build dynamic geometry sketches that highlighted the trigonometric relationship between the angle and slope of a line on the coordinate plane. We identify common challenges in the construction of these sketches and present examples for readers to interact with that highlight these issues. Lastly, we discuss ways that mathematics teacher educators can help beginning teachers understand common pitfalls in the building of dynamic geometry sketches, which can cause sketches not to operate as intended

Young people’s civic attitudes and practices: England’s outcomes from the IEA International Civic and Citizenship Education Study (ICCS) - Research Report DFE-RR060

"ICCS is a large-scale study of pupil knowledge and understanding, dispositions and attitudes, which is administered across 38 countries worldwide. The results presented in this summary are based upon England’s national dataset, with reference to international- and European-level findings, and to findings from the IEA Civic Education Study (CIVED), which took place in 1999." - Background

Distributional composition using higher-order dependency vectors

This paper concerns how to apply compositional methods to vectors based on grammatical dependency relation vectors. We demonstrate the potential of a novel approach which uses higher-order grammatical dependency relations as features. We apply the approach to adjective-noun compounds with promising results in the prediction of the vectors for (held-out) observed phrases

Food-induced behavioral sensitization, its cross-sensitization to cocaine and morphine, pharmacological blockade, and effect on food intake

Repeated administration of abused drugs sensitizes their stimulant effects and results in a drug-paired environment eliciting conditioned activity. We tested whether food induces similar effects. Food-deprived male mice were given novel food during 30 min tests in a runway (FR group) that measured locomotor activity. Whereas the activity of this group increased with repeated testing, that of a group exposed to the runways but that received the food in the home cage (FH group), or of a group satiated by prefeeding before testing (SAT group), decreased. When exposed to the runways in the absence of food, the paired group was more active than the other groups (conditioned activity); no activity differences were seen in an alternative, non-food-paired, apparatus. Conditioned activity survived a 3-week period without runway exposure. Conditioned activity was selectively reduced by the opiate antagonist naltrexone (10-20 mg/kg) and by the noncompetitive AMPA receptor antagonist GYKI 52466 [1-(4-aminophenyl)-4-methyl-7,8-methylenedioxy-5H-2,3-benzodiazepine hydrochloride] (5-10 mg/kg). The D1 antagonist SCH23390 [R(+)-7-chloro-8-hydroxy-3-methyl-1-phenyl-2,3,4,5-tetrahydro-1H-3-benzazepine hydrochloride] (15-30 microg/kg) and D2 antagonist sulpiride (25-125 mg/kg) reduced activity nonspecifically. A single intraperitoneal dose of cocaine (10 mg/kg) or morphine (20 mg/kg) increased activity compared with saline, the stimulant effect being larger in the FR group, suggesting "cross-sensitization" to these drugs. However, pretreatment with GYKI 52466 or naltrexone at doses that suppressed conditioned activity in FR animals suppressed cross-sensitization to cocaine. When allowed ad libitum access to food in the runway, FR mice consumed more pellets in a time-limited test. Thus, many of the features of behavioral sensitization to drugs can be demonstrated using food reward and may contribute to excessive eating

Skew group algebras of piecewise hereditary algebras are piecewise hereditary

We show that the main results of Happel-Rickard-Schofield (1988) and Happel-Reiten-Smalo (1996) on piecewise hereditary algebras are coherent with the notion of group action on an algebra. Then, we take advantage of this compatibility and show that if G is a finite group acting on a piecewise hereditary algebra A over an algebraically closed field whose characteristic does not divide the order of G, then the resulting skew group algebra A[G] is also piecewise hereditary.Comment: 13 pages, typos corrected. To appear in J. Pure Appl. Algebr

The heat kernel on curvilinear polygonal domains in surfaces

We construct the heat kernel on curvilinear polygonal domains in arbitrary surfaces for Dirichlet, Neumann, and Robin boundary conditions as well as mixed problems, including those of Zaremba type. We compute the short time asymptotic expansion of the heat trace and apply this expansion to demonstrate a collection of results showing that corners are spectral invariants