359 research outputs found

    The existence of solutions for -Laplacian boundary value problems at resonance on the half-line

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    The concept of collective efficacy, defined as the combination of mutual trust and willingness to act for the common good, has received widespread attention in the field of criminology. Collective efficacy is linked to, among other outcomes, violent crime, disorder, and fear of crime. The concept has been applied to geographical units ranging from below one hundred up to several thousand residents on average. In this paper key informant- and focus group interview transcripts from four Swedish neighborhoods are examined to explore whether different sizes of geographical units of analysis are equally important for collective efficacy. The four studied neighborhoods are divided into micro-neighborhoods (N=12) and micro-places (N=59) for analysis. The results show that neighborhoods appear to be too large to capture the social mechanism of collective efficacy which rather takes place at smaller units of geography. The findings are compared to survey responses on collective efficacy (N=597) which yield an indication in the same direction through comparison of ICC-values and AIC model fit employing unconditional two-level models in HLM 6

    Iterative solution to singular nth-order nonlocal boundary value problems

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    By using the cone theory and the Banach contraction mapping principle, we study the existence and uniqueness of an iterative solution to the singular nth-order nonlocal boundary value problems

    Two Alleles of NF-κB in the Sea Anemone Nematostella vectensis Are Widely Dispersed in Nature and Encode Proteins with Distinct Activities

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    BACKGROUND. NF-κB is an evolutionarily conserved transcription factor that controls the expression of genes involved in many key organismal processes, including innate immunity, development, and stress responses. NF-κB proteins contain a highly conserved DNA-binding/dimerization domain called the Rel homology domain. METHODS/PRINCIPAL FINDINGS. We characterized two NF-κB alleles in the sea anemone Nematostella vectensis that differ at nineteen single-nucleotide polymorphisms (SNPs). Ten of these SNPs result in amino acid substitutions, including six within the Rel homology domain. Both alleles are found in natural populations of Nematostella. The relative abundance of the two NF-κB alleles differs between populations, and departures from Hardy-Weinberg equilibrium within populations indicate that the locus may be under selection. The proteins encoded by the two Nv-NF-κB alleles have different molecular properties, in part due to a Cys/Ser polymorphism at residue 67, which resides within the DNA recognition loop. In nearly all previously characterized NF-κB proteins, the analogous residue is fixed for Cys, and conversion of human RHD proteins from Cys to Ser at this site has been shown to increase DNA-binding ability and increase resistance to inhibition by thiol-reactive compounds. However, the naturally-occurring Nematostella variant with Cys at position 67 binds DNA with a higher affinity than the Ser variant. On the other hand, the Ser variant activates transcription in reporter gene assays more effectively, and it is more resistant to inhibition by a thiol-reactive compound. Reciprocal Cys<->Ser mutations at residue 67 of the native Nv-NF-κB proteins affect DNA binding as in human NF-κB proteins, e.g., a Cys->Ser mutation increases DNA binding of the native Cys variant. CONCLUSIONS/SIGNIFICANCE. These results are the first demonstration of a naturally occurring and functionally significant polymorphism in NF-κB in any species. The functional differences between these alleles and their uneven distribution in the wild suggest that different genotypes could be favored in different environments, perhaps environments that vary in their levels of peroxides or thiol-reactive compounds.National Institutes of Health (CA047763); National Science Foundation (FP-91656101-0); Environmental Protection Agency (F5E11155); Conservation International Marine Management Area Science Program; Boston University (SPRInG grant); Postdoctoral Scholar Program at the Woods Hole Oceanographic Institution; The Beacon Institute for Rivers and Estuaries; the J Seward Johnson Fund; Boston University (5 P42 ES07381

    Perturbed nonlocal fourth order equations of Kirchhoff type with Navier boundary conditions

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    Abstract We investigate the existence of multiple solutions for perturbed nonlocal fourth-order equations of Kirchhoff type under Navier boundary conditions. We give some new criteria for guaranteeing that the perturbed fourth-order equations of Kirchhoff type have at least three weak solutions by using a variational method and some critical point theorems due to Ricceri. We extend and improve some recent results. Finally, by presenting two examples, we ensure the applicability of our results
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