Optimal Resource Allocation in Random Networks with Transportation Bandwidths

We apply statistical physics to study the task of resource allocation in random sparse networks with limited bandwidths for the transportation of resources along the links. Useful algorithms are obtained from recursive relations. Bottlenecks emerge when the bandwidths are small, causing an increase in the fraction of idle links. For a given total bandwidth per node, the efficiency of allocation increases with the network connectivity. In the high connectivity limit, we find a phase transition at a critical bandwidth, above which clusters of balanced nodes appear, characterised by a profile of homogenized resource allocation similar to the Maxwell's construction.Comment: 28 pages, 11 figure

Experimental and computational studies of the copper borate complexes [(NHC)Cu(HBEt₃)] and [(NHC)Cu(HB(C₆F₅)₃)]

The synthesis of the Cu-borate complexes [(6Mes)Cu(HBR3)] featuring the unusual [HBEt3]−(5) and [HB(C6F5)3]−(6) ligands is described. Experimental and computational studies show both compounds feature a direct Cu–H interaction, but that while 5 is two-coordinate, 6 displays an additional, stabilizing Cu–Cipso(C6F5) interaction.</p

Beyond the Womb and the Tomb: Identity, (Dis)embodiment and the Life Course

Grounded in the authors’ theoretical and ethnographic work on pregnancy and social life after death, this article explores the ways in which the body is involved in processes of identification. With a focus on the embodied nature of social identity, the article nonetheless problematizes a model of the life course that begins at the moments of birth and ends at death. Instead, it offers a more extended temporal perspective and examines other ways in which identity may be claimed, for example, via material objects and practices which evoke the body as imagined or remembered. By documenting pre-birth and post-mortem identity-making of this kind, it demonstrates how the unborn and the dead may come into social existence. In addition, a cultural privileging of both the body and visuality is shown to shore up the capacity of material objects and practices to shape social identities in a highly selective fashion. The article therefore proposes that models of the life course need to accommodate the meanings of pre-birth and post-mortem materialities and so incorporate a conceptualization of social identity as contested, relational and inevitably incomplete

Men's passage to fatherhood: an analysis of the contemporary relevance of transition theory

This paper presents a theoretical analysis of men's experiences of pregnancy, birth and early fatherhood. It does so using a framework of ritual transition theory and argues that despite its earlier structural-functionalist roots, transition theory remains a valuable framework, illuminating contemporary transitions across the life course. The paper discusses the historical development of transition or ritual theory and, drawing upon data generated during longitudinal ethnographic interviews with men undergoing the transition to fatherhood, analyses its relevance in understanding contemporary experiences of fatherhood

Genomic characterization of a repetitive motif strongly associated with developmental genes in Drosophila

BACKGROUND: Non-coding DNA represents a high proportion of all metazoan genomes. Although an undetermined fraction of this DNA may be considered devoid of any function, it also contains important information residing in specific cis-regulatory sequences. RESULTS: We report a 27 bp motif that is overrepresented within the fly genome. This motif does not show any significant similarity with transposon sequences and is strongly associated with genes involved in development and/or signal transduction. The 27 bp motif is preferentially located within introns, and has a tendency to be present in multiple copies around genes. Furthermore, it is often found embedded in known non-coding regulatory regions. The regulatory network defined by this motif is partially shared in D. pseudoobscura. CONCLUSION: We have identified a 27 bp cis-regulatory sequence widely distributed within the Drosophila genome in association with developmental genes. This motif may be very useful towards the annotation of functional regulatory regions within the Drosophila genome and the construction of regulatory networks of Drosophila development

The role of genomic location and flanking 3'UTR in the generation of functional levels of variant surface glycoprotein in Trypanosoma brucei

Trypanosoma brucei faces relentless immune attack in the mammalian bloodstream, where it is protected by an essential coat of Variant Surface Glycoprotein (VSG) comprising ∼10% total protein. The active VSG gene is in a Pol I-transcribed telomeric expression site (ES). We investigated factors mediating these extremely high levels of VSG expression by inserting ectopic VSG117 into VSG221 expressing T. brucei. Mutational analysis of the ectopic VSG 3′UTR demonstrated the essentiality of a conserved 16-mer for mRNA stability. Expressing ectopic VSG117 from different genomic locations showed that functional VSG levels could be produced from a gene 60 kb upstream of its normal telomeric location. High, but very heterogeneous levels of VSG117 were obtained from the Pol I-transcribed rDNA. Blocking VSG synthesis normally triggers a precise precytokinesis cell-cycle checkpoint. VSG117 expression from the rDNA was not adequate for functional complementation, and the stalled cells arrested prior to cytokinesis. However, VSG levels were not consistently low enough to trigger a characteristic ‘VSG synthesis block’ cell-cycle checkpoint, as some cells reinitiated S phase. This demonstrates the essentiality of a Pol I-transcribed ES, as well as conserved VSG 3′UTR 16-mer sequences for the generation of functional levels of VSG expression in bloodstream form T. brucei

A Catalog of Neutral and Deleterious Polymorphism in Yeast

The abundance and identity of functional variation segregating in natural populations is paramount to dissecting the molecular basis of quantitative traits as well as human genetic diseases. Genome sequencing of multiple organisms of the same species provides an efficient means of cataloging rearrangements, insertion, or deletion polymorphisms (InDels) and single-nucleotide polymorphisms (SNPs). While inbreeding depression and heterosis imply that a substantial amount of polymorphism is deleterious, distinguishing deleterious from neutral polymorphism remains a significant challenge. To identify deleterious and neutral DNA sequence variation within Saccharomyces cerevisiae, we sequenced the genome of a vineyard and oak tree strain and compared them to a reference genome. Among these three strains, 6% of the genome is variable, mostly attributable to variation in genome content that results from large InDels. Out of the 88,000 polymorphisms identified, 93% are SNPs and a small but significant fraction can be attributed to recent interspecific introgression and ectopic gene conversion. In comparison to the reference genome, there is substantial evidence for functional variation in gene content and structure that results from large InDels, frame-shifts, and polymorphic start and stop codons. Comparison of polymorphism to divergence reveals scant evidence for positive selection but an abundance of evidence for deleterious SNPs. We estimate that 12% of coding and 7% of noncoding SNPs are deleterious. Based on divergence among 11 yeast species, we identified 1,666 nonsynonymous SNPs that disrupt conserved amino acids and 1,863 noncoding SNPs that disrupt conserved noncoding motifs. The deleterious coding SNPs include those known to affect quantitative traits, and a subset of the deleterious noncoding SNPs occurs in the promoters of genes that show allele-specific expression, implying that some cis-regulatory SNPs are deleterious. Our results show that the genome sequences of both closely and distantly related species provide a means of identifying deleterious polymorphisms that disrupt functionally conserved coding and noncoding sequences

Correlations between Functional Balance and Postural Sway in a Geriatric Population: A Pilot Study

1Jordan, R., 1Hertz, J., 1Kieffer, H.S., 2Sollenberger, B. 1Messiah College, Grantham, PA and 2CPRS Physical Therapy, Elizabethtown, PA. Purpose: The purpose of this study was to compare various clinical measures of balance and postural sway in the elderly population. Methods: Thirteen independently living subjects (4 males and 9 females, age =83.5±10.66 and 81.3±7.68 years, respectively) participated in a quasi-experimental, comparative study. The subjects completed a series of functional balance protocols and questionnaires that included the Falls Efficacy Scale (FES), Stride Length (SL) and Dynamic Gait Index (DGI). In addition, a static standing eyes-open protocol was completed using an AMTI Forceplate and ACCUSWAY balance software to measure center of pressure (COP) deviations of each subject during a standard two-foot open stance. The variables of COP deviancy included total path length and maximum velocity in anterior-posterior (Vymax) and medial-lateral (Vxmax) planes. Multiple Pearson’s Product Correlation Coefficients were run to assess the relationship between functional measures. In addition, correlations were also run between the functional and static measures of balance. Results: High positive correlations were found among functional balance measures, ranging from 0.72 to 0.838. However, low correlations ranging from 0.35 to 0.47 were found between the functional and static measures. Conclusion: The high correlations between functional measures indicate that the FES, SL and DGI have similar predictive abilities for assessing dynamic balance. In contrast, the low correlations between the functional and static tests suggest that different aspects of balance are measured. The low predictability found between functional balance and static measures indicates that future research should investigate the utility of conducting static tests that minimize the base of support and challenge the control of COP