The hub number of a graph

A hub set in a graph G is a set U⊆V(G) such that any two vertices outside U are connected by a path whose internal vertices lie in U. We prove that h(G)?hc(G)?γc(G)?h(G)+1, where h(G), hc(G), and γc(G), respectively, are the minimum sizes of a hub set in G, a hub set inducing a connected subgraph, and a connected dominating set. Furthermore, all graphs with γc(G)>hc(G)?4 are obtained by substituting graphs into three consecutive vertices of a cycle; this yields a polynomial-time algorithm to check whether hc(G)=γc(G).     

Regulation of polyunsaturated fatty acid metabolism in tissue phospholipids of obese (fa/fa) and lean (fa/−) Zucker rats. 1. Effect of dietary lipids on cardiac tissue

The present investigation addressed three questions: (i) Does the obese syndrome alter the fatty acid composition of cardiac tissue and membrane phospholipids in obese (fa/fa) rats? (ii) Are changes, if they occur, similar to those reported for tissues of the genetically obese (ob/ob) mouse? (iii) Can cardiac tissue phospholipids and their component fatty acids be modified by dietary lipids and if so does this occur to the same extent in both fa/fa and lean (Fa/?) rats? Proportions of polyunsaturated fatty acids (PUFA) in cardiac total phospholipids of fa/fa rats differed significantly from those of Fa/? rats and from those reported for ob/ob mice. Increased 18∶2n?6 and decreased 20∶4n?6 and 22∶6n?3 in fa/fa rats indicated impaired PUFA metabolism, possibly reduced Δ6 and/or Δ5 desaturase activity, compared with Fa/? rats. No differences in hepatic Δ6 and Δ5 desaturase activity between fa/fa and Fa/? were found but enhanced activity of Δ9 desaturase activity in fa/fa as compared to Fa/? was evident. Inclusion of sunflower oil (SO) or triolein (TO) at 5% and 20% by weight in the diet elicited marked changes in the fatty acyl composition of cardiac phospholipids in both fa/fa and Fa/? rats when compared with animals fed the control Oxoid diet alone. Supplementation with triolein was most effective, reducing 18∶2n?6 and increasing 20∶4n?6 proportions in fa/fa rats so that they resembled those in Fa/? rats fed the control Oxoid diet. The type of fat rather than the amount of its dietary intake appears to be the main determinant of the observed changes in phospholipid composition. Pair feeding hyperphagic fa/fa rats to the lower intakes of Fa/? rats did not abolish the characteristic differences in the proportions of PUFA in cardiac phospholipids between the two phenotypes. The effect of triolein on cardiac phospholipid fatty acid composition in the present studies is intriguing and may be relevant in understanding the beneficial role of dietary olive oil in ameliorating cardiovascular disease in man.     

Reimagining writing program web sites as pedagogical tools

I argue that conversations about the pedagogical applications of web sites and HTML should be extended to include applications of these technologies on the programmatic level. I specifically examine the experience of the Rutgers writing program and the reconception of the writing program web site through a student-centered, content-driven, collaboratively constructed model in terms of Cynthia Selfe’s (1999) notion of critical technological literacy.     

Of flags: Online queer identities, writing classrooms, and action horizons

In this article I argue that lesbian, gay, bisexual, transgender (LGBT) and queer pedagogies have been too exclusively focused on identity. The problem with these identity-based pedagogies is that they cannot fully account for actual LGBT identities, due in part to a continued multiplication of these identities online. I use LGBT pride flags to illustrate the ways in which these identities have proliferated, presenting a theoretical limit for current understandings of queer and LGBT pedagogy. As an alternative, I introduce the notion of the action horizon, which forms a pedagogy that encourages students to imagine themselves as actors in the public sphere, shaping policies and confronting complex real-world problems. The various LGBT pride flags then serve as material in three examples—an online asynchronous discussion, writing in a computer classroom, and paper assignments—all of which prompt students to enact the action horizon. Despite the possibilities for real-world engagement offered by the action horizon, success with this pedagogy can be limited in terms of LGBT issues, and so I end with some consideration of the implications and limitations of this kind of teaching.     

Prevalence and Concentration of Arcobacter spp. on Australian Beef Carcasses

The International Commission on Microbiological Specifications for Foods (ICMSF) classified Arcobacter spp. as emerging pathogens in 2002. Arcobacter spp. have been isolated from numerous food products at retail and from animal carcasses and feces at slaughter. A survey was conducted to determine both the prevalence and concentration of Arcobacter spp. on prechill beef carcasses. Surface swab samples were collected from 130 beef carcasses at the end of processing, prior to chilling. The concentration of Arcobacter spp. was determined by a most-probable-number per square centimeter (3 by 3) method with a limit of detection of 0.12 CFU/cm(2). Of the 100 carcasses examined from export abattoirs, 20 (20.0%) were contaminated with Arcobacter spp., and 5 of these had quantifiable levels of contamination ranging from 0.12 to 0.31 CFU/cm(2). Of the 30 carcasses examined at a pet food abattoir, 25 (83.3%) were contaminated with Arcobacter spp., and 10 of these had quantifiable levels of contamination ranging from 0.12 to 0.95 CFU/cm(2). Three species of Arcobacter, A. butzleri, A. cryaerophilus, and A. skirowii, were identified by PCR. Each of the species was present in an approximately equal ratio from export abattoirs. This study demonstrates that slaughter practices at export abattoirs are sufficient to maintain both low prevalence and low levels of contamination of beef carcasses with Arcobacter spp.     

Pharmacokinetic evaluation of a 1,3-dicyclohexylurea nanosuspension formulation to support early efficacy assessment

Time and resource constraints necessitate increasingly early decisions to advance or halt pre-clinical drug discovery programs. Early discovery or “tool” compounds may be potent inhibitors of new targets, but all too often they exhibit poor pharmaceutical and pharmacokinetic properties that make early assessment of in vivo efficacy difficult. 1,3-Dicyclohexylurea, a potent and selective inhibitor of soluble epoxide hydrolase (sEH), reduces blood pressure in hypertensive preclinical animal models when administered intraperitoneally using DMSO/corn oil as a delivery vehicle. However, the poor aqueous solubility of DCU poses a challenge for in vivo dosing in a multiple dose situation. Therefore, we developed a nanosuspension formulation of DCU to support oral, intravenous bolus and intravenous infusion dosing. Use of the nanosuspension formulation maintained DCU free plasma levels above the sEH IC50 and demonstrated that the application of formulation technology can accelerate in vivo evaluation of new targets by enabling pharmacodynamic studies of poorly soluble compounds. This study was supported by Pharmacokinetics, Dynamics and Metabolism at Pfizer.     

Measuring the discrepancy between current and ideal spiritual and religious functioning in problem drinkers.

The idea that spiritual and religious functioning (SRF) is associated with alcohol misuse is generally supported, but problems with typical research methods limit the utility of findings. Problems in SRF were conceptualized as discrepancies between current and ideal SRF. Two separate studies were conducted to develop and evaluate a scale to measure the subjective importance and adequacy of aspects of SRF that seem to be associated with alcohol problems. The 1st study suggested that a questionnaire developed to evaluate self-reported ratings of current and ideal SRF is both internally consistent and temporally stable. In the 2nd study, the questionnaire was administered to persons seeking treatment for alcohol problems and persons who indicated that they had never sought treatment for an alcohol problem. Results indicate that those with a drinking problem were more likely to report substantial discrepancies between current and ideal SRF, supporting the validity of the measure as an indicator of problems in SRF. The usefulness of this method for treatment and research is discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Affinity and kinetic analysis of L-selectin (CD62L) binding to glycosylation-dependent cell-adhesion molecule-1

The selectin family of cell adhesion molecules mediates the tethering and rolling of leukocytes on blood vessel endothelium. It has been postulated that the molecular basis of this highly dynamic adhesion is the low affinity and rapid kinetics of selectin interactions. However, affinity and kinetic analyses of monomeric selectins binding their natural ligands have not previously been reported. Leukocyte selectin (L-selectin, CD62L) binds preferentially to O-linked carbohydrates present on a small number of mucin-like glycoproteins, such as glycosylation-dependent cell adhesion molecule-1 (GlyCAM-1), expressed in high endothelial venules. GlyCAM-1 is a soluble secreted protein which, following binding to CD62L, stimulates beta2-integrin-mediated adhesion of lymphocytes. Using surface plasmon resonance, we show that a soluble monomeric form of CD62L binds to purified immobilized GlyCAM-1 with a dissociation constant (Kd) of 108 microM. CD62L dissociates from GlyCAM-1 with a very fast dissociation rate constant (>/=10 s-1) which agrees well with the reported dissociation rate constant of CD62L-mediated leukocyte tethers. The calculated association rate constant is >/=10(5) M-1 s-1. At concentrations just above its mean serum level (approximately 1.5 microg/ml or approximately 30 nM), GlyCAM-1 binds multivalently to immobilized CD62L. It follows that soluble GlyCAM-1 may cross-link CD62L when it binds to cells, suggesting a mechanism for signal transduction.     

Trading reliability targets within a supply chain using Shapley's value

The development of complex systems involves a multi-tier supply chain, with each organisation allocated a reliability target for their sub-system or component part apportioned from system requirements. Agreements about targets are made early in the system lifecycle when considerable uncertainty exists about the design detail and potential failure modes. Hence resources required to achieve reliability are unpredictable. Some types of contracts provide incentives for organisations to negotiate targets so that system reliability requirements are met, but at minimum cost to the supply chain. This paper proposes a mechanism for deriving a fair price for trading reliability targets between suppliers using information gained about potential failure modes through development and the costs of activities required to generate such information. The approach is based upon Shapley's value and is illustrated through examples for a particular reliability growth model, and associated empirical cost model, developed for problems motivated by the aerospace industry. The paper aims to demonstrate the feasibility of the method and discuss how it could be extended to other reliability allocation models.     

Estimating rate of occurrence of rare events with empirical bayes: A railway application

Classical approaches to estimating the rate of occurrence of events perform poorly when data are few. Maximum likelihood estimators result in overly optimistic point estimates of zero for situations where there have been no events. Alternative empirical-based approaches have been proposed based on median estimators or non-informative prior distributions. While these alternatives offer an improvement over point estimates of zero, they can be overly conservative. Empirical Bayes procedures offer an unbiased approach through pooling data across different hazards to support stronger statistical inference.This paper considers the application of Empirical Bayes to high consequence low-frequency events, where estimates are required for risk mitigation decision support such as as low as reasonably possible. A summary of empirical Bayes methods is given and the choices of estimation procedures to obtain interval estimates are discussed. The approaches illustrated within the case study are based on the estimation of the rate of occurrence of train derailments within the UK. The usefulness of empirical Bayes within this context is discussed.