Reverse Chv\'atal-Gomory rank

We introduce the reverse Chv\'atal-Gomory rank r*(P) of an integral polyhedron P, defined as the supremum of the Chv\'atal-Gomory ranks of all rational polyhedra whose integer hull is P. A well-known example in dimension two shows that there exist integral polytopes P with r*(P) equal to infinity. We provide a geometric characterization of polyhedra with this property in general dimension, and investigate upper bounds on r*(P) when this value is finite.Comment: 21 pages, 4 figure

Psychological functioning in couples undergoing in vitro fertilisation (IVF) or donor insemination (DI) treatment for infertility

This study was designed to investigate the emotional, marital and sexual functioning of female infertility patients and their male partners, to examine factors influencing psychological functioning, and to assess ways that patients cope with their infertility. Patients attending one of two London clinics for in vitro fertilisation (IVF) or donor insemination (DI) treatment were assessed prior to treatment and approximately 9 months later. At initial assessment, fifty-nine women were interviewed and completed self-report questionnaires assessing state and trait anxiety, depression, sex role, marital and sexual functioning and strategies used to cope with infertility. Thirty-four of their partners also completed questionnaires. Prior to treatment, participants experienced high levels of anxiety, but not depression. They did not have significant levels of marital or sexual problems. High levels of avoidance coping were associated with higher levels of anxiety and depression, but coping strategies were not related to marital or sexual functioning. More female participants were classified as having feminine sex roles in comparison with the general population. High levels of masculinity were associated with lower anxiety but not depression for both men and women. Female IVF patients had higher trait anxiety than female DI patients, but there were no other differences in psychological functioning between the treatment groups. In terms of factors influencing emotional functioning, avoidance coping was a consistent predictor of anxiety and depression in both women and men. The response to follow up was poor: only 46% of female participants completed assessments. For most participants, treatment was unsuccessful. There was a strong relationship between functioning at initial and follow up assessment for these patients. Couples who undergo IVF and DI are a select group of patients: although anxious prior to treatment their emotional functioning is generally good. Reasons for these findings are discussed and proposals for interventions to reduce anxiety and enable appropriate coping strategies are made

Microstructure Diffusion Models with Secondary Flux

AbstractTotally fissured media in which the cells are isolated by the fissure system are effectively described by double porosity models with microstructure. These models contain the geometry of the individual cells or pores in the medium and the flux across their interface with the fissures which surrounds them. We extend these models to include the case of partially fissured media in which a secondary flux effect arises from cell-to-cell diffusion paths. These quasilinear problems are formulated in appropriate spaces for which the cells respond to the local linearization of the fissure pressure. It is shown that they are well-posed and that the solutions depend continuously on parameters that determine the models

Process specifications and standards for the 1970 thorium campaign in the Purex Plant

The process specifications and standards for thorium processing operations in the Purex Plant are presented. These specifications represent currently known limits within which plant processing conditions must be maintained to meet defined product requirements safely and with minimum effect on equipment service life. These specifications cover the general areas of feed, essential materials, and chemical hazards. (LK

Trying to end the war on the world: the campaign to proscribe military ecocide

Military ecocide, the destruction of the natural environment in the course of fighting or preparing for war, has a long history and remains a regular feature of contemporary conflicts. Efforts to prohibit this in international law were initiated after the US’ notorious defoliation campaign in the Vietnam War in the 1960s and have advanced since then. Legal ambiguities and the defence of military necessity have limited the application of this body of law but the proscription of ecocide has, nonetheless, progressed and looks set to develop further. Normative change driven by scientists, environmentalists and legal experts has raised awareness of and stigmatised such practises to the extent that recourse to the worst excesses of ecocide now appears to have lessened and some recompense for past crimes has been made. Military activities, though, still inflict a heavy cost on the environment

The complications of ‘hiring a hubby’: gender relations and the commoditisation of home maintenance in New Zealand

This paper examines the commoditization of traditionally male domestic tasks through interviews with handymen who own franchises in the company ‘Hire a Hubby’ in New Zealand and homeowners who have paid for home repair tasks to be done. Discussions of the commoditization of traditionally female tasks in the home have revealed the emotional conflicts of paying others to care as well as the exploitative and degrading conditions that often arise when work takes place behind closed doors. By examining the working conditions and relationships involved when traditionally male tasks are paid for, this paper raises important questions about the valuing of reproductive labour and the production of gendered identities. The paper argues that while working conditions and rates of pay for ‘hubbies’ are better than those for people undertaking commoditized forms of traditionally female domestic labour, the negotiation of this work is still complex and implicated in gendered relations and identities. Working on the home was described by interviewees as an expression of care for family and a performance of the ‘right’ way to be a ‘Kiwi bloke’ and a father. Paying others to do this labour can imply a failure in a duty of care and in the performance of masculinity

Hydrellia lagarosiphon Deeming (Diptera: Ephydridae), a potential biological control agent for the submerged aquatic weed, Lagarosiphon major (Ridl.) Moss ex Wager (Hydrocharitaceae)

The leaf-mining fly, Hydrellia lagarosiphon Deeming (Diptera: Ephydridae), was investigated in its native range in South Africa, to determine its potential as a biological control agent for Lagarosiphon major (Ridl.) Moss ex Wager (Hydrocharitaceae), an invasive submerged macrophyte that is weedy in many parts of the world. The fly was found throughout the indigenous range of the plant in South Africa. High larval abundance was recorded at field sites with nearly all L. major shoots sampled ontaining larvae, with densities of up to 10 larvae per shoot. Adults laid batches of up to 15 eggs, usually on the abaxial sides of L. major leaves. The larvae mined internally, leaving the epidermal tissues of the upper and lower leaves intact. The larvae underwent three instars which took an average of 24 days and pupated within the leaf tissue, from which the adults emerged. Impact studies in the laboratory showed that H. lagarosiphon larval feeding significantly restricted the formation of L. major side branches. Based on its biology and damage caused to the plant, Hydrellia lagarosiphon could be considered as a useful biological control candidate for L. major in countries where the plant is invasive

Neutron star properties in the quark-meson coupling model

The effects of internal quark structure of baryons on the composition and structure of neutron star matter with hyperons are investigated in the quark-meson coupling (QMC) model. The QMC model is based on mean-field description of nonoverlapping spherical bags bound by self-consistent exchange of scalar and vector mesons. The predictions of this model are compared with quantum hadrodynamic (QHD) model calibrated to reproduce identical nuclear matter saturation properties. By employing a density dependent bag constant through direct coupling to the scalar field, the QMC model is found to exhibit identical properties as QHD near saturation density. Furthermore, this modified QMC model provides well-behaved and continuous solutions at high densities relevant to the core of neutron stars. Two additional strange mesons are introduced which couple only to the strange quark in the QMC model and to the hyperons in the QHD model. The constitution and structure of stars with hyperons in the QMC and QHD models reveal interesting differences. This suggests the importance of quark structure effects in the baryons at high densities.Comment: 28 pages, 10 figures, to appear in Physical Review

Nonlinear Integer Programming

Research efforts of the past fifty years have led to a development of linear integer programming as a mature discipline of mathematical optimization. Such a level of maturity has not been reached when one considers nonlinear systems subject to integrality requirements for the variables. This chapter is dedicated to this topic. The primary goal is a study of a simple version of general nonlinear integer problems, where all constraints are still linear. Our focus is on the computational complexity of the problem, which varies significantly with the type of nonlinear objective function in combination with the underlying combinatorial structure. Numerous boundary cases of complexity emerge, which sometimes surprisingly lead even to polynomial time algorithms. We also cover recent successful approaches for more general classes of problems. Though no positive theoretical efficiency results are available, nor are they likely to ever be available, these seem to be the currently most successful and interesting approaches for solving practical problems. It is our belief that the study of algorithms motivated by theoretical considerations and those motivated by our desire to solve practical instances should and do inform one another. So it is with this viewpoint that we present the subject, and it is in this direction that we hope to spark further research.Comment: 57 pages. To appear in: M. J\"unger, T. Liebling, D. Naddef, G. Nemhauser, W. Pulleyblank, G. Reinelt, G. Rinaldi, and L. Wolsey (eds.), 50 Years of Integer Programming 1958--2008: The Early Years and State-of-the-Art Surveys, Springer-Verlag, 2009, ISBN 354068274