NAIADQ, a computer program for calculating reactivity transients in low power experimental water reactors.

The computer code NAIADQ is designed to simulate the course and consequences of non-destructive reactivity accidents in low power experimental water-cooled reactor cores fuelled with metal plate elements. It is a coupled neutron kinetics-hydrodynamics-heat transfer code which uses point kinetics and one-dimensional thermohydraulic equations. Nucleate boiling which occurs at the fuel surface during transients is modelled by the growth of a superheated layer of water in which vapour is generated at a non-equilibrium rate. It is assumed that this vapour is formed at its saturation temperature and that it mixes homogeneously with the water in this layer. The code is written in FORTRAN IV and has been programmed to run as a catalogued procedure on an IBM operating system such as MVT or MVS with facility for the inclusion of user routines

Calculation of power transients for the SPERT II nuclear reactor core with inclusion of nucleate boiling of the coolant.

The published data for a series of power transients initiated in the water-cooled core of the SPERT II nuclear reactor were investigated to determine the magnitude of the reactivity feedback effects arising from heat transfer and vapour void formation during subcooled nucleate boiling. This was done using the NAIADQ computer code which describes the thermohydraulic behaviour of the water coolant in the fuelled region of the core in terms of a set of one-dimensional linear finite difference equations. Nucleate boiling at the fuel surface is represented as an expanding superheated layer of water in which saturated vapour is assumed to be uniformly generated at a non-equilibrium rate. The simulation of the transients all of which were initiated at ambient temperature necessitated the calculation of heat transfer from the fuel to the water coolant in the regimes of conduction convection and surface boiling for a wide range of coolant flow rates during rapidly changing reactor power levels. The calculated variations in the reactor power with time during the transients are in good agreement with the measured data over the range of conditions tested in the experimental investigations

Variation of neutron yield from a titanium-tritide target during deuterium beam bombardment.

In the laboratory simulation of D-T fusion breeder blankets 14 MeV neutrons are produced by the bombardment of a titanium-tritide target with deuterium ions using accelerating voltages up to 500 keV and beam currents ranging from micro to milliamperes. For the accurate determination of tritium breeding ratios in the experimental assemblies an absolute determination of the total neutron yield over the irradiation period is required. The theoretical and experimental methods used to determine the ion composition of the deuterium beam the changing absolute yields and energy distributions of the neutrons emitted from the target during prolonged irradiation are described using the AAEC 14 MeV neutron generator as a typical example. Analysis of the measured data identified two ion species in the beam of the neutron generator. It was shown that after a 21-hour irradiation of the target with a 250 mu A beam (18.5C) at 200 kV the neutron output from the D-T reaction dropped from an initial value of 2 x 10 1 0 to 4 x 10 8 neutrons per second. The integrated neutron output over this period was estimated to be 2.05 x 10 14 of which about 24 per cent originated from the interaction of monatomic ions and 75 per cent from diatomic ions; less than one per cent arose from D-D reaction

Theoretical investigation of absolute neutron detection.

A survey was made of the detection systems classified as 'flat response' in order to establish their use in high accuracy measurements of absolute neutron intensities for a wide range of neutron sources. Two detection systems involving neutron moderation in either graphite of an hydrogenous material were selected as having the most suitable characteristics. Numerical solutions of the neutron transport equations for these systems were computed to determine the conditions required to produce minimum variation of efficiency with energy. It was shown that, with the suitable choice of moderator composition and size, it should be possible to reduce these errors to less than one per cent over the energy range 100 eV to 4 MeV

A Personal Construct Psychology based investigation into a Product Service System for renting pushchairs to consumers

This is the peer-reviewed version of the following article: Maurizio Catulli and Nick Reed, ‘A Personal Construct Psychology Based Investigation Into a Product Service System for Renting Pushchairs to Consumers’, Business Strategy and the Environment, Vol. 26(5): 656-671, February 2017, which has been published in final form at DOI: 10.1002/bse.1944. Under embargo. Embargo end date: 1 February 2019. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.This paper explores how consumers construe a Product Service System (PSS) for the supply of pushchairs. A PSS is a system of products, services, networks of actors and supporting infrastructure designed to be more sustainable than traditional business models. PSS face an implementation challenge in consumer markets and this case based research explores some reasons for this. The study applies Personal Construct Psychology (in particular, Repertory Grid Technique) which has not previously been used in relation to researching PSS. Results suggest that PSS might be difficult to implement in relation to pushchairs. Renting pre-used equipment may meet resistance because of a perceived risk that acquisition by this means might endanger infants. Participants in the study construed buying new products from specialist infant product shops as being the best way of acquiring them. Accordingly PSS providers may, for instance, have to implement certified quality assurance processes in order to reassure consumers.Peer reviewedFinal Accepted Versio

The Importance of pH in Regulating the Function of the Fasciola hepatica Cathepsin L1 Cysteine Protease

The helminth parasite Fasciola hepatica secretes cathepsin L cysteine proteases to invade its host, migrate through tissues and digest haemoglobin, its main source of amino acids. Here we investigated the importance of pH in regulating the activity and functions of the major cathepsin L protease FheCL1. The slightly acidic pH of the parasite gut facilitates the auto-catalytic activation of FheCL1 from its inactive proFheCL1 zymogen; this process was ∼40-fold faster at pH 4.5 than at pH 7.0. Active mature FheCL1 is very stable at acidic and neutral conditions (the enzyme retained ∼45% activity when incubated at 37°C and pH 4.5 for 10 days) and displayed a broad pH range for activity peptide substrates and the protein ovalbumin, peaking between pH 5.5 and pH 7.0. This pH profile likely reflects the need for FheCL1 to function both in the parasite gut and in the host tissues. FheCL1, however, could not cleave its natural substrate Hb in the pH range pH 5.5 and pH 7.0; digestion occurred only at pH≤4.5, which coincided with pH-induced dissociation of the Hb tetramer. Our studies indicate that the acidic pH of the parasite relaxes the Hb structure, making it susceptible to proteolysis by FheCL1. This process is enhanced by glutathione (GSH), the main reducing agent contained in red blood cells. Using mass spectrometry, we show that FheCL1 can degrade Hb to small peptides, predominantly of 4–14 residues, but cannot release free amino acids. Therefore, we suggest that Hb degradation is not completed in the gut lumen but that the resulting peptides are absorbed by the gut epithelial cells for further processing by intracellular di- and amino-peptidases to free amino acids that are distributed through the parasite tissue for protein anabolism

Prevalence of Hepatitis E Virus in Swine Fed on Kitchen Residue

The aim of this study was to investigate the prevalence of swine hepatitis E virus (HEV) in pigs fed different feedstuffs (kitchen residue or mixed feeds) and genetic identification of HEV isolated in Hebei province, China. Serum and fecal samples were collected from adult swine. Anti-HEV antibody was evaluated by double sandwich antigen enzyme immunoassay. HEV RNA was extracted from fecal samples and amplified by nested RT-PCR. The reaction products were sequenced, and the sequence analyzed. Virus-like particles were distinguishable by negative staining in the electron microscope. Histopathological observation and immunohistochemical localization were used in the animal models. Overall, the anti-HEV positive percentage of serum samples from pigs fed on kitchen residue was 87.10% (27/31), and 53.06% (130/245) from pigs fed on complete feed. The HEV RNA positivity rate of fecal samples from pigs fed on kitchen residue was 61.54% (8/13), but zero for pigs fed on complete feed. Sequence analysis of these eight samples and comparison with the published sequence showed that there were eight groups that belonged to genotype 4 d and the nucleotide identity was 95.6–99.3%. swHE11 is most closely related to strain CCC220, and the other seven HEV isolates were most closely related to strains swGX40, SwCH189 and V0008ORF3, which are isolates from human and pigs. Histopathological observation showed that there was liver damage in the experimental group, and immunohistochemistry indicated that the HEV antigens were strongly positive at 7 days after infection. The results demonstrated that the prevalence of HEV in pigs fed on kitchen residue was higher than in those fed on complete feed (P<0.05)

Co-ordinated Gene Expression in the Liver and Spleen during Schistosoma japonicum Infection Regulates Cell Migration

Determining the molecular events induced in the spleen during schistosome infection is an essential step in better understanding the immunopathogenesis of schistosomiasis and the mechanisms by which schistosomes modulate the host immune response. The present study defines the transcriptional and cellular events occurring in the murine spleen during the progression of Schistosoma japonicum infection. Additionally, we compared and contrasted these results with those we have previously reported for the liver. Microarray analysis combined with flow cytometry and histochemistry demonstrated that transcriptional changes occurring in the spleen were closely related to changes in cellular composition. Additionally, the presence of alternatively activated macrophages, as indicated by up-regulation of Chi3l3 and Chi3l4 and expansion of F4/80+ macrophages, together with enhanced expression of the immunoregulatory genes ANXA1 and CAMP suggests the spleen may be an important site for the control of S. japonicum-induced immune responses. The most striking difference between the transcriptional profiles of the infected liver and spleen was the contrasting expression of chemokines and cell adhesion molecules. Lymphocyte chemokines, including the homeostatic chemokines CXCL13, CCL19 and CCL21, were significantly down-regulated in the spleen but up-regulated in the liver. Eosinophil (CCL11, CCL24), neutrophil (CXCL1) and monocyte (CXCL14, CCL12) chemokines and the cell adhesion molecules VCAM1, NCAM1, PECAM1 were up-regulated in the liver but unchanged in the spleen. Chemokines up-regulated in both organs were expressed at significantly higher levels in the liver. Co-ordinated expression of these genes probably contributes to the development of a chemotactic signalling gradient that promotes recruitment of effector cells to the liver, thereby facilitating the development of hepatic granulomas and fibrosis. Together these data provide, for the first time, a comprehensive overview of the molecular events occurring in the spleen during schistosomiasis and will substantially further our understanding of the local and systemic mechanisms driving the immunopathogenesis of this disease

Adaptive and Innate Immune Responses in Autism: Rationale for Therapeutic Use of Intravenous Immunoglobulin

Autism is a complex polygenic neurodevelopmental disorder characterized by deficits in communication and social interactions as well as specific stereotypical behaviors. Both genetic and environmental factors appear to contribute to the pathogenesis of autism. Accumulating data including changes in immune responses, linkage to major histocompatibility complex antigens, and the presence of autoantibodies to neural tissues/antigens suggest that the immune system plays an important role in its pathogenesis. In this brief review, we discuss the data regarding changes in both innate and adaptive immunity in autism and the evidence in favor of the role of the immune system, especially of maternal autoantibodies in the pathogenesis of a subset of patients with autism. The rationale for possible therapeutic use of intravenous immunoglobulin is also discussed

Exploring the views of young women and their healthcare professionals on dietary habits and supplementation practices in adolescent pregnancy: a qualitative study

Background: Nutrition is a modifiable factor affecting foetal growth and pregnancy outcomes. Inadequate nutrition is of particular concern in adolescent pregnancies with poor quality diet and competing demands for nutrients. The aim of this study was to explore knowledge and understanding of nutrition advice during adolescent pregnancy,and identify barriers and facilitators to dietary change and supplementation use in this vulnerable population. Methods: Semi-structured interviews were conducted with young women and key antenatal healthcare providers: midwives, family nurses and obstetricians. Doncaster, Manchester and London were chosen as sites offering different models of midwifery care alongside referral to the Family Nurse Partnership programme. Results: A total of 34 young women (adolescents aged 16–19 years) and 20 health professionals were interviewed. Young women made small changes to their dietary intake despite limited knowledge and social constraints. Supplementation use varied; the tablet format was identified by few participants as a barrier but forgetting to take them was the main reason for poor adherence. Health professionals provided nutrition information but often lack the time and resources to tailor this appropriately. Young women’s prime motivator was a desire to have a healthy baby; they wanted to understand the benefits of supplementation and dietary change in those terms. Conclusion: Pregnancy is a window of opportunity for improving nutrition but often constrained by social circumstances. Health professionals should be supported in their role to access education, training and resources which build their self-efficacy to facilitate change in this vulnerable population group beyond the routine care they provide