Report on a visit to Bangladesh to initiate a research project entitled improvements in the production of livestock products in peri-urban areas of cities in Asia

This project was established in 1995. It aims to characterise the market for livestock products, examine the outputs and efficiency of livestock production and marketing systems, determine the losses of livestock products in the systems and identify and analyse constraints to and opportunities for the increased supply of livestock products to urban markets

Report on a visit to Bangladesh to supervise the research students undertaking the research project entitled: Improvements in the production of livestock products in peri-urban areas of cities in Asia

D Silverside, J Sherington and N Marsland visited Bangladesh to clean and analyse data collected by research workers during a survey of approximately 100 villages in Sylhet, Mymensingh and Pabna. They assisted with the completion of the first phase of the project, which is to define the urban, peri-urban and rural areas of three study towns. Terms of reference also included the establishment of a work programme for phase 2 and the monitoring of the progress of the research workers. Phase 1 is now complete. The mauzas (small study areas of the towns) have now been defined according to a statistical technique based on census and primary data and may be classified as rural, peri-urban and urban. Phase 1 may now be written up by the researchers into a formal part for their PhD theses. A summary can be found in Appendix 3 of this report. Protocols for Phase 2 have now been established and both questionnaires and checklists of questions have been finalised. These can be found in the Appendix 4 of this report. To conduct the work, enumerators will be required. Their numbers have been established and provision made for them in the budget. A system of data handling has been set up. The researchers have been trained in preparation of forms in Access and this, combined with earlier work on the computers will enable them to enter, manipulate and print out data for the project using up-to-date software packages. Para 25 refers. It was agreed that the researchers will be supervised on a regular basis by their BAU professors. During these supervisory sessions, researchers and professors will discuss project activities, outputs and problems. Communicate by Email with NRI in UK will take place every two weeks. Para 11 refers. A work programme and schedule was left in Bangladesh to be completed before the next NRI team visit. This will take place in October/November 1997. The team will include a socio-economist and computer modeller. Para 27 refers

Quality perceptions of parboiled rice marketed in Sri Lanka (NRI Bulletin 74)

A study was made of the parboiled rice market in Sri Lanka. Rice was obtained from commercial processors, objectively assessed for quality, then evaluated by wholesale traders. Statistical analysis showed that the objective measurement of colour was significant in pricing, together with foreign matter, moisture content and damaged grain. The study will provide information for processors wishing to raise the quality of their products

Electronic Structure, Local Moments and Transport in Fe_2VAl

Local spin density approximation calculations are used to elucidate electronic and magnetic properties of Heusler structure Fe_2VAl. The compound is found to be a low carrier density semimetal. The Fermi surface has small hole pockets derived from a triply degenerate Fe derived state at Gamma compensated by an V derived electron pocket at the X point. The ideal compound is found to be stable against ferromagnetism. Fe impurities on V sites, however, behave as local moments. Because of the separation of the hole and electron pockets the RKKY interaction between such local moments should be rapidly oscillating on the scale of its decay, leading to the likelihood of spin-glass behavior for moderate concentrations of Fe on V sites. These features are discussed in relation to experimental observations of an unusual insulating state in this compound.Comment: 16 pages, RevTeX, 5 figure

Semi-fermionic representation for spin systems under equilibrium and non-equilibrium conditions

We present a general derivation of semi-fermionic representation for spin operators in terms of a bilinear combination of fermions in real and imaginary time formalisms. The constraint on fermionic occupation numbers is fulfilled by means of imaginary Lagrange multipliers resulting in special shape of quasiparticle distribution functions. We show how Schwinger-Keldysh technique for spin operators is constructed with the help of semi-fermions. We demonstrate how the idea of semi-fermionic representation might be extended to the groups possessing dynamic symmetries (e.g. singlet/triplet transitions in quantum dots). We illustrate the application of semi-fermionic representations for various problems of strongly correlated and mesoscopic physics.Comment: Review article, 40 pages, 11 figure

Impact of Human FcγR Gene Polymorphisms on IgG-Triggered Cytokine Release: Critical Importance of Cell Assay Format

Monoclonal antibody (mAb) immunotherapy has transformed the treatment of allergy, autoimmunity, and cancer. The interaction of mAb with Fc gamma receptors (FcγR) is often critical for efficacy. The genes encoding the low-affinity FcγR have single nucleotide polymorphisms (SNPs) and copy number variation that can impact IgG Fc:FcγR interactions. Leukocyte-based in vitro assays remain one of the industry standards for determining mAb efficacy and predicting adverse responses in patients. Here we addressed the impact of FcγR genetics on immune cell responses in these assays and investigated the importance of assay format. FcγR genotyping of 271 healthy donors was performed using a Multiplex Ligation-Dependent Probe Amplification assay. Freeze-thawed/pre-cultured peripheral blood mononuclear cells (PBMCs) and whole blood samples from donors were stimulated with reagents spanning different mAb functional classes to evaluate the association of FcγR genotypes with T-cell proliferation and cytokine release. Using freeze-thawed/pre-cultured PBMCs, agonistic T-cell-targeting mAb induced T-cell proliferation and the highest levels of cytokine release, with lower but measurable responses from mAb which directly require FcγR-mediated cellular effects for function. Effects were consistent for individual donors over time, however, no significant associations with FcγR genotypes were observed using this assay format. In contrast, significantly elevated IFN-γ release was associated with the FCGR2A-131H/H genotype compared to FCGR2A-131R/R in whole blood stimulated with Campath (p ≤ 0.01) and IgG1 Fc hexamer (p ≤ 0.05). Donors homozygous for both the high affinity FCGR2A-131H and FCGR3A-158V alleles mounted stronger IFN-γ responses to Campath (p ≤ 0.05) and IgG1 Fc Hexamer (p ≤ 0.05) compared to donors homozygous for the low affinity alleles. Analysis revealed significant reductions in the proportion of CD14hi monocytes, CD56dim NK cells (p ≤ 0.05) and FcγRIIIa expression (p ≤ 0.05), in donor-matched freeze-thawed PBMC compared to whole blood samples, likely explaining the difference in association between FcγR genotype and mAb-mediated cytokine release in the different assay formats. These findings highlight the significant impact of FCGR2A and FCGR3A SNPs on mAb function and the importance of using fresh whole blood assays when evaluating their association with mAb-mediated cytokine release in vitro. This knowledge can better inform on the utility of in vitro assays for the prediction of mAb therapy outcome in patients

Use of survival analysis methods with cattle reproductive performance data

The paper gives an example of the use of survival analysis to examine time to conception for a breed by nutrition factorial experiment and the relationship between time to conception and body weight. The example is made complicated by confounding between the treatments and the weight of animals at the beginning of mating. The paper first describes the experiment briefly. It then describes an analysis of simple conception rate using logistic models. Survival analysis is then outlined and the proportional hazards model is used to analyse time to conception

Rapid assessment methods for stored maize cobs: weight losses due to insect pests

This paper describes a new method for the assessment of weight loss due to insect pests in stored maize cobs. The method involves scoring each cob in the sample on a visual damage scale and then using a simple equation to estimate overall sample weight loss. The coefficients in the equation are determined in advance of field work by calibrating the visual scale against a laboratory loss assessment technique. The visual scale method was found to be rapid, simple and had many advantages for on-farm work. Precision of the results was shown to be similar to that of existing weight loss assessment methods

A method for estimating sampling variances of predicted probabilities from maximum likelihood estimates in logit response function

The maximum likelihood parameters estimated in logistic analysis are in terms of a transformation of the original response variable and, although inferences are easily made about the sources of variation in the linearized model using standard procedures applied in regression analysis, the variance-covariance structure of the predicted probabilities obtained following back-transformation of logits is complex and estiamtion of sampling variances normally requires inversion of matrices and taking derivatives of the inverse of the link function evaluated at each prediction point. This paper presents a method for estimating sampling variances of such predicted probabilities without the need to invert any matrix or take derivatives of the link function. The method is based on the assumption that the exponent of a linear function of the logits is lognormal. It is demonstrated by way of a numerical example that this approximation is not different from the more complex methods applied by such software as SAS and GENSTAT