Study to investigate and improve the zinc electrode for spacecraft electrochemical cells Final report, 30 May 1966 - 30 Jun. 1967

Zincate diffusivity in alkaline electrolyte determined as function of potassium hydroxide concentration and temperatur

An Agent-Based Simulation of Rental Housing Markets

We simulate a closed rental housing market with search and matching frictions, in which both landlord and tenant agents are imperfectly informed. Homogeneous landlords set rents to maximise revenue, using information on the market to estimate the relationship between posted rent and time-on-the-market (TOM). Tenants, heterogeneous in income, engage in undirected search accepting residences based on their idiosyncratic tastes for housing and a disagreement point derived from information on the distribution of offers. The steady state to which the simulation evolves shows price dispersion, nonzero search times and vacancies.The main results concern the effects of increasing information on either side of the market. When tenants see a greater percentage of the distribution of offers, tenants learn to refuse high rents and so the population rises and tenants' utilities rise as does overall welfare. Conversely, when landlords have less information, their utility can rise as over estimations in best posting rent move the market to higher rents.Real estate; Rental markets; Search; Information; Simulation; Multi-agent systems

Interactions Localisations Transport. Projet ILOT – Phase I. Rapport final pour la DRAST

Le projet ILOT consiste à appliquer la modélisation multi-agents aux rapports entre mobilité locale et transformation des espaces dans les aires urbaines. Il vise à développer dans un premier temps un ensemble de "briques" théoriques susceptibles de représenter de manière pertinente l'émergence de comportements collectifs en matière de rythmes temporels d'activités et de localisation. A plus long terme, ces "briques" théoriques seront le matériau de base pour élaborer des modèles plus appliqués, susceptibles d'être confrontés à des situations réelles.L'objectif à long terme de cette recherche consiste à réaliser des outils opérationnels, pour la recherche dans un premier temps et pour l'application dans un second temps, qui permettent de comprendre et d'analyser l'interaction entre la mobilité et la localisation dans les aires urbaines.Trois étapes ont été préalables identifiées qui semblent pertinentes :- l'exploration théorique de l'émergence de comportements "stylisés" de rythmes temporels et de localisation d'activités à travers une "ville-modèle",- le couplage de modèles éprouvés dans les domaines respectifs du transport et de la localisation, en particulier les modèles applicables à des problèmes pratiques,- l'identification et la résolution des obstacles informatiques relatifs à la simulation, à la collecte des données et à l'analyse des résultats de ces modèles

Interactions Localisations Transport. Projet ILOT – Phase I. Rapport final pour la DRAST

Le projet ILOT consiste à appliquer la modélisation multi-agents aux rapports entre mobilité locale et transformation des espaces dans les aires urbaines. Il vise à développer dans un premier temps un ensemble de "briques" théoriques susceptibles de représenter de manière pertinente l'émergence de comportements collectifs en matière de rythmes temporels d'activités et de localisation. A plus long terme, ces "briques" théoriques seront le matériau de base pour élaborer des modèles plus appliqués, susceptibles d'être confrontés à des situations réelles.L'objectif à long terme de cette recherche consiste à réaliser des outils opérationnels, pour la recherche dans un premier temps et pour l'application dans un second temps, qui permettent de comprendre et d'analyser l'interaction entre la mobilité et la localisation dans les aires urbaines.Trois étapes ont été préalables identifiées qui semblent pertinentes :- l'exploration théorique de l'émergence de comportements "stylisés" de rythmes temporels et de localisation d'activités à travers une "ville-modèle",- le couplage de modèles éprouvés dans les domaines respectifs du transport et de la localisation, en particulier les modèles applicables à des problèmes pratiques,- l'identification et la résolution des obstacles informatiques relatifs à la simulation, à la collecte des données et à l'analyse des résultats de ces modèles.modélisation multi-agents ; mobilité urbaine ; localisation des activités ; interactions localisations transport

Determinants of treatment-related paradoxical reactions during anti-tuberculosis therapy: a case control study

BACKGROUND: Inflammatory response following initial improvement with anti-tuberculosis (TB) treatment has been termed a paradoxical reaction (PR). HIV co-infection is a recognised risk, yet little is known about other predictors of PR, although some biochemical markers have appeared predictive. We report our findings in an ethnically diverse population of HIV-infected and uninfected adults. METHODS: Prospective and retrospective clinical and laboratory data were collected on TB patients seen between January 1999-December 2008 at four UK centres selected to represent a wide ethnic and socio-economic mix of TB patients. Data on ethnicity and HIV status were obtained for all individuals. The associations between other potential risk factors and PR were assessed in a nested case-control study. All PR cases were matched two-to-one to controls by calendar time and centre. RESULTS: Of 1817 TB patients, 82 (4.5 %, 95 % CI 3.6-5.5 %) were identified as having a PR event. The frequency of PR was 14.4 % (18/125; 95 % CI 8.2-20.6 %) and 3.8 % (64/1692; 2.9-4.7) for HIV-positive and HIV-negative individuals respectively. There were no differences observed in PR frequency according to ethnicity, although the site was more likely to be pulmonary in those of black and white ethnicity, and lymph node disease in those of Asian ethnicity. In multivariate analysis of the case-control cohort, HIV-positive patients had five times the odds of developing PR (aOR = 5.05; 95 % CI 1.28-19.85, p = 0.028), whilst other immunosuppression e.g. diabetes, significantly reduced the odds of PR (aOR = 0.01; 0.00-0.27, p = 0.002). Patients with positive TB culture had higher odds of developing PR (aOR = 6.87; 1.31-36.04, p = 0.045) compared to those with a negative culture or those in whom no material was sent for culture. Peripheral lymph node disease increased the odds of a PR over 60-fold 4(9.60-431.25, p < 0.001). CONCLUSION: HIV was strongly associated with PR. The increased potential for PR in people with culture positive TB suggests that host mycobacterial burden might be relevant. The increased risk with TB lymphadenitis may in part arise from the visibility of clinical signs at this site. Non-HIV immunosuppression may have a protective effect. This study highlights the difficulties in predicting PR using routinely available demographic details, clinical symptoms or biochemical markers

Spectral catalogue of bright gamma-ray bursts detected with the BeppoSAX/GRBM

The emission process responsible for the so-called "prompt" emission of gamma-ray bursts is still unknown. A number of empirical models fitting the typical spectrum still lack a satisfactory interpretation. A few GRB spectral catalogues derived from past and present experiments are known in the literature and allow to tackle the issue of spectral properties of gamma-ray bursts on a statistical ground. We extracted and studied the time-integrated photon spectra of the 200 brightest GRBs observed with the Gamma-Ray Burst Monitor which flew aboard the BeppoSAX mission (1996-2002) to provide an independent statistical characterisation of GRB spectra. The spectra were fit with three models: a simple power-law, a cut-off power law or a Band function. The typical photon spectrum of a bright GRB consists of a low-energy index around 1.0 and a peak energy of the nuFnu spectrum E_p~240 keV in agreement with previous results on a sample of bright CGRO/BATSE bursts. Spectra of ~35% of GRBs can be fit with a power-law with a photon index around 2, indicative of peak energies either close to or outside the GRBM energy boundaries. We confirm the correlation between E_p and fluence, with a logarithmic dispersion of 0.13 around the power-law with index 0.21+-0.06. The low-energy and peak energy distributions are not yet explained in the current literature. The capability of measuring time-resolved spectra over a broadband energy range, ensuring precise measurements of parameters such as E_p, will be crucial for future experiments (abridged).Comment: 28 pages, 20 figures, 3 tables, accepted to A&

Electrical stimulation devices for the prevention of venous thromboembolism: Preliminary studies of physiological efficacy and user satisfaction.

Introduction: Electrical stimulation could provide an alternative method for preventing venous thromboembolism in stroke patients. The purpose of this preliminary study was to explore the effects of electrical stimulation and intermittent pneumatic compression on enhancing lower limb venous return in healthy and chronic stroke patients and also to evaluate patient and nurse satisfaction. Methods: We investigated the effectiveness of two electrical stimulation devices: Geko (Firstkind Ltd, High Wycombe, UK) and Orthopaedic Microstim 2V2 (Odstock Medical Ltd, Salisbury, UK); and one intermittent pneumatic compression device: Huntleigh Flowstron Universal (Huntleigh Healthcare Ltd, Cardiff, UK). We recruited 12 healthy and 5 chronic stroke participants. The devices were fitted sequentially, and Doppler ultrasound measurements were taken. Eight patients and nurses were also recruited for a separate usability evaluation. Results: The electrical stimulation devices emulated the blood flow characteristics of intermittent pneumatic compression in both healthy and stroke participants provided that the intensity of electrical stimulation was sufficient. Patients and nurses also felt that the electrical stimulation devices were acceptable. Conclusions: Electrical stimulation may offer benefit as an alternative method for venous thromboembolism prevention in stroke patients. The apparent benefit is sufficient to warrant further investigation in a full powered randomised controlled trial

Lack of Support for the Genes by Early Environment Interaction Hypothesis in the Pathogenesis of Schizophrenia

Ursini et al reported recently that the liability of schizophrenia explained by a polygenic risk score (PRS) derived from the variants most associated with schizophrenia was increased 5-fold in individuals who experienced complications during pregnancy or birth. Follow-up gene expression analysis showed that the genes mapping to the most associated genetic variants are highly expressed in placental tissues. If confirmed, these findings will have major implications in our understanding of the joint effect of genes and environment in the pathogenesis of schizophrenia. We examined the interplay between PRS and obstetric complications (OCs) in 5 independent samples (effective N = 2110). OCs were assessed with the full or modified Lewis-Murray scale, or with birth weight < 2.5 kg as a proxy. In a large cohort we tested whether the pathways from placenta-relevant variants in the original report were associated with case-control status. Unlike in the original study, we did not find significant effect of PRS on the presence of OCs in cases, nor a substantial difference in the association of PRS with case-control status in samples stratified by the presence of OCs. Furthermore, none of the PRS by OCs interactions were significant, nor were any of the biological pathways, examined in the Swedish cohort. Our study could not support the hypothesis of a mediating effect of placenta biology in the pathway from genes to schizophrenia. Methodology differences, in particular the different scales measuring OCs, as well as power constraints for interaction analyses in both studies, may explain this discrepancy