Studies of genotoxicity and apoptosis using human lymphocytes or murine neuroblastoma cells exposed in vitro to radiofrequency fields characteristic of mobile phones

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.The aim of the study was to investigate whether non-thermal levels of radiofrequency (RF) fields, characteristic of some mobile phones, might be directly genotoxic when applied in vitro to unstimulated G0 or stimulated human lymphocytes. Also, the study aimed to investigate the possibility that RF fields might act epipigenetically when combined with x-rays, by modifying their effect when applied in vitro to G0 lymphocytes. In addition, the possibility of RF fields inducing apoptosis in murine neuroblastoma (N2a) cells was also examined. G0 lymphocytes from 4 donors were exposed for a total of 24 h to a continuous or an intermittent RF signal. The signals were 935 MHz GSM (Global System for Mobile Communication) Basic, 1800 MHz GSM Basic, 935 MHz continuous wave (CW) carrier frequency, and 935 MHz GSM Talk. Stimulated lymphocytes were exposed for a total of 48 h to intermittent 1800 MHz RF signals that were GSM Basic or the carrier frequency only. The RF fields used for the 24 h exposure of N2a cells were all at 935 MHz and consisted of GSM Basic, GSM Talk and a CW signal. The chosen Specific energy Absorption values of the signals were either 1 or 2 W/kg. These values are near the upper limit of actual energy absorbed in localised tissue by a person from some mobile phones. The field was applied to G0 human lymphocytes either alone or combined with an exposure to 1 Gy x-rays given immediately before or after the RF field. A dose of 4 Gy x-rays was used as a positive control for apoptosis induction in N2a cells and in the study with stimulated lymphocytes no x-rays were used. The lymphocytes were assayed by several standard methods to demonstrate genotoxicity. Unstable chromosome aberrations (stimulated lymphocytes and those exposed in G0), sister chromatid exchanges (SCE) and cytokinesis blocked micronuclei (MN) (lymphocytes exposed in G0). In addition the SCE and MN assays allowed nuclear division indices (NDI) to be calculated as NDI defines the cell cycle progression of lymphocytes after PHA stimulation and how this might be affected by RF exposure. N2a cells were assessed by fluorescence microscopy for levels of apoptosis at a number of time points post RF field or x-ray exposure, between 0 and 48 h. Three independent assays that detect different stages of the apoptotic pathway were used, the Annexin V binding, caspase activation and in situ end labelling. By comparison with appropriate sham exposed samples no effect of RF fields alone could be found in G0 or PHA stimulated lymphocytes exposed in vitro. Also, RF fields did not modify any measured effects of x-rays either given before or after RF exposure. No statistically significant difference in apoptosis levels were observed between RF exposed and sham exposed N2a cells in either a proliferating or differentiated state for any assay at any time point post exposure

Macro stress testing with a macroeconomic credit risk model: Application to the French manufacturing sector.

The aim of this paper is to build and estimate a macroeconomic model of credit risk for the French manufacturing sector. This model is based on Wilson's CreditPortfolioView model (1997a, 1997b); it enables us to simulate loss distributions for a credit portfolio for several macroeconomic scenarios. We implement two simulation procedures based on two assumptions relative to probabilities of default (PDs): in the first procedure, firms are assumed to have identical default probabilities; in the second, individual risk is taken into account. The empirical results indicate that these simulation procedures lead to quite different loss distributions. For instance, a negative one standard deviation shock on output leads to a maximum loss of 3.07% of the financial debt of the French manufacturing sector, with a probability of 99%, under the identical default probability hypothesis versus 2.61% with individual default probabilities.macro stress test ; credit risk model ; loss distribution.

Les technologies de la responsabilité sociétale ou l'invention du manager responsable: le cas Lafarge.

Les exigences de la société en matière de responsabilité sociétale portent sur la transparence et l’innocuité des activités de l’entreprise : l’usine que l’on construit ou la carrière que l’on exploite se doivent d’être invisibles, inodores, insonores. L’entreprise se doit de montrer qu’elle respecte ces exigences car c’est ainsi qu’elle gagne en légitimité. Il lui faut donc rendre visible l’invisible, tracer et matérialiser les « flux » de légitimité entre elle et ses parties prenantes. Les technologies de gestion qu’elle mobilise à cette occasion façonnent un manager potentiellement responsable.Social requirements concerning corporate social responsibility focus on transparency and harmlessness of firm activities : a factory or a quarry must be invisible, odorless, and silent. Firms must show that they respect those requirements in order to gain legitimacy. They must change invisibility into visibility, trace legitimacy flows between them and the society. Thus, firms use managerial technologies potentially able to create the accountable manager.Corporate social responsibility; Responsabilité sociétale; Développement durable; Néo-institutionalisme;

Tax Concessions and Investment Behaviour

The Government of Pakistan, like many other developing countries, has opted for tax holidays as an important fiscal measure to encourage rapid industrialisation in the backward areas. This concession is also supplemented by several other economic and non-economic measures including import duty, and depreciation allowances. Mintz (1990) discusses the efficacy of tax holidays in the presence of accelerated depreciation allowances concludes that tax holidays which are designed to increase capital formation may end up penalising capital formation. Mintz’s (1990) conclusion is based on the assumption that if the assets are long-lived, and the income tax system allows deductibility of accelerated depreciation but cannot be deferred, then the tax holidays, by preventing depreciation deduction in the early period may actually penalise investment during the tax holiday period. If on the other hand the depreciation allowance is deferred till the end of tax holiday period, the tax system is genuinely generous and provides a real incentive for capital formation

Tax Concessions and Investment Behaviour

The Government of Pakistan, like many other developing countries, has opted for tax holidays as an important fiscal measure to encourage rapid industrialisation in the backward areas. This concession is also supplemented by several other economic and non-economic measures including import duty, and depreciation allowances. Mintz (1990) discusses the efficacy of tax holidays in the presence of accelerated depreciation allowances concludes that tax holidays which are designed to increase capital formation may end up penalising capital formation. Mintz’s (1990) conclusion is based on the assumption that if the assets are long-lived, and the income tax system allows deductibility of accelerated depreciation but cannot be deferred, then the tax holidays, by preventing depreciation deduction in the early period may actually penalise investment during the tax holiday period. If on the other hand the depreciation allowance is deferred till the end of tax holiday period, the tax system is genuinely generous and provides a real incentive for capital formation. In Pakistan the tax code are such that the firms in the tax holidays region are not allowed to claim or defer accelerated depreciation allowance but can claim normal depreciation allowance only after the expiry of tax holidays period. Whereas the firms in developed areas can claim both accelerated (25 percent) and normal depreciation allowances (10 percent) annually. Import duty concession is given for most of the underdeveloped areas and few of the developed areas. These different sets of incentives affects the cost of capital and hence investment differently. The purpose of the present paper is to see these effects by computing the cost of capital for developed and under developed areas. This will help us to examine whether the tax holidays as an incentive is effective or act as a barrier to claim other generous concession like the depreciation allowance.

Bias for consonantal information over vocalic information in 30-month-olds: cross-linguistic evidence from French and English.

Using a name-based categorization task, Nazzi found in 2005 that French-learning 20-month-olds can make use of one-feature consonantal contrasts between new labels but fail to do so with one-feature vocalic contrasts. This asymmetry was interpreted as developmental evidence for the proposal that consonants play a more important role than vowels at the lexical level. In the current study using the same task, we first show that by 30 months French-learning infants can make use of one-feature vocalic contrasts (e.g., /pize/-/pyze/). Second, we show that in a situation where infants must neglect either a consonantal one-feature change or a vocalic one-feature change (e.g., match a /pide/ with either a /tide/ or a /pyde/), both French- and English-learning 30-month-olds choose to neglect the vocalic change rather than the consonantal change. We argue that these results suggest that by 30 months of age, infants still give less weight to vocalic information than to consonantal information in a lexically related task even though they are able to process fine vocalic information

The second gamma-H2AX assay inter-comparison exercise carried out in the framework of the European biodosimetry network (RENEB)

Purpose: Within the EU RENEB project, seven laboratories have taken part in training and harmonisation activities to strengthen triage gamma H2AX-based radiation exposure assessment. This has culminated in a second triage biodosimetry exercise. Materials and methods: Whole blood and separated lymphocyte samples were homogenously irradiated with 60Co gamma rays at 0.5, 2.5 (blind samples), 0 and 2 Gy (reference samples). Following post-exposure incubations of 4 and 24 h, 16 samples were shipped on ice packs to each partner. The samples were stained and scored for gamma-H2AX foci, using manual and/or automated fluorescence microscope scoring strategies. Dose estimates were obtained and used to assign triage categories to the samples. Results: Average dose estimates across all the laboratories correlated well with true doses. The most accurate assignment of triage category was achieved by manual scoring of the 4-h blood and lymphocyte samples. Only three samples out of a total of 46 were miscategorized in a way that could have adversely effected the clinical management of a radiation casualty. Conclusions: This inter-comparison exercise has demonstrated that following a recent acute radiation exposure, the gamma-H2AX assay could be a useful triage tool that can be successfully applied across a network of laboratories

Caractérisation des flux d'altération des contextes orogéniques en milieu tropical. Cas des bassins andins et d'avant pays de l'Amazone

L'évaluation du bilan d'altération des chaînes orogéniques et l'identification des paramètres de contrôle de ces processus est une question majeure dans l'étude du cycle du carbone sur le long terme. L'objectif de cette recherche est de mesurer les flux d'altération des bassins andins (deuxième chaîne mondiale après l'Himalaya) et d'avant-pays de l'Amazone (premier fleuve mondial) et de discuter de leurs variabilités en fonction des caractéristiques géographiques de ces bassins (climat, lithologie, couverture végétale, érosion). Ces flux d'altération ont été estimés à partir de l'acquisition à haute résolution temporelle et spatiale de données hydrochimiques (élément majeurs) et hydrologiques dans les réseaux de mesure PHICAB, HIBAM et ORE-HYBAM. Les bassins andins et d'avant-pays contrôlent près de 70% de la production du flux dissous de l'Amazone. L'altération des carbonates et des évaporites dans les bassins du Marañón et de l'Ucayali expliquent près de 70% de cette contribution. La variabilité spatiale des flux dissous est au premier ordre contrôlée par la variabilité de l'écoulement et par la nature lithologique du bassin considéré (carbonates / silicates). A l'exception des produits de dissolution des évaporites, la variabilité temporelle du flux de production de matières dissoutes est au premier ordre contrôlée par la variabilité hydrologique. La variabilité spatiale des taux d'altération des silicates n'est pas associée à celle des taux d'érosion dans les domaines andins. En normalisant par l'écoulement, l'intensité de production de matières dissoutes des zones de sédimentation actuelles (correspondant aux bassins d'avant-pays en subsidence du Madeira) est plus élevée que celle des zones d'avant-pays en érosion (Napo). La consommation de CO2 atmosphérique par altération des silicates (CO2 sil) des bassins andins et d'avant-pays représente 50-73% de celle de l'Amazone. La plaine du Solimões constitue un puits de CO2 sil significatif à l'échelle du bassin. Le flux de consommation de CO2 sil des bassins andins et d'avant-pays est équivalent à celui de l'Himalaya pour une surface deux fois plus faible et pour un débit spécifique deux fois plus important. Ce résultat met en évidence le rôle prédominant du climat dans la consommation de CO2 sil des chaines de montagnes tropicales. Par ailleurs, sur 80% du bassin de l'Amazone, l'intensité d'altération des silicates, indépendamment de leur teneur en éléments mobiles, est contrôlée par la variabilité spatiale de l'écoulement.The weathering flux estimation of orogenic belts and the identification of critical parameters that control these processes is a major question in the study of the long term carbon cycle. The objective of this research is to estimate the weathering of the Andean (the second largest orogenic belt after Himalaya) and foreland basins of the Amazon (the world's largest river) and to discuss variability according to geographical characteristics (climate, vegetation cover, lithology, erosion). The weathering fluxes of the Andean and foreland parts of the Amazon basin were estimated at high time and spatial resolution scales in the PHICAB, HIBAM and ORE-HYBAM frameworks. The Andean and foreland basins control the production of around 70% of the Amazon dissolved load. The carbonates and evaporites weathering in Marañón and Ucayali basins contribute approximately 70% of the total. The first order dissolved load spatial variability is controlled by the runoff and lithology (carbonates/silicates) variability. With the exception of the evaporites dissolution load products, the temporal variability of the dissolved load is firstly controlled by the hydrological variability. The silicate weathering variability in the Andean domain is not associated with the erosion rates variability. The dissolved rates are somewhat higher in the recent sedimentation areas (which correspond to Madeira subsidence foreland areas) than those calculated in foreland areas subjected to erosion if we normalize by the runoff (Napo). The atmospheric CO2 consumption derived from silicate weathering (CO2 sil) of the Andes and Foreland part represents 50-73% of the total CO2 sil budget of the Amazon. The Solimões plain contributes significantly to the Amazon basin CO2 sil. The Upper Amazon's silicate CO2 consumption flux is commensurate with the Himalaya's basins for an area two times lower and a runoff value two times higher. This result points out the importance of the climate for the CO2 sil consumption by tropical orogenic belts. 80% of the Amazon basin silicate weathering intensity is controlled by the runoff spatial variability, independently of the mobil cation content