Time dependent entanglement properties, and other quantum-information aspects, of two-qubits systems interacting with an environment

Quantum systems usually suffer from unavoidable interactions with the environment. In most experiments, it is virtually impossible to isolate the system under study from the environment. It is thus imperative to study and understand how quantum systems interact with their surroundings. In the present study, I consider the evolution of quantum entanglement in a two-qubit system interacting with an environment in a regime where the non-Markovian effects are important. The present thesis is organized as follows: Chapter one is a general introduction to the thesis. In chapter two, some preliminary concepts that will be used in the subsequent chapters will be introduced and defined. These concepts include qubits, density matrix, Quantum entanglement and Entropic measures in quantum information. Ways to detect or quantify entanglement in a quantum system will also be discussed in the section on quantum entanglement. Chapter three will be about open quantum systems in general: concepts like master equations, Markovian quantum systems and non-Markovian quantum systems will be briefly reviewed. Chapter four will deal with time dependent entanglement features of two-qubit and multi-qubit systems interacting with an environment, basically all the results obtained in my study will be presented there. Some general conclusions will be drawn in chapter five. CopyrightDissertation (MSc)--University of Pretoria, 2010.Physicsunrestricte

Some entanglement features exhibited by two, three and four qubits interacting with an environment in a non-Markovian regime

We explore various aspects of the quantum entanglement dynamics of systems of two, three and four qubits interacting with an environment at zero temperature in a non-Markovian regime, as described by the paradigmatic model recently studied by Bellomo et al (2007 Phys. Rev. Lett. 99 160502). We consider important families of initial states for the alluded systems. The average, typical entanglement evolution associated with each of these families is determined, and its relation with the evolution of the global degree of mixedness of the multi-qubit system is explored. For three and four qubits we consider the family of initial states equivalent under local unitary transformations to the |GHZ〉 and |W〉 states, and compare their average behavior with the average behavior exhibited by initial maximally entangled two-qubit states. Furthermore, in the case of two qubits, the evolution of other manifestations of entanglement, related to measurable quantities, is also investigated. In particular, we consider the Mintert-Buchleitner concurrence lower bound and an entanglement indicator based upon the violation of local uncertainty relations.Fil: Hamadou Ibrahim, A.. University of Pretoria; SudáfricaFil: Plastino, Ángel Ricardo. Universidad de Granada; España. Universidad Nacional de La Plata; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; ArgentinaFil: Zander, C.. University of Pretoria; Sudáfric

Epidemiological, clinical and biological features of malaria among children in Niamey, Niger

BACKGROUND: Malaria takes a heavy toll in Niger, one of the world's poorest countries. Previous evaluations conducted in the context of the strategy for the Integrated Management of Childhood Illness, showed that 84% of severe malaria cases and 64 % of ordinary cases are not correctly managed. The aim of this survey was to describe epidemiological, clinical and biological features of malaria among <5 year-old children in the paediatric department of the National Hospital of Niamey, Niger's main referral hospital. METHODS: The study was performed in 2003 during the rainy season from July 25(th )to October 25(th). Microscopic diagnosis of malaria, complete blood cell counts and measurement of glycaemia were performed in compliance with the routine procedure of the laboratory. Epidemiological data was collected through interviews with mothers. RESULTS: 256 children aged 3–60 months were included in the study. Anthropometrics and epidemiological data were typical of a very underprivileged population: 58% of the children were suffering from malnutrition and all were from poor families. Diagnosis of malaria was confirmed by microscopy in 52% of the cases. Clinical symptoms upon admission were non-specific, but there was a significant combination between a positive thick blood smear and neurological symptoms, and between a positive thick blood smear and splenomegaly. Thrombopaenia was also statistically more frequent among confirmed cases of malaria. The prevalence of severe malaria was 86%, including cases of severe anaemia among < 2 year-old children and neurological forms after 2 years of age. Overall mortality was 20% among confirmed cases and 21% among severe cases. CONCLUSIONS: The study confirmed that malaria was a major burden for the National Hospital of Niamey. Children hospitalized for malaria had an underprivileged background. Two distinctive features were the prevalence of severe malaria and a high mortality rate. Medical and non-medical underlying factors which may explain such a situation are discussed

First Impact Assessment of Genotoxic Components in the Qatari Marine Environment

The Arabian Gulf is a semi-enclosed sea with very high evaporation and low discharge rates resulting in extreme saline and thermal conditions. Additionally the system is characterized by a weak hydrodynamic flushing resulting in pollutant build-up over time. As a result, compared to open marine systems, added stress imposed by pollutants is likely to have severe consequences. Qatar has witnessed a rapid expansion in coastal development, linked to its industrial and population growth in recent decades. While economically and socially valuable, the growth comes with an associated environmental cost and Qatar's marine environment now faces many pressures including eutrophication, inputs of domestic sewage, discharge of industrial waste and the resuspension of sediment due to coastal construction. Although the threats pose to biota inhabiting Qatar's marine environment are evident, their extent has yet to be fully assessed. A large percentage of contaminants in the aquatic environment consist of potentially (directly or indirectly) genotoxic, carcinogenic and mutagenic substances. A genotoxin can modify the genetic material at non lethal and non cytotoxic concentrations and has often belated effects which are significantly important at the population and community levels. Genotoxins have particularly high ecotoxicological relevance in situations of chronic exposure to low doses and to multiple contaminants (e.g. in case of PAHs rich tarballs arriving in the shorelines), raising he need to establish genotoxicological profiles of the ecosystems. Indeed several regulatory developments such as: EU - Marine Strategy Framework Directive, the or US - Environmental Protection Agency - Integrated Risk Information System have stressed explicitly on the need of the detection and assessment of potential carcinogenic and mutagenic toxicants using genotoxicity endpoints. The analysis of cytogenetic endpoints in organisms exposed to contaminants in their natural environment contributes significantly to the early detection of genotoxic damage. The relevance of cytogenetic parameters and atypical cytogenetic features, such as numerical chromosomal abnormalities, i.e. aneuploidy, have largely proven their relevance as alerting indicators of poor environmental health and relevant biomarkers for the early detection of environmental stressors. The use of marine invertebrates for in situ environmental assessment is a widely accepted method for identifying risks to the ecosystems. Moreover, at the DNA and chromosome levels they express qualitatively similar types of induced damage to that found in higher organism (e.g. numerical and structural chromosomal aberrations). In this study, we aimed to take a step towards Qatar's marine sustainability by assessing the health status of the marine environment, and providing early alerting symptoms of degradation, by having as specific objectives: i) to measure the levels, in abiotic (water, sediments) and a marine invertebrate model species, of various anthropogenic contaminants (metals, polycyclic aromatic hydrocarbons, (PAHs) and Total polyaromatic hydrocarbons (TPH) at 3 selected sites around the Qatari coast, ii) measure the biological response at the chromosome level, and iii) determine the main drivers of genotoxicity through a multivariate analysis in order to establish a first partial genotoxicological profile of the Qatar Marine Zone. The 3 selected sampling sites, with expected different levels and sources of pollution were: South of Al Khor, Al Wakra harbor and South of Doha harbor. Two sampling campaigns were performed, one in summer and one in winter, to evaluate the role of the abiotic parameters, among others, on the bioavailability of the studied contaminants. The native pearl oyster Pinctada radiata was selected as model and surrogate species due to, its wide distribution along the Qatari coast, filter feeder and sessile mode of life and to its ability as a bivalve to bioaccumulate pollutants. Chemical analyses of the main trace metals and hydrocarbons were performed in water, sediment and P. radiata samples. The evaluation of the aneuploidy levels in P. radiata was estimated in 25-30 animals from each sampling site and season, by counting the total number of aneuploid metaphases over 30 metaphases counted per individual. The evaluation of the aneuploidy level on Pinctada radiata from the three sampling sites revealed an occurrence of significantly higher levels in Al-Wakra harbor (17% in summer and 20% in winter) and South of Doha harbor (19% in summer and 17% in winter), when compared to Al Khor (5% in summer cand 7% in winter). No statistically significant differences were observed between seasons in each location. In order to investigate the discrepancy between sampling sites and seasons with respect to all estimated descriptors and to evaluate the relationship between all the studied parameters, a principal component analysis (PCA) was performed. Aneuploidy levels were highly correlated to mercury and PAHs levels in the bivalve tissue. Moreover, the higher aneuploidy levels registered at Al Wakra harbor (both seasons) and Doha harbor (summer) showed a high correlation with the contaminants levels in P. radiata tissues. South of Al Khor (in both sampling seasons) was highly positively correlated with Cadmium (Cd), although this contamination was not responsible for a significant increase of the aneuploidy levels. The studied genotoxic contaminants were found to be highly variable among considered locations and between sampling seasons. Indeed, the 6 observations (contaminants levels among three sampling sites at two sampling seasons) differ substantially, no site or sampling season grouping being observed, which suggests an important spatial and temporal variability of the bioaccumulation of pollutants into P. radiata tissues. The aneuploidy levels, however, were consistently different among sampled locations, but did not differ between the two sampling seasons, suggesting that aneuploidy is the consequence of a local chronic contamination, and not a direct response to the temporal variability of the contaminants in P. radiata tissues. The results of this study confirm the suitability of the cytogenetic endpoints to discriminate, categorize the studied sites as regards to their level of contamination, underlining the added value of the detection of the genotoxicity levels in the marine environment to environmental health assessment and mitigation research programs. Further studies should be developed, under the specific hydrological and toxicological conditions of the Qatar Marine Zone (QMZ), to better explain the underlining mechanisms of such genotoxicity in the local filter feeders. The establishment of a Genotoxicological profile of the QMZ would be a valuable contribution to a wider approach on environmental diagnosis or prognosis, contributing to the protection and sustainability of the QMZ natural habitats and resources.qscienc

Uncovering responses of zooplankton community to CO2 acidification in Qatar coastal waters

The combustion of fossil fuels is pushing atmospheric concentrations of carbon dioxide (CO2) to unprecedented levels. This rapid increase in atmospheric CO2 is causing global changes, with noticeable increases in temperature, sea level rise and changes to marine carbon chemistry (i.e., Ocean Acidification - OA). The today average pH of ocean surface waters has already declined by 0.1 units from pre-industrial levels. According to the IPCC representative concentration pathways (RCPs), further declines in pH are predicted until the end of the century, varying between 0.14 units and 0.43 units. OA is irreversible on short time frames and previous studies have shown the potential impacts of ocean acidification on the physiology, reproduction, immunology and behavior of marine organisms, with effects already documented in multiple species and several regions of the world, although not in the Arabian Gulf. Nevertheless, the strong environmental variability of the Arabian Gulf presents good opportunities to study the potential impacts of future global change on marine ecosystems and to investigate the underlying mechanisms governing their resistance and adaptation to future environmental extremes. In this research we are targeting the response of zooplanktonic assemblages to OA, since these are commonly used as bioindicators of environmental and climate driven impact on marine ecosystems. The approach is mainly experimental, using controlled CO2 perturbation experiments, done aboard the Qatar University research vessel “Janan”. We are specifically investigating the response of zooplankton communities to relevant scenarios of seawater acidification by CO2, in terms of assemblage composition and structure; respiration rates; and egg production rates. The first round of experiments was conducted during a 3 day cruise offshore from Doha (June 3–5, 2016); complemented with a second cruise and round of experiments (November 17–19, 2016). Results provide insightful information about zooplankton communities’ responses to high CO2 levels in seawater of the Arabian Gulf and contribute to a better understanding about the biogeochemistry of coastal marine areas in Qatar, and more broadly in the Arabian Gulf.This study is funded by QNRF through the project “Zooplankton community responses to CO2 acidification in Qatar coastal waters (UREP18-177-1-021)

Connaissances des Anomalies du Tube Neural, Attitudes et Pratiques de Prévention chez les Femmes vues en Consultation prénatale, Région de Niamey-Niger, 2017: Knowledge, Attitudes and Prevention Practices of Neural Tube Anomalies in Women attending Prenatal Consultation in the Niamey-Niger Region 2017

Introduction: Les anomalies congénitales sont des anomalies fonctionnelles, structurelles ou métaboliques se produisant en intra-utérin et identifiables avant ou après la naissance. Au Niger, le domaine des anomalies congénitales n'a pas été suffisamment exploré. Notre objectif était de décrire les connaissances des anomalies du tube neural (ATN), les attitudes et les pratiques de prévention chez les femmes vues en consultation prénatale (CPN). Méthodes: Nous avons mené une enquête transversale de Février â Mars 2017 chez les femmes enceintes vues en CPN1 dans les maternités de Niamey. L'échantillon, calculé avec Open Epi était de 421. Les femmes enceintes ont été interviewées sur leurs connaissances des ATN, leurs attitudes et pratiques de prévention devant ces anomalies. Les données ont été collectées avec un questionnaire à travers les 5 districts sanitaires de la region de Niamey. Le nombre de femmes à enquêter par district a été alloué en tenant compte de l'importance relative des femmes en age de procréer (FAP) selon le district. Dans chaque district, il a été choisi par commodité, l'hôpital de district (HD), 2 maternités urbaines et 2 maternités rurales. Le nombre de femme par maternité a été déterminé selon le même procédé que dans les districts. A la maternité, les participantes ont été choisi de manière aléatoire. Des analyses univariées, bivariées et multivariées ont été réalisées. Des ratios de prévalence (RP), OR de prévalence (POR) à 95% ont été calculés. Les variables avec p&lt;0,25 en analyse bivariée, ont été intégrées dans le modèle logistique multiple. Résultats: L'âge médian des enquêtées était de 25 ans. Il y avait 60,81% de scolarisées et 24,33% de primigestes. Environ 30,65% connaissaient les ATN ; 15,92% avaient de bonnes attitudes ; 41,81% avaient utilisées l'acide folique (AF). La tranche d'êge de 25-49ans a été un facteur indépendant de la connaissance des ATN (p=0,0008) ; pour les attitudes : il s'agit de l'âge (25-49ans) (p=0,03), la prise d'AF (p=0,0002) ; pour la pratique : le niveau d'instruction (p=0,01), l'information par les agents de santé (p&lt; 0,0001), la connaissance d'autres sources d'AF (p=0,04). Conclusion: Il y avait une insuffisance de connaissances, d'attitudes et de pratiques de prévention devant les ATN chez les femmes enceintes. L'éducation continue, une politique d'enrichissement en AF de certains aliments s'impose. Background: Congenital anomalies are functional, structural or metabolic abnormalities occurring in the uterus and identifiable before or after birth. In Niger, the field of congenital anomalies has not been sufficiently explored. Our objective was to describe the knowledge of neural tube defects (NTDs), attitudes and prevention practices in women seen in antenatal care (ANC). Methods: We conducted a cross-sectional survey from February to March 2017 among pregnant women seen in CPN1 in maternity hospitals in Niamey. The sample, calculated with Open Epi, was 421. Pregnant women were interviewed on their knowledge of NTDs, their attitudes and prevention practices in the face of these anomalies. The data were collected with a questionnaire across the 5 health districts of the Niamey region. The number of women to be surveyed by district was allocated taking into account the relative importance of women of reproductive age (FAP) by district. In each district, it was chosen by convenience, the district hospital (HD), 2 urban maternities and 2 rural maternities. The number of women per maternity unit was determined using the same procedure as in the districts. In the maternity ward, the participants were chosen at random. Univariate, bivariate and multivariate analyzes were performed. 95% prevalence (PR), OR prevalence (POR) ratios were calculated. Variables with p &lt;0.25 in bivariate analysis were included in the multiple logistic model. Results: The median age of the respondents was 25 years. There were 60.81% of school children and 24.33% of primigravidae. About 30.65% were familiar with ATNs; 15.92% had good attitudes; 41.81% had used folic acid (FA). The age group of 25-49 years was an independent factor of knowledge of NTDs (p = 0.0008); for attitudes: it is about age (25-49 years) (p = 0.03), AF intake (p = 0.0002); for practice: level of education (p = 0.01), information by health workers (p &lt;0.0001), knowledge of other sources of FA (p = 0.04). Conclusion: There was a lack of knowledge, attitudes and prevention practices towards NTDs among pregnant women. Education continues, a policy of fortifying certain foods with AF is required

New features of quantum discord uncovered by q-entropies

The notion of quantum discord introduced by Ollivier and Zurek [Phys. Rev. Lett 88, 017901 (2001)] (see also Henderson and Vedral [J. Phys. A 34, 6899 (2001)]) has attracted increasing attention, in recent years, as an entropic quantifier of non-classical features pertaining to the correlations exhibited by bipartite quantum systems. Here we generalize the notion so as to encompass power-law q-entropies (that reduce to the standard Shannon entropy in the limit $q \to 1$) and study the concomitant consequences. The ensuing, new discord-like measures we advance describe aspects of non-classicality that are different from those associated with the standard quantum discord. A particular manifestation of this difference concerns a feature related to order. Let $D_1$ stand for the standard, Shannon-based discord measure and $D_q$ for the $q \ne 1$ one. If two quantum states $A$, $B$ are such that $D_1(A) > D_1(B)$, this order-relation does not remain invariant under a change from $D_1$ to $D_q$.Comment: 11 pages, 8 figure