33 research outputs found
E-government adoption in Qatar: An investigation of the citizens' perspective
No full textElectronic government (e-government) initiatives are in their early stages in many developing countries and faced
with various issues pertaining to their implementation, adoption and diffusion. Like many other developing
countries, the e-government initiative in the state of Qatar has faced a number of challenges since its inception in
2000. Using a survey based study this paper describes citizens‟ behavioural intention and adoption in terms of
applying and utilising the Unified Theory of Acceptance and Use of technology (UTAUT) model to explore the
adoption and diffusion of e-government services in the state of Qatar. A regression analysis was conducted to
examine the influence of e-government adoption factors and the empirical data revealed that performance
expectancy, effort expectancy, and social influences determine citizens‟ behavioural intention towards e-government.
Moreover, facilitating conditions and behavioural intention were found to determine citizens‟ use of e-government
services in the state of Qatar. Implications for practice and research are discussed
CR1 Knops blood group alleles are not associated with severe malaria in the Gambia
No full textThe Knops blood group antigen erythrocyte polymorphisms have been associated with reduced falciparum malaria-based in vitro rosette formation (putative malaria virulence factor). Having previously identified single-nucleotide polymorphisms (SNPs) in the human complement receptor 1 (CR1/CD35) gene underlying the Knops antithetical antigens Sl1/Sl2 and McC(a)/McC(b), we have now performed genotype comparisons to test associations between these two molecular variants and severe malaria in West African children living in the Gambia. While SNPs associated with Sl:2 and McC(b+) were equally distributed among malaria-infected children with severe malaria and control children not infected with malaria parasites, high allele frequencies for Sl 2 (0.800, 1,365/1,706) and McC(b) (0.385, 658/1706) were observed. Further, when compared to the Sl 1/McC(a) allele observed in all populations, the African Sl 2/McC(b) allele appears to have evolved as a result of positive selection (modified Nei-Gojobori test Ka-Ks/s.e.=1.77, P-valu
Identification of Plasmodium falciparum var1CSA and var2CSA domains that bind IgM natural antibodies
No full textMalaria in pregnancy is responsible for maternal anaemia, low-birth-weight babies and infant deaths. Plasmodium falciparum infected erythrocytes are thought to cause placental pathology by adhering to host receptors such as chondroitin sulphate A (CSA). CSA binding infected erythrocytes also bind IgM natural antibodies from normal human serum, a process that may facilitate placental adhesion or promote immune evasion. The parasite ligands that mediate placental adhesion are thought to be members of the variant erythrocyte surface antigen family P. falciparum erythrocyte membrane protein 1 (PfEMP1), encoded by the var genes. Two var gene sub-families, var1CSA and var2CSA, have been identified as parasite CSA binding ligands and are leading candidates for a vaccine to prevent pregnancy-associated malaria. We investigated whether these two var gene subfamilies implicated in CSA binding are also the molecules responsible for IgM natural antibody binding. By heterologous expression of domains in COS-7 cells, we found that both var1CSA and var2CSA PfEMP1 variants bound IgM, and in both cases the binding region was a DBL epsilon domain occurring proximal to the membrane. None of the domains from a control non-IgM-binding parasite (R29) bound IgM when expressed in COS-7 cells. These results show that PfEMP1 is a parasite ligand for non-immune IgM and are the first demonstration of a specific adhesive function for PfEMP1 epsilon type domains
Plasmodium falciparum:Rosettes do not protect merozoites from invasion-inhibitory antibodies
No full textRosetting is a parasite adhesion phenotype associated with severe malaria in African children. Why parasites form rosettes is unknown, although enhanced invasion or immune evasion have been suggested as possible functions. Previous work showed that rosetting does not enhance parasite invasion under standard in vitro conditions. We hypothesised that rosetting might promote invasion in the presence of host invasion-inhibitory antibodies, by allowing merozoites direct entry into the erythrocytes in the rosette and so minimising exposure to plasma antibodies. We therefore investigated whether rosetting influences invasion in the presence of invasion-inhibitory antibodies to MSP-1. We found no difference in invasion rates between isogenic rosetting and non-rosetting lines from two parasite strains, R29 and TM284, in the presence of MSP-1 antibodies (P = 0.62 and P = 0.63, Student's t test, TM284 and R29, respectively). These results do not support the hypothesis that rosettes protect merozoites from inhibitory antibodies during invasion. The biological function of rosetting remains unknown
КАК СУННИТУ ОТНОСИТЬСЯ К РАФИЗИТАМ: ОБ ОДНОМ ТРАКТАТЕ ИЗ СОБРАНИЯ ВОСТОЧНОГО ОТДЕЛА НБ ИМ. М. ГОРЬКОГО СПБГУ
No full textAbstract. This paper deals with the materials of a medieval treatise Muqaddima dar aswala wa ajwaba dar radd-i rafada li bad-i muhaqqiqin. Supposedly, the author of this work was a famous Muslim scholar and theologian ‘Ali b. Sultan Muhammad al-Harawi al-Hanafi al-Qari. This essay, written in the form of questions and answers, describes, according to its author’s position, the proper relation of faithful Muslim (Sunni of Shafi i) to the followers of blameworthy innovations (mubaddi) and ‘apostates’ (rafada, Shia); noteworthily, the author does not distinguish between the representatives of these two groups. This work is a striking example of ideological campaigns led in Iran and Central Asia over Shia-Sunni contradictions. Аннотация. Статья посвящена материалам средневекового трак тата Мукаддима дар асвала ва аджваба дар радд-и рафаза ли бад-и мухаккикин, автором которого пред- положительно является крупный мусульманский ученый-богослов ‘Али б. Султан Мухаммад ал-Хара- ви ал-Ханафи ал-Кари‘. Написанное в вопросах и ответах сочинение посвящено должному, с точки зрения автора, отношению верующего мусульманина (суннита-шафи‘ита) к сторонникам порицаемых ново- введений (мубадди‘) и «отступникам» (рафаза, ши ‘а), причем между последними не делается никаких различий. Сочинение можно считать одним из ярких проявлений идеологических кампаний, которые велись в Иране и Центральной Азии в контексте шиито-суннитских противоречий.
One-sided composite cavity on an optical nanofiber for cavity QED
No full textWe demonstrate a one-sided cavity on an optical nanofiber (ONF) using a composite method. The one-sided composite cavity is created by mounting an asymmetric defect mode grating on an ONF. We design the one-sided composite cavity on an ONF to enhance channeling efficiency into one side of ONF while operating from under- to critical- and over-coupling regimes using numerical simulations. Experimentally, we demonstrate coupling characteristics of the one-sided composite cavity, showing good correspondence with simulation results
Experimental realization of universal quantum gates and six-qubit state using photonic quantum walk
No full textControlled quantum walk forms the basis for various quantum algorithm and
quantum simulation schemes. Though theoretical proposals are also available to
realize universal quantum computation using quantum walks, no experimental
demonstration of universal set of gates has been reported. Here we report the
experimental realize of universal set of quantum gates using photonic quantum
walk. Taking cue from the discrete-time quantum walk formalism, we encode
multiple qubits using polarization and paths degree of freedom for photon and
demonstrate realization of universal set of gates with 100\% success
probability and high fidelity, as characterised by quantum state tomography.
For a 3-qubit system we encode first qubit with and polarization of
photon and path information for the second and third qubit, closely resembling
a Mach-Zehnder interference setup. To generate a 6-qubit system and demonstrate
6-qubit GHZ state, entangled photon pairs are used as source to two 3-qubit
systems. We also provide insights into the mapping of quantum circuits to
quantum walk operations on photons and way to resourcefully scale. This work
marks a significant progress towards using photonic quantum walk for quantum
computing. It also provides a framework for photonic quantum computing using
lesser number of photons in combination with path degree of freedom to increase
the success rate of multi-qubit gate operations.Comment: 13 pages, 8 figures. Tomography figures for all gate operations are
available upon reques
Bell-inequality in path-entangled single photon and purity of single photon state
No full textDifferent degrees of freedom of single photons have been entangled and are
used as a resource for various quantum technology applications. We present a
simple scheme to perform Bell's test and show the violation of CHSH inequality
in a path-entangled single photon state using interferometric and its
equivalent non-interferometric approach in beam splitter setting. We
demonstrate this experimentally by generating and controlling path-entangled
state using both, heralded and un-heralded single photons from spontaneous
parametric down-conversion. The experimental results we present show the
transition to violation of CHSH inequality when the purity of single photons
state visibility increase above 70\% , . Our procedure using
single beam splitter and two detector module for un-heralded single photon
source allows a simple way to test for purity of any single photon source and
to study quantum correlations on systems driven by dynamics where single
particle entanglement with position space is prominent.Comment: 11 pages, 11 figures revised version with extended theoretical
description and additional experimental resul
Integration of silicon-vacancy centers in nanodiamonds with an optical nanofiber
No full textWe experimentally demonstrate the integration of silicon-vacancy centers in
nanodiamonds (SiV-NDs) with an optical nanofiber (ONF). We grow SiV-NDs on seed
NDs dispersed on a quartz substrate using a microwave plasma-assisted chemical
vapor deposition method. First, we search and characterize SiV-NDs on a quartz
substrate using an inverted confocal microscope and an atomic force microscope
(AFM). Subsequently, we pick up SiV-NDs from the quartz substrate and deposit
them on the surface of a free-standing ONF using the AFM tip. The fluorescence
emission spectrum, photon count rate, and intensity correlations for SiV-NDs
are systematically measured.Comment: 6 pages, 4 figure
