Measuring for Knowledge: A Data-Driven Research Approach for eGovernment

As ICT provide a lot of possibilities, high expectancies exist towards the electronic public service provision. All governments are increasingly establishing their e-strategies. However, eGovernment still faces many challenges as it continues to develop. The current status of electronic services delivery opens up a lot of questions, both for practitioners and researchers. Therefore, further progress of eGovernment needs a profound knowledge base. eGovernment policy has focused several years on bringing online public services and on benchmarking their availability and sophistication. Simultaneously, eGovernment measurement and monitoring activities are often based on the so-called supply-side benchmarking. Although this is important knowledge, it is under criticism because it lacks a user-centric viewpoint of eGovernment development. This article presents and discusses a bottom-up and data-driven approach about how research can help to manage (user-centric) eGovernment strategies. Based on statistical testing (techniques of structural equation modeling, SEM) of large-scale sample data from the Belgian government, the authors have investigated which relations do exist between contextual variables and the availability and/or satisfaction of electronic public services. By doing this, this manuscript presents an illustration of a data-driven approach in eGovernment monitoring and it explains how this can support and enrich the management and evaluation of eGovernment policy

Gigahertz repetition rate thermionic electron gun concept

We present a novel concept for the generation of gigahertz repetition rate high brightness electron bunches. A custom design 100 kV thermionic gun provides a continuous electron beam, with the current determined by the filament size and temperature. A 1 GHz rectangular RF cavity deflects the beam across a knife-edge, creating a pulsed beam. Adding a higher harmonic mode to this cavity results in a flattened magnetic field profile which increases the duty cycle to 30%. Finally, a compression cavity induces a negative longitudinal velocity-time chirp in a bunch, initiating ballistic compression. Adding a higher harmonic mode to this cavity increases the linearity of this chirp and thus decreases the final bunch length. Charged particle simulations show that with a 0.15 mm radius LaB6 filament held at 1760 K, this method can create 279 fs, 3.0 pC electron bunches with a radial rms core emittance of 0.089 mm mrad at a repetition rate of 1 GHz.Comment: 12 pages, 12 figure

Heterogeneity among Mycobacterium ulcerans isolates from Africa

Mycobacterium ulcerans causes Buruli ulcer, an ulcerative skin disease in tropical and subtropical areas. Despite restricted genetic diversity, mycobacterial interspersed repetitive unit-variable-number tandem repeat analysis on M. ulcerans revealed 3 genotypes from different African countries. It is the first time this typing method succeeded directly on patient samples

Theory and particle tracking simulations of a resonant radiofrequency deflection cavity in TM110_{110} mode for ultrafast electron microscopy

We present a theoretical description of resonant radiofrequency (RF) deflecting cavities in TM$_{110}$ mode as dynamic optical elements for ultrafast electron microscopy. We first derive the optical transfer matrix of an ideal pillbox cavity and use a Courant-Snyder formalism to calculate the 6D phase space propagation of a Gaussian electron distribution through the cavity. We derive closed, analytic expressions for the increase in transverse emittance and energy spread of the electron distribution. We demonstrate that for the special case of a beam focused in the center of the cavity, the low emittance and low energy spread of a high quality beam can be maintained, which allows high-repetition rate, ultrafast electron microscopy with 100 fs temporal resolution combined with the atomic resolution of a high-end TEM. This is confirmed by charged particle tracking simulations using a realistic cavity geometry, including fringe fields at the cavity entrance and exit apertures

Application of relativistic scattering theory of x rays to diffraction anomalous fine structure in Cu

We apply our recent first-principles formalism of magnetic scattering of circularly polarized x rays to a single Cu crystal. We demonstrate the ability of our formalism to interpret the crystalline environment related near-edge fine structure features in the resonant x-ray scattering spectra at the Cu K absorption edge. We find good agreement between the computed and measured diffraction anomalous fine structure features of the x-ray scattering spectra

Genetic Diversity of PCR-Positive, Culture-Negative and Culture-Positive Mycobacterium ulcerans Isolated from Buruli Ulcer Patients in Ghana.

Culture of Mycobacterium ulcerans from Buruli ulcer patients has very low sensitivity. Thus confirmation of M. ulcerans infection is primarily based on PCR directed against IS2404. In this study we compare the genotypes obtained by variable number of tandem repeat analysis of DNA from IS2404-PCR positive cultures with that obtained from IS2404 positive, culture-negative tissue. A significantly greater genetic heterogeneity was found among culture-negative samples compared with that found in cultured strains but a single genotype is over-represented in both sample sets. This study provides evidence that both the focal location of bacteria in a lesion as well as differences in the ability to culture a particular genotype may underlie the low sensitivity of culture. Though preliminary, data from this work also suggests that mycobacteria previously associated with fish disease (M. pseudoshottsii) may be pathogenic for humans

mazF, a novel counter-selectable marker for unmarked chromosomal manipulation in Bacillus subtilis

Here, we present a novel method for the directed genetic manipulation of the Bacillus subtilis chromosome free of any selection marker. Our new approach employed the Escherichia coli toxin gene mazF as a counter-selectable marker. The mazF gene was placed under the control of an isopropyl-β-d-thiogalactopyranoside (IPTG)-inducible expression system and associated with a spectomycin-resistance gene to form the MazF cassette, which was flanked by two directly-repeated (DR) sequences. A double-crossover event between the linearized delivery vector and the chromosome integrated the MazF cassette into a target locus and yielded an IPTG-sensitive strain with spectomycin-resistance, in which the wild-type chromosome copy had been replaced by the modified copy at the targeted locus. Another single-crossover event between the two DR sequences led to the excision of the MazF cassette and generated a strain with IPTG resistance, thereby realizing the desired alteration to the chromosome without introducing any unwanted selection markers. We used this method repeatedly and successfully to inactivate a specific gene, to introduce a gene of interest and to realize the in-frame deletion of a target gene in the same strain. As there is no prerequisite strain for this method, it will be a powerful and universal tool

Genomic Diversity and Evolution of Mycobacterium ulcerans Revealed by Next-Generation Sequencing

Mycobacterium ulcerans is the causative agent of Buruli ulcer, the third most common mycobacterial disease after tuberculosis and leprosy. It is an emerging infectious disease that afflicts mainly children and youths in West Africa. Little is known about the evolution and transmission mode of M. ulcerans, partially due to the lack of known genetic polymorphisms among isolates, limiting the application of genetic epidemiology. To systematically profile single nucleotide polymorphisms (SNPs), we sequenced the genomes of three M. ulcerans strains using 454 and Solexa technologies. Comparison with the reference genome of the Ghanaian classical lineage isolate Agy99 revealed 26,564 SNPs in a Japanese strain representing the ancestral lineage. Only 173 SNPs were found when comparing Agy99 with two other Ghanaian isolates, which belong to the two other types previously distinguished in Ghana by variable number tandem repeat typing. We further analyzed a collection of Ghanaian strains using the SNPs discovered. With 68 SNP loci, we were able to differentiate 54 strains into 13 distinct SNP haplotypes. The average SNP nucleotide diversity was low (average 0.06–0.09 across 68 SNP loci), and 96% of the SNP locus pairs were in complete linkage disequilibrium. We estimated that the divergence of the M. ulcerans Ghanaian clade from the Japanese strain occurred 394 to 529 thousand years ago. The Ghanaian subtypes diverged about 1000 to 3000 years ago, or even much more recently, because we found evidence that they evolved significantly faster than average. Our results offer significant insight into the evolution of M. ulcerans and provide a comprehensive report on genetic diversity within a highly clonal M. ulcerans population from a Buruli ulcer endemic region, which can facilitate further epidemiological studies of this pathogen through the development of high-resolution tools