248 research outputs found

    Generalized Supersymmetric Perturbation Theory

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    Using the basic ingredient of supersymmetry, we develop a simple alternative approach to perturbation theory in one-dimensional non-relativistic quantum mechanics. The formulae for the energy shifts and wave functions do not involve tedious calculations which appear in the available perturbation theories. The model applicable in the same form to both the ground state and excited bound states, unlike the recently introduced supersymmetric perturbation technique which, together with other approaches based on logarithmic perturbation theory, are involved within the more general framework of the present formalism.Comment: 13 pages article in LaTEX (uses standard article.sty). No Figures. Sent to Ann. Physics (2004

    Improving road safety knowledge in Africa through crowdsourcing. The African Road Safety Observatory

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    Africa is the worst performing continent in road safety: the fatality rate, 26.6 per 100.000 inhabitants, is almost three times that of Europe's and fatalities per capita are projected to double from 2015 to 2030 (WHO, 2015). This is mainly due to the fact that Emerging Economies are experiencing increases in traffic, for which their traffic systems are not sufficiently prepared. On one hand, there is a significant demand for data and knowledge to be used for road safety-related decision making. On the other hand, there is a substantial lack of a reliable and detailed knowledge on road casualties in terms of the number of road accidents and fatalities occurring and, on the factors, leading to road accidents or affecting their consequences. When official data are poor or missing these could be integrated with other sources. The objective of this paper is to describe the African Road Safety Observatory (African RSO), a participative web portal developed in the field of the "SaferAfrica-Innovating dialogue and problems appraisal for a safer Africa" project, funded by the European Union's Horizon 2020 program. The African RSO combines traditional functions of analyzing and sharing road safety performance data and provide knowledge and information, with the more innovative ones: a Dialogue Platform and the crowdsourcing tool. The Dialogue Platform is dedicated to experts and stakeholders and aims at encouraging and facilitating a constructive engagement and dialogue on road safety in Africa, producing knowledge to inspire road safety funding, policies and interventions in Africa and providing recommendations to update the African Road Safety Action Plan and the African Road Safety Charter. The crowdsourcing tool allows African citizens to report and highlight road safety needs, to share opinions as well as to discuss solutions in their own Countries

    Comparison of techniques for computing shell-model effective operators

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    Different techniques for calculating effective operators within the framework of the shell model using the same effective interaction and the same excitation spaces are presented. Starting with the large-basis no-core approach, we compare the time-honored perturbation-expansion approach and a model-space truncation approach. Results for the electric quadrupole and magnetic dipole operators are presented for 6^6Li. The convergence trends and dependence of the effective operators on differing excitation spaces and Pauli Q-operators is studied. In addition, the dependence of the electric-quadrupole effective charge on the harmonic-oscillator frequency and the mass number, for A=5,6, is investigated in the model-space truncation approach.Comment: 18 pages. REVTEX. 4 PostScript figure

    Dialysis Initiation in Patients With Chronic Coronary Disease and Advanced Chronic Kidney Disease in ISCHEMIA-CKD

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    Background In participants with concomitant chronic coronary disease and advanced chronic kidney disease (CKD), the effect of treatment strategies on the timing of dialysis initiation is not well characterized. Methods and Results In ISCHEMIA-CKD (International Study of Comparative Health Effectiveness With Medical and Invasive Approaches-Chronic Kidney Disease), 777 participants with advanced CKD and moderate or severe ischemia were randomized to either an initial invasive or conservative management strategy. Herein, we compare the proportion of randomized participants with non-dialysis-requiring CKD at baseline (n=362) who initiated dialysis and compare the time to dialysis initiation between invasive versus conservative management arms. Using multivariable Cox regression analysis, we also sought to identify the effect of invasive versus conservative chronic coronary disease management strategies on dialysis initiation. At a median follow-up of 23 months (25th-75th interquartile range, 14-32 months), dialysis was initiated in 18.9% of participants (36/190) in the invasive strategy and 16.9% of participants (29/172) in the conservative strategy (P=0.22). The median time to dialysis initiation was 6.0 months (interquartile range, 3.0-16.0 months) in the invasive group and 18.2 months (interquartile range, 12.2-25.0 months) in the conservative group (P=0.004), with no difference in procedural acute kidney injury rates between the groups (7.8% versus 5.4%; P=0.26). Baseline clinical factors associated with earlier dialysis initiation were lower baseline estimated glomerular filtration rate (hazard ratio [HR] associated with 5-unit decrease, 2.08 [95% CI, 1.72-2.56]; P<0.001), diabetes (HR, 2.30 [95% CI, 1.28-4.13]; P=0.005), hypertension (HR, 7.97 [95% CI, 1.09-58.21]; P=0.041), and Hispanic ethnicity (HR, 2.34 [95% CI, 1.22-4.47]; P=0.010). Conclusions In participants with non-dialysis-requiring CKD in ISCHEMIA-CKD, randomization to an invasive chronic coronary disease management strategy (relative to a conservative chronic coronary disease management strategy) is associated with an accelerated time to initiation of maintenance dialysis for kidney failure.U01 HL117904/HL/NHLBI NIH HHS/United Statesinfo:eu-repo/semantics/publishedVersio

    Metagenomics reveals our incomplete knowledge of global diversity

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    Financial support was provided by projects BFU2006-06003 from the Spanish Ministry of Education and Science (MEC) and GV/2007/050 from the Generalitat Valenciana, Spain. J.T. is a recipient of a contract in the FIS Program from ISCIII, Spanish Ministry of Health.Pignatelli, M.; Aparicio Pla, G.; Blanquer Espert, I.; Hernández García, V.; Moya, A.; Tamames, J. (2008). Metagenomics reveals our incomplete knowledge of global diversity. Bioinformatics. 24(18):2124-2125. https://doi.org/10.1093/bioinformatics/btn355S212421252418Koski, L. B., & Golding, G. B. (2001). The Closest BLAST Hit Is Often Not the Nearest Neighbor. Journal of Molecular Evolution, 52(6), 540-542. doi:10.1007/s002390010184Krause, L., Diaz, N. N., Goesmann, A., Kelley, S., Nattkemper, T. W., Rohwer, F., … Stoye, J. (2008). Phylogenetic classification of short environmental DNA fragments. Nucleic Acids Research, 36(7), 2230-2239. doi:10.1093/nar/gkn038Mavromatis, K., Ivanova, N., Barry, K., Shapiro, H., Goltsman, E., McHardy, A. C., … Kyrpides, N. C. (2007). Use of simulated data sets to evaluate the fidelity of metagenomic processing methods. Nature Methods, 4(6), 495-500. doi:10.1038/nmeth1043Tamames, J., & Moya, A. (2008). Estimating the extent of horizontal gene transfer in metagenomic sequences. BMC Genomics, 9(1), 136. doi:10.1186/1471-2164-9-136Tringe, S. G. (2005). Comparative Metagenomics of Microbial Communities. Science, 308(5721), 554-557. doi:10.1126/science.1107851Tringe, S. G., Zhang, T., Liu, X., Yu, Y., Lee, W. H., Yap, J., … Ruan, Y. (2008). The Airborne Metagenome in an Indoor Urban Environment. PLoS ONE, 3(4), e1862. doi:10.1371/journal.pone.0001862COLE, F. N. (1900). AMERICAN MATHEMATICAL SOCIETY. Science, 11(263), 66-67. doi:10.1126/science.11.263.6

    The genome and transcriptome of Trichormus sp NMC-1: insights into adaptation to extreme environments on the Qinghai-Tibet Plateau

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    The Qinghai-Tibet Plateau (QTP) has the highest biodiversity for an extreme environment worldwide, and provides an ideal natural laboratory to study adaptive evolution. In this study, we generated a draft genome sequence of cyanobacteria Trichormus sp. NMC-1 in the QTP and performed whole transcriptome sequencing under low temperature to investigate the genetic mechanism by which T. sp. NMC-1 adapted to the specific environment. Its genome sequence was 5.9 Mb with a G+C content of 39.2% and encompassed a total of 5362 CDS. A phylogenomic tree indicated that this strain belongs to the Trichormus and Anabaena cluster. Genome comparison between T. sp. NMC-1 and six relatives showed that functionally unknown genes occupied a much higher proportion (28.12%) of the T. sp. NMC-1 genome. In addition, functions of specific, significant positively selected, expanded orthogroups, and differentially expressed genes involved in signal transduction, cell wall/membrane biogenesis, secondary metabolite biosynthesis, and energy production and conversion were analyzed to elucidate specific adaptation traits. Further analyses showed that the CheY-like genes, extracellular polysaccharide and mycosporine-like amino acids might play major roles in adaptation to harsh environments. Our findings indicate that sophisticated genetic mechanisms are involved in cyanobacterial adaptation to the extreme environment of the QTP
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