244 research outputs found
Single Transfer-Excitation Resonance Observed Via the Two-Photon Decay in He-like GeÂłâ°âș
We measured the 2E1 decay of the 1s2s 1S0 â1s2 1S0 transition in He-like germanium for 12- to 19-MeV/u Ge31+ +H2 collisions. The resonant population of the 2s2p 1P1 state by transfer excitation was isolated due to its cascading to the 1s2s 1S0 state. The experimental cross sections compare well with calculations using dielectronic recombination rates. The method gives the unique possibility to populate selectively the 1S0 state in heavy He-like ions
Heteroatom and side chain effects on the optical and photophysical properties: ultrafast and nonlinear spectroscopy of new Naphtho[1,2-b:5,6-b ']difuran donor polymers
The photophysical and electronic properties of four novel conjugated donor polymers were investigated to understand the influence of heteroatoms (based on the first two member chalcogens) in the polymer backbone. The side chains were varied as well to evaluate the effect of polymer solubility on the photophysical properties. The donorâacceptor polymer structure is based on naptho[1,2-b:5,6-bâČ]difuran as the donor moiety, and either 3,6-di(furan-2-yl)-1,4-diketopyrrolo[3,4-c]pyrrole or 3,6-di(thiophen-2-yl)-1,4-diketopyrrolo[3,4-c]pyrrole as the acceptor moiety. Steady-state absorption studies showed that the polymers with the furan moiety in the backbone displayed a favorable tendency of capturing more solar photons when used in a photovoltaic device. This is observed experimentally by the higher extinction coefficient in the visible and near-infrared regions of these polymers relative to that of their thiophene counterparts. The excitonic lifetimes were monitored using ultrafast dynamics, and the results obtained show that the type of heteroatom Ï-linker used in the backbone affects the decay dynamics. Furthermore, the side chain also plays a role in determining the fluorescence decay time. Quantum chemical simulations were performed to describe the absorption energies and transition characters. Two-photon absorption cross sections (TPA-ÎŽ) were analyzed with the simulations, illustrating the planarity of the backbone in relation to its torsional angles. Because of the planarity in the molecular backbone, the polymer with the furan Ï-linker showed a higher TPA-ÎŽ relative to that of its thiophene counterpart. This suggests that the furan compound will display higher charge transfer (CT) tendencies in comparison to those of their thiophene analogues. The pumpâprobe transient absorption technique was employed to probe the nonemissive states (including the CT state) of the polymers, and unique activities were captured at 500 and 750 nm for all of the studied compounds. Target and global analyses were performed to understand the dynamics of each peak and deduce the number of components responsible for the transient behavior observed respectively. The results obtained suggest that the furan Ï-linker component of a donor and acceptor moiety in a conjugated polymer might be a more suitable candidate compared with its more popular chalcogenic counterpart, thiophene, for use as donor materials in bulk heterojunction photovoltaic devices.Support for this investigation is provided by the National Science Foundation (DMR-1709005) Polymers (TGIII) and (DMR 1410088/1640297) Polymers (MJE). (DMR-1709005 - National Science Foundation; DMR 1410088/1640297 - National Science Foundation)Accepted manuscrip
Isotope Shift in the Dielectronic Recombination of Three-electron \u3csup\u3eA\u3c/sup\u3eNdâ”â·âș
Isotope shifts in dielectronic recombination spectra were studied for Li-like ANd57+ ions with A = 142 and A = 150. From the displacement of resonance positions energy shifts ÎŽE142 150(2s-2p1/2) = 40.2(3)(6) meV [(stat)(sys)] and ÎŽE142 150(2s - 2p3/2) = 42.3(12)(20)meV of 2s - 2pj transitions were deduced. An evaluation of these values within a full QED treatment yields a change in the mean-square charge radius of 142 150ÎŽâš r2â© = -1.36(1)(3) fm2. The approach is conceptually new and combines the advantage of a simple atomic structure with high sensitivity to nuclear size
LSST: from Science Drivers to Reference Design and Anticipated Data Products
(Abridged) We describe here the most ambitious survey currently planned in
the optical, the Large Synoptic Survey Telescope (LSST). A vast array of
science will be enabled by a single wide-deep-fast sky survey, and LSST will
have unique survey capability in the faint time domain. The LSST design is
driven by four main science themes: probing dark energy and dark matter, taking
an inventory of the Solar System, exploring the transient optical sky, and
mapping the Milky Way. LSST will be a wide-field ground-based system sited at
Cerro Pach\'{o}n in northern Chile. The telescope will have an 8.4 m (6.5 m
effective) primary mirror, a 9.6 deg field of view, and a 3.2 Gigapixel
camera. The standard observing sequence will consist of pairs of 15-second
exposures in a given field, with two such visits in each pointing in a given
night. With these repeats, the LSST system is capable of imaging about 10,000
square degrees of sky in a single filter in three nights. The typical 5
point-source depth in a single visit in will be (AB). The
project is in the construction phase and will begin regular survey operations
by 2022. The survey area will be contained within 30,000 deg with
, and will be imaged multiple times in six bands, ,
covering the wavelength range 320--1050 nm. About 90\% of the observing time
will be devoted to a deep-wide-fast survey mode which will uniformly observe a
18,000 deg region about 800 times (summed over all six bands) during the
anticipated 10 years of operations, and yield a coadded map to . The
remaining 10\% of the observing time will be allocated to projects such as a
Very Deep and Fast time domain survey. The goal is to make LSST data products,
including a relational database of about 32 trillion observations of 40 billion
objects, available to the public and scientists around the world.Comment: 57 pages, 32 color figures, version with high-resolution figures
available from https://www.lsst.org/overvie
Antibody responses to <i>P. falciparum</i> blood stage antigens and incidence of clinical malaria in children living in endemic area in Burkina Faso
Abstract Background High parasite-specific antibody levels are generally associated with low susceptibility to Plasmodium falciparum malaria. This has been supported by several studies in which clinical malaria cases of P. falciparum malaria were reported to be associated with low antibody avidities. This study was conducted to evaluate the role of age, malaria transmission intensity and incidence of clinical malaria in the induction of protective humoral immune response against P. falciparum malaria in children living in Burkina Faso. Methods We combined levels of IgG and IgG subclasses responses to P. falciparum antigens: Merozoite Surface Protein 3 (MSP3), Merozoite Surface Protein 2a (MSP2a), Merozoite Surface Protein 2b (MSP2b), Glutamate Rich Protein R0 (GLURP R0) and Glutamate Rich Protein R2 (GLURP R2) in plasma samples from 325 children under five (05) years with age, malaria transmission season and malaria incidence. Results We notice higher prevalence of P. falciparum infection in low transmission season compared to high malaria transmission season. While, parasite density was lower in low transmission than high transmission season. IgG against all antigens investigated increased with age. High levels of IgG and IgG subclasses to all tested antigens except for GLURP R2 were associated with the intensity of malaria transmission. IgG to MSP3, MSP2b, GLURP R2 and GLURP R0 were associated with low incidence of malaria. All IgG subclasses were associated with low incidence of P. falciparum malaria, but these associations were stronger for cytophilic IgGs. Conclusions On the basis of the data presented in this study, we conclude that the induction of humoral immune response to tested malaria antigens is related to age, transmission season level and incidence of clinical malaria
Comparative and Joint Analysis of Two Metagenomic Datasets from a Biogas Fermenter Obtained by 454-Pyrosequencing
Biogas production from renewable resources is attracting increased attention as an alternative energy source due to the limited availability of traditional fossil fuels. Many countries are promoting the use of alternative energy sources for sustainable energy production. In this study, a metagenome from a production-scale biogas fermenter was analysed employing Roche's GS FLX Titanium technology and compared to a previous dataset obtained from the same community DNA sample that was sequenced on the GS FLX platform. Taxonomic profiling based on 16S rRNA-specific sequences and an Environmental Gene Tag (EGT) analysis employing CARMA demonstrated that both approaches benefit from the longer read lengths obtained on the Titanium platform. Results confirmed Clostridia as the most prevalent taxonomic class, whereas species of the order Methanomicrobiales are dominant among methanogenic Archaea. However, the analyses also identified additional taxa that were missed by the previous study, including members of the genera Streptococcus, Acetivibrio, Garciella, Tissierella, and Gelria, which might also play a role in the fermentation process leading to the formation of methane. Taking advantage of the CARMA feature to correlate taxonomic information of sequences with their assigned functions, it appeared that Firmicutes, followed by Bacteroidetes and Proteobacteria, dominate within the functional context of polysaccharide degradation whereas Methanomicrobiales represent the most abundant taxonomic group responsible for methane production. Clostridia is the most important class involved in the reductive CoA pathway (Wood-Ljungdahl pathway) that is characteristic for acetogenesis. Based on binning of 16S rRNA-specific sequences allocated to the dominant genus Methanoculleus, it could be shown that this genus is represented by several different species. Phylogenetic analysis of these sequences placed them in close proximity to the hydrogenotrophic methanogen Methanoculleus bourgensis. While rarefaction analyses still indicate incomplete coverage, examination of the GS FLX Titanium dataset resulted in the identification of additional genera and functional elements, providing a far more complete coverage of the community involved in anaerobic fermentative pathways leading to methane formation
Transition, Integration and Convergence. The Case of Romania
This volume comprises several studies and papers published in the last decades. They have been selected and ranged so that to provide a minimum of coherence concerning the phases which Romania has crossed in her way to the advanced socio-economic system of European type: transition to the market economy, accession to the EU, the economic convergence in the three fundamental domains: institutions, real economy, and nominal economy. The readers may find in this volume a description of debates, difficulties and solutions adopted for building-up the market economy by a state being in a profound transformation from weak transition institutions towards hard democratic institutions. Because the transition to the market economy and the association of Romania with the EU and then the integration presenting strategic political decisions, I have included in this work two studies devoted to the political forces state and political parties that elaborated and applied these strategic decisions underlining their structure, role and function and their transformation. Integration into the EU of a country like Romania, which emerged from a different system comparing with the West-European one, has proved to be difficult and lasting many years because of the structural transformations. In five chapters I am referring to the essential characteristics of the integration process, such as: market liberalization, competitiveness of the local (national) firms on the national and EU markets, institutional reforms so that the institutions of candidate countries have to become compatible with those of the EU and finally the perspective assessment to find out the real and nominal convergence. Putting into practice the EU competitivity and cohesion principles, Romania has good prospects to close, in a reasonable time, the economic gap and to be admitted into the Euro Zone. Although the real convergence of Romania with the EU requires higher growth rates for the former, a new approach is compulsory to take into consideration the environment quality, the natural resources and the equity between the present and the future generations as natural resource consumers. Just these problems have determined me to include in this volume the last two chapters which, on the one hand, try to prove the necessity of the economy growth harmonization with the environment evolution as well as the saving of the energy resources, and, on the other hand, to point out the main ways to be followed and instruments to be used
Stroke genetics informs drug discovery and risk prediction across ancestries
Previous genome-wide association studies (GWASs) of stroke â the second leading cause of death worldwide â were conducted predominantly in populations of European ancestry1,2. Here, in cross-ancestry GWAS meta-analyses of 110,182 patients who have had a stroke (five ancestries, 33% non-European) and 1,503,898 control individuals, we identify association signals for stroke and its subtypes at 89 (61 new) independent loci: 60 in primary inverse-variance-weighted analyses and 29 in secondary meta-regression and multitrait analyses. On the basis of internal cross-ancestry validation and an independent follow-up in 89,084 additional cases of stroke (30% non-European) and 1,013,843 control individuals, 87% of the primary stroke risk loci and 60% of the secondary stroke risk loci were replicated (Pâ<â0.05). Effect sizes were highly correlated across ancestries. Cross-ancestry fine-mapping, in silico mutagenesis analysis3, and transcriptome-wide and proteome-wide association analyses revealed putative causal genes (such as SH3PXD2A and FURIN) and variants (such as at GRK5 and NOS3). Using a three-pronged approach4, we provide genetic evidence for putative drug effects, highlighting F11, KLKB1, PROC, GP1BA, LAMC2 and VCAM1 as possible targets, with drugs already under investigation for stroke for F11 and PROC. A polygenic score integrating cross-ancestry and ancestry-specific stroke GWASs with vascular-risk factor GWASs (integrative polygenic scores) strongly predicted ischaemic stroke in populations of European, East Asian and African ancestry5. Stroke genetic risk scores were predictive of ischaemic stroke independent of clinical risk factors in 52,600 clinical-trial participants with cardiometabolic disease. Our results provide insights to inform biology, reveal potential drug targets and derive genetic risk prediction tools across ancestries
26th Annual Computational Neuroscience Meeting (CNS*2017): Part 3 - Meeting Abstracts - Antwerp, Belgium. 15â20 July 2017
This work was produced as part of the activities of FAPESP Research,\ud
Disseminations and Innovation Center for Neuromathematics (grant\ud
2013/07699-0, S. Paulo Research Foundation). NLK is supported by a\ud
FAPESP postdoctoral fellowship (grant 2016/03855-5). ACR is partially\ud
supported by a CNPq fellowship (grant 306251/2014-0)
- âŠ