5,758 research outputs found

    Collective dipole excitations in sodium clusters

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    Some properties of small and medium sodium clusters are described within the RPA approach using a projected spherical single particle basis. The oscillator strengths calculated with a Schiff-like dipole transition operator and folded with Lorentzian functions are used to calculate the photoabsorbtion cross section spectra. The results are further employed to establish the dependence of the plasmon frequency on the number of cluster components. Static electric polarizabilities of the clusters excited in a RPA dipole state are also calculated. Comparison of our results with the corresponding experimental data show an overall good agreement.Comment: 23 pages, 5 figure

    The impact of production-dependent geometric properties on fatigue-relevant stresses in laser-welded corrugated core steel sandwich panels

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    For bridge deck applications, laser-welded corrugated core steel sandwich panels with dual weld lines per crest and trough have been shown to be highly material- and economically efficient. The nature of welding induces a variation in the geometric properties of the joint that connects the core to the faces. The geometric properties of the joint are the weld width, weld misalignment, and plate gap between the core and the faces. This paper aims to investigate the impact of the variation of the production-dependent geometric properties of the joint on the fatigue-relevant stresses. A secondary aim of this paper is to investigate the impact of contact between the core and the faces on the weld region stresses. Within this paper, the production of four sandwich panels is documented and the manufacturing-dependent geometric properties of their joints are quantified. In order to investigate the impact of the natural variation of the parameters, a parametric study based on finite element analyses is executed. The result of the parametric study shows, among several other findings, that misalignment of the weld line in relation to the core direction can lead to considerable increases in stresses, determinant for the fatigue life of the panel

    Life Cycle Cost and Life Cycle Assessment of Composite Bridge with Flat and Corrugated Webs

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    To satisfy the sustainability criteria, a bridge design must be economically viable during its entire service life with a minimal impact on the environment. While stainless steel is known for its excellent life cycle performance, its high cost prevents it from being used in bridges to a larger extent. This study evaluates a new design solution that takes advantage of using corrugated web in bridge girders to overcome this issue. Three design concepts are evaluated for a three-span case-study bridge. These include a bridge with carbon steel flat web, stainless steel flat web, and stainless-steel corrugated web girders. Each design is optimized using a genetic algorithm. The three optimal solutions are then evaluated in terms of investment costs, life cycle costs (LCC) and life cycle impact. The results show that the investment costs in a flat web girder bridge increase by 27% when stainless steel is used instead of C-Mn (carbon) steel. However, this increase is only 10% when corrugated web girders are used. On the other hand, the LCC savings increase from 6% to 18% for corrugated web girders. Finally, the use of corrugated web in stainless steel leads to a reduction in the climate impacts of up to 32% compared to carbon steel for the studied bridge

    Colorimetric Measurement of Triglycerides Cannot Provide an Accurate Measure of Stored Fat Content in Drosophila

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    Drosophila melanogaster has recently emerged as a useful model system in which to study the genetic basis of regulation of fat storage. One of the most frequently used methods for evaluating the levels of stored fat (triglycerides) in flies is a coupled colorimetric assay available as a kit from several manufacturers. This is an aqueous-based enzymatic assay that is normally used for measurement of mammalian serum triglycerides, which are present in soluble lipoprotein complexes. In this short communication, we show that coupled colorimetric assay kits cannot accurately measure stored triglycerides in Drosophila. First, they fail to give accurate readings when tested on insoluble triglyceride mixtures with compositions like that of stored fat, or on fat extracted from flies with organic solvents. This is probably due to an inability of the lipase used in the kits to efficiently cleave off the glycerol head group from fat molecules in insoluble samples. Second, the measured final products of the kits are quinoneimines, which absorb visible light in the same wavelength range as Drosophila eye pigments. Thus, when extracts from crushed flies are assayed, much of the measured signal is actually due to eye pigments. Finally, the lipoprotein lipases used in colorimetric assays also cleave non-fat glycerides. The glycerol backbones liberated from all classes of glycerides are measured through the remaining reactions in the assay. As a consequence, when these assay kits are used to evaluate tissue extracts, the observed signal actually represents the amount of free glycerols together with all types of glycerides. For these reasons, findings obtained through use of coupled colorimetric assays on Drosophila samples must be interpreted with caution. We also show here that using thin-layer chromatography to measure stored triglycerides in flies eliminates all of these problems

    Cross sections for Coulomb and nuclear breakup of three-body halo nuclei

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    All possible dissociation cross sections for the loosely bound three-body halo nuclei 6^6He (n+n+α\alpha) and 11^{11}Li (n+n+9^{9}Li) are computed as functions of target and beam energy. Both Coulomb and nuclear interactions are included in the same theoretical framework. The measurements agree with the calculations for energies above 100 Mev/nucleon. The largest cross sections correspond to final states with zero or three particles for heavy and with two neutrons for light targets.Comment: 5 pages, 3 figures, revte

    Study protocol for the OligoMetastatic Esophagogastric Cancer (OMEC) project: A multidisciplinary European consensus project on the definition and treatment for oligometastatic esophagogastric cancer

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    BACKGROUND A uniform definition and treatment for oligometastatic esophagogastric cancer is currently lacking. However, a comprehensive definition of oligometastatic esophagogastric cancer is necessary to initiate studies on local treatment strategies (e.g. metastasectomy or stereotactic radiotherapy) and new systemic therapy agents in this group of patients. For this purpose, the OligoMetastatic Esophagogastric Cancer (OMEC) project was established. The OMEC-project aims to develop a multidisciplinary European consensus statement on the definition, diagnosis, and treatment for oligometastatic esophagogastric cancer and provide a framework for prospective studies to improve outcomes of these patients. METHODS The OMEC-project consists of five studies, including 1) a systematic review on definitions and outcomes of oligometastatic esophagogastric cancer; 2) real-life clinical scenario discussions in multidisciplinary expert teams to determine the variation in the definition and treatment strategies; 3) Delphi consensus process through a starting meeting, two Delphi questionnaire rounds, and a consensus meeting; 4) publication of a multidisciplinary European consensus statement; and 5) a prospective clinical trial in patients with oligometastatic esophagogastric cancer. DISCUSSION The OMEC project aims to establish a multidisciplinary European consensus statement for oligometastatic esophagogastric cancer and aims to initiate a prospective clinical trial to improve outcomes for these patients. Recommendations from OMEC can be used to update the relevant guidelines on treatment for patients with (oligometastatic) esophagogastric cancer

    Competition in rotation-alignment between high-j neutrons and protons in transfermium nuclei

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    The study of rotation-alignment of quasiparticles probes sensitively the properties of high-j intruder orbits. The distribution of very high-j orbits, which are consequences of the fundamental spin-orbit interaction, links with the important question of single-particle levels in superheavy nuclei. With the deformed single-particle states generated by the standard Nilsson potential, we perform Projected-Shell-Model calculations for transfermium nuclei where detailed spectroscopy experiment is currently possible. Specifically, we study the systematical behavior of rotation-alignment and associated band-crossing phenomenon in Cf, Fm, and No isotopes. Neutrons and protons from the high-j orbits are found to compete strongly in rotation-alignment, which gives rise to testable effects. Observation of these effects will provide direct information on the single-particle states in the heaviest nuclear mass region.Comment: 9 pages, 5 figure

    Definition of oligometastatic esophagogastric cancer and impact of local oligometastasis-directed treatment: A systematic review and meta-analysis

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    BACKGROUND Local treatment (metastasectomy or stereotactic radiotherapy) for oligometastatic disease (OMD) in patients with esophagogastric cancer may improve overall survival (OS). The primary aim was to identify definitions of esophagogastric OMD. A secondary aim was to perform a meta-analysis of OS after local treatment versus systemic therapy alone for OMD. METHODS Studies and study protocols reporting on definitions or OS after local treatment for esophagogastric OMD were included. The primary outcome was the maximum number of organs/lesions considered OMD and the maximum number of lesions per organ (i.e. 'organ-specific' OMD burden). Agreement was considered to be either absent/poor (< 50%), fair (50%-75%), or consensus (≥ 75%). The secondary outcome was the pooled adjusted hazard ratio (aHR) for OS after local treatment versus systemic therapy alone. The ROBINS tool was used for quality assessment. RESULTS A total of 97 studies, including 7 study protocols, and 2 prospective studies, were included. OMD was considered in 1 organ with ≤ 3 metastases (consensus). 'Organ-specific' OMD burden could involve bilobar ≤ 3 liver metastases, unilateral ≤ 2 lung metastases, 1 extra-regional lymph node station, ≤ 2 brain metastases, or bilateral adrenal gland metastases (consensus). Local treatment for OMD was associated with improved OS compared with systemic therapy alone based on 6 non-randomized studies (pooled aHR 0.47, 95% CI: 0.30-0.74) and for liver oligometastases based on 5 non-randomized studies (pooled aHR 0.39, 95% CI: 0.22-0.59). All studies scored serious risk of bias. CONCLUSIONS Current literature considers esophagogastric cancer spread limited to 1 organ with ≤ 3 metastases or 1 extra-regional lymph node station to be OMD. Local treatment for OMD appeared associated with improved OS compared with systemic therapy alone. Prospective randomized trials are warranted

    Haemophilus influenzae surface fibril (Hsf) is a unique twisted hairpin-like trimeric autotransporter.

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    The Haemophilus surface fibril (Hsf) is an extraordinary large (2413 amino acids) trimeric autotransporter, present in all encapsulated Haemophilus influenzae. It contributes to virulence by directly functioning as an adhesin. Furthermore, Hsf recruits the host factor vitronectin thereby inhibiting the host innate immune response resulting in enhanced survival in serum. Here we observed by electron microscopy that Hsf appears as an 100nm long fibril at the bacterial surface albeit the length is approximately 200nm according to a bioinformatics based model. To unveil this discrepancy, we denaturated Hsf at the surface of Hib by using guanidine hydrochloride (GuHCl). Partial denaturation induced in the presence of GuHCl unfolded the Hsf molecules, and resulted in an increased length of fibres in comparison to the native trimeric form. Importantly, our findings were also verified by E. coli expressing Hsf at its surface. In addition, a set of Hsf-specific peptide antibodies also indicated that the N-terminal of Hsf is located near the C-terminal at the base of the fibril. Taken together, our results demonstrated that Hsf is not a straight molecule but is folded and doubled over. This is the first report that provides the unique structural features of the trimeric autotransporter Hsf
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