40,786 research outputs found
A 2 h periodic variation in the low-mass X-ray binary Ser X-1
No full textSpectroscopy of the low-mass X-ray binary Ser X-1 using the Gran Telescopio Canarias have revealed a ?2 h periodic variability that is present in the three strongest emission lines. We tentatively interpret this variability as due to orbital motion, making it the first indication of the orbital period of Ser X-1. Together with the fact that the emission lines are remarkably narrow, but still resolved, we show that a main-sequence K dwarf together with a canonical 1.4 M? neutron star gives a good description of the system. In this scenario, the most likely place for the emission lines to arise is the accretion disc, instead of a localized region in the binary (such as the irradiated surface or the stream-impact point), and their narrowness is due instead to the low inclination (?10°) of Ser X-1
ExoMol line lists - III. An improved hot rotation-vibration line list for HCN and HNC
No full textA revised rotation-vibration line list for the combined hydrogen cyanide (HCN)/hydrogen isocyanide (HNC) system is presented. The line list uses ab initio transition intensities calculated previously and extensive data sets of recently measured experimental energy levels. The resulting line list has significantly more accurate wavelengths than previous ones for these systems. An improved value for the separation between HCN and HNC is adopted, leading to an approximately 25 per cent lower predicted thermal population of HNC as a function of temperature in the key 2000 to 3000 K region. Temperature-dependent partition functions and equilibrium constants are presented. The line lists are validated by comparison with laboratory spectra and are presented in full as supplementary data to the article and at www.exomol.com
Efficient p-Multigrid Based Solvers for Isogeometric Analysis on Multipatch Geometries
No full textIsogeometric Analysis can be considered as the natural extension of the Finite Element Method (FEM) to higher-order spline based discretizations simplifying the treatment of complex geometries with curved boundaries. Finding a solution of the resulting linear systems of equations efficiently remains, however, a challenging task. Recently, p-multigrid methods have been considered [18], in which a multigrid hierarchy is constructed based on different approximation orders p instead of mesh widths h as it would be the case in classical h-multigrid schemes [8]. The use of an Incomplete LU-factorization as a smoother within the p-multigrid method has shown to lead to convergence rates independent of both h and p for single patch geometries [19]. In this paper, the focus lies on the application of the aforementioned p-multigrid method on multipatch geometries having a C0-continuous coupling between the patches. The use of ILUT as a smoother within p-multigrid methods leads to convergence rates that are essentially independent of h and p, but depend mildly on the number of patches.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Numerical Analysi
Induction of t-cell responses against PSA by plasmid DNA immunization
No full textThis thesis is focused on using plasmid DNA encoding human prostate-specific antigen (PSA) for immunotherapy of prostate cancer. PSA is a secreted serine protease, which is produced almost exclusively by prostate epithelial cells. It is also expressed by prostate epithelial cells after malignant transformation and thus can be considered a tumor-associated antigen for prostate cancer. In our studies we investigated the potency of DNA vaccines to induce PSA-specific CD8+ cytotoxic T lymphocytes (CTLs), which can efficiently target and eliminate PSA-producing tumor cells.In the first study we evaluated the efficacy of PSA-encoding plasmid DNA (pVax-PSA) in inducing T cell responses in patients with hormone-refractory prostate cancer. The plasmid DNA was administered during five cycles in doses of 100, 300 and 900μg, with three patients in each cohort. We demonstrated in this study that the pVax-PSA vaccine given in doses of 900μg is safe and can induce cellular immune responses against PSA.The major aim of the following studies was to characterize the potency of pVax-PSA plasmid in inducing CD8+ T-cell responses in a mouse model. We demonstrated that the pVax-PSA plasmid is highly immunogenic in mice, with just one DNA immunization being sufficient to induce potent CTL responses against PSA. Additional modifications of human PSA, by linking it to heat shock proteins of different origin (pVax-PSA-HSPs plasmids), did not further increased the efficacy of pVax-PSA plasmid in inducing CTL responses or mediating protection against tumor challenge. We have also characterized the epitope specificity of CTLs induced after immunization of C57Bl/6 mice with the pVax-PSA plasmid.We demonstrated that the majority of PSA-specific CTLs were directed against a single H-2Db-restricted epitope HCIRNKSVIL65-74 of PSA. However, immunization of mice with pVax-PSA plasmid does not properly reflect the clinical settings, where endogenous expression of PSA may potentially lead to depletion of high-avidity CD8+ T cell precursors with PSA-specific reactivity. Nevertheless, our findings in this study, will allow us to address this relevant question in experiments with transgenic mice expressing human PSA in prostate tissue, once such model is available on C57Bl/6 background.In the last study, we investigated the role of activation of antigen-presenting cells (APCs) by the plasmid DNA backbone in the induction of CTL responses by DNA vaccines. A single immunization with pVax-PSA plasmid induced stronger CTL responses in wild-type than in TLR9- or MyD88-deficient mice. These results suggest that immunostimulatory activity of CpG-DNA is essential for efficient priming of CTLs after a single DNA immunization.Collectively, our findings demonstrate that DNA vaccines represent a promising modality for induction of PSA-specific T-cell responses. Detailed characterization of immunogenicity of pVax-PSA plasmid in C57Bl/6 mice establishes an experimental background for further evaluation of various strategies to increase its potency in inducing CTL responses in a PSA-transgenic murine model.List of scientific papersI. Pavlenko M, Roos AK, Lundqvist A, Palmborg A, Miller AM, Ozenci V, Bergman B, Egevad L, Hellstrom M, Kiessling R, Masucci G, Wersall P, Nilsson S, Pisa P (2004). A phase I trial of DNA vaccination with a plasmid expressing prostate-specific antigen in patients with hormone-refractory prostate cancer. Br J Cancer. 91(4): 688-94. https://pubmed.ncbi.nlm.nih.gov/15280930II. Pavlenko M, Roos AK, Leder C, Hansson LO, Kiessling R, Levitskaya E, Pisa P (2004). Comparison of PSA-specific CD8+ CTL responses and antitumor immunity generated by plasmid DNA vaccines encoding PSA-HSP chimeric proteins. Cancer Immunol Immunother. 53(12): 1085-92. https://pubmed.ncbi.nlm.nih.gov/15696608III. Pavlenko M, Leder C, Roos AK, Levitsky V, Pisa P (2005). Identification of an immunodominant H-2D(b)-restricted CTL epitope of human PSA. Prostate. 64(1): 50-59. https://pubmed.ncbi.nlm.nih.gov/15651071IV. Pavlenko M, Leder C, Moreno S, Levitsky V, Pisa P (2005). Induction of CTL responses by DNA immunization is improved in TLR9- and MyD88-deficient mice. [Manuscript]</p
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Novel high performance poly(p-phenylene benzobisimidazole) (PBDI) membranes fabricated by interfacial polymerization for H 2 separation
No full text Membranes with high selectivity and permeance are needed to reduce energy consumption in hydrogen purification and pre-combustion CO 2 capture. Polybenzimidazole (PBI) is one of the leading membrane materials for this separation. In this study, we present superior novel supported PBI (poly(p-phenylene benzobisimidazole), PBDI) membranes prepared by a facile interfacial polymerization (IP) method. The effect of IP reaction duration, operating temperature and pressure on membrane separation performance was systematically investigated. The best performance was achieved for membranes prepared in a 2 h reaction time. The resulting membranes display an ultrahigh mixed-gas H 2 /CO 2 selectivity of 23 at 423 K together with an excellent H 2 permeance of 241 GPU, surpassing the membrane performance of conventional polymers (the 2008 Robeson upper bound). These separation results, together with the facile manufacture, pressure resistance, long-term thermostability (>200 h) and economic analysis, recommend the PBDI membranes for industrial use in H 2 purification and pre-combustion CO 2 capture. Besides, PBDI membranes possess high selectivities towards H 2 /N 2 (up to 60) and H 2 /CH 4 (up to 48) mixtures, indicating their potential applications in ammonia synthesis and syngas production. Accepted Author ManuscriptChemE/Catalysis EngineeringOLD ChemE/Organic Materials and InterfacesRST/Storage of Electrochemical Energ
Citations of the author H C Rajpoot
No full textThe list of the articles, research papers, theses, and book chapters globally citing the author H. C. Rajpoot</p
Outsourcing and Skill Imports: Foreign High-Skilled Workers on H-1B and L-1 Visas in the United States
Get PDFThis working paper looks in detail at the H-1B and L-1 visa programs for temporary employment in the United States. Based on official data from the US Citizenship and Immigration Services and the US Department of State, H-1B and L-1 visa issuance rapidly increased in the late 1990s, followed by a marked slowdown after 2001. This points to the highly cyclical nature of both visa programs. Indian nationals and immigrants working in computer-related occupations dominate the H1-B and L-1 population in the United States, but these two groups are also found to be the most cyclical segment, with very large declines in inflows after 2001. The total population of H-1B visaholders in 2003 is estimated to range between 387,000 and 746,000, of which 160,000 to 306,000 were Indian nationals. As all data on H-1B/L-1 visaholders are gross numbers and gross jobs data for comparable categories are absent, the extent of the impact of these visa programs on the US labor market cannot be gauged precisely. A broad range of US industries and educational institutions are found to be employing H-1B recipients, with the IT industry being the dominant sector. Evidence of aggressive wage-cost cutting, including paying H-1B recipients only the legally mandated 95 percent of the prevailing US wage, is found among some H-1B employers, although no systematic abuse of the system is present.Outsourcing, offshoring, high-skilled labor, immigration, H1B/L-1 visas
Fully Turbulent Mean Velocity Profile for Purely Viscous non-Newtonian Fluids
No full textThe characteristic near wall behavior of turbulent flow of purely-viscous non-Newtonian fluids is discussed for both power-law (P.-L.) and Herschel-Bulkley (H.-B.) rheological models. A proper scaling is presented for H.-B. fluids to establish an analogy with power-law fluids with same flow index. To provide reference data for turbulent flow of non-Newtonian fluids, DNS simulations of power-law fluids are conducted in a rectangular channel for a large range of power-law indices ( = 0.5, 0.69, 0.75, 0.9, 1, 1.2). The DNS data show that the mean velocity profile in the viscous and logarithmic layers follow expressions of the form and respectively, where shows a logarithmic dependency on the flow index.Comparison with some experimental data shows the above formulation to be valid for Reynolds numbers (based on shear velocity) as high as 1000
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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