21,923 research outputs found
Heterogeneous and tissue-specific regulation of effector T cell responses by IFN-gamma during Plasmodium berghei ANKA infection.
Get PDFIFN-γ and T cells are both required for the development of experimental cerebral malaria during Plasmodium berghei ANKA infection. Surprisingly, however, the role of IFN-γ in shaping the effector CD4(+) and CD8(+) T cell response during this infection has not been examined in detail. To address this, we have compared the effector T cell responses in wild-type and IFN-γ(-/-) mice during P. berghei ANKA infection. The expansion of splenic CD4(+) and CD8(+) T cells during P. berghei ANKA infection was unaffected by the absence of IFN-γ, but the contraction phase of the T cell response was significantly attenuated. Splenic T cell activation and effector function were essentially normal in IFN-γ(-/-) mice; however, the migration to, and accumulation of, effector CD4(+) and CD8(+) T cells in the lung, liver, and brain was altered in IFN-γ(-/-) mice. Interestingly, activation and accumulation of T cells in various nonlymphoid organs was differently affected by lack of IFN-γ, suggesting that IFN-γ influences T cell effector function to varying levels in different anatomical locations. Importantly, control of splenic T cell numbers during P. berghei ANKA infection depended on active IFN-γ-dependent environmental signals--leading to T cell apoptosis--rather than upon intrinsic alterations in T cell programming. To our knowledge, this is the first study to fully investigate the role of IFN-γ in modulating T cell function during P. berghei ANKA infection and reveals that IFN-γ is required for efficient contraction of the pool of activated T cells
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
DNA fusion gene vaccination mobilizes effective anti-leukemic cytotoxic T lymphocytes from a tolerized repertoire
No full textThe majority of known human tumor-associated antigens derive from non-mutated self proteins. T cell tolerance, essential to prevent autoimmunity, must therefore be cautiously circumvented to generate cytotoxic T cell responses against these targets. Our strategy uses DNA fusion vaccines to activate high levels of peptide-specific CTL. Key foreign sequences from tetanus toxin activate tolerance-breaking CD4+ T cell help. Candidate MHC class Ibinding tumor peptide sequences are fused to the C terminus for optimal processing and presentation. To model performance against a leukemia-associated antigen in a tolerized setting, we constructed a fusion vaccine encoding an immunodominant CTL epitopederived from Friend murine leukemia virus gag protein (FMuLVgag) and vaccinated tolerant FMuLVgag-transgenic (gag-Tg) mice. Vaccination with the construct induced epitopespecificIFN-c-producing CD8+ T cells in normal and gag-Tg mice. The frequency and avidity of activated cells were reduced in gag-Tg mice, and no autoimmune injury resulted. However, these CD8+ T cells did exhibit gag-specific cytotoxicity in vitro and in vivo. Also, epitope-specific CTL killed FBL-3 leukemia cells expressing endogenous FMuLVgag antigen and protected against leukemia challenge in vivo. These results demonstrate a simple strategy to engage anti-microbial T cell help to activate epitope-specific polyclonal CD8+ T cell responses from a residual tolerized repertoire
Acoustic radiation due to scattering of T-S wave by the mean-flow distortion induced by steady local suction
No full textSubstantial sound waves can be generated by boundary-layer instability modes when the latter are scattered by a rapid mean-flow distortion. This is a rather generic mechanism and operates when an oncoming T-S wave is scattered by a steady local suction slot. This paper focuses on this problem by extending a recently developed Local Scattering Theory (Wu & Dong, J. Fluid Mech. submitted), where a so-called transmission coefficient, defined as the ratio of the T-S wave amplitude downstream of the scatter to that upstream, is introduced to characterize the effect of a local scatter on boundary-layer instability and transition. As in the earlier work, the mathematical formulation is based on triple-deck formulism, but in order to accommodate the acoustic far field, which was not considered in the paper mentioned, the unsteady terms in the upper deck, which play a leading-order role in radiation, are retained, and the influence of the radiated sound on the near-wall perturbation is included. The upper deck equation for the pressure is the Helmholtz equation rather than the Laplace equation. This leads to a modified pressure-displacement relation, which is coupled with the linearized boundary-layer equations in the lower deck. Discretization of the whole system formulates a generalized eigenvalue problem, which is solved numerically. It is found that suction suppresses oncoming T-S waves, and this effect increases with the suction velocity and the slot width. The directivity is ndependent of the flow parameters only when the Mach number is low. The intensity of the radiated sound in general increases with the frequency, the suction velocity and the width of the suction slot. Interestingly, for O(1) suction velocities, the radiated sound is very weak, indicating that the gain of stabilizing effect does not cause aeroacoustic penalty
Exploiting knowledge of immune selection in HIV-1 to detect HIV-specific CD8 T-cell responses
Get PDFSince HLA-restricted cytotoxic T-cell responses select specific polymorphisms in HIV-1 sequences and HLA diversity is relatively static in human populations, we investigated the use of peptide epitopes based on sites of HLA-associated adaptation in HIV-1 sequences to stimulate and detect T-cell responses ex vivo. These "HLA-optimised" peptides captured more HIV-1 Nef-specific responses compared with overlapping peptides of a single consensus sequence, in interferon-γ enzyme linked immunospot assays. Sites of immune selection can reveal more immunogenic epitopes in HLA-diverse populations and offer insights into the nature of HLA-epitope targeting, which could be applied in vaccine design
Self-archiving practice and the influence of publisher policies in the social sciences
No full textAuthors in different disciplines exhibit very different behaviours on the so-called ‘green’ road to open access, i.e. self-archiving. This study looks at the self-archiving behaviour of authors publishing in leading journals in six social science disciplines. It tests the hypothesis that authors are self-archiving according to the norms of their respective disciplines rather than following self-archiving policies of publishers, and that, as a result, they are self-archiving significant numbers of publisher PDF versions. It finds significant levels of
self-archiving, as well as significant self-archiving of
the publisher PDF version, in all the disciplines
investigated. Publishers’ self-archiving policies have
no influence on author self-archiving practice
Optimisation of a Photovoltaic-Thermal (PV-T) panel for Desalination
No full textWater stress levels are rising due to industrialisation and the increase in population. With the freshwater supplies depleting at a rate faster than the refreshment rate, there is a need to look into unconventional and sustainable sources of water. Desalination technology is a reliable solution for the future water requirement; however, it is an energy-intensive process. Desalination is mostly powered by fossil fuels and there is a need to move away from these. For this reason, a Photovoltaic Thermal (PV-T) powered desalination plant which uses the Multi-effect Distillation (MED) coupled with Mechanical Vapour Compression (MVC) technology, is investigated. A novel design of the PV-T module is used wherein a water reservoir is attached directly to the back of a PV module.The PV-T module produces electrical and thermal energy simultaneously, which are the required inputs to a MED-MVC desalination system. To have the desalination system working efficiently, it is important to predict the output from the module with respect to its design and the location weather parameters. To predict the output water temperature with varying weather conditions, a PV-T model was built using COMSOL Multiphysics. The model was validated using experimental data from the location of Dubai. It is found that the water outlet temperature and the total efficiency of the module vary with its inclination angle and flow rate of water through it. With a sensitivity analysis for the outlet water temperature and the total efficiency with respect to tilt angle and flow rate, optimum values for these parameters are obtained for summer and winter days. A maximum water outlet temperature of 91o C in summer and 58 o C in winter is predicted from the model, for the Dubai location, for these optimum values. Using experimental and simulated results, output parameters such as water outlet temperature at a given flow rate is predicted using dimensionless numbers which characterises the PV-T design and the surrounding environment that the system is placed in. The hot water from the PV-T array which consists of 400 PV-T panels is used to produce steam using flash evaporation, for thermal input to the MED vessel. Sensitivity analysis for the temperature and quantity of the hot water produced from the array showed that a maximum amount of steam of 1782 kg can be produced on a summer day with a water outlet temperature of 85 o C. Due to lower water outlet temperature in winter, heating elements should be used to raise the water temperature to 85 o C. The maximum amount of steam produced, as a result of 85 deg C water temperature, will lead to 6058 kg of distilled water per day when used as input to the MED with 4 effects. According to water requirement, additional steam can be produced by the MVC.<br/
Author Classifications of O*NET Individual Work Activities (IWA)
No full text<p>Author Classifications of O*NET Individual Work Activities (IWA) used in "Innovations and Economic Output Scale with Social Interactions in the Workforce"</p>
The 2-dimensional nonlinear Schrödinger–Maxwell system
No full textIn this paper we carry on the study of a system recently introduced by the first author as the planar version of the well known electrostatic Schrodinger-Maxwell equations. In the positive potential case, we exhibit situations where the existence of solutions depends on the strength of the coupling, being this one modulated by a parameter. We also present some results in the case of a sign-changing potential. (c) 2023 Elsevier Ltd. All rights reserved
Ejaculate characteristics of sheep infected with Trypanosoma brucei and T vivax: changes caused by treatment with diminazene aceturate
No full textThe effect of Trypanosoma brucei and T vivax on the ejaculate of sheep and the rate of recovery with diminazene aceturate treatment was investigated. Animals were made to ejaculate once a week before infection, during infection and after treatment. Parameters studied were semen volume, semen colour, sperm motility and concentration, percentage dead spermatozoa and sperm morphology. Both infections severely affected the quality of the ejaculate although in T vivax infection there was no appreciable change in semen volume and sperm concentration. There was a reduction in sperm motility and concentration, an increase in the percentage of dead spermatozoa and in abnormal sperm morphology. Treatment led to improvement in all parameters but recovery was faster in T vivax than in T brucei infection. Ejaculate with few primary abnormalities was not obtained until 19 weeks after treatment.LR: 20031114; PUBM: Print; JID: 0401300; 0 (Trypanocidal Agents); 536-71-0 (Diminazene); 908-54-3 (diminazene aceturate); ppublishSource type: Electronic(1
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