40,743 research outputs found
Measurement of the ratio of prompt χ c to J / ψ production in pp collisions at √s = 7 TeV
No full textThe prompt production of charmonium χ c and J / ψ states is studied in proton-proton collisions at a centre-of-mass energy of √s = 7 TeV at the Large Hadron Collider. The χ c and J / ψ mesons are identified through their decays χ c → J / ψ γ and J / ψ → μ + μ - using 36 pb - 1 of data collected by the LHCb detector in 2010. The ratio of the prompt production cross-sections for χ c and J / ψ, σ (χ c → J / ψ γ) / σ (J / ψ), is determined as a function of the J / ψ transverse momentum in the range 2 < p T J / ψ < 15 GeV / c. The results are in excellent agreement with next-to-leading order non-relativistic expectations and show a significant discrepancy compared with the colour singlet model prediction at leading order, especially in the low p T J / ψ region
Letter from Carl T. Hayden to C. H. Gensler, Havasupai Reservation
No full textLetter from Carl T. Hayden to C. H. Gensler, Havasupai Indian Reservation, regarding Hualapai and Cataract Canyons geography
Identity and consumption practices of Northamptonshire Caribbeans c.1955-1989
No full textThe objective of this thesis is to delineate and analyse Northamptonshire Caribbeans' consumption c.1955-1989. Author-collected and other oral histories alongside complementary primary and secondary references dovetail to unearth and analyse aspects of Post-War Caribbean consumption in a British provincial location that have been significantly unexplored previously. Central to the argument is the contention that identity is fundamentally significant in comprehending and analysing Northamptonshire Caribbeans' consumption. Various conceptualisations of identity facilitated development of consumer materialisations and aspirations. This thesis explores how multiple forms of identity as Caribbean, Black and British people were significant in shaping local Caribbeans' consumption. The succeeding pages address and analyse how these multiple identities influenced consumption and how provincial consumer behaviour was shaped by Caribbeans' relative co-ethnic isolation in Northamptonshire. Chapter 3 delineates and analyses consumer practices and practicalities of Northamptonshire Caribbeans. Integral within these consumer practices and practicalities are changes in consumption over time, intergenerational differences in consumption, as well as aspects of consumption that could be considered 'typical' and/or 'atypical' Northamptonshire Caribbean consumption; all of which are incorporated within this chapter. Chapter 4 connects identity and consumption through enhancing understanding of Northamptonshire Caribbeans' consumer networks. These networks interacted with the combination of identities local Caribbeans psychologically felt part of within various Caribbean, Black and British permutations. Furthermore, such identities varied more widely amongst the younger generation than their co-ethnic elders, a concept which is also addressed. Education and cultural currency are two novel strands through which to analyse connections between consumption and identity. The final two chapters deploy these concepts in an innovative manner creating and developing greater understanding of Northamptonshire Caribbeans' consumption. Chapter 5 expounds on the concept that education can be used as consumption whilst shaping future consumer behaviour, both ideas significantly under-explored previously. Chapter 6 introduces the theory of cultural currency, the idea that aspects of culture have finite, but changing, values and must be shared to have value similar to monetary currencies having exchange values for other monetary currencies. This chapter demonstrates how Northamptonshire Caribbeans shared aspects of Caribbean culture as cultural currency, fostering co-ethnic strength whilst gaining inter-ethnic respect for Caribbeans. Through comprehending Caribbean identity, correlations between empirical and social history, local consumption, as well as educational and cultural circumstances that stimulated and inspired Northamptonshire Caribbeans, this thesis distinctively illuminates how local Caribbeans' consumption interacted with various permutations of Afro-Caribbean, Black and/or British identities whilst representing idiosyncratic local nodes within these larger amalgamations
A possible mechanism of superconductivity in high-T-c cuprates
No full textThis paper derives a generic T-c formula by using the long-range phase coherence condition in quantum phase fluctuation of the order parameter. Taking the two-local-spin-mediated interaction (TLSMI) proposed by Liu and Chen [Phys. Rev. B 58 (1998) 8812] as a Cooper pair potential, and the T-c formula, this paper explains five basic experimental facts in high-T-c cuprates. The aim of this paper is to show that TLSMI is a possible pairing mechanism of superconductivity in high-T-c cuprates. (C) 2000 Elsevier Science B.V. All rights reserved.Physics, AppliedSCI(E)EI0ARTICLE4276-28434
Memorandum from A. E. Demaray to E. C. Finney
No full textFour letters of correspondence about the purchase of Bright Angel Trail between A. E. Demaray, Acting Director of the Grand Canyon National Park; E. C. Finney, Department of the Interior First Assistant Secretary; Carl T. Hayden, Representative (AZ); and Stephen T. Mather, Director of the National Park Service
Letter from C. T. Woolfolk, Coconino County Board of Supervisors, to Carl Hayden
No full textLetter from C. T. Woolfolk to Carl Hayden expressing his support for the national park bill
Presentation of an Immunodominant Immediate-Early CD8+ T Cell Epitope Resists Human Cytomegalovirus Immunoevasion.
No full textControl of human cytomegalovirus (HCMV) depends on CD8+ T cell responses that are shaped by an individual's repertoire of MHC molecules. MHC class I presentation is modulated by a set of HCMV-encoded proteins. Here we show that HCMV immunoevasins differentially impair T cell recognition of epitopes from the same viral antigen, immediate-early 1 (IE-1), that are presented by different MHC class I allotypes. In the presence of immunoevasins, HLA-A- and HLA-B-restricted T cell clones were ineffective, but HLA-C*0702-restricted T cell clones recognized and killed infected cells. Resistance of HLA-C*0702 to viral immunoevasins US2 and US11 was mediated by the alpha3 domain and C-terminal region of the HLA heavy chain. In healthy donors, HLA-C*0702-restricted T cells dominated the T cell response to IE-1. The same HLA-C allotype specifically protected infected cells from attack by NK cells that expressed a corresponding HLA-C-specific KIR. Thus, allotype-specific viral immunoevasion allows HCMV to escape control by NK cells and HLA-A- and HLA-B-restricted T cells, while the virus becomes selectively vulnerable to an immunodominant population of HLA-C-restricted T cells. Our work identifies a T cell population that may be of particular efficiency in HCMV-specific immunotherapy
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
Heterogeneous and tissue-specific regulation of effector T cell responses by IFN-gamma during Plasmodium berghei ANKA infection.
No full textIFN-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
Wave turbulence of a rotating array of quantized vortices in the T → 0 temperature limit
No full textThe dynamics of quantized vortices in the zero temperature limit is currently of great interest, particularly in the case of the Fermi superfluid He-B. Here we study wave turbulence, generated by the librating motion of a rotating cylindrical container filled with He-B, in the limit of vanishing viscous forces at temperatures . The polarization of the quantized vortices with respect to the axis of rotation is measured using non-invasive NMR techniques. We observe a decrease of the polarization when the librating motion is started, and a two-stage relaxation process when the modulation of the rotation velocity is stopped. The first relaxation process is associated with the dissipation of large-scale flow stored in inertial waves and the solid body rotation of the vortex array. From the decay of these energy reservoirs we determine the rate of energy dissipation of large-scale flow. The later second process is related to the relaxation of Kelvin waves on individual vortices. This process is monitored by the recovery of the polarization. The existence of a Kelvin wave cascade at the lowest temperatures is currently a central open question. We supply some evidence for the cascade
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