56 research outputs found
Comments on gluon scattering amplitudes via AdS/CFT
In this article we consider n gluon color ordered, planar amplitudes in N=4
super Yang Mills at strong 't Hooft coupling. These amplitudes are approximated
by classical surfaces in AdS_5 space. We compute the value of the amplitude for
a particular kinematic configuration for a large number of gluons and find that
the result disagrees with a recent guess for the exact value of the amplitude.
Our results are still compatible with a possible relation between amplitudes
and Wilson loops.
In addition, we also give a prescription for computing processes involving
local operators and asymptotic states with a fixed number of gluons. As a
byproduct, we also obtain a string theory prescription for computing the dual
of the ordinary Wilson loop, Tr P exp[ i\oint A ], with no couplings to the
scalars. We also evaluate the quark-antiquark potential at two loops.Comment: 27 pages, 9 figures,v3:minor correction
Comments on gluon 6-point scattering amplitudes in N=4 SYM at strong coupling
We use the AdS/CFT prescription of Alday and Maldacena \cite{am} to analyze
gluon 6-point scattering amplitudes at strong coupling in SYM. By
cutting and gluing we obtain AdS 6-point amplitudes that contain extra boundary
conditions and come close to matching the field theory results. We interpret
them as parts of the field theory amplitudes, containing only certain diagrams.
We also analyze the collinear limits of 6- and 5-point amplitudes and discuss
the results.Comment: 35 pages, 7 figures, latex, references adde
Light propagation in non-trivial QED vacua
Within the framework of effective action QED, we derive the light cone
condition for homogeneous non-trivial QED vacua in the geometric optics
approximation. Our result generalizes the ``unified formula'' suggested by
Latorre, Pascual and Tarrach and allows for the calculation of velocity shifts
and refractive indices for soft photons travelling through these vacua.
Furthermore, we clarify the connection between the light velocity shift and the
scale anomaly. This study motivates the introduction of a so-called effective
action charge that characterizes the velocity modifying properties of the
vacuum. Several applications are given concerning vacuum modifications caused
by, e.g., strong fields, Casimir systems and high temperature.Comment: 13 pages, REVTeX, 3 figures, to appear in Phys. Rev.
Candidalysin is required for neutrophil recruitment and virulence during systemic Candida albicans infection
Background
Candidalysin is a cytolytic peptide toxin secreted by Candida albicans hyphae and has significantly advanced our understanding of fungal pathogenesis. Candidalysin is critical for mucosal C albicans infections and is known to activate epithelial cells to induce downstream innate immune responses that are associated with protection or immunopathology during oral or vaginal infections. Furthermore, candidalysin activates the NLRP3 inflammasome and causes cytolysis in mononuclear phagocytes. However, the role of candidalysin in driving systemic infections is unknown.
Methods
In this study, using candidalysin-producing and candidalysin-deficient C albicans strains, we show that candidalysin activates mitogen-activated protein kinase (MAPK) signaling and chemokine secretion in endothelial cells in vitro.
Results
Candidalysin induces immune activation and neutrophil recruitment in vivo, and it promotes mortality in zebrafish and murine models of systemic fungal infection.
Conclusions
The data demonstrate a key role for candidalysin in neutrophil recruitment and fungal virulence during disseminated systemic C albicans infections
Neutrino Propagation in a Strongly Magnetized Medium
We derive general expressions at the one-loop level for the coefficients of
the covariant structure of the neutrino self-energy in the presence of a
constant magnetic field. The neutrino energy spectrum and index of refraction
are obtained for neutral and charged media in the strong-field limit () using the lowest Landau level
approximation. The results found within the lowest Landau level approximation
are numerically validated, summing in all Landau levels, for strong and weakly-strong fields. The neutrino energy in
leading order of the Fermi coupling constant is expressed as the sum of three
terms: a kinetic-energy term, a term of interaction between the magnetic field
and an induced neutrino magnetic moment, and a rest-energy term. The leading
radiative correction to the kinetic-energy term depends linearly on the
magnetic field strength and is independent of the chemical potential. The other
two terms are only present in a charged medium. For strong and weakly-strong
fields, it is found that the field-dependent correction to the neutrino energy
in a neutral medium is much larger than the thermal one. Possible applications
to cosmology and astrophysics are considered.Comment: 23 pages, 4 figures. Corrected misprints in reference
Association Between HIV and Prevalence and Manifestations of Asthma: Analysis of the Multicenter AIDS Cohort Study and Women's Interagency HIV Study
Background:The association between HIV and asthma prevalence and manifestations remains unclear, with few studies including women.Setting:A retrospective observational cohort study from the Multicenter AIDS Cohort Study and Women's Interagency HIV Study.Methods:Asthma was defined in 2 ways: (1) self-report and (2) robust criteria requiring all the following: lack of fixed airflow obstruction, presence of wheeze on the St. George's Respiratory Questionnaire (SGRQ), and report of asthma therapies. Estimates of asthma prevalence and asthma-related manifestations were compared by HIV serostatus.Results:A total of 1815 men and 2122 women were included. Asthma prevalence did not differ between people with HIV (PWH) and people without HIV regardless of definition: self-report (men, 12.0% vs. 11.2%; women, 24.3% vs. 27.5%) and robust criteria (men, 5.0% vs. 3.4%; women, 12.8% vs. 13.2%). Among men with asthma, worse respiratory symptom burden was reported among those with HIV, regardless of asthma definition. Among women with self-reported asthma, those with HIV had less respiratory symptom burden. Regardless of serostatus, women with robust-defined asthma had similar respiratory symptoms across SGRQ domains and similar frequencies of phlegm, shortness of breath, and wheezing.Conclusions:Among PWH and people without HIV, asthma prevalence was 2-fold to 3-fold higher using self-reported definition rather than robust definition. In men and women, HIV was not associated with increased asthma prevalence. In men, HIV was associated with more respiratory symptoms when asthma was self-reported; the relationship was attenuated with the robust criteria. Further studies are needed to explore asthma phenotypes among PWH
Early and Late-time Cosmic Acceleration in Non-minimal Yang-Mills- Gravity
In this paper we show that power-law inflation can be realized in non-minimal
gravitational coupling of Yang-Mills field with a general function of the
Gauss-Bonnet invariant in the framework of Einstein gravity. Such a non-minimal
coupling may appear due to quantum corrections. We also discuss the non-minimal
Yang-Mills- gravity in the framework of modified Gauss-Bonnet action
which is widely studied recently. It is shown that both inflation and late-time
cosmic acceleration are possible in such a theory.Comment: 13 pages, no figures, v2 references added, Minor typos correcte
Use of SMS texts for facilitating access to online alcohol interventions: a feasibility study
A41 Use of SMS texts for facilitating access to online alcohol interventions: a feasibility study
In: Addiction Science & Clinical Practice 2017, 12(Suppl 1): A4
The effectiveness of flower strips and hedgerows on pest control, pollination services and crop yield: a quantitative synthesis
Floral plantings are promoted to foster ecological intensification of agriculture through provisioning of ecosystem services. However, a comprehensive assessment of the effectiveness of different floral plantings, their characteristics and consequences for crop yield is lacking. Here we quantified the impacts of flower strips and hedgerows on pest control (18 studies) and pollination services (17 studies) in adjacent crops in North America, Europe and New Zealand. Flower strips, but not hedgerows, enhanced pest control services in adjacent fields by 16% on average. However, effects on crop pollination and yield were more variable. Our synthesis identifies several important drivers of variability in effectiveness of plantings: pollination services declined exponentially with distance from plantings, and perennial and older flower strips with higher flowering plant diversity enhanced pollination more effectively. These findings provide promising pathways to optimise floral plantings to more effectively contribute to ecosystem service delivery and ecological intensification of agriculture in the future
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