5,072 research outputs found
Construction productivity analysis for asphalt concrete pavement rehabilitation in urban corridors
The results of a constructibility and productivity analysis for the California Department of Transportation Long Life Asphalt Concrete Pavement Rehabilitation Strategies program are presented. With the assistance of California asphalt concrete (AC) paving contractors, the analysis explored the effects on construction productivity of rehabilitation materials, design strategy (crack seat and overlay, full-depth replacement), layer profiles, AC cooling time, resource constraints, and alternative lane closure tactics. Deterministic and stochastic analysis programs were developed. A sensitivity study that examined the construction production capability within a 55-h weekend closure was performed. Weekend closures were also compared with continuous closures. Demolition and AC delivery truck flows were the major constraints limiting the AC rehabilitation production capability. It was concluded from the study that efficient lane closure tactics designed to work with the pavement profile (an minimize the nonworking time to increase the construction product! on efficiency. The results of the study will help road agencies evaluate rehabilitation strategies and tactics with the goal of balancing the maximization of production capability and minimization of traffic delay during urban pavement rehabilitation.open114sciescopu
Morphology of Vaccine RD&D translation
Translation as a concept coordinates participation in innovation but remains
a qualitative construct. We provide multivariate accounting of linkages between
market entries of vaccines, clinical trials, patents, publications, funders,
and grants to quantify biomedical translation. We found that the most prevalent
types of biomedical translation are those between basic and applied research
(52 percent) followed by those between research and product development (36
percent). Although many biomedical stakeholders assume knowledge flows one way
from upstream research to downstream application, knowledge feedbacks that
mediate translation are prevalent. We also cluster biomedical funders based on
the types of translations they fund. Large-scale funding agencies such as NIH
are similarly involved in early-stage translation, whereas pharmaceuticals and
mission-oriented agencies such as DARPA involve diverse translation types, and
each leaves different translation footprints
Recent advances in electronic structure theory and their influence on the accuracy of ab initio potential energy surfaces
Recent advances in electronic structure theory and the availability of high speed vector processors have substantially increased the accuracy of ab initio potential energy surfaces. The recently developed atomic natural orbital approach for basis set contraction has reduced both the basis set incompleteness and superposition errors in molecular calculations. Furthermore, full CI calculations can often be used to calibrate a CASSCF/MRCI approach that quantitatively accounts for the valence correlation energy. These computational advances also provide a vehicle for systematically improving the calculations and for estimating the residual error in the calculations. Calculations on selected diatomic and triatomic systems will be used to illustrate the accuracy that currently can be achieved for molecular systems. In particular, the F+H2 yields HF+H potential energy hypersurface is used to illustrate the impact of these computational advances on the calculation of potential energy surfaces
Direct photon production with effective field theory
The production of hard photons in hadronic collisions is studied using
Soft-Collinear Effective Theory (SCET). This is the first application of SCET
to a physical, observable cross section involving energetic partons in more
than two directions. A factorization formula is derived which involves a
non-trivial interplay of the angular dependence in the hard and soft functions,
both quark and gluon jet functions, and multiple partonic channels. The
relevant hard, jet and soft functions are computed to one loop and their
anomalous dimensions are determined to three loops. The final resummed
inclusive direct photon distribution is valid to next-to-next-to-leading
logarithmic order (NNLL), one order beyond previous work. The result is
improved by including non-logarithmic terms and photon isolation cuts through
matching, and compared to Tevatron data and to fixed order results at the
Tevatron and the LHC. The resummed cross section has a significantly smaller
theoretical uncertainty than the next-to-leading fixed-order result,
particularly at high transverse momentum.Comment: 42 pages, 9 figures; v2: references added, minor changes; v3: typos;
v4: typos, corrections in (16), (47), (72
Factorization and resummation of s-channel single top quark production
In this paper we study the factorization and resummation of s-channel single
top quark production in the Standard Model at both the Tevatron and the LHC. We
show that the production cross section in the threshold limit can be factorized
into a convolution of hard function, soft function and jet function via
soft-collinear-effective-theory (SCET), and resummation can be performed using
renormalization group equation in the momentum space resummation formalism. We
find that in general, the resummation effects enhance the Next-to-Leading-Order
(NLO) cross sections by about at both the Tevatron and the LHC, and
significantly reduce the factorization scale dependence of the total cross
section at the Tevatron, while at the LHC we find that the factorization scale
dependence has not been improved, compared with the NLO results.Comment: 29 pages, 7 figures; version published in JHE
Towards a safe and effective chlamydial vaccine: lessons from the eye.
As well as being the most common bacterial sexually transmitted infection, Chlamydia trachomatis (Ct) is the leading infectious cause of blindness. The pathogenesis of ocular chlamydial infection (trachoma) is similar to that of genital infection. In the 1960s the efficacy of Ct vaccines against ocular infection was evaluated in major field trials in Saudi Arabia, Taiwan, The Gambia, India and Ethiopia. These trials showed that it was possible to induce short term immunity to ocular infection, and to reduce the incidence of inflammatory trachoma, by parenteral immunisation with killed or live whole organism vaccines. In one study, it was also shown that the incidence of scarring sequelae was reduced in vaccinated children. Detailed studies in non-human primates conducted at this time suggested that vaccination could lead to more severe inflammatory disease on subsequent challenge. Since that time there have been many studies on the immunological correlates of protective immunity and immunopathology in ocular Ct infection in humans and non-human primates, and on host genetic polymorphisms associated with protection from adverse sequelae. These have provided important information to guide the development and evaluation of a human Ct vaccine
InGaN nano-ring structures for high-efficiency light emitting diodes
A technique based on the Fresnel diffraction effect for the fabrication of nano-scale site-controlled ring structures in InGaN/GaN multi-quantum well structures has been demonstrated. The ring structures have an internal diameter of 500 nm and a wall width of 300 nm. A 1 cm-1 Raman shift has been measured, signifying substantial strain relaxation from the fabricated structure. The 9 nm blueshift observed in the cathodoluminescence spectra can be attributed to band filling and/or screening of the piezoelectric field. A light emitting diode based on this geometry has been demonstrated. © 2005 American Institute of Physics.published_or_final_versio
Systemic Effector and Regulatory Immune Responses to Chlamydial Antigens in Trachomatous Trichiasis
Trachomatous trichiasis (TT) caused by repeated or chronic ocular infection with Chlamydia trachomatis is the result of a pro-fibrotic ocular immune response. At the conjunctiva, the increased expression of both inflammatory (IL1B, TNF) and regulatory cytokines (IL10) have been associated with adverse clinical outcomes. We measured in vitro immune responses of peripheral blood to a number of chlamydial antigens. Peripheral blood effector cells (CD4, CD69, IFNγ, IL-10) and regulatory cells (CD4, CD25, FOXP3, CTLA4/GITR) were readily stimulated by C. trachomatis antigens but neither the magnitude (frequency or stimulation index) or the breadth and amount of cytokines produced in vitro [IL-5, IL-10, IL-12 (p70), IL-13, IFNγ, and TNFα] were significantly different between TT cases and their non-diseased controls. Interestingly we observed that CD4+ T cells account for <50% of the IFNγ positive cells induced following stimulation. Further investigation in individuals selected from communities where exposure to ocular infection with C. trachomatis is endemic indicated that CD3−CD56+ (classical natural killer cells) were a major early source of IFNγ production in response to C. trachomatis elementary body stimulation and that the magnitude of this response increased with age. Future efforts to unravel the contribution of the adaptive immune response to conjunctival fibrosis should focus on the early events following infection and the interaction with innate immune mediated mechanisms of inflammation in the conjunctiva
Anisotropic Structure of the Order Parameter in FeSe0.45Te0.55 Revealed by Angle Resolved Specific Heat
The symmetry and structure of the superconducting gap in the Fe-based
superconductors are the central issue for understanding these novel materials.
So far the experimental data and theoretical models have been highly
controversial. Some experiments favor two or more constant or nearly-constant
gaps, others indicate strong anisotropy and yet others suggest gap zeros
("nodes"). Theoretical models also vary, suggesting that the absence or
presence of the nodes depends quantitatively on the model parameters. An
opinion that has gained substantial currency is that the gap structure, unlike
all other known superconductors, including cuprates, may be different in
different compounds within the same family. A unique method for addressing this
issue, one of the very few methods that are bulk and angle-resolved, calls for
measuring the electronic specific heat in a rotating magnetic field, as a
function of field orientation with respect to the crystallographic axes. In
this Communication we present the first such measurement for an Fe-based
high-Tc superconductor (FeBSC). We observed a fourfold oscillation of the
specific heat as a function of the in-plane magnetic field direction, which
allowed us to identify the locations of the gap minima (or nodes) on the Fermi
surface. Our results are consistent with the expectations of an extended s-wave
model with a significant gap anisotropy on the electron pockets and the gap
minima along the \Gamma M (or Fe-Fe bond) direction.Comment: 32 pages, 7 figure
Early (and Later) LHC Search Strategies for Broad Dimuon Resonances
Resonance searches generally focus on narrow states that would produce a
sharp peak rising over background. Early LHC running will, however, be
sensitive primarily to broad resonances. In this paper we demonstrate that
statistical methods should suffice to find broad resonances and distinguish
them from both background and contact interactions over a large range of
previously unexplored parameter space. We furthermore introduce an angular
measure we call ellipticity, which measures how forward (or backward) the muon
is in eta, and allows for discrimination between models with different parity
violation early in the LHC running. We contrast this with existing angular
observables and demonstrate that ellipticity is superior for discrimination
based on parity violation, while others are better at spin determination.Comment: 31 pages, 19 figures. References added, minor modifications made to
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