642 research outputs found
Radiative corrections to W-boson hadroproduction: higher-order electroweak and supersymmetric effects
The high accuracy envisaged for future measurements of W-boson production at
hadron colliders has to be matched by precise theoretical predictions. We study
the impact of electroweak radiative corrections on W-boson production cross
sections and differential distributions at the Tevatron and at the LHC. In
particular, we include photon-induced processes, which contribute at O(alpha),
and leading radiative corrections beyond O(alpha) in the high-energy Sudakov
regime and from multi-photon final-state radiation. We furthermore present the
calculation of the complete supersymmetric next-to-leading-order electroweak
and QCD corrections to W-boson hadroproduction within the MSSM. The
supersymmetric corrections turn out to be negligible in the vicinity of the W
resonance in general, reaching the percent level only at high lepton transverse
momentum and for specific choices of the supersymmetric parameters.Comment: 30 pages, 10 figures, 2 new sections, including a comparison with
previous results on multi-photon radiation; version published in PR
FoodLAND (FOOD and Local Agricultural, and Nutritional Diversity) Project, Multi-actor centres of innovation for urban and rural food systems in selected African Countries
The phase portrait of a matter bounce in Horava-Lifshitz cosmology
The occurrence of a bounce in FRW cosmology requires modifications of general
relativity. An example of such a modification is the recently proposed
Horava-Lifshitz theory of gravity, which includes a ``dark radiation'' term
with a negative coefficient in the analog of the Friedmann equation. This paper
describes a phase space analysis of models of this sort with the aim of
determining to what extent bouncing solutions can occur. A simplification,
valid in the relevant region, allows a reduction of the dimension of phase
space so that visualization in three dimensions is possible. It is found that a
bounce is possible, but not generic in models under consideration. Apart from
previously known bouncing solutions some new ones are also described. Other
interesting solutions found include ones which describe a novel sort of
oscillating universes.Comment: 14 pages, 8 figure
Agile SoC Development with Open ESP
ESP is an open-source research platform for heterogeneous SoC design. The
platform combines a modular tile-based architecture with a variety of
application-oriented flows for the design and optimization of accelerators. The
ESP architecture is highly scalable and strikes a balance between regularity
and specialization. The companion methodology raises the level of abstraction
to system-level design and enables an automated flow from software and hardware
development to full-system prototyping on FPGA. For application developers, ESP
offers domain-specific automated solutions to synthesize new accelerators for
their software and to map complex workloads onto the SoC architecture. For
hardware engineers, ESP offers automated solutions to integrate their
accelerator designs into the complete SoC. Conceived as a heterogeneous
integration platform and tested through years of teaching at Columbia
University, ESP supports the open-source hardware community by providing a
flexible platform for agile SoC development.Comment: Invited Paper at the 2020 International Conference On Computer Aided
Design (ICCAD) - Special Session on Opensource Tools and Platforms for Agile
Development of Specialized Architecture
Compactifying the state space for alternative theories of gravity
In this paper we address important issues surrounding the choice of variables
when performing a dynamical systems analysis of alternative theories of
gravity. We discuss the advantages and disadvantages of compactifying the state
space, and illustrate this using two examples. We first show how to define a
compact state space for the class of LRS Bianchi type I models in -gravity
and compare to a non--compact expansion--normalised approach. In the second
example we consider the flat Friedmann matter subspace of the previous example,
and compare the compact analysis to studies where non-compact
non--expansion--normalised variables were used. In both examples we comment on
the existence of bouncing or recollapsing orbits as well as the existence of
static models.Comment: 18 pages, revised to match published versio
Cosmological dynamics of R^n gravity
A detailed analysis of dynamics of cosmological models based on
gravity is presented. We show that the cosmological equations can be written as
a first order autonomous system and analyzed using the standard techniques of
dynamical system theory. In absence of perfect fluid matter, we find exact
solutions whose behavior and stability are analyzed in terms of the values of
the parameter . When matter is introduced, the nature of the (non-minimal)
coupling between matter and higher order gravity induces restrictions on the
allowed values of . Selecting such intervals of values and following the
same procedure used in the vacuum case, we present exact solutions and analyze
their stability for a generic value of the parameter . From this analysis
emerges the result that for a large set of initial conditions an accelerated
expansion is an attractor for the evolution of the cosmology. When matter
is present a transient almost-Friedman phase can also be present before the
transition to an accelerated expansion.Comment: revised and extended version, 35 pages, 12 tables, 14 figures which
are not included and can be found at http://www.mth.uct.ac.za/~peter/R
Theoretical Uncertainties in Electroweak Boson Production Cross Sections at 7, 10, and 14 TeV at the LHC
We present an updated study of the systematic errors in the measurements of
the electroweak boson cross-sections at the LHC for various experimental cuts
for a center of mass energy of 7, 10 and 14 TeV. The size of both electroweak
and NNLO QCD contributions are estimated, together with the systematic error
from the parton distributions. The effects of new versions of the MSTW, CTEQ,
and NNPDF PDFs are considered.Comment: PDFLatex with JHEP3.cls. 22 pages, 43 figures. Version 2 adds the
CT10W PDF set to analysis and updates the final systematic error table and
conclusions, plus several citations and minor wording changes. Version 3 adds
some references on electroweak and mixed QED/QCD corrections. Version 4 adds
more references and acknowledgement
Self-sensing composite material based on piezoelectric nanofibers
Recently, efforts have been made to manufacture self-sensing smart composites by integrating piezoelectric sensors with laminates. However, the interleaving of pressure sensors, such as piezoelectric polymeric films, dramatically reduces the impact resistance of the hosting laminates, and consequently, delamination can occur. This study aimed to fabricate a self-sensing composite material by embedding piezoelectric nanofibers of poly(vinylidenefluoride-trifluoroethylene) (PVDF-TrFE) in a polymeric elastic matrix and carbon black-based electrodes to detect a piezoelectric signal. The mechanical and electrical properties of the self-sensing laminate were maintained after 106 fatigue test cycles. By appropriately tuning the parameters of the acquisition circuit, the sensor could measure not only impulsive loads but also low-frequency loads as low as 0.5 Hz. A piezoelectric model with lumped parameters for the polarization process and piezoelectric response of the nanofibers is proposed and validated by experimental results. As a proof of the model, the piezoelectric nanofiber sensors were embedded in a prosthetic carbon fiber sole, and the piezoelectric signal response closely followed the ground reaction force with a sensitivity of 0.14 mV/N
Cytokine expression patterns in hospitalized children with Bordetella pertussis, Rhinovirus or co-infection
Mechanisms of interaction between Bordetella pertussis and other viral agents are yet to be fully explored. We studied the inflammatory cytokine expression patterns among children with both viral-bacterial infections. Nasopharyngeal aspirate (NPA) samples were taken from children, aged < 1 year, positive for Rhinovirus, Bordetella pertussis and for Rhinovirus and Bordetella pertussis. Forty cytokines were evaluated in NPA by using human cytokine protein arrays and a quantitative analysis was performed on significantly altered cytokines. Forty cytokines were evaluated in NPA by using human cytokine protein arrays and a quantitative analysis was performed on significantly altered cytokines. Our results show that co-infections display a different inflammatory pattern compared to single infections, suggesting that a chronic inflammation caused by one of the two pathogens could be the trigger for exacerbation in co-infections
- …