4,933 research outputs found
Parton Distributions for Event Generators
In this paper, conventional Global QCD analysis is generalized to produce
parton distributions optimized for use with event generators at the LHC. This
optimization is accomplished by combining the constraints due to existing
hard-scattering experimental data with those from anticipated cross sections
for key representative SM processes at LHC (by the best available theory) as
joint input to the global analyses. The PDFs obtained in these new type of
global analyses using matrix elements calculated in any given order will be
best suited to work with event generators of that order, for predictions at the
LHC. This is most useful for LO event generators at present. Results obtained
from a few candidate PDF sets (labeled as CT09MCS, CT09MC1 and CT09MC2) for LO
event generators produced in this way are compared with those from other
approaches.Comment: 35 pages, 19 figures, and 4 table
MINLO: Multi-scale improved NLO
In the present work we consider the assignment of the factorization and
renormalization scales in hadron collider processes with associated jet
production, at next-to-leading order (NLO) in perturbation theory. We propose a
simple, definite prescription to this end, including Sudakov form factors to
consistently account for the distinct kinematic scales occuring in such
collisions. The scheme yields results that are accurate at NLO and, for a large
class of observables, it resums to all orders the large logarithms that arise
from kinematic configurations involving disparate scales. In practical terms
the method is most simply understood as an NLO extension of the matrix element
reweighting procedure employed in tree level matrix element-parton shower
merging algorithms. By way of a proof-of-concept, we apply the method to Higgs
and Z boson production in association with up to two jets.Comment: 27 pages, 17 figure
Meaning behind measurement : self-comparisons affect responses to health related quality of life questionnaires
Purpose The subjective nature of quality of life is particularly pertinent to the domain of health-related quality of
life (HRQOL) research. The extent to which participants’ responses are affected by subjective information and personal reference frames is unknown. This study investigated how an elderly population living with a chronic metabolic bone disorder evaluated self-reported quality of life. Methods Participants (n = 1,331) in a multi-centre randomised controlled trial for the treatment of Paget’s disease completed annual HRQOL questionnaires, including the SF-36, EQ-5D and HAQ. Supplementary questions were added to reveal implicit reference frames used when making HRQOL evaluations. Twenty-one participants (11 male, 10 female, aged 59–91 years) were interviewed retrospectively about their responses to the supplementary questions, using cognitive interviewing techniques and semi-structured topic guides. Results The interviews revealed that participants used complex and interconnected reference frames to promote response shift when making quality of life evaluations. The choice of reference frame often reflected external factors unrelated to individual health. Many participants also stated that they were unclear whether to report general or disease-related HRQOL. Conclusions It is important, especially in clinical trials, to provide instructions clarifying whether ‘quality of life’ refers to disease-related HRQOL. Information on selfcomparison reference frames is necessary for the interpretation of responses to questions about HRQOL.The Chief Scientist Office of the Scottish Government Health Directorates,
The PRISM funding bodies (the Arthritis Research Campaign, the National Association for the Relief of Paget’s disease and the Alliance for Better Bone Health)Peer reviewedAuthor final versio
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The measurement of serum paracetamol using a discrete analyser.
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Approximation for Cooperative Interactions of a Spatially-Detailed Cardiac Sarcomere Model
We developed a novel ordinary differential equation (ODE) model, which produced results that correlated well with the Monte Carlo (MC) simulation when applied to a spatially-detailed model of the cardiac sarcomere. Configuration of the novel ODE model was based on the Ising model of myofilaments, with the “co-operative activation” effect introduced to incorporate nearest-neighbor interactions. First, a set of parameters was estimated using arbitrary Ca transient data to reproduce the combinational probability for the states of three consecutive regulatory units, using single unit probabilities for central and neighboring units in the MC simulation. The parameter set thus obtained enabled the calculation of the state transition of each unit using the ODE model with reference to the neighboring states. The present ODE model not only provided good agreement with the MC simulation results but was also capable of reproducing a wide range of experimental results under both steady-state and dynamic conditions including shortening twitch. The simulation results suggested that the nearest-neighbor interaction is a reasonable approximation of the cooperativity based on end-to-end interactions. Utilizing the modified ODE model resulted in a reduction in computational costs but maintained spatial integrity and co-operative effects, making it a powerful tool in cardiac modeling
Altered SMRT levels disrupt vitamin D3 receptor signalling in prostate cancer cells.
We hypothesized that key antiproliferative target genes for the vitamin D receptor (VDR) were repressed by an epigenetic mechanism in prostate cancer cells resulting in apparent hormonal insensitivity. To explore this possibility, we examined nuclear receptor corepressor expression in a panel of nonmalignant and malignant cell lines and primary cultures, and found frequently elevated SMRT corepressor mRNA expression often associated with reduced sensitivity to 1alpha,25-dihydroxyvitamin D(3) (1alpha,25(OH)2D3). For example, PC-3 and DU-145 prostate cancer cell lines had 1.8-fold and twofold increases in SMRT mRNA relative to normal PrEC cells (P<0.05). Similarly, 10/15 primary tumour cultures (including three matched to normal cells from the same donors) had elevated SMRT mRNA levels; generally NCoR1 and Alien were not as commonly elevated. Corepressor proteins often have associated histone deacetylases (HDAC) and reflectively the antiproliferative action of 1alpha,25(OH)2D3 can be restored by cotreatment with low doses of HDAC inhibitors such as trichostatin A (TSA, 15 nM) to induce apoptosis in prostate cancer cell lines. To decipher the transcriptional events that lead to these cellular responses, we undertook gene expression studies in PC-3 cells after cotreatment of 1alpha,25(OH)2D3 plus TSA after 6 h. Examination of known VDR target genes and cDNA microarray analyses revealed cotreatment of 1alpha,25(OH)2D3 plus TSA cooperatively upregulated eight (out of 1176) genes, including MAPK-APK2 and GADD45alpha. MRNA and protein time courses and inhibitor studies confirmed these patterns of regulation. Subsequently, we knocked down SMRT levels in PC-3 cells using a small interfering RNA (siRNA) approach and found that GADD45alpha induction by 1alpha,25(OH)2D3 alone became very significantly enhanced. The same distortion of gene responsiveness, with repressed induction of GADD45alpha was found in primary tumour cultures compared and to matched peripheral zone (normal) cultures from the same donor. These data demonstrate that elevated SMRT levels are common in prostate cancer cells, resulting in suppression of target genes associated with antiproliferative action and apparent 1alpha,25(OH)2D3-insensitivity. This can be targeted therapeutically by combination treatments with HDAC inhibitors
Measuring hsCRP—An Important Part of a Comprehensive Risk Profile or a Clinically Redundant Practice?
James McCormack and Michael Allan discuss issues and questions surrounding hsCRP measurements in patients
Vector boson pair production at the LHC
We present phenomenological results for vector boson pair production at the
LHC, obtained using the parton-level next-to-leading order program MCFM. We
include the implementation of a new process in the code, pp -> \gamma\gamma,
and important updates to existing processes. We incorporate fragmentation
contributions in order to allow for the experimental isolation of photons in
\gamma\gamma, W\gamma, and Z\gamma production and also account for gluon-gluon
initial state contributions for all relevant processes. We present results for
a variety of phenomenological scenarios, at the current operating energy of
\sqrt{s} = 7 TeV and for the ultimate machine goal, \sqrt{s} = 14 TeV. We
investigate the impact of our predictions on several important distributions
that enter into searches for new physics at the LHC.Comment: 35 pages, 14 figure
Why do people fail to turn good intentions into action? : The role of executive control processes in the translation of healthy eating intentions into action in young Scottish adults
Non peer reviewedPublisher PD
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