1,363 research outputs found
Parton Density Uncertainties and the Determination of Electroweak Parameters at Hadron Colliders
We discuss the determination of electroweak parameters from hadron collider
observables, focusing on the boson mass measurement. We revise the
procedures adopted in the literature to include in the experimental analysis
the uncertainty due to our imperfect knowledge of the proton structure. We show
how the treatment of the proton parton density functions (PDFs) uncertainty as
a source of systematic error, leads to the automatic inclusion in the fit of
the bin-bin correlation of the kinematic distributions with respect to PDF
variations. In the case of the determination of from the charged lepton
transverse momentum distribution, we observe that the inclusion of this
correlation factor yields a strong reduction of the PDF uncertainty, given a
sufficiently good control over all the other error sources. This improvement
depends on a systematic accounting of the features of the QCD-based PDF model,
and it is achieved relying only on the information available in current PDF
sets. While a realistic quantitative estimate requires to take into account the
details of the experimental systematics, we argue that, in perspective, the
proton PDF uncertainty will not be a bottleneck for precision measurements.Comment: 5 pages, 6 figures; v2: title changed, minor textual changes, version
published on PR
Towards precise predictions for Higgs-boson production in the MSSM
We study the production of scalar and pseudoscalar Higgs bosons via gluon
fusion and bottom-quark annihilation in the MSSM. Relying on the NNLO-QCD
calculation implemented in the public code SusHi, we provide precise
predictions for the Higgs-production cross section in six benchmark scenarios
compatible with the LHC searches. We also provide a detailed discussion of the
sources of theoretical uncertainty in our calculation. We examine the
dependence of the cross section on the renormalization and factorization
scales, on the precise definition of the Higgs-bottom coupling and on the
choice of PDFs, as well as the uncertainties associated to our incomplete
knowledge of the SUSY contributions through NNLO. In particular, a potentially
large uncertainty originates from uncomputed higher-order QCD corrections to
the bottom-quark contributions to gluon fusion.Comment: 62 pages, 24 pdf figures; v2: minor clarifications, improved plot
quality, matches published versio
Dynamics of Nucleation in the Ising Model
Reactive pathways to nucleation in a three-dimensional Ising model at 60% of
the critical temperature are studied using transition path sampling of single
spin flip Monte Carlo dynamics. Analysis of the transition state ensemble (TSE)
indicates that the critical nuclei are rough and anisotropic. The TSE,
projected onto the free energy surface characterized by cluster size, N, and
surface area, S, indicates the significance of other variables in addition to
these two traditional reaction coordinates for nucleation. The transmission
coefficient along N is ~ 0.35, and this reduction of the transmission
coefficient from unity is explained in terms of the stochastic nature of the
dynamic model.Comment: In press at the Journal of Physical Chemistry B, 7 pages, 8 figure
Vacuum Condensates and Dynamical Mass Generation in Euclidean Yang-Mills Theories
Vacuum condensates of dimension two and their relevance for the dynamical
mass generation for gluons in Yang-Mills theories are discussedComment: Talk given at the International Conference on Color Confinement and
Hadrons in Quantum Chromodynamics, Confinement 2003, TITech and RIKEN, Tokyo,
Japan, July 21-24, 200
Noncommutative Electrodynamics
In this paper we define a causal Lorentz covariant noncommutative (NC)
classical Electrodynamics. We obtain an explicit realization of the NC theory
by solving perturbatively the Seiberg-Witten map. The action is polynomial in
the field strenght , allowing to preserve both causality and Lorentz
covariance. The general structure of the Lagrangian is studied, to all orders
in the perturbative expansion in the NC parameter . We show that
monochromatic plane waves are solutions of the equations of motion to all
orders. An iterative method has been developed to solve the equations of motion
and has been applied to the study of the corrections to the superposition law
and to the Coulomb law.Comment: 13 pages, 2 figures, one reference adde
Efficacy of SSRIs on cognition of Alzheimer's disease patients treated with cholinesterase inhibitors.
Background: This study examines the joint effect on cognition of selective serotonin re-uptake inhibitors
(SSRIs) and cholinesterase inhibitors (AChEIs) in depressed patients affected by Alzheimerâs disease (AD)
living at home.
Methods: The study was conducted in two different outpatient neurological clinics. 338 patients with probable
ADwere treated with ChEis (donepezil, rivastigmine and galantamine) as per the clinicianâs judgment and were
observed for nine months. At study entry, participants underwent a multidimensional assessment evaluating
cognitive, functional and psychobehavioral domains. All patients were evaluated at baseline, after one (T1),
three (T2) and nine months (T3). Patients were grouped in three different categories (patients not depressed
and not treated with SSRIs, patients depressed and treated with SSRIs, and patients depressed but not treated
with SSRIs).
Results: At baseline 182 were diagnosed as not depressed and not treated with SSRIs, 66 as depressed and
treated with SSRIs, and 90 as depressed but not treated with SSRIs. The mean change in MMSE score
from baseline to nine months showed that depressed patients not treated worsened in comparison with those
not depressed and not treated with SSRIs (mean change â0.8±2.3 vs 0.04±2.9; p = 0.02) and patients
depressed and treated with SSRI (mean change â0.8±2.3 vs 0.1±2.5; p = 0.03).
Conclusions: In AD patients treated with AChEIs, SSRIs may exert some degree of protection against the
negative effects of depression on cognition
COVID-19 : The European institute of oncology as a "hub" centre for breast cancer surgery during the pandemic in Milan (Lombardy region, northern Italy) - A screenshot of the first month
Risk factors for obstructive sleep apnea syndrome in children: state of the art
The obstructive sleep apnea syndrome (OSAS) represents only part of a large group of pathologies of variable entity called respiratory sleep disorders (RSD) which include simple snoring and increased upper airway resistance syndrome (UARS). Although the etiopathogenesis of adult OSAS is well known, many aspects of this syndrome in children are still debated. Its prevalence is about 2% in children from 2 to 8 years of age, mostly related to the size of the upper airways adenoid tissue. Several risk factors linked to the development of OSAS are typical of the pediatric age. The object of this paper is to analyze the state of the art on this specific topic, discussing its implications in terms of diagnosis and management
NaNet: a Low-Latency, Real-Time, Multi-Standard Network Interface Card with GPUDirect Features
While the GPGPU paradigm is widely recognized as an effective approach to
high performance computing, its adoption in low-latency, real-time systems is
still in its early stages.
Although GPUs typically show deterministic behaviour in terms of latency in
executing computational kernels as soon as data is available in their internal
memories, assessment of real-time features of a standard GPGPU system needs
careful characterization of all subsystems along data stream path.
The networking subsystem results in being the most critical one in terms of
absolute value and fluctuations of its response latency.
Our envisioned solution to this issue is NaNet, a FPGA-based PCIe Network
Interface Card (NIC) design featuring a configurable and extensible set of
network channels with direct access through GPUDirect to NVIDIA Fermi/Kepler
GPU memories.
NaNet design currently supports both standard - GbE (1000BASE-T) and 10GbE
(10Base-R) - and custom - 34~Gbps APElink and 2.5~Gbps deterministic latency
KM3link - channels, but its modularity allows for a straightforward inclusion
of other link technologies.
To avoid host OS intervention on data stream and remove a possible source of
jitter, the design includes a network/transport layer offload module with
cycle-accurate, upper-bound latency, supporting UDP, KM3link Time Division
Multiplexing and APElink protocols.
After NaNet architecture description and its latency/bandwidth
characterization for all supported links, two real world use cases will be
presented: the GPU-based low level trigger for the RICH detector in the NA62
experiment at CERN and the on-/off-shore data link for KM3 underwater neutrino
telescope
Penile prosthesis implant for erectile dysfunction: A new minimally invasive infrapubic surgical technique
Erectile dysfunction, the most common
male sexual disorder after premature ejaculation,
with its important impact on man and partnerâs sexuality
and quality of life is a persistent inability to obtain and
maintain an erection sufficient to permit satisfactory sexual
performance. Non-surgical treatments with controversial
results are usually applyed before surgical treatment that has
reached high levels of satisfaction.
We describe a new surgical technique to implant three-pieces
penile prosthesis in patients suffering from erectile dysfunction
(ED) not responding to conventional medical therapy or
reporting side effects with such a therapy.
Implantation of an inflatable prosthesis, for treatment of ED,
is a safe and efficacious approach with high satisfaction
reported by patients and partners. Surgical technique should
be minimally invasive and latest technology equipment should
be implanted in order to decrease common complications and
to obtain a better aesthetic result
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