14,105 research outputs found
QCD Collisional Energy Loss in an Increasingly Interacting Quark Gluon Plasma
The discovery of the jet quenching in central Au + Au collisions at the
Relativistic Heavy-ion Collider (RHIC) at Brookhaven National Laboratory has
provided clear evidence for the formation of strongly interacting dense matter.
It has been predicted to occur due to the energy loss of high energy partons
that propagate through the quark gluon plasma. In this paper we investigate the
dependence of the parton energy loss due to elastic scatterings in a parton
plasma on the value of the strong coupling and its running with the evolution
of the system. We analyze different prescriptions for the QCD coupling and
calculate the energy and length dependence of the fractional energy loss.
Moreover, the partonic quenching factor for light and heavy quarks is
estimated. We found that the predicted enhancement of the heavy to light
hadrons () ratio is strongly dependent on the running of the QCD
coupling constant.Comment: 16 pages, 8 figures. Version to be published in the International
Journal of Modern Physics
On duality relations for session types
Session types are a type formalism used to describe communication protocols over private session channels. Each participant in a binary session owns one endpoint of a session channel. A key notion is that of duality: the endpoints of a session channel should have dual session types in order to guarantee communication safety. Duality relations have been independently defined in different ways and different works, without considering their effect on the type system. In this paper we systematically study the existing duality relations and some new ones, and compare them in order to understand their expressiveness. The outcome is that those relations are split into two groups, one related to the na¨ıve inductive duality, and the other related to a notion of mutual compliance, which we borrow from the literature on contracts for web-services
Molekulare Signalwege der aseptischen Endoprothesenlockerung (Molecular pathways in aseptic loosening of orthopaedic endoprosthesis)
Abstract Operative joint replacement to treat disabling joint conditions secondary to degenerative and inflammatory arthritides has become one of the most efficacious and cost-effective procedures to relieve pain and restore joint function. However, prosthetic implants are not built to last forever and osteolysis and aseptic loosening has been associated with prosthetic arthroplasties since their introduction. The functional life of a synthetic joint is influenced by many factors including the material of the implant, operation procedures and the surgeon involved, as well as patient-related factors. Although promising developments have been achieved in this field, more than 10% of all implants still have to undergo operative revision within 15 years after the initial operation. Failure due to sepsis, fractures and dislocations has become rare; premature loosening of implants on the other hand is becoming much more important. Prosthetic loosening without concurrent infection or trauma is called aseptic loosening. It is generally accepted that small particles ("wear debris") and activated macrophages play a key role in aseptic loosening. The pathophysiology of this condition, however, is still not very well characterized. In this article, we review the molecular mechanisms and signal pathways that were unravelled as responsible factors for loosening orthopaedic implants. Finally, we discuss possible novel strategies for future therapeutic approaches
Estimations for the Single Diffractive production of the Higgs boson at the Tevatron and the LHC
The single diffractive production of the standard model Higgs boson is
computed using the diffractive factorization formalism, taking into account a
parametrization for the Pomeron structure function provided by the H1
Collaboration. We compute the cross sections at next-to-leading order accuracy
for the gluon fusion process, which includes QCD and electroweak corrections.
The gap survival probability () is also introduced to account for
the rescattering corrections due to spectator particles present in the
interaction, and to this end we compare two different models for the survival
factor. The diffractive ratios are predicted for proton-proton collisions at
the Tevatron and the LHC for the Higgs boson mass of = 120 GeV.
Therefore, our results provide updated estimations for the diffractive ratios
of the single diffractive production of the Higgs boson in the Tevatron and LHC
kinematical regimes.Comment: 20 pages, 6 figures, 3 table
Application of Computer Vision for quality control in frozen mixed berries production: colour calibration issues
Computer vision is becoming increasingly important in quality control of many food processes. The appearance properties of food products (colour, texture, shape and size) are, in fact, correlated with organoleptic characteristics and/or the presence of defects. Quality control based on image processing eliminates the subjectivity of human visual inspection, allowing rapid and non-destructive analysis. However, most food matrices show a wide variability in appearance features, therefore robust and customized image elaboration algorithms have to be implemented for each specific product. For this reason, quality control by visual inspection is still rather diffused in several food processes. The case study inspiring this paper concerns the production of frozen mixed berries. Once frozen, different kinds of berries are mixed together, in different amounts, according to a recipe. The correct quantity of each kind of fruit, within a certain tolerance, has to be ensured by producers. Quality control relies on bringing few samples for each production lot (samples of the same weight) and, manually, counting the amount of each species. This operation is tedious, subject to errors, and time consuming, while a computer vision system (CVS) could determine the amount of each kind of berries in a few seconds. This paper discusses the problem of colour calibration of the CVS used for frozen berries mixture evaluation. Images are acquired by a digital camera coupled with a dome lighting system, which gives a homogeneous illumination on the entire visible surface of the berries, and a flat bed scanner. RBG device dependent data are then mapped onto CIELab colorimetric colour space using different transformation operators. The obtained results show that the proposed calibration procedure leads to colour discrepancies comparable or even below the human eyes sensibility
Un-reduction
This paper provides a full geometric development of a new technique called
un-reduction, for dealing with dynamics and optimal control problems posed on
spaces that are unwieldy for numerical implementation. The technique, which was
originally concieved for an application to image dynamics, uses Lagrangian
reduction by symmetry in reverse. A deeper understanding of un-reduction leads
to new developments in image matching which serve to illustrate the
mathematical power of the technique.Comment: 25 pages, revised versio
A propòsit de les suposades pintures i gravats prehistòrics de la cova d'en Dayna (Romanyà de la Selva. Baix Empordà )
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