172 research outputs found
Shock wave collisions in AdS5: approximate numerical solutions
We numerically study the evolution of a boost-invariant N=4 SYM medium using
AdS/CFT. We consider a toy model for the collision of gravitational shock
waves, finding that the energy density first increases, reaches a maximum and
then starts to decrease, matching hydrodynamics for late times. For the initial
conditions we consider, the hydrodynamic scale governing the late time
behaviour is to very good approximation determined by the area of the black
hole horizon at initial times. Our results provide a toy model for the early
time evolution of the bulk system in heavy-ion collisions at RHIC and the LHC.Comment: 29 pages, 9 figure
Fouling and Cleaning of Modified Stainless Steel Plate Heat Exchangers Processing Milk Products
Fouling of heat exchangers in dairy industries is still quite a severe problem both technically and economically. Altering the surface properties of the heating surfaces would be a way of solving this issue.
Modified steel surfaces were tested in an Alfa Laval V2 plate heat exchanger throughout dairy product sterilization. The behavior was analyzed for 8 different surface treatments, such as coatings (Diamond Like Carbon [DLC], Silica, SiOX, Ni-P-PTFE, ExcaliburÂź, XylanÂź) and ion implantation (SiF+, MoS2).
All fouling and cleaning experiments were carried out in standard and well-controlled operating conditions. After fouling, no significant difference could be seen between all the modified steels and the reference by statistical variance analysis. Cleaning efficiency of Ni-PPTFE appeared significantly the best. It could be suggested that the free surface energy plays a predominant role and the roughness a minor role in the level of fouling and cleaning efficiency
The dynamics of quark-gluon plasma and AdS/CFT
In these pedagogical lectures, we present the techniques of the AdS/CFT
correspondence which can be applied to the study of real time dynamics of a
strongly coupled plasma system. These methods are based on solving
gravitational Einstein's equations on the string/gravity side of the AdS/CFT
correspondence. We illustrate these techniques with applications to the
boost-invariant expansion of a plasma system. We emphasize the common
underlying AdS/CFT description both in the large proper time regime where
hydrodynamic dynamics dominates, and in the small proper time regime where the
dynamics is far from equilibrium. These AdS/CFT methods provide a fascinating
arena interrelating General Relativity phenomenae with strongly coupled gauge
theory physics.Comment: 35 pages, 3 figures. Lectures at the 5th Aegean summer school, `From
gravity to thermal gauge theories: the AdS/CFT correspondence'. To appear in
the proceedings in `Lecture Notes in Physics
Long-Range Rapidity Correlations in Heavy Ion Collisions at Strong Coupling from AdS/CFT
We use AdS/CFT correspondence to study two-particle correlations in heavy ion
collisions at strong coupling. Modeling the colliding heavy ions by shock waves
on the gravity side, we observe that at early times after the collision there
are long-range rapidity correlations present in the two-point functions for the
glueball and the energy-momentum tensor operators. We estimate rapidity
correlations at later times by assuming that the evolution of the system is
governed by ideal Bjorken hydrodynamics, and find that glueball correlations in
this state are suppressed at large rapidity intervals, suggesting that
late-time medium dynamics can not "wash out" the long-range rapidity
correlations that were formed at early times. These results may provide an
insight on the nature of the "ridge" correlations observed in heavy ion
collision experiments at RHIC and LHC, and in proton-proton collisions at LHC.Comment: 32 pages, 2 figures; v2: typos corrected, references adde
Deep Inelastic Scattering in Conformal QCD
We consider the Regge limit of a CFT correlation function of two vector and
two scalar operators, as appropriate to study small-x deep inelastic scattering
in N=4 SYM or in QCD assuming approximate conformal symmetry. After clarifying
the nature of the Regge limit for a CFT correlator, we use its conformal
partial wave expansion to obtain an impact parameter representation encoding
the exchange of a spin j Reggeon for any value of the coupling constant. The
CFT impact parameter space is the three-dimensional hyperbolic space H3, which
is the impact parameter space for high energy scattering in the dual AdS space.
We determine the small-x structure functions associated to the exchange of a
Reggeon. We discuss unitarization from the point of view of scattering in AdS
and comment on the validity of the eikonal approximation.
We then focus on the weak coupling limit of the theory where the amplitude is
dominated by the exchange of the BFKL pomeron. Conformal invariance fixes the
form of the vector impact factor and its decomposition in transverse spin 0 and
spin 2 components. Our formalism reproduces exactly the general results predict
by the Regge theory, both for a scalar target and for gamma*-gamma* scattering.
We compute current impact factors for the specific examples of N=4 SYM and QCD,
obtaining very simple results. In the case of the R-current of N=4 SYM, we show
that the transverse spin 2 component vanishes. We conjecture that the impact
factors of all chiral primary operators of N=4 SYM only have components with 0
transverse spin.Comment: 44+16 pages, 7 figures. Some correction
Morphological assessment of non-human primate models of osteoarthritis: Comparisons of HR-MRI with CT arthrography (CTA)
International audienc
Quantum Fluctuations and the Unruh Effect in Strongly-Coupled Conformal Field Theories
Through the AdS/CFT correspondence, we study a uniformly accelerated quark in
the vacuum of strongly-coupled conformal field theories in various dimensions,
and determine the resulting stochastic fluctuations of the quark trajectory.
From the perspective of an inertial observer, these are quantum fluctuations
induced by the gluonic radiation emitted by the accelerated quark. From the
point of view of the quark itself, they originate from the thermal medium
predicted by the Unruh effect. We scrutinize the relation between these two
descriptions in the gravity side of the correspondence, and show in particular
that upon transforming the conformal field theory from Rindler space to the
open Einstein universe, the acceleration horizon disappears from the boundary
theory but is preserved in the bulk. This transformation allows us to directly
connect our calculation of radiation-induced fluctuations in vacuum with the
analysis by de Boer et al. of the Brownian motion of a quark that is on average
static within a thermal medium. Combining this same bulk transformation with
previous results of Emparan, we are also able to compute the stress-energy
tensor of the Unruh thermal medium.Comment: 1+31 pages; v2: reference adde
Early-Time Energy Loss in a Strongly-Coupled SYM Plasma
We carry out an analytic study of the early-time motion of a quark in a
strongly-coupled maximally-supersymmetric Yang-Mills plasma, using the AdS/CFT
correspondence. Our approach extracts the first thermal effects as a small
perturbation of the known quark dynamics in vacuum, using a double expansion
that is valid for early times and for (moderately) ultrarelativistic quark
velocities. The quark is found to lose energy at a rate that differs
significantly from the previously derived stationary/late-time result: it
scales like T^4 instead of T^2, and is associated with a friction coefficient
that is not independent of the quark momentum. Under conditions representative
of the quark-gluon plasma as obtained at RHIC, the early energy loss rate is a
few times smaller than its late-time counterpart. Our analysis additionally
leads to thermally-corrected expressions for the intrinsic energy and momentum
of the quark, in which the previously discovered limiting velocity of the quark
is found to appear naturally.Comment: 39 pages, no figures. v2: Minor corrections and clarifications.
References added. Version to be published in JHE
Caplacizumab reduces the frequency of major thromboembolic events, exacerbations, and death in patients with acquired thrombotic thrombocytopenic purpura.
BACKGROUND
Acquired thrombotic thrombocytopenic purpura (aTTP) is a life-threatening autoimmune thrombotic microangiopathy. In spite of treatment with plasma exchange and immunosuppression, patients remain at risk for thrombotic complications, exacerbations and death. In the Phase II TITAN study, treatment with caplacizumab, an anti-vWF Nanobody(Âź) , was shown to reduce the time to confirmed platelet count normalization and exacerbations during treatment.
OBJECTIVE
The clinical benefit of caplacizumab was further investigated in a post-hoc analysis of the incidence of major thromboembolic events and exacerbations during the study drug treatment period and TTP-related death during the study.
METHODS
The Standardized MedDRA Query (SMQ) for 'embolic and thrombotic events' was run to investigate the occurrence of major thromboembolic events and exacerbations in the safety population of the TITAN study, which consisted of 72 patients of whom 35 received caplacizumab and 37 received placebo.
RESULTS
Four events (1 pulmonary embolism and 3 aTTP exacerbations) were reported in 4 patients in the caplacizumab group, while 20 such events were reported in 14 patients in the placebo group (2 acute myocardial infarctions, 1 ischemic and 1 hemorrhagic stroke, 1 pulmonary embolism, 1 deep vein thrombosis, 1 venous thrombosis and 13 aTTP exacerbations). Two of the placebo-treated patients died from aTTP during the study.
CONCLUSION
In total, 11.4% of caplacizumab-treated patients versus 43.2% of placebo-treated patients experienced one or more major thromboembolic event, an exacerbation or died. This analysis shows the potential for caplacizumab to reduce the risk of major thromboembolic morbidities and mortality associated with aTTP. This article is protected by copyright. All rights reserved
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