Sökresultat

Filtyp

Din sökning på "*" gav 531327 sökträffar

Complimentary action : C1q increases ganglion cell survival in an in vitro model of retinal degeneration

Using a previously described retinal explant culture system as an acute injury model, we here explore the role of C1q, the initiator of the classical complement pathway, in neuronal cell survival and retinal homeostasis. Full-thickness adult rat retinal explants were divided into four groups, receiving the following supplementation: C1q (50 nM), C1-inhibitor (C1-inh; Berinert; 500 mg/l), C1q + C1-

Closed-loop Prevention of Hypotension in the Heartbeating Brain-dead Porcine Model

Objective: The purpose of this paper is to demonstrate feasibility of a novel closed-loop controlled therapy for prevention of hypertension in the heartbeating brain-dead porcine model. Methods: Dynamic modeling and system identification were based on in-vivo data. A robust controller design was obtained for the identified models. Disturbance attenuation properties, and reliability of operation of

An automatic tuner with short experiment and probabilistic plant parameterization

A novel automatic tuning strategy is proposed. It is based on an experiment of very short duration, followed by simultaneous identification of LTI model parameters and an estimate of their error covariance. The parametric uncertainty model is subsequently exploited to design linear controllers with magnitude bounds on some closed-loop transfer function of interest, such as the sensitivity function

Autotuning of an In-Line pH Control System

A novel autotuning procedure is presented through application to an industrial in-line pH control system. The procedure has three advantages over classical relay auto-tuners: experiment duration is very short (no need for limit-cycle convergence); all data is used for identification (instead of only peaks and switch instances); a parameter uncertainty model is identified and utilized for robust co

Hard hadronic diffraction is not hard

Hadronic diffractive processes characterized by a hard scale (hard diffraction) contain a nontrivial interplay of hard and soft, nonperturbative interactions, which breaks down factorization of short and long distances. On the contrary to the expectations based on the factorization hypothesis, assuming that hard diffraction is a higher twist, these processes should be classified as a leading twist

Composite scalar dark matter from vector-like SU (2) confinement

A toy-model with SU(2)TC dynamics confined at high scales ΛTC > 100GeV enables to construct Dirac UV completion from the original chiral multiplets predicting a vector-like nature of their weak interactions consistent with electroweak precision tests. In this work, we investigate a potential of the lightest scalar baryon-like (T-baryon) state B0 = UD with mass mB ≥ 1TeV predicted by the simplest t

Can the diphoton enhancement at 750 GeV be due to a neutral technipion?

We discuss a scenario in which the diphoton enhancement at Mγγ=750 GeV, observed by the ATLAS and CMS collaborations, is a neutral technipion π0. We consider two distinct minimal models for the dynamical electroweak symmetry breaking. In a first one, two-flavor vectorlike technicolor (VTC) model, we assume that the two-photon fusion is a dominant production mechanism. We include γγ→π0 and producti

Nuclear effects in Drell-Yan pair production in high-energy pA collisions

The Drell-Yan (DY) process of dilepton pair production off nuclei is not affected by final state interactions, energy loss, or absorption. A detailed phenomenological study of this process is thus convenient for investigation of the onset of initial-state effects in proton-nucleus (pA) collisions. In this paper, we present a comprehensive analysis of the DY process in pA interactions at RHIC and L

Systematic study of real photon and Drell-Yan pair production in p+A (d+A) interactions

We study nuclear effects in production of Drell-Yan pairs and direct photons in proton-nucleus collisions. For the first time, these effects are studied within the color dipole approach using the Green function formalism which naturally incorporates the color transparency and quantum coherence effects. The corresponding numerical results for the nuclear modification factor are compared with availa

Nuclear effects in Drell-Yan production at the LHC

Using the color dipole formalism we study production of Drell-Yan (DY) pairs in proton-nucleus interactions in the kinematic region corresponding to LHC experiments. Lepton pairs produced in a hard scattering are not accompanied with any final state interactions leading to either energy loss or absorption. Consequently, dileptons may serve as more efficient and cleaner probes for the onset of nucl

Dynamic color screening in diffractive deep inelastic scattering

We present a novel Monte Carlo implementation of dynamic color screening via multiple exchanges of semisoft gluons as a basic QCD mechanism to understand diffractive electron-proton scattering at the HERA collider. Based on the kinematics of individual events in the standard QCD description of deep inelastic scattering at the parton level, which at low x is dominantly gluon initiated, the probabil

The Drell-Yan process as a testing ground for parton distributions up to LHC

The Drell-Yan massive dilepton production in hadron-hadron collisions provides a unique tool, complementary to Deep Inelastic Scattering, for improving our understanding of hadronic substructure and in particular for testing parton distributions. We will consider measurements of the differential and double-differential Drell-Yan cross sections from FNAL Tevatron up to CERN LHC energies and they wi

Diffractive W production in SCI models

The soft color interaction model (SCI) as an add-on to standard perturbative QCD describes diffractive processes by allowing for additional soft color-octet exchanges below the conventional threshold for parton showering. We discuss how diffractive and inclusive event samples for diffractive hard processes can be obtained from a Monte Carlo in a unified way for pp → p[W± +X]p as an example, and di

Tour-loop QCD analysis of the Bjorken sum rule

We study the polarized Bjorken sum rule (BSR) at low momentum transfers in the range 0.223LO expression for the coefficient function CBj(αs) in the framework of the common QCD perturbation theory (PT) and the singularity-free analytic perturbation theory (APT). The analysis of the PT series for CBj(αs) gives a hint to its asymptotic nature manifesting itself in the region Q

Diffractive pQCD mechanism of exclusive production of W+W - pairs in proton-proton collisions

We present a study of central exclusive production of W+W - pairs in proton-proton collisions at the LHC. We compare the contribution of the γγ → W+W- mechanism with a new mechanism of exclusive diffractive production through the gg → W+W- subprocess with intermediate virtual Higgs boson and quark box diagrams. The amplitude for the latter process is expressed in terms of the off-diagonal unintegr

QCD factorisation breaking in diffractive gauge bosons production at the LHC

We discuss single diffractive gauge bosons (γ*, W±, Z) production in proton-proton collisions at LHC energy (14 TeV) in the framework of the color dipole approach. The calculations are performed for gauge bosons produced at forward rapidities. The diffractive cross section is predicted as a function of fractional momentum and invariant mass of the lepton pair. We found a dramatic breakdown of the

Central exclusive quark-antiquark dijet and standard model Higgs boson production in proton-(anti)proton collisions

We consider the central exclusive production of qq̄ pairs and Higgs boson in proton-proton collisions at LHC. The amplitude for the process is derived within the k -factorization approach and considered in different kinematical asymptotics, in particular, in the important high quark transverse momenta and massless quark limits. Quark helicity and spin-projection amplitudes in two different frames

Diffractive deep inelastic scattering from multiple soft gluon exchange in QCD

Diffractive hard scattering is interpreted as the effect of soft gluon exchanges between the emerging energetic quarks and the nucleon's color field, resulting in an overall color singlet exchange. Summing multiple gluon exchanges to all orders leads to exponentiation and an amplitude in analytic form. Numerical evaluation reproduces the precise HERA data and gives new insights on the density of g

Top-pair production and decay at the LC

Top quark pairs production and decay are considered in the framework of the smeared-mass unstable particles model. The results are in good agreement with the previous ones in the literature. Suggested approach significantly simplifies calculations compared to the standard perturbative one.