149 research outputs found
Density Matrix Kinetic Equation Describing a Passage of Fast Atomic Systems Through Matter
The quantum-mechanical consideration of a passage of fast dimesoatoms through
matter is given. A set of quantum-kinetic equations for the density matrix
elements describing their internal state evolution is derived. It is shown that
probabilistic description of internal dynamics of hydrogen-like atoms is
impossible even at sufficiently low energies because of the ``accidental''
degeneracy of their energy levels.Comment: 12 pages, LATEX, submitted to J. Phys.
GENE-CELL THERAPY OF HIV AND HEMATOLOGICAL MALIGNANCES BASED ON HEMATOPOIETIC STEM CELL TRANSPLANTATION AND SITE-SPECIFIC GENOME EDITING
Based on the annual UNAIDS reports the number of HIVinfected patients is continually growing since 1983. Antiretroviral Therapy (ART) allows to prolong life expectancy, but the problem of life quality and overall survival is still remaining. Nowadays, in the era of ART, one of the main cause of mortality in HIV-infected patients is malignancies. Lymphomas play one of the key roles in this group of diseases. The treatment of lymphomas includes combined regiments of chemotherapy with a curative potential. High dose chemotherapy with autologous hematopoietic stem cell transplant (auto-HSCT) is the main path of the treatment for relapsed / refractory lymphomas. In the last few years with a development of the genome editing technology auto-HSCT is becoming one of the most promising methods of HIV treatment. The case of “Berlin patient” when allogeneic HSCT from donor with mutation CCR5-delta32 lead to cure from HIV and proof of concept the efficacy of the gene therapy for HIV based on HSCT. Hematopoietic stem cell transplantation with edited autologous HSC (CCR5 knockout by site-specific genome editing tools with engineering nucleases) is a comprehensive treatment for this cohort of patients. On one hand, high dose chemotherapy with auto-HSCT cures the malignancy; on the other hand auto-HSCT works as a delivery method for the edited cells and creates an environment for the HIV eradication. This review is dedicated to HIV and oncology, methods of treatment of hematological malignancies and HIV-infection using genome editing technology based on HSCT
Determination of scattering lengths from measurement of atom lifetime
The DIRAC experiment at CERN has achieved a sizeable production of
atoms and has significantly improved the precision on its lifetime
determination. From a sample of 21227 atomic pairs, a 4% measurement of the
S-wave scattering length difference
has been attained, providing an important test of Chiral Perturbation Theory.Comment: 6 pages, 6 figure
Coronal Shock Waves, EUV waves, and Their Relation to CMEs. I. Reconciliation of "EIT waves", Type II Radio Bursts, and Leading Edges of CMEs
We show examples of excitation of coronal waves by flare-related abrupt
eruptions of magnetic rope structures. The waves presumably rapidly steepened
into shocks and freely propagated afterwards like decelerating blast waves that
showed up as Moreton waves and EUV waves. We propose a simple quantitative
description for such shock waves to reconcile their observed propagation with
drift rates of metric type II bursts and kinematics of leading edges of coronal
mass ejections (CMEs). Taking account of different plasma density falloffs for
propagation of a wave up and along the solar surface, we demonstrate a close
correspondence between drift rates of type II bursts and speeds of EUV waves,
Moreton waves, and CMEs observed in a few known events.Comment: 30 pages, 15 figures. Solar Physics, published online. The final
publication is available at http://www.springerlink.co
First measurement of the atom lifetime
The goal of the DIRAC experiment at CERN (PS212) is to measure the
atom lifetime with 10% precision. Such a measurement would yield a
precision of 5% on the value of the -wave scattering lengths
combination . Based on part of the collected data we present a first
result on the lifetime, s, and
discuss the major systematic errors. This lifetime corresponds to
.Comment: 18 pages, 6 figure
The bound mu+ mu- system
We consider the hyperfine structure, the atomic spectrum and the decay
channels of the bound mu+ mu- system (dimuonium). The annihilation lifetimes of
low-lying atomic states of the system lie in the nanosecond range range. The
decay rates could be measured by detection of the decay products (high energy
photons or electron-positron pairs). The hyperfine structure splitting of the
dimuonic system and its decay rate are influenced by electronic vacuum
polarization effects in the far time-like asymptotic region. This constitutes a
previously unexplored kinematic regime. We evaluate next--to-leading order
radiative corrections to the decay rate of low-lying atomic states. We also
obtain order alpha^5 corrections to the hyperfine splitting of the 1S and 2S
levels.Comment: 10 figures (eps format) attached, Scheduled tentatively by PRA for
Nov/Dec 199
Finite-size effect on two-particle production in continuous and discrete spectrum
The formalism allowing one to account for the effect of a finite space-time
extent of particle production region is given. Its applications to the lifetime
measurement of hadronic atoms produced by a high-energy beam in a thin target,
as well as to the femtoscopy techniques widely used to measure space-time
characteristics of the production processes, are discussed. Particularly, it is
found that the neglect of the finite-size effect on the pionium lifetime
measurement in the experiment DIRAC at CERN could lead to the lifetime
overestimation comparable with the 10% statistical error. The theoretical
systematic errors arising in the calculation of the finite-size effect due to
the neglect of non-equal emission times in the pair center-of-mass system, the
space-time coherence and the residual charge are shown to be negligible.Comment: LaTeX, 77 pages including 5 tables and 18 figures. Somewhat extended
version to be published in Phys. El. Part. At. Nuc
DIRAC: A High Resolution Spectrometer for Pionium Detection
The DIRAC spectrometer has been commissioned at CERN with the aim of
detecting atoms produced by a 24 GeV/ high intensity proton
beam in thin foil targets. A challenging apparatus is required to cope with the
high interaction rates involved, the triggering of pion pairs with very low
relative momentum, and the measurement of the latter with resolution around 0.6
MeV/. The general characteristics of the apparatus are explained and each
part is described in some detail. The main features of the trigger system,
data-acquisition, monitoring and setup performances are also given.Comment: 49 pages, 37 figures. Figures 1, 2, 5 and 28 are removed because of
size limitations imposed by hep-ex. They don't offer essential information.
Latex class file 'elsart.cls' also provide
Evidence for -atoms with DIRAC
We present evidence for the first observation of electromagnetically bound
-pairs (-atoms) with the DIRAC experiment at the CERN-PS.
The -atoms are produced by the 24 GeV/c proton beam in a thin Pt-target
and the and -mesons from the atom dissociation are analyzed in
a two-arm magnetic spectrometer. The observed enhancement at low relative
momentum corresponds to the production of 173 54 -atoms. The mean
life of -atoms is related to the s-wave -scattering lengths, the
measurement of which is the goal of the experiment. From these first data we
derive a lower limit for the mean life of 0.8 fs at 90% confidence level.Comment: 15 pages, 9 figure
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