Search results for "Instability"
showing 10 items of 724 documents
Stability of hydrodynamical relativistic planar jets : II. Long-term nonlinear evolution
2004
In this paper we continue our study of the Kelvin-Helmholtz (KH) instability in relativistic planar jets following the long-term evolution of the numerical simulations which were introduced in Paper I. The models have been classified into four classes (I to IV) with regard to their evolution in the nonlinear phase, characterized by the process of jet/ambient mixing and momentum transfer. Models undergoing qualitatively different non-linear evolution are clearly grouped in well-separated regions in a jet Lorentz factor/jet-to-ambient enthalpy diagram. Jets with a low Lorentz factor and small enthalpy ratio are disrupted by a strong shock after saturation. Those with a large Lorentz factor an…
Study of irregular dynamics in an economic model: attractor localization and Lyapunov exponents
2021
Cyclicity and instability inherent in the economy can manifest themselves in irregular fluctuations, including chaotic ones, which significantly reduces the accuracy of forecasting the dynamics of the economic system in the long run. We focus on an approach, associated with the identification of a deterministic endogenous mechanism of irregular fluctuations in the economy. Using of a mid-size firm model as an example, we demonstrate the use of effective analytical and numerical procedures for calculating the quantitative characteristics of its irregular limiting dynamics based on Lyapunov exponents, such as dimension and entropy. We use an analytical approach for localization of a global at…
Immune pathway upregulation and lower genomic instability distinguish EBV-positive nodal T/NK-cell lymphoma from ENKTL and PTCL-NOS
2022
Primary Epstein-Barr virus (EBV)-positive nodal T/NK-cell lymphoma (PTCL-EBV) is a poorly understood disease which shows features resembling extranodal NK/T-cell lymphoma (ENKTL) and is currently not recognized as a distinct entity but categorized as a variant of primary T-cell lymphoma not otherwise specified (PTCL-NOS). Herein, we analyzed copynumber aberrations (n=77) with a focus on global measures of genomic instability and homologous recombination deficiency and performed gene expression (n=84) and EBV miRNA expression (n=24) profiling as well as targeted mutational analysis (n=16) to further characterize PTCL-EBV in relation to ENKTL and PTCL-NOS. Multivariate analysis revealed that …
Clinical characteristics of pancreatic and biliary tract cancers in Lynch syndrome : A retrospective analysis from the Finnish National Lynch Syndrom…
2023
IntroductionPatients with Lynch syndrome (LS) have an increased lifetime risk of pancreatic cancer (PC) and biliary tract cancer (BTC). These cancers have a notoriously pessimistic prognosis due to late diagnosis and limited therapeutic options. There are limited data based on small cohorts reviewing PC and BTC in LS patients.MethodsIn this retrospective study of the Lynch Syndrome Registry of Finland (LSRFi), records of genetically verified LS patients diagnosed with PC or BTC between 1982 and 2020 were analyzed.ResultsThirty-nine patients were included: tumor(s) were in the pancreas in 26 patients, in the biliary tract in 10, and in the ampulla of Vater in three. A pathogenic germline var…
Instability of relativistic sheared jets and distinction between FRI and FRII sources
2002
We investigate the shear-driven instability of nonmagnetic relativistic jets with the bulk velocity, V , dependent on the cylindric radius, r. It is shown that instability can arise for any dependence of the velocity (or the Lorentz factor that is the same) on r. The shear-driven instability can e ectively operate in the whole volume of a jet. The growth time can be shorter than that of the Kelvin-Helmholtz instability. The considered instability leads to a turbulization of jets and can account for a distiction between the jets in the FRI and FRII sources. Urpin, V., Vadim.Urpin@uv.es
Toward a wave turbulence formulation of statistical nonlinear optics
2012
International audience; During this last decade, several remarkable phenomena inherent to the nonlinear propagation of incoherent optical waves have been reported in the literature. This article is aimed at providing a generalized wave turbulence kinetic formulation of random nonlinear waves governed by the nonlinear Schrodinger equation in the presence of a nonlocal or a noninstantaneous nonlinear response function. Depending on the amount of nonlocal (noninstantaneous) nonlinear interaction and the amount of inhomogeneous (nonstationary) statistics of the incoherent wave, different types of kinetic equations are obtained. In the spatial domain, when the incoherent wave exhibits fluctuatio…
Role of MR arthrography in shoulder micro-instability: personal experience.
2010
Muscle lesions, a frequent event in sport, often cause hematomas. In fact, both in the traumatic direct injuries, as in American football, and in the traumatic indirect ones, as in strength sports, lesions interesting leg's Muscles Cause intra- and extramuscular hematomas. A diagnosis in a short time, allow LIS to evaluate the lesion rank and plan a surgery approach. Authors present high resolution Ultrasound (HRSU) as a new diagnostic method for this kind of lesion. It allows us to confirm clinic diagnosis, define the lesion's areas and follow-up. Moreover, HRSU has all important role in therapy, promoting in real time the blood's aspiration from lesion's area. Three phases after trauma, d…
The Determinants of the Volatility of Fiscal Policy Discretion
2014
We investigate the determinants of the volatility of fiscal policy discretion. Using a linear dynamic panel dataset model for 104 countries from 1980 to 2006 and a system-GMM estimator,we find that more government instability, less democracy and presidentialist systems increase the volatility of the discretionary component of fiscal policy. Additionally, we show that countries with a larger size, a smaller degree of financial openness, and a stable exchange rate system are more insured against the uncertainty about the conduct of fiscal policy. Our results are robust to various regional dummy variables, diferent sub-sets of countries and the presence of high inflation and crisis episodes.
General relativistic simulations of pasive-magneto-rotational core collapse with microphysics
2007
This paper presents results from axisymmetric simulations of magneto-rotational stellar core collapse to neutron stars in general relativity using the passive field approximation for the magnetic field. These simulations are performed using a new general relativistic numerical code specifically designed to study this astrophysical scenario. The code is based on the conformally-flat approximation of Einstein's field equations and conservative formulations of the magneto-hydrodynamics equations. The code has been recently upgraded to incorporate a tabulated, microphysical equation of state and an approximate deleptonization scheme. This allows us to perform the most realistic simulations of m…
Contribution of phase-mixing of Alfvén waves to coronal heating in multi-harmonic loop oscillations
2018
This research has received funding from the Science and Technology Facilities Council (UK) through the consolidated grant ST/N000609/1 and the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation program ( grant agreement No. 647214). This work is supported by the European Research Council under the SeismoSun Research Project No. 321141 (DJP). This project has received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (grant agreement No 724326). This work used the DiRAC Data Centric system at Durham University, operated by the Institute for Computational Cosmology on behalf o…