Search results for "instability"

Nonlinear electrostatic oscillations in a cold magnetized electron-positron plasma

2017

We study the spatio-temporal evolution of the nonlinear electrostatic oscillations in a cold magnetized electron-positron (e-p) plasma using both analytics and simulations. Using a perturbative method we demonstrate that the nonlinear solutions change significantly when a pure electrostatic mode is excited at the linear level instead of a mixed upper-hybrid and zero-frequency mode that is considered in a recent study. The pure electrostatic oscillations undergo phase mixing nonlinearly. However, the presence of the magnetic field significantly delays the phase-mixing compared to that observed in the corresponding unmagnetized plasma. Using 1D PIC simulations we then analyze the damping of t…

A thermoelastic instability problem for axially moving plates

2016

Problems of stability and deformation of a moving web, traveling between a system of rollers at a constant velocity are considered. The plate is subjected to a combined thermomechanical loading, including pure mechanical in-plane tension and also centripetal forces. Thermal strains corresponding to thermal tension and bending of the plate are accounted for. The problem of out-of-plane thermomechanical divergence (buckling) is reduced to an eigenvalue problem, which is studied analytically.

Numerical 3D study of FZ growth: dependence on growth parameters and melt instability

2001

Three-dimensional modelling of the floating zone (needle-eye) crystal growth process is carried out to analyse numerically the stability of the melt flow and the influence of the crystal rotation rate and inductor slit width on the 3D flow field and on the grown crystal resistivity. The unsteadiness of the melt is simulated and it is found that for the considered growth parameters a steady-state flow can be a reasonable approximation to the unsteady melt motion. The parametric studies have shown that increasing the rotation rate essentially changes the flow pattern and weakens the rotational striations, while the inductor slit width has a more local influence on these characteristics.

Elementi di pericolosità geologica dell’offshore del margine calabro-ionico

2008

Time-Resolved study of network self-organization from a biopolymeric solution

1991

Time-resolved studies of network self-organization from homogeneous solutions of the representative biostructural polymer agarose are presented. Solutions are temperature quenched and observed by several techniques. Consistent with previous suggestions by the authors, experiments at concentrations up to about 1.75% w/v provide direct kinetic evidence for the occurrence of at least two distinct processes, leading, in sequence, to self-assembly. These are as follows: (a) a liquid–liquid phase separation of the solution occurring via spinodal demixing and resulting in two sets of regions that have, respectively, higher and lower than average concentrations of random-coiled polymers; and (b) th…

Demixing and polymerization in systems of anisotropic globular particles: A molecular dynamics simulation study

1991

We report a first set of results of Molecular Dynamics simulations of phase separation in a two-dimensional system of identical particles bearing attachment sites at their surface. Morphology of regions of aggregation so obtained appear similar to images of biologically self-assembled structures. Also, they evidence the relevance of the region of thermodynamic instability and of the presence and range of interaction of specific attachment sites. Particles of our system are apt to represent indifferently, though grossly, globular proteins or rigid cells, bearing specific and fixed adhesion sites at their surface. Results illustrate some basic aspects of the origin of the morphology of extend…

In the literature: April 2020

2020

Deficient DNA mismatch repair (dMMR) may be caused by germline or somatic mutations in mismatch repair genes ( MLH1 , MSH2 , MSH3 , MSH6 and PMS2 ) or through epigenetic silencing of MLH1 .1 dMMR induces a hypermutator phenotype, also known as microsatellite instability (MSI). Next-generation sequencing identifies MSI in 12 cancer types. The highest prevalence is seen in endometrial cancer (31.4%), followed by colorectal cancer (19.7%) and gastric cancer (GC, 19.1%). MSI was related to better prognosis for colorectal cancer and GC . Moreover, the dMMR/MSI hypermutator phenotype is thought to produce large numbers of immunogenic neoantigens that can be recognised by immune cells, leading to …

Regionalization processes in agricultural and environmental policies. A regional typologies comparative analysis to identifying fragile areas

2018

This paper, affecting an analysis comparative of the different regional typologies, it analyzes the concept of weakness, with reference to the phenomena of degrade and disarrangement of the grounds, inside the processes of identification of functional territorial articulations to the statistical analysis and the decisions of policy, showing as despite the existence of a fed together of interpretations none of the examined typologies both indeed able to furnish a representation suitable of the phenomenon, since the different procedures of regionalization introduce not suitable discriminatory methodologies.

Learning Curve in Surgical Treatment of Odontoid Fixation for a Series of Type II C2 Fractures

2019

The craniovertebral junction (CVJ) is a complex anatomical area upon which most of the motion of the upper cervical spine depends [1]. Because of its unique range of motion, the CVJ is subject to several types of traumatic injury; it has been shown that odontoid fractures are the most common ones in the general population and are the most common isolated spinal fractures [2]. Accounting for up to 18% of all cervical fractures, odontoid fractures are the most common ones in elderly patients [3], in whom they account for up to 60% of spinal cord injuries [4].

Considerations on the Advantages and Disadvantages of Romania's Accession to the European Union

2015

Abstract After nine years from Romania's accession to the European Union, the advantages are sustained with specific statistical markers, which could have been more positive if the effect of certain identified causes (reduced administrative ability, political instability, extended corruption, high tax evasion etc.) would have been diminished. Counterbalancing the benefits of the accession the opinion polls show the disadvantages. If a poll conducted four years prior to the accession showed that 66% of Romania's population considered that the accession to the European Union would produce positive effects, after six years from the accession things have reversed and 58% of Romanians considered…