753 research outputs found
Liquid and crystal phase of dipolar fermions in two dimensions
The liquid and crystal phase of a single-component Fermi gas with dipolar
interactions are investigated using quantum Monte Carlo methods in two spatial
dimensions and at zero temperature. The dipoles are oriented by an external
field perpendicular to the plane of motion, resulting in a purely repulsive
1/r^3 interaction. In the liquid phase we calculate the equation of state as a
function of the interaction strength and other relevant properties
characterizing the Fermi-liquid behavior: effective mass, discontinuity at the
Fermi surface and pair correlation function. In the high density regime we
calculate the equation of state of the Wigner crystal phase and the critical
density of the liquid to solid first order phase transition. Close to the
freezing density we also search for the existence of a stripe phase, but such a
phase is never found to be energetically favorable.Comment: 5 pages, 5 figure
One-dimensional multicomponent Fermi gas in a trap: quantum Monte Carlo study
One-dimensional world is very unusual as there is an interplay between
quantum statistics and geometry, and a strong short-range repulsion between
atoms mimics Fermi exclusion principle, fermionizing the system. Instead, a
system with a large number of components with a single atom in each, on the
opposite acquires many bosonic properties. We study the ground-state properties
a multi-component Fermi gas trapped in a harmonic trap by fixed-node diffusion
Monte Carlo method. We investigate how the energetic properties (energy,
contact) and correlation functions (density profile and momentum distribution)
evolve as the number of components is changed. It is shown that the system
fermionizes in the limit of strong interactions. Analytical expression are
derived in the limit of weak interactions within the local density
approximation for arbitrary number of components and for one plus one particle
using an exact solution.Comment: 15 pages, 5 figure
Dipolar Drag in Bilayer Harmonically Trapped Gases
We consider two separated pancake-shaped trapped gases interacting with a
dipolar (either magnetic or electric) force. We study how the center of mass
motion propagates from one cloud to the other as a consequence of the
long-range nature of the interaction. The corresponding dynamics is fixed by
the frequency difference between the in-phase and the out-of-phase center of
mass modes of the two clouds, whose dependence on the dipolar interaction
strength and the cloud separation is explicitly investigated. We discuss Fermi
gases in the degenerate as well as in the classical limit and comment on the
case of Bose-Einsten condensed gases.Comment: Submitted to EPJD, EuroQUAM special issue "Cold Quantum Matter -
Achievements and Prospects
Shot noise in Weyl semimetals
We study the effect of inelastic processes on the magneto-transport of a
quasi-one dimensional Weyl semi-metal, using a modified Boltzmann-Langevin
approach. The magnetic field drives a crossover to a ballistic regime in which
the propagation along the wire is dominated by the chiral anomaly, and the role
of fluctuations inside the sample is exponentially suppressed. We show that
inelastic collisions modify the parametric dependence of the current
fluctuations on the magnetic field. By measuring shot noise as a function of a
magnetic field, for different applied voltage, one can estimate the
electron-electron inelastic length .Comment: 7 pages, 1 figur
Content of protein and glycoproteins, their components in the oral fluid in children with chronic gastritis, duodenitis
In the oral fl uid of children with chronic gastritis, duodenitis there is the increased protein content (up to 7.33±0.43 g/l) against the background of the decreasing level of glycoproteins (up to 0.03±0.01 mg/ml). Coeffi cient of ratio protein / glycoproteins in the oral fl uid is increased by a factor of 9510, which has shown the intensive decay of protein-carbohydrate complexes and the increasing content of the protein fragments. In the composition of glycoproteins there is the reduced amount of hexosamines (up to 0.23±0.01 mmol/l), against the background of the increasing sialic acids (up to 0.16±0.01 mmol/l) and fucose (up to 0.87±0.02 mmol/l). Coeffi cient of ratio of terminal and corpus monosaccharides in the glycoproteins of the oral fl uid in patients with chronic gastritis, duodenitis is increased by a factor of 2.41 and 3.34, as compared to the same values in the control group of children, which signifi cantly modifi es the functional properties of the protein-carbohydrate complexes
Anatomy of coronary sinus ostium
Background: The coronary sinus is the main cardiac vein and it has become a clinically important structure especially through its role in providing access for different cardiac procedures.
Materials and methods: The study was carried out on 100 randomly selected adult human cadaver hearts fixed in 10% formalin. The transverse and craniocaudal diameters of the coronary sinus ostium (CSO) were directly measured. The presence of the Thebesian valve was noted and the anatomical details of the valve were documented in each case in terms of the shape and extent of coverage of the CSO.
Results: Considerable variations in the diameter of the CSO were observed. The mean craniocaudal diameter of the CSO was 8.1 ± 1.51 mm, and the mean transverse diameter was 7.67 ± 1.72 mm. Heart specimens without Thebesian valve tended to have larger ostia. The mean craniocaudal diameter and the mean transverse diameter of the CSO were statistically larger in the specimens without Thebesian valves (p = 0.000 and p = 0.001, respectively).
Conclusions: The Thebesian valves were observed in 86 hearts, and a wide variety of their morphology was seen. The majority of the Thebesian valves were semilunar in shape (74.42%). The extent to which the valve covered the ostium was variable, including remnant valves that covered < 15% of the CSO (35%), and valves that were large and covered at least 75% of the CSO (22.09%). In 3 specimens the valve completely occluded the ostium.
PARP1 is a Versatile Factor in the Regulation of mRNA Stability and Decay
PARP1 is an abundant nuclear protein with many pleiotropic functions involved in epigenetic and transcriptional controls. Abundance of mRNA depends on the balance between synthesis and decay of a particular transcript. PARP1 binds RNA and its depletion results in increased expression of genes involved in nonsense-mediated decay, suggesting that PARP1 might be involved in mRNA stability. This is of interest considering RNA binding proteins play key roles in post-transcriptional processes in all eukaryotes. We tested the direct impact of PARP1 and PARylation on mRNA stability and decay. By measuring the half-lives of two PARP1-mRNA targets we found that the half-lives were significantly decreased in PARP1-depleted cells. PARP1 depletion impacted both the synthesis of nascent mRNA and the stability of mature mRNAs. PARylation impacted the production of nascent mRNA and the stability of mature mRNA, albeit to a lesser extent than PARP1 KD. PARylation enhanced the impact of PARP1 depletion. These studies provide the first direct comparative role of PARP1 and PARylation in RNA stability and decay, adding a new dimension as to how PARP1 regulates gene expression. These studies present a platform to begin to tease out the influence of PARP1 at each step of RNA biogenesis and decay to fine-tune gene expression
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