230 research outputs found
Features of ultrasound and dopplerometric endometry examination in autoimmune thyroiditis patients with abnormal uterine bleeding
Abnormal uterine bleeding occurs in 10â30% of reproductive age women. Ultrasound examination is one of the most effective methods of diagnosing lesions of the pelvic organs while it has high sensitivity (96%), but low specificity (13.8%) in relation to endometrial lesions, the informativeness of ultrasound in the diagnosis of abnormal uterine bleeding ranges from 60 to 93.3%. It had been revealed revealed that the imbalance of thyroid hormones can have a direct effect on the endometrium. Thus, the analysis of ultrasound examinations data together with dopplerometric assessment of the blood flow of the internal genital organs in autoimmune thyroiditis patients with abnormal uterine bleeding is an urgent task of modern gynecology. The purpose is to determine the features of ultrasound exanimation with Doppler assessment of the endometrium in autoimmune thyroiditis patients with abnormal uterine bleeding. Materials and methods. The patientsâ examinations were carried out from 2019 to 2022 We examined 120 patients, of whom 90 (75%) suffered from abnormal uterine bleeding and 30 (25%) did not have signs of gynecological and somatic pathology (control group). Abnormal bleeding patients average age was 36.3±3.2 years. The average age of bleeding and thyroid pathology women was 34.8±2.6 years, the control group average age was 30.7±2.9 years. Results. Echographic signs of endometrium structural changes were detected in 83 (92.2%) of abnormal nautoimmune bleeding women and in 7 (7.8%) women ultrasound signs of pathology were not detected. Significant differences were found when analyzing the results of ultrasonographic examination of patients with bleeding and bleeding + thyroid pathology. Conclusion. Ultrasound is an important method that contributes to a significant improvement in the diagnosis of isolated or combined benign uterine diseases in women with abnormal autoimmune bleeding at the background of thyroid pathology, and in most cases corresponds to the histological diagnosis
Formation and Preservation of Studentsâ Mental Health in the Process of Studying at Pedagogical Universities.
Determination of the Bending Rigidity of Graphene via Electrostatic Actuation of Buckled Membranes
The small mass and atomic-scale thickness of graphene membranes make them
highly suitable for nanoelectromechanical devices such as e.g. mass sensors,
high frequency resonators or memory elements. Although only atomically thick,
many of the mechanical properties of graphene membranes can be described by
classical continuum mechanics. An important parameter for predicting the
performance and linearity of graphene nanoelectromechanical devices as well as
for describing ripple formation and other properties such as electron
scattering mechanisms, is the bending rigidity, {\kappa}. In spite of the
importance of this parameter it has so far only been estimated indirectly for
monolayer graphene from the phonon spectrum of graphite, estimated from AFM
measurements or predicted from ab initio calculations or bond-order potential
models. Here, we employ a new approach to the experimental determination of
{\kappa} by exploiting the snap-through instability in pre-buckled graphene
membranes. We demonstrate the reproducible fabrication of convex buckled
graphene membranes by controlling the thermal stress during the fabrication
procedure and show the abrupt switching from convex to concave geometry that
occurs when electrostatic pressure is applied via an underlying gate electrode.
The bending rigidity of bilayer graphene membranes under ambient conditions was
determined to be eV. Monolayers have significantly lower
{\kappa} than bilayers
Challenges in QCD matter physics - The Compressed Baryonic Matter experiment at FAIR
Substantial experimental and theoretical efforts worldwide are devoted to
explore the phase diagram of strongly interacting matter. At LHC and top RHIC
energies, QCD matter is studied at very high temperatures and nearly vanishing
net-baryon densities. There is evidence that a Quark-Gluon-Plasma (QGP) was
created at experiments at RHIC and LHC. The transition from the QGP back to the
hadron gas is found to be a smooth cross over. For larger net-baryon densities
and lower temperatures, it is expected that the QCD phase diagram exhibits a
rich structure, such as a first-order phase transition between hadronic and
partonic matter which terminates in a critical point, or exotic phases like
quarkyonic matter. The discovery of these landmarks would be a breakthrough in
our understanding of the strong interaction and is therefore in the focus of
various high-energy heavy-ion research programs. The Compressed Baryonic Matter
(CBM) experiment at FAIR will play a unique role in the exploration of the QCD
phase diagram in the region of high net-baryon densities, because it is
designed to run at unprecedented interaction rates. High-rate operation is the
key prerequisite for high-precision measurements of multi-differential
observables and of rare diagnostic probes which are sensitive to the dense
phase of the nuclear fireball. The goal of the CBM experiment at SIS100
(sqrt(s_NN) = 2.7 - 4.9 GeV) is to discover fundamental properties of QCD
matter: the phase structure at large baryon-chemical potentials (mu_B > 500
MeV), effects of chiral symmetry, and the equation-of-state at high density as
it is expected to occur in the core of neutron stars. In this article, we
review the motivation for and the physics programme of CBM, including
activities before the start of data taking in 2022, in the context of the
worldwide efforts to explore high-density QCD matter.Comment: 15 pages, 11 figures. Published in European Physical Journal
The PHENIX Experiment at RHIC
The physics emphases of the PHENIX collaboration and the design and current
status of the PHENIX detector are discussed. The plan of the collaboration for
making the most effective use of the available luminosity in the first years of
RHIC operation is also presented.Comment: 5 pages, 1 figure. Further details of the PHENIX physics program
available at http://www.rhic.bnl.gov/phenix
The ATLAS Transition Radiation Tracker (TRT) proportional drift tube: design and performance
A straw proportional counter is the basic element of the ATLAS Transition Radiation Tracker (TRT). Its detailed properties as well as the main properties of a few TRT operating gas mixtures are described. Particular attention is paid to straw tube performance in high radiation conditions and to its operational stability
The ATLAS TRT electronics
The ATLAS inner detector consists of three sub-systems: the pixel detector spanning the radius range 4cm-20cm, the semiconductor tracker at radii from 30 to 52 cm, and the transition radiation tracker (TRT), tracking from 56 to 107 cm. The TRT provides a combination of continuous tracking with many projective measurements based on individual drift tubes (or straws) and of electron identification based on transition radiation from fibres or foils interleaved between the straws themselves. This paper describes the on and off detector electronics for the TRT as well as the TRT portion of the data acquisition (DAQ) system
Properties of Graphene: A Theoretical Perspective
In this review, we provide an in-depth description of the physics of
monolayer and bilayer graphene from a theorist's perspective. We discuss the
physical properties of graphene in an external magnetic field, reflecting the
chiral nature of the quasiparticles near the Dirac point with a Landau level at
zero energy. We address the unique integer quantum Hall effects, the role of
electron correlations, and the recent observation of the fractional quantum
Hall effect in the monolayer graphene. The quantum Hall effect in bilayer
graphene is fundamentally different from that of a monolayer, reflecting the
unique band structure of this system. The theory of transport in the absence of
an external magnetic field is discussed in detail, along with the role of
disorder studied in various theoretical models. We highlight the differences
and similarities between monolayer and bilayer graphene, and focus on
thermodynamic properties such as the compressibility, the plasmon spectra, the
weak localization correction, quantum Hall effect, and optical properties.
Confinement of electrons in graphene is nontrivial due to Klein tunneling. We
review various theoretical and experimental studies of quantum confined
structures made from graphene. The band structure of graphene nanoribbons and
the role of the sublattice symmetry, edge geometry and the size of the
nanoribbon on the electronic and magnetic properties are very active areas of
research, and a detailed review of these topics is presented. Also, the effects
of substrate interactions, adsorbed atoms, lattice defects and doping on the
band structure of finite-sized graphene systems are discussed. We also include
a brief description of graphane -- gapped material obtained from graphene by
attaching hydrogen atoms to each carbon atom in the lattice.Comment: 189 pages. submitted in Advances in Physic
Probing the Thermal Deoxygenation of Graphene Oxide using High Resolution In Situ X-Ray based Spectroscopies
Despite the recent developments in Graphene Oxide due to its importance as a
host precursor of Graphene, the detailed electronic structure and its evolution
during the thermal reduction remain largely unknown, hindering its potential
applications. We show that a combination of high resolution in situ X-ray
photoemission and X-ray absorption spectroscopies offer a powerful approach to
monitor the deoxygenation process and comprehensively evaluate the electronic
structure of Graphene Oxide thin films at different stages of the thermal
reduction process. It is established that the edge plane carboxyl groups are
highly unstable, whereas carbonyl groups are more difficult to remove. The
results consistently support the formation of phenol groups through reaction of
basal plane epoxide groups with adjacent hydroxyl groups at moderate degrees of
thermal activation (~400 {\deg}C). The phenol groups are predominant over
carbonyl groups and survive even at a temperature of 1000 {\deg}C. For the
first time a drastic increase in the density of states (DOS) near the Fermi
level at 600 {\deg}C is observed, suggesting a progressive restoration of
aromatic structure in the thermally reduced graphene oxideComment: Pagona Papakonstantinou as Corresponding author, E-mail:
[email protected]
Dynamics of mechanical waves in periodic grapheme nanoribbon assemblies
We simulate the natural frequencies and the acoustic wave propagation characteristics of graphene nanoribbons (GNRs) of the type (8,0) and (0,8) using an equivalent atomistic-continuum FE model previously developed by some of the authors, where the C-C bonds thickness and average equilibrium lengths during the dynamic loading are identified through the minimisation of the system Hamiltonian. A molecular mechanics model based on the UFF potential is used to benchmark the hybrid FE models developed. The acoustic wave dispersion characteristics of the GNRs are simulated using a Floquet-based wave technique used to predict the pass-stop bands of periodic mechanical structures. We show that the thickness and equilibrium lengths do depend on the specific vibration and dispersion mode considered, and that they are in general different from the classical constant values used in open literature (0.34 nm for thickness and 0.142 nm for equilibrium length). We also show the dependence of the wave dispersion characteristics versus the aspect ratio and edge configurations of the nanoribbons, with widening band-gaps that depend on the chirality of the configurations. The thickness, average equilibrium length and edge type have to be taken into account when nanoribbons are used to design nano-oscillators and novel types of mass sensors based on periodic arrangements of nanostructures
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