809 research outputs found
Adatom incorporation and step crossing at the edges of 2D nanoislands
Adatom incorporation into the ``faceted'' steps bordering the 2D nanoislands
is analyzed. The step permeability and incorporation coefficients are derived
for some typical growth situations. It is shown that the step consisting of
equivalent straight segments can be permeable even in the case of fast egde
migration if there exist factors delaying creation of new kinks. The step
consisting of alternating rough and straight segments may be permeable if there
is no adatom transport between neighboring segments through the corner
diffusion.Comment: 3 pages, one figur
36 Months Survivability And Its Predictors In Patients With Chronic Heart Failure And Decreased Fraction Of Left Ventricular Ejection Depending On Sex
Aim of the work: to compare survivability parameters during 36 months and their predictors among men and women with chronic heart failure and decreased fraction of left ventricular ejection.Materials and methods: the research included 356 patients with CHF (NYHA ІІ –ІV) with decreased LVEF<40 %, 18–75 years old. Using Kaplan-Meier method, there was analyzed the survivability in men and women during 36 months, then there were analyzed independent factors that influenced survivability terms depending on sex using the multiple logistic regression.Results. Our analysis of the survivability of patients with CHF with decreased LVEF demonstrated that the cumulative survival after 3 years of observation was 49 and 51 % for men and women, respectively. The curves of 36 months survivability didn\u27t reliably differ. At the analysis of factors, associated with the bad prognosis, there were observed differences between groups of men and women with CHF. Thus, in men the predictors of 36 month survival were: the thickness of the right ventricle wall, size of the right atrium, end-diastolic volume and end-systolic volume of LV, indices of EDV and ESV of LV, urinary acid level, value of LVEF. In women the predictors of survivability during 3 years were the following parameters: BMI, DM type 2 in an anamnesis, end-diastolic size of LV, end-systolic size of LV, blood glucose level, LVEF.Conclusion. The survivability of men and women with CHF with decreased LVEF during 36 months didn\u27t reliably differ and was 49 and 51 % respectively. But predictors of the lethal outcome in men and women essentially differed during 36 months, and their number is essentially higher in men
Elastic Mid-Infrared Light Scattering: a Basis for Microscopy of Large-Scale Electrically Active Defects in Semiconducting Materials
A method of the mid-IR-laser microscopy has been proposed for the
investigation of the large-scale electrically and recombination active defects
in semiconductors and non-destructive inspection of semiconductor materials and
structures in the industries of microelectronics and photovoltaics. The basis
for this development was laid with a wide cycle of the investigations on the
low-angle mid-IR-light scattering in semiconductors. The essence of the
technical idea was to apply the dark-field method for spatial filtering of the
scattered light in the scanning mid-IR-laser microscope. This approach enabled
the visualization of large-scale electrically active defects which are the
regions enriched with ionized electrically active centers. The photoexcitation
of excess carriers within a small volume located in the probe mid-IR-laser beam
enabled the visualization of the large-scale recombination-active defects like
those revealed in the optical or electron beam induced current methods. Both
these methods of the scanning mid-IR-laser microscopy are now introduced in
detail in the present paper as well as a summary of techniques used in the
standard method of the lowangle mid-IR-light scattering itself. Besides the
techniques for direct observations, methods for analyses of the defect
composition associated with the mid-IR-laser microscopy are also discussed in
the paper.Comment: 44 pages, 13 figures. A good oldi
GTO complex implementation technology for educational system
The study analyzes practical experience of the GTO Complex implementation project at Belgorod State National Research University with a special emphasis on the GTO Complex implementation process control mechanism including the following modules: progress test, regulatory, design and corporate management module
Discovery of the new class I methanol maser transition at 23.4 GHz
We report the first detection of a methanol maser in the 10(1)-9(2)A-
transition at 23.4 GHz, discovered during the H2O southern Galactic Plane
Survey (HOPS) with the 22-m Mopra radio telescope. In the region covered by
HOPS, the 23.4 GHz maser was found at only one location, G357.97-0.16, which
was also a prominent source of maser emission in the J(2)-J(1)E series near 25
GHz. The Australia Telescope Compact Array (ATCA) was used to follow up these
detections at high angular resolution and prove the maser nature of the
observed emission. The analysis shows that the new methanol maser at 23.4 GHz
is a class I maser, which has properties similar to the 9.9 and 25 GHz masers
(i.e. traces strong shocks with higher than average temperature and density).
All class I masers were found to originate at the same spatial location (within
the measurement uncertainty of 0.5 arcseconds) in the vicinity of the dominant
infrared source, but at a clearly distinct position from nearby OH, H2O and
class II methanol masers at 6.7 GHz. All maser species are distributed
approximately on a line, but it is not clear at present whether this has any
physical significance. We also detected a weak (1.3 mJy) continuum source at 25
GHz near the OH maser (at the most northern site, associated with a class II
methanol maser and an H2O maser renowned for its extremely wide spread of
velocity components). The continuum source has not been reported at lower
frequencies and is therefore a candidate hypercompact HII region. We also used
the ATCA to find the strongest and only fifth known 9.9 GHz maser towards
G357.97-0.16 and another 23.4 GHz maser towards G343.12-0.06 not seen in HOPS.Comment: 7 pages, 2 figures, 2 tables, accepted by MNRA
How do methanol masers manage to appear in the youngest star vicinities and isolated molecular clumps?
General characteristics of methanol (CH3OH) maser emission are summarized. It
is shown that methanol maser sources are concentrated in the spiral arms. Most
of the methanol maser sources from the Perseus arm are associated with embedded
stellar clusters and a considerable portion is situated close to compact HII
regions. Almost 1/3 of the Perseus Arm sources lie at the edges of optically
identified HII regions which means that massive star formation in the Perseus
Arm is to a great extent triggered by local phenomena. A multiline analysis of
the methanol masers allows us to determine the physical parameters in the
regions of maser formation. Maser modelling shows that class II methanol masers
can be pumped by the radiation of the warm dust as well as by free-free
emission of a hypercompact region hcHII with a turnover frequency exceeding 100
GHz. Methanol masers of both classes can reside in the vicinity of hcHIIs.
Modelling shows that periodic changes of maser fluxes can be reproduced by
variations of the dust temperature by a few percent which may be caused by
variations in the brightness of the central young stellar object reflecting the
character of the accretion process. Sensitive observations have shown that the
masers with low flux densities can still have considerable amplification
factors. The analysis of class I maser surveys allows us to identify four
distinct regimes that differ by the series of their brightest lines.Comment: 8 pages, 4 figures, invited presentation at IAU242 "Astrophysical
Masers and their environments
Frontiers, challenges, and solutions in modeling of swift heavy ion effects in materials
Since a few breakthroughs in the fundamental understanding of the effects of
swift heavy ions (SHI) decelerating in the electronic stopping regime in the
matter have been achieved in the last decade, it motivated us to review the
state-of-the-art approaches in the modeling of SHI effects. The SHI track
kinetics occurs via several well-separated stages: from attoseconds in
ion-impact ionization depositing energy in a target, to femtoseconds of
electron transport and hole cascades, to picoseconds of lattice excitation and
response, to nanoseconds of atomic relaxation, and even longer macroscopic
reaction. Each stage requires its own approaches for quantitative description.
We discuss that understanding the links between the stages makes it possible to
describe the entire track kinetics within a multiscale model without fitting
procedures. The review focuses on the underlying physical mechanisms of each
process, the dominant effects they produce, and the limitations of the existing
approaches as well as various numerical techniques implementing these models.
It provides an overview of ab-initio-based modeling of the evolution of the
electronic properties; Monte Carlo simulations of nonequilibrium electronic
transport; molecular dynamics modeling of atomic reaction on the surface and in
the bulk; kinetic Mote Carlo of atomic defect kinetics; finite-difference
methods of tracks interaction with chemical solvents describing etching
kinetics. We outline the modern methods that couple these approaches into
multiscale multidisciplinary models and point to their bottlenecks, strengths,
and weaknesses. The analysis is accompanied by examples of important results
improving the understanding of track formation in various materials.
Summarizing the most recent advances in the field of the track formation
process, the review delivers a comprehensive picture and detailed understanding
of the phenomena.Comment: to be submitte
Second-layer nucleation in coherent Stranski-Krastanov growth of quantum dots
We have studied the monolayer-bilayer transformation in the case of the
coherent Stranski-Krastanov growth. We have found that the energy of formation
of a second layer nucleus is largest at the center of the first-layer island
and smallest on its corners. Thus nucleation is expected to take place at the
corners (or the edges) rather than at the center of the islands as in the case
of homoepitaxy. The critical nuclei have one atom in addition to a compact
shape, which is either a square of i*i or a rectangle of i*(i-1) atoms, with
i>1 an integer. When the edge of the initial monolayer island is much larger
than the critical nucleus size, the latter is always a rectangle plus an
additional atom, adsorbed at the longer edge, which gives rise to a new atomic
row in order to transform the rectangle into the equilibrium square shape.Comment: 6 pages, 4 figures. Accepted version, minor change
- …