51 research outputs found
PageRank in scale-free random graphs
We analyze the distribution of PageRank on a directed configuration model and
show that as the size of the graph grows to infinity it can be closely
approximated by the PageRank of the root node of an appropriately constructed
tree. This tree approximation is in turn related to the solution of a linear
stochastic fixed point equation that has been thoroughly studied in the recent
literature
Cytogenetics of Vitis V. Allotetraploids of V. vinifera L. x V. rotundifolia MICHX.
The allotetraploid hybrids obtained by colchicine treatment of the completely sterile F1 diploid hybrids revealed very low and erratic fertility. A great variation in the fertility between seedlings was the rule.There is no apparent relation between chromosome pairing at MI and fertility of the allotetraploid vines. Average bivalent formation in the allotetraploids varied between 25.0 and 31.1 per cell compared to the expected 39 if complete pairing occurred.In all of the allotetraploid seedlings dominance of V. rotundifolia morphological characters was evident, although several exceptions were noted.Autotetraploid clones of the two species could be hybridized only by using V. vinifera as a female and V. rotundifolia as a male parent.Crossing behaviour of the allotetraploid F1 hybrids is identical to diploid VR hybrids. Hybrids are crossable among themselves; they can be crossed successfully only as female parents to V. rotundifolia and as female or male parent to V. vinifera.A chromosomal ratio hypothesis is proposed to explain the unilateral crossability pattern between the two species and their hybrid derivaties. The alternative breeding procedures are given for testing this hypothesis
Cytogenetics of Vitis IV: Backcross derivatives of V. vinifera L. x V. rotundifolia MICHX.
Diploid ibackcross :progeny of (V. vinifera L. x V. rotundifolia MICHX.) x V. vinifera L. were studied in the present investigation.In the diploid backcross (BC1) progeny a range from completely sterile seedlings to others as fertile as standard V. vinifera varietes was obtained.Average bivalent formation at MI in the diploid BC1 progeny varied from 7.9 to 16.1. There was a relation in BC1 hyibrids between chromosomal pairing at MI and fertility of the seedlings.BC1 seedlings ,segregated for some V. rotundifolia characters (fruit quality, flavor, type of bark, tendrils, diaphragm, size of flower clusters, shape of the leaves, etc.). Wood type was the only characteristic of V. rotundifolia. which was found in all BC1 seedlings.Crossability pattern of the BC1 progeny to V. vinifera and V. rotundifolia was the same as that of F1 VR hybrids; namely, only as a female parent to V. rotundifolia and female or male to V. vinifera
Inheritance of flower type in some grape varieties (Vitis vinifera L.)
This paper presents the results and genetical analysis of crossing grape varieties Vitis vinifera L. with regard to the inheritance of flower type. From the results obtained, following conclusions could be drawn:The flower type (hermaphrodite and female) in grape varieties Vitis vinifera L. is controlled by two allels. The genetic factor for female flower is designated by sr and the factor for hermaphroditism by Sh. Factor Sf is recessive to Sh.Varieties with hermap hrodite flower type are either homozygous (Sh Sh) or heterozygous (Sh Sf) for hermaphroditism. Out of 20 tested varieUes with hermaphrodite flowers, 14 were heterozygous and 6 homozygous. The following varieties are homozygous: Datier, Smederevka, Queen of the Vineyards, Volovsko Oko, Traminer Red and Zilavka. Heterozygous varieties are: Muscat Hamburg, Chasselas Buvie, Pearl of Csaba, Chasselas White, Italia, Italian Riesling, Merlo, Beli Medenac, Bagrina, Semillon, Pinot Noir, Prokupac, Šljiva, Muscat Otonel.Varieties with functionally female flowers are probably homozygous, i. e. Sf Sf. These are: Čaus and Crveni Drenak. In all combinations of crossings, seedlings having homogametic flower type were in deficit.Considering the improvement of grape varieties it is suggested to use hermaphrodite varieties of t he genetic constitution Sh Sh
Inducing LIPSS by multi-pass and cross-directional scanning of femtosecond beam over surface of thin metal films
During interaction of femtosecond laser beam with metal surfaces, laser induced pe- riodic nanostructures, LIPSS can be formed, which may improve properties of materials. Having excellent mechanical properties, multilayer thin films, like 5x(Al/Ti)@Si, are con- venient for forming of high quality LIPSS [1] due to their multilayer structure. We have exposed the multilayer thin film metal systems 5x(Al/Ti)@Si with femtosecond beam from the laser system Coherent Mira 900 in NIR with various scanning configurations [2]. The irradiated samples have been analyzed by Tescan Mira3 SEM. The beam scanned over the surface of the samples with multi-pass and cross-directional scanning configurations with the change of polarization direction. The formation of LIPSS is most probably due to the occurence of surface plasmon polariton, which leads to the periodic distribution of energy on the sample surface. The orientation of the LIPSS is related to the direction of the beam polarization. During multi-pass scanning, LIPSS maintained its configuration. The preservation of structures occured to some extent. Depending on the accumulated energy, two forms of LIPSS were generated: “hills”, for less accumulation, and “trenches” for greater accumulation. “Hills” are non-ablative, probably are due to the build-up of the material and are parallel to the polarization direction. “Trenches” are formed by ablation and are perpendicular to the polarization direction. During cross-directional scanning, LIPSS of orthogonal directions have been generated. The value of the “hills” period was around 360 nm and the width was ∼285 nm. The values of “trenches” period fluctuated between 320 and 380 nm, while width was between 85 and 45 nm. Proposed mechanism is that, for less accumulated energy, “hills” formed, while more accumulated energy leads to the ablation and formation of “trenches”.UltrafastLight-2018 : International Conference on Ultrafast Optical Science : Book of Abstracts, October 1-5, 2018, Moscow, Russi
Collisional kinetics of non-uniform electric field, low-pressure, direct-current discharges in H
A model of the collisional kinetics of energetic hydrogen atoms, molecules,
and ions in pure H discharges is used to predict H emission
profiles and spatial distributions of emission from the cathode regions of
low-pressure, weakly-ionized discharges for comparison with a wide variety of
experiments. Positive and negative ion energy distributions are also predicted.
The model developed for spatially uniform electric fields and current densities
less than A/m is extended to non-uniform electric fields, current
densities of A/m, and electric field to gas density ratios MTd at 0.002 to 5 Torr pressure. (1 Td = V m and 1 Torr =
133 Pa) The observed far-wing Doppler broadening and spatial distribution of
the H emission is consistent with reactions among H, H,
H, and H ions, fast H atoms, and fast H molecules, and with
reflection, excitation, and attachment to fast H atoms at surfaces. The
H excitation and H formation occur principally by collisions of
fast H, fast H, and H with H. Simplifications include using a
one-dimensional geometry, a multi-beam transport model, and the average
cathode-fall electric field. The H emission is linear with current
density over eight orders of magnitude. The calculated ion energy distributions
agree satisfactorily with experiment for H and H, but are only in
qualitative agreement for H and H. The experiments successfully modeled
range from short-gap, parallel-plane glow discharges to beam-like,
electrostatic-confinement discharges.Comment: Submitted to Plasmas Sources Science and Technology 8/18/201
Fluid Models of Many-server Queues with Abandonment
We study many-server queues with abandonment in which customers have general
service and patience time distributions. The dynamics of the system are modeled
using measure- valued processes, to keep track of the residual service and
patience times of each customer. Deterministic fluid models are established to
provide first-order approximation for this model. The fluid model solution,
which is proved to uniquely exists, serves as the fluid limit of the
many-server queue, as the number of servers becomes large. Based on the fluid
model solution, first-order approximations for various performance quantities
are proposed
Luminescence Properties Of Eu3+ Doped Mayenite Under High Pressure
Europium doped mayenite (C12A7) powders of different concentrations (0.5, 1.0, 1.5, and 2.0 at.%) have been synthesized by a modified glycine/nitrate procedure - MGNP). Obtained samples were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE- SEM), and steady-state photoluminescence spectroscopy. The effect of doping concentration on photoluminescence properties of Eu3+ doped mayenite was studied and discussed. With the increasing of Eu3+ doping concentration, the red-emitting intensity exhibited behavior that increased firstly and then decreased. The optimal Eu3+ ion concentration is found to be 1.5%. High-pressure luminescence was measured in a Betsa high-pressure membrane diamond anvil cell up to 23 GPa
Laser-induced parallel structures on multilayer thin films of Ni, Pd, Ti, Ta and W
The interaction of ultrashort laser beam with metal surfaces may induce the generation of periodic structures (LIPSS) with period less than the incoming wavelength, opening wide area of application [1, 2]. The presence of the underneath layer influences the quality of the LIPSS [3] . We have exposed multilayer thin films Ni/Ti, Ni/Pd, W/Ti, Ti/Ta to femtosecond beams of various wavelengths and powers. The interactions have been performed by Mira900 fs laser of Coherent. Detailed surface morphology after irradiation was examined firstly by optical microscopy, and then by scanning electron microscopy (JEOL JSM-7500F, Tokyo, Japan). Two types of structures have been noticed. Their appearance differ in the direction against the polarization direction, in pronounced ablation and in the spatial period, enabling their grouping into LIPSS of higher and lower spatial frequencies. Surface plasmon polariton is seen as the most probable cause of periodic distribution of energy at the surface and consequently to LIPSS.Photonics Workshop (14 ; 2021 ; Kopaonik
Sympathetic cooling of and for quantum logic
We demonstrate the cooling of a two species ion crystal consisting of one
and one ion. Since the respective cooling transitions of
these two species are separated by more than 30 nm, laser manipulation of one
ion has negligible effect on the other even when the ions are not individually
addressed. As such this is a useful system for re-initializing the motional
state in an ion trap quantum computer without affecting the qubit information.
Additionally, we have found that the mass difference between ions enables a
novel method for detecting and subsequently eliminating the effects of radio
frequency (RF) micro-motion.Comment: Submitted to PR
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