200 research outputs found
Risk-oriented internal control: The essence, management methods at small enterprises
The research topic relevance is inspired by necessity to develop theoretical and methodical provisions on the internal control system, risk-based management at small enterprises and to prove application feasibility, using economic-mathematical methods its implementation. The purpose of this research is to develop theoretical and methodical approaches to internal control system formation in small businesses, generating reliable and relevant information on the commercial organization activities, enabling risks identification. The leading approach to study this problem is situational and systematic in the frame of theory and methodology internal control at small businesses in the risk-based management system, allowing to analyze the impact of various risks on small enterprises activity and to systematize obtained results. According to the study results, there were proved the implementing internal control feasibility at small businesses, presenting the author's systematization and classification of internal and external risks in small companies, identifying organizational and methodological approaches to risk-based internal control development; implemented the adaptation of existing economic-mathematical methods within risk-based internal control at small businesses. The article can be useful for practical and scientific workers in the field of company’s internal control, teachers, postgraduates, undergraduates and students, studying Economics and Management at higher educational institutions. © 2016 Piskunov et al
The charge ordered state in half-doped Bi-based manganites studied by O and Bi NMR
We present a Bi and O NMR study of the Mn electron spin
correlations developed in the charge ordered state of
BiSrMnO and BiCaMnO. The unusually
large local magnetic field indicates the dominant
character of the lone electron pair of Bi-ions in both compounds. The
mechanism connecting the character of the lone pairs to the high
temperature of charge ordering is still not clarified. The observed
difference in for BiSrMnO to
BiCaMnO is probably due to a decrease in the canting of
the staggered magnetic moments of Mn-ions from. The modification of the
O spectra below demonstrates that the line due to the apical
oxygens is a unique local tool to study the development of the Mn spin
correlations. In the AF state the analysis of the O spectrum of
PrCaMnO and BiSrMnO prompts us to
try two different theoretical descriptions of the charge-ordered state, a
site-centered model for the first manganite and a bond-centered model for the
second one.Comment: 10 pages, 7 figure
Diamagnetism above Tc in underdoped Bi2.2Sr1.8Ca2Cu3O10+d
Single crystals of (Bi2223) with were grown by a traveling solvent floating
zone method in order to investigate the superconducting properties of highly
underdoped Bi2223.Grown crystals were characterized by X-ray diffraction, DC
susceptibility and resistivity measurements, confirming Bi2223 to be the main
phase.The crystals were annealed under various oxygen partial pressures to
adjust their carrier densities from optimally doped to highly underdoped.The
fluctuation diamagnetic component above the superconducting transition
temperature extracted from the anisotropic normal state
susceptibilities () and ()
was found to increase with underdoping, suggesting a decrease in the
superconducting dimensionality and/or increase in the fluctuating vortex liquid
region.Comment: 6 pages, 7 figures, corrected fig.4 and references, published in J.
Phys. Soc. Jpn. 79, 114711 (2010
Doping Dependence of Anisotropic Resistivities in Trilayered Superconductor Bi2Sr2Ca2Cu3O10+delta (Bi-2223)
The doping dependence of the themopower, in-plane resistivity rho_ab(T),
out-of-plane resistivity rho_c(T), and susceptibility has been systematically
measured for high-quality single crystal Bi2Sr2Ca2Cu3O10+delta. We found that
the transition temperature Tc and pseudogap formation temperature T_rho_c*,
below which rho_c shows a typical upturn, do not change from their optimum
values in the "overdoped" region, even though doping actually proceeds. This
suggests that, in overdoped region, the bulk is determined by the always
underdoped inner plane, which have a large superconducting gap, while the
carriers are mostly doped in the outer planes, which have a large phase
stiffness.Comment: 5 pages, 4 figures. to be published in PR
New Spectroscopic Observations of the Post-AGB Star V354Lac=IRAS22272+5435
The strongest absorption features with the lower-level excitation potentials
eV are found to be split in the high-resolution optical
spectra of the post-AGB star V354 Lac taken in 2007--2008. Main parameters,
T=5650 K, =0.2, =5.0 km/s, and the abundances of 22
chemical elements in the star's atmosphere are found. The overabundance of the
-process chemical elements (Ba, La, Ce, Nd) in the star's atmosphere is
partly due to the splitting of strong lines of the ions of these metals. The
peculiarities of the spectrum in the wavelength interval containing the LiI
6707 \AA{} line can be naturally explained only by taking the
overabundances of the CeII and SmII heavy-metal ions into account. The best
agreement with the synthetic spectrum is achieved assuming (LiI)=2.0,
(CeII)=3.2, and (SmII)=2.7. The velocity field both in the
atmosphere and in the circumstellar envelope of V354 Lac remained stationary
throughout the last 15 years of our observations.Comment: 16 pages, 6 figures, 2 table
Evolutionary stage of the spectral variable BD+48 1220=IRAS 05040+4820
Based on high-resolution observations (R=60000 and 75000), we have studied
the optical spectral variability of the star BD+48 1220 (IRAS05040+4820). We
have measured the equivalent widths of numerous absorption lines of neutral
atoms and ions at wavelengths from 4500 to 6760 AA, as well as the
corresponding radial velocities. We use model atmospheres to determine
Teff=7900K, log g=0.0, microturbulence velocity xi_t=6.0, and the abundances
for 16 elements. The star's metallicity differs little from the solar value:
[Fe/H]=-0.10 dex. The main peculiarity of the chemical composition of the star
is a large He-excess, derived from the HeI 5876 A absorption, [He/H]=+1.04, and
the equally large O-excess, [O/Fe]=+0.72 dex. The C-excess is small,
[C/Fe]=+0.09 dex, and the ratio [C/O] 1. We obtained a revised relation
for the light-metal abundances: [Na/Fe]=+0.87 with [Mg/Fe]=-0.31. The barium
abundance is low, [Ba/Fe]=-0.84. The radial velocity of the star measured from
photospheric absorption lines over three years of observations varies in the
interval V_sun = -(7 - 15) km/s. Time variable differential line shifts have
been revealed. The entire set of available data (the luminosity Mv~-5m,
velocity V_lsr~-20 km/s, metallicity [Fe/H]=-0.10, and peculiarities of the
optical spectrum and chemical composition) confirms the status of BD+48 1220 as
a post-AGB star with He- and O-excesses belonging to the Galactic disk.Comment: 42 pages, 7 figures, 6 tables, accepted by Astronomy Report
A spectroscopic analysis of the chemically peculiar star HD207561
In this paper we present a high-resolution spectroscopic analysis of the
chemically peculiar star HD207561. During a survey programme to search for new
roAp stars in the Northern hemisphere, Joshi et al. (2006) observed significant
photometric variability on two consecutive nights in the year 2000. The
amplitude spectra of the light curves obtained on these two nights showed
oscillations with a frequency of 2.79 mHz [P~6-min]. However, subsequent
follow-up observations could not confirm any rapid variability. In order to
determine the spectroscopic nature of HD207561, high-resolution spectroscopic
and spectro-polarimetric observations were carried out. A reasonable fit of the
calculated Hbeta line profile to the observed one yields the effective
temperature (Teff) and surface gravity (log g) as 7300 K and 3.7 dex,
respectively. The derived projected rotational velocity (vsin i) for HD207561
is 74 km/sec indicative of a relatively fast rotator. The position of HD207561
in the H-R diagram implies that this is slightly evolved from the main-sequence
and located well within the delta-Scuti instability strip. The abundance
analysis indicates the star has slight under-abundances of Ca and Sc and mild
over-abundances of iron-peak elements. The spectro-polarimetric study of
HD207561 shows that the effective magnetic field is within the observational
error of 100 gauss (G). The spectroscopic analysis revealed that the star has
most of the characteristics similar to an Am star, rather than an Ap star, and
that it lies in the delta-Scuti instability strip; hence roAp pulsations are
not expected in HD207561, but low-overtone modes might be excited.Comment: 8 pages, 7 figures, 3 tables. Accepted for pubblication in MNRA
V2324Cyg - an F-type star with fast wind
For the first time high-resolution optical spectroscopy of the variable star
V2324Cyg associated with the IR-source IRAS20572+4919 is made. More than 200
absorption features (mostly FeII, TiII, CrII, YII, BaII, and YII) are
identified within the wavelength interval 4549-7880AA. The spectral type and
rotation velocity of the star are found to be F0III and Vsini=69km/s,
respectively. HI and NaID lines have complex PCyg-type profiles with an
emission component. Neither systematic trend of radial velocity Vr with line
depth Ro nor temporal variability of Vr have been found. We determined the
average heliocentric radial velocity Vr=-16.8\pm 0.6km/s. The radial velocities
inferred from the cores of the absorption components of the H and NaI
wind lines vary from -140 to -225km/s (and the expansion velocities of the
corresponding layers, from about 120 to 210km/s). The maximum expansion
velocity is found for the blue component of the split H absorption:
450km/s for December 12, 1995. The model atmospheres method is used to
determine the star's parameters: Teff=7500K, log g=2.0, =6.0km/s, and
metallicity, which is equal to the solar value. The main peculiarity of the
chemical abundances pattern is the overabundance of lithium and sodium. The
results cast some doubt on the classification of V2324Cyg as a post-AGB star.Comment: 28 pages, 6 figure
Oxygen abundances in unevolved metal-poor stars from near-UV OH lines
We have performed a detailed oxygen abundance analysis of 23 metal-poor
(-3.0<[Fe/H]<-0.3) unevolved halo stars and one giant through the OH bands in
the near UV, using high-resolution echelle spectra. Oxygen is found to be
overabundant with respect to iron in these stars, with the [O/Fe] ratio
increasing from 0.6 to 1 between [Fe/H]=-1.5 and -3.0. The behavior of the
oxygen overabundance with respect to [Fe/H] is similar to that seen in previous
works based on OI IR triplet data (Abia and Rebolo 1989; Tomkin et al. 1992;
Cavallo, Pilachowski, and Rebolo 1997). Contrary to the previously accepted
picture, our oxygen abundances, derived from low-excitation OH lines, agree
well with those derived from high-excitation lines of the triplet. For nine
stars in common with Tomkin et al. we obtain a mean difference of 0.00+/-0.11
dex with respect to the abundances determined from the triplet using the same
stellar parameters and model photospheres. For four stars in our sample we have
found measurements of the [OI] 6300 A line in the literature, from which we
derive oxygen abundances consistent (average difference 0.09 dex) with those
based on OH lines, showing that the long standing controversy between oxygen
abundances from forbidden and permitted lines in metal-poor unevolved stars can
be resolved. Our new oxygen abundances show a smooth extension of the
Edvardsson et al.'s (1993) [O/Fe] versus metallicity curve to much lower
abundances, with a slope -0.31+/- 0.11 (taking into account the error bars in
both oxygen abundances and metallicities) in the range -3<[Fe/H]<-1.Comment: 17 pages, 8 figures, 3 table
73Ge NMR spectra in germanium single crystals with different isotopic composition
We have studied the influence of isotopic disorder on the local deformations in Ge single crystals from both experimental and calculation points of view. The nuclear magnetic resonance (NMR) spectra of 73Ge nuclei (the nuclear spin equals 9/2) in perfect single crystals of germanium with different isotopic content were measured at temperatures 80, 300 and 450 K. Abnormal broadening of the spectrum was found to occur when the magnetic field was aligned along the [111] axis of a crystal. The observed specific angular dependence of the quadrupole broadening was attributed to isotopic disorder among atoms of germanium sited around the 73Ge NMR probe. Local lattice deformations in germanium crystal lattice due to isotopic impurity atoms were calculated in the framework of the adiabatic bond charge model. The results obtained were applied to study random noncubic crystal field interactions with the nuclear quadrupole moments and corresponding effects in NMR spectra. Simulated second and fourth moments of resonance frequency distributions caused by the magnetic dipole-dipole and electric quadrupole interactions are used to analyze the lineshapes, theoretical predictions agree qualitatively with the experimental data. © Springer-Verlag 1999
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