37 research outputs found
Ising Universality in Three Dimensions: A Monte Carlo Study
We investigate three Ising models on the simple cubic lattice by means of
Monte Carlo methods and finite-size scaling. These models are the spin-1/2
Ising model with nearest-neighbor interactions, a spin-1/2 model with
nearest-neighbor and third-neighbor interactions, and a spin-1 model with
nearest-neighbor interactions. The results are in accurate agreement with the
hypothesis of universality. Analysis of the finite-size scaling behavior
reveals corrections beyond those caused by the leading irrelevant scaling
field. We find that the correction-to-scaling amplitudes are strongly dependent
on the introduction of further-neighbor interactions or a third spin state. In
a spin-1 Ising model, these corrections appear to be very small. This is very
helpful for the determination of the universal constants of the Ising model.
The renormalization exponents of the Ising model are determined as y_t = 1.587
(2), y_h = 2.4815 (15) and y_i = -0.82 (6). The universal ratio Q =
^2/ is equal to 0.6233 (4) for periodic systems with cubic symmetry.
The critical point of the nearest-neighbor spin-1/2 model is K_c=0.2216546
(10).Comment: 25 pages, uuencoded compressed PostScript file (to appear in Journal
of Physics A
A Compiled Catalogue of Spectroscopically Determined Elemental Abundances for Stars with Accurate Parallaxes. I.Magnesium
We present a compiled catalogue of effective temperatures, surface gravities,
iron and magnesium abundances, distances, velocity components, and orbital
elements for stars in the solar neighborhood. The atmospheric parameters and
iron abundances are averages of published values derived from model synthetic
spectra for a total of about 2000 values in 80 publications. Our relative
magnesium abundances were found from 1412 values in 31 publications for 876
dwarfs and subgiants using a three-step iteration averaging procedure, with
weights assigned to each source of data as well as to each individual
determination and taking into account systematic deviations of each scale
relative to the reduced mean scale. The estimated assumed completeness for data
sources containing more than five stars, up to late December 2003, exceeds 90%.
For the vast majority of stars in the catalogue, the spatial velocity
components were derived from modern high-precision astrometric observations,
and their Galactic orbit elements were computed using a three-component model
of the Galaxy, consisting of a disk, a bulge, and a massive extended halo.Comment: Accepted for Astron. Rep. 2005, v.49, No.5, p.405-416, 12 pages, 10
figure
PDCD4 and CDX-2 as immunohistochemical markers of gastric mucosa atrophy in chronic gastritis
The aim of the work is to evaluate the possibility of using immunohistochemical markers PDCD4 and CDX-2 to diagnose atrophy of the gastric mucosa in chronic gastritis and increase the informative value of biopsy examination.Цель работы – оценка возможности использования иммуногистохимических маркеров PDCD4 и CDX-2 для диагностики атрофии слизистой оболочки желудка при хроническом гастрите, повышения информативности биопсийного исследования
Evaluation of the CDX2 protein distribution in the gastric mucosa in chronic gastritis by a semi-quantitative index and its reproducibility
The purpose of the study was to assess the reproducibility of the semi-quantitative CDX2 index calculation in chronic atrophic gastritis stages I-IV.Цель исследования – оценка воспроизводимости методики расчета полуколичественного индекса CDX2 при I-IV стадиях хронического атрофического гастрита
Formation of Galactic Systems in Light of the Magnesium Abundance in Field Stars: The Thick Disk
The space velocities and Galactic orbital elements of stars calculated from
the currently available high-accuracy observations in our summary catalog of
spectroscopic magnesium abundances in dwarfs and subgiants in the solar
neighborhood are used to identify thick-disk objects. The relative magnesium
abundances in thick-disk stars are shown to lie within the range
0.0<[Mg/Fe]<0.5 and to decrease with increasing metallicity starting from
[Fe/H]=-1.0. This is interpreted as evidence for a longer duration of the star
formation process in the thick disk. We have found vertical gradients in
metallicity (grad_Z[Fe/H]=-0.13\pm 0.04 kpc^{-1}) and relative magnesium
abundance (grad_Z [Mg/Fe]=0.06\pm 0.02 kpc^{-1}), which can be present in the
subsystem only in the case of its formation in a slowly collapsing protogalaxy.
The large spread in relative magnesium abundance (-0.3<[Mg/Fe]<0.5) in the
stars of the metal-poor "tail" of the thick disk which constitute 8% of the
subsystem, can be explained in terms of their formation inside isolated
interstellar clouds that interacted weakly with the matter of a single
protogalactic cloud. We have found a statistically significant negative radial
gradient in relative magnesium abundance in the thick disk (grad_R
[Mg/Fe]=-0.03\pm 0.01 kpc^{-1}) instead of the expected positive gradient. The
smaller perigalactic orbital radii and the higher eccentricities for
magnesium-richer stars, which among other stars, are currently located in a
small volume of the Galactic space near the Sun are assumed to be responsible
for the gradient inversion. A similar but statistically less significant
inversion is also observed in the subsystem for the radial metallicity
gradient.Comment: Accepted for 2005, Astronomy Letters, Vol. 31, No. 8, P.515-527; 14
pages, 6 figure
Consensus as a method for evaluating the reproducibility of gastric intraepithelial neoplasia/dysplasia: possibility of using in the process of continuing professional education of pathologists
The reproducibility of the Modified Vienna classification of gastrointestinal neoplasia on the gastric mucosal biopsies was evaluated by using the kappa statistic. The work of a group of pathologists-experts was organized in the remote access mode with a demonstration of 26 cases (98 microphotographs) and an evaluation of the diagnostic category of gastric intraepithelial neoplasia/dysplasia. Different levels of agreement between the opinions of the participating experts have been established in depending on the diagnostic difficulty level. The kappa level ranged from 0.2 (poor agreement) to 0.66 (good agreement) and was depending from the chosen method of correction of the result. , This circumstance contributed to the formation of opinion that the diagnoses indefinite neoplasia/dysplasia-low and high grade neoplasia/dysplasia were the most difficult decisions. Possible reasons which reduce the level of consistency of pathologists are discussed.Методами каппа-статистики проведена оценка воспроизводимости Модифицированной Венской классификации неоплазий пищеварительного тракта на материале биопсий слизистой оболочки желудка. В дистанционном режиме организована работа группы патологоанатомов-экспертов с демонстрацией 26 наблюдений (98 фотографий) с оценкой диагностической категории интраэпителиальной неоплазии/дисплазии слизистой оболочки желудка. Установлены различные уровни совпадения мнения участвовавших экспертов в зависимости от сложности диагностической задачи. Уровень каппа колебался от 0,2 (плохое согласие) до 0,66 (хорошее согласие) в зависимости от выбранного метода коррекции результата, что способствовало формированию мнения о наиболее сложных с точки зрения согласованного мнения диагностических категориях, находящихся в ряду неопределенная неоплазия/ дисплазия – неоплазия/дисплазия низкой и высокой степени. обсуждаются возможные причины, снижающие уровень согласованности патологоанатомов-экспертов
Molecular and cellular basis in prediction of gastric cancer: a multidisciplinary research experience
A self-review of the results of multidisciplinary studies on the development of a predictive system for intestinal type gastric cancer (adenocarcinoma) is present. The authors' studies carried out in 2007-2017 in light of recent concepts of prediction and prevention of gastric cancer are discussed. The predictive model for gastric cancer is proposed. This includes an evaluation of inflammatory cytokine genes nucleotide polymorphisms, aberrant expression of microRNA, detection of tissue patterns of gastric atrophy and intestinal metaplasia (metaplastic atrophy), principles and possibilities of pathomorphological monitoring.Представлен самообзор результатов мультидисциплинарных исследований по разработке предиктивной системы в отношении рака желудка кишечного типа (аденокарциномы). Обсуждаются исследования авторов, выполненные в 2007-2017 годах в аспекте современных концепций предикции и превенции рака желудка. Предложена модель предикции рака желудка, включающая оценку нуклеотидных замен в генах воспалительных цитокинов, аберрантную экспрессию микроРНК, детекцию тканевых паттернов атрофии и метапластической атрофии слизистой оболочки желудка, принципы и возможности патоморфологического мониторинга