1,017 research outputs found
Stellar kinematics of X-ray bright massive elliptical galaxies
We discuss a simple and fast method for estimating masses of early-type
galaxies from optical data and compare the results with X-ray derived masses.
The optical method relies only on the most basic observables such as the
surface brightness and the line-of-sight velocity dispersion
profiles and provides an anisotropy-independent estimate of the
galaxy circular speed . The mass-anisotropy degeneracy is effectively
overcome by evaluating at a characteristic radius defined
from {\it local} properties of observed profiles. The sweet radius is expected to lie close to , where , and not
far from the effective radius . We apply the method to a sample of
five X-ray bright elliptical galaxies observed with the 6-m telescope BTA-6 in
Russia. We then compare the optical -estimate with the X-ray derived
value, and discuss possible constraints on the non-thermal pressure in the hot
gas and configuration of stellar orbits. We find that the average ratio of the
optical -estimate to the X-ray one is equal to with
scatter, i.e. there is no evidence for the large non-thermal pressure
contribution in the gas at . From analysis of the Lick
indices H, Mgb, Fe5270 and Fe5335, we calculate the mass of the stellar
component within the sweet radius. We conclude that a typical dark matter
fraction inside in the sample galaxies is for the
Salpeter IMF and for the Kroupa IMF.Comment: accepted for publication in MNRA
The optimal form of the scanning near-field optical microscopy probe
A theoretical approach to determine the optimal form of the near-field
optical microscope probe is proposed. An analytical expression of the optimal
probe form with subwavelength aperture has been obtained. The advantages of the
probe with the optimal form are illustrated using numerical calculations. The
conducted calculations show 10 times greater light throughput and the reception
possibility of the more compactly localized light at the output probe aperture
which could indicate better spatial resolution of the optical images in
near-field optical technique using optimal probe.Comment: 12 pages, 6 figure
Use of Physicochemical Method for Evaluation of Mucilage Producing Ability of the Linum Usitatissimum L. Seeds
Abstract In the modern medicine of many European countries flax is used as a medicament with a wide range of use. Wholesome effect of flax seeds is determined by the large amount of enveloping substances. This property is connected with content of mucilage up to 10% and glycoside linamarin. Flaxseed polysaccharides also possess antiinflammatory effect. Furthermore, mucilage production can be a chemosystematic characteric of intraspecific taxons. In literature intervarietal variability data is limited. Therefore, comparative evaluation of mucilage producing ability of flax seeds with different morphotypes is of interest. The research of micromorphological characteristics of seed coat and mucilage production dynamics was carried out and it was established that mucilage-producing cells are localized predominantly in the external layer of seed coat. It was established that Bahmalskiy, Nebesnyj, Kustanayskiy yantar varieties possess the highest level of mucilage production. Morphotype and varietal specificity of mucilage production are determined, consequently it can be used as a marker feature of L. usitatissimum new forms. The proposed technique is based on the determination of seed physicochemical characteristics and can be used for express analysis of the vegetal samples and their differentiation by the directions of use: as a fatty oil or mucilage-containing raw material.
Keywords: Linum usitatissimum L. varieties, seeds, mucilage production, hydration dynamics, physicochemical method
Nephelometric Method for Determination of Growth Parameters of Chlorella Culture
Nephelometric method for the determination of growth parameters of chlorella culture using a photoelectric colorimeter was described. Use of photoelectric colorimeter for cell counting in suspension requires periodic calibration of meter readings using chlorella standard culture (with a certain cell concentration). Chlorella vulgaris IPPAS С-66, IPPAS С-111 and IPPAS С-2019 strains served as object of research. Density of initial in vitro suspensions (after inoculation) was 0.9 mln cells/ml. Cultivation was carried out during 12 days on a Hoagland medium with a pH of 7 (temperature of 35∘C, illumination of 10 klx). Sample selection for analysis and measurement was carried out daily, three times per day. Based on the obtained data, readings of photoelectric colorimeter KFK-3.01 were calibrated via direct count of chlorella cells quantity in Goryaev’s chamber. Use of calibration curve made it possible to reduce significantly time and error in determination of cell number in suspension cultures. The proposed technique allows counting chlorella cells in the growth and development dynamics with sufficient accuracy, high sensitivity, reproducibility and speed. It can be used for comparative determination of the growth parameters of strains in vitro, standardization of suspension cultures, semi-quantitative determination of chlorella biomass in order to predict the yield of desired product
Analyzing Multi-Head Self-Attention: Specialized Heads Do the Heavy Lifting, the Rest Can Be Pruned
Multi-head self-attention is a key component of the Transformer, a
state-of-the-art architecture for neural machine translation. In this work we
evaluate the contribution made by individual attention heads in the encoder to
the overall performance of the model and analyze the roles played by them. We
find that the most important and confident heads play consistent and often
linguistically-interpretable roles. When pruning heads using a method based on
stochastic gates and a differentiable relaxation of the L0 penalty, we observe
that specialized heads are last to be pruned. Our novel pruning method removes
the vast majority of heads without seriously affecting performance. For
example, on the English-Russian WMT dataset, pruning 38 out of 48 encoder heads
results in a drop of only 0.15 BLEU.Comment: ACL 2019 (camera-ready
- …