scholarly journals Optimal updating magnitude in adaptive flat-distribution sampling

2017 ◽  
Vol 147 (17) ◽  
pp. 174105
Author(s):  
Cheng Zhang ◽  
Justin A. Drake ◽  
Jianpeng Ma ◽  
B. Montgomery Pettitt
Keyword(s):  
Flat Distribution

scholarly journals Jupiter's Radiation Belts and Upper Atmosphere

1974 ◽  
Vol 65 ◽  
pp. 375-383
Author(s):  
Joseph J. Degioanni ◽  
John R. Dickel
Keyword(s):  
Radio Emission ◽  
Radiation Belts ◽  
Upper Atmosphere ◽  
Mixing Ratio ◽  
Frequency Range ◽  
Emission Data ◽  
High Energies ◽  
Isotropic Distribution ◽  
Relativistic Particles ◽  
Flat Distribution

Models of Jupiter's radiation belts have been constructed to determine the distribution of particles and their energies which will produce the observed decimetric radio emission. Data on the spectrum and the variation of emission with Jovian longitude have been used to show that the relativistic particles have a nearly isotropic distribution with high energies (of order 100 MeV) within 2 Jovian radii and a very flat distribution in the equatorial plane of low energy particles further out in the magnetosphere.Subtraction of the emission predicted by this model from the total radio emission shows that the thermal contribution in the frequency range between 3000 and 10000 MHz is somewhat less than had been previously expected. (The brightness temperature of the planetary disk is 180 K at 3000 MHz, for example.) This suggests that the ammonia mixing ratio in Jupiter's upper atmosphere may be as high as 0.002.

scholarly journals Refracting into ultra-diffuse galaxy NGC 1052-DF2 by passing near the centre of NGC 1052

2020 ◽  
Vol 495 (1) ◽  
pp. L144-L148 ◽  
Author(s):  
Ran Huo
Keyword(s):  
Dark Matter ◽  
Physical Mechanism ◽  
Dwarf Galaxy ◽  
Recent Observation ◽  
Tidal Effect ◽  
Natural Consequence ◽  
Formation Theory ◽  
The Galaxy ◽  
Standard Structure ◽  
Flat Distribution

ABSTRACT The recent observation of the ultra-diffuse galaxy NGC 1052-DF2 shows a galaxy may lack dark matter, which becomes a challenge to the standard structure formation theory. Here, we show that such phenomena can be a natural consequence if the NGC 1052-DF2 had experienced a single passage within a few kpc to the centre of the galaxy NGC 1052. The tidal effect of NGC 1052 in the encounter will heat the NGC 1052-DF2, and stretch the previous dwarf galaxy significantly into its current size. The relative lack of dark matter in the observed region is a natural consequence of the dark matter limited total amount in the corresponding small central region before the encounter, together with a systematic underestimation of the trace mass estimator method during revirialization after the encounter. The observed flat distribution of the ultra-diffuse galaxy can be reproduced with a cored initial star profile, which is a major improvement compared with the previous work. Our results show no need for introducing any new physical mechanism, as well as an alternative origin of an ultra-diffuse galaxy without repeated pericentre passage.

scholarly journals Statistical Properties of an Unbiased Sample of F7-K Binaries: Towards The Long-Period Systems

2004 ◽  
Vol 191 ◽  
pp. 28-32 ◽  
Author(s):  
A. Eggenberger ◽  
J.-L. Halbwachs ◽  
S. Udry ◽  
M. Mayor
Keyword(s):  
Main Sequence ◽  
Equal Mass ◽  
Statistical Properties ◽  
Spectroscopic Binaries ◽  
Mass Ratio ◽  
Long Period ◽  
Period Distribution ◽  
Solar Type ◽  
Flat Distribution ◽  
Visual Binaries

AbstractWe have undertaken a new investigation of the statistical properties of main-sequence binaries, which is a revision and extension of the Duquennoy & Mayor survey of solar-type stars. The analysis has been divided into two parts: the spectroscopic binaries with periods shorter than 10 years, and the long-period systems including visual binaries and common proper motion pairs. In this contribution we present preliminary results regarding the intrinsic mass ratio and period distributions of visual binaries. Our results are strongly limited by small-number statistics, but when combined with the ones found for the spectroscopic binaries, the following results are obtained: (i) the excess of equal-mass binaries, if still present, is less important for long-period systems than for the binaries with P < 50 days; (ii) the period distribution is inconsistent with a flat distribution.

scholarly journals LOCALIZATION OF β-GALACTOSIDASES AND ACID PHOSPHATASE IN THE SMALL INTESTINAL WALL COMPARISON OF ADULT AND SUCKLING RAT

1969 ◽  
Vol 17 (5) ◽  
pp. 341-347 ◽  
Author(s):  
CHRISTER NORDSTRÖM ◽  
OTAKAR KOLDOVSKÝ ◽  
ARNE DAHLQVIST
Keyword(s):  
Acid Phosphatase ◽  
Intestinal Wall ◽  
Quantitative Comparison ◽  
Distribution Profile ◽  
Before And After ◽  
Fresh Frozen ◽  
Old Rats ◽  
Small Intestinal ◽  
Different Parts ◽  
Flat Distribution

By horizontal sectioning of fresh frozen pieces of rat intestinal wall different parts of the villi and crypts were isolated. The sections were collected in groups, homogenized and used for enzyme analyses. Single sections for histologic examination were taken before and after each collection. A quantitative comparison of the distribution of the two intestinal β-galactosidases, EC 3.2.1.23 (neutral and acid β-galactosidase), and the acid phosphatase, EC 3.1.3.2, in jejunum and ileum of adult and suckling (12 days old) rats was performed. The neutral β-galactosidase, which corresponds to the enzyme usually called lactase, was always present along the villi with the highest activities in the apical halves of the villi. This distribution profile is typical for digestion enzymes. The acid β-galactosidase, which is chiefly a heterogalactosidase, and acid phosphatase were found to have a rather flat distribution profile with about the same activities along the villi and in the crypts. The only exception was the ileum of suckling rat, in which especially the acid β-galactosidase showed higher activity in the villi and decreased toward the crypts. The results support the concept that the neutral β-galactosidase is responsible for the digestion of dietary lactose, while the acid β-galactosidase seems to have a different functional significance. That this enzyme is distributed in parallel with the acid phosphatase is consistent with the suggestion that the acid β-galactosidase may be a lysosomal enzyme.

scholarly journals Why is the term 'developmental bias' misleading? (full version)

2020 ◽  
Author(s):  
Andrzej Gecow
Keyword(s):  
Natural Selection ◽  
Time Interval ◽  
Special Issue ◽  
Independent Source ◽  
Full Version ◽  
Broad Term ◽  
Developmental Parameters ◽  
Random Variability ◽  
Flat Distribution ◽  
The Way

The term 'developmental bias' promoted in the Special Issue of ‘Evolution &amp; Development’ was initially defined as the effect in evolution direction creating by correlation of changed developmental parameters. The understanding of the term is in the Special Issue much broader and very poorly defined. Promoting such a broad term related to observation makes difficult to explain specific mechanisms. It is now time for the task of explaining to become more important in biology than just collecting facts. The term requires quick organization and division into many different concepts. I suggest replacing this term with a shorter one (devbias) with an additional tip indicating a specific variant according to the proposed ordering system. Mainly the mechanisms giving variability clearly focused on greater fitness (devbiases4) have been added. Devbias4 was treated in Special Issue as an independent source of adaptation supporting natural selection. Focusing on the time interval of current evolution, where collected devbiases4 indeed supports natural selection, it is usually forgotten to stress that they are also the result of previous natural selection and only mediate the transmission of its effects. This leads to a dangerous message beyond biology that scientific observations have shown that the Darwinian mechanism is not the only source of adaptation. By the way of ordering ‘devbias’ the understanding of ‘randomness’ is discussed to show differences between ‘flat distribution’, ‘variation blind on needs’ and ‘real random variability’ which in Special Issue are typically mixed.

scholarly journals Distribution of refractory and volatile elements in CoRoT planet host stars

2009 ◽  
Vol 5 (S265) ◽  
pp. 424-425
Author(s):  
C. Chavero ◽  
R. de la Reza ◽  
R. C. Domingos ◽  
N. A. Drake ◽  
C. B. Pereira ◽  
...  
Keyword(s):  
Internal Migration ◽  
Spectroscopic Determination ◽  
Atmospheric Parameters ◽  
Chemical Abundances ◽  
Volatile Elements ◽  
Preliminary Results ◽  
Transiting Planets ◽  
Host Stars ◽  
Flat Distribution

AbstractWe report on preliminary results of spectroscopic determination of the atmospheric parameters and chemical abundances of the parent stars of the recently discovered transiting planets CoRoT-2b and CoRoT-4b. We found a flat distribution of the relative abundances as a function of their condensation temperatures. Also, we introduce a new methodology to investigate a relation between the abundances of these stars and the internal migration of their planets.

scholarly journals Duplicity Among Solar-Type Stars

1992 ◽  
Vol 135 ◽  
pp. 82-88 ◽  
Author(s):  
Helmut A. Abt ◽  
Daryl W. Willmarth
Keyword(s):  
Open Clusters ◽  
Radial Velocities ◽  
Apparent Magnitude ◽  
Limited Sample ◽  
Visual Systems ◽  
Binary Formation ◽  
Capture Mechanism ◽  
Solar Type ◽  
Flat Distribution

AbstractFrom a new study of 113 F8-G1 IV or V primaries in an apparent-magnitude limited sample, measured with a CCD for about 20 radial velocities of accuracy 0.2-0.5 km s−1 each, we collected data for 28 binary orbits and 39 visual systems. We again found a flat distribution (or slightly decreasing toward lower masses) of secondary masses, unlike the Salpeter distribution for B2-B5 stars. But we find that the different distributions for these field stars and for open clusters of various ages can all be explained by a capture mechanism of binary formation.

Numerical Study of Fluid Mixing in a Microchannel with a Circular Chamber on a Rotating Disk

2012 ◽  
Vol 542-543 ◽  
pp. 1113-1119 ◽  
Author(s):  
Huan Chao Chiu ◽  
Jerry M Chen
Keyword(s):  
Rotational Speed ◽  
Numerical Study ◽  
Rotating Disk ◽  
Transverse Flow ◽  
Fluid Mixing ◽  
Mixing Efficiency ◽  
Straight Channel ◽  
Lower Range ◽  
Speed Range ◽  
Flat Distribution

This paper reports numerical simulations of fluid mixing in a rotating microchannel with a microchamber fabricated on a CD-like substrate. The sample fluids are driven by the centrifugal force and brought in contact at a Y-shaped junction, and then the mixing flow moves through a straight channel with a circular chamber where the main course of mixing takes place. The CD-like micromixer is rotated clockwise at speeds ranging from 300 to1200 rpm. With increasing rotational speed, the mixing efficiency is found dropping in the lower range (≤ 540 rpm), where the diffusion still dominates the mixing, and then grows progressively to reach as much as 90%. The progressively growth in the higher speed range significantly improves the slightly descending and flat distribution for a straight mixing channel without a circular chamber. This significant enhancement of mixing is due mainly to the vortices generated in the circular chamber and the strong transverse flow induced by the Coriolis force.

scholarly journals METHOD OF ANALYTIC EVOLUTION OF FLAT DISTRIBUTION AMPLITUDES IN QCD

2011 ◽  
Vol 04 ◽  
pp. 227-238 ◽  
Author(s):  
ASLI TANDOGAN ◽  
ANATOLY V. RADYUSHKIN
Keyword(s):  
Standard Method ◽  
Analytical Method ◽  
Gegenbauer Polynomials ◽  
End Points ◽  
Good Convergence ◽  
Evolution Parameter ◽  
Flat Distribution

A new analytical method of performing ERBL evolution is described. The main goal is to develop an approach that works for distribution amplitudes that do not vanish at the end points, for which the standard method of expansion in Gegenbauer polynomials is inefficient. Two cases of the initial DA are considered: a purely flat DA, given by the same constant for all x, and an antisymmetric DA given by opposite constants for x ≷ 1/2. For a purely flat DA, the evolution is governed by an overall [Formula: see text] dependence on the evolution parameter t times a factor that was calculated as an expansion in t. For an antisymmetric flat DA, an extra overall factor |1 - 2x|2t appears due to a jump at x = 1/2. A good convergence was observed in the t ≲ 1/2 region. For larger t, one can use the standard method of the Gegenbauer expansion.

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