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

The term 'developmental bias' promoted in the Special Issue of ‘Evolution & 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.

EXPERIMENTAL DETERMINATION OF ANISOTROPIC EMISSION OF NEUTRONS FROM 252CF NEUTRON SOURCE WITH THE SPHERICAL PROTECTION CASE

The anisotropic emission of neutrons from a cylindrical X1 252Cf source with the spherical external casing was experimentally determined. The influence of metal materials and shapes of the external casing to the anisotropy factor, FI(θ), was assessed by the Monte Carlo calculation, before performing the measurement. The results of the calculation implied that light- and spherical-shaped external casing decreases the anisotropic emission of neutrons from a cylindrical source and the nature of the material does not affect the anisotropic emission to a large extent. The experimental results obtained when a spherical-shaped aluminum protection case was employed also revealed that the anisotropy factor was close to 1.0 with a wide zenith angle range. Considering the source handling and measures against mechanical impact to the source, we designed an SUS304-made spherical protection case for a renovated source delivering apparatus. With the SUS304-made spherical protection case, the measured anisotropy factor FI(90) was determined to be 1.002 ± 0.002 (k = 1). Results from the experiments also indicated that the measured anisotropy factor has a flat distribution from 55 to 125° with zenith angle.

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

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.

EFFECTS OF STIFFNESS ON SHORT, SEMIFLEXIBLE HOMOPOLYMER CHAINS

Conformational and transition behavior of finite, semiflexible homopolymers is studied using an extension of the Wang–Landau algorithm. Generation of a flat distribution in the sampling parameters energy and stiffness allows for efficient investigation of transitions between various conformational phases. Of particular importance is the ability to predict behavior for a given stiffness value, where three classes of minimum energy conformations are expected: Solid-globular, rod-like and toroidal. We present first results highlighting the behavior of a single N = 20 length chain.

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

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.

METHOD OF ANALYTIC EVOLUTION OF FLAT DISTRIBUTION AMPLITUDES IN QCD

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.