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The COVID-19 pandemic has brought significant changes in managing of patients with rheumatoid arthritis. Rituximab-treated patients were more susceptible to severe infection. This required a "switch" to another genetically engineered drug in the patients with high risk of adverse COVID-19. In this study, we assessed the severity of immune response to SARS-CoV-2 antigens in rituximab-treated patients with rheumatoid arthritis vaccinated with the combined vector vaccine Gam-COVID-Vac. Insufficient formation of the humoral response and a high level of T-cell response to SARS-CoV-2 antigens in this group of patients were revealed. An imbalance of cellular and humoral response may play a role in more severe COVID-19 in rituximab-treated patients with rheumatoid arthritis. [ABSTRACT FROM AUTHOR]

A new human uveal melanoma (UM) cell line uMel1 was established by mechanical disintegration of a tumor fragment. uMel1 cells had a stellate dendrite-like shape, contained a lot of brown melanin pigment, and had a low mitotic index. Optimization of cultivation conditions led to an increase in the rate of cell proliferation and was accompanied by the loss of brown pigment. Since the melanin precursor is L-dihydroxyphenylalanine (L-DOPA), the authors analyzed the cultivation of uMel1 cells in the presence of L-DOPA. When L-DOPA was used at a concentration of 20 μg/mL, causing a decrease in cell viability by no more than 10%, melanocytes uMel1 synthesized melanin. It can be concluded that cultivation in the presence of L-DOPA provides the phenotype of melanin-containing melanocytes of uMel1 personal culture under conditions of long-term cultivation. Analysis of cell adhesion molecules N-cadherin (N-cad), E-cadherin (E-cad), and Mel-CAM, as well as receptors of the epidermal growth factor (ErbB) family by flow cytometry, showed that uMel1 cells have a phenotype of N-cad–/E-cad–/Mel-CAM+/HER2low/HER3low, and can be used for the study of targeted drugs to Mel-CAM, HER2 and HER3. [ABSTRACT FROM AUTHOR]

The production of proteins capable of binding ice is one of the strategies evolved in biological organisms for survival in cold ecosystems where there is a risk of freezing. These proteins have an important ability to bind to the surface of ice, influence its growth and prevent cell damage and death. To understand the nature of interaction of such proteins with ice, it is necessary to know their structure. This study contributes to the understanding of the structural and dynamic mechanisms of action of ice-binding proteins that ensure the adaptation of organisms in critical conditions. The study of the contribution of proteins capable of binding ice to adaptation to cold conditions opens up wide opportunities in solving a number of important medical problems, including the development of effective cellular and organ cryoprotectants, as well as long-term storage of food products without loss of their consumer properties in the food industry. [ABSTRACT FROM AUTHOR]

Abstract—Superbubbles driven by supernovae explosions are sometimes considered as a source of triggering star formation. Using three dimensional simulations we consider the dynamics and stability of a gas layer between interacting bubbles of different age located in the galaxy disk midplane. It is shown that the lifetime of a dense gas layer increases for the interacting bubbles formed by supernovae explosions when the separation between the clusters is larger than the scale height of the disc. In case of interacting young bubbles a dense "wall" between them is rapidly destroyed by shock waves coming from hot interiors. It was found that dense gas "survives" at the edges of the interacting layer and its mass gradually increases. The possibility of star formation at the edges of the layer is discussed and compared with observations of star formation regions in nearby dwarf galaxies. [ABSTRACT FROM AUTHOR]

A pulse-periodic cesium discharge is studied in a wide range of its parameters in two lamps with burners of the same diameter (5 mm), but with different interelectrode spacings (55 and 22 mm). It is found that such a decrease in the length of the plasma column leads to a significant change in the properties of the discharge. In the longer burner, contraction of the discharge column occurs as the pressure increases with the localization of the plasma column at the wall of the discharge tube, and a significant increase in lamp efficacy is observed with a further increase in pressure. In the shorter burner, contraction occurs at lower pressures (specific powers) with the localization of the plasma column along the tube axis, and there is no increase in lamp efficacy with a subsequent increase in pressure. [ABSTRACT FROM AUTHOR]

Determination of the coal-strength coefficient in accordance with State Standard GOST 21153.1–75 is clear and simple. No complex equipment is required, and capital expenditures and energy costs are relatively low. This method satisfactorily reproduces the crushing conditions of coal in hammer systems, and the granulometric composition of the ground sample is close to industrial values. The relations of the composition, structure, and properties of coal from Ukraine, Russia, the United States, and Kazakhstan with the Protod'yakonov strength coefficient are investigated. It is shown that the Protod'yakonov strength coefficient decreases with increase in the vitrinite reflection coefficient, the carbon content, and the Hardgrove grindability index and also with decrease in volatile matter, the oxygen content, and the mean diameter of the coal particles. The derived mathematical formulas permit prediction of the Protod'yakonov strength coefficient with satisfactory accuracy on the basis of the carbon content, the oxygen content, volatile matter, the vitrinite reflection coefficient, the mean particle diameter, and the Hardgrove grindability of the coal. [ABSTRACT FROM AUTHOR]

The paper analyzes the main criteria for the limit state of structural materials at the stage of macrocrack nucleation, which are based on the basic provisions of thermodynamics of irreversible processes in continuum mechanics of damageability. The limits of their application for the case of complex stressed state are established. A model of scattered damage accumulation depending on the level of irreversible strain is presented and the dependences of kinetics parameters of damage accumulation and damage limit value on the elastic-plastic characteristics of the material under pure tension conditions are established. The kinetics of damage accumulation according to the presented model is compared to the experimental values for several of structural materials. The methodology of the basic experiment with cylindrical solid specimens is described, taking into account the non-uniformity of the strain distribution along the specimen radius. The results of damage accumulation by shear failure mechanism obtained via the developed technique are compared with the experimental results of thin-walled specimens. It is shown that the value of damageability parameter essentially depends on the type of stressed state. On the basis of Davidenkov–Fridman approach, which takes into account two (tear and shear) failure mechanisms, a generalized phenomenological criterion of limiting state is proposed and substantiated using the Nadai–Lode stress state type parameter. [ABSTRACT FROM AUTHOR]

The Hardgrove grindability index HGI of binary coal blends is determined. The blends contain coal of different metamorphic development in different proportions. Mathematical formulas permit prediction of HGI for a coal blend on the basis of the grinding indices for its individual components. For a binary coal blend with separate preparation of the components, HGI is found to exceed the calculated value (by 3.6, on average). For a blend with integrated preparation of the components, it is less than the calculated value (by 3.6, on average). Crushing of the whole batch is found to require more energy than differential crushing of the batch components. [ABSTRACT FROM AUTHOR]

The differences in the relationships between the physical parameters and the chemical-element abundances in accreted globular star clusters and those formed inside the Galaxy have been investigated. The information on the supposed formation sites of the clusters based on the Gaia DR2 data is borrowed from the literature. Those sources estimate the probability of belonging to the Galactic bulge and disk, as well as to six known events of the merger of dwarf satellite galaxies with the Milky Way, for 151 globular clusters. Orbital elements, initial masses, population types, and ages are taken from the literature; the data on the chemical composition for 69 globular clusters of the Galaxy are taken from the authors' compiled catalog. It is shown that all metal-poor () genetically related globular clusters have high relative abundances of ‑elements. According to modern views, since type II supernovae release more -elements into the interstellar medium with increasing mass, it has been suggested that masses of type II supernovae in the Galaxy were greater than in the accreted galaxies. It is proved that the clusters of the low-energy group, which were considered accreted, are genetically related to a single protogalactic cloud, same as the unstratified clusters UKS 1 and Liller 1, which most likely belong to the bulge. It is shown that not only the lower but also the upper limits of the clusters' masses decrease with an increase in the average radius of their orbits. The latter fact is explained by a decrease in the masses of emerging clusters with a decrease in the masses of their host galaxies. It is demonstrated that an extremely multicomponent stellar population is observed only in accreted globular clusters with an initial mass >106 . It has been suggested that these clusters retained all the matter ejected by their evolved stars, from which new generations of stars formed due to long evolution far from our Galaxy. [ABSTRACT FROM AUTHOR]

We use the data of our extended catalog of spectroscopic determinations of elemental abundances in the atmospheres of Galactic-field RR Lyrae type variables to show that metal-rich RR Lyraes ([Fe/H] > −1.0) have anomalous abundances of some elements. In particular, the relative abundances of scandium, titanium, and yttrium in metal-rich RR Lyrae type variables are lower than the corresponding abundances in field stars of similar metallicity beyond the errors. We discuss the errors of the determination of the abundances of the above elements and point out the fact that no europium, zirconium, and lanthanum abundance determinations are available for metal-rich RR Lyrae type variables. We also analyze various possible causes of the observed peculiarities of the chemical composition of metal-rich RR Lyrae type variables. [ABSTRACT FROM AUTHOR]

Abstract—Using modern published data on velocities and spectroscopic definitions of chemical elements in stellar objects of the Galaxy, we investigated the relationship of chemical composition with the kinematics of different populations. The paper shows that the old stellar populations of the Galaxy, belonging (by the kinematic criterion) to the thick disk subsystem—globular clusters, field variables of the type RR Lyrae (lyrids), as well as close F– G dwarfs and field giants, have different chemical composition. In particular, the dwarfs and giants of the field are on average more metallic than the globular clusters and lyrids of the field. Moreover, the relative abundances of α-elements in the range [Fe/H] > −1.0 are the highest for globular clusters, and are the lowest for field variables of the RR Lyrae type. Based on the analysis of the nature of the dependences of [α/Fe] on [Fe/H] for these objects it was suggested that the thick disk subsystem in the Galaxy is composite and at least three components exist independently within it. The oldest one includes metal-rich globular clusters that formed from a single proto-galactic cloud shortly after the start of type Ia supernovae outbursts. Then the subsystem of field stars of a thick disk was formed as a result of "heating" of stars of already formed thin disk of the Galaxy by a rather massive dwarf satellite galaxy that fell on it. And finally, subsystems of field stars with the kinematics of not only a thick, but even a thin disk that fell on the Galaxy from this captured satellite galaxy. [ABSTRACT FROM AUTHOR]

Based on published parameters of their atmospheres, the masses of 100 RR Lyrae variables (lyrids) in the field are determined using evolutionary tracks from the Dartmouth data base and the properties of lyrids with different metallicities are compared. It was found that the masses of the metal-rich ([Fe/H] > –0.5) lyrids with thin-disk kinematics lie within an interval of (0.51-0.60) Mʘ. According to modern concepts, the initial masses of these stars should be no more than (0.7-0.8) Mʘ. The long evolution time of these low-mass stars conflicts with the significantly lower age of even the oldest stars in the thin-disk subsystem of the Galaxy. A possible explanation is proposed for the nature of these comparatively young and metal-rich variables. [ABSTRACT FROM AUTHOR]

The geometrical structure and energy characteristics of various isomeric forms of cationic spiropyrans were investigated by quantum-chemical approach depending on substituents arrangement in 2H-chromene moiety. The energetically preferred structures for stabilization during isomerization process were identified. [ABSTRACT FROM AUTHOR]

A comprehensive statistical analysis of the relationship between the chemical and spatially kinematic parameters of the globular clusters of the Galaxy has been performed. The data of the author's compilation catalog contain astrophysical parameters for 157 clusters and the relative abundances of α-elements for 69 clusters. For 121 clusters, the data are supplemented by spatially kinematic parameters taken from the literature. The phenomenon of reddening of horizontal branches of low-metal accreted globular clusters is discussed. We consider the contradiction between the criteria for clusters to belong to the subsystems of the thick disk and the halo in terms of chemical and kinematic properties. It consists in the fact that, regardless of belonging to the galactic subsystems by kinematics, almost all metallic ([Fe/H] >–1.0) clusters are located close to the center and plane of the Galaxy, while among the less metallic of both subsystems there are many distant ones. Differences in the abundances of α-elements in the stellar objects of the Galaxy and the surrounding low-mass dwarf satellite galaxies confirm the well-known conclusion that all globular clusters and field stars of the accreted halo are remnants of galaxies of higher mass than the current environment of the Galaxy. A possible exception is a distant low-metal cluster with low relative abundance of α-elements Rup 106. [ABSTRACT FROM AUTHOR]

Published data from 25 papers published between 1995 and 2017 are used to find the effective temperatures and surface acceleration of gravity for 100 RR Lyrae variables in the galactic field with known chemical composition. The atmospheric parameters of almost half the stars in our list were determined in two or more papers. The mean-weighted values of the parameters are calculated for these stars. The values of Teff and logg for almost all the stars studied here lie within the theoretically calculated range where highly evolved stars turn out to be variable. The convergence of the various determinations of the corresponding parameters is analyzed. It is concluded that the values of the effective temperatures and acceleration of gravity for these RR Lyrae variables are highly reliable. [ABSTRACT FROM AUTHOR]

A catalog of Galactic globular clusters has been compiled and used to analyze relations between the chemical and kinematic parameters of the clusters. The catalog contains positions, distances, luminosities, metallicites, and horizontal-branch morphology indices for 157 globular clusters, as well as space velocities for 72 globular clusters. For 69 globular clusters, these data are suppleented with the relative abundances of 28 chemical elements produced in various nuclear-synthesis processes, taken from 101 papers published between 1986 and 2018. The tendency for redder horizontal branches in lowmetallicity accreted globular clusters is discussed. The discrepancy between the criteria for cluster membership in the thick-disk and halo subsystems based on chemical and kinematic properties is considered. This is manifest through the fact that all metal-rich ([Fe/H] > −1.0) clusters are located close to the center and plane of the Galaxy, regardless of their kinematic membership in particular Galaxy subsystems. An exception is three accreted clusters lost by a dwarf galaxy in Sagittarius. At the same time, the fraction of more distant clusters is high among metal-poorer clusters in any kinematically selected Galactic subsystem. In addition, all metal-rich clusters whose origins are related to the same protogalactic cloud are located in the [Fe/H]–[α/Fe] diagram considerably higher than the strip populated with field stars. All metal-poor clusters (most of them accreted) populate the entire width of the strip formed by high-velocity (i.e., presumably accreted) field stars. Stars of dwarf satellite galaxies (all of them being metal-poor) are located in this diagram much lower than accreted field stars. These facts suggest that all stellar objects in the accreted halo are remnants of galaxies with higher masses than those in the current environment of the Galaxy. Differences in the relative abundances of α-process elements among stellar objects of the Galaxy and surrounding dwarf satellite galaxies confirmthat the latter have left no appreciable stellar traces in the Galaxy, with the possible exception of the low-metallicity cluster Rup 106, which has low relative abundances of α-process elements. [ABSTRACT FROM AUTHOR]

The reaction of Finland trityl with tertiary aliphatic alcohols containing a terminal tertiary amino group, followed by quaternization of the amino groups, afforded new highly polar tri- and hexacationic derivatives. The obtained compounds are characterized by a sharp singlet signal in the EPR spectrum and are soluble in water over a wide pH range. [ABSTRACT FROM AUTHOR]

The surface gravities and effective temperatures have been added to a compilative catalog published earlier, which includes the relative abundances of several chemical elements for 100 field RR Lyrae stars. These atmoshperic parameters and evolutionary tracks from the Dartmouth database are used to determine the masses of the stars and perform a comparative analysis of the properties of RR Lyrae stars with different chemical compositions. The masses of metal-rich ([Fe/H] > −0.5) RR Lyrae stars with thin disk kinematics are in the range (0.51−0.60)M⊙. Only stars with initial masses exceeding 1M⊙ can reach the horizontal branch during the lifetime of this subsystem. To become an RR Lyrae variable, a star must have lost approximately half of its mass during the red-giant phase. The appearance of such young, metal-rich RR Lyrae stars is possibly due to high initial helium abundances of their progenitors. According to the Dartmouth evolutionary tracks for Y = 0.4, a star with an initial mass as low as 0.8 M⊙ could evolve to become an RR Lyrae variable during this time. Such stars should have lost (0.2−0.3)M⊙ in the red-giant phase, which seems quite realistic. Populations of red giants and RR Lyrae stars with such high helium abundances have already been discovered in the bulge; some of these could easily be transported to the solar neighborhood as a consequence of perturbations due to inhomogeneities of the Galaxy's gravitational potential. [ABSTRACT FROM AUTHOR]

The correlations of the composition, structure, and properties of coal from Ukraine, Russia, Canada, Australia, the Czech Republic, Poland, and Indonesia with its Hardgrove grindability index are investigated. It is found that the Hardgrove grindability increases with increase in total carbon content Cdaf and aromatic carbon content Car, as well as the unsaturation δ of the structure. Correspondingly, the Hardgrove grindability decreases with increase in the volatile matter and decrease in the vitrinite reflection coefficient due to increase in the aliphatic carbon content and also with decrease in unsaturation of the coal's organic mass. The Hardgrove grindability is calculated for unoxidized (reduced) coking coal of different types (corresponding to Ukrainian State Standard DSTU 3472:2015). [ABSTRACT FROM AUTHOR]

Abstract: The experimental results are presented for a laser-induced modification of the structure of porous glass (PG) preliminarily doped with an aqueous nitric-acid solution of Bi(NO3)3. It is established that the laser-induced local stabilization of bismuth active centers (BACs) in the bulk of PG plates is possible, which is confirmed by the change in the luminescence in the irradiation zone. [ABSTRACT FROM AUTHOR]

A catalog of the chemical and spatial-kinematic parameters of 415 RR Lyrae variables (Lyrids) in the galactic field is compiled. Spectroscopic determinations of the relative abundances of 13 chemical elements in 101 of the RR Lyrae variables are collected from 25 papers published between 1995 and 2017. The data from different sources are reduced to a single solar abundance scale. The mean weighted chemical abundances are calculated with coefficients inversely proportional to the reported errors. An analysis of the deviations in the published relative abundances in each star from the mean square values calculated from them reveals an absence of systematic biases among the results from the various articles. The rectangular coordinates of 407 of the RR Lyrae variables and the components of the three-dimensional (3D) velocities of 401 of the stars are calculated using data from several sources. The collected data on the abundances of chemical elements produced by various nuclear fusion processes for the RR Lyrae variables of the field, as well as the calculated 3D velocities, can be used for studying the evolution of the Galaxy. [ABSTRACT FROM AUTHOR]

Data of our compiled catalog containing the positions, velocities, and metallicities of 415 RR Lyrae variable stars and the relative abundances [el/Fe] of 12 elements for 101 RR Lyrae stars, including four α elements (Mg, Ca, Si, and Ti), are used to study the relationships between the chemical and spatial-kinematic properties of these stars. In general, the dependences of the relative abundances of a elements on metallicity and velocity for the RR Lyrae stars are approximately the same as those for field dwarfs. Despite the usual claim that these stars are old, among them are representatives of the thin disk, which is the youngest subsystem of the Galaxy. Attention is called to the problem of lowmetallicity RR Lyrae stars. Most RR Lyrae stars that have the kinematic properties of thick disk stars have metallicities [Fe/H] < -1.0 and high ratios [α/Fe] ≈0.4, whereas only about 10% of field dwarfs belonging to the so-called "low-metallicity tail" have this chemical composition. At the same time, there is a sharp change in [α/Fe] in RR Lyrae stars belonging just to the thick disk, providing evidence for a long period of formation of this subsystem. The chemical compositions of SDSS J1707+58, V455 Oph, MACHO176.18833.411, V456 Ser, and BPSCS 30339-046 do not correspond to their kinematics. While the first three of these stars belong to the halo, according to their kinematics, the last two belong to the thick disk. It is proposed that they are all most likely extragalactic, but the possible appearance of some of them in the solar neighborhood as a result of the gravitational action of the bar on field stars cannot be ruled out. [ABSTRACT FROM AUTHOR]

Based on our compiled catalogue of positions, velocities, ages, and abundances of nine chemical elements for 221 classical Cepheids, we analyze the dependences of the relative abundances of α-elements as well as rapid and slow neutron capture elements on metallicity, space velocity components, and Galactocentric distance. We have found that the relative abundances of all elements in Cepheids do not depend on velocity but increase with Galactocentric distance and decrease with increasing metallicity, just as in thin-disk dwarfs and giants. In Cepheids, however, the [ α/Fe]-[Fe/H] relation lies below, while the [ r/Fe]-[Fe/H] and [ s/Fe]-[Fe/H] relations lie above the analogous sequences for dwarfs and giants. We hypothesize that upon reaching a nearly solar metallicity in the interstellar medium of the thin disk, the most massive stars ceased to explode as type II supernovae, which mostly enriched the interstellar medium with α-elements. As a result, an underabundance of α-elements and a slight overabundance of r-process elements, which are ejected into the interstellar medium by less massive (8–10 M⊙) type II supernovae, were formed in the next generations of stars. The overabundance of s-process elements in Cepheids can be explained by the fact that some of the s-elements were produced in the weak s-process in the interiors of massive stars, which may be able to eject the upper parts of their envelopes even without any explosion like asymptotic giant branch stars. And since such massive stars, exploding as type II supernovae, also enriched the interstellar medium with a considerable amount of iron atoms, the [ s/Fe] ratios (along with [ r/Fe]) in the next generations of stars must be higher in their absence. [ABSTRACT FROM AUTHOR]

Results of investigations of E. coli DNA glycosylases using pre-steady-state kinetics are considered. Special attention is given to the connection of conformational changes in the interacting biomolecules with kinetic mechanisms of the enzymatic processes. [ABSTRACT FROM AUTHOR]

Data from the revised Geneva-Copenhagen catalog are used to study the influence of radial migration of stars on the age dependences of parameters of the velocity ellipsoids for nearby stars in the thin disk of the Galaxy, assuming that the mean radii of the stellar orbits remain constant. It is demonstrated that precisely the radial migration of stars, together with the negative metallicity gradient in the thin disk, are responsible for the observed negative correlation between the metallicities and angular momenta of nearby stars, while the angular momenta of stars that were born at the same Galactocentric distances do not depend on either age or metallicity. The velocity components of the Sun relative to the Local Standard of Rest derived using data for stars born at the solar Galactocentric distance are ( U⊙, V⊙, W⊙) LSR = (5.1 ± 0.4, 7.9 ± 0.5, 7.7 ± 0.2) km/s. The two coordinates of the apex of the solar motion remain equal to 〈 l⊙〉 = 70° ± 7° and 〈 b⊙〉 = 41° ± 2°, within the errors. The indices for the power-law age dependences of them ajor, middle, and minor semi-axes become 0.26±0.04, 0.32±0.03, and 0.07±0.03, respectively. As a result, with age, the velocity ellipsoid for thin-disk stars born at the solar Galactocentric distance increases only in the plane of the disk, remaining virtually constant in the perpendicular direction. Its shape remains far from equilibrium, and the direction of the major axis does not change with age: the ellipsoid vertex deviation remains constant and equal to zero within the errors (〈 L〉 = 0.7° ± 0.6°, 〈 B〉 = 1.9° ± 1.1°). Such a small increase in the velocity dispersion perpendicular to the Galactic plane with age can probably be explained by “heating” of the stellar system purely by spiral density waves, without a contribution from giant molecular clouds. [ABSTRACT FROM AUTHOR]

The scheme of a plasma-beam superheterodyne free-electron laser (PBSFEL) with H-ubitron pumping is analyzed and several possible variants of its practical implementation are considered. Some variants represent sources of highly monochromatic signals, while the other generate signals with a rather broad spectrum. The increment of wave growth in PBSFELs is estimated and it is established that, under otherwise equal conditions, these FELs are characterized by much greater gain increments than the equivalent two-stream devices. The proposed PBSFELs have good prospects as sources of high-power electromagnetic radiation in the millimeter wavelength range. [ABSTRACT FROM AUTHOR]

Quantitative characteristics of thermodynamic and kinetic cooperativity arising in the process of photomodification of a single-stranded DNA fragment with binary systems of oligonucleotide conjugates forming an active site on the target were studied. Oligonucleotides of the binary system were complementary to adjacent segments of the DNA target, and contained arylazide (X) and perylene (S) residues covalently attached to their terminal phosphates. Upon irradiation at the perylene absorption wavelength, the target was modified by the arylazide residue, which was activated owing to the contiguity with the sensitizing perylene group in the tandem complex. Basing on the kinetic data, the constants of association of both derivatives of oligonucleotides with the target were determined: Kx = 1.13 · 106 M–1, Ks = 1.49 · 104 M–1. It was determined that association of both oligonucleotides with the target proceeded with a positive cooperativity characterized by parameter α = 45. The kinetic cooperativity parameter β was found to be approximately equal to 200; this characterized the acceleration of target modification in complex with the binary reagent versus that in the absence of sensitizer. [ABSTRACT FROM AUTHOR]

The microwave radiation reflection coefficient of pure vanadium dioxide and its compositions with dielectrics exhibits a jumplike change upon a sample transition from dielectric into metallic state. The reflection coefficient may either increase or decrease, the sign and magnitude of the effect depending on the electromagnetic field frequency and the sample thickness. The phenomenon is explained by changes in the wave interference conditions upon the phase transition. [ABSTRACT FROM AUTHOR]

Several errors concerning the single star V455 Oph have been discovered in the study [1], which, however, do not affect the main conclusions of that study. V455 Oph was mistakenly ascribed the elemental composition of a different star. The spectroscopic elemental abundances of the RR Lyrae star V455 Oph were not determined, making it necessary to use the photometric abundance [Fe/H] = −1.42, and not +0.19, as was indicated in the published paper and in the on-line catalog; any reference to the star should be removed from the abstract and text of the paper. The authors apologize for these errors. In particular, the following text should be removed from Section 3 (p. 56): “However, RR Lyrae stars with the kinematics of the accreted halo also include some very metals-rich objects. For example, V455 Oph”… to the end of that paragraph. The second-to-last paragraph of Section 5, beginning “We also consider the chemical composition of V455 Oph to be unique”… should be removed in its entirety. Finally, the points ascribed to V455 Oph in Figs. 1e, 1f, Figs. 2a-2d, and Figs. 3a-3d should be considered erroneous. [ABSTRACT FROM AUTHOR]