Hydrogen atom moving across a strong magnetic field: analytical approximations

Analytical approximations are constructed for binding energies, quantum-mechanical sizes and oscillator strengths of main radiative transitions of hydrogen atoms arbitrarily moving in magnetic fields 10^{12}-10^{13} G. Examples of using the obtained approximations for determination of maximum transverse velocity of an atom and for evaluation of absorption spectra in magnetic neutron star atmospheres are presented.Comment: 17 pages, 3 figures, 5 tables, LaTeX with IOP style files (included). In v.2, Fig.1 and Table 5 have been corrected. In v.3, a misprint in the fit for oscillator strengths, Eq.(21), has been correcte

N-Electron Giant Dipole States in Crossed Electric and Magnetic Fields

Multi-electron giant dipole resonances of atoms in crossed electric and magnetic fields are investigated. Stationary configurations corresponding to a highly symmetric arrangement of the electrons on a decentered circle are derived, and a normal-mode and stability analysis are performed. A classification of the various modes, which are dominated by the magnetic field or the Coulomb interactions, is provided. Based on the MCTDH approach, we carry out a six-dimensional wave-packet dynamical study for the two-electron resonances, yielding in particular lifetimes of more than 0.1 $\mu$s for strong electric fields.Comment: 37 pages, 22 figs. (plus subfigures

Role of the Nuclear and Electromagnetic Interactions in the Coherent Dissociation of the Relativistic 7^7Li Nucleus into the 3^3H + 4^4He Channel

The differential cross section in the transverse momentum $Q$ and a total cross section of $(31\pm4)$ mb for the coherent dissociation of a 3-A-GeV/$c$ $^7$Li nucleus through the $^3$H$+^4$He channel have been measured on emulsion nuclei. The observed $Q$ dependence of the cross section is explained by the predominant supposition of the nuclear diffraction patterns on light (C, N, O) and heavy (Br, Ag) emulsion nuclei. The contributions to the cross section from nuclear diffraction ($Q\le400$ MeV/$c$) and Coulomb $(Q\le50$ MeV/$c$) dissociations are calculated to be 40.7 and 4 mb, respectively.Comment: ISSN 0021-3640, Pleiades Publishing, Ltd., 200

Photoionization of hydrogen in atmospheres of magnetic neutron stars

The strong magnetic fields (B ~ 10^{12} - 10^{13} G) characteristic of neutron stars make all the properties of an atom strongly dependent on the transverse component K_\perp of its generalized momentum. In particular, the photoionization process is modified substantially: (i) threshold energies are decreased as compared with those for an atom at rest, (ii) cross section values are changed significantly, and (iii) selection rules valid for atoms at rest are violated by the motion so that new photoionization channels become allowed. To calculate the photoionization cross sections, we, for the first time, employ exact numerical treatment of both initial and final atomic states. This enables us to take into account the quasi-bound (autoionizing) atomic states as well as coupling of different ionization channels. We extend the previous consideration, restricted to the so-called centered states corresponding to relatively small values of K_\perp, to arbitrary states of atomic motion. We fold the cross sections with the thermal distribution of atoms over K. For typical temperatures of neutron star atmospheres, the averaged cross sections differ substantially from those of atoms at rest. In particular, the photoionization edges are strongly broadened by the thermal motion of atoms; this "magnetic broadening" exceeds the usual Doppler broadening by orders of magnitude. The decentered states of the atoms give rise to the low-energy component of the photoionization cross section. This new component grows significantly with increasing temperature above 10^{5.5} K and decreasing density below 1 g/cm^3, i.e., for the conditions expected in atmospheres of middle-aged neutron stars.Comment: 19 pages including 8 figures, LaTeX (using aas2pp4.sty and epsf.sty). Accepted for publication in ApJ. PostScript available also at http://www.ioffe.rssi.ru/dtastrop.htm

Методические аспекты биологической оценки инсектоакарицидов на цветочных культурах защищённого грунта

Relevance. Analysis of the present range of pesticides that are used in flower orangeries showed critical shortage of allowed pesticides. Now there are no methods for registration testing of insecticides designed to protect flowers in greenhouses. Thus, the purpose of our research is to develop methodological approaches to assessment of abundance of major pests for flower cultures of protected ground and determination of biological effectiveness of new insectoacaricides.Methods. The following phytophages represent flower pests that are predominant in the protected ground: aphids: green peach – Myzus persicae Sulz., melon and cotton – Aphis gossypii Glov., greenhouse-potato – Aulacorthum solani Kalt., potato – Macrosiphum euphorbiae Thom., green rose – Macrosiphum rosae Linn.; whiteflies: greenhouse whitefly – Trialeurodes vaporariorum Wstw., silverleaf whitefly – Bemisia tabaci Genn.; thrips: tobacco – Thrips tabaci Lind., rose – Th. fuscipennis Hal., western flower – Frankliniella occidentalis Perg., heterophagous – F. intonsa Tryb., greenhouse – Heliothrips haemorrhoidalis Bouche; mites: red spider – Tetranychus urticae Koch.; red greenhouse – T. cinnabarinus BoisdResults. Researches related to assessment of abundance of major pests for flower cultures and choosing methods related to determination of biological effectiveness of insectoacaricides were performed in flower orangeries of Leningrad Region on hybrid tea roses Rosa L., chrysnatemums Chrysanthemum L., gerberas Gerbera G. As a result, the algorithm for performing tests related to study of new insectoacaricides on flower cultures in greenhouses is developed. Methodology instructions that we offer for assessment of abundance of major pests for flower cultures of protected ground and determination of biological effectiveness of new insectoacaricides are intended for ensuring the uniform methodological approach to performance of registration tests of modern means to fight against these pests and opportunity for analysis of tests in various agroclimatic areas and obtaining a reasonable general conclusion and findings related to pesticides taking into account international requirements. Актуальность. Анализ современного ассортимента пестицидов, применяемых в цветочных оранжереях, показал существенный недостаток количества разрешённых препаратов. Методики для регистрационных испытаний инсектицидов для защиты цветочных культур в защищенном грунте сегодня отсутствуют. Целью наших исследований была разработка методических подходов к оценке численности основных вредителей цветочных культур защищённого грунта и определению биологической эффективности новых инсектоакарицидов.Материал и методика. К вредителям цветочных культур, наиболее часто встречающимся в защищённом грунте, можно отнести следующих фитофагов – тли: персиковая – Myzus persicae Sulz., бахчевая – Aphis gossypii Glov., обыкновенная картофельная – Aulacorthum solani Kalt., большая картофельная – Macrosiphum euphorbiae Thom., зеленая розанная – Macrosiphum rosae Linn.; белокрылки: тепличная белокрылка – Trialeurodes vaporariorum Wstw., табачная белокрылка – Bemisia tabaci Genn.; трипсы: табачный – Thrips tabaci Lind., розанный – Th. fuscipennis Hal., западный цветочный – Frankliniella occidentalis Perg., разноядный – F. intonsa Tryb., оранжерейный – Heliothrips haemorrhoidalis Bouche; клещи: обыкновенный паутинный – Tetranychus urticae Koch.; красный тепличный – T. cinnabarinus Boisd. Исследования по оценке численности основных вредителей цветочных культур и подбору методов определения биологической эффективности инсектоакарицидов проводили в цветочных оранжереях Ленинградской области на культурах: чайно-гибридная роза Rosa L., хризантема Chrysanthemum L., гербера Gerbera G. В результате разработан алгоритм проведения опытов по изучению новых инсектоакарицидов на цветочных культурах в теплицах.Результаты. Методические указания, предложенные нами для оценки численности основных вредителей цветочных культур защищённого грунта и определения биологической эффективности новых инсектоакарицидов, предназначены для обеспечения единого методического подхода в проведении регистрационных испытаний современных средств борьбы с этими вредителями, возможности анализа и сравнения результатов опытов в разных агроклиматических точках и получения обоснованного общего заключения и выводов по препарату с учетом международных требований.

Nuclear Reaction Rates and Primordial 6^6Li

We examine the possibility that Big Bang Nucleosynthesis (BBN) may produce non-trivial amounts of $^6$Li. If a primordial component of this isotope could be observed, it would provide a new fundamental test of Big-Bang cosmology, as well as new constraints on the baryon density of the universe. At present, however, theoretical predictions of the primordial $^6$Li abundance are extremely uncertain due to difficulties in both theoretical estimates and experimental determinations of the deuterium-plus-alpha radiative capture reaction cross-section. We also argue that present observational capabilities do not yet allow the detection of primeval $^6$Li in very metal-poor stars of the galactic halo. However, if the critical cross section is towards the upper end of its plausible range, then improvements in $^6$Li detection capabilities may allow the establishment of $^6$Li as another product of BBN. It is also noted that a primordial $^6$Li detection could help resolve current concerns about the extragalactic D/H determination.Comment: 10 pages, REVTeX, 5 PostScript figures with psfig. Submitted to Physical Review

Сравнительная характеристика пневмоний, вызванных Mycoplasma pneumoniae, у детей

The urgency of the problem of community-acquired pneumonia in children is due to the high incidence rate. In the etiological structure of bacterial pneumonia, Streptococcus pneumoniae and Mycoplasma pneumonia (Mp) prevail.Purpose: to identify clinical, laboratory and instrumental features of mycoplasmal pneumonia in children.Materials and methods. A retrospective,  single-center cohort study  of  266  case  histories  of  children  aged  4 months to 17 years who were in Children’s City Clinical Hospital No. 9 in 2019 with a referral diagnosis of pneumonia was carried out. To verify the diagnosis of pneumonia, the method of chest X-ray was used, for the etiological diagnosis, the method of PCR swabs from the nasopharynx, ELISA for the detection of antibodies of the IgM and IgG classes was used. Results. The diagnosis  of  pneumonia was confirmed in 190 children. The diagnosis of pneumonia caused by M. pneumoniae (MpP) was established in 76 (40%) children, they made up the 1st group. The remaining 114 (60%) children with community-acquired pneumonia of another etiology (CAP) made up the 2nd group – comparisons. The diagnosis of MpP was confirmed in 46 (60.5%) children by the detection of IgM, in 12 (15.8%) by the detection of Mp genetic material, and in  18  (23.7%) by positive both IgM and PCR. The median age of children in the group with MpP was 9.6 years, in the comparison group – 4 years (p<0.01). Significantly more often MpP occurs in children aged 11–17 years (p < 0.01), and CAP – up to 7 years (p < 0.01). With MpP, catarrhal phenomena in the form of hyperemia of the oropharynx, nasal congestion, and unproductive cough are observed less frequently than with CAP. With MpP, rales in the lungs are heard more often than with CAP, they are significantly more often wet (p<0.01). Respiratory failure and dyspnea are less common in MpP than in CAP. Bilateral lesions and lesions of the upper lobe of the lungs are more often detected in MpP, and in CAP – right-sided lesions. In the general blood test, leukocytosis, incl. above 15  thousand/µl,  as well as leukopenia below 4 thousand/µl were significantly more frequent in the group of patients with CAP (p<0.01). Conclusion. No clear clinical and laboratory criteria for mycoplasmal etiology of pneumonia have been obtained, which dictates the need for laboratory confirmation for the choice of therapy tactics.Актуальность проблемы внебольничных пневмоний у детей обусловлена высоким  уровнем  заболеваемости. В этиологической структуре бактериальных пневмоний превалируют Streptococcus pneumoniae и Mycoplasma pneumoniae.Цель: выявление клинико-лабораторных и инструментальных особенностей микоплазменной пневмонии у детей.Материалы и методы: проведено ретроспективное, одноцентровое когортное исследование 266 историй болезни детей в возрасте от 4 месяцев до 17 лет, находившихся в Детской городской клинической больнице № 9 в 2019 г. с направительным диагнозом «Пневмония». Для верификации диагноза пневмонии использовали рентгенографию грудной клетки, для этиологического диагноза – ПЦР мазков из носоглотки, ИФА для обнаружения антител класса IgM и IgG.Результаты: диагноз «Пневмония» был подтвержден у 190 детей. Микоплазменная пневмония (MpП) была установлена у 76 (40%) детей, они составили 1-ю группу (у 46 (60,5%) детей обнаружены IgM, у 12 (15,8%) – положительная ПЦР, а у 18 (23,7%) – положительные и IgM, и ПЦР). Остальные 114 (60%) детей с внебольничной пневмонией другой этиологии (ВП) составили 2-ю группу – сравнения. Медиана возраста детей в группе с МрП составила 9,6 лет, в группе сравнения – 4 года (р<0,01). Достоверно чаще MpП встречается у детей в возрасте 11–17 лет (р < 0,01), а ВП – до 7 лет (р < 0,01). При MpП катаральные явления в виде гиперемии ротоглотки, заложенности носа, малопродуктивного кашля наблюдаются реже, чем при ВП. При MpП чаще выслушиваются хрипы в легких, чем при ВП, достоверно чаще они влажные (р<0,01). При MpП дыхательная недостаточность и одышка наблюдаются реже, чем при ВП. Поражение верхней доли легких чаще выявляется при MpП, а при ВП – правостороннее поражение. В общем анализе крови лейкоцитоз, в том числе выше 15 тыс./мкл, а также лейкопения ниже 4 тыс./мкл были достоверно чаще в группе больных с ВП (р<0,01).Заключение: не получено четких клинико-лабораторных критериев пневмонии микоплазменной этиологии, что диктует необходимость лабораторного подтверждения этиологии пневмонии для выбора тактики терапии

Matter in Strong Magnetic Fields

The properties of matter are significantly modified by strong magnetic fields, $B>>2.35\times 10^9$ Gauss ($1 G =10^{-4} Tesla$), as are typically found on the surfaces of neutron stars. In such strong magnetic fields, the Coulomb force on an electron acts as a small perturbation compared to the magnetic force. The strong field condition can also be mimicked in laboratory semiconductors. Because of the strong magnetic confinement of electrons perpendicular to the field, atoms attain a much greater binding energy compared to the zero-field case, and various other bound states become possible, including molecular chains and three-dimensional condensed matter. This article reviews the electronic structure of atoms, molecules and bulk matter, as well as the thermodynamic properties of dense plasma, in strong magnetic fields, $10^9G << B < 10^{16}G$. The focus is on the basic physical pictures and approximate scaling relations, although various theoretical approaches and numerical results are also discussed. For the neutron star surface composed of light elements such as hydrogen or helium, the outermost layer constitutes a nondegenerate, partially ionized Coulomb plasma if $B<<10^{14}G$, and may be in the form of a condensed liquid if the magnetic field is stronger (and temperature $<10^6$ K). For the iron surface, the outermost layer of the neutron star can be in a gaseous or a condensed phase depending on the cohesive property of the iron condensate.Comment: 45 pages with 9 figures. Many small additions/changes. Accepted for publication in Rev. Mod. Phy

Comparative constructions of similarity in Northern Samoyedic languages

The purpose of this paper is to analyze the suffixes which are used in Northern Samoyedic languages to build comparative constructions of equality. Depending on the language, the suffixes may perform three functions: word-building, form-building, and inflectional. When they mark the noun, they serve as simulative suffixes and are employed to build object comparison. In the inflectional function, these suffixes mark the verb and are a means of constructing situational comparison. In this case, they signal the formation of a special mood termed the Approximative. This paper provides a detailed description of the Approximative from paradigmatic and syntagmatic perspectives