Pauli equation and the method of supersymmetric factorization

We consider different variants of factorization of a 2x2 matrix Schroedinger/Pauli operator in two spatial dimensions. They allow to relate its spectrum to the sum of spectra of two scalar Schroedinger operators, in a manner similar to one-dimensional Darboux transformations. We consider both the case when such factorization is reduced to the ordinary 2-dimensional SUSY QM quasifactorization and a more general case which involves covariant derivatives. The admissible classes of electromagnetic fields are described and some illustrative examples are given.Comment: 18 pages, Late

Low-energy Antiproton Interaction with Helium

An ab initio potential for the interaction of the neutral helium atom with antiprotons and protons is calculated using the Born-Oppenheimer approximation. Using this potential, the annihilation cross section for antiprotons in the energy range 0.01 microvolt to 1 eV is calculated.Comment: 13 pages, 7 figures, LaTe

Access to Scientific Publications: The Scientist's Perspective

BACKGROUND: Scientific publishing is undergoing significant changes due to the growth of online publications, increases in the number of open access journals, and policies of funders and universities requiring authors to ensure that their publications become publicly accessible. Most studies of the impact of these changes have focused on the growth of articles available through open access or the number of open-access journals. Here, we investigated access to publications at a number of institutes and universities around the world, focusing on publications in HIV vaccine research--an area of biomedical research with special importance to the developing world. METHODS AND FINDINGS: We selected research papers in HIV vaccine research field, creating: 1) a first set of 50 most recently published papers with keywords "HIV vaccine" and 2) a second set of 200 articles randomly selected from those cited in the first set. Access to the majority (80%) of the recently published articles required subscription, while cited literature was much more accessible (67% freely available online). Subscriptions at a number of institutions around the world were assessed for providing access to subscription-only articles from the two sets. The access levels varied widely, ranging among institutions from 20% to 90%. Through the WHO-supported HINARI program, institutes in low-income countries had access comparable to that of institutes in the North. Finally, we examined the response rates for reprint requests sent to corresponding authors, a method commonly used before internet access became widespread. Contacting corresponding authors with requests for electronic copies of articles by email resulted in a 55-60% success rate, although in some cases it took up to 1.5 months to get a response. CONCLUSIONS: While research articles are increasingly available on the internet in open access format, institutional subscriptions continue to play an important role. However, subscriptions do not provide access to the full range of HIV vaccine research literature. Access to papers through subscriptions is complemented by a variety of other means, including emailing corresponding authors, joint affiliations, use of someone else's login information and posting requests on message boards. This complex picture makes it difficult to assess the real ability of scientists to access literature, but the observed differences in access levels between institutions suggest an unlevel playing field, in which some researchers have to spend more efforts than others to obtain the same information

CONSTRUCTION OF FIVE-MEMBERED HETEROCYCLES USING CALCIUM CARBIDE

This work was supported by the Grant Council of the President of the Russian Federation (МК-2615.2021.1.3)

Unusual weak increase of Curie temperature and lattice parameters in Pr2Fe16.5Zr0.5

Crystal structure and magnetic and thermomagnetic properties of the Pr2Fe17-xMx compounds with M = Ti, V, Cr, Zr, Nb have been studied. The change of interatomic distances is not enough to explain the growth of the Curie point and it is necessary to assume the distribution of M = Ti, V, Cr, Nb atoms over the lattice positions, similar to that previously published for the Nd2Fe17-xMx compounds. It was established by neutron diffraction that Zr atoms substitute for Pr atoms in the 6c site and do not substitute for Fe atoms as might be expected from the original formula Pr2Fe16.5Zr0.5. So, the real composition of the substituted compound studied is Pr14.8(8)Zr0.52(8)Fe17. The magnetic moment of Fe atom and the magnetocaloric effect in the Pr2Fe17-xMx compounds decrease with decreasing Fe content. © Published under licence by IOP Publishing Ltd.Russian Foundation for Basic Research, RFBR: 18-02-00294The research was carried out within the state assignment of Minobrnauki of Russia (themes “Magnet” No. АААА-А18-118020290129-5, “Alloys” and “Flux” No. АААА-А18-118020190112-8) and supported in part by RFBR (project No. 18-02-00294)

The etiology of individual differences in maths beyond IQ: insights from 12 year-old twins.

This study investigated the etiology of individual differences in mathematics and the nature of the relationship of mathematics with reading and g. A sample of 13,262 12-year-old twins from the Twins Early Development Study (TEDS) was assessed on 11 measures of mathematics, reading, and general cognitive abilities (g). A variable of ‘Pure Mathematics’ was obtained by removing the common variance with reading and g from mathematical scores. Controlling for reading and g did not reduce variability in mathematics but eliminated the influences of shared environment in the etiology of individual differences. Pure Mathematics remained moderately heritable (.44)

ФАУНА ЛЕГОЧНЫХ ГЕЛЬМИНТОВ В ОРГАНИЗМЕ ХОЗЯИНА, ЕЕ БИОЛОГИЧЕСКАЯ И ТАКСОНОМИЧЕСКАЯ КЛАССИФИКАЦИЯ

Object of study: Studies of lung helminths from various groups were performed. Elaboration of biological and taxonomic classification of these species has been proposed.Materials and methods: 16 species from families Cervidae, Bovidae, Leporidae and humans were studied for lung helminths inRussia (South and central),Armenia,Bulgaria,Poland. The helminths found were studied using a scope of traditional and elaborated helminthological methods.Results and discussion: In lungs of mammals studied 23 helminth species have been found including 1 of Taeniidae (Echinococcus granulosus), 4 of Dictyocaulidae and 18 of Protostrongylidae. We have divided species composition of these lung helminths into three biological groups. The first biological group included nematodes from Dictyocaulidae family. Life cycles of those helminths are monoxenous (they are geohelminths). The second group includes helminths from family Protostrongylidae. Their life cycles include intermediate hosts – land snails and so they are dixenous (biohelminths). The third group includes an agent of a quite dangerous zoonosis – Echinococcus granulosis larvae. These cestodes also develop per dixenous type, but their intermediate hosts are vertebrates with definitive hosts also vertebrate, mostly carnivores. Taxonomic classification for family Protostrongylidae haelminths is also proposed.Цель исследования: Провести изучение различных групп легочных гельминтов; разработать биологическую и таксономическую классификацию данного вида гельминтов.Материалы и методы: Проведены исследования 16 видов гельминтов семейств Cervidae, Bovidae, Leporidae, а также легочных гельминтов человека на территории России (Юг и центральные районы), Армении, Болгарии, Польши. Обнаруженные гельминты были изучены с использованием традиционных и новых методов гельминтологического исследования.Результаты и обсуждение: В легких у исследованных млекопитающих, найдено 23 вида гельминтов, включая 1 Taeniidae (Echinococcus granulosus), 4 Dictyocaulidae и 18 Protostrongylidae. Мы разделили все эти легочные гельминты на три биологические группы. В первую группу (геогельминты) вошли нематоды семейства Dictyocaulidae. Жизненный цикл данного вида гельминтов моноксенический, осуществляется прямым путём, без промежуточных хозяев. Вторая группа (биогельминты) включала в себя гельминты семейства Protostrongylidae. Характерным признаком является участие в их биологическом цикле промежуточных хозяев — наземных моллюсков. К третьей группе были отнесены возбудители довольно опасного зооноза – Echinococcus granulosis larvae. Эти цестоды развиваются со сменой хозяев, но их промежуточными хозяевами являются позвоночные млекопитающие, имеющие окончательных хозяев – также позвоночных, в основном, плотоядных животных. Нами также предложена таксономическая классификация семейства Protostrongylidae haelminths

Antiproton-deuteron annihilation at low energies

Recent experimental studies of the antiproton-deuteron system at low energies have shown that the imaginary part of the antiproton-deuteron scattering length is smaller than the antiproton-proton one. Two- and three-body systems with strong annihilation are investigated and a mechanism explaining this unexpected relation between the imaginary parts of the scattering lengths is proposed.Comment: 6 pages, 3 figures, to be published in The European Physical Journal