170 research outputs found
The labidostommatid palpus: a morphological enigma (Acariformes: Prostigmata)
International audienceHypotheses are reviewed concerning which segments of the primitively five-segmented palpus are coalesced to form the simple, linear, four-segmented form characteristic of labidostommatid mites. Among alternatives, those of either a femurogenu or a tibiotarsus are not based on convincing evidence. Instead, based on ontogeny of the peculiar palpal structure and chaetome of labidostommatids, a case is made that the proximal segment, which bears a single, ventral, postlarval seta, is a basifemur, with the trochanter autapomorphically either coalesced with it or subsumed into the base. Consequently, the second segment is a telofemur, articulating with the third article, which is an unusual, coalescent genuotibia. The phylogenetic significance of various interpretations of segmental coalescence are considered. Ontogenetic studies of palpal musculature and gene expression are needed to provide more substantive evidence
Models of Dissertation Defense: From Post-Reform University to Soviet Era (Case of Saint Petersburg University)
This study explores the issue of obtaining academic degrees in prerevolutionary Russia, a process that was an integral part of scientific initiation, allowing individuals to enter the ranks of the country’s intellectual elite. The aim of this paper is to determine the interplay between socio-political, corporate, and scientific elements in shaping the discourse of academic disputation. The analysis presented herein draws upon data primarily concerning Saint Petersburg University, which was a leading center for Russian scholarly activity. Specifically, this research utilizes unpublished materials from the minutes of the University Council meetings, journals of public assemblies of various faculties, and archives managed by the Saint Petersburg educational district, containing information on planned disputes. The authors conclude that there were eight formal obstacles a candidate had to overcome in the pursuit of a degree. The key hurdle was access to the public defense, which was a closed affair, being an internal corporate matter that excluded not only the degree candidate but also external authorities and society at large. The public defense of a thesis served more as a socially significant rite of corporate initiation, demonstrating the public importance of the corporation
Neutron-H potentials and the H-properties
The continuum resonance spectrum of H (H++) is investigated by
use of the complex scaled hyperspherical adiabatic expansion method. The
crucial H-neutron potential is obtained by switching off the Coulomb part
from successful fits to He-proton experimental data. These two-body
potentials must be expressed exclusively by operators conserving the
nucleon-core mean field angular momentum quantum numbers. The energies
and widths of the ground-state resonance and the lowest two
excited and -resonances are found to be MeV,
MeV and MeV, respectively. These results agree with
most of the experimental data. The energy distributions of the fragments after
decay of the resonances are predicted.Comment: 26 pages, 8 tables, 7 figures. Accepted for publication in Nucl.
Phys.
Development of the digital chart in Belarus: results and situations in international ratings
В Республике Беларусь процессы цифровизации динамично развиваются. Положительную динамику им придают системные меры государственного регулирования как на уровне главы государства, так и отдельных органов государственного управления. Закономерным итогом совместной работы является стабильно высокие позиции Беларуси в мировых рейтингах. В настоящей статье рассматривается современное состояние и подходы к развитию цифровизации в Беларуси. Анализируются ключевые нормативные правовые акты в этой сфере, а также место Республики Беларусь в основных мировых рейтингах.This article examines the current state and approaches to the development of digitalization in Belarus. The key regulatory legal acts in this area are analyzed, as well as the place of the Republic of Belarus in the main world rankings. In the Republic of Belarus digitalization processes are developing dynamically. Systemic measures of state regulation both at the level of the Head of State and individual government bodies give them a positive dynamic. The natural result of the joint work is the consistently high position of Belarus in the world rankings
Structure of unbound neutron-rich He studied using single-neutron transfer
The 8He(d,p) reaction was studied in inverse kinematics at 15.4A MeV using
the MUST2 Si-CsI array in order to shed light on the level structure of 9He.
The well known 16O(d,p)17O reaction, performed here in reverse kinematics, was
used as a test to validate the experimental methods. The 9He missing mass
spectrum was deduced from the kinetic energies and emission angles of the
recoiling protons. Several structures were observed above the neutron-emission
threshold and the angular distributions were used to deduce the multipolarity
of the transitions. This work confirms that the ground state of 9He is located
very close to the neutron threshold of 8He and supports the occurrence of
parity inversion in 9He.Comment: Exp\'erience GANIL/SPIRAL1/MUST
New insight into the low-energy He spectrum
The spectrum of He was studied by means of the He(,)He
reaction at a lab energy of 25 MeV/n and small center of mass (c.m.) angles.
Energy and angular correlations were obtained for the He decay products by
complete kinematical reconstruction. The data do not show narrow states at
1.3 and 2.4 MeV reported before for He. The lowest resonant
state of He is found at about 2 MeV with a width of 2 MeV and is
identified as . The observed angular correlation pattern is uniquely
explained by the interference of the resonance with a virtual state
(limit on the scattering length is obtained as fm), and with
the resonance at energy MeV.Comment: 5 pages, 4 figures, 2 table
Three-body correlations in direct reactions: Example of Be populated in reaction
The Be continuum states were populated in the charge-exchange reaction
H(Li,Be) collecting very high statistics data ( events) on the three-body ++ correlations. The
Be excitation energy region below MeV is considered, where the
data are dominated by contributions from the and states. It is
demonstrated how the high-statistics few-body correlation data can be used to
extract detailed information on the reaction mechanism. Such a derivation is
based on the fact that highly spin-aligned states are typically populated in
the direct reactions.Comment: submitted to Physical Review
10He low-lying states structure uncovered by correlations
The 0+ ground state of the 10He nucleus produced in the 3H(8He,p)10He
reaction was found at about MeV (\Gamma ~ 2 MeV) above the
three-body 8He+n+n breakup threshold. Angular correlations observed for 10He
decay products show prominent interference patterns allowing to draw
conclusions about the structure of low-energy excited states. We interpret the
observed correlations as a coherent superposition of the broad 1- state having
a maximum at energy 4-6 MeV and the 2+ state above 6 MeV, setting both on top
of the 0+ state "tail". This anomalous level ordering indicates that the
breakdown of the N=8 shell known in 12Be thus extends also to the 10He system.Comment: 5 pages, 5 figure
Digital receivers for low-frequency radio telescopes UTR-2, URAN, GURT
This paper describes digital radio astronomical receivers used for decameter
and meter wavelength observations. This paper describes digital radio
astronomical receivers used for decameter and meter wavelength observations.
Since 1998, digital receivers performing on-the-fly dynamic spectrum
calculations or waveform data recording without data loss have been used at the
UTR-2 radio telescope, the URAN VLBI system, and the GURT new generation radio
telescope. Here we detail these receivers developed for operation in the strong
interference environment that prevails in the decameter wavelength range. Data
collected with these receivers allowed us to discover numerous radio
astronomical objects and phenomena at low frequencies, a summary of which is
also presented.Comment: 24 pages, 15 figure
6He + 9Be reactions at 16.8 MeV
6 pags.; 6 figs.Reactions of a 16.8 MeV 6He beam with a 9Be target have been investigated using highly segmented detector setup covering a large solid angle. Data on elastic and quasi-free scattering, as well as two-neutron transfer, are reported. The results for elastic scattering are fairly well reproduced by a CDCC calculation, in agreement with the interpretation of a breakup effect already observed for the scattering of 6He on other light targets. Exotic quasi-free scattering of 6He on α-cluster in 9Be is clearly observed. Inclusive and coincident events were used to extract information on the two-neutron transfer reaction 9Be(6He, α)11Be. Sequential decay of the 11Be state at the excitation energy Ex = 10.6 MeV through different channels is discussed. © 2010 SIF, Springer-Verlag Berlin Heidelberg.We would like to thank the technical staff at the RNB facility
at the CRC-Louvain-la-Neuve for their valuable contributions
to this work.Peer Reviewe
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