33 research outputs found
Magnetized Iron Atmospheres for Neutron Stars
Using a Hartree-Fock formalism, we estimate energy levels and photon cross
sections for atomic iron in magnetic fields B ~ 10^13 G. Computing ionization
equilibrium and normal mode opacities with these data, we construct LTE neutron
star model atmospheres at 5.5 < Log(T_eff) < 6.5 and compute emergent spectra.
We examine the dependence of the emergent spectra on T_eff and B. We also show
the spectral variation with the angle between the magnetic field and the
atmosphere normal and describe the significant limb darkening in the X-ray
band. These results are compared with recent detailed computations of neutron
star H model atmospheres in high fields and with low field Fe and H model
atmospheres constructed from detailed opacities. The large spectral differences
for different surface compositions may be discernible with present X-ray data;
we also note improvements needed to allow comparison of Fe models with high
quality spectra.Comment: 18 pages with 5 eps figures, accepted for publication in ApJ Replaced
due to clerical error only: one more author, no new conten
Equation of state of a strongly magnetized hydrogen plasma
The influence of a constant uniform magnetic field on the thermodynamic
properties of a partially ionized hydrogen plasma is studied. Using the method
of Green' s function various interaction contributions to the thermodynamic
functions are calculated. The equation of state of a quantum magnetized plasma
is presented within the framework of a low density expansion up to the order
e^4 n^2 and, additionally, including ladder type contributions via the bound
states in the case of strong magnetic fields (2.35*10^{5} T << B << 2.35*10^{9}
T). We show that for high densities (n=10^{27-30} m^{-3}) and temperatures
T=10^5 - 10^6 K typical for the surface of neutron stars nonideality effects
as, e.g., Debye screening must be taken into account.Comment: 12 pages, 2 Postscript figures. uses revtex, to appear in Phys. Rev.
Ionization and dissociation equilibrium in strongly-magnetized helium atmosphere
Recent observations and theoretical investigations of neutron stars indicate
that their atmospheres consist not of hydrogen or iron but possibly other
elements such as helium. We calculate the ionization and dissociation
equilibrium of helium in the conditions found in the atmospheres of magnetized
neutron stars. For the first time this investigation includes the internal
degrees of freedom of the helium molecule. We found that at the temperatures
and densities of neutron star atmospheres the rotovibrational excitations of
helium molecules are populated. Including these excitations increases the
expected abundance of molecules by up to two orders of magnitude relative to
calculations that ignore the internal states of the molecule; therefore, if the
atmospheres of neutron stars indeed consist of helium, helium molecules and
possibly polymers will make the bulk of the atmosphere and leave signatures on
the observed spectra from neutron stars. We applied our calculation to nearby
radio-quiet neutron stars with B_{dipole}~10^{13}-10^{14} G. If helium
comprises their atmospheres, our study indicates that isolated neutron stars
with T_{BB}~10^6 K such as RXJ0720.4-3125 and RXJ1605.3+3249 will have He^+
ions predominantly, while isolated neutron stars with lower temperature
(T_{BB}~5x10^5 K) such as RXJ1856.5-3754 and RXJ0420.0-5022 will have some
fraction of helium molecules. If helium molecules are abundant, their
spectroscopic signatures may be detected in the optical, UV and X-ray band.
(Abridged)Comment: 12 pages, 12 figures, accepted for publication in MNRA
Deuterium chemistry in the primordial gas
We review and update some aspects of deuterium chemistry in the
post-recombination Universe with particular emphasis on the formation and
destruction of HD. We examine in detail the available theoretical and
experimental data for the leading reactions of deuterium chemistry and we
highlight the areas where improvements in the determination of rate
coefficients are necessary to reduce the remaining uncertainties. We discuss
the cooling properties of HD and the modifications to the standard cooling
function introduced by the presence of the cosmological radiation field.
Finally, we consider the effects of deuterium chemistry on the dynamical
collapse of primordial clouds in a simple ``top-hat'' scenario, and we
speculate on the minimum mass a cloud must have in order to be able to cool in
a Hubble time.Comment: 22 pages, 10 figures, LaTeX. Earth and Planetary Sciences, in pres
ЭМОЦИОНАЛЬНЫЙ ИНТЕЛЛЕКТ И УРОВЕНЬ ПРОФЕССИОНАЛЬНОЙ ПОДГОТОВКИ ОБУЧАЮЩИХСЯ, ОРИЕНТИРОВАННЫХ НА ПОДГОТОВКУ ПО ПРОФИЛЮ «ОБЩЕСТВЕННОЕ ЗДОРОВЬЕ И ЗДРАВООХРАНЕНИЕ»
Background. To Investigate features of emotional intelligence of students oriented to become health care managers.Materials and methods. The study was conducted at the Department of Public Health and Health Care Service named after N.A. Semashko, the Center for Master’s Programs and the Graduate School of Health Care of I.M. Sechenov First Moscow State Medical University. The study involved 242 students of Sechenov University who were trained in the field of medical and preventive care, as well as master students and residents who were trained to become health care managers. The study included 80 men (33.1%) and 162 women (66.9%). The groups did not differ by sex and age.The subjects were included in 3 groups:– group 1 (comparison group 1) – 66 people who underwent postgraduate training (interns, residents, masters);– group 2 (comparison group 2) – 104 students of the medical and preventive faculty of Sechenov University,– group 3 (core) – 72 students who completed the course “Factory of Health Leaders”.During the study, indicators of emotional intelligence (emotional awareness, managing one’s emotions, empathy, self-motivation, recognition of other people’s emotions) were evaluated. Evaluation using scoring system was also based on personality self-actualization (the desire for self-actualization, time orientation, values, a look at the nature of a person, the need for knowledge, creativity, autonomy, spontaneity, self-understanding, autosympathy, contact, flexibility in communication).Results. The result of the study is an assessment of characteristics of the students’ emotional intelligence, who are training in the “Public Health and Health Care” program, which are valuable for identification of the abilities of understanding personality relationships that are represented in emotions and in management of the emotional sphere based on decision-making.Conclusion. The results of the study indicate that the parameters included in the discriminant models of multiple logistic regression analysis can be used as possible predictors for evaluating the parameters of emotional intelligence and the test of personality self-actualization, which, in turn, with a high degree of sensitivity and specificity determine students’ membership in the selected group and students of the Health Leaders Factory program. Based on these models, it can be assumed that among students the parameters of emotional intelligence are closely associated with leadership qualities. These models can be used during testing of students for identification of students with leadership qualities in the early stages of training in order to fully reveal their potential when studying in training programs for health leaders.Цель. Изучение особенностей эмоционального интеллекта студентов, характерных для обучающихся ориентированных на подготовку по профилю «Общественное здоровье и здравоохранение».Материалы и методы. Исследование проведено на базе кафедры общественного здоровья и здравоохранения им. Н.А. Семашко, Центра Магистерских программ и Высшей школы управления здравоохранением МГМУ им. И.М. Сеченова. Участниками исследования (242 человека) представлены студентами Сеченовского Университета, проходившими подготовку по направлению медико-профилактическое дело, а также магистрантами и ординаторами, проходившими обучение по профилю «Общественное здоровье и здравоохранение».В исследование было включено 80 мужчин (33,1%) и 162 женщины (66,9%). Группы не различались по половозрастному признаку.Испытуемые были включены в 3 группы:– группа 1 (группа сравнения 1) – 66 человек, проходившиих постдипломное обучение (интерны, ординаторы, магистры);– группа 2 (группа сравнения 2) – 104 студента медико-профилактического факультета Сеченовского Университета,– группа 3 (основная) – 72 студента, которые прошли курс «Фабрики лидеров здравоохранения».В ходе исследования оценивали показатели эмоционального интеллекта (эмоциональная осведомленность, управление своими эмоциями, эмпатия, самомотивация, распознавание эмоций других людей). Также была выполнена балльная оценка самоактуализации личности (стремление к самоактуализации, ориентация во времени, ценности, взгляд на природу человека, потребность в познании, креативность, автономность, спонтанность, самопонимание, аутосимпатия, контактность, гибкость в общении).Результаты. Результатом проведенного исследования является оценка характеристик эмоционального интеллекта обучающихся, ориентированных на подготовку по профилю «Общественное здоровье и здравоохранение», для выявления способностей понимания отношений личности, репрезентируемых в эмоциях и управления эмоциональной сферой на основе принятия решений.Заключение. Результаты исследования свидетельствовуют, что параметры, включенные в дискриминантные модели множественного логистического регрессионного анализа могут быть использованы в качестве возможных предикторов оценки параметров эмоционального интеллекта и теста самоактуализации личности, что в свою очередь, с высокой долей чувствительности и специфичности моделируют принадлежность студентов к группе прошедших отбор и обучавшихся по программе Фабрика Лидеров Здравоохранениря. На основании данных моделей можно предположить, что среди студентов параметры эмоционального интеллекта тесным образом ассоциированы с лидерскими качествами. Данные модели могут быть использованы при проведении тестирования обучающихся для выявления на ранних этапах обучения студентов, обладающих лидерскими качествами, с целью наиболее полного раскрытия их потенциала при обучении по программам подготовки лидеров здравоохранения
Quantum computation with trapped polar molecules
We propose a novel physical realization of a quantum computer. The qubits are
electric dipole moments of ultracold diatomic molecules, oriented along or
against an external electric field. Individual molecules are held in a 1-D trap
array, with an electric field gradient allowing spectroscopic addressing of
each site. Bits are coupled via the electric dipole-dipole interaction. Using
technologies similar to those already demonstrated, this design can plausibly
lead to a quantum computer with qubits, which can perform CNOT gates in the anticipated decoherence time of s.Comment: 4 pages, RevTeX 4, 2 figures. Edited for length and converted to
RevTeX, but no substantial changes from earlier pdf versio
Hydrogen Molecules In Superstrong Magnetic Field: II. Excitation Levels
We study the energy levels of H molecules in a superstrong magnetic field
(B\go 10^{12} G), typically found on the surfaces of neutron stars. The
interatomic interaction potentials are calculated by a Hartree-Fock method with
multi-configurations assuming electrons are in the ground Landau state. Both
the aligned configurations and arbitrary orientations of the molecular axis
with respect to the magnetic field axis are considered. Different types of
molecular excitations are then studied: electronic excitations, aligned (along
the magnetic axis) vibrational excitations, transverse vibrational excitations
(a constrained rotation of the molecular axis around the magnetic field line).
Similar results for the molecular ion H are also obtained and compared
with previous variational calculations. Both numerical results and analytical
fitting formulae are given for a wide range of field strengths. In contrast to
the zero-field case, it is found that the transverse vibrational excitation
energies can be larger than the aligned vibration excitation, and they both can
be comparable or larger than the electronic excitations. For B\go
B_{crit}=4.23\times 10^{13} G, the Landau energy of proton is appreciable and
there is some controversy regarding the dissociation energy of H. We show
that H is bound even for and that neither proton has a Landau
excitation in the ground molecular state.Comment: Revtex (45 pages), 3 postscript figures; Phys. Rev. A in pres
Modelling mid-Z element atmospheres for strongly-magnetized neutron stars
We construct models for strongly-magnetized neutron star atmospheres composed
of mid-Z elements (carbon, oxygen and neon) with magnetic fields
B=10^{12}-10^{13} G and effective temperatures Teff=(1-5)*10^6 K; this is done
by first addressing the physics relevant to strongly-magnetized plasmas and
calculating the equation of state and polarization-dependent opacities. We then
obtain the atmosphere structure and spectrum by solving the radiative transfer
equations in hydrostatic and radiative equilibrium. In contrast to hydrogen
opacities at the relevant temperatures, mid-Z element opacities are dominated
by numerous bound-bound and bound-free transitions. Consequently, temperature
profiles are closer to grey profiles, and photosphere densities are lower than
in the hydrogen case. Mid-Z element atmosphere spectra are significantly softer
than hydrogen atmosphere spectra and show numerous absorption lines and edges.
The atmosphere spectra depend strongly on surface composition and magnetic
field but weakly on surface gravity. Absorption lines are primarily broadened
by motional Stark effects and the (unknown) surface magnetic field
distribution. Given the multiple absorption features observed from several
isolated neutron stars, it is possible to determine, with existing X-ray data,
the surface composition, magnetic field, temperature, and gravitational
redshift; we present qualitative comparisons between our model spectra and the
neutron stars 1E1207.4-5209 and RX J1605.3+3249. Future high-resolution X-ray
missions such as Constellation-X will measure the gravitational redshift with
high accuracy by resolving narrow absorption features, and when combined with
radius measurements, it will be possible to uniquely determine the mass and
radius of isolated neutron stars. (Abridged)Comment: 16 pages, 22 figures, accepted for publication in MNRA
Matter in Strong Magnetic Fields
The properties of matter are significantly modified by strong magnetic
fields, Gauss (), 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,
. 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 , and may be in
the form of a condensed liquid if the magnetic field is stronger (and
temperature 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