836 research outputs found
Molecular line opacity of LiCl in the mid-infrared spectra of brown dwarfs
We present a complete line list for the X 1Sigma+ electronic ground state of
LiCl computed using fully quantum-mechanical techniques. This list includes
transition energies and oscillator strengths in the spectral region
0.3-39,640.7 cm-1 for all allowed rovibrational transitions in absorption
within the electronic ground state. The calculations were performed using an
accurate hybrid potential constructed from a spectral inversion fit of
experimental data and from recent multi-reference single- and double-excitation
configuration interaction calculations. The line list was incorporated into the
stellar atmosphere code PHOENIX to compute spectra for a range of young to old
T dwarf models. The possibility of observing a signature of LiCl in absorption
near 15.8 microns is addressed and the proposal to use this feature to estimate
the total lithium elemental abundance for these cool objects is discussed.Comment: 8 pages, 2 figures, 1 table. Accepted for publication in ApJ 613,
Sept. 20 200
Electric-field noise from carbon-adatom diffusion on a Au(110) surface: first-principles calculations and experiments
The decoherence of trapped-ion quantum gates due to heating of their motional
modes is a fundamental science and engineering problem. This heating is
attributed to electric-field noise arising from the trap-electrode surfaces. In
this work, we investigate the source of this noise by focusing on the diffusion
of carbon-containing adsorbates on the surface of Au(110). We show by density
functional theory, based on detailed scanning probe microscopy, how the carbon
adatom diffusion on the gold surface changes the energy landscape, and how the
adatom dipole moment varies with the diffusive motion. A simple model for the
diffusion noise, which varies quadratically with the variation of the dipole
moment, qualitatively reproduces the measured noise spectrum, and the estimate
of the noise spectral density is in accord with measured values.Comment: 8 pages, 6 figure
Технология проведения капитального ремонта магистрального газопровода "Нижневартовский газоперерабатывающий завод-Парабель"
Объектом исследования является магистрального газопровода "Нижневартовский газоперерабатывающий завод-Парабель".
Цель работы: изучение методов капитального ремонта магистрального газопровода.
В процессе исследования проводились расчет толщины стенки газопровода, определение пропускной способности. Рассмотрены вопросы разработки траншеи, прокладки, монтажа газопровода, проведение пневматических испытаний. . Проведены мероприятия по охране труда и безопасности строительства, охране окружающей среды.The object of research is the main gas pipeline "Nizhnevartovsk gas processing plant-Parabel".
The purpose of the work: to study the methods of capital repairs of the main gas pipeline.
In the course of the study, the calculation of the wall thickness of the gas pipeline and the determination of the throughput capacity were carried out. The issues of trench development, gas pipeline laying, installation, and pneumatic testing are considered. . Measures on labor protection and construction safety, environmental protection were carried out
The Molecular Line Opacity of MgH in Cool Stellar Atmospheres
A new, complete, theoretical rotational and vibrational line list for the A-X
electronic transition in MgH is presented. The list includes transition
energies and oscillator strengths for all possible allowed transitions and was
computed using the best available theoretical potential energies and dipole
transition moment function with the former adjusted to account for experimental
data. The A-X line list, as well as new line lists for the B'-X and the X-X
(pure rovibrational) transitions, were included in comprehensive stellar
atmosphere models for M, L, and T dwarfs and solar-type stars. The resulting
spectra, when compared to models lacking MgH, show that MgH provides
significant opacity in the visible between 4400 and 5600 Angstrom. Further,
comparison of the spectra obtained with the current line list to spectra
obtained using the line list constructed by Kurucz (1993) show that the Kurucz
list significantly overestimates the opacity due to MgH particularly for the
bands near 5150 and 4800 Angstrom with the discrepancy increasing with
decreasing effective temperature.Comment: 10 pages, 4 figures, 3 table
Spiral Chain O4 Form of Dense Oxygen
Oxygen is in many ways a unique element: the only known diatomic molecular
magnet and the capability of stabilization of the hitherto unexpected O8
cluster structure in its solid form at high pressure. Molecular dissociations
upon compression as one of the fundamental problems were reported for other
diatomic solids (e.g., H2, I2, Br2, and N2), but it remains elusive for solid
oxygen, making oxygen an intractable system. We here report the theoretical
prediction on the dissociation of molecular oxygen into a polymeric spiral
chain O4 structure (\theta-O4) by using first-principles calypso method on
crystal structure prediction. The \theta-O4 stabilizes above 2 TPa and has been
observed as the third high pressure phase of sulfur (S-III). We find that the
molecular O8 phase remains extremely stable in a large pressure range of 0.008
- 2 TPa, whose breakdown is driven by the pressure-induced instability of a
transverse acoustic phonon mode at zone boundary, leading to the ultimate
formation of \theta-O4. Remarkably, stabilization of \theta-O4 turns oxygen
from a superconductor into an insulator with a wide band gap (approximately 5.9
eV) originating from the sp3-like hybridized orbitals of oxygen and the
localization of valence electrons. (This is a pre-print version of the
following article: Li Zhu et al, Spiral chain O4 form of dense oxygen, Proc.
Natl. Acad. Sci. U.S.A. (2011), doi: 10.1073/pnas.1119375109, which has been
published online at http://www.pnas.org/content/early/2011/12/27/1119375109 .)Comment: 13 apages, 3 figure
Stability of tryptophan during food processing and storage: 1. Comparative losses of tryptophan, lysine and methionine in different model systems
1. The stability of tryptophan was evaluated in several different food model systems using a chemical method (high pressure liquid chromatography after alkaline-hydrolysis) and rat assays. Losses of tryptophan were compared with the losses of lysine and methionine. 2. Whey proteins stored in the presence of oxidizing lipids showed large losses of lysine and extensive methionine oxidation but only minor losses of tryptophan as measured chemically. The observed decrease in bioavailable tryptophan was explained by a lower protein digestibility. 3. Casein treated with hydrogen peroxide to oxidize all methionine to methionine sulphoxide showed a 9% loss in bioavailable tryptophan. 4. When casein was reacted with caffeic acid at pH 7 in the presence of monophenol monooxygenase (tyrosinase; EC 1.14.18.l), no chemical loss of tryptophan occurred, although fluorodinitrobenzene-reactive lysine fell by 23%. Tryptophan bioavailability fell IS%, partly due to an 8% reduction in protein digestibility. 5. Alkali-treated casein (0.15 M-sodium hydroxide, 80°,4 h) did not support rat growth. Chemically-determined tryptophan, available tryptophan and true nitrogen digestibility fell 10, 46 and 23% respectively. Racemization of tryptophan was found to be 10% (D/(D+L)). 6. In whole-milk powder, which had undergone ‘early' or ‘advanced' Maillard reactions, tryptophan, determined chemically or in rat assays, was virtually unchanged. Extensive lysine losses occurred. 7. It was concluded that losses of tryptophan during food processing and storage are small and of only minor nutritional importance, especially when compared with much larger losses of lysine and the more extensive oxidation of methionin
Strengthening Competence of Therapists-in-Training in the Treatment of Health Anxiety (Hypochondriasis): Validation of the Assessment of Core CBT Skills (ACCS)
Although the observation and assessment of psychotherapeutic competences is central to training, supervision, patient care, quality control, and life‐long practice, structured instruments are used only occasionally. In the current study, an observation‐based tool for the Assessment of Core CBT Skills (ACCS) was translated into German and adapted, and its psychometric properties were pilot evaluated. Competence of therapists‐in‐training was assessed in a random sample of n = 30 videos on cognitive‐behavioral therapy including patients diagnosed with hypochondriasis. Two of three raters independently assessed the competences demonstrated in the entire, active treatment sessions (n = 60). In our sample, internal consistency was excellent, and interrater reliability was good. Convergent validity (Cognitive Therapy Scale) and discriminant validity (Helping Alliance Questionnaire) were within the expected ranges. The ACCS total score did not significantly predict the reduction of symptoms of hypochondriasis, and a one‐factorial structure of the instrument was found. By providing multiple opportunities for feedback, self‐reflection and supervision, the ACCS may complement current tools for the assessment of psychotherapeutic competences and importantly, support competence‐based training and supervision
The Molecular Continuum Opacity of MgH in Cool Stellar Atmospheres
The opacity due to photodissociation of 24MgH is investigated in the
atmospheres of cool stars. The lowest two electronic transitions A 2Pi -- X
2Sigma+ and B' 2Sigma+ -- X 2 Sigma+ are considered where the cross sections
for the latter were published previously (Weck, Stancil, & Kirby 2002) while
the former are presented in this work. Model atmospheres calculated with the
PHOENIX code are used to investigate the effect of the photodissociation
opacity on spectra of cool stars. The A -- X photodissociation cross sections
are obtained using a combination of ab initio and experimentally derived
potential curves and dipole transition moments. Partial cross sections have
been evaluated over the accessible wavelength range 1770-4560 Angstrom for all
rotational transitions from the vibrational levels v''=0-11. Assuming a
Boltzmann distribution of the rovibrational levels of the X 2Sigma+ state, LTE
photodissociation cross sections are presented for temperatures between 1000
and 5000 K. Shape resonances, arising from rotational predissociation of
quasi-bound levels of the A 2Pi state near threshold, characterize the LTE
photodissociation cross sections. A sum rule is proposed as a check on the
accuracy of the photodissociation calculations.Comment: 9 pages, 8 figure
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