1,078 research outputs found
Systematic NLTE study of the -2.6 < [Fe/H] < 0.2 F and G dwarfs in the solar neighbourhood. I. Stellar atmosphere parameters
We present atmospheric parameters for 51 nearby FG dwarfs uniformly
distributed over the -2.60 < [Fe/H] < +0.20 metallicity range that is suitable
for the Galactic chemical evolution research. Lines of iron, Fe I and Fe II,
were used to derive a homogeneous set of effective temperatures, surface
gravities, iron abundances, and microturbulence velocities. We used
high-resolution (R>60000) Shane/Hamilton and CFHT/ESPaDOnS observed spectra and
non-local thermodynamic equilibrium (NLTE) line formation for Fe I and Fe II in
the classical 1D model atmospheres. The spectroscopic method was tested with
the 20 benchmark stars, for which there are multiple measurements of the
infrared flux method (IRFM) Teff and their Hipparcos parallax error is < 10%.
We found NLTE abundances from lines of Fe I and Fe II to be consistent within
0.06 dex for every benchmark star, when applying a scaling factor of S_H = 0.5
to the Drawinian rates of inelastic Fe+H collisions. The obtained atmospheric
parameters were checked for each program star by comparing its position in the
log g-Teff plane with the theoretical evolutionary track in the Yi et al.
(2004) grid. Our final effective temperatures lie in between the T_IRFM scales
of Alonso et al. (1996) and Casagrande et al. (2011), with a mean difference of
+46 K and -51 K, respectively. NLTE leads to higher surface gravity compared
with that for LTE. The shift in log g is smaller than 0.1 dex for stars with
either [Fe/H] > -0.75, or Teff 4.20. NLTE analysis is
crucial for the VMP turn-off and subgiant stars, for which the shift in log g
between NLTE and LTE can be up to 0.5 dex. The obtained atmospheric parameters
will be used in the forthcoming papers to determine NLTE abundances of
important astrophysical elements from lithium to europium and to improve
observational constraints on the chemo-dynamical models of the Galaxy
evolution.Comment: 18 pages, 14 figures, accepted for publication in Ap
Molecular confirmation of species status for the allopolyploid cotton species, Gossypium ekmanianum Wittmack.
Understanding the relationship between domesticated crop species and their wild relatives is paramount to germplasm maintenance and the utilization of wild relatives in breeding programs. Recently, Gossypium ekmanianum was resurrected as an independent species based on morphological analysis of specimens obtained from the Dominican Republic, where the original type specimen was collected. The molecular data presented here support the recognition of G. ekmanianum Wittmack as a distinct species that is phylogenetically close to G. hirsutum L. Analyses of chloroplast DNA data reveal species-specific, indel polymorphisms that unambiguously distinguish G. ekmanianum samples from other polyploid congeners. Furthermore, analysis of accessions that originated from the Dominican Republic demonstrate the cryptic inclusion of this sister taxon within the US National Plant Germplasm System, a germplasm collection maintained for diversity preservation and future breeding resources. The data presented here indicate that ‘‘wild’’ G. hirsutum accessions may include the closely related G. ekmanianum, and provide a method to easily distinguish the two.Fil: Grover, C. E.. University of Iowa; Estados UnidosFil: Zhu, X.. Nantong University; ChinaFil: Grupp, K. K.. University Of Iowa; Estados UnidosFil: Jareczek, J. J.. University of Iowa; Estados UnidosFil: J. P. Gallagher. University of Iowa; Estados UnidosFil: Szadkowski, E.. University of Iowa; Estados UnidosFil: Seijo, Jose Guillermo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Nordeste. Instituto de Botánica del Nordeste (i); Argentina. Universidad Nacional del Nordeste. Facultad de Ciencias Exactas Naturales y Agrimensura; ArgentinaFil: Wendel, J. F.. University of Iowa; Estados Unido
Mounting, metrology and verification of Euclid near infrared spectro-photometer optical assembly NI-OA
Observation of enhanced transmission for s-polarized light through a subwavelength slit
Enhanced optical transmission (EOT) through subwavelength apertures is
usually obtained for p-polarized light. The present study experimentally
investigates EOT for s-polarized light. A subwavelength slit surrounded on each
side by periodic grooves has been fabricated in a gold film and covered by a
thin dielectric layer. The excitation of s-polarized dielectric waveguide modes
inside the dielectric film strongly increases the s-polarized transmission.
Transmission measurements are compared with a coupled mode model and show good
qualitative agreement. Adding a waveguide can improve light transmission
through subwavelength apertures, as both s and p-polarization can be
efficiently transmitted.Comment: 11 pages, 3 figures, submitted to Applied Physics Letter
Statistical equilibrium of silicon in the solar atmosphere
The statistical equilibrium of neutral and ionised silicon in the solar
photosphere is investigated. Line formation is discussed and the solar silicon
abundance determined. High-resolution solar spectra were used to determine
solar values by comparison with Si line synthesis
based on LTE and NLTE level populations. The results will be used in a
forthcoming paper for differential abundance analyses of metal-poor stars. A
detailed analysis of silicon line spectra leads to setting up realistic model
atoms, which are exposed to interactions in plane-parallel solar atmospheric
models. The resulting departure coefficients are entered into a line-by-line
analysis of the visible and near-infrared solar silicon spectrum. The
statistical equilibrium of \ion{Si}{i} turns out to depend marginally on
bound-free interaction processes, both radiative and collisional. Bound-bound
interaction processes do not play a significant role either, except for
hydrogen collisions, which have to be chosen adequately for fitting the cores
of the near-infrared lines. Except for some near-infrared lines, the NLTE
influence on the abundances is weak. Taking the deviations from LTE in silicon
into account, it is possible to calculate the ionisation equilibrium from
neutral and ionised lines. The solar abundance based on the experimental
-values of Garz corrected for the Becker et al.'s measurement is . Combined with an extended line sample with selected NIST -values, the
solar abundance is , with a nearly perfect ionisation
equilibrium of \Delta\log\epsilon_\odot(\ion{Si}{ii}/\ion{Si}{i}) = -0.01.Comment: 13pages 10 figures. A&A acceptte
Theory of extraordinary optical transmission through subwavelength hole arrays
We present a fully three-dimensional theoretical study of the extraordinary
transmission of light through subwavelength hole arrays in optically thick
metal films. Good agreement is obtained with experimental data. An analytical
minimal model is also developed, which conclusively shows that the enhancement
of transmission is due to tunneling through surface plasmons formed on each
metal-dielectric interfaces. Different regimes of tunneling (resonant through a
''surface plasmon molecule", or sequential through two isolated surface
plasmons) are found depending on the geometrical parameters defining the
system.Comment: 4 pages, 4 figure
Development of High Technologies as an Indicator of Modern Industry in the Eu
The article tries to classify the EU states in terms of the advancement of structural changes in their industries on the basis of the increase in the share of advanced technologies in total industrial production, labour, added value, and surplus. In the times of the knowledge-based economy the ability to produce high-tech goods, the demand for which is growing much faster than for traditional goods, indicates the level of modernity of industry. The dynamic growth of the demand for knowledge-based high-tech goods results from the evolution of consumer habits, which are predominantly driven by educated and rich societies who demand that their sophisticated needs met. An important role in stimulating this demand is played by modern media as they instantly deliver information on the latest technical developments and are very efficient in transferring patterns of consumerism. The ability to adapt the structure of production to the needs of the market is crucial in defining a state's position in the international exchange of goods. This is due to the fact that the national technology is tightly interwoven with export abilities
Differences in Anatomy and Kinematics in Asian and Caucasian TKA Patients: Influence on Implant Positioning and Subsequent Loading Conditions in Mobile Bearing Knees
The objective of our study was to determine the mechanical stress conditions under tibiofemoral loading with an overlay of knee kinematics in deep flexion on two different mobile bearing designs in comparison to in vivo failure modes. This study investigates the seldom but severe complication of fatigue failure of polyethylene components at mobile bearing total knee arthroplasty designs. Assuming a combination of a floor-based lifestyle and tibial malrotation as a possible reason for a higher failure rate in Asian countries we developed a simplified finite element model considering a tibiofemoral roll-back angle of 22 degrees and the range of rotational motion of a clinically established floating platform design (e. motion FP) at a knee flexion angle of 120 degrees in order to compare our results to failure modes found in retrieved implants. Compared to the failure mode observed in the clinical retrievals the locations of the occurring stress maxima as well as the tensile stress distribution show analogies. From our observations, we conclude that the newly introduced finite element model with an overlay of deep knee flexion (lateral roll-back) and considerable internally rotated tibia implant positioning is an appropriate analysis for knee design optimizations and a suitable method to predict clinical failure modes
Electronic properties and Fermi surface of Ag(111) films deposited onto H-passivated Si(111)-(1x1) surfaces
Silver films were deposited at room temperature onto H-passivated Si(111)
surfaces. Their electronic properties have been analyzed by angle-resolved
photoelectron spectroscopy. Submonolayer films were semiconducting and the
onset of metallization was found at a Ag coverage of 0.6 monolayers. Two
surface states were observed at -point in the metallic films,
with binding energies of 0.1 and 0.35 eV. By measurements of photoelectron
angular distribution at the Fermi level in these films, a cross-sectional cut
of the Fermi surface was obtained. The Fermi vector determined along different
symmetry directions and the photoelectron lifetime of states at the Fermi level
are quite close to those expected for Ag single crystal. In spite of this
concordance, the Fermi surface reflects a sixfold symmetry rather than the
threefold symmetry of Ag single crystal. This behavior was attributed to the
fact that these Ag films are composed by two domains rotated 60.Comment: 9 pages, 8 figures, submitted to Physical Review
Practical guidelines for monitoring and management of coagulopathy following tisagenlecleucel CAR T-cell therapy
Cytokine release syndrome (CRS) is a systemic inflammatory response associated with chimeric antigen receptor T-cell (CAR-T) therapies. In severe cases, CRS can be associated with coagulopathy and hypofibrinogenemia. We present our global multicenter experience with CRS-associated coagulopathy after tisagenlecleucel therapy in 137 patients with relapsed or refractory B-cell acute lymphoblastic leukemia from the ELIANA and ENSIGN trials. These trials included clinical guidelines for fibrinogen replacement during CRS-associated coagulopathy. Hypofibrinogenemia requiring replacement was observed only in patients with severe CRS. A higher percentage of patients who required replacement were <10 years old, compared with those who did not require replacement. Twenty-three patients received replacement for hypofibrinogenemia (<1.5 g/L); 9 of them developed marked hypofibrinogenemia (<1 g/L). Very low fibrinogen levels (<1 g/L) were documented in patients before maximal CRS (n = 1), during maximal CRS (n = 7), and at CRS improvement (n = 1). Although hypofibrinogenemia was the most clinically significant coagulopathy, some patients also developed prolonged prothrombin time and activated partial thromboplastin time and increased international normalized ratio, further increasing the risk of bleeding. Hypofibrinogenemia was effectively managed using fibrinogen concentrate or cryoprecipitate replacement; severe (grade 4) bleeding events were rare (n = 2). CRS-associated coagulopathy with hypofibrinogenemia is manageable according to empiric guidelines of fibrinogen replacement for CAR-T trials. Fibrinogen concentrate should be used when cryoprecipitate is not reliably available. Monitoring fibrinogen levels in patients with moderate or severe CRS is essential for avoiding potentially fatal bleeding events
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