1,756 research outputs found
Energy, Society and the Global System: Towards an Ecological Model of African Underdevelopment
Subdynamics as a mechanism for objective description
The relationship between microsystems and macrosystems is considered in the
context of quantum field formulation of statistical mechanics: it is argued
that problems on foundations of quantum mechanics can be solved relying on this
relationship. This discussion requires some improvement of non-equilibrium
statistical mechanics that is briefly presented.Comment: latex, 15 pages. Paper submitted to Proc. Conference "Mysteries,
Puzzles And Paradoxes In Quantum Mechanics, Workshop on Entanglement And
Decoherence, Palazzo Feltrinelli, Gargnano, Garda Lake, Italy, 20-25
September, 199
On The Importance Of The Interclump Medium For Superionization: O VI Formation In The Wind Of Zeta Puppis
We have studied superionization and X-ray line formation in the spectra of zeta Pup using our new stellar atmosphere code (XCMFGEN) that can be used to simultaneously analyze optical, UV, and X-ray observations. Here, we present results on the formation of the O VI lambda lambda 1032, 1038 doublet. Our simulations, supported by simple theoretical calculations, show that clumped wind models that assume void in the interclump space cannot reproduce the observed O vi profiles. However, enough O vi can be produced if the voids are filled by a low-density gas. The recombination of O vi is very efficient in the dense material, but in the tenuous interclump region an observable amount of O vi can be maintained. We also find that different UV resonance lines are sensitive to different density regimes in z Pup: C IV is almost exclusively formed within the densest regions, while the majority of O vi resides between clumps. N v is an intermediate case, with contributions from both the tenuous gas and clumps
Effect of NLTE model atmospheres on photometric amplitudes and phases of early B-type pulsating stars
We study all possible sources of inaccuracy in theoretical values of the
photometric observables, i.e. amplitude ratios and phase differences, of early
B-type main sequence pulsators. Here, we discuss effects of parameters coming
from both models of stellar atmospheres and linear nonadiabatic theory of
stellar pulsation. In particular, we evaluate for the first time the effect of
the departure from the LTE approximation. The atmospheric input comes from
line-blanketed, LTE and NLTE plane-parallel, hydrostatic models. To compute the
limb-darkening coefficients for NLTE models, we use the Least-Square Method
taking into account the accuracy of the flux conservation. We present effects
of NLTE atmospheres, chemical composition and opacities on theoretical values
of the photometric observables of early B-type pulsators. To this end, we
compute tables with the passband fluxes, flux derivatives over effective
temperature and gravity as well as the non-linear limb-darkening coefficients
in 12 most often used passbands, i.e. in the Str\"omgern system, , and in
the Johnson-Cousins-Glass system, . We make these tables public
available at the Wroc{\l}aw HELAS Web page, http://helas.astro.uni.wroc.pl.Comment: 13 pages, 2 tables, 17 figues submitted to A&
Complex asteroseismology of the Slowly Pulsating B-type star HD74560
We present the results of complex seismic modelling of the Slowly Pulsating
B-type star HD74560. The star pulsates in five frequencies detected in
photometric observations. For all these frequencies, we identify the mode
degree, . For two of them, found also in spectroscopic data, we are able
to derived the empirical values of the complex nonadiabatic parameter . We
test effects of chemical composition and opacity data. Our results show that
the properties of seismic models of SPB stars differ significantly from those
of the more massive Cephei stars.Comment: 4 pages, 2 figures, conference proceedings, to appear in ASS
Incoherent dynamics in neutron-matter interaction
Coherent and incoherent neutron-matter interaction is studied inside a
recently introduced approach to subdynamics of a macrosystem. The equation
describing the interaction is of the Lindblad type and using the Fermi
pseudopotential we show that the commutator term is an optical potential
leading to well-known relations in neutron optics. The other terms, usually
ignored in optical descriptions and linked to the dynamic structure function of
the medium, give an incoherent contribution to the dynamics, which keeps
diffuse scattering and attenuation of the coherent beam into account, thus
warranting fulfilment of the optical theorem. The relevance of this analysis to
experiments in neutron interferometry is briefly discussed.Comment: 15 pages, revtex, no figures, to appear in Phys. Rev.
Dynamical Semigroup Description of Coherent and Incoherent Particle-Matter Interaction
The meaning of statistical experiments with single microsystems in quantum
mechanics is discussed and a general model in the framework of non-relativistic
quantum field theory is proposed, to describe both coherent and incoherent
interaction of a single microsystem with matter. Compactly developing the
calculations with superoperators, it is shown that the introduction of a time
scale, linked to irreversibility of the reduced dynamics, directly leads to a
dynamical semigroup expressed in terms of quantities typical of scattering
theory. Its generator consists of two terms, the first linked to a coherent
wavelike behaviour, the second related to an interaction having a measuring
character, possibly connected to events the microsystem produces propagating
inside matter. In case these events breed a measurement, an explicit
realization of some concepts of modern quantum mechanics ("effects" and
"operations") arises. The relevance of this description to a recent debate
questioning the validity of ordinary quantum mechanics to account for such
experimental situations as, e.g., neutron-interferometry, is briefly discussed.Comment: 22 pages, latex, no figure
A NLTE model atmosphere analysis of the pulsating sdO star SDSS J1600+0748
We started a program to construct several grids of suitable model atmospheres
and synthetic spectra for hot subdwarf O stars computed, for comparative
purposes, in LTE, NLTE, with and without metals. For the moment, we use our
grids to perform fits on our spectrum of SDSS J160043.6+074802.9 (J1600+0748
for short), this unique pulsating sdO star. Our best fit is currently obtained
with NLTE model atmospheres including carbon, nitrogen and oxygen in solar
abundances, which leads to the following parameters for SDSS J1600+0748 : Teff
= 69 060 +/- 2080 K, log g = 6.00 +/- 0.09 and log N(He)/N(H) = -0.61 +/- 0.06.
Improvements are needed, however, particularly for fitting the available He II
lines. It is hoped that the inclusion of Fe will help remedy the situation.Comment: 4 pages, 4 figures, accepted in Astrophysics and Space Science
(24/02/2010), Special issue Hot sudbwarf star
The O-type eclipsing binary SZ Cam revisited
We analyse new spectra of the multiple system SZ Cam because previous studies
found different values of the primary radial velocity amplitude. The older
solutions of light curves also have different ratios of secondary to primary
luminosity as inferred from the observed equivalent widths of spectral lines.
We therefore reanalyse the light curves of the eclipsing pair. Only the light
curve derived by Wesselink has a solution that agrees with the observed
equivalent width ratio. The resulting parameters of the binary are discussed.
Masses of and M, and radii and
R are derived. We point out that radial velocities measured
with the CCF method can be misleading when the method is applied to multiple
systems with complex line blends. New radial velocities are also obtained for
the visual component ADS 2984 A (HD 25639).Comment: Astronomy and Astrophysics, accepte
SUMO monoclonal antibodies vary in sensitivity, specificity, and ability to detect types of SUMO conjugate
Monoclonal antibodies (MAb) to members of the Small Ubiquitin-like modifier (SUMO) family are essential tools in the study of cellular SUMOylation. However, many anti-SUMO MAbs are poorly validated, and antibody matching to detection format is without an evidence base. Here we test the specificity and sensitivity of twenty-four anti-SUMO MAbs towards monomeric and polymeric SUMO1-4 in dot-blots, immunoblots, immunofluorescence and immunoprecipitation. We find substantial variability between SUMO MAbs for different conjugation states, for detecting increased SUMOylation in response to thirteen different stress agents, and as enrichment reagents for SUMOylated RanGAP1 or KAP1. All four anti-SUMO4 monoclonal antibodies tested cross-reacted wit SUMO2/3, and several SUMO2/3 monoclonal antibodies cross-reacted with SUMO4. These data characterize the specificity of twenty-four anti-SUMO antibodies across commonly used assays, creating an enabling resource for the SUMO research community
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