15,169 research outputs found
Hyperonic crystallization in hadronic matter
Published in Hadrons, Nuclei and Applications, World Scientific, Singapore,
Proc.of the Conference Bologna2000. Structure of the Nucleus at the Dawn of the
Century, G. Bonsignori, M. Bruno, A. Ventura, D. Vretenar Editors, pag. 319.Comment: 4 pages, 2figure
The ages of very cool hydrogen-rich white dwarfs
The evolution of white dwarfs is essentially a cooling process that depends
primarily on the energy stored in their degenerate cores and on the
transparency of their envelopes. In this paper we compute accurate cooling
sequences for carbon-oxygen white dwarfs with hydrogen dominated atmospheres
for the full range of masses of interest. For this purpose we use the most
accurate available physical inputs for both the equation of state and opacities
of the envelope and for the thermodynamic quantities of the degenerate core. We
also investigate the role of the latent heat in the computed cooling sequences.
We present separately cooling sequences in which the effects of phase
separation of the carbon-oxygen binary mixture upon crystallization have been
neglected, and the delay introduced in the cooling times when this mechanism is
properly taken into account, in order to compare our results with other
published cooling sequences which do not include a treatment of this
phenomenon. We find that the cooling ages of very cool white dwarfs with pure
hydrogen atmospheres have been systematically underestimated by roughly 1.5 Gyr
at log(L/Lo)=-4.5 for an otherwise typical 0.6 Mo white dwarf, when phase
separation is neglected. If phase separation of the binary mixture is included
then the cooling ages are further increased by roughly 10%. Cooling tracks and
cooling isochrones in several color-magnitude diagrams are presented as well.Comment: 8 Pages; ApJ, accepted for publicatio
Mujeres, vida cotidiana y espacios públicos en la región metropolitana de Barcelona. El caso de Ca n’Anglada de Terrassa
Women, daily life and public spaces in Barcelona’s Metropolitan Area: a case-study of the Ca N’Anglada district of Terrassa. The aimof this article is to discuss the daily use of public space by women in a working class neighbourhood, located within the Barcelona Metropolitan Area: Ca N’Anglada, in the city of Terrassa. Firstly we analyse the concept of public space from a gender perspective secondly we present the research methodology as well as the historical and social context of the case-study. The third part focuses on the empirical analysis of women’s daily life and of the use of public spaces in the neighbourhood. Finally, we draw some conclusions and put forth a number of proposals. The research presented in the article made use of qualitative methods, namely participant and non-participant observation, and in-depth interviews
Sharp crossover from composite fermionization to phase separation in mesoscopic mixtures of ultracold bosons
We show that a two-component mixture of a few repulsively interacting
ultracold atoms in a one-dimensional trap possesses very different quantum
regimes and that the crossover between them can be induced by tuning the
interactions in one of the species. In the composite fermionization regime,
where the interactions between both components are large, none of the species
show large occupation of any natural orbital. Our results show that by
increasing the interaction in one of the species, one can reach the
phase-separated regime. In this regime, the weakly interacting component stays
at the center of the trap and becomes almost fully phase coherent, while the
strongly interacting component is displaced to the edges of the trap. The
crossover is sharp, as observed in the in the energy and the in the largest
occupation of a natural orbital of the weakly interacting species. Such a
transition is a purely mesoscopic effect which disappears for large atom
numbers.Comment: 5 pages, 3 figure
The massive multiple system HD 64315
The O6 Vn star HD 64315 is believed to belong to the star-forming region
known as NGC 2467, but previous distance estimates do not support this
association. We explore the multiple nature of this star with the aim of
determining its distance, and understanding its connection to NGC 2467. A total
of 52 high-resolution spectra have been gathered over a decade. We use their
analysis, in combination with the photometric data from All Sky Automated
Survey and Hipparcos catalogues, to conclude that HD 64315 is composed of at
least two spectroscopic binaries, one of which is an eclipsing binary. HD 64315
contains two binary systems, one of which is an eclipsing binary. The two
binaries are separated by 0.09 arcsec (or 500 AU) if the most likely distance
to the system, around 5 kpc, is considered. The presence of fainter companions
is not excluded by current observations. The non-eclipsing binary (HD 64315
AaAb) has a period of 2.70962901+/-0.00000021 d. Its components are hotter than
those of the eclipsing binary, and dominate the appearance of the system. The
eclipsing binary (HD 64315 BaBb) has a shorter period of 1.0189569+/-0.0000008
d. We derive masses of 14.6+-2.3 M for both components of the BaBb
system. They are almost identical; both stars are overfilling their respective
Roche lobes, and share a common envelope in an overcontact configuration. The
non-eclipsing binary is a detached system composed of two stars with spectral
types around O6 V with minimum masses of 10.8 M and 10.2 M, and
likely masses aprox. 30 M. HD 64315 provides a cautionary tale about
high-mass star isolation and multiplicity. Its total mass is likely above 90
M,but it seems to have formed without an accompanying cluster. It
contains one the most massive overcontact binaries known, a likely merger
progenitor in a very wide multiple system.Comment: 14 pages, 13 figures, 8 Table
STAR:a simple TAL effector assembly reaction using isothermal assembly
Transcription activator-like effectors (TALEs) contain modular programmable DNA binding domains. Fusing TALEs with effector domains creates synthetic transcription factors (TALE-TFs) or nucleases (TALENs), enabling precise gene manipulations. The construction of TALEs remains challenging due to their repetitive sequences. Here we report a simple TALE assembly reaction (STAR) that enables individual laboratories to generate multiple TALEs in a facile manner. STAR uses an isothermal assembly (‘Gibson assembly’) that is labour- and cost-effective, accessible, rapid and scalable. A small 68-part fragment library is employed, and the specific TALE repeat sequence is generated within ~8 hours. Sequence-verified TALENs or TALE-TF plasmids targeting 17 bp target sequences can be produced within three days, without the need for stepwise intermediate plasmid production. We demonstrate the utility of STAR through production of functional TALE-TFs capable of activating human SOX2 expression. STAR addresses some of the shortcomings of existing Golden Gate or solid-phase assembly protocols and enables routine production of TALE-TFs that will complement emerging CRISPR/Cas9-based reagents across diverse applications in mammalian stem cell and synthetic biology
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