1,999 research outputs found
Protoplanetary disks in the hostile environment of Carina
We report the first direct imaging of protoplanetary disks in the star-forming region of Carina, the most distant massive cluster in which disks have been imaged. Using the Atacama Large Millimeter/sub-millimeter Array (ALMA), the disks are observed around two young stellar objects (YSOs) that are embedded inside evaporating gaseous globules and exhibit jet activity. The disks have an average radius of 60 au and total masses of 30 and 50 . Given the measured masses, the minimum timescale required for planet formation (~1–2 Myr) and the average age of the Carina population (~1–4 Myr), it is plausible that young planets are present or their formation is currently ongoing in these disks. The non-detection of millimeter emission above the 4σ threshold () in the core of the massive cluster Trumpler 14, an area containing previously identified proplyd candidates, suggests evidence for rapid photo-evaporative disk destruction in the cluster's harsh radiation field. This would prevent the formation of giant gas planets in disks located in the cores of Carina's dense subclusters, whereas the majority of YSO disks in the wider Carina region remain unaffected by external photoevaporation
Effective theories of connections and curvature: abelian case
We introduce a notion of measuring scales for quantum abelian gauge systems.
At each measuring scale a finite dimensional affine space stores information
about the evaluation of the curvature on a discrete family of surfaces. Affine
maps from the spaces assigned to finer scales to those assigned to coarser
scales play the role of coarse graining maps. This structure induces a
continuum limit space which contains information regarding curvature evaluation
on all piecewise linear surfaces with boundary. The evaluation of holonomies
along loops is also encoded in the spaces introduced here; thus, our framework
is closely related to loop quantization and it allows us to discuss effective
theories in a sensible way. We develop basic elements of measure theory on the
introduced spaces which are essential for the applicability of the framework to
the construction of quantum abelian gauge theories.Comment: 39 page
Directed current due to broken time-space symmetry
We consider the classical dynamics of a particle in a one-dimensional
space-periodic potential U(X) = U(X+2\pi) under the influence of a
time-periodic space-homogeneous external field E(t)=E(t+T). If E(t) is neither
symmetric function of t nor antisymmetric under time shifts , an ensemble of trajectories with zero current at t=0 yields a nonzero
finite current as . We explain this effect using symmetry
considerations and perturbation theory. Finally we add dissipation (friction)
and demonstrate that the resulting set of attractors keeps the broken symmetry
property in the basins of attraction and leads to directed currents as well.Comment: 2 figure
Epitome de la vida y muerte de la Reyna Doña Berenguela, primogenita del Rey Don Alonso de Castilla, aclamado el noble
Copia digital. Valladolid : Junta de Castilla y León. Consejería de Cultura y Turismo, 2009-2010Errores de pag., de p. 79 retrocede a p. 70Grab. xil. de la InmaculadaContiene: Tratado apologetico en defensa de mayoria de la Reina Doña Bereguela y el derecho q tuvo a los reynos de Castilla, p. 169 -23
Mirror symmetry breaking through an internal degree of freedom leading to directional motion
We analyze here the minimal conditions for directional motion (net flow in
phase space) of a molecular motor placed on a mirror-symmetric environment and
driven by a center-symmetric and time-periodic force field. The complete
characterization of the deterministic limit of the dissipative dynamics of
several realizations of this minimal model, reveals a complex structure in the
phase diagram in parameter space, with intertwined regions of pinning (closed
orbits) and directional motion. This demonstrates that the mirror-symmetry
breaking which is needed for directional motion to occur, can operate through
an internal degree of freedom coupled to the translational one.Comment: Accepted for publication in Phys. Rev.
Multi-scale coordination of distinctive movement patterns during embodied interaction between adults with high-functioning autism and neurotypicals
Funding We acknowledge financial support from DGAPA-PAPIIT projects of the Universidad Nacional Autónoma de México: IA105017 (RF and LZ-F) and IA104717 (TF), Consejo Nacional de Ciencia y Tecnología (CONACyT) projects 167441 (RF and LZ-F), the scholarship 638215 to LZ-F granted by the CONACyT, the Newton Advanced Fellowship awarded to RF by the Academy of Medical Sciences, through the UK Government’s Newton, and the Marie Curie Intra-European Fellowship “SOCIAL BRAIN” awarded to BT. Acknowledgments We thank Charles Lenay and Dominique Aubert from the Université de Technologie de Compiègne for making the TACTOS hardware and software available to the University Hospital Cologne, and for providing technical support. LZ-F would like to specially thank Jesús Naveja and Lilia Fonseca for interesting discussions. SUPPLEMENTARY MATERIAL The Supplementary Material for this article can be found online at: https://www.frontiersin.org/articles/10.3389/fpsyg.2018.02760/full#supplementary-materialPeer reviewedPublisher PD
- …