3,608 research outputs found
The fate of non-trivial entanglement under gravitational collapse
We analyse the evolution of the entanglement of a non-trivial initial quantum
field state (which, for simplicity, has been taken to be a bipartite state made
out of vacuum and the first excited state) when it undergoes a gravitational
collapse. We carry out this analysis by generalising the tools developed to
study entanglement behaviour in stationary scenarios and making them suitable
to deal with dynamical spacetimes. We also discuss what kind of problems can be
tackled using the formalism spelled out here as well as single out future
avenues of research.Comment: 9 pages, 2 figures. v2: Added Journal reference and small changes to
match published versio
Echo of the Quantum Bounce
We identify a signature of quantum gravitational effects that survives from
the early universe to the current era: Fluctuations of quantum fields as seen
by comoving observers are significantly influenced by the history of the early
universe. In particular we show how the existence (or not) of a quantum bounce
leaves a trace in the background quantum noise that is not damped and would be
non-negligible even nowadays. Furthermore, we estimate an upper bound for the
typical energy and length scales where quantum effects are relevant. We discuss
how this signature might be observed and therefore used to build falsifiability
tests of quantum gravity theories.Comment: Revtex4.1. 2 Figures. V2: Content extended and edited to match
published versio
Molecular mechanisms of cadherin function during cortical migration
During development of the cerebral cortex, different types of neurons migrate from distinct origins to create the different cortical layers and settle within them. Along their way, migrating neurons use cell adhesion molecules on their surface to interact with other cells that will play critical roles to ensure that migration is successful. Radially migrating projection neurons interact primarily with radial glia and Cajal-Retzius cells, whereas interneurons originating in the subpallium follow a longer, tangential route and encounter additional cellular substrates before reaching the cortex. Cell-cell adhesion is therefore essential for the correct migration of cortical neurons. Several members of the cadherin superfamily of cell adhesion proteins, which mediate cellular interactions through calcium-dependent, mostly homophilic binding, have been shown to play important roles during neuronal migration of both projection neurons and interneurons. Although several classical cadherins and protocadherins are involved in this process, the most prominent is CDH2. This mini review will explore the cellular and molecular mechanisms underpinning cadherin function during cortical migration, including recent advances in our understanding of the control of adhesive strength through regulation of cadherin surface levels.
Keywords: cerebral cortex, neuron, migration, cell surface, adhesion molecules, CDH2, molecular mechanis
The Quantum Echo of the Early Universe
We show that the fluctuations of quantum fields as seen by late comoving
observers are significantly influenced by the history of the early Universe,
and therefore they transmit information about the nature of spacetime in
timescales when quantum gravitational effects were non-negligible. We discuss
how this may be observable even nowadays, and thus used to build falsifiability
tests of quantum gravity theories.Comment: 3 pages. 2 Figures. Proceedings Theory Canada 9. Published in
Canadian Journal of Physics.
(http://www.nrcresearchpress.com/doi/abs/10.1139/cjp-2014-0567
Violation of the strong Huygen's principle and timelike signals from the early Universe
We analyze the implications of the violations of the strong Huygens principle
in the transmission of information from the early universe to the current era
via massless fields. We show that much more information reaches us through
timelike channels (not mediated by real photons) than it is carried by rays of
light, which are usually regarded as the only carriers of information.Comment: 5 pages, 2 figures. RevTeX 4.1. V2: Updated to match published
version. Previous title "A glimpse of the early universe without real light"
modified to match Physical Review Letters published versio
Curtain Wall with Solar Preheating of Ventilation Air. Full Scale Experimental Assessment
Heating load in Commercial buildings is highly related with ventilation systems, while at the same time local discomfort in the vicinity of glass walls occurs due to overheating. In this paper, a novel double envelope curtain wall is presented, which extracts heat from the façade by means of a ventilated cavity which is then incorporated to the ventilation air intake. A substantial reduction of heating loads is achieved. Whenever solar gains are not sought, a bypass element allows the natural ventilation of this air cavity, acting as a ventilated façade. An integrated control system with embedded electronics and actuators allows for a smart control of the system. The system is designed for integration with existing rooftop ventilation systems. Design considerations are discussed, and the outcomes of a full-scale experiment conducted in Bilbao (Spain) along 2019 presented
Transmittance and Reflectance of an Imprinted Cholesteric Elastomer During a Segregation Process
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