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Arousal regulates frequency tuning in primary auditory cortex.
Changes in arousal influence cortical sensory representations, but the synaptic mechanisms underlying arousal-dependent modulation of cortical processing are unclear. Here, we use 2-photon Ca2+ imaging in the auditory cortex of awake mice to show that heightened arousal, as indexed by pupil diameter, broadens frequency-tuned activity of layer 2/3 (L2/3) pyramidal cells. Sensory representations are less sparse, and the tuning of nearby cells more similar when arousal increases. Despite the reduction in selectivity, frequency discrimination by cell ensembles improves due to a decrease in shared trial-to-trial variability. In vivo whole-cell recordings reveal that mechanisms contributing to the effects of arousal on sensory representations include state-dependent modulation of membrane potential dynamics, spontaneous firing, and tone-evoked synaptic potentials. Surprisingly, changes in short-latency tone-evoked excitatory input cannot explain the effects of arousal on the broadness of frequency-tuned output. However, we show that arousal strongly modulates a slow tone-evoked suppression of recurrent excitation underlying lateral inhibition [H. K. Kato, S. K. Asinof, J. S. Isaacson, Neuron, 95, 412-423, (2017)]. This arousal-dependent "network suppression" gates the duration of tone-evoked responses and regulates the broadness of frequency tuning. Thus, arousal can shape tuning via modulation of indirect changes in recurrent network activity
Causality re-established
Causality never gained the status of a "law" or "principle" in physics. Some
recent literature even popularized the false idea that causality is a notion
that should be banned from theory. Such misconception relies on an alleged
universality of reversibility of laws of physics, based either on determinism
of classical theory, or on the multiverse interpretation of quantum theory, in
both cases motivated by mere interpretational requirements for realism of the
theory. Here, I will show that a properly defined unambiguous notion of
causality is a theorem of quantum theory, which is also a falsifiable
proposition of the theory. Such causality notion appeared in the literature
within the framework of operational probabilistic theories. It is a genuinely
theoretical notion, corresponding to establish a definite partial order among
events, in the same way as we do by using the future causal cone on Minkowski
space. The causality notion is logically completely independent of the
misidentified concept of "determinism", and, being a consequence of quantum
theory, is ubiquitous in physics. In addition, as classical theory can be
regarded as a restriction of quantum theory, causality holds also in the
classical case, although the determinism of the theory trivializes it. I then
conclude arguing that causality naturally establishes an arrow of time. This
implies that the scenario of the "Block Universe" and the connected "Past
Hypothesis" are incompatible with causality, and thus with quantum theory: they
both are doomed to remain mere interpretations and, as such, not falsifiable,
similar to the hypothesis of "super-determinism". This article is part of a
discussion meeting issue "Foundations of quantum mechanics and their impact on
contemporary society".Comment: Presented at the Royal Society of London, on 11/12/ 2017, at the
conference "Foundations of quantum mechanics and their impact on contemporary
society". To appear on Philosophical Transactions of the Royal Society
The Isaacson expansion in quantum cosmology
This paper is an application of the ideas of the Born-Oppenheimer (or
slow/fast) approximation in molecular physics and of the Isaacson (or
short-wave) approximation in classical gravity to the canonical quantization of
a perturbed minisuperspace model of the kind examined by Halliwell and Hawking.
Its aim is the clarification of the role of the semiclassical approximation and
the backreaction in such a model. Approximate solutions of the quantum model
are constructed which are not semiclassical, and semiclassical solutions in
which the quantum perturbations are highly excited.Comment: Revtex, 11 journal or 24 preprint pages. REPLACEMENT: A comment on
previous work by Dowker and Laflamme is corrected. Utah preprint
UU-REL-93/3/1
The mass-radius-luminosity-rotation relationship for M dwarf stars
NASA's future Transiting Exoplanet Survey Satellite (TESS) mission is expected to discover hundreds of terrestrial exoplanets orbiting around M dwarf stars, which will be nearby and amenable to detailed characterization. To accurately measure radii and equilibrium temperatures of these exoplanets, we need to know the host star properties, specifically mass, radius and luminosity, to equal accuracy. However, relationships for M dwarf stellar properties are poorly constrained, which leaves us unprepared to characterize exoplanets to be discovered by the TESS mission. The best way to determine relationships for M dwarf stars is to study mutually eclipsing binaries because the photometric and spectroscopic data empirically determine the physical parameters of the stars. We are conducting an on-going survey to measure infrared eclipses and individual spectra of carefully selected M dwarf eclipsing binary targets. We are using Mimir, a near-infrared wide-field imager, on the 72-inch Perkins Telescope near Flagstaff, Arizona, to determine the J, H, and K band magnitudes of the individual stars, and we are using Keck HIRES to measure the radial velocities of each component. Combining the observations, we determine the masses, radii and the semi-major axes of each component to an accuracy of 1%. We are also using measured parallaxes to determine the individual components' absolute infrared magnitudes and bolometric luminosities. The ultimate goal is to combine the measurements to determine the mass-radius-luminosity-rotation relationship for M dwarf stars. The relationship is critical for choosing the best TESS M dwarf exoplanets for detailed characterization.http://adsabs.harvard.edu/abs/2016AAS...22714221HPublished versio
A preliminary comparison of Landsat Thematic Mapper and SPOT-1 HRV multispectral data for estimating coniferous forest volume
Digital Landsat Thematic Mapper (TM) and Satellite Probatoire d'Observation de la Terre (SPOT) High Resolution Visible (HRV) images of coniferous forest canopies were compared in their relationship to forest wood volume using correlation and regression analyses. Significant inverse relationships were found between softwood volume and the spectral bands from both sensors (P less than 0.01). The highest correlations were between the log of softwood volume and the near-infrared bands (HRV band 3, r = -0.89; TM band 4, r = -0.83)
A Transiting Jupiter Analog
Decadal-long radial velocity surveys have recently started to discover
analogs to the most influential planet of our solar system, Jupiter. Detecting
and characterizing these worlds is expected to shape our understanding of our
uniqueness in the cosmos. Despite the great successes of recent transit
surveys, Jupiter analogs represent a terra incognita, owing to the strong
intrinsic bias of this method against long orbital periods. We here report on
the first validated transiting Jupiter analog, Kepler-167e (KOI-490.02),
discovered using Kepler archival photometry orbiting the K4-dwarf KIC-3239945.
With a radius of , a low orbital eccentricity
() and an equilibrium temperature of K,
Kepler-167e bears many of the basic hallmarks of Jupiter. Kepler-167e is
accompanied by three Super-Earths on compact orbits, which we also validate,
leaving a large cavity of transiting worlds around the habitable-zone. With two
transits and continuous photometric coverage, we are able to uniquely and
precisely measure the orbital period of this post snow-line planet
( d), paving the way for follow-up of this mag
target.Comment: 14 pages, 10 figures. Accepted to ApJ. Posteriors available at
https://github.com/CoolWorlds/Kepler-167-Posterior
The Quantum Gravitationally Induced Stress Tensor
We derive non-perturbative relations between the expectation value of the
invariant element in a homogeneous and isotropic state and the quantum
gravitationally induced pressure and energy density. By exploiting previously
obtained bounds for the maximum possible growth of perturbative corrections to
a locally de Sitter background we show that the two loop result dominates all
higher orders. We also show that the quantum gravitational slowing of inflation
becomes non-perturbatively strong earlier than previously expected.Comment: 13 pages, LaTeX 2 epsilo
The Lick-Carnegie Survey: A New Two-Planet System Around the Star HD 207832
Keck/HIRES precision radial velocities of HD 207832 indicate the presence of
two Jovian-type planetary companions in Keplerian orbits around this G star.
The planets have minimum masses of 0.56 and 0.73 Jupiter-masses with orbital
periods of ~162 and ~1156 days, and eccentricities of 0.13 and 0.27,
respectively. Stromgren b and y photometry reveals a clear stellar rotation
signature of the host star with a period of 17.8 days, well separated from the
period of the radial velocity variations, reinforcing their Keplerian origin.
The values of the semimajor axes of the planets suggest that these objects have
migrated from the region of giant planet formation to closer orbits. In order
to examine the possibility of the existence of additional (small) planets in
the system, we studied the orbital stability of hypothetical terrestrial-sized
objects in the region between the two planets and interior to the orbit of the
inner body. Results indicated that stable orbits exist only in a small region
interior to planet b. However, the current observational data offer no evidence
for the existence of additional objects in this system.Comment: 23 pages, 4 figures, 5 tables, accepted for publication in Ap
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