10,476 research outputs found
Coexistence of Antiferromagnetism and Superconductivity in Electron-doped High-Tc Superconductors
We present magnetotransport evidence for antiferromagnetism in films of the
electron-doped cuprates PrCeCuO. Our results show clear
signature of static antiferromagnetism up to optimal doping x=0.15, with a
quantum phase transition close to x=0.16, and a coexistence of static
antiferromagnetism and superconductivity for 0.12x0.15
Respiratory Muscle Aids in the Management of Neuromuscular Respiratory Impairment to Prevent Respiratory Failure and Need for Tracheostomy
Better safe than sorry: Risky function exploitation through safe optimization
Exploration-exploitation of functions, that is learning and optimizing a
mapping between inputs and expected outputs, is ubiquitous to many real world
situations. These situations sometimes require us to avoid certain outcomes at
all cost, for example because they are poisonous, harmful, or otherwise
dangerous. We test participants' behavior in scenarios in which they have to
find the optimum of a function while at the same time avoid outputs below a
certain threshold. In two experiments, we find that Safe-Optimization, a
Gaussian Process-based exploration-exploitation algorithm, describes
participants' behavior well and that participants seem to care firstly whether
a point is safe and then try to pick the optimal point from all such safe
points. This means that their trade-off between exploration and exploitation
can be seen as an intelligent, approximate, and homeostasis-driven strategy.Comment: 6 pages, submitted to Cognitive Science Conferenc
'Return to equilibrium' for weakly coupled quantum systems: a simple polymer expansion
Recently, several authors studied small quantum systems weakly coupled to
free boson or fermion fields at positive temperature. All the approaches we are
aware of employ complex deformations of Liouvillians or Mourre theory (the
infinitesimal version of the former). We present an approach based on polymer
expansions of statistical mechanics. Despite the fact that our approach is
elementary, our results are slightly sharper than those contained in the
literature up to now. We show that, whenever the small quantum system is known
to admit a Markov approximation (Pauli master equation \emph{aka} Lindblad
equation) in the weak coupling limit, and the Markov approximation is
exponentially mixing, then the weakly coupled system approaches a unique
invariant state that is perturbatively close to its Markov approximation.Comment: 23 pages, v2-->v3: Revised version: The explanatory section 1.7 has
changed and Section 3.2 has been made more explici
Analytic measures for quantification of arousal from spontaneous skin conductance fluctuations
AbstractAutonomic arousal is often indexed by spontaneous fluctuations in skin conductance. Here, we derive a simple measure of sympathetic arousal, using a convolution model of how sudomotor bursting causes fluctuations in skin conductivity. Under this model, the time-integral of measured conductance is proportional to the frequency and amplitude of sudomotor bursts. We demonstrate the validity of this measure in relation to finite impulse response models, and show that it is a better predictor of autonomic arousal, relative to conventional measures
On the resistivity at low temperatures in electron-doped cuprate superconductors
We measured the magnetoresistance as a function of temperature down to 20mK
and magnetic field for a set of underdoped PrCeCuO (x=0.12) thin films with
controlled oxygen content. This allows us to access the edge of the
superconducting dome on the underdoped side. The sheet resistance increases
with increasing oxygen content whereas the superconducting transition
temperature is steadily decreasing down to zero. Upon applying various magnetic
fields to suppress superconductivity we found that the sheet resistance
increases when the temperature is lowered. It saturates at very low
temperatures. These results, along with the magnetoresistance, cannot be
described in the context of zero temperature two dimensional
superconductor-to-insulator transition nor as a simple Kondo effect due to
scattering off spins in the copper-oxide planes. We conjecture that due to the
proximity to an antiferromagnetic phase magnetic droplets are induced. This
results in negative magnetoresistance and in an upturn in the resistivity.Comment: Accepted in Phys. Rev.
Spectral Properties of the Core and the VLBI-Jets of Cygnus A
We present a detailed VLBI study of the spectral properties of the inner core
region of the radio galaxy Cygnus A at 5 GHz, 15 GHz, 22 GHz, 43 GHz and 86
GHz. Our observations include an epoch using phase-referencing at 15 GHz and 22
GHz and the first successful VLBI observations of Cygnus A at 86 GHz. We find a
pronounced two-sided jet structure, with a steep spectrum along the jet and an
inverted spectrum towards the counter-jet. The inverted spectrum and the
frequency-dependent jet-to-counter-jet ratio suggest that the inner counter-jet
is covered by a circum-nuclear absorber as it is proposed by the unified
scheme.Comment: 2 pages, 2 figures, Proceedings of the 7th EVN Symposium held in
Toledo, Spain in October 2004, needs evn2004.cl
Differential Mass Evacuation Sampling Method for Measuring Refrigerant Charge in Round Tube Plate Fin Heat Exchangers (ASHRAE RP-1785)
Differential Mass Measurement Scale for Measuring Refrigerant Charge and Oil Retention of Round Tube Plate Fin Heat Exchangers (ASHRAE RP-1785)
During the product development process of split-system air-conditioning units, simulation models are widely used by manufacturers to predict equipment performance. Model-based development allows manufacturers to reduce the number of experiments prior to product launch, reducing product development cycle time and cost. However, the current models struggle to predict performance for reversible heat pump systems because of inaccurate predictions of refrigerant charge and oil retention. This is due to a lack of validation data for R410A charge models. This study provides high-quality reference data for refrigerant and oil charge measurements in residential fin-tube heat exchangers operating with R410A. This high-quality reference data will allow tuning of simulation models to improve charge prediction accuracy. As a result, the data will enable enhanced simulation model development with better charge and performance prediction capabilities, reducing product development cost for our industry. A key component, the Differential Mass Measurement Scale (DMMS) with 0.006% of relative accuracy of 49.9 kg tare weight of a heat exchanger test module, to implement this method is presented
The EVN view of the highly variable TeV active galaxy IC 310
Very-high-energy -ray observations of the active galaxy IC 310 with
the MAGIC telescopes have revealed fast variability with doubling time scales
of less than 4.8min. This implies that the emission region in IC 310 is smaller
than 20% of the gravitational radius of the central supermassive black hole
with a mass of , which poses serious questions on the
emission mechanism and classification of this enigmatic object. We report on
the first quasi-simultaneous multi-frequency VLBI observations of IC 310
conducted with the EVN. We find a blazar-like one-sided core-jet structure on
parsec scales, constraining the inclination angle to be less than but very small angles are excluded to limit the de-projected length
of the large-scale radio jet.Comment: 4 pages, proceedings of the 12th European VLBI Network Symposium and
Users Meeting - EVN 2014, 7-10 October 2014, Cagliari, Italy. Published
online in PoS, ID.10
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