2,532 research outputs found
Central Bank communication and monetary policy: a survey of theory and evidence
Over the last two decades, communication has become an increasingly important aspect of monetary policy. These real-world developments have spawned a huge new scholarly literature on central bank communication —mostly empirical, and almost all of it written in this decade. We survey this evergrowing literature. The evidence suggests that communication can be an important and powerful part of the central bank’s toolkit since it has the ability to move financial markets, to enhance the predictability of monetary policy decisions, and potentially to help achieve central banks’ macroeconomic objectives. However, the large variation in communication strategies across central banks suggests that a consensus has yet to emerge on what constitutes an optimal communication strategy. JEL Classification: E52, E58Central Bank, communication, monetary policy
Central Bank Communication and Monetary Policy: A Survey of Theory and Evidence
Over the last two decades, communication has become an increasingly important aspect of monetary policy. These real-world developments have spawned a huge new scholarly literature on central bank communication—mostly empirical, and almost all of it written in this decade. We survey this ever-growing literature. The evidence suggests that communication can be an important and powerful part of the central bank’s toolkit since it has the ability to move financial markets, to enhance the predictability of monetary policy decisions, and potentially to help achieve central banks’ macroeconomic objectives. However, the large variation in communication strategies across central banks suggests that a consensus has yet to emerge on what constitutes an optimal communication strategy.
Experimental Performance Evaluation of a High Speed Permanent Magnet Synchronous Motor and Drive for a Flywheel Application at Different Frequencies
This paper presents the results of an experimental performance characterization study of a high speed, permanent magnet motor/generator (M/G) and drive applied to a flywheel module. Unlike the conventional electric machine the flywheel M/G is not a separated unit; its stator and rotor are integrated into a flywheel assembly. The M/G rotor is mounted on a flywheel rotor, which is magnetically levitated and sealed within a vacuum chamber during the operation. Thus, it is not possible to test the M/G using direct load measurements with a dynamometer and torque transducer. Accordingly, a new in-situ testing method had to be developed. The paper describes a new flywheel M/G and drive performance evaluation technique, which allows the estimation of the losses, efficiency and power quality of the flywheel high speed permanent magnet M/G, while working in vacuum, over wide frequency and torque ranges. This method does not require any hardware modification nor any special addition to the test rig. This new measurement technique is useful for high-speed applications, when applying an external load is technically difficult
Interstellar Carbon in Translucent Sightlines
We report interstellar C II column densities or upper limits determined from
weak absorption of the 2325.4029 A intersystem transition observed in six
translucent sightlines with STIS. The sightlines sample a wide range of
interstellar characteristics including total-to-selective extinction, R_{V} =
2.6 - 5.1; average hydrogen density along the sightline, = 3 - 14
cm^{-3}; and fraction of H in molecular form, 0 - 40%. Four of the sightlines,
those toward HD 37021, HD 37061, HD 147888 and HD 207198, have interstellar
gas-phase abundances that are consistent with the diffuse sightline ratio of
161 +/- 17 carbon atoms in the gas per million hydrogen nuclei. We note that
while it has a gas-phase carbon abundance that is consistent with the other
sightlines, a large fraction of the C II toward HD 37061 is in an excited
state. The sightline toward HD 152590 has a measured interstellar gas-phase
carbon abundance that is well above the diffuse sightline average; the column
density of C in this sightline may be overestimated due to noise structure in
the data. Toward HD 27778 we find a 3 sigma abundance upper limit of <108 C
atoms in the gas per million H, a substantially enhanced depletion of C as
compared to the diffuse sightline value. The interstellar characteristics
toward HD 27778 are otherwise not extreme among the sample except for an
unusually large abundance of CO molecules in the gas.Comment: Accepted for publication in the Astrophysical Journa
Sampling-Based Robust Control of Autonomous Systems with Non-Gaussian Noise
Controllers for autonomous systems that operate in safetycritical settings must account for stochastic disturbances. Such disturbances are often modeled as process noise, and common assumptions are that the underlying distributions are known and/or Gaussian. In practice, however, these assumptions may be unrealistic and can lead to poor approximations of the true noise distribution. We present a novel planning method that does not rely on any explicit representation of the noise distributions. In particular, we address the problem of computing a controller that provides probabilistic guarantees on safely reaching a target. First, we abstract the continuous system into a discrete-state model that captures noise by probabilistic transitions between states. As a key contribution, we adapt tools from the scenario approach to compute probably approximately correct (PAC) bounds on these transition probabilities, based on a finite number of samples of the noise. We capture these bounds in the transition probability intervals of a socalled interval Markov decision process (iMDP). This iMDP is robust against uncertainty in the transition probabilities, and the tightness of the probability intervals can be controlled through the number of samples. We use state-of-the-art verification techniques to provide guarantees on the iMDP, and compute a controller for which these guarantees carry over to the autonomous system. Realistic benchmarks show the practical applicability of our method, even when the iMDP has millions of states or transitions.</p
Central Bank Communication and Monetary Policy: A Survey of Theory and Evidence
Over the last two decades, communication has become an increasingly important aspect of monetary policy. These real-world developments have spawned a huge new scholarly literature on central bank communication -- mostly empirical, and almost all of it written in this decade. We survey this ever-growing literature. The evidence suggests that communication can be an important and powerful part of the central bank's toolkit since it has the ability to move financial markets, to enhance the predictability of monetary policy decisions, and potentially to help achieve central banks' macroeconomic objectives. However, the large variation in communication strategies across central banks suggests that a consensus has yet to emerge on what constitutes an optimal communication strategy.
High resolution soft X-ray spectroscopy of the elliptical galaxy NGC 5044. Results from the reflection grating spectrometer on-board XMM-Newton
The results from an X-ray spectroscopic study of the giant elliptical galaxy
NGC5044 in the center of a galaxy group are presented. The line dominated soft
X-ray spectra (mainly Fe-L and O VIII Ly_a) from the diffuse gas are resolved
for the first time in this system with the Reflection Grating Spectrometers
on-board XMM-Newton and provide a strong constraint on the temperature
structure. The spectra integrated over 2' (\sim 20kpc) in full-width can be
described by a two temperature plasma model of 0.7keV and 1.1keV. Most of the
latter component is consistent with originating from off-center regions.
Compared to the isobaric cooling flow prediction, the observation shows a clear
cut-off below a temperature of 0.6 +-0.1keV. Furthermore, the Fe and O
abundances within the central 10--20kpc in radius are accurately measured to be
0.55+-0.05 and 0.25+-0.1 times the solar ratios, respectively. The observed
cut-off temperature of this galaxy and other central galaxies in galaxy groups
and clusters are compared with the scale of the galaxy and properties of the
surrounding intra-cluster medium. Based on this comparison, the origin of the
lack of predicted cool emission is discussed.Comment: Accepted for publication in Astronomy & Astrophysic
Enhancing Tc in field-doped Fullerenes by applying uniaxial stress
Capitalizing on the two-dimensional nature of superconductivity in
field-effect doped C60, we show that it should be possible to increase the
transition temperature Tc by applying uniaxial stress perpendicular to the gate
electrode. This method not only holds the promise of substantially enhancing Tc
(by about 30 K per GPa), but also provides a sensitive check of the current
understanding of superconductivity in the doped Fullerenes.Comment: 3 pages RevTe
Probabilistic Bisimulation: Naturally on Distributions
In contrast to the usual understanding of probabilistic systems as stochastic
processes, recently these systems have also been regarded as transformers of
probabilities. In this paper, we give a natural definition of strong
bisimulation for probabilistic systems corresponding to this view that treats
probability distributions as first-class citizens. Our definition applies in
the same way to discrete systems as well as to systems with uncountable state
and action spaces. Several examples demonstrate that our definition refines the
understanding of behavioural equivalences of probabilistic systems. In
particular, it solves a long-standing open problem concerning the
representation of memoryless continuous time by memory-full continuous time.
Finally, we give algorithms for computing this bisimulation not only for finite
but also for classes of uncountably infinite systems
Lattice investigation of the general Two Higgs Doublet Model with gauge fields
We study the most general Two Higgs Doublet Model with gauge fields
on the lattice. The phase space is probed through the computation of
gauge-invariant global observables serving as proxies for order parameters. In
each phase, the spectrum of the theory is analysed for different combinations
of bare couplings and different symmetry breaking patterns. The scale setting
and determination of the running gauge coupling are performed through the
Wilson flow computation of the action density
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