340 research outputs found
A transformation method to study the solvability of fully coupled FBSDEs
We present a new method for checking global solvability of fully coupled forward-backward stochastic differential equations (FBSDEs), where all function parameters are Lipschitz continuous, the terminal condition is monotone and the diffusion coefficient of the forward part depends monotonically on z, the control process component of the backward part. We show that one can reduce, via a linear transformation, the FBSDE to an auxiliary FBSDE for which the Lipschitz constant of the forward diffusion coefficient w.r.t. z is smaller than the inverse of the Lipschitz constant of the terminal condition w.r.t. the forward component x. The latter condition allows to verify existence of a global solution by analyzing the space derivative of the decoupling field. We illustrate with several examples how the transformation method can be used for proving global solvability of FBSDEs
linking goal-directed and model-based behavior
In experimental psychology different experiments have been developed to assess
goal–directed as compared to habitual control over instrumental decisions.
Similar to animal studies selective devaluation procedures have been used.
More recently sequential decision-making tasks have been designed to assess
the degree of goal-directed vs. habitual choice behavior in terms of an
influential computational theory of model-based compared to model-free
behavioral control. As recently suggested, different measurements are thought
to reflect the same construct. Yet, there has been no attempt to directly
assess the construct validity of these different measurements. In the present
study, we used a devaluation paradigm and a sequential decision-making task to
address this question of construct validity in a sample of 18 healthy male
human participants. Correlational analysis revealed a positive association
between model-based choices during sequential decisions and goal-directed
behavior after devaluation suggesting a single framework underlying both
operationalizations and speaking in favor of construct validity of both
measurement approaches. Up to now, this has been merely assumed but never been
directly tested in humans
Un modèle de canal multi-trajets appliqué à la simulation rapide du lien UMTS
- Cet article propose une méthode de simulation simplifiée du lien radio. Son originalité consiste en la modélisation simplifiée du récepteur et du canal, qui reste très fidèle. Cette méthode de simulation rapide est très précise et le gain en complexité est important. L'exemple des services 12.2 et 64 kbps de l'UMTS FDD à 3 et 120 km/h pour les canaux du 3GPP montre très peu de différence entre les performances des simulateurs traditionnel et simplifié
The Iberian Peninsula in the Imperial and Post-Imperial Context
This paper investigates the way in which technical and normative knowledge
relating to infrastructures, mobility and water management, which the Romans
began developing in the republican period, was functionalized for the purpose
of expanding the empire in the Iberian Peninsula, starting with the
establishment of Roman provincial rule and continuing into the Islamic epoch.
It also examines how that knowledge was entrenched in the individual Iberian
provinces, and adapted to reflect specific local features. In addition to
shedding light on how imperial concepts manifested themselves in the
appropriation of space in specific contexts, the example of the Iberian
Peninsula elucidates both how the knowledge in question was adapted to meet
‘regional-political’ objectives once the imperial frame of reference fell away
and how it was ultimately restructured, modified and legitimized to reflect
overriding religious considerations. The paper also provides examples
indicating the degree to which antique concepts lent themselves to
transformation while simultaneously representing both a potential and a
challenge for any subsequent rulers
Discovery of an old nova remnant in the Galactic globular cluster M 22
A nova is a cataclysmic event on the surface of a white dwarf in a binary
system that increases the overall brightness by several orders of magnitude.
Although binary systems with a white dwarf are expected to be overabundant in
globular clusters (GCs) compared to the Galaxy, only two novae from Galactic
globular clusters have been observed. We present the discovery of an emission
nebula in the Galactic globular cluster M 22 (NGC 6656) in observations made
with the integral-field spectrograph MUSE. We extract the spectrum of the
nebula and use the radial velocity determined from the emission lines to
confirm that the nebula is part of NGC 6656. Emission-line ratios are used to
determine the electron temperature and density. It is estimated to have a mass
of 1 to solar masses. This mass and the emission-line
ratios indicate that the nebula is a nova remnant. Its position coincides with
the reported location of a 'guest star', an ancient Chinese term for
transients, observed in May 48 BCE. With this discovery, this nova may be one
of the oldest confirmed extrasolar events recorded in human history.Comment: 7 pages, 3 figures; accepted for publication in Astronomy &
Astrophysic
Effect of Speech Rate on Neural Tracking of Speech
Speech comprehension requires effort in demanding listening situations. Selective attention may be required for focusing on a specific talker in a multi-talker environment, may enhance effort by requiring additional cognitive resources, and is known to enhance the neural representation of the attended talker in the listener’s neural response. The aim of the study was to investigate the relation of listening effort, as quantified by subjective effort ratings and pupil dilation, and neural speech tracking during sentence recognition. Task demands were varied using sentences with varying levels of linguistic complexity and using two different speech rates in a picture-matching paradigm with 20 normal-hearing listeners. The participants’ task was to match the acoustically presented sentence with a picture presented before the acoustic stimulus. Afterwards they rated their perceived effort on a categorical effort scale. During each trial, pupil dilation (as an indicator of listening effort) and electroencephalogram (as an indicator of neural speech tracking) were recorded. Neither measure was significantly affected by linguistic complexity. However, speech rate showed a strong influence on subjectively rated effort, pupil dilation, and neural tracking. The neural tracking analysis revealed a shorter latency for faster sentences, which may reflect a neural adaptation to the rate of the input. No relation was found between neural tracking and listening effort, even though both measures were clearly influenced by speech rate. This is probably due to factors that influence both measures differently. Consequently, the amount of listening effort is not clearly represented in the neural tracking
Draft Genome Sequences of Three Porcine Streptococcus suis Isolates Which Differ in Their Susceptibility to Penicillin
The draft genome sequences of three Streptococcus suis isolates, IMT40343, IMT40201, and IMT40738, are presented here. These isolates were obtained from bronchoalveolar lavage fluid of healthy and diseased weaners from different German piglet-producing farms and differed in their susceptibility to penicillin
Do Mutual Fund Ratings Provide Valuable Information for Retail Investors? Empirical Evidence on Ratings Non-Persistence and the Risk of Mutual Fund Closure
Retail investors use information provided by mutual fund rating agencies to make investment decisions. Using hand-collected data on Morningstar’s mutual fund ratings we examine the rating migration and closure risk of mutual funds from 2005 to 2012. We differentiate between buy-and-hold investment strategies and dynamic investment strategies. To assess the information content of mutual fund ratings for buy-and-hold investment strategies, we determine the rating migration based on the first and the last mutual fund rating during two-, four-, six-, and eight-year horizons. With respect to dynamic investment strategies, we calculate the number of rating changes per fund during these time horizons on a monthly basis. We find that mutual fund rating persistence is low or even inexistent in particular during longer time periods. Only for lower-rated funds the rating appears to indicate higher risk of fund closure. In addition, mutual funds face a large number of up to 38 monthly rating changes in the eight-year window. Overall, due to the extensive rating migration and the high number of monthly rating changes, we conclude that retail investors barely benefit from using mutual fund ratings
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