2,243 research outputs found
Information theoretic approach to interactive learning
The principles of statistical mechanics and information theory play an
important role in learning and have inspired both theory and the design of
numerous machine learning algorithms. The new aspect in this paper is a focus
on integrating feedback from the learner. A quantitative approach to
interactive learning and adaptive behavior is proposed, integrating model- and
decision-making into one theoretical framework. This paper follows simple
principles by requiring that the observer's world model and action policy
should result in maximal predictive power at minimal complexity. Classes of
optimal action policies and of optimal models are derived from an objective
function that reflects this trade-off between prediction and complexity. The
resulting optimal models then summarize, at different levels of abstraction,
the process's causal organization in the presence of the learner's actions. A
fundamental consequence of the proposed principle is that the learner's optimal
action policies balance exploration and control as an emerging property.
Interestingly, the explorative component is present in the absence of policy
randomness, i.e. in the optimal deterministic behavior. This is a direct result
of requiring maximal predictive power in the presence of feedback.Comment: 6 page
Improving the performance of a traffic system by fair rerouting of travelers
Some traffic management measures route drivers towards socially-desired paths in order to achieve the system optimum: the traffic state with minimum total travel time. In previous attempts, the behavioral response to route advice is often not accounted for since some drivers are advised to take significantly longer paths for the system’s benefit. Hence, these drivers may not comply with such advice and the optimal state will not be achieved. In this paper, we propose a social routing strategy to approach the optimal state while accounting for fairness in the resulting state. This routing strategy asks travelers to take a limited detour in order to improve efficiency. We show that the best possible paths (in terms of efficiency) to be proposed by a service adopting this strategy can be found by solving a bilevel optimization problem with a non-unique lower-level solution. We use techniques from parametric analysis to show that the directional derivative of the lower-level link flows however exists. This derivative is the optimal solution of a quadratic optimization problem with a suitable route flow solution as parameter. We use the derivative in a descent algorithm to solve the bilevel problem. Numerical experiments in a realistic environment show that the routing strategy only asks a small fraction of the drivers to take a limited detour and thereby substantially improves the performance of the traffic system
Age and Waist Circumference Modify Discordance of Body Fat Measurements in Adults with Obesity
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A burst from the direction of UZ Fornacis with XMM-Newton
The XMM-Newton pointing towards the magnetic cataclysmic variable UZ For
finds the source to be a factor > 10^3 fainter than previous EXOSAT and ROSAT
observations. The source was not detected for the majority of a 22 ksec
exposure with the EPIC cameras, suggesting that the accretion rate either
decreased, or stopped altogether. However a 1.1 ksec burst was detected from UZ
For during the observation. Spectral fits favour optically thin, kT = 4.4 keV
thermal emission. Detection of the burst by the on-board Optical Monitor
indicates that this was most probably an accretion event. The 0.1-10 keV
luminosity of 2.1 x 10^30 erg/s is typical for accretion shock emission from
high state polars and would result from the potential energy release of ~ 10^16
g of gas. There is no significant soft excess due to reprocessing in the white
dwarf atmosphere.Comment: 7 pages, 2 postscript figures, ApJL, in pres
Deposition And Drying Dynamics Of Liquid Crystal Droplets
Drop drying and deposition phenomena reveal a rich interplay of fundamental science and engineering, give rise to fascinating everyday effects (coffee rings), and influence technologies ranging from printing to genotyping. Here we investigate evaporation dynamics, morphology, and deposition patterns of drying lyotropic chromonic liquid crystal droplets. These drops differ from typical evaporating colloidal drops primarily due to their concentration-dependent isotropic, nematic, and columnar phases. Phase separation occurs during evaporation, and in the process creates surface tension gradients and significant density and viscosity variation within the droplet. As a result, the drying multiphase drops exhibit different convective currents, drop morphologies, and deposition patterns (coffee-rings)
Comparison of Measured and Predicted Resting Energy Expenditure in Obese Pre-bariatric Surgery Patients
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Hercules X-1: Empirical Models of UV Emission Lines
The UV emission lines of Hercules X-1, resolved with the HST GHRS and STIS,
can be divided into broad (FWHM 750 km/s) and narrow (FWHM 150 km/s)
components. The broad lines can be unambiguously identified with emission from
an accretion disk which rotates prograde with the orbit. The narrow lines,
previously identified with the X-ray illuminated atmosphere of the companion
star, are blueshifted at both phi=0.2 and phi=0.8 and the line flux at phi=0.2
is 0.2 of the flux at phi=0.8. Line ratio diagnostics show that the density of
the narrow line region is log n=13.4+/-0.2 and the temperature is
T=1.0+/-0.2x10^5 K. The symmetry of the eclipse ingress suggests that the line
emission on the surface of the disk is left-right symmetric relative to the
orbit. Model fits to the O V, Si IV, and He II line profiles agree with this
result, but fits to the N V lines suggest that the receding side of the disk is
brighter. We note that there are narrow absorption components in the N V lines
with blueshifts of 500 km/s.Comment: To be published in the Astrophysical Journa
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