6,532 research outputs found
Flexibly Instructable Agents
This paper presents an approach to learning from situated, interactive
tutorial instruction within an ongoing agent. Tutorial instruction is a
flexible (and thus powerful) paradigm for teaching tasks because it allows an
instructor to communicate whatever types of knowledge an agent might need in
whatever situations might arise. To support this flexibility, however, the
agent must be able to learn multiple kinds of knowledge from a broad range of
instructional interactions. Our approach, called situated explanation, achieves
such learning through a combination of analytic and inductive techniques. It
combines a form of explanation-based learning that is situated for each
instruction with a full suite of contextually guided responses to incomplete
explanations. The approach is implemented in an agent called Instructo-Soar
that learns hierarchies of new tasks and other domain knowledge from
interactive natural language instructions. Instructo-Soar meets three key
requirements of flexible instructability that distinguish it from previous
systems: (1) it can take known or unknown commands at any instruction point;
(2) it can handle instructions that apply to either its current situation or to
a hypothetical situation specified in language (as in, for instance,
conditional instructions); and (3) it can learn, from instructions, each class
of knowledge it uses to perform tasks.Comment: See http://www.jair.org/ for any accompanying file
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PERSIANN-MSA: A precipitation estimation method from satellite-based multispectral analysis
Visible and infrared data obtained from instruments onboard geostationary satellites have been extensively used for monitoring clouds and their evolution. The Advanced Baseline Imager (ABI) that will be launched onboard the Geostationary Operational Environmental Satellite-R (GOES-R) series in the near future will offer a larger range of spectral bands; hence, it will provide observations of cloud and rain systems at even finer spatial, temporal, and spectral resolutions than are possible with the current GOES. In this paper, a new method called Precipitation Estimation from Remotely Sensed information using Artificial Neural Networks-Multispectral Analysis (PERSIANN-MSA) is proposed to evaluate the effect of using multispectral imagery on precipitation estimation. The proposed approach uses a self-organizing feature map (SOFM) to classify multidimensional input information, extracted from each grid box and corresponding textural features of multispectral bands. In addition, principal component analysis (PCA) is used to reduce the dimensionality to a few independent input features while preserving most of the variations of all input information. The above method is applied to estimate rainfall using multiple channels of the Spinning Enhanced Visible and Infrared Imager (SEVIRI) onboard the Meteosat Second Generation (MSG) satellite. In comparison to the use of a single thermal infrared channel, the analysis shows that using multispectral data has the potential to improve rain detection and estimation skills with an average of more than 50% gain in equitable threat score for rain/no-rain detection, and more than 20% gain in correlation coefficient associated with rain-rate estimation. © 2009 American Meteorological Society
Block synchronization for quantum information
Locating the boundaries of consecutive blocks of quantum information is a
fundamental building block for advanced quantum computation and quantum
communication systems. We develop a coding theoretic method for properly
locating boundaries of quantum information without relying on external
synchronization when block synchronization is lost. The method also protects
qubits from decoherence in a manner similar to conventional quantum
error-correcting codes, seamlessly achieving synchronization recovery and error
correction. A family of quantum codes that are simultaneously synchronizable
and error-correcting is given through this approach.Comment: 7 pages, no figures, final accepted version for publication in
Physical Review
When a Nudge Isn’t Enough: Defaults and Saving Among Low-Income Tax Filers
Recent evidence suggests that the default options implicit in economic choices (e.g., 401(k) savings by white-collar workers) have extraordinarily large effects on decision-making. This study presents a field experiment that evaluates the effect of defaults on savings among a highly policy-relevant population: low-income tax filers. In the control condition, tax filers could choose (i.e., opt in) to receive some of their federal tax refund in the form of U.S. Savings Bonds. In the treatment condition, a fraction of the tax refund was automatically directed to U.S. Savings Bonds unless tax filers actively chose another allocation. We find that the opt-out default had no impact on savings behavior. Furthermore, our treatment estimate is sufficiently precise to reject effects as small as one-fifth of the participation effects found in the 401(k) literature. Ancillary evidence suggests that this "nudge" was ineffective in part because the low-income tax filers in our study had targeted plans to spend their refunds. These results suggest that choice architecture based on defaults may be less effective in certain policy-relevant settings, particularly where intentions are strong.
Constraints on Parity-Even Time Reversal Violation in the Nucleon-Nucleon System and Its Connection to Charge Symmetry Breaking
Parity-even time reversal violation (TRV) in the nucleon-nucleon interaction
is reconsidered. The TRV -exchange interaction on which recent analyses
of measurements are based is necessarily also charge-symmetry breaking (CSB).
Limits on its strength relative to regular -exchange are
extracted from recent CSB experiments in neutron-proton scattering. The result
(95% CL) is considerably lower than limits
inferred from direct TRV tests in nuclear processes. Properties of
-exchange and limit imposed by the neutron EDM are briefly discussed.Comment: RevTex, 8 pages. Factor ten error in cited neutron EDM corrected,
discussion and two references adde
"Where the mask ends and the face begins is not certain": Mediating ethnicity and cheating geography in Jonny Steinberg's Little Liberia
Mixing historical commentary, reportage, biography and personal stories, South
African writer Jonny Steinberg takes up the tale of a fractured African nation and its
diaspora in Little Liberia: An African Odyssey in New York City (2011). The "little
Liberia" founded in New York's urban jungle may have represented, for many of its
inhabitants, a way to "cheat geography" by recreating a home away from home, but
Little Liberia shows the reader it has not allowed them to cheat history. The book
deals with the lives of two inhabitants of Park Hill Avenue on Staten Island, where
nearly everyone is Liberian. Their conflict threatens to implode the community, igniting
suspicions and accusations that had been bottled up since their exile. The article
focuses on the interface of mediated ethnicity and citizenship related to the struggle
for power in the diasporic Liberian community on Staten Island. Attention is also paid
to feelings of identity of Little Liberia's author.DHE
An exploration of personal benefits reported by students of a health and wellness coach training programme
This study explores the ‘personal benefits’ of training reported by graduates of a health and wellness coach training programme. In particular, we investigated reported benefits, areas of life affected by the training, and whether changes occurred in health and wellness or more broadly. Using a semi-structured interview design, we incorporated an atheoretical qualitative approach to data collection and analysis. Thematic analysis was used at a semantic level to identify the major themes. The findings indicate a blend of personal and professional benefits for the graduate. As a result of participation in the programme, graduates gained greater self-knowledge, and better connection with others. They also improved their professional optimism and noted positive changes in personal health and wellbeing. Further research is needed to see if trainees from other health and wellness coach training programmes report similar personal benefits, and to identify key training elements instrumental to generating these benefits
A Microscopic T-Violating Optical Potential: Implications for Neutron-Transmission Experiments
We derive a T-violating P-conserving optical potential for neutron-nucleus
scattering, starting from a uniquely determined two-body -exchange
interaction with the same symmetry. We then obtain limits on the T-violating
-nucleon coupling from neutron-transmission
experiments in Ho. The limits may soon compete with those from
measurements of atomic electric-dipole moments.Comment: 8 pages, 2 uuencoded figures in separate files (replaces version sent
earlier in the day with figures attached), in RevTeX 3, submitted to PR
A unified approach to combinatorial key predistribution schemes for sensor networks
There have been numerous recent proposals for key predistribution schemes for wireless sensor networks based on various types of combinatorial structures such as designs and codes. Many of these schemes have very similar properties and are analysed in a similar manner. We seek to provide a unified framework to study these kinds of schemes. To do so, we define a new, general class of designs, termed “partially balanced t-designs”, that is sufficiently general that it encompasses almost all of the designs that have been proposed for combinatorial key predistribution schemes. However, this new class of designs still has sufficient structure that we are able to derive general formulas for the metrics of the resulting key predistribution schemes. These metrics can be evaluated for a particular scheme simply by substituting appropriate parameters of the underlying combinatorial structure into our general formulas. We also compare various classes of schemes based on different designs, and point out that some existing proposed schemes are in fact identical, even though their descriptions may seem different. We believe that our general framework should facilitate the analysis of proposals for combinatorial key predistribution schemes and their comparison with existing schemes, and also allow researchers to easily evaluate which scheme or schemes present the best combination of performance metrics for a given application scenario
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