24,397 research outputs found
Discovering Motion Flow by Temporal-Informational Correlations in Sensors
A method is presented for adapting the sensors
of a robot to its current environment and
to learn motion flow detection by observing
the informational relations between sensors
and actuators. Examples are shown where
the robot learns to detect motion flow from
sensor data generated by its own movement
Wigner flow reveals topological order in quantum phase space dynamics
The behaviour of classical mechanical systems is characterised by their phase
portraits, the collections of their trajectories. Heisenberg's uncertainty
principle precludes the existence of sharply defined trajectories, which is why
traditionally only the time evolution of wave functions is studied in quantum
dynamics. These studies are quite insensitive to the underlying structure of
quantum phase space dynamics. We identify the flow that is the quantum analog
of classical particle flow along phase portrait lines. It reveals hidden
features of quantum dynamics and extra complexity. Being constrained by
conserved flow winding numbers, it also reveals fundamental topological order
in quantum dynamics that has so far gone unnoticed.Comment: 6 pages, 6 figure
Development of software to plan conversion to organic production (OrgPlan)
This report was presented at the UK Organic Research 2002 Conference. OrgPlan is a computer programme aimed at farmers and advisors assisting with the planning of an organic conversion. The programme is divided into technical modules, supported by a standard enterprise database, a report builder and an advisory section. Through the farm profile builder, rotation, cropping and livestock planner, conversion scenarios over several years can be developed and are evaluated for technical and financial feasibility by calculating farm gate budgets for key resources (forage energy and key nutrients) and financial reports (cash flow budget and profit and loss account). The poster illustrates the basic functioning of the software as well as the underlying rationale for the scenario evaluation
A Hot Uranus Orbiting the Super Metal-rich Star HD77338 and the Metallicity - Mass Connection
We announce the discovery of a low-mass planet orbiting the super metal-rich
K0V star HD77338 as part of our on-going Calan-Hertfordshire Extrasolar Planet
Search. The best fit planet solution has an orbital period of 5.7361\pm0.0015
days and with a radial velocity semi-amplitude of only 5.96\pm1.74 m/s, we find
a minimum mass of 15.9+4.7-5.3 Me. The best fit eccentricity from this solution
is 0.09+0.25-0.09, and we find agreement for this data set using a Bayesian
analysis and a periodogram analysis. We measure a metallicity for the star of
+0.35\pm0.06 dex, whereas another recent work (Trevisan et al. 2011) finds
+0.47\pm0.05 dex. Thus HD77338b is one of the most metal-rich planet host stars
known and the most metal-rich star hosting a sub-Neptune mass planet. We
searched for a transit signature of HD77338b but none was detected. We also
highlight an emerging trend where metallicity and mass seem to correlate at
very low masses, a discovery that would be in agreement with the core accretion
model of planet formation. The trend appears to show that for Neptune-mass
planets and below, higher masses are preferred when the host star is more
metal-rich. Also a lower boundary is apparent in the super metal-rich regime
where there are no very low-mass planets yet discovered in comparison to the
sub-solar metallicity regime. A Monte Carlo analysis shows that this, low-mass
planet desert, is statistically significant with the current sample of 36
planets at around the 4.5\sigma\ level. In addition, results from Kepler
strengthen the claim for this paucity of the lowest-mass planets in super
metal-rich systems. Finally, this discovery adds to the growing population of
low-mass planets around low-mass and metal-rich stars and shows that very
low-mass planets can now be discovered with a relatively small number of data
points using stable instrumentation.Comment: 25 pages, 15 figures, 5 tables, accepted for publication in Ap
Astrophysical Reaction Rates From Statistical Model Calculations
Theoretical reaction rates in the temperature range 0.01*10^9<=T[K]<=10.*10^9
are calculated in the statistical model (Hauser-Feshbach formalism) for targets
with 10<=Z<=83 (Ne to Bi) and for a mass range reaching the neutron and proton
driplines. Reactions considered are (n,gamma), (n,p), (n,alpha), (p,gamma),
(p,alpha),(alpha,gamma), and their inverse reactions. Reaction rates as a
function of temperature for thermally populated targets are given by analytic
seven parameter fits. To facilitate comparison with experimental rates, the
stellar enhancement factors are also tabulated. Two complete sets of rates have
been calculated, one of which includes a phenomenological treatment of shell
quenching for neutron-rich nuclei. These extensive datasets are provided
on-line as electronic files, while a selected subset from one calculation is
given as printed tables. A summary of the theoretical inputs and advice on the
use of the provided tabulations is included.Comment: 22 pages of text and 1 table; accepted by Atomic Data Nuclear Data
Tables; a preprint is also available from
http://quasar.physik.unibas.ch/~tommy/adndt.htm
High Performance Associative Memories and Structured Weight Dilution
Copyright SpringerThe consequences of two techniques for symmetrically diluting the weights of the standard Hopfield architecture associative memory model, trained using a non-Hebbian learning rule, are examined. This paper reports experimental investigations into the effect of dilution on factors such as: pattern stability and attractor performance. It is concluded that these networks maintain a reasonable level of performance at fairly high dilution rates
Logic in Action: Wittgenstein's Logical Pragmatism and the Impotence of Scepticism
‘The definitive version is available at www3.interscience.wiley.com '. Copyright Blackwell Publishing. DOI: 10.1111/1467-9205.00291Peer reviewe
Molecular self-organisation in a developmental model for the evolution of large-scale artificial neural networks
We argue that molecular self-organisation during embryonic development allows evolution to perform highly nonlinear combinatorial optimisation. A structured approach to architectural optimisation of large-scale Artificial Neural Networks using this principle is presented. We also present simulation results demonstrating the evolution of an edge detecting retina using the proposed methodology
Middle Pleistocene Till Lithostratigraphy in South Bedfordshire and the Hitchin Gap
A revised lithostratigraphy and glacial history of north Hertfordshire and south
Bedfordshire is based upon detailed textural data in the clay to fine gravel fraction, carbonate content, small clast lithological data and macrofabrics, derived from laboratory and field analyses of tills from 30 sites. These include four deep boreholes sunk within the Hitchin Gap. A range of statistical procedures was used, including multivariate analysis of the petrographic
properties, enabling the identification of tills from two separate incursions into
the Gap. A further till-type was identified in south Bedfordshire indicating an ice
advance from the northwest/NNW extending at least as far east as Milton Bryan. Statistical comparison with tills in the neighbouring Vale of St. Albans suggested the presence of the Ware Member till within the Gap.
Two hypotheses are suggested to explain variations in lithological content of tills
north of the Chalk scarp. The first envisages ice entering the study area along
the different trajectories suggested by Fish and Whiteman (2001). During the
early part of the glaciation, ice reaching the west of the study area would
approach from the north, crossing a shorter distance over Chalk bedrock and
collecting less chalk and flint than ice moving into the eastern part of the study
area. The second hypothesis invokes an incursion of ice from a northwest -
NNW direction into the west of the study area, depositing a chalk-free till. This
is subsequently assimilated by ice from the northeast, resulting in the final
deposition of a homogeneous mixture of debris from the two advances, with a
lower chalk content than tills found to the east. The outcome of either of these
scenarios is a till with a low acid-soluble content and low flint/quartz ratio in the
west of the study area, as found during this work.
Within the Hitchin Gap, a lobe of ice, probably an early part of the northeasterly
advance, deposited a lower till. This is considered to be earlier than the Ware
Member till and has more variable lithological characteristics and a finer matrix that the higher tills. The latter are mainly melt-out, flow or slumped tills with
occasional instances of lodgement and deformation. They represent in situ
wasting of dead ice within the Gap. Surface tills in the Gap form a continuum with tills to the north and comprise mainly deformation tills, deposited by the final northeasterly re-advance of ice responsible for widespread coverage of the region, with the exception of the Chiltern Hills southwest of Hitchin. No evidence is found of more than one lithostratigraphic unit of till outside the
Hitchin Gap
Developing high-fidelity health care simulation scenarios : a guide for educators and professionals
“The final, definitive version of this article has been published in the Journal, Simulation & Gaming, 42 (1), 2011, copyright SAGE Publications Ltd on SAGE Journals Online: http://online.sagepub.com/ "The development of appropriate scenarios is critical in high-fidelity simulation training. They need to be developed to address specific learning objectives, while not preventing other learning points from emerging. Buying a patient simulator, finding a volunteertoact as the patient, or even obtaining ready-made scenarios from another simulation center are rarely insurmountable challenges. The issue often lies in how to use or adapt these for your own purpose: with your team, facilities, and resources but primarily for your learners. Published information is limited in the area of scenario preparation for health care education and continuing medical education or continuing professional development. This article is a guide for clinical tutors, standardized patient trainers, and patient simulator operators on how to script scenarios and proposes a new detailed and reusable template for writing scenarios. It contains practical sections such as how to decide on the learning objectives to be addressed, how to script and organize your scenarios, and how to pitch the suitable level of details to make the scenarios appropriately realistic.Peer reviewe
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