1,293 research outputs found
Factor Varieties
The universal algebraic literature is rife with generalisations of discriminator varieties, whereby several investigators have tried to preserve in more general settings as much as possible of their structure theory. Here, we modify the definition of discriminator algebra by having the switching function project onto its third coordinate in case the ordered pair of its first two coordinates belongs
to a designated relation (not necessarily the diagonal relation). We call these algebras factor algebras and the varieties they generate factor varieties. Among other things, we provide an equational description of these varieties and match equational conditions involving the factor term with properties of the associated factor relation. Factor varieties include, apart from discriminator varieties, several varieties of algebras from quantum and fuzzy logics
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An integrated building demolition and waste planning model for the Fernald Site
The Fernald DOE site will begin full-scale remediation of buildings under the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) during the 1995 fiscal year pursuant to a signed Record of Decision. This effort is currently estimated to cost $350 million and span a minimum duration of 8 years, if funding is not a constraint. The identification of the most viable sequence and schedule for the effort involved the development of an integrated planning model and the commissioning of a sitewide planning team. The resulting work product represents the best combination of assumptions and calculations possible at this time and provides information necessary for compliance with the CERCLA Remedial Design documentation requirements for the over 230 component structures governed by the decision. Sequence and integrated schedule development for the decontamination and dismantlement (D&D) of Fernald structures has involved evaluation of current and future utilization of structures, availability of waste storage and staging space, the needs and impacts of other on-going Fernald projects, Resource Conservation and Recovery Act (RCRA) waste management and remediation projects, the layout of site utilities, site hydrology, and the potential sizing, location, and construction rates for an on-property disposal cell
Ontologies for Intelligent e-Theraoy: Application to Obesity
[EN] In this paper we propose a new approach for mental e-health
treatments named intelligent e-therapy (e-it) with capabilities for ambient intelligence
and ubiquitous computing. The proposed e-it system supposes an evolution
of cybertherapy and telepsychology tools used up to now. The e-it system
is based in a knowledge base that includes all the knowledge related to the disorder
and its treatment. We introduce the use of ontologies as the best option for
the design of this knowledge base. We also present a fist e-it system for obesity
treatment called etiobeZaragozĂĄ Ălvarez, I.; Guixeres Provinciale, J.; Alcañiz Raya, ML. (2009). Ontologies for Intelligent e-Theraoy: Application to Obesity. Lecture Notes in Computer Science. 5518:894-901. doi:10.1007/978-3-642-02481-8_136S8949015518Baños, R.M., Botella, C., Perpiñå, C., Alcañiz, M., Lozano, J.A., Osma, J., Gallardo, M.: Virtual reality treatment of flying phobia. IEEE Transactions on Information Technology in Biomedicine 6(3), 206â212 (2002)Botella, C., Baños, R.M., Perpiña, C., et al.: Virtual reality treatment of claustrophobia: a case report. Behaviour Research & Therapy 36, 239â246 (1998)Hu, B., Dasmahapatra, S., Dupplaw, D., Lewis, P., Shadbolt, N.: Reflections on a medical ontology. International Journal of Human- Computer Studies 65(2007), 569â582 (2007)Rubin, D.L., Shah, N.H., Noy, N.F.: Biomedical ontologies: a functional perspective. Briefings in bioinformatics 9(1), 75â90 (2007)Stevens, R., Egaña Aranguren, M., Wolstencroft, K., Sattler, U., Drummond, N., Horridge, M., Rector, A.: Using OWL to model biological knowledge. International Journal of Human-Computer Studies 65(2007), 583â594 (2007)Park, S., Lee, J.K.: Rule identification using ontology while acquiring rules from Web pages. International Journal of Human-Computer Studies 65(2007), 644â658 (2007)Clark, K.L., McCabe, F.G.: Ontology schema for an agent belief store. International Journal of Human-Computer Studies 65(2007), 625â643 (2007)Gruber, T.R.: A Translation Approach to Portable Ontology Specifications. Knowledge Acquisition 5(2), 199â220 (1993)Franco, C., Bengtsson, B., Johannsson, G.: The GH/IGF-1 Axis in Obesity: Physiological and Pathological aspects. Metabolic syndrome and Related Disorders 4, 51â56 (2006
Approximate solution of the Duffin-Kemmer-Petiau equation for a vector Yukawa potential with arbitrary total angular momenta
The usual approximation scheme is used to study the solution of the
Duffin-Kemmer-Petiau (DKP) equation for a vector Yukawa potential in the
framework of the parametric Nikiforov-Uvarov (NU) method. The approximate
energy eigenvalue equation and the corresponding wave function spinor
components are calculated for arbitrary total angular momentum in closed form.
Further, the approximate energy equation and wave function spinor components
are also given for case. A set of parameter values is used to obtain the
numerical values for the energy states with various values of quantum levelsComment: 17 pages; Communications in Theoretical Physics (2012). arXiv admin
note: substantial text overlap with arXiv:1205.0938, and with
arXiv:quant-ph/0410159 by other author
Optical, X-ray, and Îł-ray observations of the candidate transitional millisecond pulsar 4FGL J0427.8-6704
We present an optical, X-ray, and Îł-ray study of 1SXPS J042749.2-670434, an eclipsing X-ray binary that has an associated Îł-ray counterpart, 4FGL J0427.8-6704. This association has led to the source being classified as a transitional millisecond pulsar (tMSP) in an accreting state. We analyse 10.5 yr of Fermi LAT data and detect a Îł-ray eclipse at the same phase as optical and X-ray eclipses at the >5âÏ level, a significant improvement on the 2.8âÏ level of the previous detection. The confirmation of this eclipse solidifies the association between the X-ray source and the Îł-ray source, strengthening the tMSP classification. However, analysis of several optical data sets and an X-ray observation do not reveal a change in the sourceâs median brightness over long time-scales or a bi-modality on short time-scales. Instead, the light curve is dominated by flickering, which has a correlation time of 2.6 min alongside a potential quasi-periodic oscillation at âŒ21 min. The mass of the primary and secondary stars is constrained to be M1=1.43+0.33â0.19 Mâ and M2=0.3+0.17â0.12 Mâ through modelling of the optical light curve. While this is still consistent with a white dwarf primary, we favour the tMSP in a low accretion state classification due to the significance of the Îł-ray eclipse detection
Long-Ranged Correlations in Sheared Fluids
The presence of long-ranged correlations in a fluid undergoing uniform shear
flow is investigated. An exact relation between the density autocorrelation
function and the density-mometum correlation function implies that the former
must decay more rapidly than , in contrast to predictions of simple mode
coupling theory. Analytic and numerical evaluation of a non-perturbative
mode-coupling model confirms a crossover from behavior at ''small''
to a stronger asymptotic power-law decay. The characteristic length scale is
where is the sound damping
constant and is the shear rate.Comment: 15 pages, 2 figures. Submitted to PR
Active Amplification of the Terrestrial Albedo to Mitigate Climate Change: An Exploratory Study
This study explores the potential to enhance the reflectance of solar
insolation by the human settlement and grassland components of the Earth's
terrestrial surface as a climate change mitigation measure. Preliminary
estimates derived using a static radiative transfer model indicate that such
efforts could amplify the planetary albedo enough to offset the current global
annual average level of radiative forcing caused by anthropogenic greenhouse
gases by as much as 30 percent or 0.76 W/m2. Terrestrial albedo amplification
may thus extend, by about 25 years, the time available to advance the
development and use of low-emission energy conversion technologies which
ultimately remain essential to mitigate long-term climate change. However,
additional study is needed to confirm the estimates reported here and to assess
the economic and environmental impacts of active land-surface albedo
amplification as a climate change mitigation measure.Comment: 21 pages, 3 figures. In press with Mitigation and Adaptation
Strategies for Global Change, Springer, N
A rapid optical and X-ray timing study of the neutron star X-ray binary Swift J1858.6â0814
We present a rapid timing analysis of optical (HiPERCAM and ULTRACAM) and X-ray (NICER) observations of the X-ray transient SwiftâJ1858.6â0814 during 2018 and 2019. The optical light curves show relatively slow, large amplitude (âŒ1âmag in gs) âblueâ flares (i.e. stronger at shorter wavelengths) on time-scales of âŒminutes as well as fast, small amplitude (âŒ0.1âmag in gs) âredâ flares (i.e. stronger at longer wavelengths) on time-scales of âŒseconds. The âblueâ and âredâ flares are consistent with X-ray reprocessing and optically thin synchrotron emission, respectively, similar to what is observed in other X-ray binaries. The simultaneous optical versus soft- and hard-band X-ray light curves show time- and energy-dependent correlations. The 2019 March 4 and parts of the June data show a nearly symmetric positive cross-correlations (CCFs) at positive lags consistent with simple X-ray disc reprocessing. The soft- and hard-band CCFs are similar and can be reproduced if disc reprocessing dominates in the optical and one component (disc or synchrotron Comptonization) dominates both the soft and hard X-rays. A part of the 2019 June data shows a very different CCFs. The observed positive correlation at negative lag in the soft band can be reproduced if the optical synchrotron emission is correlated with the hot flow X-ray emission. The observed timing properties are in qualitative agreement with the hybrid inner hot accretion flow model, where the relative role of the different X-ray and optical components that vary during the course of the outburst, as well as on shorter time-scales, govern the shape of the optical/X-ray CCFs
Measuring the mass of the black widow PSR J1555-2908
Accurate measurements of the masses of neutron stars are necessary to test
binary evolution models, and to constrain the neutron star equation of state.
In pulsar binaries with no measurable post-Keplerian parameters, this requires
an accurate estimate of the binary system's inclination and the radial velocity
of the companion star by other means than pulsar timing. In this paper, we
present the results of a new method for measuring this radial velocity using
the binary synthesis code Icarus. This method relies on constructing a model
spectrum of a tidally distorted, irradiated star as viewed for a given binary
configuration. This method is applied to optical spectra of the newly
discovered black widow PSR J1555-2908. By modelling the optical spectroscopy
alongside optical photometry, we find that the radial velocity of the companion
star is km s (errors quoted at 95\% confidence interval), as
well as a binary inclination of . Combined with -ray
pulsation timing information, this gives a neutron star mass of
1.67 M and a companion mass of
0.060 M, placing PSR J1555-2908 at the observed
upper limit of what is considered a black widow system.Comment: Accepted for publication in Monthly Notices of the Royal Astronomical
Society. 15 pages, 7 Figures. Underlying data available at
https://zenodo.org/record/565306
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