8,845 research outputs found
Searching for Ground Truth: a stepping stone in automating genre classification
This paper examines genre classification of documents and
its role in enabling the effective automated management of digital documents by digital libraries and other repositories. We have previously presented genre classification as a valuable step toward achieving automated extraction of descriptive metadata for digital material. Here, we present results from experiments using human labellers, conducted to assist in genre characterisation and the prediction of obstacles which need to be overcome by an automated system, and to contribute to the process of creating a solid testbed corpus for extending automated genre classification and testing metadata extraction tools across genres. We also describe the performance of two classifiers based on image and stylistic modeling features in labelling the data resulting from the agreement of three human labellers across fifteen genre classes.
The efficient computation of transition state resonances and reaction rates from a quantum normal form
A quantum version of a recent formulation of transition state theory in {\em
phase space} is presented. The theory developed provides an algorithm to
compute quantum reaction rates and the associated Gamov-Siegert resonances with
very high accuracy. The algorithm is especially efficient for
multi-degree-of-freedom systems where other approaches are no longer feasible.Comment: 4 pages, 3 figures, revtex
High-Yield of Memory Elements from Carbon Nanotube Field-Effect Transistors with Atomic Layer Deposited Gate Dielectric
Carbon nanotube field-effect transistors (CNT FETs) have been proposed as
possible building blocks for future nano-electronics. But a challenge with CNT
FETs is that they appear to randomly display varying amounts of hysteresis in
their transfer characteristics. The hysteresis is often attributed to charge
trapping in the dielectric layer between the nanotube and the gate. This study
includes 94 CNT FET samples, providing an unprecedented basis for statistics on
the hysteresis seen in five different CNT-gate configurations. We find that the
memory effect can be controlled by carefully designing the gate dielectric in
nm-thin layers. By using atomic layer depositions (ALD) of HfO and
TiO in a triple-layer configuration, we achieve the first CNT FETs with
consistent and narrowly distributed memory effects in their transfer
characteristics.Comment: 6 pages, 3 figures; added one reference, text reformatted with
smaller addition
Decoding the multifaceted HIV-1 virus-host interactome
Recently in BMC Medical Genomics, Tozeren and colleagues have uncovered virus-host interactions by searching for conserved peptide motifs in HIV and human proteins. Their computational model provides a novel perspective in the interpretation of high-throughput data on the HIV-host interactome
The interaction between colloids in polar mixtures above Tc
We calculate the interaction potential between two colloids immersed in an
aqueous mixture containing salt near or above the critical temperature. We find
an attractive interaction far from the coexistence curve due to the combination
of preferential solvent adsorption at the colloids' surface and preferential
ion solvation. We show that the ion-specific interaction strongly depends on
the amount of salt added as well as on the mixture composition. Our results are
in accord with recent experiments. For a highly antagonistic salt of
hydrophilic anions and hydrophobic cations, a repulsive interaction at an
intermediate inter-colloid distance is predicted even though both the
electrostatic and adsorption forces alone are attractive.Comment: 9 pages, 6 figure
Effective Potential and Thermodynamics for a Coupled Two-Field Bose Gas Model
We study the thermodynamics of a two-species homogeneous and dilute Bose gas
that is self-interacting and quadratically coupled to each other. We make use
of field theoretical functional integral techniques and evaluate the one-loop
finite temperature effective potential for this system considering the
resummation of the leading order temperature dependent as well as infrared
contributions. The symmetry breaking pattern associated to the model is then
studied by considering different values of self and inter-species couplings. We
pay special attention to the eventual appearance of reentrant phases and/or
shifts in the observed critical temperatures as compared to the monoatomic
(one-field Bose) case.Comment: 21 pages, 4 eps figure
UrQMD calculations of two-pion HBT correlations in p+p and Pb+Pb collisions at LHC energies
Two-pion Hanbury-Brown-Twiss (HBT) correlations for p+p and central Pb+Pb
collisions at the Large-Hadron-Collider (LHC) energies are investigated with
the ultra-relativistic quantum molecular dynamics model combined with a
correlation afterburner. The transverse momentum dependence of the
Pratt-Bertsch HBT radii , , and is extracted from
a three-dimensional Gaussian fit to the correlator in the longitudinal
co-moving system. In the p+p case, the dependence of correlations on the
charged particle multiplicity and formation time is explored and the data
allows to constrain the formation time in the string fragmentation to fm/c. In the Pb+Pb case, it is found that is overpredicted
by nearly 50%. The LHC results are also compared to data from the STAR
experiment at RHIC. For both energies we find that the calculated
ratio is always larger than data, indicating that the
emission in the model is less explosive than observed in the data.Comment: 9 pages, 4 figures, 1 table. Talk given by Qingfeng Li at the 11th
International Conference on Nucleus-Nucleus Collisions (NN2012), San Antonio,
Texas, USA, May 27-June 1, 2012. To appear in the NN2012 Proceedings in
Journal of Physics: Conference Series (JPCS
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Developing Children's Oral Health Assessment Toolkits Using Machine Learning Algorithm.
ObjectivesEvaluating children's oral health status and treatment needs is challenging. We aim to build oral health assessment toolkits to predict Children's Oral Health Status Index (COHSI) score and referral for treatment needs (RFTN) of oral health. Parent and Child toolkits consist of short-form survey items (12 for children and 8 for parents) with and without children's demographic information (7 questions) to predict the child's oral health status and need for treatment.MethodsData were collected from 12 dental practices in Los Angeles County from 2015 to 2016. We predicted COHSI score and RFTN using random Bootstrap samples with manually introduced Gaussian noise together with machine learning algorithms, such as Extreme Gradient Boosting and Naive Bayesian algorithms (using R). The toolkits predicted the probability of treatment needs and the COHSI score with percentile (ranking). The performance of the toolkits was evaluated internally and externally by residual mean square error (RMSE), correlation, sensitivity and specificity.ResultsThe toolkits were developed based on survey responses from 545 families with children aged 2 to 17 y. The sensitivity and specificity for predicting RFTN were 93% and 49% respectively with the external data. The correlation(s) between predicted and clinically determined COHSI was 0.88 (and 0.91 for its percentile). The RMSEs of the COHSI toolkit were 4.2 for COHSI (and 1.3 for its percentile).ConclusionsSurvey responses from children and their parents/guardians are predictive for clinical outcomes. The toolkits can be used by oral health programs at baseline among school populations. The toolkits can also be used to quantify differences between pre- and post-dental care program implementation. The toolkits' predicted oral health scores can be used to stratify samples in oral health research.Knowledge transfer statementThis study creates the oral health toolkits that combine self- and proxy- reported short forms with children's demographic characteristics to predict children's oral health and treatment needs using Machine Learning algorithms. The toolkits can be used by oral health programs at baseline among school populations to quantify differences between pre and post dental care program implementation. The toolkits can also be used to stratify samples according to the treatment needs and oral health status
Direct observation of charge inversion by multivalent ions as a universal electrostatic phenomenon
We have directly observed reversal of the polarity of charged surfaces in
water upon the addition of tri- and quadrivalent ions using atomic force
microscopy. The bulk concentration of multivalent ions at which charge
inversion reversibly occurs depends only very weakly on the chemical
composition, surface structure, size and lipophilicity of the ions, but is
dominated by their valence. These results support the theoretical proposal that
spatial correlations between ions are the driving mechanism behind charge
inversion.Comment: submitted to PRL, 26-04-2004 Changed the presentation of the theory
at the end of the paper. Changed small error in estimate of prefactor ("w" in
first version) of equation
On the Phenomenology of Hydrodynamic Shear Turbulence
The question of a purely hydrodynamic origin of turbulence in accretion disks
is reexamined, on the basis of a large body of experimental and numerical
evidence on various subcritical (i.e., linearly stable) hydrodynamic flows.
One of the main points of this paper is that the length scale and velocity
fluctuation amplitude which are characteristic of turbulent transport in these
flows scale like , where is the minimal Reynolds number for
the onset of fully developed turbulence. From this scaling, a simple
explanation of the dependence of with relative gap width in subcritical
Couette-Taylor flows is developed. It is also argued that flows in the shearing
sheet limit should be turbulent, and that the lack of turbulence in all such
simulations performed to date is most likely due to a lack of resolution, as a
consequence of the effect of the Coriolis force on the large scale fluctuations
of turbulent flows.
These results imply that accretion flows should be turbulent through
hydrodynamic processes. If this is the case, the Shakura-Sunyaev
parameter is constrained to lie in the range in accretion
disks, depending on unknown features of the mechanism which sustains
turbulence. Whether the hydrodynamic source of turbulence is more efficient
than the MHD one where present is an open question.Comment: 31 pages, 3 figures. Accepted for publication in Ap
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