604 research outputs found
Nonparametric Bayesian Mixed-effect Model: a Sparse Gaussian Process Approach
Multi-task learning models using Gaussian processes (GP) have been developed
and successfully applied in various applications. The main difficulty with this
approach is the computational cost of inference using the union of examples
from all tasks. Therefore sparse solutions, that avoid using the entire data
directly and instead use a set of informative "representatives" are desirable.
The paper investigates this problem for the grouped mixed-effect GP model where
each individual response is given by a fixed-effect, taken from one of a set of
unknown groups, plus a random individual effect function that captures
variations among individuals. Such models have been widely used in previous
work but no sparse solutions have been developed. The paper presents the first
sparse solution for such problems, showing how the sparse approximation can be
obtained by maximizing a variational lower bound on the marginal likelihood,
generalizing ideas from single-task Gaussian processes to handle the
mixed-effect model as well as grouping. Experiments using artificial and real
data validate the approach showing that it can recover the performance of
inference with the full sample, that it outperforms baseline methods, and that
it outperforms state of the art sparse solutions for other multi-task GP
formulations.Comment: Preliminary version appeared in ECML201
Parameter estimation of a transformer with saturation using inrush measurements
a b s t r a c t This paper presents a method to compute the parameters of a transformer model with saturation using the voltage and current waveforms of an inrush test and a no-load test. The transformer is modeled with their electric and magnetic equivalent circuits and a single-valued function that characterizes its non-linear magnetic behavior. A 3-kVA single-phase transformer and a 5-kVA three-phase three-legged transformer have been tested in the laboratory. The method to obtain the parameters of the non-linear flux-current relation that characterize the saturation has been described in the paper. The analytical function used to adjust the experimental measurements fits them very well
Oral manifestations of Wolf-Hirschhorn syndrome: genotype-phenotype correlation analysis
Background: Wolf-Hirschhorn syndrome (WHS) is a rare disease caused by deletion in
the distal moiety of the short arm of chromosome 4. The objectives of this study were to report
the most representative oral findings of WHS, relate them with other clinical characteristics of
the disease, and establish possible phenotype-genotype correlation. Methods: The study was
conducted at 6 reference centers distributed throughout Spain during 2018–2019. The study
group consisted of 31 patients with WHS who underwent a standardized oral examination.
Due to behavioral reasons, imaging studies were performed on only 11 of the children 6 years
of age or older. All participants had previously undergone a specific medical examination
for WHS, during which anatomical, functional, epilepsy-related, and genetic variables were
recorded. Results: The most prevalent oral manifestations were delayed tooth eruption (74.1%),
bruxism (64.5%), dental agenesis (63.6%), micrognathia (60.0%), oligodontia (45.5%), and
downturned corners of the mouth (32.3%). We detected strong correlation between psychomotor
delay and oligodontia (p = 0.008; Cramér’s V coefficient, 0.75). The size of the deletion was
correlated in a statistically significant manner with the presence of oligodontia (p = 0.009 ;
point-biserial correlation coefficient, 0.75). Conclusion: Certain oral manifestations prevalent in
WHS can form part of the syndrome’s phenotypic variability. A number of the characteristics
of WHS, such as psychomotor delay and epilepsy, are correlated with oral findings such
as oligodontia and bruxism. Although most genotype-phenotype correlations are currently
unknown, most of them seem to be associated with larger deletions, suggesting that some
oral-facial candidate genes might be outside the critical WHS region, indicating that WHS is a
contiguous gene syndrome
Wave-induced extreme water levels in the Puerto Morelos fringing reef lagoon
Wave-induced extreme water levels in the Puerto Morelos fringing reef lagoon are investigated by means of a phase-resolving non-hydrostatic wave model (SWASH). This model solves the nonlinear shallow water equations including non-hydrostatic pressure. The one-dimensional version of the model is implemented in order to investigate wave transformation in fringing reefs. Firstly, the numerical model is validated with (i) laboratory experiments conducted on a physical model (Demirbilek et al., 2007)and (ii) field observations (Coronado et al., 2007). Numerical results show good agreement with both experimental and field data. The comparison against the physical model results, for energetic wave conditions, indicates that high- and low-frequency wave transformation is well reproduced. Moreover, extreme water-level conditions measured during the passage of Hurricane Ivan in Puerto Morelos are also estimated by the numerical tool. Subsequently, the model is implemented at different along-reef locations in Puerto Morelos. Extreme water levels, wave-induced setup, and infragravity wave energy are estimated inside the reef lagoon for different storm wave conditions (<i>H</i><sub>s</sub> >2 m). The numerical results revealed a strong correlation between the offshore sea-swell wave energy and the setup. In contrast, infragravity waves are shown to be the result of a more complex pattern which heavily relies on the reef geometry. Indeed, the southern end of the reef lagoon provides evidence of resonance excitation, suggesting that the reef barrier may act as either a natural flood protection morphological feature, or as an inundation hazard enhancer depending on the incident wave conditions
Low-Temperature Spin Diffusion in a Spin-Polarized Fermi Gas
We present a finite temperature calculation of the transverse spin-diffusion
coefficient, , in a dilute degenerate Fermi gas in the presence of a
small external magnetic field, . While the longitudinal diffusion
coefficient displays the conventional low-temperature Fermi-liquid behavior,
, the corresponding results for show three
separate regimes: (a) for ; (b) , for and large spin-rotation
parameter , and (c) for and . Our results are qualitatively consistent with the available
experimental data in weakly spin-polarized and mixtures.Comment: 13 pages, REVTEX, 3 figures available upon request, RU-94-4
Linear forms and quadratic uniformity for functions on
A very useful fact in additive combinatorics is that analytic expressions
that can be used to count the number of structures of various kinds in subsets
of Abelian groups are robust under quasirandom perturbations, and moreover that
quasirandomness can often be measured by means of certain easily described
norms, known as uniformity norms. However, determining which uniformity norms
work for which structures turns out to be a surprisingly hard question. In
[GW09a] and [GW09b, GW09c] we gave a complete answer to this question for
groups of the form , provided is not too small. In
, substantial extra difficulties arise, of which the most
important is that an "inverse theorem" even for the uniformity norm
requires a more sophisticated (local) formulation. When is
prime, is not rich in subgroups, so one must use regular Bohr
neighbourhoods instead. In this paper, we prove the first non-trivial case of
the main conjecture from [GW09a].Comment: 66 page
Refining seismic parameters in low seismicity areas by 3D trenching: The Alhama de Murcia fault, SE Iberia.
Three-dimensional paleoseismology in strike-slip faults with slip rates less than 1 mm per year involves a great methodological challenge. We adapted 3D trenching to track buried channels offset by the Alhama de Murcia seismogenic left-lateral strike-slip fault (SE Iberia). A fault net slip of 0.9 +/- 0.1 mm/yr was determined using statistical analysis of piercing lines for one buried channel, whose age is constrained between 15.2 +/- 1.1 ka and 21.9-22.3 cal BP. This value is larger and more accurate than the previously published slip rates for this fault: The minimum number of five paleo-earthquakes identified since the deposition of dated layers suggests a maximum average recurrence interval of approximately 5 ka. The combination of both seismic parameters yields a maximum slip per event between 53 and 63 m. We show that accurately planned trenching strategies and data processing may be key to obtaining robust paleoseismic parameters in low seismicity areas. (C) 2016 Elsevier B.V. All rights reserved
Testicular germ-cell tumours and penile squamous cell carcinoma: Appropriate management makes the difference
Germ-cell tumours (GCT) of the testis and penile squamous cell carcinoma (PeSCC) are a rare and a very rare uro-genital cancers, respectively. Both tumours are well defined entities in terms of management, where specific recommendations - in the form of continuously up-to-dated guide lines-are provided. Impact of these tumour is relevant. Testicular GCT affects young, healthy men at the beginning of their adult life. PeSCC affects older men, but a proportion of these patients are young and the personal consequences of the disease may be devastating. Deviation from recommended management may be a reason of a significant prognostic worsening, as proper treatment favourably impacts on these tumours, dramatically on GCT and significantly on PeSCC. RARECAREnet data may permit to analyse how survivals may vary according to geographical areas, histology and age, leading to assume that non-homogeneous health-care resources may impact the cure and definitive outcomes. In support of this hypothesis, some epidemiologic datasets and clinical findings would indicate that survival may improve when appropriate treatments are delivered, linked to a different accessibility to the best health institutions, as a consequence of geographical, cultural and economic barriers. Finally, strong clues based on epidemiological and clinical data support the hypothesis that treatment delivered at reference centres or under the aegis of a qualified multi-institutional network is associated with a better prognosis of patients with these malignancies. The ERN EURACAN represents the best current European effort to answer this clinical need
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