335 research outputs found
My Matter
An interview with the writer, financial technologist and author of Blank Swan, Elie Ayache by artist Roman Vasseur on the ramifications for the visual arts of Ayache’s work on probability, contingency and matter in the financial markets
Information-Theoretic Active Learning for Content-Based Image Retrieval
We propose Information-Theoretic Active Learning (ITAL), a novel batch-mode
active learning method for binary classification, and apply it for acquiring
meaningful user feedback in the context of content-based image retrieval.
Instead of combining different heuristics such as uncertainty, diversity, or
density, our method is based on maximizing the mutual information between the
predicted relevance of the images and the expected user feedback regarding the
selected batch. We propose suitable approximations to this computationally
demanding problem and also integrate an explicit model of user behavior that
accounts for possible incorrect labels and unnameable instances. Furthermore,
our approach does not only take the structure of the data but also the expected
model output change caused by the user feedback into account. In contrast to
other methods, ITAL turns out to be highly flexible and provides
state-of-the-art performance across various datasets, such as MIRFLICKR and
ImageNet.Comment: GCPR 2018 paper (14 pages text + 2 pages references + 6 pages
appendix
Hepatocellular carcinoma in hepatitis-negative patients with thalassemia intermedia: a closer look at the role of siderosis
Abstract Patients with thalassemia are often exposed to several risk factors for developing hepatocellular carcinoma (HCC) due to their repeated transfusions. However, even transfusion-independent patients with thalassemia intermedia (TI) can develop HCC, which is mainly attributed to a state of iron overload. We report here two cases and review the literature for the association between TI and HCC. Along with our cases, a total of 36 cases of HCC in thalassemic patients were reported in the literature. Of these, 22 (61%) were TI patients with 6 (27%) of them being hepatitis B and C negative. There was no consistency in their characteristics; therefore, we recommended screening thresholds for HCC in TI patients based on their total liver iron concentration (LIC)
Off-axis electron holography of bacterial cells and magnetic nanoparticles in liquid
The mapping of electrostatic potentials and magnetic fields in liquids usingelectron holography has been considered to be unrealistic. Here, we showthat hydrated cells ofMagnetospirillum magneticumstrain AMB-1 and assem-blies of magnetic nanoparticles can be studied using off-axis electronholography in a fluid cell specimen holder within the transmission electronmicroscope. Considering that the holographic object and reference waveboth pass through liquid, the recorded electron holograms show sufficientinterference fringe contrast to permit reconstruction of the phase shift ofthe electron wave and mapping of the magnetic induction from bacterialmagnetite nanocrystals. We assess the challenges of performingin situmagne-tization reversal experiments using a fluid cell specimen holder, discussapproaches for improving spatial resolution and specimen stability, and outlinefuture perspectives for studying scientific phenomena, ranging from interpar-ticle interactions in liquids and electrical double layers at solid–liquidinterfaces to biomineralization and the mapping of electrostatic potentialsassociated with protein aggregation and folding
An optimal series expansion of the multiparameter fractional Brownian motion
We derive a series expansion for the multiparameter fractional Brownian
motion. The derived expansion is proven to be rate optimal.Comment: 21 pages, no figures, final version, to appear in Journal of
Theoretical Probabilit
Retarding Sub- and Accelerating Super-Diffusion Governed by Distributed Order Fractional Diffusion Equations
We propose diffusion-like equations with time and space fractional
derivatives of the distributed order for the kinetic description of anomalous
diffusion and relaxation phenomena, whose diffusion exponent varies with time
and which, correspondingly, can not be viewed as self-affine random processes
possessing a unique Hurst exponent. We prove the positivity of the solutions of
the proposed equations and establish the relation to the Continuous Time Random
Walk theory. We show that the distributed order time fractional diffusion
equation describes the sub-diffusion random process which is subordinated to
the Wiener process and whose diffusion exponent diminishes in time (retarding
sub-diffusion) leading to superslow diffusion, for which the square
displacement grows logarithmically in time. We also demonstrate that the
distributed order space fractional diffusion equation describes super-diffusion
phenomena when the diffusion exponent grows in time (accelerating
super-diffusion).Comment: 11 pages, LaTe
Rushes summarization by IRIM consortium: redundancy removal and multi-feature fusion
International audienceIn this paper, we present the first participation of a consortium of French laboratories, IRIM, to the TRECVID 2008 BBC Rushes Summarization task. Our approach resorts to video skimming. We propose two methods to reduce redundancy, as rushes include several takes of scenes. We also take into account low and midlevel semantic features in an ad-hoc fusion method in order to retain only significant content
Fractional oscillator process with two indices
We introduce a new fractional oscillator process which can be obtained as
solution of a stochastic differential equation with two fractional orders.
Basic properties such as fractal dimension and short range dependence of the
process are studied by considering the asymptotic properties of its covariance
function. The fluctuation--dissipation relation of the process is investigated.
The fractional oscillator process can be regarded as one-dimensional fractional
Euclidean Klein-Gordon field, which can be obtained by applying the Parisi-Wu
stochastic quantization method to a nonlocal Euclidean action. The Casimir
energy associated with the fractional field at positive temperature is
calculated by using the zeta function regularization technique.Comment: 32 page
Optical properties of an effective one-band Hubbard model for the cuprates
We study the Cu and O spectral density of states and the optical conductivity
of CuO_2 planes using an effective generalized one-band Hubbard model derived
from the extended three-band Hubbard model. We solve exactly a square cluster
of 10 unit cells and average the results over all possible boundary conditions,
what leads to smooth functions of frequency. Upon doping, the Fermi energy
jumps to Zhang-Rice states which are connected to the rest of the valence band
(in contrast to an isolated new band in the middle of the gap). The transfer of
spectral weight depends on the parameters of the original three-band model not
only through the one-band effective parameters but also through the relevant
matrix elements. We discuss the evolution of the gap upon doping. The optical
conductivity of the doped system shows a mid-infrared peak due to intraband
transitions, a pseudogap and a high frequency part related to interband
transitions. Its shape and integrated weight up to a given frequency (including
the Drude weight) agree qualitatively with experiments in the cuprates for low
to moderate doping levels, but significant deviations exist for doping .Comment: 11 pages (tex), 14 figures (ps
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