Positive semi-definite embedding for dimensionality reduction and out-of-sample extensions

In machine learning or statistics, it is often desirable to reduce the dimensionality of a sample of data points in a high dimensional space $\mathbb{R}^d$. This paper introduces a dimensionality reduction method where the embedding coordinates are the eigenvectors of a positive semi-definite kernel obtained as the solution of an infinite dimensional analogue of a semi-definite program. This embedding is adaptive and non-linear. A main feature of our approach is the existence of a non-linear out-of-sample extension formula of the embedding coordinates, called a projected Nystr\"om approximation. This extrapolation formula yields an extension of the kernel matrix to a data-dependent Mercer kernel function. Our empirical results indicate that this embedding method is more robust with respect to the influence of outliers, compared with a spectral embedding method.Comment: 16 pages, 5 figures. Improved presentatio

Measuring the one-particle excitations of ultracold fermionic atoms by stimulated Raman spectroscopy

We propose a Raman spectroscopy technique which is able to probe the one-particle Green's function, the Fermi surface, and the quasiparticles of a gas of strongly interacting ultracold atoms. We give quantitative examples of experimentally accessible spectra. The efficiency of the method is validated by means of simulated images for the case of a usual Fermi liquid as well as for more exotic states: specific signatures of e.g. a d-wave pseudo-gap are clearly visible.Comment: 5 pages, 3 figures accepted for publication at Phys. Rev. Letter

Beak colour dynamically signals changes in fasting status and parasite loads in king penguins

This research was funded by the French Polar Institute (IPEV–Research Program 119) and the French National Centre for Scientific Research (CNRS-INEE). Field logistic support was provided by Terres Australes et Antarctiques Françaises. Q.S. was funded by a doctoral fellowship from the Ministère Français de l’Education Supérieur et de la Recherche. We thank all over-wintering assistants: Benoit Gineste, Sylvia Pardonnet, Laureline Durand, Emilie Lefol and Hédi Saadaoui for field work and Emilio Rojas for helpful discussion on the analyses. We apologize to our stick insect (Carausius morosus) for bearing with VAV’s inquisitive curiosity during our debates on color ornaments in king penguins. We sincerely thank the editor and 2 anonymous reviewers for their helpful comments on a previous version of the paper.Peer reviewedPostprin

The oxidative debt of fasting : evidence for short to medium-term costs of advanced fasting in adult king penguins

This research was funded by the French Polar Institute (IPEV–Research Program 119) and the French National Centre for Scientific Research (CNRS-INEE). We are especially grateful to Dominic L. Cram and one anonymous reviewer for helpful comments on the paper. Field logistic support was provided by Terres Australes et Antarctiques Françaises. QS was funded by a doctoral fellowship from the Ministère Français de l’Education Supérieur et de la Recherche.Peer reviewedPublisher PD

Some remarks on quasi-Hermitian operators

A quasi-Hermitian operator is an operator that is similar to its adjoint in some sense, via a metric operator, i.e., a strictly positive self-adjoint operator. Whereas those metric operators are in general assumed to be bounded, we analyze the structure generated by unbounded metric operators in a Hilbert space. Following our previous work, we introduce several generalizations of the notion of similarity between operators. Then we explore systematically the various types of quasi-Hermitian operators, bounded or not. Finally we discuss their application in the so-called pseudo-Hermitian quantum mechanics.Comment: 18page

Détection hors contexte des émotions à partir du contenu linguistique d'énoncés oraux : le système EmoLogus

The ANR Emotirob project aims at detecting emotions in an original application context: realizing an emotional companion robot for weakened children. This paper presents a system which aims at characterizing emotions by only considering linguistic content. It is based on the assumption that emotions can be compound: simple lexical words have an intrinsic emotional value, while verbal and adjectival predicates act as a function on the emotional values of their arguments. The paper describes the algorithm of compositional computation of the emotion and the lexical emotional norm used by this algorithm. A quantitative and qualitative analysis of the differences between system outputs and expert annotations is given, which shows satisfactory results, with a good detection of emotional valency in 90.0% of the test utterances

Interaction-induced impeding of decoherence and anomalous diffusion

We study how the interplay of dissipation and interactions affects the dynamics of a bosonic many-body quantum system. In the presence of both dissipation and strongly repulsive interactions, observables such as the coherence and the compressibility display three dynamical regimes: an initial exponential variation followed by a power-law regime and finally a slow exponential convergence to their asymptotic values corresponding to the infinite temperature state. These very long-time scales arise as dissipation forces the population of states disfavored by interactions. The long-time, strong coupling dynamics are understood by performing a mapping onto a classical diffusion process displaying non-Brownian behavior. While both dissipation and strong interactions tend to suppress coherence when acting separately, we find that strong interaction impedes the decoherence process generated by the dissipation.Comment: 5 pages, 3 figure

Emologus - A Compositional Model of Emotion Detection based on the Propositionnal Content of Spoken Utterances

International audienceThe ANR EmotiRob project aims at detecting emotions in an original application context: realizing an emotional companion robot for weakened children. This paper presents a system which aims at characterizing emotions by only considering the linguistic content of utterances. It is based on the assumption of compositionality: simple lexical words have an intrinsic emotional value, while verbal and adjectival predicates act as a function on the emotional values of their arguments. The paper describes the semantic component of the system, the algorithm of compositional computation of the emotion value and the lexical emotional norm used by this algorithm. A quantitative and qualitative analysis of the dierences between system outputs and expert annotations is given, which shows satisfactory results, with the right detection of emotional valency in 90% of the test utterances

Sensory and motor neuronopathy in a patient with the A382P TDP-43 mutation

Patients with TARDBP mutations have so far been classified as ALS, sometimes with frontal lobe dysfunction. A 66-year-old patient progressively developed a severe sensory disorder, followed by a motor disorder, which evolved over nine years. Symptoms started in the left hand and slowly involved the four limbs. Investigations were consistent with a mixed sensory and motor neuronopathy. A heterozygous change from an alanine to a proline at amino acid 382 was identified in exon 6 of the TARDPB gene (p.A382P). This case expands the phenotypic spectrum associated with mutations in the TARDBP gene and shows that sensory neurons can be severely damaged early in the course of the disease, following a propagating process, with an orderly progression from a focal starting point. A combination of severe sensory and motor neuronopathy is rarely encountered in clinical practice. The possibility of an A382P TDP-43 mutation should be considered in patients with such an association

Magnetic Screening of NbN Multilayers Samples

6 pagesInternational audienceIn 2006 Gurevich proposed to use nanoscale layers of superconducting materials with high values of Hc > Hc^Nb for magnetic shielding of bulk niobium to increase the breakdown magnetic field inside SC RF cavities [1]. We have deposited high quality "model" samples by magnetron sputtering on monocrystalline sapphire substrates. A 250 nm layer of niobium figures the bulk Nb. It was coated with a single and multi-stacks of NbN layers (25 or12 nm) separated by 15 nm MgO barriers, and characterized by X-Ray reflectivity and DC transport measurements. DC or AC measurement of HC1 is an important goal for multilayer evaluation during the sample evaluation phase. A clear increase of HC1 at low frequency is promising indication since HC1 is expected to increase with frequency (see e.g. [2] and references therein). We have measured the first penetration field (HP~HC1) on DC magnetization curves in a SQUID system. HP of NbN covered sample is increased compared to Nb alone. We have also developed a set-up that allows measuring a large range of field and temperature with a local probe method based on 3rd harmonic analysis. We have confirmed the screening behavior of a single 25 nm NbN layer placed on the top of a Nb Layer