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Gif-sur-Yvette, France

Ambainis A.,University of Latvia | Lee T.,SPMS | Lee T.,National University of Singapore | Balodis K.,University of Latvia | And 4 more authors.
Proceedings of the Annual ACM Symposium on Theory of Computing | Year: 2016

In 1986, Saks and Wigderson conjectured that the largest separation between deterministic and zero-error randomized query complexity for a total boolean function is given by the function f on n = 2k bits defined by a complete binary tree of NAND gates of depth k, which achieves Ro(f) = O(D(f)07537...). We show this is false by giving an example of a total boolean function f on n bits whose deterministic query complexity is Ω(n/log(n)) while its zero-error randomized query complexity is Õ(√n). We further show that the quantum query complexity of the same function is Õ(n1/4), giving the first example of a total function with a super-quadratic gap between its quantum and deterministic query complexities. We also construct a total boolean function gonn variables that has zero-error randomized query complexity Ω(n/log(n)) and bounded-error randomized query complexity R(g) = Õ(√n). This is the first super-linear separation between these two complexity measures. The exact quantum query complexity of the same function is Q E (g) = Õ(√n). These functions show that the relations D(f) = O(R1(f)2) and Ro(f) = Õ(R(f)2) are optimal, up to poly-logarithmic factors. Further variations of these functions give additional separations between other query complexity measures: a cubic separation between Q and Ro, a 3/2-power separation between Qe and R, and a 4th power separation between approximate degree and bounded-error randomized query complexity. All of these examples are variants of a function recently introduced by Göos, Pitassi, and Watson which they used to separate the unambiguous 1-certificate complexity from deterministic query complexity and to resolve the famous Clique versus Independent Set problem in communication complexity.

Patriarca-Almeida J.H.,CINTESIS | Santos B.,SPMS | Cruz-Correia R.J.,CINTESIS
Proceedings of CBMS 2013 - 26th IEEE International Symposium on Computer-Based Medical Systems | Year: 2013

The OPTIM project aims to optimize the graphical user interface of an electronic health record (EHR) by predicting clinical documents' relevance and provide a ranked list of relevant documents for the given user at a certain time. In this paper we will describe part of the system architecture pertaining to report retrieval and relevance assignment, focusing on the optimization of an agent based report retrieval system (MAID) using the webservice layer of the OPTIM project. The prototype of MAID using the optimized retrieval was tested in a simulated environment. In the executed simulations the classifier was able to rate 10 reports per second. Including a report rating in the EHR interface based on clinical relevance calculated by mathematical models can potentially improve the usability of the EHR. © 2013 IEEE.

Santos B.,SPMS | Rodrigues P.,University of Porto | Cruz-Correia R.,University of Porto
Proceedings - IEEE Symposium on Computer-Based Medical Systems | Year: 2013

The goal of the OPTIM project is to optimize the graphical user interface of an electronic health record (EHR) by predicting clinical documents' relevance and provide a ranked list of relevant documents for the given user at a certain time. This paper describes the architecture of the relevance assignment and ranking prototype and some implementation issues. The prototype's design is based on two components: OPTIM Core, with logical representation, estimation server's integration and the webservice layer, and the OPTIM WebUI, with the user interface for presenting the results. The prototype was tested in integration with an EHR using a simulated environment. The results were encouraging but yet they revealed a certain lack of security (confidentiality). It has now the capacity of rating 10 documents per second. Nonetheless, the integration of features such as rating clinical relevance based on mathematical models can be included in existing EHR potentially improving their usability. © 2013 IEEE.

Hamd W.,CNRS Laboratory of Condensed Matter Chemistry, Paris | Cobo S.,CNRS Chemistry and Biology of Metals Laboratory | Fize J.,CNRS Chemistry and Biology of Metals Laboratory | Baldinozzi G.,SPMS | And 8 more authors.
Physical Chemistry Chemical Physics | Year: 2012

This work reports a facile and cost-effective method for synthesizing photoactive α-Fe 2O 3 films as well as their performances when used as photoanodes for water oxidation. Transparent α-Fe 2O 3 mesoporous films were fabricated by template-directed sol-gel chemistry coupled with the dip-coating approach, followed by annealing at various temperatures from 350 °C to 750 °C in air. α-Fe 2O 3 films were characterized by X-ray diffraction, XPS, FE-SEM and electrochemical measurements. The photoelectrochemical performance of α-Fe 2O 3 photoanodes was characterized and optimized through the deposition of Co-based co-catalysts via different methods (impregnation, electro-deposition and photo-electro-deposition). Interestingly, the resulting hematite films heat-treated at relatively low temperature (500 °C), and therefore devoid of any extrinsic dopant, achieve light-driven water oxidation under near-to-neutral (pH = 8) aqueous conditions after decoration with a Co catalyst. The onset potential is 0.75 V vs. the reversible hydrogen electrode (RHE), thus corresponding to 450 mV light-induced underpotential, although modest photocurrent density values (40 μA cm -2) are obtained below 1.23 V vs. RHE. These new materials with a very large interfacial area in contact with the electrolyte and allowing for a high loading of water oxidation catalysts open new avenues for the optimization of photo-electrochemical water splitting. © 2012 the Owner Societies.

Baldinozzi G.,SPMS | Muller G.,CNRS Laboratory of Condensed Matter Chemistry, Paris | Laberty-Robert C.,CNRS Laboratory of Condensed Matter Chemistry, Paris | Gosset D.,SPMS | And 2 more authors.
Journal of Physical Chemistry C | Year: 2012

Nanocrystals growth mechanism embedded into mesoporous thin films has been determined directly from grazing incidence X-ray diffraction data. We have shown, for the first time, that surface capillary forces control the growth mechanism of nanocrystals into these nanoarchitectures. Moreover, these data allow an estimation of the surface tension of the nanocrystals organized into a 3-D nanoarchitecture. The analysis of the variations in the strain field of these nanocrystals gives information on the evolution of the microstructure of these mesoporous films, that is, the contacts among nanocrystals. This work represents the first application of grazing incidence X-ray for understanding stability and performances of mesoporous thin films. This approach can be used to understand the structural stability of these nanoarchitectures at high temperature. © 2012 American Chemical Society.

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