A pseudo-R2 measure for selecting genomic markers with crossing hazards functions

<p>Abstract</p> <p>Background</p> <p>In genomic medical studies, one of the major objectives is to identify genomic factors with a prognostic impact on time-to-event outcomes so as to provide new insights into the disease process. Selection usually relies on statistical univariate indices based on the Cox model. Such model assumes proportional hazards (PH) which is unlikely to hold for each genomic marker.</p> <p>Methods</p> <p>In this paper, we introduce a novel pseudo-R²measure derived from a crossing hazards model and designed for the selection of markers with crossing effects. The proposed index is related to the score statistic and quantifies the extent of a genomic factor to separate patients according to their survival times and marker measurements. We also show the importance of considering genomic markers with crossing effects as they potentially reflect the complex interplay between markers belonging to the same pathway.</p> <p>Results</p> <p>Simulations show that our index is not affected by the censoring and the sample size of the study. It also performs better than classical indices under the crossing hazards assumption. The practical use of our index is illustrated in a lung cancer study. The use of the proposed pseudo-R²allows the identification of cell-cycle dependent genes not identified when relying on the PH assumption.</p> <p>Conclusions</p> <p>The proposed index is a novel and promising tool for selecting markers with crossing hazards effects.</p

PEKE, Probabilistic Encryption Key Exchange, 10 Years Later, Including the PEKEv1.25 Specifications

This document revisits the PEKE (Probabilistic Encryption Key Exchange) cryptosystem and proposes the enhanced PEKEv1.25 that performs a hash computation on the original PEKE output in order to improve the security assurance and to broaden the field of use. For a key establishment application where only the server side publishes a long-term public key and can adequately protect the private key counterpart from implementation attacks, we claim that PEKE is unsurpassed in security and efficiency, among the finite field arithmetic cryptosystems (e.g. RSA and finite field Diffie-Hellman). We use an original definition for the type of key encapsulation service provided by PEKE, hoping that this abstract definition captures the characteristics of the protocol and usage context. However, we only suggest that related security proofs are encouraging for the security of PEKE

Computing combustion noise by combining Large Eddy Simulation with analytical models for the propagation of waves through turbine blades

Two mechanisms control combustion noise generation as shown by Marble and Candel [1]: direct noise, in which acoustic waves propagate through the turbine stages and indirect noise, in which vorticity and/or entropy waves generate noise as they are convected through turbine stages. A method to calculate combustion-generated noise has been implemented in a tool called CHORUS. The method uses the Large eddy simulations of the combustion chamber obtained with the unstructured solver AVBP developed at CERFACS [2] and analytical models for the propagation through turbine stages. The propagation models [3] use the compact row hypothesis to write matching conditions between the inlet and the outlet of a turbine stage. Using numerical simulations, the validity of the analytical methods is studied and the errors made quantified