Online change detection in exponential families with unknown parameters

International audienceThis paper studies online change detection in exponential families when both the parameters before and after change are unknown. We follow a standard statistical approach to sequential change detection with generalized likelihood ratio test statistics. We interpret these statistics within the framework of information geometry, hence providing a unified view of change detection for many common statistical models and corresponding distance functions. Using results from convex duality, we also derive an efficient scheme to compute the exact statistics sequentially, which allows their use in online settings where they are usually approximated for the sake of tractability. This is applied to real-world datasets of various natures, including onset detection in audio signals

Analysis of clinically relevant single-nucleotide polymorphisms by use of microelectronic array technology

BACKGROUND: Microelectronic DNA chip devices represent an emerging technology for genotyping. We developed methods for detection of single-nucleotide polymorphisms (SNPs) in clinically relevant genes. METHODS: Primer pairs, with one containing a 5'-biotin group, were used to PCR-amplify the region encompassing the SNP to be interrogated. After denaturation, the biotinylated strand was electronically targeted to discrete sites on streptavidin-coated gel pads surfaces by use of a Nanogen Molecular Workstation. Allele-specific dye-labeled oligonucleotide reporters were used for detection of wild-type and variant sequences. Methods were developed for SNPs in genes, including factor VII, beta-globin, and the RET protooncogene. We genotyped 331 samples for five DNA variations in the factor VII gene, >600 samples from patients with beta-thalassemia, and 15 samples for mutations within the RET protooncogene. All samples were previously typed by various methods, including DNA sequence analysis, allele-specific PCR, and/or restriction enzyme digestion of PCR products. RESULTS: Analysis of amplified DNA required 4-6 h. After mismatched DNA was removed, signal-to-noise ratios were >5. More than 940 samples were typed with the microelectronic array platform, and results were totally concordant with results obtained previously by other genotyping methods. CONCLUSIONS: The described protocols detect SNPs of clinical interest with results comparable to those of other genotyping methods

Radiation hydrodynamics with backscatter and beam spray in gas filled hohlraum experiments at the National Ignition Facility

Several experiments using either CO$_{2}$ or propane gas filled halfraums [i.e. hohlraums with a single laser entry hole (LEH)] have been shot at the National Ignition Facility (NIF) in a joint Los Alamos/Livermore collaboration. The experiments have been modeled by the Lasnex code. The possibility of beam spray due to filamentation of the incident laser beam is assessed through simulations which parametrically decrease the f-number of the beam at times of high intensity. The uncertainty in heat transport is evaluated through parametric variations in the electron thermal flux limit (fe). Each calculation in the resulting two parameter set is post-processed to simulate outputs which can be compared with Dante detector results for the soft X-ray flux through the LEH, and gated, framed images of hard X-rays (FXI) through the hohlraum side walls. Simulations which well match the data for both gases indicate that the laser energy is penetrating the gas filled hohlraum even towards the end of the pulse. This suggests that the gas fill is useful in keeping the hohlraum open to laser energy throughout the pulse