Unsupervised discovery of temporal sequences in high-dimensional datasets, with applications to neuroscience.

Identifying low-dimensional features that describe large-scale neural recordings is a major challenge in neuroscience. Repeated temporal patterns (sequences) are thought to be a salient feature of neural dynamics, but are not succinctly captured by traditional dimensionality reduction techniques. Here, we describe a software toolbox-called seqNMF-with new methods for extracting informative, non-redundant, sequences from high-dimensional neural data, testing the significance of these extracted patterns, and assessing the prevalence of sequential structure in data. We test these methods on simulated data under multiple noise conditions, and on several real neural and behavioral datas. In hippocampal data, seqNMF identifies neural sequences that match those calculated manually by reference to behavioral events. In songbird data, seqNMF discovers neural sequences in untutored birds that lack stereotyped songs. Thus, by identifying temporal structure directly from neural data, seqNMF enables dissection of complex neural circuits without relying on temporal references from stimuli or behavioral outputs

Current utility of the ankle-brachial index (ABI) in general practice: implications for its use in cardiovascular disease screening

Peripheral arterial disease (PAD) is a marker of systemic atherosclerosis and associated with a three to six fold increased risk of death from cardiovascular causes. Furthermore, it is typically asymptomatic and under-diagnosed; this has resulted in escalating calls for the instigation of Primary Care PAD screening via Ankle Brachial Index (ABI) measurement. However, there is limited evidence regarding the feasibility of this and if the requisite core skills and knowledge for such a task already exist within primary care. This study aimed to determine the current utility of ABI measurement in general practices across Wales, with consideration of the implications for its use as a cardiovascular risk screening tool

COMPTEL observations of the Virgo blazars 3C 273 and 3C 279

We report the main MeV properties (detections, light curves, spectra) of the Virgo blazars 3C 273 and 3C 279 which were derived from a consistent analysis of all COMPTEL Virgo observations between 1991 and 1997

COMPTEL observations of the blazars 3C 454.3 and CTA 102

We have analyzed the two blazars of 3C 454.3 and CTA 102 using all available COMPTEL data from 1991 to 1999. In the 10–30 MeV band, emission from the general direction of the sources is found at the 4σ-level, being consistent with contributions from both sources. Below 10 MeV only 3C 454.3 is significantly detected, with the strongest evidence (5.6 σ) in the 3–10 MeV band. Significant flux variability is not observed for both sources, while a low emission is seen most of the years in the 3–10 MeV light curve for 3C 454.3. Its time-averaged MeV spectrum suggests a power maximum between 3 to 10 MeV

Ultrasonic Bacscatter from Embedded Cylinders

Advanced composite materials present unique challenges for nondestructive evaluation of their material properties and state of health or damage. Stitches and other through-the-thickness reinforcements are becoming much more common because of their ability to give substantially improved three-dimensional strength to finished components. They also allow textile preforms to hold their shapes before and during resin transfer molding, and can be important in automated tow-placement processes. Ultrasonic testing of advanced composites is desirable before, during and after consolidation and curing in order to monitor both the initial fabrication and the eventual inevitable structural degradation as the composite structure ages. Unfortunately, the very stitches that improve the properties of the composites interfere with the usual inspection methods. This difficulty can be overcome, however, if the interaction of the probing ultrasonic radiation with the through-the-thickness reinforcements can be understood and quantified. In this paper we present the results of our recent study which has considered theoretically and experimentally the scattering of elastic waves from embedded cylindrical elastic scatterers. In particular, we have derived an exact and analytic, closed-form solution for the oblique polar backscatter from these structures and then have compared our theoretical results with ultrasonic immersion tank experiments conducted on wires, fibers and tows embedded in polymeric materials

Multilocus and interaction-based genome scan for alcoholism risk factors in Caucasian Americans: the COGA study

In this paper, we applied the nonparametric linkage regression approach to the Caucasian genome scan data from the Collaborative Study on the Genetics of Alcoholism to search for regions of the genome that exhibit evidence for linkage to putative alcoholism-predisposing genes. The multipoint single-locus model identified four regions of the genome with LOD scores greater than one. These regions were on 7p near D7S1790 (LOD = 1.31), two regions on 7q near D7S1870 (LOD = 1.15) and D7S1799 (LOD = 1.13) and 21q near D21S1440 and D21S1446 (LOD = 1.78). Jointly modeling these loci provided stronger evidence for linkage in each of these regions (LOD = 1.58 on 7q11, LOD = 1.61 on 11q23, and LOD = 1.95 on 21q22). The evidence for linkage tended to increase among pedigrees with earlier mean age of onset at 8q23 (p = 0.0016), 14q21 (p = 0.0079), and 18p12 (p = 0.0021) and with later mean age of onset at 4q35 (p = 0.0067) and 9p22 (p = 0.0008)

Molecular Phylogenetics of Neotropical Leafless Angraecinae (Orchidaceae): Re-Evaluation of Generic Concepts

Phylogenetic relationships of leafless Neotropical Angraecinae (Dendrophylax Rchb.f., Harrisella Fawc. & Rendle, Polyradicion Garay, and Campylocentrum Benth.) were estimated using combined nuclear (ITS nrDNA) and plastid (matK and trnL-F) data sets with African angraecoid taxa as outgroups. Results indicate that Harrisella, Polyradicion, and Campylocentrum filiforme (Sw.) Cogn. are embedded within Dendrophylax and should be included in Dendrophylax. This contrasts with earlier generic concepts, which have been based mainly on gross differences in floral size and various morphological autapomorphies. Based on our current sampling, Campylocentrum includes both leafy and leafless species and is sister to a broadly defined Dendrophylax

COMPTEL upper limits for Seyfert galaxies

The gamma‐ray emission of Seyfert galaxies has fallen far short of pre‐GRO expectations. No single object of this class has been detected by either COMPTEL or EGRET, and OSSE has detected only a fraction of the Seyferts expected. To derive a more stringent upper limit to the emission from these objects in the energy ranges 0.75 to 1 and 1 to 3 MeV, we have summed a large number of COMPTEL observations acquired during Phase 1 of the GRO mission. From a total of 47 observations of 23 individual X‐ray selected Seyfert galaxies, we derive preliminary upper limits of 8×10−8 photons/(cm2 s keV) in the 0.75‐1 MeV band and 1×10−8 photons/(cm2 s keV) in the 1‐3 MeV band