Global patterns of STR sequence variation: Sequencing the CEPH human genome diversity panel for 58 forensic STRs using the Illumina ForenSeq DNA Signature Prep Kit.

The 944 individuals of the CEPH human genome diversity panel (HGDP-CEPH), a standard sample set of 51 globally distributed populations, were sequenced using the Illumina ForenSeq™ DNA Signature Prep Kit. The ForenSeq™ system is a single multiplex for the MiSeq/FGx™ massively parallel sequencing instrument, comprising: amelogenin, 27 autosomal STRs, 24 Y-STRs, 7 X-STRs, and 94 SNPforID+Kiddlab autosomal ID-SNPs (plus optionally detected ancestry and phenotyping SNP sets). We report in detail the patterns of sequence variation observed in the repeat regions of the 58 forensic STR loci typed by the ForenSeq™ system. Sequence alleles were characterized and repeat region structures annotated by aligning the ForenSeq™ sequence output to the latest GRCh38 human reference sequence, necessitating the reversal and re-alignment of STR allele sequences reported by the Forenseq™ system in 20 of 58 STRs (plus the reverse alleles in two Y-STRs with duplicated-inverted repeat regions). Individual population sample sizes of the HGDP-CEPH panel do not allow reliable inferences to be made about levels of genetic variability in low frequency STR alleles-where particular sequence variants are found in only a few individuals; but we assessed the occurrence of both population-specific sequence variants and singleton observations; finding each of these in a sizeable proportion of HGDP-CEPH samples, with consequences for planning the co-ordinated compilation of sequence variation on a much larger scale than was required before by forensic laboratories now adopting massively parallel sequencing.

Characterization of the photocurrents generated by the laser of atomic force microscopes.

The conductive atomic force microscope (CAFM) has become an essential tool for the nanoscale electronic characterization of many materials and devices. When studying photoactive samples, the laser used by the CAFM to detect the deflection of the cantilever can generate photocurrents that perturb the current signals collected, leading to unreliable characterization. In metal-coated semiconductor samples, this problem is further aggravated, and large currents above the nanometer range can be observed even without the application of any bias. Here we present the first characterization of the photocurrents introduced by the laser of the CAFM, and we quantify the amount of light arriving to the surface of the sample. The mechanisms for current collection when placing the CAFM tip on metal-coated photoactive samples are also analyzed in-depth. Finally, we successfully avoided the laser-induced perturbations using a two pass technique: the first scan collects the topography (laser ON) and the second collects the current (laser OFF). We also demonstrate that CAFMs without a laser (using a tuning fork for detecting the deflection of the tip) do not have this problem.

Design, methods and demographic findings of the DEMINVALL survey: a population-based study of Dementia in Valladolid, Northwestern Spain.

BACKGROUND: This article describes the rationale and design of a population-based survey of dementia in Valladolid (northwestern Spain). The main aim of the study was to assess the epidemiology of dementia and its subtypes. Prevalence of anosognosia in dementia patients, nutritional status, diet characteristics, and determinants of non-diagnosed dementia in the community were studied. The main sociodemographic, educational, and general health status characteristics of the study population are described. METHODS: Cross-over and cohort, population-based study. A two-phase door-to-door study was performed. Both urban and rural environments were included. In phase 1 (February 2009 - February 2010) 28 trained physicians examined a population of 2,989 subjects (age: ≥ 65 years). The seven-minute screen neurocognitive battery was used. In phase 2 (May 2009 - May 2010) 4 neurologists, 1 geriatrician, and 3 neuropsychologists confirmed the diagnosis of dementia and subtype in patients screened positive by a structured neurological evaluation. Specific instruments to assess anosognosia, the nutritional status and diet characteristics were used. Of the initial sample, 2,170 subjects were evaluated (57% female, mean age 76.5 ± 7.8, 5.2% institutionalized), whose characteristics are described. 227 persons were excluded for various reasons. Among those eligible were 592 non-responders. The attrition bias of non-responders was lower in rural areas. 241 screened positive (11.1%). DISCUSSION: The survey will explore some clinical, social and health related life-style variables of dementia. The population size and the diversification of social and educational backgrounds will contribute to a better knowledge of dementia in our environment.

Polycrystallization effects on the nanoscale electrical properties of high-k dielectrics.

In this study, atomic force microscopy-related techniques have been used to investigate, at the nanoscale, how the polycrystallization of an Al2O3-based gate stack, after a thermal annealing process, affects the variability of its electrical properties. The impact of an electrical stress on the electrical conduction and the charge trapping of amorphous and polycrystalline Al2O3 layers have been also analyzed.