Distances on a one-dimensional lattice from noncommutative geometry

In the following paper we continue the work of Bimonte-Lizzi-Sparano on distances on a one dimensional lattice. We succeed in proving analytically the exact formulae for such distances. We find that the distance to an even point on the lattice is the geometrical average of the ``predecessor'' and ``successor'' distances to the neighbouring odd points.Comment: LaTeX file, few minor typos corrected, 9 page

Disease variants in genomes of 44 centenarians

To identify previously reported disease mutations that are compatible with extraordinary longevity, we screened the coding regions of the genomes of 44 Ashkenazi Jewish centenarians. Individual genome sequences were generated with 30x coverage on the Illumina HiSeq 2000 and single-nucleotide variants were called with the genome analysis toolkit (GATK). We identified 130 coding variants that were annotated as pathogenic or likely pathogenic based on the ClinVar database and that are infrequent in the general population. These variants were previously reported to cause a wide range of degenerative, neoplastic, and cardiac diseases with autosomal dominant, autosomal recessive, and X-linked inheritance. Several of these variants are located in genes that harbor actionable incidental findings, according to the recommendations of the American College of Medical Genetics. In addition, we found risk variants for late-onset neurodegenerative diseases, such as the APOE epsilon4 allele that was even present in a homozygous state in one centenarian who did not develop Alzheimer\u27s disease. Our data demonstrate that the incidental finding of certain reported disease variants in an individual genome may not preclude an extraordinarily long life. When the observed variants are encountered in the context of clinical sequencing, it is thus important to exercise caution in justifying clinical decisions

Dirac Operators and the Calculation of the Connes Metric on arbitrary (Infinite) Graphs

As an outgrowth of our investigation of non-regular spaces within the context of quantum gravity and non-commutative geometry, we develop a graph Hilbert space framework on arbitrary (infinite) graphs and use it to study spectral properties of graph-Laplacians and graph-Dirac-operators. We define a spectral triplet sharing most of the properties of what Connes calls a spectral triple. With the help of this scheme we derive an explicit expression for the Connes-distance function on general directed or undirected graphs. We derive a series of apriori estimates and calculate it for a variety of examples of graphs. As a possibly interesting aside, we show that the natural setting of approaching such problems may be the framework of (non-)linear programming or optimization. We compare our results (arrived at within our particular framework) with the results of other authors and show that the seeming differences depend on the use of different graph-geometries and/or Dirac operators.Comment: 27 pages, Latex, comlementary to an earlier paper, general treatment of directed and undirected graphs, in section 4 a series of general results and estimates concerning the Connes Distance on graphs together with examples and numerical estimate

Effects of proton irradiation on the microstructure and microchemistry of type 304L stainless steel

A research program has been undertaken to determine the origins of irradiation-assisted stress corrosion cracking (IASCC) in austenitic alloys in light water reactors, and the effect of impurities on IASCC susceptibility. Controlled purity alloys of 304L stainless steel were irradiated with protons at 400[deg]C to a dose of 1 dpa and analyzed via Auger electron spectroscopy (AES) and scanning transmission electron microscopy (STEM). The alloys investigated were an ultra-high purity (UHP) alloy and UHP alloys containing phosphorus (UHP + P), sulfur (UHP + S), or silicon (UHP + Si). Microstructural and microchemical changes were quantified and compared with literature results for other irradiating species. Following irradiation, the alloys showed dislocation loop formation and growth, "black dot" loops, and a change in the nature of the dislocation network. AES and STEM microchemical analysis of the alloys revealed Cr depletion of up to 6 at% and Ni enrichment of up to 6.6 at% at the grain boundaries of the alloys, with more segregation observed in the alloys containing impurities than in the UHP alloy. Significant grain boundary enrichment of P and Si in the UHP + P and UHP + Si alloys, respectively, was also observed. The results of the analyses of proton-irradiated samples are shown to compare favorably with previous studies on samples irradiated with neutrons at or near LWR conditions.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/30554/1/0000187.pd

Quantitative analysis of radiation-induced grain-boundary segregation measurements

Radiation-induced and precipitation-induced grain-boundary segregation profiles are routinely measured by scanning-transmission electron microscopy using energy-dispersive X-ray spectroscopy (STEM-EDS). However, radiation-induced grain-boundary segregation (RIS) profiles achieved at low and moderate temperatures are exceedingly narrow, typically less than 10 nm full width at half maximum. Since the instrumental spatial resolution can be a significant fraction of this value, the determination of grain boundary compositions poses a formidable challenge. STEM-EDS and Auger electron spectroscopy (AES) measurements are reported, performed on controlled-purity alloys of type 304L stainless steel irradiated with 3.4 MeV protons to 1 displacement per atom at 400[deg]C. Because of statistical noise and the practical lower limit on the step size in STEM, deconvolution of the measured data does not yield physical results. An alternative analysis of STEM data is presented. Numerical calculations of RIS profiles are convoluted with the instrumental broadening function and modified iteratively to fit the data, yielding a "best estimate" profile. This "best estimate" is convoluted with the Auger intensity profile to yield a simulated AES measurement, which is compared with the actual AES measurement to provide an independent test of the validity of the "best estimate". For impurities with a narrow segregation profile and an Auger electron escape depth of one monolayer, a combination of STEM and AES data allows a determination of the width of the segregated layer. It is found that, in an ultrahigh-purity alloy doped with P, the latter is essentially contained in a single monolayer.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/31453/1/0000374.pd

Ashkenazi Jewish Centenarians Do Not Demonstrate Enrichment in Mitochondrial Haplogroup J

BACKGROUND: Association of mitochondrial haplogroup J with longevity has been reported in several population subgroups. While studies from northern Italy and Finland, have described a higher frequency of haplogroup J among centenarians in comparison to non-centenarian, several other studies could not replicate these results and suggested various explanations for the discrepancy. METHODOLOGY/PRINCIPAL FINDINGS: We have evaluated haplogroup frequencies among Ashkenazi Jewish centenarians using two different sets of matched controls. No difference was observed in the haplogroup J frequencies between the centenarians or either matched control group, despite adequate statistical power to detect such a difference. Furthermore, the lack of association was robust to population substructure in the Ashkenazi Jewish population. Given this discrepancy with the previous reported associations in the northern Italian and the Finnish populations, we conducted re-analysis of these previously published data, which supported one of several possible explanations: i) inadequate matching of cases and controls; ii) inadequate adjustment for multiple comparison testing; iii) cryptic population stratification. CONCLUSIONS/SIGNIFICANCE: There does not exist a universal association of mitochondrial haplogroup J with longevity across all population groups. Reported associations in specialized populations may reflect genetic or other interactions specific to those populations or else cryptic confounding influences, such as inadequate matching attributable to population substructure, which are of general relevance to all studies of the possible association of mitochondrial DNA haplogroups with common complex phenotypes

Lipoprotein Genotype and Conserved Pathway for Exceptional Longevity in Humans

Alteration of single genes involved in nutrient and lipoprotein metabolism increases longevity in several animal models. Because exceptional longevity in humans is familial, it is likely that polymorphisms in genes favorably influence certain phenotypes and increase the likelihood of exceptional longevity. A group of Ashkenazi Jewish centenarians ( n = 213), their offspring ( n = 216), and an age-matched Ashkenazi control group ( n = 258) were genotyped for 66 polymorphisms in 36 candidate genes related to cardiovascular disease (CVD). These genes were tested for association with serum lipoprotein levels and particle sizes, apolipoprotein A1, B, and C-3 levels and with outcomes of hypertension, insulin resistance, and mortality. The prevalence of homozygosity for the −641C allele in the APOC3 promoter (rs2542052) was higher in centenarians (25%) and their offspring (20%) than in controls (10%) ( p = 0.0001 and p = 0.001, respectively). This genotype was associated with significantly lower serum levels of APOC3 and a favorable pattern of lipoprotein levels and sizes. We found a lower prevalence of hypertension and greater insulin sensitivity in the −641C homozygotes, suggesting a protective effect against CVD and the metabolic syndrome. Finally, in a prospectively studied cohort, a significant survival advantage was demonstrated in those with the favorable −641C homozygote ( p < 0.0001). Homozygosity for the APOC3 −641C allele is associated with a favorable lipoprotein profile, cardiovascular health, insulin sensitivity, and longevity. Because modulation of lipoproteins is also seen in genetically altered longevity models, it may be a common pathway influencing lifespan from nematodes to humans

Epitaxial growth in dislocation-free strained alloy films: Morphological and compositional instabilities

The mechanisms of stability or instability in the strained alloy film growth are of intense current interest to both theorists and experimentalists. We consider dislocation-free, coherent, growing alloy films which could exhibit a morphological instability without nucleation. We investigate such strained films by developing a nonequilibrium, continuum model and by performing a linear stability analysis. The couplings of film-substrate misfit strain, compositional stress, deposition rate, and growth temperature determine the stability of film morphology as well as the surface spinodal decomposition. We consider some realistic factors of epitaxial growth, in particular the composition dependence of elastic moduli and the coupling between top surface and underlying bulk of the film. The interplay of these factors leads to new stability results. In addition to the stability diagrams both above and below the coherent spinodal temperature, we also calculate the kinetic critical thickness for the onset of instability as well as its scaling behavior with respect to misfit strain and deposition rate. We apply our results to some real growth systems and discuss the implications related to some recent experimental observations.Comment: 26 pages, 13 eps figure