72 research outputs found
A Postscript to a Paper of A. Baker
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/135153/1/blms0075.pd
Classification of one-dimensional quasilattices into mutual local-derivability classes
One-dimensional quasilattices are classified into mutual local-derivability
(MLD) classes on the basis of geometrical and number-theoretical
considerations. Most quasilattices are ternary, and there exist an infinite
number of MLD classes. Every MLD class has a finite number of quasilattices
with inflation symmetries. We can choose one of them as the representative of
the MLD class, and other members are given as decorations of the
representative. Several MLD classes of particular importance are listed. The
symmetry-preserving decorations rules are investigated extensively.Comment: 42 pages, latex, 5 eps figures, Published in JPS
Diffractive point sets with entropy
After a brief historical survey, the paper introduces the notion of entropic
model sets (cut and project sets), and, more generally, the notion of
diffractive point sets with entropy. Such sets may be thought of as
generalizations of lattice gases. We show that taking the site occupation of a
model set stochastically results, with probabilistic certainty, in well-defined
diffractive properties augmented by a constant diffuse background. We discuss
both the case of independent, but identically distributed (i.i.d.) random
variables and that of independent, but different (i.e., site dependent) random
variables. Several examples are shown.Comment: 25 pages; dedicated to Hans-Ude Nissen on the occasion of his 65th
birthday; final version, some minor addition
Seasonal changes in a sandy beach fish assemblage at Canto Grande, Santa Catarina, South Brazil
Copyright © 2004 Coastal Education and Research Foundation (CERF).Neste trabalho realizaramse amostragens, com uma rede de praia, de modo a estudar a comunidade de peixes de substrato arenoso na enseada de Canto Grande, Santa Catarina, Brasil. As amostragens realizaramse em intervalos de 3 horas durante perĂodos de 24 h, numa base bimensal, entre Abril de 1996 e Fevereiro de 1997. Verificouse existir uma variação sazonal no nĂșmero de espĂ©cies, densidade de peixes e biomassa, tendo os valores mais elevados ocorrido em Fevereiro (38 espĂ©cies, 257.6 peixes 1000 mËÂČ, 2286.4 g 1000 mËÂČ). Recolheuse um total de 67 espĂ©cies, pertencentes a 56 gĂ©neros e a 33 famĂlias, sendo a comunidade dominada por sete espĂ©cies pertencentes a trĂȘs famĂlias: Atherinella brasiliensis (Atherinidae); Brevoortia pectinata, Harengula clupeola e Sardinella brasiliensis (Clupeidae); Anchoviella lepidontostole, Cetengraulis edentulus e Lycengraulis grossidens (Engraulidae). Tanto a diversidade de espĂ©cies (HâČ) como a equitabilidade (JâČ) foram mĂ©dias a elevadas ao longo do ano devido Ă baixa dominĂąncia. A maior mudança na estrutura da comunidade ocorreu entre os meses de Inverno (Julho e Agosto) e as outras estaçÔes. Nenhuma das espĂ©cies dominantes pode ser classificada como residente. Os principais predadores foram Pomatomus saltator (Inverno) e Trichiurus lepturus (VerĂŁo). A maior parte das espĂ©cies observadas foram ou peixes juvenis ou espĂ©cies pelĂĄgicas de pequeno tamanho e fortemente gregĂĄrias.ABSTRACT: A shallow-water fish assemblage, over a soft, sandy bottom, at Canto Grande, Santa Catarina, Brazil, was sampled with a beach seine. Sampling was undertaken at 3 h intervals over 24 h on a bimonthly basis between April 1996 and February 1997. There was a seasonal variation in the number of species, density of fishes and biomass with the highest values in February (38 species, 257.6 fish 1000 mËÂČ, 2286.4 g 1000 mËÂČ). A total of 67 species, belonging to 56 genera and 33 families were collected and the assemblage was dominated by seven species belonging to three families: Atherinella brasiliensis (Atherinidae); Brevoortia pectinata, Harengula clupeola and Sardinella brasiliensis (Clupeidae); Anchoviella lepidontostole, Cetengraulis edentulus and Lycengraulis grossidens (Engraulidae). Species diversity (HâČ) and equitability (JâČ) were medium to high throughout the year due to the low dominance. The largest change in the assemblage structure occurred between winter months (July and August) and the other seasons. None of the dominant species can be classified as a resident. Main predators were Pomatomus saltator (winter) and Trichiurus lepturus (summer). Most of the species observed were either juvenile fish or small pelagic and strongly gregarious species
Longitudinal analyses of the DNA methylome in deployed military servicemen identify susceptibility loci for post-traumatic stress disorder
In order to determine the impact of the epigenetic response to traumatic stress on post-traumatic stress disorder (PTSD), this study examined longitudinal changes of genome-wide blood DNA methylation profiles in relation to the development of PTSD symptoms in two prospective military cohorts (one discovery and one replication data set). In the first cohort consisting of male Dutch military servicemen (n=93), the emergence of PTSD symptoms over a deployment period to a combat zone was significantly associated with alterations in DNA methylation levels at 17 genomic positions and 12 genomic regions. Evidence for mediation of the relation between combat trauma and PTSD symptoms by longitudinal changes in DNA methylation was observed at several positions and regions. Bioinformatic analyses of the reported associations identified significant enrichment in several pathways relevant for symptoms of PTSD. Targeted analyses of the significant findings from the discovery sample in an independent prospective cohort of male US marines (n=98) replicated the observed relation between decreases in DNA methylation levels and PTSD symptoms at genomic regions in ZFP57, RNF39 and HIST1H2APS2. Together, our study pinpoints three novel genomic regions where longitudinal decreases in DNA methylation across the period of exposure to combat trauma marks susceptibility for PTSD
Meta-analysis of genome-wide DNA methylation identifies shared associations across neurodegenerative disorders
Background
People with neurodegenerative disorders show diverse clinical syndromes, genetic heterogeneity, and distinct brain pathological changes, but studies report overlap between these features. DNA methylation (DNAm) provides a way to explore this overlap and heterogeneity as it is determined by the combined effects of genetic variation and the environment. In this study, we aim to identify shared blood DNAm differences between controls and people with Alzheimerâs disease, amyotrophic lateral sclerosis, and Parkinsonâs disease.
Results
We use a mixed-linear model method (MOMENT) that accounts for the effect of (un)known confounders, to test for the association of each DNAm site with each disorder. While only three probes are found to be genome-wide significant in each MOMENT association analysis of amyotrophic lateral sclerosis and Parkinsonâs disease (and none with Alzheimerâs disease), a fixed-effects meta-analysis of the three disorders results in 12 genome-wide significant differentially methylated positions. Predicted immune cell-type proportions are disrupted across all neurodegenerative disorders. Protein inflammatory markers are correlated with profile sum-scores derived from disease-associated immune cell-type proportions in a healthy aging cohort. In contrast, they are not correlated with MOMENT DNAm-derived profile sum-scores, calculated using effect sizes of the 12 differentially methylated positions as weights.
Conclusions
We identify shared differentially methylated positions in whole blood between neurodegenerative disorders that point to shared pathogenic mechanisms. These shared differentially methylated positions may reflect causes or consequences of disease, but they are unlikely to reflect cell-type proportion differences
Article 01.1.1 The Number-Wall Algorithm: an LFSR Cookbook
This paper might fairly be said to fall between three stools: the presentation and justification of a number of related computational methods associated with LFSR sequences, including finding the order, recurrence and general term; the exploration of tutorial examples and survey of applications; and a rigorous treatment of one topic, the recursive construction of the number wall, which we believe has not previously appeared. The Number Wall is the table of Toeplitz determinants associated with a sequence over an arbitrary integral domain, particularly Z, Fp, R, and their polynomial and series extensions by many variables. The relation borne by number walls to LFSR (linear recurring shift register) sequences is analogous to that borne by difference tables to polynomial sequences: They can be employed to find the order and recurrence §3, or to compute further terms and express the general term explicitly §10 (although other more elaborate methods may be more efficient §12, §8). Much of the paper collects and summarizes relevant classical theory in Formal Power Series §1, Linear Recurrences §2, PadĂ© Blocks (essentially) §3, Vandermonde Interpolation §8, and Difference Tables §9. A âframe â relation between the elements of the number wall containing zeros (a non-normal C-table, in PadĂ© terminology) is stated and proved §4, with the resulting recursive generation algorithm and some special cases §5; the consequences of basing the wall on this algorithm instead are explored §6, and a cellular automato
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