Structure of neodymium sulfate octahydrate

The problems of X-ray crystal structure determination require some type of automatic computing machinery. An evaluation of these problems has lead to the conclusions that a parallel channel relay digital computer operating in conjunction with the standard I. B. M. units will meet the calculation needs of a structure determination and greatly shorten the time and labor involved. A brief description of a relay computer designed to meet these needs has been given. The computer will be able to perform all of the calculations required with the exception of the Patterson and electron density calculations. The latter may be carried out efficiently on standard I. B. M. units

Crystal structure and magnetic properties of LiCuCl3-2H2O

Interest in the study of the effect of cation size upon the configuration assumed by a complex anion led to the determination of the crystal structure of LiCuCl3 • 2H2O. A unique (Cu2Cl6)= dimer ion was discovered in the structure that was determined by conventional X-ray diffraction techniques. These dimer ions are linked together into a zigzag chain by means of long Cu-Cl bonds between the dimers. The chains in any given unit cell of the crystal are related to each other by a two-fold screw axis. Each dimer has two water molecules associated with it through long Cu-O interactions, giving a distorted octahedral array about each copper ion. There are two additional water molecules per dimer ion which are lattice waters and which, along with one of the other oxygens and a chlorine ion, form a tetrahedral hole in which the lithium ion is probably located

Nonlinear Network Dynamics on Earthquake Fault Systems

Earthquake faults occur in networks that have dynamical modes not displayed by single isolated faults. Using simulations of the network of strike-slip faults in southern California, we find that the physics depends critically on both the interactions among the faults, which are determined by the geometry of the fault network, as well as on the stress dissipation properties of the nonlinear frictional physics, similar to the dynamics of integrate-and-fire neural networks.Comment: 12 pages, 4 figure

Gutenberg Richter and Characteristic Earthquake Behavior in Simple Mean-Field Models of Heterogeneous Faults

The statistics of earthquakes in a heterogeneous fault zone is studied analytically and numerically in the mean field version of a model for a segmented fault system in a three-dimensional elastic solid. The studies focus on the interplay between the roles of disorder, dynamical effects, and driving mechanisms. A two-parameter phase diagram is found, spanned by the amplitude of dynamical weakening (or ``overshoot'') effects (epsilon) and the normal distance (L) of the driving forces from the fault. In general, small epsilon and small L are found to produce Gutenberg-Richter type power law statistics with an exponential cutoff, while large epsilon and large L lead to a distribution of small events combined with characteristic system-size events. In a certain parameter regime the behavior is bistable, with transitions back and forth from one phase to the other on time scales determined by the fault size and other model parameters. The implications for realistic earthquake statistics are discussed.Comment: 21 pages, RevTex, 6 figures (ps, eps

Self-organized criticality and synchronization in a lattice model of integrate-and-fire oscillators

We introduce two coupled map lattice models with nonconservative interactions and a continuous nonlinear driving. Depending on both the degree of conservation and the convexity of the driving we find different behaviors, ranging from self-organized criticality, in the sense that the distribution of events (avalanches) obeys a power law, to a macroscopic synchronization of the population of oscillators, with avalanches of the size of the system.Comment: 4 pages, Revtex 3.0, 3 PostScript figures available upon request to [email protected]

Progression of C-reactive protein from birth through preadolescence varies by mode of delivery

INTRODUCTION: Delivery via caesarean section (C-section) has been associated with an increased risk of childhood chronic diseases such as obesity and asthma, which may be due to underlying systemic inflammation. However, the impact of specific C-section types may be differential, as emergency C-sections typically involve partial labor and/or membrane rupture. Our objectives were to determine if mode of delivery associates with longitudinal profiles of high sensitivity CRP (hs-CRP) -a marker of systemic inflammation-from birth through preadolescence, and to examine if CRP mediates the association between mode of delivery and preadolescent body mass index (BMI). METHODS: Data from the WHEALS birth cohort (N = 1,258) were analyzed; 564 of the 1,258 children in the cohort had data available for analysis. Longitudinal plasma samples (birth through 10-years of age) from 564 children from were assayed for hs-CRP levels. Maternal medical records were abstracted to obtain mode of delivery. Growth mixture models (GMMs) were used to determine classes of hs-CRP trajectories. Poisson regression with robust error variance was used to calculate risk ratios (RRs). RESULTS: Two hs-CRP trajectory classes were identified: class 1 (76% of children) was characterized by low hs-CRP, while class 2 (24% of children) was characterized by high and steadily increasing hs-CRP. In multivariable models, children delivered via planned C-section had 1.15 times higher risk of being in hs-CRP class 2, compared to vaginal deliveries (p = 0.028), while no association was found for unplanned C-section deliveries [RR (95% CI) = 0.96 (0.84, 1.09); p = 0.49]. Further, the effect of planned C-section on BMI z-score at age 10 was significantly mediated by hs-CRP class (percent mediated = 43.4%). CONCLUSIONS: These findings suggest potentially beneficial effects of experiencing partial or full labor, leading to a lower trajectory of systemic inflammation throughout childhood and decreased BMI during preadolescence. These findings may have implications for chronic disease development later in life

(Micro)evolutionary changes and the evolutionary potential of bird migration

Seasonal migration is the yearly long-distance movement of individuals between their breeding and wintering grounds. Individuals from nearly every animal group exhibit this behavior, but probably the most iconic migration is carried out by birds, from the classic V-shape formation of geese on migration to the amazing nonstop long-distance flights undertaken by Arctic Terns Sterna paradisaea. In this chapter, we discuss how seasonal migration has shaped the field of evolution. First, this behavior is known to turn on and off quite rapidly, but controversy remains concerning where this behavior first evolved geographically and whether the ancestral state was sedentary or migratory (Fig. 7.1d, e). We review recent work using new analytical techniques to provide insight into this topic. Second, it is widely accepted that there is a large genetic basis to this trait, especially in groups like songbirds that migrate alone and at night precluding any opportunity for learning. Key hypotheses on this topic include shared genetic variation used by different populations to migrate and only few genes being involved in its control. We summarize recent work using new techniques for both phenotype and genotype characterization to evaluate and challenge these hypotheses. Finally, one topic that has received less attention is the role these differences in migratory phenotype could play in the process of speciation. Specifically, many populations breed next to one another but take drastically different routes on migration (Fig. 7.2). This difference could play an important role in reducing gene flow between populations, but our inability to track most birds on migration has so far precluded evaluations of this hypothesis. The advent of new tracking techniques means we can track many more birds with increasing accuracy on migration, and this work has provided important insight into migration's role in speciation that we will review here

PAH–DNA Adducts, Cigarette Smoking, GST Polymorphisms, and Breast Cancer Risk

BackgroundPolycyclic aromatic hydrocarbons (PAHs) may increase breast cancer risk, and the association may be modified by inherited differences in deactivation of PAH intermediates by glutathione S-transferases (GSTs). Few breast cancer studies have investigated the joint effects of multiple GSTs and a PAH biomarker.ObjectiveWe estimated the breast cancer risk associated with multiple polymorphisms in the GST gene (GSTA1, GSTM1, GSTP1, and GSTT1) and the interaction with PAH–DNA adducts and cigarette smoking.MethodsWe conducted unconditional logistic regression using data from a population-based sample of women (cases/controls, respectively): GST polymorphisms were genotyped using polymerase chain reaction and matrix-assisted laser desorption/ionization time-of-flight assays (n = 926 of 916), PAH–DNA adduct blood levels were measured by competitive enzyme-linked immunosorbent assay (n = 873 of 941), and smoking status was assessed by in-person questionnaires (n = 943 of 973).ResultsOdds ratios for joint effects on breast cancer risk among women with at least three variant alleles were 1.56 [95% confidence interval (CI), 1.13–2.16] for detectable PAH–DNA adducts and 0.93 (95% CI, 0.56–1.56) for no detectable adducts; corresponding odds ratios for three or more variants were 1.18 (95% CI, 0.82–1.69) for ever smokers and 1.44 (95% CI, 0.97–2.14) for never smokers. Neither interaction was statistically significant (p = 0.43 and 0.62, respectively).ConclusionWe found little statistical evidence that PAHs interacted with GSTT1, GSTM1, GSTP1, and GSTA1 polymorphisms to further increase breast cancer risk

Field Studies Reveal Strong Postmating Isolation between Ecologically Divergent Butterfly Populations

A mismatch between hybrid butterflies and their ecological environment restricts gene flow between populations that feed on different host plants, highlighting the potential importance of a seldom-studied mechanism of reproductive isolation

Recruitment using mobile telephones in an Irish general population sexual health survey: challenges and practical solutions

BACKGROUND: Non-coverage of households without a landline telephone is a major concern of telephone survey researchers. Sampling mobile telephone users in national surveys is vital in order to gain access to the growing proportion of households that use mobile telephones extensively or exclusively. The complex logistics of conducting surveys with mobile telephones have been discussed in the literature. This paper outlines the actual challenges encountered during a recent national sexual health survey in Ireland, which utilized a mobile telephone sampling frame to recruit approximately half of the sample. METHOD: The 2010 Irish Contraception and Crisis Pregnancy Survey (ICCP-2010) is a nationally representative sample of adults aged 18-45 years living in Ireland (n = 3002; 1416 recruited by landline telephone and 1586 recruited by mobile telephone). The overall response rate for the survey was 69% (79% for the landline telephone strand; 61% for the mobile telephone strand). All interviews were conducted using computer-assisting telephone interviewing. RESULTS: During the 18-week fieldwork period, five main challenges relating to the use of mobile telephones were encountered: (1) explaining to respondents how random digit dialling works in relation to mobile telephones; (2) establishing the respondent\u27s eligibility; (3) calling the respondent with the Caller ID blocked or withheld; (4) calling the respondent when they are in any number of locations or situations; and (5) explaining to respondents the importance of refusal conversion calls for the response rate calculation. Details of how the survey protocols and procedures were monitored and adapted throughout the study to ensure a high response rate are outlined. CONCLUSION: It is undeniably more challenging to recruit respondents using mobile telephones as opposed to landline telephones. Respondents are generally not familiar with being contacted on their personal mobile telephone for the purposes of being recruited for a research study. The main challenge for survey methodologists and interviewers is to devise simple protocols to explain to respondents why they are being contacted on a mobile telephone. Recommendations for survey researchers interested in using this methodological approach in the future are discussed