Finite strain in Elastic problems

This article does not have an abstract

Surface Phonons and Other Localized Excitations

The diatomic linear chain of masses coupled by harmonic springs is a textboook model for vibrational normal modes (phonons) in crystals. In addition to propagating acoustic and optic branches, this model is known to support a ``gap mode'' localized at the surface, provided the atom at the surface has light rather than heavy mass. An elementary argument is given which explains this mode and provides values for the frequency and localization length. By reinterpreting this mode in different ways, we obtain the frequency and localization lengths for three other interesting modes: (1) the surface vibrational mode of a light mass impurity at the surface of a monatomic chain; (2) the localized vibrational mode of a stacking fault in a diatomic chain; and (3) the localized vibrational mode of a light mass impurity in a monatomic chain.Comment: 5 pages with 4 embedded postscript figures. This paper will appear in the American Journal of Physic

The Implicit Price of Urban Public Parks and Greenways: A Spatial-Contextual Approach

This is an Author's Original Manuscript of an article submitted for consideration in the Journal of Environmental Planning and Management [copyright Taylor & Francis]; Journal of Environmental Planning and Management is available online at http://www.tandfonline.com/This paper examines the value residents place on public parks in a mid-sized urban area. The analysis makes a direct contribution to the literature by examining the extent to which spatial and neighborhood context is related to the house price premium or discount associated with public recreational opportunities, natural resource areas, and urban greenways. The analysis shows that the value of public parks and greenways varies across space, neighborhood context, and park type. Community area fixed-effects are included to bolster the findings. The findings indicate that park and greenway investment should be planned and managed contextually in urban areas. Park planners can use these findings to inform public policy debates over park investment and, perhaps, support efforts focused on comprehensive neighborhood planning

Finite strain in Elastic problems. II

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Causal connectivity of evolved neural networks during behavior

To show how causal interactions in neural dynamics are modulated by behavior, it is valuable to analyze these interactions without perturbing or lesioning the neural mechanism. This paper proposes a method, based on a graph-theoretic extension of vector autoregressive modeling and 'Granger causality,' for characterizing causal interactions generated within intact neural mechanisms. This method, called 'causal connectivity analysis' is illustrated via model neural networks optimized for controlling target fixation in a simulated head-eye system, in which the structure of the environment can be experimentally varied. Causal connectivity analysis of this model yields novel insights into neural mechanisms underlying sensorimotor coordination. In contrast to networks supporting comparatively simple behavior, networks supporting rich adaptive behavior show a higher density of causal interactions, as well as a stronger causal flow from sensory inputs to motor outputs. They also show different arrangements of 'causal sources' and 'causal sinks': nodes that differentially affect, or are affected by, the remainder of the network. Finally, analysis of causal connectivity can predict the functional consequences of network lesions. These results suggest that causal connectivity analysis may have useful applications in the analysis of neural dynamics

Cloning, sequencing, and characterization of the hexahydro-1,3,5-trinitro-1,3,5-triazine degradation gene cluster from Rhodococcus rhodochrous

Hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) is a high explosive which presents an environmental hazard as a major land and groundwater contaminant. Rhodococcus rhodochrous strain 11Y was isolated from explosive contaminated land and is capable of degrading RDX when provided as the sole source of nitrogen for growth. Products of RDX degradation in resting-cell incubations were analyzed and found to include nitrite, formaldehyde, and formate. No ammonium was excreted into the medium, and no dead-end metabolites were observed. The gene responsible for the degradation of RDX in strain 11Y is a constitutively expressed cytochrome P450-like gene, xpLA, which is found in a gene cluster with an adrenodoxin reductase homologue, xplB. The cytochrome P450 also has a flavodoxin domain at the N terminus. This study is the first to present a gene which has been identified as being responsible for RDX biodegradation. The mechanism of action of XplA on RDX is thought to involve initial denitration followed by spontaneous ring cleavage and mineralization

All-cause and liver-related mortality risk factors in excessive drinkers: Analysis of data from the UK biobank

BACKGROUND High alcohol intake is associated with increased mortality. We aimed to identify factors affecting mortality in people drinking extreme amounts of alcohol. METHODS We obtained information from the UK Biobank on approximately 500,000 participants aged 40-70 years at baseline assessment in 2006-2010. Habitual alcohol intake, lifestyle and physiological data, laboratory test results, and hospital diagnoses and death certificate data (to June 2020) for 5136 men (2.20% of male participants) and 1504 women (0.60%) who reported consuming ≥80 or ≥50 g/day, respectively, were used in survival analysis. RESULTS Mortality hazard ratios for these excessive drinkers, compared to all other participants, were 2.02 (95% CI 1.89-2.17) for all causes, 1.89 (1.69-2.12) for any cancer, 1.87 (1.61-2.17) for any circulatory disease, and 9.40 (7.00-12.64) for any liver disease. Liver disease diagnosis or abnormal liver function tests predicted not only deaths attributed to liver disease but also those from cancers or circulatory diseases. Mortality among excessive drinkers was also associated with quantitative alcohol intake; diagnosed alcohol dependence, harmful use, or withdrawal syndrome; and current smoking at assessment. CONCLUSIONS People with chronic excessive alcohol intake experience decreased average survival, but there is substantial variation in their mortality, with liver abnormality and alcohol dependence or other alcohol use disorders associated with a worse prognosis. Clinically, patients with these risk factors and high alcohol intake should be considered for early or intensive management. Research can usefully focus on the factors predisposing to dependence or liver abnormality

Intra and Inter-Neighborhood Income Inequality and Crime

Author's manuscript made available in accordance with the publisher's policy.One important factor in many macro-level theories of crime is income inequality. Although research generally shows that low levels of neighborhood income are associated with crime, research studies have been less clear on whether income inequality is a robust, independent predictor of crime, particularly in small area studies, and few studies have explicitly considered income inequality between neighborhoods, and those that do typically focus on homicide. The current study examines whether within and between neighborhood income inequality is associated with variation in violent and property crime. We employ geocoded Uniform Crime Report data from the Indianapolis police department and economic and demographic characteristics of the population from the American Community Survey for 2005–2009. Consistent with prior research, lower levels of income were associated with higher violent and property crime counts. Within-tract income inequality was also associated with higher Uniform Crime Reports violent and property crimes in most models. Results also showed that the ratio of tract income levels to neighboring tracts is associated with variation in crime. Thus, both local and nearby income inequality affect crime. Implications for theory and policy are discussed

The Effect of Foreclosures on Crime in Indianapolis, 2003-2008

Author's manuscript made available in accordance with the publisher's policy.Objective Until recently, few studies have examined the relationship between home foreclosures and crime. Foreclosures are one major source of neighborhood instability and can be expected to affect crime from several theoretical perspectives. Some recent research has found conflicting results on whether foreclosures cause crime. Method This study examines whether foreclosures are a robust predictor of crime and whether the effect of foreclosures on crime varies across neighborhood contexts. We estimate fixed-effects negative binomial models using geocoded Indianapolis foreclosure and crime data for 2003–2008 to predict crime counts in 1,000 feet × 1,000 feet square grid cells. Result Foreclosures exhibit consistent positive effects on indices of overall, property, and violent UCR-reported (where UCR is Uniform Crime Report) offenses in a cell and rape, aggravated assault, and burglary counts. In addition, foreclosures had greater effects on reported UCR crimes in stable neighborhoods, especially those with more owner-occupied homes. Conclusion Foreclosures were a robust predictor of crime in the current study