A paraxial theory for the propagation of ultrasonic beams in anisotropic solids

The necessity of nondestructively inspecting cast steels, weldments, composites, and other inherently anisotropic materials has stimulated considerable interest in wave propagation in anisotropic media. Here, the problem of an ultrasonic beam traveling in an anisotropic medium is formulated in terms of an angular spectrum of plane waves. Through the use of small angle approximations, the integral representation is reduced to a summation of Gauss–Hermite eigensolutions. The anisotropic effects of beam skew and excess beam divergence enter into the solution through parameters that are simply interpreted in terms of the slowness surface. Both time harmonic and pulsed solutions are discussed. Formulas are also presented for transmission of a beam through a curved interface between two media. Examples are given illustrating how this method may be applied to predicting beam patterns during ultrasonic inspections

What factors influence healthcare professionals to refer children and families to paediatric psychology?

Objectives: This study aimed to investigate factors influencing referral of children with physical illness to paediatric psychology. Due to high rates of mental health problems within this population, studies have shown that referral to paediatric psychology should be increased. However, few studies have examined factors shaping healthcare professionals’ referral behaviour. Methods: The current study used the theory of planned behaviour to develop a questionnaire which explores factors influencing the referral of children and families to paediatric psychology. Psychometric properties of the questionnaire were examined. Results: The questionnaire was found to have good reliability and validity. The main constructs of the theory of planned behaviour were useful in predicting intention to refer to paediatric psychology. Specific beliefs about referral were shown to influence intention to refer. Conclusions: Findings suggest that individual attitudes and beliefs can impact healthcare professionals’ referral behaviour, indicating that multidisciplinary interventions and inter-professional education relating to the psychological aspects of illness are required

The effect of flow velocity and tile joint spacing and misalignment on the head exerted against soil surrounding farm drain tile

This bulletin is a report on Department of Agricultural Engineering research project 43, 'Terracing'--P. [3].Digitized 2007 AES.Includes bibliographical references (page 14)

Religion, Delinquency, and Drug Use: A Meta-Analysis

Contemporary research on adolescent involvement in religion and delinquency is generally traced to Hirschi and Stark’s 1969 study, titled ‘‘Hellfire and Delinquency.’’ Their study surprised many by reporting no significant relationship between religious involvement and delinquency. Subsequent replications provided mixed results, but multiple reviews, both traditional and systematic, found religious involvement to be inversely related to delinquency. However, meta-analysis of the relationship remains scant with only three studies published to date. To address this research need, we conducted a meta-analysis of 62 relevant studies over four decades, which provided 145 effect sizes from 193,656 adolescents. We examined six bivariate correlations between two, attitudinal and behavioral, measures of religious involvement (religiosity and church attendance) and three indicators of delinquent behavior (alcohol use, illicit drug use, and nondrug delinquency). Our meta-analysis results indicated an inverse relationship among all correlations (range: -.16 to -.22). Stated differently, the results of this meta-analysis confirmed that religious involvement is negatively related to delinquent behaviors, regardless of measurement characteristics. The implications of this finding for future research on religion and delinquency are discussed

Altimetric system: Earth observing system. Volume 2h: Panel report

A rationale and recommendations for planning, implementing, and operating an altimetric system aboard the Earth observing system (Eos) spacecraft is provided. In keeping with the recommendations of the Eos Science and Mission Requirements Working Group, a complete altimetric system is defined that is capable of perpetuating the data set to be derived from TOPEX/Poseidon, enabling key scientific questions to be addressed. Since the scientific utility and technical maturity of spaceborne radar altimeters is well documented, the discussion is limited to highlighting those Eos-specific considerations that materially impact upon radar altimetric measurements

Fire and plant diversification in mediterranean-climate regions

Despite decades of broad interest in global patterns of biodiversity, little attention has been given to understanding the remarkable levels of plant diversity present in the world’s five Mediterranean-type climate (MTC) regions, all of which are considered to be biodiversity hotspots. Comprising the Mediterranean Basin, California, central Chile, the Cape Region of South Africa, and southwestern Australia, these regions share the unusual climatic regime of mild wet winters and warm dry summers. Despite their small extent, covering only about 2.2% of world land area, these regions are home to approximately one-sixth of the world vascular plant flora. The onset of MTCs in the middle Miocene brought summer drought, a novel climatic condition, but also a regime of recurrent fire. Fire has been a significant agent of selection in assembling the modern floras of four of the five MTC regions, with central Chile an exception following the uplift of the Andes in the middle Miocene. Selection for persistence in a fire-prone environment as a key causal factor for species diversification in MTC regions has been under-appreciated or ignored. Mechanisms for fire-driven speciation are diverse and may include both directional (novel traits) and stabilizing selection (retained traits) for appropriate morphological and life-history traits. Both museum and nursery hypotheses have important relevance in explaining the extant species richness of the MTC floras, with fire as a strong stimulant for diversification in a manner distinct from other temperate floras. Spatial and temporal niche separation across topographic, climatic and edaphic gradients has occurred in all five regions. The Mediterranean Basin, California, and central Chile are seen as nurseries for strong but not spectacular rates of Neogene diversification, while the older landscapes of southwestern Australia and the Cape Region show significant components of both Paleogene and younger Neogene speciation in their diversity. Low rates of extinction suggesting a long association with fire more than high rates of speciation have been key to the extant levels of species richness

Weather, Crime, and Mental Illness

ABSTRACT - A simple count of disturbed incidents in the mentally ill and total radio transmissions of the Minneapolis Police Departmenf were collected daily over a six-month period. These were correlated with calendar time, temperature, humidity, and barometric pressure for the same period. Separate comparisons were made of all these measures for December 1959 with those of other Decembers. All the weather variables correlated linearly and significantly with the behavior v.ariables; temperature and humidity, positively; barometric pressure negatively. Calendar time for the half year correlated linearly and negatively. December 1959 had a higher crime and mental disturbance rate than other Decembers; this was accompanied by higher temperature and humidity

The streamwater microbiome encodes hydrologic data across scales

Many fundamental questions in hydrology remain unanswered due to the limited information that can be extracted from existing data sources. Microbial communities constitute a novel type of environmental data, as they are comprised of many thousands of taxonomically and functionally diverse groups known to respond to both biotic and abiotic environmental factors. As such, these microscale communities reflect a range of macroscale conditions and characteristics, some of which also drive hydrologic regimes. Here, we assess the extent to which streamwater microbial communities (as characterized by 16S gene amplicon sequence abundance) encode information about catchment hydrology across scales. We analyzed 64 summer streamwater DNA samples collected from subcatchments within the Willamette, Deschutes, and John Day river basins in Oregon, USA, which range 0.03–29,000 km2 in area and 343–2334 mm/year of precipitation. We applied information theory to quantify the breadth and depth of information about common hydrologic metrics encoded within microbial taxa. Of the 256 microbial taxa that spanned all three watersheds, we found 9.6 % (24.5/256) of taxa, on average, shared information with a given hydrologic metric, with a median 15.6 % (range = 12.4–49.2 %) reduction in uncertainty of that metric based on knowledge of the microbial biogeography. All of the hydrologic metrics we assessed, including daily discharge at different time lags, mean monthly discharge, and seasonal high and low flow durations were encoded within the microbial community. Summer microbial taxa shared the most information with winter mean flows. Our study demonstrates quantifiable relationships between streamwater microbial taxa and hydrologic metrics at different scales, likely resulting from the integration of multiple overlapping drivers of each. Streamwater microbial communities are rich sources of information that may contribute fresh insight to unresolved hydrologic questions

Dipolar Interactions and Origin of Spin Ice in Ising Pyrochlore Magnets

Recent experiments suggest that the Ising pyrochlore magnets ${\rm Ho_{2}Ti_{2}O_{7}}$ and ${\rm Dy_{2}Ti_{2}O_{7}}$ display qualitative properties of the spin ice model proposed by Harris {\it et al.} \prl {\bf 79}, 2554 (1997). We discuss the dipolar energy scale present in both these materials and consider how they can display spin ice behavior {\it despite} the presence of long range interactions. Specifically, we present numerical simulations and a mean field analysis of pyrochlore Ising systems in the presence of nearest neighbor exchange and long range dipolar interactions. We find that two possible phases can occur, a long range ordered antiferromagnetic one and the other dominated by spin ice features. Our quantitative theory is in very good agreement with experimental data on both ${\rm Ho_{2}Ti_{2}O_{7}}$ and ${\rm Dy_{2}Ti_{2}O_{7}}$. We suggest that the nearest neighbor exchange in ${\rm Dy_{2}Ti_{2}O_{7}}$ is {\it antiferromagnetic} and that spin ice behavior is induced by long range dipolar interactions.Comment: 4 postscript figures included. Submitted to Physical Review Letters Contact: [email protected]

Application of Models for IGSCC Inspection

Ultrasonic detection and sizing of intergranular stress corrosion cracks (IGSCC) in nuclear reactor cooling systems is a difficult practical problem due to the complicated geometry of these defects and to the variety of other reflectors (e. g., welds) which produce competing ultrasonic indications. The use of models of scattering from such defects can help in improving physical insight into ultrasonic scattering from IGSCC’s and may ultimately be of use in defining inspection protocols and signal processing algorithms which can lead to improved inspection reliability and discrimination between IGSCC’s and other geometrical reflectors. This paper will discuss the application of a model of ultrasonic scattering from a simple Y-shaped crack based upon the Kirchhoff approximation. In this model, the ultrasonic beam is approximated by a Gaussian profile which includes the effects of diffraction and allows calculation of the full ultrasonic radiation pattern which may be used, for example, to simulate a scanned inspection. Included in this paper will be a brief description of the model and a presentation of simulated IGSCC results. Comparisons of the model to experimental measurements will then be addressed followed by an application to the problem of IGSCC sizing based upon the dB-drop and PAT (pulse-arrival-time) techniques