ABSTRACT. A random sample of 3 206 seven‐year‐old children was studied in order to examine the prevalence of enuresis and associated somatic and genetic risk factors. The overall prevalence of enuresis was 9.8% and the figures for nightwetting, day wetting and mixed day and night wetting 6.4%, 1.8% and 1.6% respectively. The prevalence was 9.5% among primary school children, 24.8% among children whose entry to school had been postponed and 26.6% among handicapped and mentally retarded children. If the father had been enuretic after 4 years of age the risk of the child being enuretic was 7.1 times greater than otherwise (95% confidence limits of the risk ratio 5.1–9.8, p < 0.001), the corresponding risk ratio when the mother had been enuretic being 5.2 (3.9–7.0, p < 0.001). Low birth‐weight children were enuretic more often than children of normal birth‐weight. It seems that there are at least two aetiologically significant groups of enuretic children: cases with neurological damage and mixed day and night wetting and cases with delayed maturation, with nightwetting which shows a clear sex and genetic dependency.
A new collocation method based on quadratic splines is presented for second order two‐point boundary value problems. First, O ( h 4 ) approximations to the first and second derivative of a function are derived using a quadratic‐spline interpolant of u. Then these approximations are used to define an O ( h 4 ) perturbation of the given boundary value problem. Second, the perturbed problem is used to define a collocation approximation at interval midpoints for which an optimal O ( h 3‐J ) global estimate for the j th derivative of the error is derived. Further, O ( h 4‐J ) error bounds for the j th derivative are obtained for certain superconvergence points. It should be observed that standard collocation at midpoints gives O ( h 2‐J ) bounds. Results from numerical experiments are reported that verify the theoretical behaviour of the method.
The merger of nanoscale devices with flexible, low cost plastics could enable a broad spectrum of electronic and photonic applications, although difficulties in processing plastics at the nanoscale have limited exploration of this potential. Here we describe the use of room temperature nanoimprint lithography for the general fabrication of nanometer- through millimeter-scale patterns on polymer substrates. Specifically, we demonstrate the patterning of arrays of nanoscale source−drain electrode pairs with continuous interconnects to the millimeter length scale, and the fabrication of hundred-nanometer gate features hierarchically patterned over large areas. These patterned plastic substrates have also been used in conjunction with semiconductor nanowires to assemble field-effect transistors.
A significant fraction of the insight and understanding needed to understand mixedmode fracture can be obtained by considering a simple elastic bilayer consisting of two thin layers bonded together, with a semi-infinite crack lying on the interface. The concepts and results generated for the bilayer in this chapter are extended to multilayers consisting of many layers in Chapter 5. Additional aspects of interface fracture in bilayers are discussed throughout subsequent chapters, but notably Chapter 7 (kinking out of the interface), Chapter 9 (finite-sized edge flaws) and Chapter 12 (temperature gradients).
Constitutive relations for fault slip are described and adopted as a basis for analyzing slip motion and its instability in the form of earthquakes on crus
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSynthesis and reactions of bis(cyclopentadienyl)titanium(IV) metallocyclesJoseph X. McDermott, Michael E. Wilson, and George M. WhitesidesCite this: J. Am. Chem. Soc. 1976, 98, 21, 6529–6536Publication Date (Print):October 1, 1976Publication History Published online1 May 2002Published inissue 1 October 1976https://doi.org/10.1021/ja00437a019RIGHTS & PERMISSIONSArticle Views931Altmetric-Citations180LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (1 MB) Get e-Alerts Get e-Alerts
This paper describes dynamic self-assembly of millimeter-sized, magnetized disks floating at two parallel interfaces and spinning under the influence of a rotating, external magnetic field. All disks experience a central, confining magnetic potential, and interact with one another hydrodynamically both in the plane of the interface, and between the interfaces. The interactions between the disks spinning on different interfaces are repulsive for low rotational speeds, and attractive for high rotational speeds. The interplay between magnetic and hydrodynamic forces acting in the system leads to the formation of quasi three-dimensional, ordered aggregates. Changing the rotation speeds of the disks can reversibly change the morphologies of these aggregates.
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSurface Plasmon Resonance Permits in Situ Measurement of Protein Adsorption on Self-Assembled Monolayers of Alkanethiolates on GoldMilan Mrksich, George B. Sigal, and George M. WhitesidesCite this: Langmuir 1995, 11, 11, 4383–4385Publication Date (Print):November 1, 1995Publication History Published online1 May 2002Published inissue 1 November 1995https://pubs.acs.org/doi/10.1021/la00011a034https://doi.org/10.1021/la00011a034research-articleACS PublicationsRequest reuse permissionsArticle Views1799Altmetric-Citations312LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose Get e-Alerts
In an extension of earlier studies by Rice and Sorensen, a discussion is presented on the elastic-plastic stress and deformation fields at the tip of a crack which grows in an ideally plastic solid under plane strain, small-scale yielding conditions. The results of an asymptotic analysis suggest the existence of a crack-tip stress state similar to that of the classical Prandtl field, but containing a zone of elastic unloading between the centered fan region and the trailing constant stress plastic region. The near tip expression for the rate of opening displacement δ at distance r from the growing tip is found to have the same form suggested by Rice and Sorensen ˙δ=α˙J∕σo+β(σo∕E)˙aln(R∕r) but now the presence of the elastic wedge causes β to have the revised value of 5.08 (for Poisson ratio ν = 0.3). Here, a = crack length, σo = yield strength, E = elastic modulus, and J denotes the far-field value, namely, (1 − ν2)K2/E for the small scale yielding conditions considered. The parameters α and R cannot be determined from the asymptotic analysis, but comparisons with finite element solutions suggest that, at least for small amounts of growth, α is approximately the same for stationary and growing cracks, and R scales approximately with the size of the plastic zone, being about 15 percent to 30 percent larger. For large scale yielding it is argued that a similar form applies with possible variations in α and β, at least in cases which maintain triaxial constraint at the crack tip, but in the fully yielded case R is expected to be proportional to the dimension of the uncracked ligament. The model crack growth criterion of Rice and Sorensen, requiring a critical δ at some fixed r from the tip, is reexamined in light of the more accurate solution. The results suggest that the J versus Δa relation describing growth will be dependent on the extent of yielding, although it is suggested that this dependency might be small for highly ductile materials, provided that a similar triaxial constraint is maintained in all cases.
It is shown that the J-integral can be directly evaluated from single load-displacement records for a series of crack toughness specimens having the common feature that their only significant length dimension is that of the uncracked ligament. For the special case of bending loads on the ligament of a deeply cracked bar, J is shown to be twice the work of deformation divided by the ligament area. This and like results are employed to discuss Charpy and “equivalent energy” toughness measures and also to evolve yet simpler estimating procedures for the J-integral.
Computer science is at heart an applied field. In the current US economic and political climate, where projects not applicable to "strategic" research are less likely to be funded, computational science and engineering applications will become a driving force behind all aspects of computing research. The paper discusses this shift towards the funding of strategic research.
