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An indirect boundary element method (IBEM) is developed to study the dynamic impedance functions (stiffness coefficients) of a rigid strip foundation embedded in a multi-layered viscoelastic transversely isotropic (TI) half-space. The proposed IBEM using half-space Green’s functions of distributed loads as fundamental solutions have the merits of fictitious loads being directly applied on the real boundaries without the problem of singularity and of the discretization effort restricted to local boundaries. In addition, the accuracy of the proposed method is not affected by the thickness of the discrete TI layers, as the exact dynamic stiffness matrix is employed. The presented algorithm is verified via comparisons with published results for the isotropic medium. By taking a rigid strip foundation embedded in a homogeneous half-space, a single-layered half-space, and a multi-layered half-space as examples, the effects of material anisotropy, frequency of excitation, and soil layer on the impedance functions are studied in detail. Numerical results show that impedance functions for the TI medium can be significantly different from those of the isotropic case. The variation of TI parameters alters the dynamic characteristics of the TI layered site, which in turn alters the dynamic interaction between the soil and foundation. In addition, the soil sedimentary sequence also has a remarkable influence on the impedance functions. [ABSTRACT FROM AUTHOR]

This paper is the second of the two papers, discussing the rocking and resultant component of rotations, with the torsional components of motions presented earlier in the first paper for the case of out-of-plane SH waves excitation on a semi-parabolic canyon. The rotational motions are gaining importance in recent years in the field of strong-motion seismology and earthquake engineering. Many previous papers on out-of-plane SH waves excitation presented the associated torsion rotational motions, when in fact there is also a rocking rotational component of motions. Both the rocking and torsion rotational motions, in as much as the translational motions, had shown to play an important role in structural responses, even though rotations are not incorporated into building design codes at present. Studying the rotational motions can thus help to a better understanding of the behavior of surface topographies that are in the vicinity of structures in the event of seismic excitation. This paper included, besides the additional rocking motions, also the resultant rotational motions combining torsion and rocking. [ABSTRACT FROM PUBLISHER]

The surface displacement amplitudes excited by out-of-plane SH waves on and around a semi-parabolic canyon had solution that was introduced over twenty years ago. In 2015, such solution was updated to much (5 times) higher frequencies, using a transformation involving the Wronskian. The same excitations also introduce rotations on and around the parabolic canyon. This article is the first of two that discuss the torsional component of rotations, with the rocking components discussed in the subsequent article. The rotational amplitudes of motions, as much as the displacement amplitudes, play an important role in studying the surface responses of structures, and can lead to a better understanding of the behavior of surface topographies in the event of seismic excitation. [ABSTRACT FROM PUBLISHER]

This article examines the issue of parental self-efficacy in guiding and supervising children to use mobile devices in Hong Kong. Data were collected from a sample of 1,561 students and 1,233 of their parents. Multiple hierarchical regression analyses showed that the frequency with which parents adopted involvement as a parenting method and the frequency of minor parent–child conflicts triggered by parental supervision were significantly associated with parental self-efficacy in supervising children to use mobile devices. Findings suggest that support for parents to adopt involvement methods more frequently and better manage parent–child conflicts are crucial in enhancing their self-efficacy. [ABSTRACT FROM PUBLISHER]

A closed-form wave function analytic solution of two-dimensional scattering and diffraction of incident plane SH-waves by a shallow semi-elliptical hill with a concentric elliptical tunnel on an elastic half-space is presented. This research extends the previous solution by authors in 2013 which addressed only the semi-elliptical hill, to a hill-tunnel system. Ground surface displacement near the hill are studied and exhibited. It was observed from the results that the aspect ratio of hill and tunnel profiles, frequency of incident waves, and incident angles are the primary factors that may affect the surface ground motion amplitudes near the hill-tunnel system. [ABSTRACT FROM PUBLISHER]

The surface displacement in the vicinity of a semi-parabolic canyon was solved over 20 years ago. Previous study presented results only for a range of low frequencies, with computational difficulty coming from convergence of the Weber wave functions. We revisit this problem and employ new algorithm computing results at much higher frequencies for surface spectral displacements on the parabolic canyon by incident SH-waves. A transformation with the Wronskian allows computing displacement up to dimensionless frequency ofthen tonow! In terms of wavelength, the displacements were computed for waves with wavelengths five times smaller, or frequencies five times higher, a great improvement! [ABSTRACT FROM PUBLISHER]

Objective: To evaluate the plasma levels of angiogenic factors in preeclampsia (PE) and intrauterine fetal growth restriction (IUGR) and their potential as biomarkers to distinguish normal from pathologic pregnancies. Methods: Case control study included singleton pregnancies in four categories: (i) normal ( n = 29), (ii) PE ( n = 15), (iii) PE and IUGR ( n = 16) and (iv) IUGR ( n = 24). The classification of IUGR included umbilical artery Doppler resistance. Maternal plasma placental growth factor (PlGF), soluble fms-like tyrosine kinase-1 (sFlt-1), soluble kinase domain receptor (sKDR) and soluble endoglin (sEng) as well as fetal umbilical artery sFlt-1 levels were determined. Each individual marker and their ratios were assessed for their potential to distinguish normal pregnancy from pregnancies affected by PE and/or IUGR. Results: We found (i) elevated plasma sFlt-1, sEng and reduced PlGF, sKDR in PE and IUGR; (ii) similar angiogenic profiles in PE and IUGR and (iii) sEng and sFlt-1*sEng/PlGF performed best as biomarkers in identifying pathologic pregnancies. Conclusions: PE and IUGR have similar angiogenic profiles, suggesting that angiogenic marker profiles lack specificity in identifying PE and that other factors are required for the development of PE instead of IUGR. sEng should be included in a biomarker profile for predicting PE or IUGR. [ABSTRACT FROM AUTHOR]

A closed-form wave function analytic solution is presented in this article regarding the two-dimensional scattering and diffraction of a flexible wall sitting on a rigid shallow circular foundation embedded in an elastic half-space that is activated by a nearby anti-plane line source such as a blast caused by underground construction or mineral exploration or a near-field fault rupture, using similar methodology as the other paper in a series [Lee and Luo, 2013]. These wave propagation influences, although often treated as a transient process, may be simulated as linear combinations of steady-simple harmonic responses as studied in this article. Ground surface displacements spectra for wide-band of incident wave frequencies are calculated. Based on the spectra obtained, the dependence of near-field ground displacements are shown with respect to the rise-to-span ratio of foundation profile, frequency of incident waves, distance of source from the foundation, and mass ratios of various media (foundation-structure-soil). The screening effect of rigid foundation upon ground motions behind grazing incident waves is also presented. [ABSTRACT FROM PUBLISHER]

The cost of caring for an aging population is a growing concern in many societies. Although information and communication technologies (ICTs) like computers and the Internet are seen as new tools which offer some potential to help, unfortunately older adults are generally the age group with the lowest level of skill and utilization of these technologies. Although nongovernmental organizations have attempted to address this digital gap, limited staff resources are a concern. One approach for generating additional staff to provide more technology training to older adults is a 'peer-tutor' model. This study examined the perspectives of 101 technology peer tutors for older adults in a nonprofit program in Hong Kong. Topics included preparation and training, perceived benefits and challenges, side effects on their lives, the perceived value of their work as tutors, and suggestions for personal and program improvement. The influence of demographic factors was examined. Results show which tutors felt prepared for their roles, perceived considerably more benefits than challenges, saw value in their tutor work, and overwhelming plan to continue as volunteer tutors in this program. There were few differences linked with demographic variables. Implications for practice and for future research are considered. [ABSTRACT FROM AUTHOR]