A geographical analysis of multiethnic households in the United States

"Using the household-level data provided by the 5% PUMS [Public Use Microdata Sample] data from the 1990 Census, this paper reports the pattern of ethnic mixing at the household level in the U.S. and also describes the geographical patterns of different types of multiethnic households at both the state level and the PUMA [Public Use Microdata Area] level. Several of the largest metropolitan areas are also examined in greater detail. The strong dominance of whites in the process of ethnic mixing is clear, as is the expected dominance of blacks in southeastern U.S. and the dominance of Hispanics in the southwest at the state level. The PUMA-level analysis reveals local clusters of ethnic mixing that are not apparent at the state-level analysis."     

Effects of pressure on the micromechanics of faulting in San Marcos gabbro

Samples of San Marcos gabbro were deformed to both pre- and post-failure stages at confining pressures of 100, 250 and 350 MPa. Scanning electron microscope observations were performed on the samples after ion-milling. The unstressed gabbro has insignificant crack porosity but a high volume fraction of healed and sealed cracks. Extensive stress-induced cracking at high angles to the maximum compressive stress is observed at the two higher pressures. Such high-angle cracks are mostly associated with the pre-existing healed cracks or cleavage planes, and they control the geometry and length scale of crack networks in plagioclase. Intensive kinking in biotite is widely observed at 350 MPa pressure, which together with the crack networks control the brittle fracture process. Stress-induced cracks in samples deformed at 100 MPa pressure are predominantly subparallel to the maximum compressive stress, and their coalescence leads to shear localization.Quantitative measurements of crack density as a function of differential stress indicate that crack interaction is appreciable beyond about 90% peak stress for all three pressures. The data also show significant decreases in stress-induced anisotropy as pressure increases, suggesting that there may be a threshold pressure beyond which stress-induced anisotropy vanishes with the onset of cataclasis.     

The distribution of particulate iodine in the Atlantic Ocean

The iodine content of marine suspended matter obtained from thirteen stations in the Atlantic between 75°N and 55°S has been measured. The concentration of particulate iodine is high in the surface, up to 127 ng/kg of seawater being observed. Below the euphotic zone, it drops sharply to 1–2 ng/kg. The iodine-containing particles are probably biogenic. A simple box-model calculation shows that only 3% of the particulate iodine produced in the surface water may reach the deep sea and that the residence time of these particles in the surface water is about 0.1 year.     

Seismic displacements of torsionally unbalanced buildings

A parametric study is carried out to evaluate the seismic displacements at the flexible edge of torsionally unbalanced (TU) structural systems. Guidelines are provided to estimate these displacements so that they can be incorporated in the formulation of the displacement-based seismic design approach for the design of TU buildings. The ability of three code procedures to estimate the flexible-edge displacement is examined to show that not all procedures lead to conservative estimates. Finally, it is shown that elastic spectrum analysis incorporating accidental torsion effect is a viable means to estimate the flexible-edge displacements.     

无穷介质中含井孔的热固结问题

多孔介质热固结是一个温度、孔隙压力、变形和应力之间的耦合问题.通过对控制方程解耦,并使用拉普拉斯变换,给出了边界上为常温、孔隙压力梯度为零的无穷介质中含有井孔的热固结问题的解析解,包括热应力场、温度分布以及孔隙压力分布.     

A Spatial Decision Support System Approach to Evaluate the Efficiency of a Meals-on-Wheels Program*

Due to limited resources, publicly funded service programs need to operate efficiently. This paper demonstrates how a Spatial Decision Support System (SDSS) can be used to evaluate and enhance the performance of an existing service delivery program. Elements critical to the efficiency of service programs are enumerated. A meals-on-wheels (MOW) program in Connecticut is used as a case study to demonstrate the utility of the SDSS approach. Practical issues related to data sources and system adoption are discussed.     

Inelastic seismic response of torsionally unbalanced systems designed using elastic dynamic analysis

This paper evaluates the inelastic seismic response of torsionally unbalanced structural systems with strength distributed using elastic response spectrum analysis. The structural model is a single mass torsionally unbalanced system with lateral load resisting elements spanning in two principal directions. The element strength is distributed based on elastic response spectrum analysis and three different approaches to incorporate accidental torsion are considered: (a) without incorporating accidental torsion; (b) by applying static floor torques; (c) by shifting the location of the centre of mass. The seismic input is bidirectionally applied at the base of the model. It is shown that the inelastic responses depend strongly on the torsional stiffness of the system. For a torsionally stiff system, the torsional response leads to a decrease in the stiff edge displacement; however, for a torsionally flexible system, it tends to increase the stiff edge displacement. Using response spectrum analysis without including accidental torsion may lead to excessive additional ductility demand on the stiff edge element. With accidental torsion effect incorporated, the response spectrum analysis will give a strength distribution such that there will be no excessive additional ductility demands on the lateral load resisting elements.     

Three-dimensional response of a cylindrical canyon in a layered half-space

An indirect boundary-method formulation to obtain the three-dimensional response of an infinitely long canyon of uniform but arbitrary cross-section cut in a layered viscoelastic half-space is presented. Seismic excitation in the form of plane elastic waves acting at an arbitrary angle with respect to the axis of the canyon is considered. Numerical results for SH-, SV- and P-wave excitation of a circular canyon and of a canyon with a topography similar to that in the vicinity of Pacoima Dam are discussed in some detail.     

Isolation of soil-structure interaction effects by full-scale forced vibration tests

Forced vibration tests designed to isolate the effects of soil-structure interaction are described and the results obtained for the nine-storey reinforced concrete Millikan Library Building are analysed. It is shown that it is possible to determine experimentally the fixed-base natural frequencies and modal damping ratios of the superstructure. These values may be significantly different from the resonant frequencies and damping ratios of the complete structure-foundation-soil system. It is also shown that forced vibration tests can be used to obtain estimates of the foundation impedance functions. In the case of the Millikan Library it is found that during forced vibration tests the rigid-body motion associated with translation and rocking of the base accounts for more than 30 per cent of the total response on the roof and that the deformation of the superstructure at the fundamental frequencies of the system is almost entirely due to the inertial forces generated by translation and rocking of the base.     

Pigment analysis and spectral assessment of spruce trees undergoing forest decline in the NE United States and Germany

Measurement of photosynthetic pigments as ground truth for remotely sensed spectra of boreal communities was tested. Chlorophyll and carotenoid concentrations and ratios were obtained from needles of spruce trees which were healthy as well as those undergoing forest decline (Waldsterben) in Vermont (USA) and Baden-Württemberg (FR Germany). In needles of trees exhibiting forest decline symptoms, chlorophyll pigment concentrations were lower, chlorophyll b levels decreased relative to chlorophyll a, total chlorophyll (a + b) was less relative to total carotenoid, and percent of reflectance in the visible range was higher. Pigment and reflectance data differentiated between needles from healthy and declining sites. These results were compared to remotely sensed spectral data obtained by aircraft and satelitee. As a result of these initial comparisons, it appears that using photosynthetic pigments as ground truth for remotely sensed spectral data may be of value in developing techniques for differentiating undamaged and damaged tree canopies on a large spatial scale. Finally, similar pigment and reflectance properties characterized healthy and declining communities in both Vermont and Baden-Württemberg.