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ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTThe local structure of bismuth strontium copper iron oxide (Bi2.2Sr1.8Cu1-xFexOy) single crystals determined by scanning tunneling microscopyChunming Niu and Charles M. LieberCite this: J. Phys. Chem. 1992, 96, 8, 3419–3423Publication Date (Print):April 1, 1992Publication History Published online1 May 2002Published inissue 1 April 1992https://pubs.acs.org/doi/10.1021/j100187a045https://doi.org/10.1021/j100187a045research-articleACS PublicationsRequest reuse permissionsArticle Views60Altmetric-Citations2LEARN 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 options Get e-Alerts

Faults often separate materials with different elastic properties. Nonuniform slip on such faults induces a change in normal stress. That suggests the possibility of self‐sustained slip pulses [ Weertman , 1980] propagating at the generalized Rayleigh wave speed even with a Coulomb constitutive law (i.e., with a constant coefficient of friction) and a remote driving shear stress that is arbitrarily less than the corresponding frictional strength. Following Andrews and Ben‐Zion [1997] (ABZ), we study numerically, with a two‐dimensional (2‐D) plane strain geometry, the propagation of ruptures along such a dissimilar material interface. However, this problem has been shown to be ill‐posed for a wide range of elastic material contrasts [ Renardy , 1992; Martins and Simões , 1995; Adams , 1995]. Ranjith and Rice [2000] (RR) showed that when the generalized Rayleigh speed exists, as is the case for the material contrast studied by ABZ, the problem is ill‐posed for all values of the coefficient of friction, f , whereas when it does not exist, the problem is ill‐posed only for f greater than a critical value. We illustrate the ill‐posedness by showing that in the unstable range the numerical solutions do not converge through grid size reduction. By contrast, convergence is achieved in the stable range but, not unexpectedly, only dying pulses are then observed. RR showed that among other regularization procedures, use of an experimentally based law [ Prakash and Clifton , 1993; Prakash , 1998], in which the shear strength in response to an abrupt change in normal stress evolves continuously with time or slip toward the corresponding Coulomb strength, provides a regularization. (Classical slip weakening or rate‐ and state‐dependent constitutive laws having the same kind of abrupt response as Coulomb friction also do not regularize the problem.) Convergence through grid size reduction is then achieved in the otherwise ill‐posed range. For sufficiently rapid shear strength evolution, self‐sustained pulses are observed. When the generalized Ray‐leigh wave speed exists, they propagate essentially at that velocity and, in consistence with Weertman 's [1980] analysis, the propagation occurs only in one direction, which is that of slip in the more compliant medium. When the generalized Rayleigh wave speed does not exist, similar self‐sustained pulses propagate at about the slower S wave speed and in the same direction. RR also suggested that for sufficiently high coefficient of friction, another kind of (less unstable) self‐sustained pulses, propagating at a velocity close to the slower P wave speed and in the opposite direction, could also exist. We numerically verify that prediction.

Objective To examine associations of chronic insufficient sleep with diet and whether diet explains the sleep‐adiposity relationship. Methods In Project Viva, 1,046 parents reported children's sleep duration at 6 m and annually until midchildhood (7 y). The main exposure was a sleep curtailment score (6 m‐7 y) ranging from 0 (maximal curtailment) to 13 (adequate sleep). In mid‐childhood, parents reported children's diet; researchers measured height/weight. Multivariable linear regression assessed associations of sleep with diet (Youth Healthy Eating Index [YHEI]); sleep with BMI z ‐score adjusting for YHEI; and, secondarily, joint associations of sleep and YHEI with BMI. Results Mean (SD) sleep and YHEI scores were 10.21 (2.71) and 58.76 (10.37). Longer sleep duration was associated with higher YHEI in mid‐childhood (0.59 points/unit sleep score; 95% CI: 0.32, 0.86). Although higher YHEI was associated with lower BMI z ‐score (−0.07 units/10‐point increase; 95% CI: −0.13, −0.01), adjustment for YHEI did not attenuate sleep‐BMI associations. Children with sleep and YHEI scores below the median (<11 and <60) had BMI z‐scores 0.34 units higher (95% CI: 0.16, 0.51) than children with sleep and YHEI scores above the median. Conclusions While parent‐reported diet did not explain inverse associations of sleep with adiposity, both sufficient sleep and high‐quality diets are important to obesity prevention.

The effect of crystal anisotropy on the formation of grain‐boundary microcracks is analyzed, by considering a planar array of hexagonal grains as a model of a polycrystalline ceramic. The stress singularities at triple‐grain junctions are analyzed by an asymptotic method as well as by a numerical solution, and the critical size of a grain‐boundary defect is investigated by a crack analysis. It is found that elastic anisot‐ropies can significantly increase the stress levels near triple points, which results in a smaller critical grain size for microcracking.

In this paper, we introduce a new agglomerative clustering algorithm in which each pattern cluster is represented by a collection of fuzzy hyperboxes. Initially, a number of such hyperboxes are calculated to represent the pattern samples. Then, the algorithm applies multi-resolution techniques to progressively "combine" these hyperboxes in a hierarchial manner. Such an agglomerative scheme has been found to yield encouraging results in real-world clustering problems.

Recent progress on the synthesis and characterization of semiconductor nanowire heterostructures is reviewed. We describe a general method for heterostructure synthesis based on chemical vapour deposition and the vapour-liquid-solid growth of crystalline semiconducting nanowires. We then examine examples of nanowire heterostructures for which physical properties have been measured, considering the effects of synthetic conditions on the heterointerfaces as well as the electrical and optical characterization measurements that reveal heterointerface formation and quality. Finally, we identify areas of technical and conceptual progress that can contribute to the development of functional nanowire heterostructures.

Abstract To evaluate the association between overall diet and sex hormones concentrations, we collected blood from 578 postmenopausal women ages 43 and 69 years in 1989 or 1990. Food intake was measured in 1990 via a food frequency questionnaire. We calculated the Alternate Healthy Eating Index (AHEI), and dietary patterns were identified by factor analysis. The cross‐sectional association between diet and estrogens, sex hormone binding globulin (SHBG) were evaluated with linear regression and adjusted for energy and other potential confounders. We found a higher AHEI score was associated with lower concentrations of estradiol, free estradiol, and higher concentrations of SHBG. The prudent pattern, with higher intakes of fruits, vegetables, and whole grains, was not associated with any sex hormones. The Western pattern, which represents higher intakes of red and processed meats, refined grains, sweets and desserts, was associated with a higher level of estradiol and lower concentrations of SHBG. Further adjustment for BMI attenuated these results except for free estradiol (5th vs. 1st quintile = 0.09 vs. 0.11 pg/mL, p for trend = 0.03). In addition, the AHEI was inversely associated with estradiol among those with BMI > 25, and Western pattern with SHBG among those with BMI < 25. In conclusion, we observed inverse associations between the AHEI score and several estrogens, and it was positively associated with plasma levels of SHBG. In contrast, the Western pattern was positively associated with estrogen levels and inversely with SHBG. However, these associations appeared to be largely accounted for by BMI. © 2007 Wiley‐Liss, Inc.

High Resolution Electron Energy Loss Spectroscopy (HREELS) has been used to determine the magnitude and temperature dependence of the energy gap for Bi2Sr2CaCu2O8 single crystals cleaved in vacuum. The loss spectra are proportional to the frequency‐dependent resistivity ρ(ω), and thus the energy gap can be determined directly from the onset of ρ(ω), we find that at low temperature 2Δ=6.3kTc and that Δ(T) develops sharply for T<Tc. The similarity of these results to the predictions of models that consider pair‐breaking interactions suggests that higher Tc’s may be obtained in this material.

In a recent editorial, Kristal et al. ([1][1]) asked whether it is time to abandon the food frequency questionnaire (FFQ) for studies of diet and cancer. They highlighted three recent “developments” to cast doubt on the value of the FFQ. The first is the “growing lack of consistency both

Thin-film electrets have been patterned with trapped charge with submicrometer resolution using a flexible, electrically conductive electrode. A poly(dimethylsiloxane) stamp, patterned in bas-relief and supporting an 80-nanometer-thick gold film, is brought into contact with an 80-nanometer-thick film of poly(methylmethacrylate) supported on n-doped silicon. A voltage pulse between the gold film and the silicon transfers charge at the contact areas between the gold and the polymer electret. Areas as large as 1 square centimeter were patterned with trapped charges at a resolution better than 150 nanometers in less than 20 seconds. This process provides a new method for patterning; it suggests possible methods for high-density, charge-based data storage and for high-resolution charge-based printing.