An expanded perspective on children's mental health.

Comments on three articles (see records 2005-11115-003, 2005-11115-004, and 2005-11115-005) on the status of children's mental health services in the United States, which appeared in the September 2005 issue of the American Psychologist. The current authors suggest that, although this series of articles provides important information, the articles fall short in meeting the mark of comprehensively describing the solutions necessary to effectively address the crisis facing children's mental health in this country. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

汽车远程信息的安全性

越来越普及深入的网络连通性要求设计工程师面对并解决范围广阔的技术安全和可靠性问题。目前,许多设备都具有联网的功能,联网设备易受攻击的特性已经成为必须面对的挑战。在开放的网络环境中工作的嵌入式设备越多,安全性就越来越成为事实上每一个嵌入式设计必须面对的技术问题。但是,嵌入式系统开发工程师为了确保始终如一的可靠工作和安全性,通常要付出陡然增加的成本并以延迟上市时间为代价。汽车远程信息系统用于满足嵌入式安全和可靠性的需要,并通过将硬件和软件技术结合,消除过去在安全性、成本和上市时间三者之间所做的不可避免的折…     

Biarc approximation of NURBS curves

An algorithm for approximating arbitrary NURBS curves with biarcs is presented. The main idea is to approximate the NURBS curve with a polygon, and then to approximate the polygon with biarcs to within the required tolerance. The method uses a parametric formulation of biarcs appropriate in geometric design using parametric curves. The method is most useful in numerical control to drive the cutter along straight line or circular paths.     

Product property and production rate control of styrene polymerization

A multivariable multi-rate nonlinear model predictive control (NMPC) strategy is applied to styrene polymerization. The NMPC algorithm incorporates a multi-rate Extended Kalman Filter (EKF) to handle state variable and parameter estimation. A fundamental model is developed for the styrene polymerization CSTR, and control of polymer properties such as number average molecular weight (NAMW) and polydispersity is considered. These properties characterize the final polymer distribution and are strong indicators of the polymer qualities of interest. Production rate control is also demonstrated. Temperature measurements are available frequently while laboratory measurements of concentration and molecular weight distribution are available infrequently with substantial time delays between sampling and analysis. Observability analysis of the augmented system provides guidelines for the design of the augmented disturbance model for use in estimation using the multi-rate EKF. The observability analysis links measurement sets and corresponding observable disturbance models, and shows that measurements of moments of the polymer distribution are essential for good estimation and control. The CSTR is operated at an open-loop unstable steady state. Control simulations are performed under conditions of plant-model structural mismatch and in the presence of parameter uncertainty and disturbances, and the proposed multi-rate NMPC algorithm is shown to provide superior performance compared to linear multi-rate and nonlinear single-rate MPC algorithms. The major contributions of this work are the development of the multi-rate estimator and the measurement design study based on the observability analysis.     

Solubility Limit of MgO in Al2O3 at 1600°C

The solubility of Mg in alumina was measured using wavelength-dispersive spectroscopy mounted on a scanning electron microscope. Careful calibration of the microscope's working conditions was performed in order to optimize the detection limit and accuracy. Measurements were conducted on water-quenched and furnace-cooled samples, without any thermal or chemical etching to avoid alteration of the bulk concentration. The results indicate the solubility limit of Mg in alumina to be 132±11 ppm at 1600°C.     

Structure and digestibility of tissues in normal and brown midrib pearl millet (Pennisetum glaucum)

The tissues in leaf blades, midribs, sheaths and stems of normal (N), 5848, and two brown midrib (bmr) mutants, 5753 and 5778, of pearl millet (Pennisetum glaucum (L) R Br) were examined for structural characteristics related to digestibility. The anatomies of the various plant parts were not substantially different between N and bmr plants. The more rigid, lignified tissues such as vascular bundles in all plant parts and the rind of stems were not digested after incubation for 7 days in N or bmr plants, indicating that modifications in these tissues were not sufficient to affect biodegradation. Modifications in the digestible tissues resulted in faster and more extensive degradation in bmr plants, and these changes appear to be the most significant in relation to biodegradation. The parenchyma of midveins and stems, which occupies c 70 and 60% of the cross-sectional area of these respective parts, were the sites where modification in phenolics resulted in the greatest improvement in digestibility.     

Multicast support for mobile hosts using Mobile IP: Design issues and proposed architecture

In this paper, we consider the problem of providing multicast to mobile hosts using Mobile IP for network routing support. Providing multicast in an internetwork with mobile hosts is made difficult because many multicast protocols are inefficient when faced with frequent membership or location changes. This basic difficulty can be handled in a number of ways, but three main problems emerge with most solutions. The tunnel convergence problem, the duplication problem, and the scoping problem are identified in this paper and a set of solutions are proposed. The paper describes an architecture to support IP multicast for mobile hosts using Mobile IP. The basic unicast routing capability of Mobile IP is used to serve as the foundation for the design of a multicast service facility for mobile hosts. We believe that our scheme is transparent to higher layers, simple, flexible, robust, scalable, and, to the extent possible, independent of the underlying multicast routing facility. For example, our scheme could interoperate with DVMRP, MOSPF, CBT, or PIM in the current Internet. Where differences exist between the current version of IP (IPv4) and the next generation protocol (IPv6), these differences and any further optimizations are discussed. This revised version was published online in June 2006 with corrections to the Cover Date.     

Atomistic simulations of the surfaces of thin films of random copolymers

Amorphous thin films of styrene-butadiene and styrene-butadiene-acrylonitrile copolymers containing a small amount of acrylic acid are generated using molecular dynamics and energy minimization simulations. The structure of the films shows an interior region of bulk density and a thin outer surface layer where the density falls to zero. The surface layer over which the density changes is approximately 5 Å in thickness. The film mass density at its center of mass is close to the bulk values. The orientation function parameter of the backbone carbon-carbon bonds, averaged over the ensemble of representative cells, shows a random nature in the dense region and an inclination towards an orientation somewhat along the plane of the surface layer in the external parts of the film. The styrene rings are mostly located in the bulk region, with random spatial and orientation distributions. The polar groups in the acrylonitrile segment of the SBA films are mostly found in the surface region, where they contribute to the marked enhancement in the surface energy for SBA films compared to SB films. The surface energy values deduced from the models are systematically slightly lower than independent estimates.     

Uncle Sam's crypto road show

State Department documents released to the Electronic Privacy Information Center (EPIC) illustrate the extensive travels of Ambassador David Aaron, President Clinton's former Special Envoy for Cryptography, during 1996 and 1997. On 6 November 1996, Aaron became the Under Secretary of Commerce for international trade. Aaron was charged by the Clinton administration with selling the concept of the unpopular key escrow/key recovery initiatives to governments around the world. This was in addition to his other duties as Permanent Representative to the Organization for Economic Cooperation and Development (OECD) in Paris.