Abstract Because of several anomalies in a publication that we coauthored, concerning the interaction of the Arabidopsis cobra protein with crystalline cellulose (Avicel) and individual glucan chains (cellohexaose) we reexamined the data and had an independent laboratory redo a key experiment. The results show that COBRA binds to cellohexaose preferably over binding to Avicel, confirming our previous report.
In this paper we consider impulsive control of master-slave synchronization schemes that consist of identical Lur'e systems. Impulsive control laws are investigated which make use of linear or nonlinear dynamic measurement feedback. A sufficient condition for global asymptotic stability is presented which is characterized by a set of matrix inequalities. Synchronization is proven for the error between the output signals. The method is illustrated on Chua's circuit and a hyperchaotic system with coupled Chua's circuits.
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTThe Measurement of Surface Area in Gas-Particulate SystemsAlexis T. Bell and Donald N. HansonCite this: Ind. Eng. Chem. Fundamen. 1973, 12, 1, 127–129Publication Date (Print):February 1, 1973Publication History Published online1 May 2002Published inissue 1 February 1973https://pubs.acs.org/doi/10.1021/i160045a022https://doi.org/10.1021/i160045a022research-articleACS PublicationsRequest reuse permissionsArticle Views35Altmetric-Citations1LEARN 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
The rapid increase in web usage has led to dramatically increased loads on the network infrastructure and on individual web servers. To ameliorate these mounting burdens, there has been much recent interest in web caching architectures and algorithms. Web caching reduces network load, server load, and the latency of responses. However, web caching has the disadvantage that the pages returned to clients by caches may be stale, in that they may not be consistent with the version currently on the server. In this paper we describe a scalable web cache consistency architecture that provides fairly tight bounds on the staleness of pages. Our architecture borrows heavily from the literature, and can best be described as an invalidation approach made scalable by using a caching hierarchy and application-level multicast routing to convey the invalidations. We evaluate this design with calculations and simulations, and compare it to several other approaches.
Community health partnerships (CHPs) are voluntary collaborations of diverse community organizations that have joined forces in order to pursue a shared interest in improving community health. Although these cross‐sectoral collaborations represent a way to address social determinants of health and disease in society, they suffer from governance and management problems associated with interorganizational relationships in general and health care challenges specifically. A typology of effective governance and management characteristics provides a systematic, theoretically based way of addressing dimensions of governance and management and serves as a guide in constructing, maintaining, and measuring successful partnerships. It offers a multidisciplinary perspective for classifying important organizational issues, identifying barriers to successful development and sustainability, and facilitating the attainment of goals.
We review the use of Type Ia supernovae for cosmological distance determinations. Low-redshift SNe Ia (z < 0.1) demonstrate that (a) the Hubble expansion is linear, (b) H_0 = 65 +/- 2 (statistical) km/s/Mpc, (c) the bulk motion of the Local Group is consistent with the COBE result, and (d) the properties of dust in other galaxies are similar to those of dust in the Milky Way. We find that the light curves of high-redshift (z = 0.3-1) SNe Ia are stretched in a manner consistent with the expansion of space; similarly, their spectra exhibit slower temporal evolution (by a factor of 1 + z) than those of nearby SNe Ia. The luminosity distances of our first set of 16 high-redshift SNe Ia are, on average, 10-15% farther than expected in a low mass-density (Omega_M=0.2) universe without a cosmological constant. Preliminary analysis of our second set of 9 SNe Ia is consistent with this. Our work strongly supports eternally expanding models with positive cosmological constant and a current acceleration of the expansion. We address many potential sources of systematic error; at present, none of them reconciles the data with Omega_Lambda=0 and q_0 >= 0. The dynamical age of the Universe is estimated to be 14.2 +/- 1.7 Gyr, consistent with the ages of globular star clusters.
Abstract Background Restaurant workers have among the highest rates of work‐related illness and injury in the US, but little is known about the working conditions and occupational health status of Chinese immigrant restaurant workers. Methods Community‐based participatory research (CBPR) was employed to study restaurant working conditions and worker health in San Francisco's Chinatown. A community/academic/health department collaborative was formed and 23 restaurant workers trained on research techniques and worker health and safety. A worker survey instrument and a restaurant observational checklist were collaboratively developed. The checklist was piloted in 71 Chinatown restaurants, and the questionnaire administered to 433 restaurant workers. Results Restaurant workers, together with other partners, made substantial contributions to construction of the survey and checklist tools and improved their cultural appropriateness. The utility of the checklist tool for restaurant‐level data collection was demonstrated. Conclusions CBPR holds promise for both studying worker health and safety among immigrant Chinese restaurant workers and developing culturally appropriate research tools. A new observational checklist also has potential for restaurant‐level data collection on worker health and safety conditions. Am. J. Ind. Med. 53:361–371, 2010. © 2010 Wiley‐Liss, Inc.
We present optical spectropolarimetry obtained at the Keck-II 10-m telescope on 1998 March 7 UT along with total flux spectra spanning the first 494 days after discovery (1998 March 2 UT) of the peculiar type IIn supernova (SN) 1998S. The SN is found to exhibit a high degree of linear polarization, implying significant asphericity for its continuum-scattering environment. Prior to removal of the interstellar polarization, the polarization spectrum is characterized by a flat continuum (at p ~ 2%) with distinct changes in polarization associated with both the broad (FWZI >= 20,000 km/s) and narrow (unresolved, FWHM < 300 km/s) line emission seen in the total flux spectrum. When analyzed in terms of a polarized continuum with unpolarized broad-line recombination emission, an intrinsic continuum polarization of p ~ 3% results (the highest yet found for a SN), suggesting a global asphericity of >= 45% from the oblate, electron-scattering dominated models of Hoflich (1991). The smooth, blue continuum evident at early times is shown to be inconsistent with a reddened, single-temperature blackbody, instead having a color temperature that increases with decreasing wavelength. Broad emission-line profiles with distinct blue and red peaks are seen in the total flux spectra at later times, perhaps suggesting a disk-like or ring-like morphology for the dense (n_e ~ 10^7 cm^{-3}) circumstellar medium. Implications of the circumstellar scattering environment for the spectropolarimetry are discussed, as are the effects of uncertain removal of interstellar polarization.
I present an overview of optical observations (mostly spectra) of Type II supernovae. SNe II are defined by the presence of hydrogen, and exhibit a very wide variety of properties. SNe II-L tend to show evidence of late-time interaction with circumstellar material. SNe IIn are distinguished by relatively narrow emission lines with little or no P-Cygni absorption component and (quite often) slowly declining light curves; they probably have unusually dense circumstellar gas with which the ejecta interact. Some SNe IIn, however, might not be genuine SNe, but rather are super-outbursts of luminous blue variables. The progenitors of SNe IIb contain only a low-mass skin of hydrogen; their spectra gradually evolve to resemble those of SNe Ib. Limited spectropolarimetry thus far indicates large asymmetries in the ejecta of SNe IIn, but much smaller ones in SNe II-P. There is intriguing, but still inconclusive, evidence that some peculiar SNe IIn might be associated with gamma-ray bursts. SNe II-P are useful for cosmological distance determinations with the Expanding Photosphere Method, which is independent of the Cepheid distance scale.
Accurate and speedy determination of transition structures (TSs) is essential for computational studies on reaction pathways, particularly when the process involves expensive electronic structure calculations. Many search algorithms require a good initial guess of the TS geometry, as well as a Hessian input that possesses a structure consistent with the desired saddle point. Among the double-ended interpolation methods for generation of the guess for the TS, the freezing string method (FSM) is proven to be far less expensive compared to its predecessor, the growing string method (GSM). In this paper, it is demonstrated that the efficiency of this technique can be improved further by replacing the conjugate gradient optimization step (FSM-CG) with a quasi-Newton line search coupled with a BFGS Hessian update (FSM-BFGS). A second crucial factor that affects the speed with which convergence to the TS is achieved is the quality and cost of the Hessian of the energy for the guessed TS. For electronic structure calculations, the cost of calculating an exact Hessian increases more rapidly with system size than the energy and gradient. Therefore, to sidestep calculation of the exact Hessian, an approximate Hessian is constructed, using the tangent direction and local curvature at the TS guess. It is demonstrated that the partitioned-rational function optimization algorithm for locating TSs with this approximate Hessian input performs at least as well as with an exact Hessian input in most test cases. The two techniques, FSM and approximate Hessian construction, therefore can significantly reduce costs associated with finding TSs.
