A three-way clusterwise multidimensional unfolding procedure for the spatial representation of context dependent preferences

Various deterministic and latent structure approaches for combining forms of multidimensional scaling and cluster analysis have been previously discussed. A new clusterwise three-way unfolding methodology for the analysis of two-way or three-way metric dominance/preference data is proposed. The purpose of this proposed methodology is to simultaneously estimate a joint space of stimuli and cluster ideal point representations, as well as the clusters themselves, such that the geometry underlying the clusterwise model renders some indication of the underlying structure in the data. In the three-way case, it is shown how multiple ideal points can represent preference change over contexts or situations. Partitions, overlapping clusters, stationary and context dependent preference representations are allowed. After a literature review of related methodological research, the technical details of the proposed three-way clusterwise spatial unfolding model are presented in terms of modeling context/situational dependent preferences (i.e., preferences for various stimuli collected over the same set of subjects over time, situation, etc.). The psychological basis for the models is provided in terms of the extensive behavioral decision theory and consumer psychology literature on contextual preferences and situational effects. An application to a data set exploring preferences for breakfast/snack food data over a number of different usage situations is then presented, followed by a discussion on future potential research directions.     

International Commission on Radiation Units and Measurements Report 78: Prescribing, Recording and Reporting Proton-beam Therapy

Proton therapy has recently garnered a great deal of attentionin the medical and scientific literature and at internationalconferences on radiation oncology. Hardly a month goes by withoutan announcement of a new initiative to install a proton therapycentre. The main physical advantage of proton therapy is itslower exit dose, which is afforded by the finite range of theprimary proton beam. The first and most important breakthroughin this field occurred in 1946, when Robert Wilson, a youngphysicist, proposed the rationale and basic methods for thetherapy and suggested engineering approaches to beam-shapingthat are still widely used today. By 1954, Tobias and colleaguesat the University of California had administered the first treatmentof a human being with proton beams; by the 1960s, the technologicalfoundation of proton therapy was complete, and routine clinicalproton therapy was under way. Despite this early     

Crosslinking of mixtures of diglycidylether of bisphenol‐A with 1,6‐dioxaspiro[4.4] nonan‐2,7‐dione initiated by tertiary amines: III. Effect of hydroxyl groups on network formation

BACKGROUND: Blends of epoxy resin oligomers, diglycidylether of bisphenol‐A (DGEBA), and a bislactone, 1,6‐dioxaspiro[4.4]nonan‐2,7‐dione (s(γBL)), were anionically copolymerized using two tertiary amines as anionic initiators. Their curing rheology and gelation behaviour were studied to provide a more comprehensive knowledge of the curing of these previously studied systems. RESULTS: The activation energy for gelation was found to be similar to that previously measured using differential scanning calorimetry and appeared to increase in the presence of the bislactone. The reaction rate during copolymerization of DGEBA with s(γBL) was slower than DGEBA homopolymerization alone because the alkoxide attack on the epoxide is faster than the reaction of the carboxylate ion and the epoxy group. The effect of the initiator type on the gel conversion was small and was presumably due to differences in the kinetic chain length caused by amine regeneration from the quaternary amine. For the same initiator and at a constant ratio of DGEBA/s(γBL), an increase in the hydroxyl concentration of the DGEBA oligomer raised the gel conversion. For a DGEBA oligomer with low hydroxyl levels, an increase in the concentration of s(γBL) increased the gel conversion; however, for a DGEBA oligomer with high hydroxyl levels, increasing s(γBL) concentration decreased the gel conversion. CONCLUSION: These results are interpreted in terms of the effect of initiation rate and chain transfer rate on the kinetic chain length. The glass transition temperature of the gel was found to be controlled by the fraction of the aliphatic s(γBL) and the amount of plasticizing sol in the matrix. Copyright © 2009 Society of Chemical Industry     

Products of pertechnetate radiolysis in highly alkaline solution: structure of TcO2 x xH2O

The chemistry of technetium in certain high-level nuclear waste (HLW) tanks at the Hanford Site complicates the treatment and vitrification of HLW. A major problem is the presence, in certain tanks, of unidentified, lower-valent technetium species, which are difficult to remove from the waste by current separation processes. Radiolytic reduction of TcO4- in alkaline solutions containing selected organic compounds, approximating the conditions in HLW, was investigated to determine the classes of compounds that can be formed under these conditions. Insoluble TcO2 x xH2O is the primary radiolysis product with the majority of organic compounds investigated, including citrate, dibutyl phosphate, and aminopolycarboxylates. X-ray absorption fine structure (XAFS) measurements show that TcO2 x xH2O has a one-dimensional chain structure consisting of edge-sharing TcO6 octahedra with bridging oxide and trans water ligands. When diols, such as ethylene glycol, are present, only soluble, Tc(IV) alkoxide compounds are produced. The XAFS and UV-visible spectra of these compounds provide evidence for a binuclear structure similar to (H2EDTA)2Tc2(mu-O)2. The properties of the Tc(IV) alkoxide complexes were determined and are consistent with those observed for the soluble, lower-valent technetium complexes that complicate the treatment of HLW at the Hanford site.     

Speed and safety effect of photo radar enforcement on a highway corridor in British Columbia

This study evaluates the effect of the photo radar program on traffic speed and collisions at photo radar (PRP) influence locations (PRP location) and interleaving non-PRP locations on the Vancouver Island portion of Highway 17 (Pat Bay Highway) in British Columbia (BC). Simple before-after comparison was used to summarize the speed effect while observational before- after method was employed to estimate the safety effect. To control for regression to the mean and time effect, Empirical Bayes (EB) method with comparison groups was employed in collision analysis. The study found a 2.8-km/h reduction in mean speed and a 0.5-km/h reduction in speed standard deviation at a monitoring site 2 km south of the treatment area. Corresponding to speed reduction. the study revealed a 14%+/-11% reduction in expected collisions at the PRP locations, a 19%+/-10% reduction at the non-PRP locations, and a 16%+/-7% reduction along the study corridor as a whole. No evidence was found for a localized effect in a 2-km range of the photo radar direct influence area, over and above those at the interleaving non-PRP locations. The results support the hypothesis of a distance spillover effect--that the program not only improved safety at the PRP locations, but along the entire enforcement corridor as well. It suggests that the unpredictable nature of the deployments lead drivers to modify their behavior along the length of the corridor because they could not discern 'safe' from 'unsafe' segments.     

Extending the solid-phase microextraction technique to high analyte concentrations: measurements and thermodynamic analysis

The solid-phase microextraction (SPME) technique has been used historically to quantify analytes present at the parts per million level. However, the nonintrusive nature of SPME lends itself to other applications involving analytes at higher concentration. In the current work, the possibility of using the SPME technique to measure concentrated gaseous samples was examined. Pentane concentrations between 0 and 100% saturation were studied, over a temperature range of 20-45 degrees C. The results showed that, up to a critical mole fraction in the solid phase, the concentrations of pentane in the polymeric extracting solid and vapor phases were related by a constant, equal to Henry's constant. The temperature dependence of Henry's constant was shown to follow the predicted trend with temperature, as determined from rigorous thermodynamic calculations. Above the pentane concentration in the polymeric phase, the response deviated from linearity. The nonideality was captured in an activity coefficient. An activity coefficient model developed to describe the nonideality was found to be a function of the swollen volume of the SPME polymer phase. The results indicate that the SPME technique can be applied to high analyte concentrations, although difficulties may be encountered when multiple analytes are absorbed.     

Efficacy of a tailored tobacco control program on long-term use in a population of U.S. Military troops.

The authors evaluated the effect of a brief tailored smoking control intervention delivered during basic military training on tobacco use in a population of military personnel (N = 33,215). Participants were randomized to either a tobacco use intervention (smoking cessation, smokeless tobacco use cessation, or prevention depending on tobacco use history) or a health education control condition. Results indicated that smokers who received intervention were 1.16 (95% confidence interval [CI] = 1.04, 1.30) times (7-day point prevalence) and 1.23 (95% CI = 1.07, 1.41) times (continuous abstinence) more likely to be abstinent than controls from smoking cigarettes at the 1-year follow-up (p p     

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…