Conflicting Beliefs: A Story of a Chemistry Teacher's Struggle with Change

One teacher's struggle to develop and implement a curriculum focused on student understanding of chemistry is explored in this case study of a high school chemistry teacher. Conflicting beliefs about her roles as a teacher in the classroom and her professional responsibilities are addressed. Three primary conflicts that emerged from data collected over a two year period include, (a) conflicts between state curriculum mandates and individual student understanding; (b) conflicts between theoretical and applicable chemistry content knowledge, and (c) conflicts between the students' goals and the teachers' goals for the course. The impact of the research process on the teacher's change process included reconceptualization of constraints and development of confidence in her professional judgment. The case study provides insights into contextual problems teachers face as they attempt to change practices.     

13C n.m.r. studies of some phenanthrene and fluorene derivatives

The ¹H and ¹³C spectra of fluorene, fluorenone, phenanthrene and their 4-methyl and 4,5-dimethyl derivatives have been examined. To complete the analyses for fluorenone and 4-methylfluorenone, ¹H spectra were recorded at 270 MHz. The results from the ¹H spectra permitted unequivocal assignments for the protonated aryl carbons by selective proton decoupling. A consistent set of assignments for the quaternary carbons was obtained through consideration of the dominant relaxation processes operative at these centres. This series of compounds was examined to investigate the shielding effects produced by the close approach of methyl groups separated by five bonds for comparison with the contrasting trends found for methyl carbons separated by three and four bonds. The results indicate that the relative orientation of the methyl groups is an extremely critical factor governing their shieldings and those of neighboring centres.     

Spectroscopic characterization of some chlorinated tricyclic hydrocarbons of the C10 series: Chlordanes,chlordenes and nonachlors

Carbon-13 and proton nuclear magnetic resonance (n.m.r.) spectra of ten chlorinated hydrocarbons, which are components of technical chlordane and one chlordane metabolite, were examined. For chlordene, dichlorochlordene, cis- and trans-nonachlor, and cis- and trans-chlordane, whose chemical structures are well-established, the relationships between the n.m.r. parameters and these structures were investigated. The results allow confirmation of proposed structures for α-, β-, and γ-chlordene. A structure, corresponding to 2,4,5,5,6,7,8,8-octachloro-2,3,3a,4,5,7a-hexahydro-1,4-methano-1-H-indene, is proposed for another chlordane component, previously known only as Compound K.     

Reactions of dichlorobis(ditertiaryphosphine)-ruthenium(II) with carbon monoxide: Preparation of dicarbonylbis(ditertiaryphosphine) ruthenium(II) cations

Reactions of RuCl₂(L-L)₂ (L-L = dppm or dppe) with CO and silver salts of non coordinating anions produce [Ru(CO)₂(L-L)₂]X₂ which, once formed, are stable to CO loss. However, the fluxional five coordinate intermediates [Ru(Cl) (L-L)₂]X, which in some cases may contain ion pairs, are sufficiently electrophilic to abstract fluoride ion from [BF₄]^? or to coordinate other ions in solution such as [O₂PF₂]^? formed by hydrolysis of [PF₆]^?. A series of complexes of general formula [Ru(CO)₂ (dppm)₂AgY]X₂ may also be isolated and are shown to contain a dppm ligand bridging ruthenium and silver, the bond between which is reversibly cleaved by nitromethane on the nmr timescale.     

Multiscale agent‐based consumer market modeling

Consumer markets have been studied in great depth, and many techniques have been used to represent them. These have included regression‐based models, logit models, and theoretical market‐level models, such as the NBD‐Dirichlet approach. Although many important contributions and insights have resulted from studies that relied on these models, there is still a need for a model that could more holistically represent the interdependencies of the decisions made by consumers, retailers, and manufacturers. When the need is for a model that could be used repeatedly over time to support decisions in an industrial setting, it is particularly critical. Although some existing methods can, in principle, represent such complex interdependencies, their capabilities might be outstripped if they had to be used for industrial applications, because of the details this type of modeling requires. However, a complementary method—agent‐based modeling—shows promise for addressing these issues. Agent‐based models use business‐driven rules for individuals (e.g., individual consumer rules for buying items, individual retailer rules for stocking items, or individual firm rules for advertizing items) to determine holistic, system‐level outcomes (e.g., to determine if brand X's market share is increasing). We applied agent‐based modeling to develop a multi‐scale consumer market model. We then conducted calibration, verification, and validation tests of this model. The model was successfully applied by Procter & Gamble to several challenging business problems. In these situations, it directly influenced managerial decision making and produced substantial cost savings. © 2010 Wiley Periodicals, Inc. Complexity, 2010     

Repeated significance tests with biased coin allocation schemes

Summary Suppose that the responses to two treatments are from a single parameter exponential family. Treatments are allocated sequentially using a biased coin design (that is, the probability that the (n+1)-st subject is assigned to treatment A is a function of the proportion of the first n subjects that have been assigned to treatment A). Asymptotic error probabilities are found for a repeated significance test of the hypothesis that the two treatments elicit the same response.