Braid groups of imprimitive complex reflection groups

We obtain new presentations for the imprimitive complex reflection groups of type $(de,e,r)$ and their braid groups $B(de,e,r)$ for $d,r \ge 2$. Diagrams for these presentations are proposed. The presentations have much in common with Coxeter presentations of real reflection groups. They are positive and homogeneous, and give rise to quasi-Garside structures. Diagram automorphisms correspond to group automorphisms. The new presentation shows how the braid group $B(de,e,r)$ is a semidirect product of the braid group of affine type $\widetilde A_{r-1}$ and an infinite cyclic group. Elements of $B(de,e,r)$ are visualized as geometric braids on $r+1$ strings whose first string is pure and whose winding number is a multiple of $e$. We classify periodic elements, and show that the roots are unique up to conjugacy and that the braid group $B(de,e,r)$ is strongly translation discrete.Comment: published versio

Estimating exposure response functions using ambient pollution concentrations

This paper presents an approach to estimating the health effects of an environmental hazard. The approach is general in nature, but is applied here to the case of air pollution. It uses a computer model involving ambient pollution and temperature input to simulate the exposures experienced by individuals in an urban area, while incorporating the mechanisms that determine exposures. The output from the model comprises a set of daily exposures for a sample of individuals from the population of interest. These daily exposures are approximated by parametric distributions so that the predictive exposure distribution of a randomly selected individual can be generated. These distributions are then incorporated into a hierarchical Bayesian framework (with inference using Markov chain Monte Carlo simulation) in order to examine the relationship between short-term changes in exposures and health outcomes, while making allowance for long-term trends, seasonality, the effect of potential confounders and the possibility of ecological bias. The paper applies this approach to particulate pollution (PM10) and respiratory mortality counts for seniors in greater London (≥65 years) during 1997. Within this substantive epidemiological study, the effects on health of ambient concentrations and (estimated) personal exposures are compared. The proposed model incorporates within day (or between individual) variability in personal exposures, which is compared to the more traditional approach of assuming a single pollution level applies to the entire population for each day. Effects were estimated using single lags and distributed lag models, with the highest relative risk, RR=1.02 (1.01–1.04), being associated with a lag of two days ambient concentrations of PM10. Individual exposures to PM10 for this group (seniors) were lower than the measured ambient concentrations with the corresponding risk, RR=1.05 (1.01–1.09), being higher than would be suggested by the traditional approach using ambient concentrations

Assessment of the Intake and Knowledge of Folate/Folic Acid Among UNH Students

There are 3,000 U.S. pregnancies affected by spina bifida and anencephaly annually. If women consume adequate amounts of folic acid (400 mcg/day) one month before pregnancy and through the first trimester, then the risk of their infant developing a neural tube defect (NTD) is reduced by 50-70%. However, approximately 50% of pregnancies are unplanned, with some of the highest rates among 18-24 year olds. The purpose of this study was to evaluate the knowledge source, knowledge level, and intake of folic acid among college-aged students. Qualtrics surveys from 96 subjects (87.5% female, aged 18-24) were used for analysis. In the female sample, 16% were taking a multivitamin containing folic acid and 7% a folic acid supplement. Three questions assessed the sample’s level of folic acid knowledge. Seventy-six percent knew adequate amounts are needed to prevent NTDs, 71% knew it is most important to start consuming it before pregnancy, and 54% answered at least half of the correct food sources. There were 19 females who took an introductory nutrition course, and 63.2% correctly answered NTDs, before pregnancy, and at least half the food sources. Subjects who got folic acid knowledge from a college course were significantly more likely to answer the three questions correctly compared to those who never received information on the vitamin. Findings suggested that among college students, the best source of information about folic acid is college courses. Future research may study the correlation between folic acid knowledge and knowledge source among a larger, more diverse college population

Building spelling power: word analysis lessons for grade 2.

Thesis (Ed.M.)--Boston Universit

The construction and administration of a questionnaire on children's reaction to educational television

Thesis (Ed.M.)--Boston University N.B.: Missing pages 93-111. Possibly misnumbered

Dynamics of methane ebullition from a peat monolith revealed from a dynamic flux chamber system

Methane (CH4) ebullition in northern peatlands is poorly quantified in part due to its high spatiotemporal variability. In this study, a dynamic flux chamber (DFC) system was used to continuously measure CH4 fluxes from a monolith of near‐surface Sphagnum peat at the laboratory scale to understand the complex behavior of CH4 ebullition. Coincident transmission ground penetrating radar measurements of gas content were also acquired at three depths within the monolith. A graphical method was developed to separate diffusion, steady ebullition, and episodic ebullition fluxes from the total CH4 flux recorded and to identify the timing and CH4 content of individual ebullition events. The results show that the application of the DFC had minimal disturbance on air‐peat CH4 exchange and estimated ebullition fluxes were not sensitive to the uncertainties associated with the graphical model. Steady and episodic ebullition fluxes were estimated to be averagely 36 ± 24% and 38 ± 24% of the total fluxes over the study period, respectively. The coupling between episodic CH4 ebullition and gas content within the three layers supports the existence of a threshold gas content regulating CH4 ebullition. However, the threshold at which active ebullition commenced varied between peat layers with a larger threshold (0.14 m3 m−3) observed in the deeper layers, suggesting that the peat physical structure controls gas bubble dynamics in peat. Temperature variation (23°C to 27°C) was likely only responsible for small episodic ebullition events from the upper peat layer, while large ebullition events from the deeper layers were most likely triggered by drops in atmospheric pressure

Role of the fast kinetics of pyroglutamate-modified amyloid-β oligomers in membrane binding and membrane permeability.

Membrane permeability to ions and small molecules is believed to be a critical step in the pathology of Alzheimer's disease (AD). Interactions of oligomers formed by amyloid-β (Aβ) peptides with the plasma cell membrane are believed to play a fundamental role in the processes leading to membrane permeability. Among the family of Aβs, pyroglutamate (pE)-modified Aβ peptides constitute the most abundant oligomeric species in the brains of AD patients. Although membrane permeability mechanisms have been studied for full-length Aβ1-40/42 peptides, these have not been sufficiently characterized for the more abundant AβpE3-42 fragment. Here we have compared the adsorbed and membrane-inserted oligomeric species of AβpE3-42 and Aβ1-42 peptides. We find lower concentrations and larger dimensions for both species of membrane-associated AβpE3-42 oligomers. The larger dimensions are attributed to the faster self-assembly kinetics of AβpE3-42, and the lower concentrations are attributed to weaker interactions with zwitterionic lipid headgroups. While adsorbed oligomers produced little or no significant membrane structural damage, increased membrane permeabilization to ionic species is understood in terms of enlarged membrane-inserted oligomers. Membrane-inserted AβpE3-42 oligomers were also found to modify the mechanical properties of the membrane. Taken together, our results suggest that membrane-inserted oligomers are the primary species responsible for membrane permeability

Social Reformers and Regulation: The Prohibition of Cigarettes in the U.S. and Canada

The apogee of anti-smoking legislation in North America was reached early in the last century. In 1903, the Canadian Parliament passed a resolution prohibiting the manufacture, importation, and sale of cigarettes. Around the same time, fifteen states in the United States banned the sale of cigarettes and thirty-five states considered prohibitory legislation. In both the United States and Canada, prohibition was part of a broad political, economic, and social coalition termed the Progressive Movement. Cigarette prohibition was special interest regulation, though not of the usual narrow neoclassical genre; it was the means by which a group of crusaders sought to alter the behavior of a much larger segment of the population. The opponents of cigarette regulation were cigarette smokers and the more organized cigarette lobby. An active Progressive Movement was the necessary condition for generating interest in prohibition, while the anti-prohibition forces played a more significant role later in the legislative process. The moral reformers' succeeded when they faced little opposition because few constituents smoked and/or no jobs were at stake because there was no cigarette industry. In other words, reform is easy when you are preaching to the converted.

Corporate Governance in Emerging Markets

The turning to the XXI century has been marked by reforms in corporate governance practices around the world. Whether due to shocks caused by the economic crisis in East Asia, Russia and Latin America, or by financial scandals in the United States and Europe, the fact is that the way of doing business has changed in terms of demands for greater corporate transparency and accountability, shifts in control of ownership, empowerment of new types of owners and so on. Consequently, countries and firms have adapted their corporate governance policies and practices to this new governance environment. In this chapter, we discuss the foundation of corporate governance, that is, corporate ownership. In particular, we explore the current patterns of the ownership structure of publicly listed firms in six emerging countries. To do so, we have collected firm ownership data for listed firms in Brazil, Chile, South Korea, Czech Republic, Hungary, and Poland during the first decade of the XXI century, and we compare our data with existing ownership research of these countries in the late 1990s. We conclude that although concentration of corporate shareholdings continues to be a common denominator among these emerging countries, the processes and structures controlling firms across countries is remarkably different. For instance, the privatization process in the 1990s, in spite of having different motivations and goals in Latin American and Eastern Europe shaped much of the corporate ownership transformations. Our chapter offers a comparative analysis of the corporate ownership changes in emerging markets.