853 research outputs found

    Measures of distance from a randomly located point to neighboring lattice points for rectangular and hexagonal point lattices Technical report no. 3

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    Probability density function and distribution function of distance from random point in polygon to the nearest corner in lattic

    Abstracts of unpublished theses on the gifted child found in the School of Education Library at Boston University which were not included in the Gaffney thesis of 1958

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    Thesis (Ed.M.)--Boston UniversityAndrews, Charles Herbert. "A Survey of Curriculum Materials of Value for the Teaching of Gifted Elementary School Children in the Language Arts Area." Unpublished Ed. M. Thesis, Boston University School of Education, 1957. Problem. To determine the curriculum materials which should be included in an elementary school classroom devoted to the maximal effective teaching of gifted children in the language arts area. [TRUNCATED

    A probability law obtained by compounding the Poisson and half-normal probability laws Technical report no. 4

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    Discrete probability law obtained by assuming Poisson variable parameter is distributed according to half-normal probability la

    Some comments on certain technical aspects on geographic information systems Technical report no. 2

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    Two-dimensional machine language and spatial statistics for design and development of geographic information system

    The Grey Areas : Ways Teachers Make Meaning of and Describe Enacting Professional Ethics

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    This dissertation explored the experiences of 12 classroom teachers making meaning of their ethical practice in K–12 schools. The study uncovered how these teachers identify and problematize ethical issues as they relate to their practice. Through semi-structured interviewing, participants’ experiences around ethical practice were recorded and analyzed using Gilligan’s (1982) Listening Guide. The data collected provides insight into how these teachers make meaning of their practices, a process characterized by a complex interplay amongst personal and professional beliefs around caring and protecting students and their needs, a sense of responsibility as employees to adhere to district and school policies, an obligation to uphold the standards of the teaching profession, and the contextualized pressures and expectations of their specific teaching communities. Overall, the study describes the ways in which participants make meaning of their ethical practice amidst the increasing demands of the standards movement and accountability-based reforms that have contextualized teachers lived daily experiences. In particular, in sharing their stories, this study brings to light many instances of K–12 teachers resisting these demands imposed in order to best support the learning and long-term development of their students. I aim to provide a nuanced view into how these teachers remain committed to carrying out what is in students’ best interests. Their efforts creatively and quietly resisting and negotiating the structural and human pressures imposed on them are heartwarming at times. Similarly, their struggles, anxieties, disappointments, distress, and fatigue are heartbreaking but offer a glimpse into how these educators are enacting ethical practice despite the challenging contexts of schools today

    Analytical Results for the Statistical Distribution Related to Memoryless Deterministic Tourist Walk: Dimensionality Effect and Mean Field Models

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    Consider a medium characterized by N points whose coordinates are randomly generated by a uniform distribution along the edges of a unitary d-dimensional hypercube. A walker leaves from each point of this disordered medium and moves according to the deterministic rule to go to the nearest point which has not been visited in the preceding \mu steps (deterministic tourist walk). Each trajectory generated by this dynamics has an initial non-periodic part of t steps (transient) and a final periodic part of p steps (attractor). The neighborhood rank probabilities are parameterized by the normalized incomplete beta function I_d = I_{1/4}[1/2,(d+1)/2]. The joint distribution S_{\mu,d}^{(N)}(t,p) is relevant, and the marginal distributions previously studied are particular cases. We show that, for the memory-less deterministic tourist walk in the euclidean space, this distribution is: S_{1,d}^{(\infty)}(t,p) = [\Gamma(1+I_d^{-1}) (t+I_d^{-1})/\Gamma(t+p+I_d^{-1})] \delta_{p,2}, where t=0,1,2,...,\infty, \Gamma(z) is the gamma function and \delta_{i,j} is the Kronecker's delta. The mean field models are random link model, which corresponds to d \to \infty, and random map model which, even for \mu = 0, presents non-trivial cycle distribution [S_{0,rm}^{(N)}(p) \propto p^{-1}]: S_{0,rm}^{(N)}(t,p) = \Gamma(N)/\{\Gamma[N+1-(t+p)]N^{t+p}\}. The fundamental quantities are the number of explored points n_e=t+p and I_d. Although the obtained distributions are simple, they do not follow straightforwardly and they have been validated by numerical experiments.Comment: 9 pages and 4 figure

    Revising upper-ocean sulfur dynamics near Bermuda : new lessons from 3 years of concentration and rate measurements

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    © The Author(s), 2015. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Environmental Chemistry 13 (2016): 302-313, doi:10.1071/EN15045.Oceanic biogeochemical cycling of dimethylsulfide (DMS), and its precursor dimethylsulfoniopropionate (DMSP), has gained considerable attention over the past three decades because of the potential role of DMS in climate mediation. Here we report 3 years of monthly vertical profiles of organic sulfur cycle concentrations (DMS, particulate DMSP (DMSPp) and dissolved DMSP (DMSPd)) and rates (DMSPd consumption, biological DMS consumption and DMS photolysis) from the Bermuda Atlantic Time-series Study (BATS) site taken between 2005 and 2008. Concentrations confirm the summer paradox with mixed layer DMS peaking ~90 days after peak DMSPp and ~50 days after peak DMSPp : Chl. A small decline in mixed layer DMS was observed relative to those measured during a previous study at BATS (1992–1994), potentially driven by long-term climate shifts at the site. On average, DMS cycling occurred on longer timescales than DMSPd (0.43 ± 0.35 v. 1.39 ± 0.76 day–1) with DMSPd consumption rates remaining elevated throughout the year despite significant seasonal variability in the bacterial DMSP degrader community. DMSPp was estimated to account for 4–5 % of mixed layer primary production and turned over at a significantly slower rate (~0.2 day–1). Photolysis drove DMS loss in the mixed layer during the summer, whereas biological consumption of DMS was the dominant loss process in the winter and at depth. These findings offer new insight into the underlying mechanisms driving DMS(P) cycling in the oligotrophic ocean, provide an extended dataset for future model evaluation and hypothesis testing and highlight the need for a reexamination of past modelling results and conclusions drawn from data collected with old methodologies.The authors acknowledge funding from the National Science Foundation (NSF) (OCE-0425166) and the Center for Microbial Oceanography Research and Education (CMORE) a NSF Science and Technology Center (EF-0424599)

    Environmental, biochemical and genetic drivers of DMSP degradation and DMS production in the Sargasso Sea

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    Author Posting. © The Author(s), 2011. This is the author's version of the work. It is posted here by permission of John Wiley & Sons for personal use, not for redistribution. The definitive version was published in Environmental Microbiology 14 (2012): 1210-1223, doi:10.1111/j.1462-2920.2012.02700.x.Dimethylsulfide (DMS) is a climatically relevant trace gas produced and cycled by the surface ocean food web. Mechanisms driving intraannual variability in DMS production and dimethylsulfoniopropionate (DMSP) degradation in open-ocean, oligotrophic regions were investigated during a 10 month time-series at the Bermuda Atlantic Time-series Study site in the Sargasso Sea. Abundance and transcription of bacterial DMSP degradation genes, DMSP lyase enzyme activity, and DMS and DMSP concentrations, consumption rates, and production rates were quantified over time and depth. This interdisciplinary dataset was used to test current hypotheses of the role of light and carbon supply in regulating upper-ocean sulfur cycling. Findings supported UV-A dependent phytoplankton DMS production. Bacterial DMSP degraders may also contribute significantly to DMS production when temperatures are elevated and UV-A dose is moderate, but may favor DMSP demethylation under low UV-A doses. Three groups of bacterial DMSP degraders with distinct intraannual variability were identified and niche differentiation was indicated. The combination of genetic and biochemical data suggest a modified ‘bacterial switch’ hypothesis where the prevalence of different bacterial DMSP degradation pathways is regulated by a complex set of factors including carbon supply, temperature, and UV-A dose.This research was funded by National Science Foundation (NSF) grants OCE- 0525928, OCE-072417, and OCE-042516. Additional funding was provided by the NSF Center for Microbial Oceanography Research and Education (CMORE), the Gordon and Betty Moore Foundation, the Scurlock Fund, the Ocean Ventures Fund, a National Defense Science and Engineering Graduate Fellowship, and an Environmental Protection Agency STAR Graduate Fellowship
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