731 research outputs found
A Petrological and Geochemical Study of the O.K. Copper-Molybdenum Deposit Beaver County, Utah.
Nonaqueous slip casting of YBa2Cu3O(7-x) superconductive ceramics
This study investigates the slip casting of YBa2Cu3O(7-x) powders using nonaqueous carrier liquids and fired ceramic molds. The parameters of the process examined here include the rheological properties of YBa2Cu3O(7-x) powder dispersed in various solvent/dispersant systems, the combination of nonaqueous slips with fired ceramic molds to form the superconductive ceramics, the process-property relationships using a four-factor factorial experiment, and the applicability of magnetic fields to align the YBa2Cu3O(7-x) grains during the casting process
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Evaluating technology-based strategies for enhancing motivation in mathematics
Background, context, and purpose of study: During the middle school years, students frequently show significant declines in motivation toward school in general and mathematics in particular. One way in which researchers have sought to spark students’ interests and build their sense of competence in mathematics and in STEM more generally is through the use of technology. Yet evidence regarding the motivational effectiveness of this approach is mixed. Here we evaluate the impact of three brief technology-based activities on students’ short-term motivation in math. 16,789 5th to 8th grade students and their teachers in one large school district were randomly assigned to three different technology-based activities, each representing a different framework for motivation and engagement and all designed around an exemplary lesson related to algebraic reasoning. We investigated the relationship between specific technology-based activities that embody various motivational constructs and students’ engagement in mathematics and perceived competence in pursuing STEM careers.
Article available under a Creative Commons Attribution 4.0 License
Bostonia: The Boston University Alumni Magazine. Volume 9
Founded in 1900, Bostonia magazine is Boston University's main alumni publication, which covers alumni and student life, as well as university activities, events, and programs
Split String Formalism and the Closed String Vacuum
The split string formalism offers a simple template upon which we can build
many generalizations of Schnabl's analytic solution of open string field
theory. In this paper we consider two such generalizations: one which replaces
the wedge state by an arbitrary function of wedge states, and another which
generalizes the solution to conformal frames other than the sliver.Comment: 25 pages, 11 figures. Figures and discussion in Section 4 improve
A Simple Analytic Solution for Tachyon Condensation
In this paper we present a new and simple analytic solution for tachyon
condensation in open bosonic string field theory. Unlike the B_0 gauge
solution, which requires a carefully regulated discrete sum of wedge states
subtracted against a mysterious "phantom" counter term, this new solution
involves a continuous integral of wedge states, and no regularization or
phantom term is necessary. Moreover, we can evaluate the action and prove Sen's
conjecture in a mere few lines of calculation.Comment: 44 pages
Alite calcium sulfoaluminate cement: chemistry and thermodynamics
Calcium sulfoaluminate (CA) cements can combine the favourable characteristics of Portland cement (PC) with those of CA clinkers. The first is a thermodynamic study demonstrating that the production of a-CA clinker can be readily produced in a standard process by controlling the oxygen and sulfur dioxide fugacity in the atmosphere. This allows for the stabilisation of ye’elimite to the higher temperatures required for alite stability. The second result establishes that when using fluorine to mineralise a-C$A clinker production, the iron content in the clinker is also an important variable. Although the exact mechanism of alite stabilisation is not known, it is shown that alite formation increases with the combination of calcium fluoride and iron (III) oxide in the mix
Os partidos dentro e fora do poder: a judicialização como resultado contingente da estratégia política
Dynamics of Macrophage Trogocytosis of Rituximab-Coated B Cells
Macrophages can remove antigen from the surface of antibody-coated cells by a process termed trogocytosis. Using live cell microscopy and flow cytometry, we investigated the dynamics of trogocytosis by RAW264.7 macrophages of Ramos B cells opsonized with the anti-CD20 monoclonal antibody rituximab. Spontaneous and reversible formation of uropods was observed on Ramos cells, and these showed a strong enrichment in rituximab binding. RAW-Ramos conjugate interfaces were highly enriched in rituximab, and transfer of rituximab to the RAW cells in submicron-sized puncta occurred shortly after cell contact. Membrane from the target cells was concomitantly transferred along with rituximab to a variable extent. We established a flow cytometry-based approach to follow the kinetics of transfer and internalization of rituximab. Disruption of actin polymerization nearly eliminated transfer, while blocking phosphatidylinositol 3-kinase activity only resulted in a delay in its acquisition. Inhibition of Src family kinase activity both slowed acquisition and reduced the extent of trogocytosis. The effects of inhibiting these kinases are likely due to their role in efficient formation of cell-cell conjugates. Selective pre-treatment of Ramos cells with phenylarsine oxide blocked uropod formation, reduced enrichment of rituximab at cell-cell interfaces, and reduced the efficiency of trogocytic transfer of rituximab. Our findings highlight that dynamic changes in target cell shape and surface distribution of antigen may significantly influence the progression and extent of trogocytosis. Understanding the mechanistic determinants of macrophage trogocytosis will be important for optimal design of antibody therapies
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