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Largo, MD, United States

Sinex S.A.,Prince Georges Community College | Halpern J.B.,Howard University
Materials Research Society Symposium Proceedings

We describe how students explore materials science concepts using animated interactive spreadsheets. An engaging pedagogy is created in the classroom using spreadsheets in a way that initially camouflages mathematical complexity, which can later be revealed and taught. Use of off-the-shelf spreadsheet software, including freeware makes these spreadsheets universally available. © 2011 Materials Research Society. Source

Sinex S.A.,Prince Georges Community College | Halpern J.B.,Howard University
Materials Research Society Symposium Proceedings

Many materials science concepts can be developed into animated, interactive spreadsheets to create engaging discovery learning tools. These Excel spreadsheets do not require programming expertise. Learning how to create and use these didactically useful spreadsheets is simple and new examples can be quickly created by instructors. © 2010 Materials Research Society. Source

Sahu S.N.,U.S. Food and Drug Administration | Sahu S.N.,Oak Ridge Institute for Science and Education | Anriany Y.,Prince Georges Community College | Grim C.J.,U.S. Food and Drug Administration | And 5 more authors.

Salmonella enterica serover Typhimurium definitive phage type DT104, resistant to multiple antibiotics, is one of the most widespread Salmonella species in human infection worldwide. Although several cohort studies indicate that DT104 carrying the multidrug resistance (MDR) locus on salmonella genomic island 1 is a possible hyper-virulent strain compared to DT104 strains without MDR, or other Salmonella enterica serotypes, existing experimental evidence regarding virulence properties associated with the MDR region is controversial. To address this question, we constructed an isogenic MDR deletion ({increment}MDR) mutant strain of DT104, SNS12, by allelic exchange and used Caenorhabditis elegans as a host model to assess differences in virulence between these two strains. SNS12 exhibited decreased virulence in C. elegans, and we observed increased colonization and proliferation of the intestine of C. elegans by DT104. The immune response against MDR-carrying DT104 appears to function through a non-canonical Unfolded Protein Response (UPR) pathway, namely prion-like-(QN-rich)-domain-bearing protein pathway (PQN), in a ced-1 dependent manner in C. elegans. Further, we also demonstrate that genes of the PQN pathway and antimicrobial peptide gene abf-2, are expressed at higher transcriptional levels in worms immediately following exposure to DT104, in comparison with worms exposed to SNS12. Altogether, our results suggest that the MDR region of Salmonella Typhimurium DT104 has a direct role in virulence against Caenorhabditis elegans. Source

Silverman S.E.,Prince Georges Community College
Pennsylvania Geographer

Topical geography employs a multiplicity of methods in the depiction of both natural and cultural landscapes. One technique is to investigate the transformation of human attributes of a landscape as it evolves over a prolong period of time. A geographic synthesis emerges when attributes of economics, sociology and political ideology are united to illuminate cultural persistence, as well as transformation, as amplified by what can be observable in the landscape. Maryland's Catoctin Valley can be considered a subregion within Appalachia. In early 18th century it was part of the Trans-Appalachian Frontier as English and German settlers progressed towards the Shenandoah and Ohio Valleys. The valley reflects a spatial transformation brought on by turnpikes and a great canal that was, subsequently, replaced by both steam and electric railroads. Now the suburban frontier of the Washington's metropolis is intruding consequent to interstate construction, but this intrusion has not compromised historical vestiges of America's past three hundred years as apparent in the Valley's present landscape. Agrarianism, industrialization and suburban development, in the Catoctin Valley, reflect well the study of landscape evolution in both spatial and temporal contexts. Source

Juarrero A.,Georgetown University | Juarrero A.,University of Miami | Juarrero A.,Prince Georges Community College
Progress in Biophysics and Molecular Biology

The role of context-sensitive constraints - first as enablers of complexification and subsequently as regulators that maintain the integrity of self-organized, coherent wholes - has only recently begun to be examined. Conceptualizing such organizational constraints in terms of the operations of far from equilibrium, nonlinear dynamic processes rekindles old metaphysical discussions concerning primary and secondary relations, emergence, causality, and the logic of explanation. In particular, far-from-equilibrium processes allow us to rethink how parts-to-whole and whole-to-parts - so-called "mereological"- relationships are constituted. A renewed understanding of recursive feedback and the role context-dependence plays in generating the boundary conditions and the internal organization of complex adaptive systems in turn allows us to redescribe formal and final cause in such a way as to provide a meaningful sense of heretofore seemingly intractable philosophical problems such as autonomy, self-determination, and agency. © 2015 . Source

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