American University in Cairo

About: American University in Cairo is a education organization based out in Cairo, Egypt. It is known for research contribution in the topics: Population & Context (language use). The organization has 2472 authors who have published 5339 publications receiving 73741 citations.

Aerobic methanotrophic communities at the Red Sea brine-seawater interface.

Abstract: The central rift of the Red Sea contains 25 brine pools with different physicochemical conditions, dictating the diversity and abundance of the microbial community. Three of these pools, the Atlantis II, Kebrit and Discovery Deeps, are uniquely characterized by a high concentration of hydrocarbons. The brine-seawater interface, described as an anoxic-oxic (brine-seawater) boundary, is characterized by a high methane concentration, thus favoring aerobic methane oxidation. The current study analyzed the aerobic free–living methane-oxidizing bacterial communities that potentially contribute to methane oxidation at the brine-seawater interfaces of the three aforementioned brine pools, using metagenomic pyrosequencing, 16S rRNA pyrotags and pmoA library constructs. The sequencing of 16S rRNA pyrotags revealed that these interfaces are characterized by high microbial community diversity. Signatures of aerobic methane-oxidizing bacteria were detected in the Atlantis II Interface (ATII-I) and the Kebrit Deep Upper (KB-U) and Lower (KB-L) brine-seawater interfaces. Through phylogenetic analysis of pmoA, we further demonstrated that the ATII-I aerobic methanotroph community is highly diverse. We propose four ATII-I pmoA clusters. Most importantly, cluster 2 groups with marine methane seep methanotrophs, and cluster 4 represent a unique lineage of an uncultured bacterium with divergent alkane monooxygenases. Moreover, non-metric multidimensional scaling (NMDS) based on the ordination of putative enzymes involved in methane metabolism showed that the Kebrit interface layers were distinct from the ATII-I and DD-I brine-seawater interfaces.

Hybrid Plasmonic Modulators and Filters Based on Electromagnetically Induced Transparency

Abstract: A hybrid plasmonic modulator based on microdisk resonators enhanced with electro-optic polymers is presented. Modulation is achieved by dynamically controlling an electromagnetically induced transparency window using a push–pull driving configuration. The proposed device combines small footprint, high modulation depths, low insertion losses, and low power consumption. By properly selecting the voltage values and the microdisk radii, modulation at different wavelengths and tunable spectral filtering are achieved.

Teachers' Conceptions of Assessment: A Global Phenomenon or a Global Localism

Abstract: How teachers conceive of the nature and purpose of assessment matters to the implementation of classroom assessment and the preparation of students for high-stakes external examinations or qualifications. It is highly likely that teacher beliefs arise from the historical, cultural, social, and policy contexts within which teachers operate. Hence, it may be that there is not a globally homogeneous construct of teacher conceptions of assessment. Instead, it is possible that a statistical model of teacher conceptions of assessment will always be a local expression. Thus, the objective of this study was to determine whether any of the published models of teacher assessment conceptions could be generalised across data sets from multiple jurisdictions. Research originating in New Zealand with the Teacher Conceptions of Assessment self-report inventory has been replicated in multiple locations and languages (i.e., English in New Zealand, Queensland, Hong Kong, and India; Greek in Cyprus; Arabic in Egypt; Spanish in Spain, Ecuador) and at different levels of instructional contexts (Primary, Secondary, Senior Secondary, and Teacher Education). This study conducts secondary data analyses in which eight previously published models of teacher conceptions of assessment were systematically compared across 11 available data sets. Nested multi-group confirmatory factor analysis (using Amos v25) was carried out to establish sequentially configural, metric, and scalar equivalence between models. Results indicate that only one model (i.e., India) had configural invariance across all 11 data sets and this did not achieve metric equivalence. These results indicate that while the inventory can be used cross-culturally after localized adaptations, there is indeed no single global model. Context, culture, and local factors shape teacher conceptions of assessment.