Coherent ultrafast lattice-directed reaction dynamics of triiodide anion photodissociation

Solid-state reactions are influenced by the spatial arrangement of the reactants and the electrostatic environment of the lattice, which may enable lattice-directed chemical dynamics. Unlike the caging imposed by an inert matrix, an active lattice participates in the reaction, however, little evidence of such lattice participation has been gathered on ultrafast timescales due to the irreversibility of solid-state chemical systems. Here, by lowering the temperature to 80 K, we have been able to study the dissociative photochemistry of the triiodide anion (I₃−) in single-crystal tetra-n-butylammonium triiodide using broadband transient absorption spectroscopy. We identified the coherently formed tetraiodide radical anion (I₄•−) as a reaction intermediate. Its delayed appearance after that of the primary photoproduct, diiodide radical I₂•−, indicates that I₄•− was formed via a secondary reaction between a dissociated iodine radical (I^•) and an adjacent I₃−. This chemistry occurs as a result of the intermolecular interaction determined by the crystalline arrangement and is in stark contrast with previous solution studies

Multiple novel prostate cancer susceptibility signals identified by fine-mapping of known risk loci among Europeans

Genome-wide association studies (GWAS) have identified numerous common prostate cancer (PrCa) susceptibility loci. We have fine-mapped 64 GWAS regions known at the conclusion of the iCOGS study using large-scale genotyping and imputation in 25 723 PrCa cases and 26 274 controls of European ancestry. We detected evidence for multiple independent signals at 16 regions, 12 of which contained additional newly identified significant associations. A single signal comprising a spectrum of correlated variation was observed at 39 regions; 35 of which are now described by a novel more significantly associated lead SNP, while the originally reported variant remained as the lead SNP only in 4 regions. We also confirmed two association signals in Europeans that had been previously reported only in East-Asian GWAS. Based on statistical evidence and linkage disequilibrium (LD) structure, we have curated and narrowed down the list of the most likely candidate causal variants for each region. Functional annotation using data from ENCODE filtered for PrCa cell lines and eQTL analysis demonstrated significant enrichment for overlap with bio-features within this set. By incorporating the novel risk variants identified here alongside the refined data for existing association signals, we estimate that these loci now explain ∼38.9% of the familial relative risk of PrCa, an 8.9% improvement over the previously reported GWAS tag SNPs. This suggests that a significant fraction of the heritability of PrCa may have been hidden during the discovery phase of GWAS, in particular due to the presence of multiple independent signals within the same regio

Evaluating children's books for whole-language learning

Whole language is a philosophy, perspective, world view, or stance; it is not a program of hierarchical components or methods. It is a grass roots movement spearheaded by teachers with empowerment of teachers and students as a central theme. Whole language is an amalgam of theories, beliefs, perspectives, and research about language, children, and learning drawn from a number of interrelated disciplines such as linguistics, psychology, philosophy, and sociology. Further, whole language is the perspective that learning occurs when information is presented as a whole rather than divided into smaller components and is thus meaningful; activities occur within a social context, and the learner is active.published or submitted for publicatio

Navigating Authoritative Discourses in a Multilingual Classroom: Conversations With Policy and Practice

Using Bakhtinian concepts of persuasive and authoritative discourse, this study reports on science and English language arts instructional practices in a multilingual, rural, fourth-grade classroom in Kenya. Situated in English as a medium of instruction (EMI) and through the use of case study, the study explores classroom discourse data to illustrate how teachers use instructional practices to reproduce, contest, or navigate prevailing institutional monolingual policies when mediating students’ access to literacy and content. By analyzing classroom discourse, the authors argue that restrictive language policies that aspire for fixity disconnect multilingual learners from their daily realities. In contrast, they call for a (re)construction of multilingual pedagogy that capitalizes on the strengths of learners, teachers, and linguistic communities by embracing students’ languages and language varieties in language learning and literacy development. In particular, implications are drawn for the use of EMI for emerging bilingual and multilingual learners. The authors identify the need to prepare teachers for a multilingual reality through legitimizing multilingual pedagogies such as translanguaging

Reading instruction and educational opportunity at the middle school level

This study used qualitative methods, as part of a 2-year collaborative university/middle school effort, to understand the instructional reading practices in effect at the seventh-grade level and to investigate whether any of the practices might be related to the differential reading performance of the school's African-American students. Few of the teachers felt comfortable teaching reading at the middle-school level. They tended to emphasize whole-class instruction, oral reading, and the coverage of required texts, practices not oriented toward helping low readers improve their reading. The low reading performance of the African-American students was affected by the school's use of homogeneous grouping, overrepresentation of African Americans in the low classes, and by the type of reading instruction offered in these classes. If middle-school students are to improve their literacy capabilities, and if past inequities are to be overturned, then middle school experts and faculty, along with literacy experts, need to work together to develop a literacy curriculum