The effects of complexity, accuracy, and fluency on communicative adequacy in oral task performance

Communicative adequacy is a key construct in second language research, as the primary goal of most language learners is to communicate successfully in real-world situations. Nevertheless, little is known about what linguistic features contribute to communicatively adequate speech. This study fills this gap by investigating the extent to which complexity, accuracy, and fluency (CAF) predict adequacy, and whether proficiency and task type moderate these relationships. In all, 20 native speakers and 80 second language users from four proficiency levels performed five tasks. Speech samples were rated for adequacy and coded for a range of CAF indices. Filled pause frequency, a feature of breakdown fluency, emerged as the strongest predictor of adequacy. Predictors with significant but smaller effects included indices of all three CAF dimensions: linguistic complexity (lexical diversity, overall syntactic complexity, syntactic complexity by subordination, and frequency of conjoined clauses), accuracy (general accuracy and accuracy of connectors), and fluency (silent pause frequency and speed fluency). For advanced speakers, incidence of false starts also emerged as predicting communicatively adequate speech. Task type did not influence the link between linguistic features and adequacy

Divergent evolution of protein conformational dynamics in dihydrofolate reductase.

Molecular evolution is driven by mutations, which may affect the fitness of an organism and are then subject to natural selection or genetic drift. Analysis of primary protein sequences and tertiary structures has yielded valuable insights into the evolution of protein function, but little is known about the evolution of functional mechanisms, protein dynamics and conformational plasticity essential for activity. We characterized the atomic-level motions across divergent members of the dihydrofolate reductase (DHFR) family. Despite structural similarity, Escherichia coli and human DHFRs use different dynamic mechanisms to perform the same function, and human DHFR cannot complement DHFR-deficient E. coli cells. Identification of the primary-sequence determinants of flexibility in DHFRs from several species allowed us to propose a likely scenario for the evolution of functionally important DHFR dynamics following a pattern of divergent evolution that is tuned by cellular environment

The effects of task type and L2 proficiency on discourse appropriacy in oral task performance

Conceived within the TBLT framework, the present study examined pedagogic tasks as vehicles for demonstrating L2 learners’ discourse appropriacy in oral production. Eighty ESL learners’ discourse appropriacy was measured using three pragmatically-oriented task types (complaint, refusal, and advice) across four different proficiency levels. The findings showed that, for all task types, as general proficiency increased, ratings of discourse appropriacy also increased. We found that there was a pronounced difference in discourse appropriacy between the intermediate and advanced proficiency levels, and that for learners at higher levels of proficiency, discourse appropriacy did not vary from task to task. In contrast, task type made a difference for less proficient learners in that the refusal task was particularly challenging compared with other tasks

Bioactivities of Traditional Medicinal Plants in Alexandria

In traditional folklore, medicinal herbs play a vital role in the prevention and treatment of microbial diseases. In the present study, the phenolic profiles of the medicinal plants Asparagus aethiopicus L., Citrullus colocynthis L., Senna alexandrina L., Kalanchoe delagoensis L., Gasteria pillansii L., Cymbopogon citratus, Brassica juncea, and Curcuma longa L. were determined by high-performance liquid chromatography with a diode-array detector method. The results revealed rich sources of important compounds such as robinin in the fruits and leaves of A. aethiopicus; caffeic acid in the tubers of A. aethiopicus and quercitrin in the leaves of G. pillansii. Further, relatively high antioxidant, antibacterial, and antifungal activities were observed in C. colocynthis fruit coat, S. alexandrina pods, and A. aethiopicus leaves, respectively. The relatively higher the bioactivities of plants extracts associated with the phenols in these plants, in particular, the more abundant the phenols. Therefore, it was concluded that the fruit coat of C. colocynthis, pods of S. alexandrina, and leaves of A. aethiopicus might be excellent sources of natural products. These plant extracts also have a wide spectrum of antimicrobial activities that could be used in the pharmaceutical industries and to control diseases

A pals-25 gain-of-function allele triggers systemic resistance against natural pathogens of C. elegans

Regulation of immunity throughout an organism is critical for host defense. Previous studies in the nematode Caenorhabditis elegans have described an “ON/OFF” immune switch comprised of the antagonistic paralogs PALS-25 and PALS-22, which regulate resistance against intestinal and epidermal pathogens. Here, we identify and characterize a PALS-25 gain-of-function mutant protein with a premature stop (Q293*), which we find is freed from physical repression by its negative regulator, the PALS-22 protein. PALS-25(Q293*) activates two related gene expression programs, the Oomycete Recognition Response (ORR) against natural pathogens of the epidermis, and the Intracellular Pathogen Response (IPR) against natural intracellular pathogens of the intestine. A subset of ORR/IPR genes is upregulated in pals-25(Q293*) mutants, and they are resistant to oomycete infection in the epidermis, and microsporidia and virus infection in the intestine, but without compromising growth. Surprisingly, we find that activation of PALS-25 seems to primarily stimulate the downstream bZIP transcription factor ZIP-1 in the epidermis, with upregulation of gene expression in both the epidermis and in the intestine. Interestingly, we find that PALS-22/25-regulated epidermal-to-intestinal signaling promotes resistance to the N. parisii intestinal pathogen, demonstrating cross-tissue protective immune induction from one epithelial tissue to another in C. elegans