Holomorph of generalized Bol loops II

The notion of the holomorph of a generalized Bol loop (GBL) is characterized afresh. The holomorph of a right inverse property loop (RIPL) is shown to be a GBL if and only if the loop is a GBL and some bijections of the loop are right (middle) regular. The holomorph of a RIPL is shown to be a GBL if and only if the loop is a GBL and some elements of the loop are right (middle) nuclear. Necessary and sufficient condition for the holomorph of a RIPL to be a Bol loop are deduced. Some algebraic properties and commutative diagrams are established for a RIPL whose holomorph is a GBL.Comment: 18 pages, 5 figures. arXiv admin note: substantial text overlap with arXiv:1501.0462

Designing for interaction

At present, the design of computer-supported group-based learning (CS)GBL) is often based on subjective decisions regarding tasks, pedagogy and technology, or concepts such as ‘cooperative learning’ and ‘collaborative learning’. Critical review reveals these concepts as insufficiently substantial to serve as a basis for (CS)GBL design. Furthermore, the relationship between outcome and group interaction is rarely specified a priori. Thus, there is a need for a more systematic approach to designing (CS)GBL that focuses on the elicitation of expected interaction processes. A framework for such a process-oriented methodology is proposed. Critical elements that affect interaction are identified: learning objectives, task-type, level of pre-structuring, group size and computer support. The proposed process-oriented method aims to stimulate designers to adopt a more systematic approach to (CS)GBL design according to the interaction expected, while paying attention to critical elements that affect interaction. This approach may bridge the gap between observed quality of interaction and learning outcomes and foster (CS)GBL design that focuses on the heart of the matter: interaction

Analytical device model for graphene bilayer field-effect transistors using weak nonlocality approximation

We develop an analytical device model for graphene bilayer field-effect transistors (GBL-FETs) with the back and top gates. The model is based on the Boltzmann equation for the electron transport and the Poisson equation in the weak nonlocality approximation for the potential in the GBL-FET channel. The potential distributions in the GBL-FET channel are found analytically. The source-drain current in GBL-FETs and their transconductance are expressed in terms of the geometrical parameters and applied voltages by analytical formulas in the most important limiting cases. These formulas explicitly account for the short-gate effect and the effect of drain-induced barrier lowering. The parameters characterizing the strength of these effects are derived. It is shown that the GBL-FET transconductance exhibits a pronounced maximum as a function of the top-gate voltage swing. The interplay of the short-gate effect and the electron collisions results in a nonmonotonic dependence of the transconductance on the top-gate length.Comment: 12 pages, 7 figure

Financing smallholder agriculture: an experiment with agent-intermediated microloans in India

We explore the hypothesis that traditional joint-liability microfinance programs fail to increase borrower incomes in part because they cannot screen out unproductive borrowers. In randomly selected villages in West Bengal, India, we implemented trader-agent-intermediated lending (TRAIL), in which local trader-lender agents were incentivized through repayment-based commissions to select borrowers for individual liability loans. In other randomly selected villages, we organized a group-based lending (GBL) program in which individuals formed 5-member groups and received joint liability loans. TRAIL loans increased the production of the leading cash crop by 27% and farm incomes by 22%. GBL loans had insignificant effects. We develop and test a theoretical model of borrower selection and incentives. Farmers selected by the TRAIL agents were more able than those who self-selected into the GBL scheme; this pattern of selection explains at least 30–40% of the observed difference in income impacts.Accepted manuscrip

The Gamma-Butyrolactone Model of Absence Epilepsy: Acute and Chronic Effects in Wistar Rats

Objectives: We studied the electroencephalographic (EEG) and behavioral changes of the chemical model of generalized absence epilepsy induced by acute and chronic administration of gamma-butrolactone (GBL), a prodrug of gamma-hydroxybutyric acid.Methods: Adult male Wistar rats under anesthesia were implanted with bilateral cortical recording electrodes. The rats were administered 30 intraperitoneal injections of GBL twice daily from Monday to Friday and EEG was recorded 20 min before and 40 min after GBL injections. In order to monitor spontaneous spike-and-wave discharges (SWDs), the baseline EEGs on the subsequent Monday mornings after the first, second and third weekends were recorded for 90 min.Results: The intraperitoneal administration of GBL caused a rapid onset of bilaterally synchronous SWDs in the cortical EEG accompanied by behavioral immobility, vacant-staring and vibrissal twitching. By repeated GBL injections, animals displayed spontaneous bilateral synchronous SWDs in the baseline EEG on the Monday morning session after the GBL-free weekend period (60 h after the Friday afternoon injection).Conclusion: The present study reports the acute and chronic effects of the systemic administration of GBL. The chronic systemic application of GBL may represent a model of epileptogenesis for absence epilepsy

SELEX-Based Identification of Synthetic Binding Sites for Streptomyces acidiscabies 84.104 γ-Butyrolactone Receptors: SabS and SabR.

Bacteria belonging to the Gram positive genus Streptomyces produce many secondary metabolite natural products of pharmaceutical importance and undergo a complex program of morphological differentiation. The expression of genes involved in these processes is often regulated by γ-butyrolactone (GBL) interactions with cognate GBL receptors. GBL receptors regulate gene expression by binding specific AT-rich DNA sequences known as autoregulatory elements (ARE) in response to available intracellular GBL pools. We previously identified two S. acidiscabies GBL receptor genes, sabR and sabS, flanking a gene encoding a GBL synthase homolog sabA. Genetic and biochemical studies revealed that sabR negatively regulates sabS expression by binding an ARE located in the 5’ region of sabS, while sabS mutants overproduce the type II aromatic polyketide WS5995B and exhibit a conditional impairment in morphological differentiation. In order to further understand the role of GBL receptors in regulating cellular behavior, we have applied synthetic and genomic SELEX (Systematic Evolution of Ligands by Exponential Enrichment) methods to identify AREs for recombinant SabR and SabS. Following variable rounds of iterative SELEX, DNA substrates bound to the proteins were cloned and sequenced. Sequence analysis of cloned products revealed DNA sequences that resemble AT-rich ARE sequences. This method can now be used to identify target genes regulated by these GBL receptors and compare the properties of binding interactions of GBL receptors with physiological and synthetic DNA substrates

Effect of dietary Ginkgo biloba leaf on the growth performance and nonspecific immunity of red swamp crayfish Procambarus clarkii

This trial investigated the effect of dietary Ginkgo biloba leaf (GBL) on the growth performance and nonspecific immunity of red swamp crayfish Procambarus clarkii. 180 Crayfishes were randomly divided into three groups. One group was fed with basic diet, whereas the other two groups were fed with diets containing 1% and 3% GBL. After 32 days of feeding, GBL addition tended to increase the body weight gain rate compared with control. In 3% GBL group, the bodyweight gain rate of male crayfish was higher than that of female crayfish. While female crayfish were advantageous in terms of meat yield. Liver-related indexes were influenced by GBL addition and 3% GBL could reduce glutamic pyruvic transaminase and glutamic oxaloacetic transaminase as well as total cholesterol in male crayfish, showing its function in liver protection. Moreover, GBL addition effects on liver protection was better in male crayfish than female crayfish

Graphene Bilayer Field-Effect Phototransistor for Terahertz and Infrared Detection

A graphene bilayer phototransistor (GBL-PT) is proposed and analyzed. The GBL-PT under consideration has the structure of a field-effect transistor with a GBL as the channel and the back and top gates. The positive bias of the back gate results in the formation of conducting source and drain sections in the channel, while the negatively biased top gate provides the potential barrier which is controlled by the charge of the photogenerated holes. The features of the GBL-PT operation are associated with the variations of both the potential distribution and the energy gap in different sections of the channel when the gate voltages and the charge in the barrier section change. Using the developed GBL-PT device model, the spectral characteristics, dark current, responsivity and detectivity are calculated as functions of the applied voltages, energy of incident photons, intensity of electron and hole scattering, and geometrical parameters. It is shown that the GBL-PT spectral characteristics are voltage tuned. The GBL-PT performance as photodetector in the terahertz and infrared photodetectors can markedly exceed the performance of other photodetectors.Comment: 7 Pages, 7 figure

Teachers as designers of GBL scenarios: Fostering creativity in the educational settings

This paper presents a research started in 2010 with the aim of fostering the creativity of teachers through the design of Game-Based Learning scenarios. The research has been carried out involving teachers and trainers in the co-design and implementation of digital games as educational resources. Based on the results grained from the research, this paper highlights successful factors of GBL, as well as constraints and boundaries that the introduction of innovative teaching and learning practices faces within educational settings