Dielectrophoresis of DNA: Quantification by impedance measurements

Dielectrophoretic properties of DNA have been determined by measuring capacitance changes between planar microelectrodes. DNA sizes ranged from 100 bp to 48 kbp, DNA concentrations from below 0.1 to 70 μg∕ml. Dielectrophoretic spectra exhibited maximum response around 3 kHz and 3 MHz. The strongest response was found for very long DNA (above 10 kbp) and for short 100 bp fragments, which corresponds to the persistence length of DNA. The method allows for an uncomplicated, automatic acquisition of the dielectrophoretic properties of submicroscopical objects without the need for labeling protocols or optical accessibility.     

Environmental education in southern Africa: a case study of a secondary school in the Okavango Delta of Botswana

This study explored the extent to which teachers integrate environmental education and local environmental knowledge into the curriculum of a secondary school in the Okavango Delta of Botswana. In doing so, the study explored the potential value of place-based education in redressing concerns brought to light in postcolonial critiques of education in southern Africa. The study found that teachers sought to integrate environmental education into the curriculum through lessons that included references to local place names and local flora and fauna, lessons addressing issues related to environmental resource management in the region, and the acknowledgment and celebration of traditional lifestyle activities in the schools. The study also found that efforts to integrate environmental education into the curriculum were limited by a lack of educational resources needed to support these endeavors as well as a lack of adequate teacher training promoting this educational goal. The results also illustrate the potential value of place-based education in redressing the legacy of southern Africa’s colonial past in schools in Botswana and southern Africa.     

The Framing Discussion: Connecting Student Experience with Mathematical Knowledge

This article introduces the framing discussion, an informal discussion of a mathematical problem that takes place at the beginning of a lesson or unit. The purpose of the framing discussion is to assess student knowledge, motivate student interest, and to serve as a basis for guiding students to more formal mathematical knowledge. The article discusses the design criteria and the discourse moves necessary to execute an effective framing discussion.     

Infant and maternal sensitivity to interpersonal timing

A perturbation paradigm was employed to assess 3- and 6-month-old infants' and their mothers' sensitivity to a 3-s temporal delay implemented in an ongoing televised interaction. At both ages, the temporal delay affected infant but not maternal behavior and only when implementing the temporal delay in maternal (Experiment 1, N=64) but not infant (Experiment 2, N=60) behavior. In addition, the experimental manipulation influenced promptness of maternal smiling responses reliably more than promptness of infant smiling responses. The findings suggest that the timing of maternal behavior plays an important role in infants' perception of maternal responsiveness, whereas mothers seem to monitor general aspects of infant behavior such as overall level of engagement.     

Evaluating multimodal relevance feedback techniques for medical image retrieval

Medical image retrieval can assist physicians in finding information supporting their diagnosis and fulfilling information needs. Systems that allow searching for medical images need to provide tools for quick and easy navigation and query refinement as the time available for information search is often short. Relevance feedback is a powerful tool in information retrieval. This study evaluates relevance feedback techniques with regard to the content they use. A novel relevance feedback technique that uses both text and visual information of the results is proposed. The two information modalities from the image examples are fused either at the feature level using the Rocchio algorithm or at the query list fusion step using a common late fusion rule. Results using the ImageCLEF 2012 benchmark database for medical image retrieval show the potential of relevance feedback techniques in medical image retrieval. The mean average precision (mAP) is used as the evaluation metric and the proposed method outperforms commonly-used methods. The baseline without feedback reached 16 % whereas the relevance feedback with 20 images reached up to 26.35 % with three steps and when using 100 images up to 34.87 % in four steps. Most improvements occur in the first two steps of relevance feedback and then results start to become relatively flat. This might also be due to only using positive feedback as negative feeback often also improves results after more steps. The effect of relevance feedback in automatically spelling corrected and translated queries is investigated as well. Results without mistakes were better than spell-corrected results but the spelling correction more than double results over non-corrected retrieval. Multimodal relevance feedback has shown to be able to help visual medical information retrieval. Next steps include integrating semantics into relevance feedback techniques to benefit from the structured knowledge of ontologies and experimenting on the fusion of text and visual information.     

Teachers’ perceptions of their most significant change: source,impact, and process

The purpose of the study was to examine the differences among significant changes in the practice of individual teachers. Seventeen US teachers were interviewed about the most successful change in their teaching career. The differences in teacher change were based primarily on the source and impact of the change. The sources of change were divided into two categories: other-initiated or self-initiated. The level of impact was determined in three ways: by whether teachers described a new practice, a new direction, or a change in their beliefs. By organizing according to both the source and impact of the change, four types of change were identified: Response to School Initiatives, Professional Development Initiatives, Student-Centered Changes, and Self-Designed Changes. Self-Designed changes were further distinguished based on the time required for the change process. Implications for developing new strategies to foster teacher development are discussed.     

Renal lactate elimination is maintained during moderate exercise in humans

Reduced hepatic lactate elimination initiates blood lactate accumulation during incremental exercise. In this study, we wished to determine whether renal lactate elimination contributes to the initiation of blood lactate accumulation. The renal arterial-to-venous (a-v) lactate difference was determined in nine men during sodium lactate infusion to enhance the evaluation (0.5 mol x L(-1) at 16 ± 1 mL x min(-1); mean ± s) both at rest and during cycling exercise (heart rate 139 ± 5 beats x min(-1)). The renal release of erythropoietin was used to detect kidney tissue ischaemia. At rest, the a-v O(2) (CaO(2)-CvO(2)) and lactate concentration differences were 0.8 ± 0.2 and 0.02 ± 0.02 mmol x L(-1), respectively. During exercise, arterial lactate and CaO(2)-CvO(2) increased to 7.1 ± 1.1 and 2.6 ± 0.8 mmol x L(-1), respectively (P < 0.05), indicating a -70% reduction of renal blood flow with no significant change in the renal venous erythropoietin concentration (0.8 ± 1.4 U x L(-1)). The a-v lactate concentration difference increased to 0.5 ± 0.8 mmol x L(-1), indicating similar lactate elimination as at rest. In conclusion, a -70% reduction in renal blood flow does not provoke critical renal ischaemia, and renal lactate elimination is maintained. Thus, kidney lactate elimination is unlikely to contribute to the initial blood lactate accumulation during progressive exercise.     

Leveraging student engagement for student and institutional success

We all know the importance of student engagement to student learning. Gavin W. Henning argues that the upside doesn't end there … the institution as a whole also benefits.