Size-dependent trajectories of DNA macromolecules due to insulative dielectrophoresis in submicrometer-deep fluidic channels

In this paper, we demonstrate for the first time that insulative dielectrophoresis can induce size-dependent trajectories of DNA macromolecules. We experimentally use λ (48.5 kbp) and T4GT7 (165.6 kbp) DNA molecules flowing continuously around a sharp corner inside fluidic channels with a depth of 0.4 μm. Numerical simulation of the electrokinetic force distribution inside the channels is in qualitative agreement with our experimentally observed trajectories. We discuss a possible physical mechanism for the DNA polarization and dielectrophoresis inside confining channels, based on the observed dielectrophoresis responses due to different DNA sizes and various electric fields applied between the inlet and the outlet. The proposed physical mechanism indicates that further extensive investigations, both theoretically and experimentally, would be very useful to better elucidate the forces involved at DNA dielectrophoresis. When applied for size-based sorting of DNA molecules, our sorting method offers two major advantages compared to earlier attempts with insulative dielectrophoresis: Its continuous operation allows for high-throughput analysis, and it only requires electric field strengths as low as ∼10 V∕cm.     

Supervision and evaluation: The Wyoming perspective

The intent of this study was to assess the perceptions and actions of Wyoming principals concerning their role in supervising and evaluating teachers. A survey was sent to all 286 principals in the state of Wyoming, of which, 143 returned surveys, a response rate of 50%. Findings suggested that principals utilized supervisory behaviors more often than evaluative behaviors. Elementary principals perceived their evaluative practices as significantly more prevalent than secondary principals. Furthermore, principals indicated that their greatest frustrations in supervising teachers were time, the evaluation instrument, and teachers’ unwillingness to change. Additionally, findings suggested that Wyoming principals utilized classroom walkthroughs because they provided a snapshot of teaching and provided a medium for providing feedback. In regards to developmental supervision, principals indicated that novice teachers received much more supervision than veteran teachers. However, their reported use of differentiated supervision only applied to teacher autonomy concerning professional development goals. Principals reported that teachers had little input concerning the methods by which they were supervised. Finally, a majority of the Wyoming principals felt that improvement plans were effective at changing mediocre teaching behaviors, but 40% were speculative that such plans truly remediated poor teachers.     

Multi‐sensory storytelling as an aid to assisting people with profound intellectual disabilities to cope with sensitive issues: a multiple research methods analysis of engagement and outcomes

The importance of storytelling in social, cultural and educational contexts is well established and documented. The extension of storytelling to people with profound intellectual and multiple disabilities (PIMD) has in recent years been undertaken with an emphasis on the value of sensory experience and the context storytelling provides for social interaction. The present study builds on earlier curriculum orientated research with a view to describe patterns of social and story‐oriented interaction during storytelling. The stories dealt with sensitive topics raised by family carers who wished the young person with PIMD to understand. Behavioural observation during storytelling sessions explored changes in engagement while semi‐structured interviews with parents and professionals explored the extent to which the experience had benefitted the young person with respect to the sensitive topic. Positive changes in engagement with the story were shown for seven of the eight participants. For six of the seven, a parent and a professional agreed that the outcome of the experience positively enabled the participant to cope better with the sensitive topic. The specific multi‐sensory storytelling factors leading to these outcomes are discussed, as is the issue of proxy reporting and determining the nature of understanding in people with PIMD.     

Cumulative childhood trauma and psychological maladjustment of sexually abused children in Korea: Mediating effects of emotion regulation

The purpose of the present study was to identify the mediating effects of emotion regulation on the association between cumulative childhood trauma and behavior problems in sexually abused children in Korea, using structural equation modeling (SEM). Data were collected on 171 children (ages 6–13 years) referred to a public counseling center for sexual abuse in Seoul, Korea. Cumulative childhood traumas were defined on the basis of number of traumas (physical abuse, witnessing domestic violence, neglect, traumatic separation from parent, and sexual abuse) and the severity and duration of traumas. Children were evaluated by their parents on emotion regulation using the Emotion Regulation Checklist and internalizing and externalizing behavior problems using the Korean-Child Behavior Checklist. SEM analyses confirmed the complete mediation model, in which emotion dysregulation fully mediates the relationship between cumulative childhood traumas and internalizing/externalizing behavior problems. These findings indicate that emotion regulation is an important mechanism that can explain the negative effects of cumulative childhood traumas and that there is a need to focus on emotion regulation in sexually abused children exposed to cumulative trauma.     

Teaching Lean Six Sigma within A Supply Chain Context: The Airplane Supply Chain Simulation

Lean six sigma is a management methodology that firms can employ to achieve substantial improvement in supply chain performance. However, few pedagogical exercises facilitate students’ use of a comprehensive set of lean six sigma principles within a supply chain context. We describe the Airplane Supply Chain Simulation that helps students understand how lean six sigma concepts may be leveraged to improve supply chain performance. The basis of this simulation is a four‐tier supply chain, consisting of suppliers (two tiers), a manufacturer, and a customer, that produces three models of paper airplanes to meet randomly distributed customer demand. In the first of three successive runs, a highly structured simulation is executed in which supply chain roles are well defined, material flows are convoluted, and a “push” production strategy is followed. The first simulation as the “current state” and, for the second and third simulation runs, challenge competing student teams to leverage lean six sigma concepts to develop a “future state” that enables the fulfillment of all customer orders at the lowest cost. Results based on statistical analyses of survey response data from 194 MBA students show that the Airplane Supply Chain Simulation is an effective participative, team‐based learning tool.     

Poly(vinyl alcohol)-heparin biosynthetic microspheres produced by microfluidics and ultraviolet photopolymerisation

Biosynthetic microspheres have the potential to address some of the limitations in cell microencapsulation; however, the generation of biosynthetic hydrogel microspheres has not been investigated or applied to cell encapsulation. Droplet microfluidics has the potential to produce more uniform microspheres under conditions compatible with cell encapsulation. Therefore, the aim of this study was to understand the effect of process parameters on biosynthetic microsphere formation, size, and morphology with a co-flow microfluidic method. Poly(vinyl alcohol) (PVA), a synthetic hydrogel and heparin, a glycosaminoglycan were chosen as the hydrogels for this study. A capillary-based microfluidic droplet generation device was used, and by varying the flow rates of both the polymer and oil phases, the viscosity of the continuous oil phase, and the interfacial surface tension, monodisperse spheres were produced from ∼200 to 800 μm. The size and morphology were unaffected by the addition of heparin. The modulus of spheres was 397 and 335 kPa for PVA and PVA/heparin, respectively, and this was not different from the bulk gel modulus (312 and 365 for PVA and PVA/heparin, respectively). Mammalian cells encapsulated in the spheres had over 90% viability after 24 h in both PVA and PVA/heparin microspheres. After 28 days, viability was still over 90% for PVA-heparin spheres and was significantly higher than in PVA only spheres. The use of biosynthetic hydrogels with microfluidic and UV polymerisation methods offers an improved approach to long-term cell encapsulation.     

亲爱的父亲们,节日快乐!

Hi Brad, The Father's Day is coming.I am always too shy to express my feeling to my father as he,in my eyes,is so serious.Maybe his action has said all for him,and there's so little left to the words.Brad,do you also prefer to have actions instead of words to say everything for you? Please tell me more about your story of being a father.