Maximal Height Scaling of Kinetically Growing Surfaces

The scaling properties of the maximal height of a growing self-affine surface with a lateral extent $L$ are considered. In the late-time regime its value measured relative to the evolving average height scales like the roughness: $h^{*}_{L} \sim L^{\alpha}$. For large values its distribution obeys $\log{P(h^{*}_{L})} \sim -A({h^{*}_{L}}/L^{\alpha})^{a}$, charaterized by the exponential-tail exponent $a$. In the early-time regime where the roughness grows as $t^{\beta}$, we find $h^{*}_{L} \sim t^{\beta}[\ln{L}-({\beta\over \alpha})\ln{t} + C]^{1/b}$ where either $b=a$ or $b$ is the corresponding exponent of the velocity distribution. These properties are derived from scaling and extreme-values arguments. They are corroborated by numerical simulations and supported by exact results for surfaces in 1D with the asymptotic behavior of a Brownian path.Comment: One reference added. Minor stylistic changes in the abstarct and the paper. 4 pages, 3 figure

Teaching Writing in Online Distance Education: Supporting Student Success

An intervention is a counseling action an instructor may use to support a student who struggles to work productively in an online writing instruction (OWI) course. Interventions may increase retention and graduation rates at institutions as well as increase student and teacher satisfaction (Allen, Bourhis, Burrell, and Mabry, 2002; Archambault and Crippen, 2009; McCombs, Ufnar, and Shepherd, 2007; O'Dwyer, Carey, and Kleiman, 2007; Stein, Wanstreet, Calvin, Overtoom, and Wheaton, 2005; Sun, Tsai, Finger, Chen, and Yeh, 2008). In Moore's (1993) Theory of Transaction Distance, interventions are called "advice and counsel," and they are a crucial component of the program structure element in the theory. Many researchers recommend early identification and intervention for struggling students (Archambault et al., 2010; Simpson, 2004). For example, Simpson (2004) found that early interventions following Keller's (1987) ARCS model (Attention, Relevance, Confidence and Satisfaction) were effective in helping students complete a course. In addition, Simpson found that such interventions could be cost effective; however, there are many open variables when calculating cost. As researchers and online instructors, the authors recommend early intervention activities performed by email and text messaging at many opportunistic intervention points during the course of the instruction. As well, developing an intervention strategy prior to course beginning to assist in planning and preparation is advocated and recommended

Intervention in Online Writing Instruction: An Action-theoretical Perspective

This analysis argues for an interwoven perspective of motivation, engagement, agency, and action in Online Writing Instruction (OWI) compiled from shared elements of empirical research in online education, writing instruction, and especially student academic engagement in traditional classrooms, where the research domain is comparatively mature. Engagement is the common element shared by these domains. In online education research, engagement is sometimes understood through intentional student actions. In writing instruction, engagement is commonly understood through human agency. In academic settings, engagement can be seen as a foundational part of Self-Determination Theory, which is comprised of cognitive, behavioral, and emotional engagement (Deci and Ryan, 1985). Educators often find measures of engagement valuable because they are reliable predictors of student outcomes, and they suggest a reasonable point of intervention for struggling students. A measure of agentic engagement, which describes the extent to which a student exerts agency to personalize a learning experience, could add value to measures of engagement, especially in OWI where actions and agency are integral to student success. In addition, a focus on engagement and intervention/remediation may offer an opportunity for students to succeed in learning online, not just in OWI, which is a valued skill in the workplace

A capability approach for online primary and secondary students with disabilities

A capability approach was used to identify and synthesise research studies about online students with disabilities in primary and secondary school (aged five to 18 years) in an attempt to describe the experience from an empirical perspective. A capability approach is intended to maximise agency and can be used to describe the extent to which individuals are able to use limited resources to build a satisfying and enjoyable life. In this analysis, a derived capability set was used to narrow the larger body of research about primary and secondary students in online education in order to consider only studies that described ways in which students successfully used online education to maximise agency. The derived capability set was: autonomy, judgement, practical reason, affiliation, high school graduation and a desire to help others. A method for deriving the capability set and ways in which a capability approach fails to describe this experience are discussed

An Entropic Mechanism of Generating Selective Ion Binding in Macromolecules

Several mechanisms have been proposed to explain how ion channels and transporters distinguish between similar ions, a process crucial for maintaining proper cell function. Of these, three can be broadly classed as mechanisms involving specific positional constraints on the ion coordinating ligands which arise through: a "rigid cavity", a 'strained cavity' and 'reduced ligand fluctuations'. Each operates in subtly different ways yet can produce markedly different influences on ion selectivity. Here we expand upon preliminary investigations into the reduced ligand fluctuation mechanism of ion selectivity by simulating how a series of model systems respond to a decrease in ligand thermal fluctuations while simultaneously maintaining optimal ion-ligand binding distances. Simple abstract-ligand models, as well as simple models based upon the ion binding sites in two amino acid transporters, show that limiting ligand fluctuations can create ion selectivity between Li(+), Na(+) and K(+) even when there is no strain associated with the molecular framework accommodating the different ions. Reducing the fluctuations in the position of the coordinating ligands contributes to selectivity toward the smaller of two ions as a consequence of entropic differences.This work was funded by an Australian Postgraduate Award from the Australian Government. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript

Understanding Online Teacher Best Practices: A Thematic Analysis to Improve Learning

The purpose of this study was to examine brick-and-mortar and online teacher best practice themes using thematic analysis and a newly developed theory-based analytic process entitled Synthesized Thematic Analysis Criteria (STAC). The STAC was developed to facilitate the meaningful thematic analysis of research based best practices of K-12 education delivery options. In the study, data for the thematic analysis consisted of published research about best practices in both brick-and-mortar and online education. The use of both brick-and-mortar as well as online teacher best practices provided an opportunity to identify commonalities among these modes of delivery. Based on these commonalities, the thematic analysis detected emergent themes, which could be used as a foundation upon which online teachers might build specialized practice. As well, research-validated teacher best practice themes generated from this study may be considered a starting point for defining teacher best practices in online education and for their development. Emergent themes were discussed in the context of the data and the environment of online education. The STAC analytic process provides a foundation for analysis and may be used by researchers for other thematic analyses in the future

Understanding online K-12 students through a demographic study

Online K-12 learning opportunities have proliferated, but much remains to be understood about the characteristics of participating students. This study presents a demographic profile of fulltime, K-12 online learners today and compares them with public school students nationwide in the United States. The data was collected from a parent survey that produced 119,155 valid responses/records for students enrolled full-time in online K-12 public schools in 43 states. The study shows that the online student population includes somewhat more females than males, and more middle school than elementary or high school students. White students are overrepresented among full-time online learners compared with their share of the nationwide student population, while Hispanic/Latino and Asian/Pacific Islander students are underrepresented. Gifted and talented students and English language learners (ELLs) are also underrepresented. These data provide a baseline for more detailed explorations and can assist practitioners, policy makers, and researchers in making important decisions about online education that have implications for all students

Prosthesis Prescription Protocol of the Arm (PPP-Arm):The implementation of a national prosthesis prescription protocol

Background and aim: In order to create more uniformity in the prescription of upper limb prostheses by Dutch rehabilitation teams, the development and implementation of a Prosthesis Prescription Protocol of the upper limb (PPP-Arm) was initiated. The aim was to create a national digital protocol to structure, underpin, and evaluate the prescription of upper limb prostheses for clients with acquired or congenital arm defects. Technique: Prosthesis Prescription Protocol of the Arm (PPP-Arm) was developed on the basis of the International Classification of Functioning and consisted of several layers. All stakeholders (rehabilitation teams, orthopedic workshops, patients, and insurance companies) were involved in development and implementation. A national project coordinator and knowledge brokers in each team were essential for the project. Discussion: PPP-Arm was successfully developed and implemented in nine Dutch rehabilitation teams. The protocol improved team collaboration, structure, and completeness of prosthesis prescriptions and treatment uniformity and might be interesting for other countries as well

A kinetic study of cation transport in erythrocytes from uremic patients

A kinetic study of cation transport from uremic patients. We previously described in red blood cells (RBCs) from uremic patients on dialysis a reduction in sodium (Na) efflux through the Na, potassium (K) cotransport system (Na,K CoT) while Na efflux through the Na,K pump was normal. We then examined Na efflux in fresh cells and in cells loaded to obtain one level of intracellular sodium (Nai) concentration at about 25 mmol/liter cell. In the present study we used similar cation flux methodology to examine the kinetics of cation efflux through the Na,K pump and Na,K CoT in uremic patients on dialysis. RBCs were Na-loaded to attain five different levels of Nat concentration over a range of 5 to 50 mmol/liter cells using the ionophore nystatin. At each level of Na-loading, the Nai achieved was similar in RBCs from controls and patients. Ouabain–sensitive Na efflux through the Na,K pump showed no difference in rate between normals and dialysis patients. When the kinetic parameters of this transport pathway were considered, the apparent affinity (K0.5) for sodium was not significantly different between controls and patients (18.4 ± 2.3 vs. 20.0 ± 2.6 mmol/liter cell) and the maximal velocity of efflux (Vmax) was also not different between controls and patients (9.6 ± 0.7 vs. 8.5 ± 1.2 mmol/liter cell/hr). Comparison of Nai-activated Na versus K efflux rates through the Na,K CoT in normal subjects demonstrated similar saturation kinetics, (K0.5 15.8 ± 3.3 vs. 12.2 ± 2.8 mmol/liter cell, Vmax0.81 ± 0.1 vs. 0.78 ± 0.1 mmol/liter cell/hr) consistent with the known stoichiometric ratio of 1 Na:l K:2 C1 described for this mechanism. In dialysis patients Nai-activated, Na,K CoT-mediated Na efflux was markedly reduced. Analysis of the kinetic parameters of Na1-activated Na efflux showed that the reduced RBC Na,K CoT is due to reduction in Vmax and not to a change in K0.5 Maximum furosemide–sensitive K efflux rate was also reduced in dialysis patients. However, instead of exhibiting the anticipated saturation kinetics observed for Na, the K efflux rates were high at low levels of Nai and remained unchanged with increasing Nai concentrations. Ouabain- and furosemide-resistant Na and K effluxes were not significantly different between normals and dialysis patients. We conclude that Na efflux through RBC Na,K pump is intact over a wide range of Nai concentrations in dialysis patients. On the other hand, the furosemide–sensitive co-efflux of Na and K, which in normal RBCs displayed a typical 1 Na to 1 K transport characteristic, was quantitatively and qualitatively altered in dialysis patients. The maximum efflux rate of both Na and K was reduced and in addition, the usual stoichiometric ratio for Na and K exit through this furosemide–sensitive pathway was no longer observed

Teacher self-efficacy in online education: a review of the literature

Although empirical validation of teacher self-efficacy in face-to-face environments continues, it remains a relatively new construct in online education. This literature review, which was conducted over academic databases and which examined work published in the past 15 years, explores three areas of research about teacher self-efficacy in online education: (1) ease of adopting online teaching, (2) online teaching self-efficacy in comparison to demographic and experience variables and (3) changes in teacher self-efficacy in professional development scenarios where self-efficacy was measured before and after treatment. Research studies demonstrate agreement (or no discernible disagreement) in the importance of system/curriculum quality in the implementation of online learning and the recognition that a measure of self-efficacy in online pedagogy has not yet been empirically derived. Researchers continue to examine the balance of technological and pedagogical knowledge that supports the development of teacher self-efficacy, the role of learner self-efficacy in teacher self-efficacy and whether teacher self-efficacy differs fundamentally in online education. In addition, it seems clear that empirical validation of the association of teacher self-efficacy and student success has yet to occur in online education with the rigour seen in face-to-face modes of delivery