Browsing and searching e-encyclopaedias

Educational websites and electronic encyclopaedias employ many of the same design elements, such as hyperlinks, frames and search mechanisms. This paper asks to what extent recommendations from the world of web design can be applied to e-encyclopaedias, through an evaluation of users' browsing and searching behaviour in the free, web-based versions of Encyclopaedia Britannica, the Concise Columbia Encyclopaedia and Microsoft's Encarta. It is discovered that e-encyclopaedias have a unique set of design requirements, as users' expectations are inherited from the worlds of both web and print

Excitonic Funneling in Extended Dendrimers with Non-Linear and Random Potentials

The mean first passage time (MFPT) for photoexcitations diffusion in a funneling potential of artificial tree-like light-harvesting antennae (phenylacetylene dendrimers with generation-dependent segment lengths) is computed. Effects of the non-linearity of the realistic funneling potential and slow random solvent fluctuations considerably slow down the center-bound diffusion beyond a temperature-dependent optimal size. Diffusion on a disordered Cayley tree with a linear potential is investigated analytically. At low temperatures we predict a phase in which the MFPT is dominated by a few paths.Comment: 4 pages, 4 figures, To be published in Phys. Rev. Let

High Sensitivity Mass Spectrometric Quantification of Serum Growth Hormone by Amphiphilic Peptide Conjugation

Amphiphilic peptide conjugation affords a significant increase in sensitivity with protein quantification by electrospray-ionization mass spectrometry. This has been demonstrated here for human growth hormone in serum using N-(3-iodopropyl)-N,N,N-dimethyloctylammonium iodide (IPDOA-iodide) as derivatizing reagent. The signal enhancement achieved in comparison to the method without derivatization enables extension of the applicable concentration range down to the very low concentrations as encountered with clinical glucose suppression tests for patients with acromegaly. The method has been validated using a set of serum samples spiked with known amounts of recombinant 22 kDa growth hormone in the range of 0.48 to 7.65 \mug/L. The coefficient of variation (CV) calculated, based on the deviation of results from the expected concentrations, was 3.5% and the limit of quantification (LoQ) was determined as 0.4 \mug/L. The potential of the method as a tool in clinical practice has been demonstrated with patient samples of about 1 \mug/L

Disorder and Funneling Effects on Exciton Migration in Tree-Like Dendrimers

The center-bound excitonic diffusion on dendrimers subjected to several types of non-homogeneous funneling potentials, is considered. We first study the mean-first passage time (MFPT) for diffusion in a linear potential with different types of correlated and uncorrelated random perturbations. Increasing the funneling force, there is a transition from a phase in which the MFPT grows exponentially with the number of generations $g$, to one in which it does so linearly. Overall the disorder slows down the diffusion, but the effect is much more pronounced in the exponential compared to the linear phase. When the disorder gives rise to uncorrelated random forces there is, in addition, a transition as the temperature $T$ is lowered. This is a transition from a high-$T$ regime in which all paths contribute to the MFPT to a low-$T$ regime in which only a few of them do. We further explore the funneling within a realistic non-linear potential for extended dendrimers in which the dependence of the lowest excitonic energy level on the segment length was derived using the Time-Dependent Hatree-Fock approximation. Under this potential the MFPT grows initially linearly with $g$ but crosses-over, beyond a molecular-specific and $T$-dependent optimal size, to an exponential increase. Finally we consider geometrical disorder in the form of a small concentration of long connections as in the {\it small world} model. Beyond a critical concentration of connections the MFPT decreases significantly and it changes to a power-law or to a logarithmic scaling with $g$, depending on the strength of the funneling force.Comment: 13 pages, 9 figure

A multiple imputation strategy for sequential multiple assignment randomized trials

Sequential multiple assignment randomized trials (SMARTs) are increasingly being used to inform clinical and intervention science. In a SMART, each patient is repeatedly randomized over time. Each randomization occurs at a critical decision point in the treatment course. These critical decision points often correspond to milestones in the disease process or other changes in a patient's health status. Thus, the timing and number of randomizations may vary across patients and depend on evolving patient‐specific information. This presents unique challenges when analyzing data from a SMART in the presence of missing data. This paper presents the first comprehensive discussion of missing data issues typical of SMART studies: we describe five specific challenges and propose a flexible imputation strategy to facilitate valid statistical estimation and inference using incomplete data from a SMART. To illustrate these contributions, we consider data from the Clinical Antipsychotic Trial of Intervention and Effectiveness, one of the most well‐known SMARTs to date. Copyright © 2014 John Wiley & Sons, Ltd.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/108622/1/sim6223-sup-0001-SupInfo.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/108622/2/sim6223.pd

Sexual Harassment: A Guide for Understanding and Prevention

Book review of Sexual Harassment: A Guide for Understanding and Prevention by Arjun P. Aggarwal and published by Butterworths (Toronto), 1992. (129 pp.

Skateboarding in Place: Creating and Reclaiming Namescapes Through Skatescapes

This exploration paper considers the sport/art/activity of skateboarding as it intertwines with spatial experiences, identities, and our personal and kinetic vernaculars. I try to understand what skateboarders, and Indigenous skateboarders especially, can teach us about alternative ways to understand space, place, and identity. I posit that skateboarding encourages spatial comprehension and landscape-use in particular ways, what I think of as a skatescape: a landscape as seen through skateboarders’ eyes. Through a skateboarding media and art lens, I reflect on some ways in which skateboarding influences narratives of place and belonging. I then consider these personal narratives and attempt to broaden the definition of a skatescape and in so doing speculate on how we create, share, and navigate our unique and personal spatial languages through movement and presence. Finally, I reveal that appreciating Indigenous skatescapes has illuminated a blindspot in my settler psyche: that up until recently I had not acknowledged fully that each and every spot I have ever skated was and is Indigenous land