Spatial competition and regulatory change in the grain handling and transportation system in western Canada

The grain handling and transportation system (GHTS) has been a defining component of the western Canadian economy since the early part of the last century. Only two major railways serve the grain handling industry, so the potential for the exercise of market power in transportation appears to be significant. In fact, spatially oriented regulations applicable to railways exist in Canada to mitigate this, but to date they have not often been used by shippers. While the reasons for this are not completely clear, we suggest that the regulations are now inadequate for the current state of the GHTS. Using a unique data set from the year 2000, we assess the effect on the grain handling industry of modifications to these regulations, and find that significant gains for shippers from these modifications are possible. These gains are computed to be on the order of C$10–15 million per year for grain shippers alone. We would like to thank conference and presentation participants (Transportation Research Board, Canadian Agricultural Economics Society, University of British Columbia, University of Leeds and California State University, Long Beach) as well as the anonymous reviewers who commented on the earlier versions of this paper. We would also like to acknowledge support from the Saskatchewan Department of Highways.     

Charge collection and pore filling in solid-state dye-sensitized solar cells

The solar to electrical power conversion efficiency for dye-sensitized solar cells (DSCs) incorporating a solid-state organic hole-transporter can be over 5%. However, this is for devices significantly thinner than the optical depth of the active composites and by comparison to the liquid electrolyte based DSCs, which exhibit efficiencies in excess of 10%, more than doubling of this efficiency is clearly attainable if all the steps in the photovoltaic process can be optimized. Two issues are currently being addressed by the field. The first aims at enhancing the electron diffusion length by either reducing the charge recombination or enhancing the charge transport rates. This should enable a larger fraction of photogenerated charges to be collected. The second, though less actively investigated, aims to improve the physical composite formation, which in this instance is the infiltration of mesoporous TiO(2) with the organic hole-transporter 2,2',7,7'-tetrakis(N,N-di-p-methoxypheny-amine)-9,9'-spirobifluorene (spiro-MeOTAD). Here, we perform a broad experimental study to elucidate the limiting factors to the solar cell performance. We first investigate the charge transport and recombination in the solid-state dye-sensitized solar cell under realistic working conditions via small perturbation photovoltage and photocurrent decay measurements. From these measurements we deduce that the electron diffusion length near short-circuit is as long as 20?μm. However, at applied biases approaching open-circuit potential under realistic solar conditions, the diffusion length becomes comparable with the film thickness, ～2?μm, illustrating that real losses to open-circuit voltage, fill factor and hence efficiency are occurring due to ineffective charge collection. The long diffusion length near short-circuit, on the other hand, illustrates that another process, separate from ineffective charge collection, is rendering the solar cell less than ideal. We investigate the process of TiO(2) mesopore infiltration with spiro-MeOTAD by examining the cross-sectional images of and performing photo-induced absorption spectroscopy on devices with a range of thickness, infiltrated with spiro-MeOTAD with a range of concentrations. We present our interpretation of the mechanism for material infiltration, and by improving the casting conditions demonstrate efficient charge collection through devices of over 7?μm in thickness. This investigation represents an improvement in our understanding of the limiting factors to the dye-sensitized solar cell. However, much work, focused on composite formation and improved kinetic competition, is required to realize the true potential of this concept.     

Herding nanotransporters: localized activation via release and sequestration of control molecules

A challenge for nanotechnology is the dynamic and specific control of nanomachines by the user. Molecular shuttles, consisting of cargo-binding microtubules propelled by surface-immobilized kinesin motor proteins, are an example of a nanoscale system that ideally can be selectively activated at programmable locations and times. Here we discuss a biomimetic solution where activating molecules are delivered locally via photolysis of a caged compound and subsequently sequestered in an enzymatic network. The controlled sequestration of the activator not only creates a rapid deactivation when the stimulus is removed but also sharpens the concentration profile of the rapidly diffusing activator. This improvement comes at the expense of a reduced efficiency in the utilization of the activator molecules, suggesting that these nanosystems are most efficiently addressed as a swarm rather than as individuals. Our work represents a step toward transferring the cellular control strategies of molecular activation to bionanotechnology.     

Label-free protein recognition two-dimensional array using nanomechanical sensors

We demonstrate two-dimensional multiplexed real-time, label-free antibody-antigen binding assays by optically detecting nanoscale motions of two-dimensional arrays of microcantilever beams. Prostate specific antigen (PSA) was assayed using antibodies covalently bound to one surface of the cantilevers by two different surface chemistries, while the nonreaction surfaces were passivated by poly(ethylene glycol)-silane. PSA as low as 1 ng/mL was detected while 2 mg/microl of bovine serum albumin induced only negligible deflection on the cantilevers.     

The Advantages of Partitioning Multicast Transmissions in a Single-Hop Optical WDM Network*

In a single-hop WDM optical network, a straightforward approach to implementing multicasting is to schedule a single transmission to multiple destinations so that all of the destinations may receive the same transmission by tuning their receivers to the same channel at the same time. Although scheduling a single transmission in this manner reduces the amount of transmitter and channel resources being used, it may also place a burden on the receivers in the network. If all receivers do not become available at the same time, then some receivers may have to wait (and be idle) for significantly long periods of time before receiving the message. In this paper, we investigate methods for partitioning a multicast group into a number of smaller subgroups and for scheduling a separate transmission for each of these subgroups. We show that this approach more effectively conserves and balances the usage of transmitter and receiver resources in the network and may lead to significantly improved system performance over the conventional single-transmission multicast approach.     

Attempts to reduce the incidence of false recall with source monitoring.

In 5 experiments, the source-monitoring framework was applied to the Deese-Roediger-McDermott (DRM) paradigm, which has received so much interest recently. The authors' goal was to demonstrate that under certain conditions, when items in the DRM paradigm were learned from more than 1 origin, the incidence of false memories would decline. This result was obtained with internal–external reality monitoring conditions in free recall (Exps 1 and 3). With more confusable sources that required internal–internal or external–external discriminations, there was no reduction in false recall (Exps 2a and 4). In all experiments, participants were willing to assign an origin to their false memories, even when given an option to claim that they were not sure of its source (Exp 2b). The results are discussed in terms of how source-monitoring principles can sometimes reduce false memories in the DRM paradigm. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effect of weaning and dietary galactose supplementation on digesta glycoproteins in pigs

Changes in pig digesta mucin and glycoprotein content at weaning and with the inclusion of galactose in the postweaning diet were studied. Mucus was collected from ileal contents of cannulated pigs pre‐ and postweaning, and glycoproteins were analysed based on staining patterns and size exclusion chromatography. An increased concentration of intestinal mucin in lumen contents was observed in newly weaned pigs compared to the same pigs prior to weaning. Analysis of O‐linked oligosaccharides indicated changes in mucin structure from pre‐ to postweaning. Supplementing the diet with galactose resulted in modification of mucin in postweaned pigs compared to a control diet and may limit microbial degradation of mucin. These data indicate that weaning and the subsequent transition to a grain‐based diet result in changes to digesta mucin and endogenous glycoproteins; and dietary galactose may play a role in the final composition and quantity of these compounds. © 2000 Society of Chemical Industry     

Stability of ceramic color reflectance standards

This article reviews the long-term repeatability of spectrophotometric color measurements of ceramic color standards calibrated by Hemmendinger Color Laboratory (HCL) since it was founded 25 years ago. A set of twelve BCRA tiles was measured at HCL in 1977, and a few months later at NBS. The CIELAB color-difference, averaged over the twelve tiles, between HCL and NBS was 0.25 units. Measured at HCL about every four months since that time, the repeatability of measurement, averaged over the twelve tiles, has been better than 0.15 CIELAB units. The difference from the NBS measurements has remained at about 0.25 units over two decades. From these data the conclusion can be drawn that the tiles have not changed color during this period of time by an amount exceeding the limits of instrumental repeatability, namely about 0.15 units. © 1998 John Wiley & Sons, Inc. Col Res Appl, 23: 408–415, 1998