All twist and no bend makes raft edges splay: Spontaneous curvature of domain edges in colloidal membranes.

Using theory and experiments, we study the interface between two immiscible domains in a colloidal membrane composed of rigid rods of different lengths. Geometric considerations of rigid rod packing imply that a domain of sufficiently short rods in a background membrane of long rods is more susceptible to twist than the inverse structure, a long-rod domain in a short-rod membrane. The midplane tilt at the interdomain edge forces splay, which, in turn, manifests as spontaneous edge curvature with energetics controlled by the length asymmetry of constituent rods. A thermodynamic model of such tilt-curvature coupling at interdomain edges explains a number of experimental observations, including annularly shaped long-rod domains, and a nonmonotonic dependence of edge twist on domain radius. Our work shows how coupling between orientational and compositional degrees of freedom in two-dimensional fluids gives rise to complex shapes of fluid domains, analogous to shape transitions in 3D fluid vesicles.

Electronic procedure logs: taking it further.

OBJECTIVE: To create an electronic procedural logbook with enhanced user interactivity and usefulness as an educational resource. DESCRIPTION: From our own work on electronic student logbooks and other studies, it is clear that compliance with complete and valid data entry remains a challenge. Without direct and visible benefit, students are reluctant to spend time logging all their cases. We developed an interactive procedural logbook using Microsoft Embedded Visual Basic and Metrowerks CodeWarrior. Interface design focused on rapid data entry with minimum requirement for text, and field-level automation where possible. We loaded it onto a mixed platform of personal digital assistants (PDAs)--Compaq iPaq Pocket PCs and HandEra 330 PalmOS devices. Our rural residents were supplied with the devices of their choice. Various built-in educational reference resources included: (1) contextual help options about each procedure, which contained diagrams and pictures; (2) diagnostic and fee coding so they could see how poorly some procedures pay; and (3) Quick Tips relevant to each procedure, which can be easily modified by the preceptor. Preceptor evaluations and comments can be entered rapidly. Using built-in database conduits, data are automatically collected from each device on every HotSync with the desktop. Data can then be collated and analyzed using Microsoft Access or via secure Web access. DISCUSSION: Improved compliance has been dramatic-one resident logged 250 procedures in just two months. However, not all residents have been successful in establishing seamless synchronization, and the resulting data loss has caused frustration. The evidence indicates the need to implement central data collection and backup right from the outset. Central data collection provides many advantages. The program director has better information for future applications. Preceptor evaluations are now spread over many interactions and yet can be collated and analyzed. Quick Tips have been very popular-we have been able to collect the tips and redistribute them. Focus-group feedback from the residents has shown that the rich data in the logbook's reference component improved its usefulness and popularity as an educational tool. Choice of device type is important for user acceptance because devotees of one platform are reluctant to switch to another. Cross-platform development does slow the process but is increasingly easy with the latest software design tools, such as AppForge. These new tools have enabled us to explore further improvements in data entry. Digital ink provides the ability to capture annotated diagrams and preceptor signatures. Voice input is built in with these devices, and our software now allows for voice annotation for more detailed commentary by preceptors or student. The compressed digital sound file is collected along with the data and transcribed centrally (on-device voice recognition is not feasible yet). Point-of-care accessibility has been the key attraction of using these devices for logging encounter data. This project demonstrates that it is important to explore all multimodal interactive capabilities to provide a truly rich educational tool.

Alternative splicing of the Vupur3 transcript in cowpea produces multiple mRNA species with a single protein product that is present in both plastids and mitochondria.

A heterogeneous population of cDNAs (designated Vupur3) encoding phosphoribosylglycinamide formyltransferase (GART; EC 2.1.2.2) was isolated from a cowpea (Vigna unguiculata L. Walp.) nodule library. Three classes of cDNA with the same ORF, but differing in their 3'-UTRs, were identified. Southern analysis and sequencing of genomic DNA confirmed that these differences result from alternative splicing of the primary transcript of a single Vupur3 gene. Alternative splicing does not appear to play a role in the production of soybean (Glycine max Merrill.) pur3 transcripts. The presence of the protein product of the Vupur3 gene, GART, in plastids and mitochondria was confirmed by immunoblotting with antibodies raised against the recombinant protein. The antibodies recognised two proteins with apparent molecular masses of 27 and 27.5 kDa in both mitochondria and plastids. All Vupur3 transcripts have two in-frame start codons that are active in wheatgerm in vitro transcription / translation experiments suggesting a mechanism by which the gene product could be targeted to two organelles. Like other genes encoding enzymes for purine synthesis, Vupur3 is expressed in nodules before nitrogen fixation begins but in contrast to these genes its expression does not increase markedly after nitrogen fixation begins.