Developing methods to understand discourse and workspace in distributed computer-mediated interaction

This paper presents ongoing research towards understanding the discourse and workspace in computer-mediated interactions. We present a series of methods developed to study non-collocated computer-mediated interactions. These methods were developed originally to study interactions involving teams composed of architecture, engineering, and construction management students as part of the AEC Global Teamwork course offered at Stanford University in collaboration with universities worldwide since 1993. The methods stress the value of using ethnographic approaches, particularly the role that both discourse and workspace have in developing the communication processes involved in the interactions. We used the AEC Global Teamwork course as a testbed and focused on issues regarding the nature of the communication act in building design projects when mediated by computers. We successfully tested these new methods and present the preliminary results.

Pharmacophore design and database searching for selective monoamine neurotransmitter transporter ligands

Neuronal monoamine transporters (MATs) are involved in the pathophysiology and treatment of mental health conditions such as depression, attention deficit hyperactivity disorder, substance abuse and neurodegenerative disorders including Alzheimer's disease and Parkinson's disease. Various structural classes of compounds have been synthesized and tested in vitro for activity against transporters of three monoamine signaling molecules: noradrenaline (NET); serotonin (SERT) and dopamine (DAT). We have developed and validated a number of pharmacophore models describing the interaction of two classes of compounds with each of these three MATs. These pharmacophores explain the selectivity of binding to the MATs for various compound classes and have been used to search in silico databases for novel, potentially selective ligands. These ligands, after confirmation of their activities, will provide tools for investigating the function of MATs as well as the potential for new therapeutic agents in mental health applications. The database searches also retrieved close analogues of known MAT ligands, further validating the approach.     

Reactive processing of PA6/EPDM-MA blends as modifier for application and development of high-performance polypropylene

In this work, PA6/EPDM-MA was added as an impact modifier for high-performance polypropylene (PP) production. PA6/EPDM-MA compounds were processed in an internal mixer, aiming at chemical reaction between maleic anhydride of EPDM-MA and the amine terminal groups of PA6. Afterward, PP/(PA6/EPDM-MA) blends were processed by extrusion and injection molding. Rheological properties were evaluated using torque rheometry; additionally, Fourier transform infrared spectroscopy, Molau test, impact and tensile strengths, Shore D hardness, thermal deflection temperature, X-ray diffraction, differential scanning calorimetry, thermogravimetry, water absorption, contact angle, and scanning electron microscopy tests were performed in injected specimens. PP/(PA6/EPDM-MA) with 70/(15/15)% displayed quite high increase in impact and elongation at break, with gains of 850% and 265%, compared to neat PP. There were no drastic losses in tensile strength, elastic modulus, and Shore D hardness, due to PA6 addition. A significant increase was seen in the thermal stability of PP/(PA6/EPDM-MA), corroborating the increase in structural stability seen in HDT. SEM images showed high interfacial adhesion between PP and PA6/EPDM-MA corroborating higher mechanical properties. Summing up, PA6/EPDM-MA premix acted as an efficient impact modifier for PP. Acquired data show that P6/EPDM-MA system was effective in developing high-performance PP with potential for application in the automotive and electronics industries.     

Adaptive rejection Metropolis sampling using Lagrange interpolation polynomials of degree 2

A crucial problem in Bayesian posterior computation is efficient sampling from a univariate distribution, e.g. a full conditional distribution in applications of the Gibbs sampler. This full conditional distribution is usually non-conjugate, algebraically complex and computationally expensive to evaluate. We propose an alternative algorithm, called ARMS2, to the widely used adaptive rejection sampling technique ARS [Gilks, W.R., Wild, P., 1992. Adaptive rejection sampling for Gibbs sampling. Applied Statistics 41 (2), 337-348; Gilks, W.R., 1992. Derivative-free adaptive rejection sampling for Gibbs sampling. In: Bernardo, J.M., Berger, J.O., Dawid, A.P., Smith, A.F.M. (Eds.), Bayesian Statistics, Vol. 4. Clarendon, Oxford, pp. 641-649] for generating a sample from univariate log-concave densities. Whereas ARS is based on sampling from piecewise exponentials, the new algorithm uses truncated normal distributions and makes use of a clever auxiliary variable technique [Damien, P., Walker, S.G., 2001. Sampling truncated normal, beta, and gamma densities. Journal of Computational and Graphical Statistics 10 (2) 206-215]. Furthermore, we extend this algorithm to deal with non-log-concave densities to provide an enhanced alternative to adaptive rejection Metropolis sampling, ARMS [Gilks, W.R., Best, N.G., Tan, K.K.C., 1995. Adaptive rejection Metropolis sampling within Gibbs sampling. Applied Statistics 44, 455-472]. The performance of ARMS and ARMS2 is compared in simulations of standard univariate distributions as well as in Gibbs sampling of a Bayesian hierarchical state-space model used for fisheries stock assessment.     

A contribution to the dispute on the Ortega hypothesis: Connection between publication rate and stratification of scientists,tested by various methods

It was tested whether the publication rate of scientists as a rough measure of their eminence, influences their stratification. The stratification is reflected in cooperation, in co-authorships, in the structure of the citations and in the distribution of publications among the various problem areas of a scientific discipline. The findings of these investigations was discussed as a contribution to the dispute among authors who accept or reject the Ortega hypothesis which states that the research done by average scientists substantially contributes to the advance of science.Some discussion papers abont the Ortega hypothesis were published in Scientometrics, 12 (1987) 293–353.     

Increased proteolytic resistance of ribonuclease A by protein engineering

Although highly stable toward unfolding, native ribonucleaseA is known to be cleaved by unspecific proteases in the flexibleloop region near Ala20. With the aim to create a protease-resistantribonuclease A, Ala20 was substituted for Pro by site-directedmutagenesis. The resulting mutant enzyme was nearly identicalto the wild-type enzyme in the near-UV and far-UV circular dichroismspectra, in its activity to 2',3'-cCMP and in its thermodynamicstability. However, the proteolytic resistance to proteinaseK and subtilisin Carlsberg was extremely increased. Pseudo-first-orderrate constants of proteolysis, determined by densitometric analysisof the bands of intact protein in SDS–PAGE, decreasedby two orders of magnitude. In contrast, the rate constant ofproteolysis with elastase was similar to that of the wild-typeenzyme. These differences can be explained by the analysis ofthe fragments occurring in proteolysis with elastase. Ser21–Ser22was identified as the main primary cleavage site in the degradationof the mutant enzyme by elastase. Obviously, this bond is notcleavable by proteinase K or subtilisin Carlsberg. The resultsdemonstrate the high potential of a single mutation in proteinstabilization to proteolytic degradation.     

Projection in surrogate decisions about life-sustaining medical treatments.

To honor the wishes of an incapacitated patient, surrogate decision makers must predict the treatment decisions patients would make for themselves if able. Social psychological research, however, suggests that surrogates' own treatment preferences may influence their predictions of others' preferences. In 2 studies (1 involving 60 college student surrogates and a parent, the other involving 361 elderly outpatients and their chosen surrogate decision maker), surrogates predicted whether a close other would want life-sustaining treatment in hypothetical end-of-life scenarios and stated their own treatment preferences in the same scenarios. Surrogate predictions more closely resembled surrogates' own treatment wishes than they did the wishes of the individual they were trying to predict. Although the majority of prediction errors reflected inaccurate use of surrogates' own treatment preferences, projection was also found to result in accurate prediction more often than counterprojective predictions. The rationality and accuracy of projection in surrogate decision making is discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Tethered bimolecular lipid membranes—A novel model membrane platform

This contribution summarizes some of our efforts in designing, synthesizing, assembling, and characterizing functional tethered bimolecular lipid membranes (tBLMs) as a novel platform for biophysical studies of and with artificial membranes or for sensor development employing, e.g., membrane integral receptor proteins. Chemical coupling schemes based on thiol groups for Au substrates or silanes used in the case of oxide surfaces allow for the covalent and, hence, chemically and mechanically robust attachment of anchor lipids to the solid support, stabilizing the proximal layer of a tethered membrane on the transducer surface. Surface plasmon optics, the quartz crystal microbalance, fluorescence- and IR spectroscopies, and electrochemical techniques are used to characterize the build-up of these complex supramolecular interfacial architectures. We demonstrate, in particular, that bilayers with a specific electrical resistance of better than 10 MΩ cm² can be achieved routinely with this approach.The functionalization of the lipid membranes by the incorporation of peptides is demonstrated for the carrier valinomycin which shows in our tBLMs the expected discrimination by four orders of magnitude between the translocation of K⁺- and Na⁺-ions across the hydrophobic barrier. For the synthetic channel-forming peptide M2 the high electrical resistance of the bilayer with the correspondingly low background current allows for the recording of even single channel current fluctuations.From the many membrane proteins that we reconstituted so far we describe results obtained with the redox-protein cytochrome c oxidase. Here, we also use a genetically modified mutant with a His-tag at either the C- or the N-terminus for the oriented attachment of the protein via the NTA/Ni²⁺ approach. With this strategy, we not only can control the density of the immobilized functional units, we introduce a completely new and alternative concept for the stabilization of lipid bilayers, i.e., the protein-tethered membrane.Our efforts in experimentally characterizing the resulting membrane functions and correlating the data with the structural details of the bilayer architectures are complemented by theoretical studies modeling the electrical and electrochemical response of functional tethered lipid bilayer membranes by extended SPICE simulations.