Three-Dimensional Unsteady Flow With Heat and Mass Transfer Over a Continuous Stretching Surface

A numerical solution of the unsteady boundary layer equations under similarity assumptions is obtained. The solution represents the three-dimensional unsteady fluid motion caused by the time-dependent stretching of a flat boundary. It has been shown that a self-similar solution exists when either the rate of stretching is decreasing with time or it is constant. Three different numerical techniques are applied and a comparison is made among them as well as with earlier results. Analysis is made for various situations like deceleration in stretching of the boundary, mass transfer at the surface, saddle and nodal point flows, and the effect of a magnetic field. Both the constant temperature and constant heat flux conditions at the wall have been studied.

Learning dynamic prices in multiseller electronic retail markets with price sensitive customers, stochastic demands, and inventory replenishments

In this paper, we use reinforcement learning (RL) as a tool to study price dynamics in an electronic retail market consisting of two competing sellers, and price sensitive and lead time sensitive customers. Sellers, offering identical products, compete on price to satisfy stochastically arriving demands (customers), and follow standard inventory control and replenishment policies to manage their inventories. In such a generalized setting, RL techniques have not previously been applied. We consider two representative cases: 1) no information case, were none of the sellers has any information about customer queue levels, inventory levels, or prices at the competitors; and 2) partial information case, where every seller has information about the customer queue levels and inventory levels of the competitors. Sellers employ automated pricing agents, or pricebots, which use RL-based pricing algorithms to reset the prices at random intervals based on factors such as number of back orders, inventory levels, and replenishment lead times, with the objective of maximizing discounted cumulative profit. In the no information case, we show that a seller who uses Q-learning outperforms a seller who uses derivative following (DF). In the partial information case, we model the problem as a Markovian game and use actor-critic based RL to learn dynamic prices. We believe our approach to solving these problems is a new and promising way of setting dynamic prices in multiseller environments with stochastic demands, price sensitive customers, and inventory replenishments.

A microspectroscopic study of the electronic homogeneity of ordered and disordered Sr2FeMoO6

Disordered Sr2FeMoO6 shows a drastic reduction in saturation magnetization compared to highly ordered samples, moreover magnetization as a function of the temperature for different disordered samples shows qualitatively different behaviours. We investigate the origin of such diversity by performing spatially resolved photoemission spectroscopy on various disordered samples. Our results establish that extensive electronic inhomogeneity, arising most probably from an underlying chemical inhomogeneity in disordered samples, is responsible for the observed magnetic inhomogeneity. It is further pointed out that these inhomogeneities are connected with composition fluctuations of the type Sr2Fe1+xMo1-xO6 with Fe-rich (x > 0) and Mo-rich (x < 0) regions.

Correlation between stick-slip frictional sliding and charge transfer

A decade ago, Budakian and Putterman [Phys. Rev. Lett. 85, 1000 (2000)] ascribed friction to the formation of bonds arising from contact charging when a gold tip of a surface force apparatus was dragged on polymethylmethacrylate surface. We propose a stick-slip model that captures the observed correlation between stick-slip events and charge transfer, and the lack of dependence of the scale factor connecting the force jumps and charge transfer on normal load. Here, stick-slip dynamics arises as a competition between the viscoelastic and plastic deformation time scales and that due to the pull speed with contact charging playing a minor role. Our model provides an alternate basis for explaining most experimental results without ascribing friction to contact charging.

Spectroscopic, microscopic and first rheological investigations in charge-transfer interaction induced organogels

This article describes two-component charge-transfer interaction mediated organogels (CT-gels) derived from anthracene carboxamides obtained from 2-amino 2-hydroxymethyl-1,3-propanediol (TRIS), and 2,3-dialkoxyanthracenes as donors, with 2,4,7-trinitrofluorenone (TNF) as the common acceptor. We demonstrate the versatility of TNF as an electron acceptor in the formation of these gels. The effect of subtle changes in the donor structure on the gelation ability has been investigated by varying the alkyl chain length in the dialkoxyanthracene donors, and by varying the position of the TRIS substituent in the anthracene carboxamide donors. Distinct differences have been observed in the nature of the CT-gels based on these two kinds of anthracene donors. It has been reported in the literature that 2,3-dialkoxyanthracenes form gels on their own in various aliphatic hydrocarbons and alcohols for linear alkyl chains bearing at least 6mcarbon atoms (C-6). In the present study, it is shown that themCT-complex of these molecules with TNF is able to gel many alcoholic and a few hydrocarbon solvents. Also, in the presence of TNF, the 2,3-dialkoxyanthracenes (C-4-C-5) which were non-gelators on their own at ambient temperatures, form CT-gels in a number of alcohols. The other series of gelators discussed, the anthracene carboxamides, require the mandatory presence of TNF to form gels. This donor-acceptor complex forms gels in various aliphatic alcohols. Interestingly, the formation of these CT-gels requires rapid cooling in most of the cases. Thermal stability studies with both types of CT-gels indicate an optimum stoichiometry of 1 : 1 between the donor and the acceptor. Dynamic rheological experiments reveal these gels as viscoelastic soft materials, with the mechanical strength of these gels depending on the amount of TNF present. This provides a means to tune the strength of the gel by varying the doping concentration of the acceptor.

Publishing in the Networked World: Transforming the Nature of Communication, 14th International Conference on Electronic Publishing 16-18 June 2010, Helsinki, Finland

The title of the 14th International Conference on Electronic Publishing (ELPUB), “Publishing in the networked world: Transforming the nature of communication”, is a timely one. Scholarly communication and scientific publishing has recently been undergoing subtle changes. Published papers are no longer fixed physical objects, as they once were. The “convergence” of information, communication, publishing and web technologies along with the emergence of Web 2.0 and social networks has completely transformed scholarly communication and scientific papers turned to living and changing entities in the online world. The themes (electronic publishing and social networks; scholarly publishing models; and technological convergence) selected for the conference are meant to address the issues involved in this transformation process. We are pleased to present the proceedings book with more than 30 papers and short communications addressing these issues. What you hold in your hands is a by-product and the culmination of almost a Year long work of many people including conference organizers, authors, reviewers, editors and print and online publishers. The ELPUB 2010 conference was organized and hosted by the Hanken School of Economics in Helsinki, Finland. Professors Turid Hedlund of Hanken School of Economics and Yaşar Tonta of Hacettepe University Department of Information Management (Ankara, Turkey) served as General Chair and Program Chair, respectively. We received more than 50 submissions from several countries. All submissions were peer-reviewed by members of an international Program Committee whose contributions proved most valuable and appreciated. The 14th ELPUB conference carries on the tradition of previous conferences held in the United Kingdom (1997 and 2001), Hungary (1998), Sweden (1999), Russia (2000), the Czech Republic (2002), Portugal (2003), Brazil (2004), Belgium (2005), Bulgaria (2006), Austria (2007), Canada (2008) and Italy (2009). The ELPUB Digital Library, http://elpub.scix.net serves as archive for the papers presented at the ELPUB conferences through the years. The 15th ELPUB conference will be organized by the Department of Information Management of Hacettepe University and will take place in Ankara, Turkey, from 14-16 June 2011. (Details can be found at the ELPUB web site as the conference date nears by.) We thank Marcus Sandberg and Hannu Sääskilahti for copyediting, Library Director Tua Hindersson – Söderholm for accepting to publish the online as well as the print version of the proceedings. Thanks also to Patrik Welling for maintaining the conference web site and Tanja Dahlgren for administrative support. We warmly acknowledge the support in organizing the conference to colleagues at Hanken School of Economics and our sponsors.

Synthesis of both enantiomers of 1-phenylethane-1,2-diol via chirality transfer from bile acid derivatives

Both enantiomers of 1-phenylethane-1,2-diol were synthesized with good to excellent enantioselectivities via selective reduction of the phenylglyoxalates derived from bile acids, followed by reductive cleavage. (C) 2000 Elsevier Science Ltd. All rights reserved.

Electronic structure of high-Tc superconductors from core-level spectroscopies

Using the configuration-interaction approach, we show that various core-level spectroscopic observations on the high-Tc superconducting oxides can be consistently described in terms of mixing between d9 and d10 configurations, with a negligible amount of the d8 (Cu3+) state. From our analysis of the existing experimental data, we provide evidence of a wide and continuous valence transition in these systems as a function of temperature. The changes in the hybridization strengths deduced here are indicative of structural modifications of the square-planar CuO4 clusters with decreasing temperature.

Electronic structure of square planar CuO46− clusters

The results of spin-polarized MSXagr calculations show that the ground state of the CuO 4 6– cluster is essentially non-magnetic in spite of odd number of electrons in the system for short Cu–O distances (1.90 Å) as found in the highT c superconductors. This arises due to the fact that the unpaired electron resides in a molecular orbital with primarily oxygen 3s character. The stability of this molecular orbital is found to be sensitive to the cluster geometry and thus, increase in Cu–O distance (as well as other changes affecting oxygen-oxygen distance) tend to favour a magnetic state. From these calculations we have also estimated the Coulomb correlation strength within the Cu 3d to be about 5.3 eV.

Interrelations between Dry Eye Syndrome and Tear Fluid Phospholipid Transfer Protein

The simplified model of human tear fluid (TF) is a three-layered structure composed of a homogenous gel-like layer of hydrated mucins, an aqueous phase, and a lipid-rich outermost layer found in the tear-air interface. It is assumed that amphiphilic phospholipids are found adjacent to the aqueous-mucin layer and externally to this a layer composed of non-polar lipids face the tear-air interface. The lipid layer prevents evaporation of the TF and protects the eye, but excess accumulation of lipids may lead to drying of the corneal epithelium. Thus the lipid layer must be controlled and maintained by some molecular mechanisms. In the circulation, phospholipid transfer protein (PLTP) and cholesteryl ester transfer protein (CETP) mediate lipid transfers. The aim of this thesis was to investigate the presence and molecular mechanisms of lipid transfer proteins in human TF. The purpose was also to study the role of these proteins in the development of dry eye syndrome (DES). The presence of TF PLTP and CETP was studied by western blotting and mass spectrometry. The concentration of these proteins was determined by ELISA. The activities of the enzymes were determined by specific lipid transfer assays. To study the molecular mechanisms involved in PLTP mediated lipid transfer Langmuir monolayers and asymmetrical flow field-flow fractionation (AsFlFFF) was used. Ocular tissue samples were stained with monoclonal antibodies against PLTP to study the secretion route of PLTP. Heparin-Sepharose affinity chromatography was used for PLTP pull-down experiments and co-eluted proteins were identified with MALDI-TOF mass spectrometry or Western blot analysis. To study whether PLTP plays any functional role in TF PLTP-deficient mice were examined. The activity of PLTP was also studied in dry eye patients. PLTP is a component of normal human TF, whereas CETP is not. TF PLTP concentration was about 2-fold higher than that in human plasma. Inactivation of PLTP by heat treatment or immunoinhibition abolished the phospholipid transfer activity in tear fluid. PLTP was found to be secreted from lacrimal glands. PLTP seems to be surface active and is capable of accepting lipid molecules without the presence of lipid-protein complexes. The active movement of radioactively labeled lipids and high activity form of PLTP to acceptor particles suggested a shuttle model of PLTP-mediated lipid transfer. In this model, PLTP physically transports lipids between the donor and acceptor. Protein-protein interaction assays revealed ocular mucins as PLTP interaction partners in TF. In mice with a full deficiency of functional PLTP enhanced corneal epithelial damage, increased corneal permeability to carboxyfluorescein, and decreased corneal epithelial occludin expression was demonstrated. Increased tear fluid PLTP activity was observed among human DES patients. These results together suggest a scavenger property of TF PLTP: if the corneal epithelium is contaminated by hydrophobic material, PLTP could remove them and transport them to the superficial layer of the TF or, alternatively, transport them through the naso-lacrimal duct. Thus, PLTP might play an integral role in tear lipid trafficking and in the protection of the corneal epithelium. The increased PLTP activity in human DES patients suggests an ocular surface protective role for this lipid transfer protein.

Studies on transfer RNA from mycobacteria

Active preparations of tRNA and aminoacyl-tRNA synthetases have been isolated from exponentially growing cells of Mycobacterium smegmatis and Mycobacterium tuberculosis H37Rv. Though the aminoacyl-tRNA synthetases of older cells retain their activity, the tRNAs seem to undergo modification and show poorer activity. The mycobacterial enzyme preparations catalyse homologous and heterologous aminoacylation between tRNA from the two species (M. smegmatis and M. tuberculosis H37Rv) or from Escherichia coli, with equal efficiency; tRNA samples from eukaryotic cells (yeast and rat liver) do not serve as substrates for the mycobacterial synthetases. The analytical separation of the different amino acid specific tRNAs from M. smegmatis resembles the pattern found in other bacteria. Purification of valine- (three species) and methionine-specific tRNA (two species) to 70-80% purity has been accomplished by using column-chromatographic techniques. Of the two species of tRNAMet, one can be formylated in the presence of formyl tetrahydrofolate and the transformylase from mycobacteria.