Crystal structure of bis-[3-meth-oxy-17β-estra-1,3,5(10)-trien-17-yl] oxalate.

In the title compound, C40H50O6, a symmetrical steroid oxalate diester, the dihedral angle between the CO2 planes of the oxalate linker is 61.5 (5)° and the C-C bond length is 1.513 (6) Å. The steroid B, C and D rings adopt half-chair, chair and envelope conformations, respectively, in both halves of the mol-ecule, which adopts an overall shallow V-shaped conformation. In the crystal, mol-ecules are linked by weak C-H⋯O inter-actions, forming a three-dimensional network

Designer requirements for visual capability loss simulator tools: Differences between design disciplines

There is a low uptake of inclusive design tools in industry, partly due to a poor fit between design tools and the thought and work processes of designers. Simulating visual capability losses is a technique with great potential in helping designers improve inclusivity and accessibility. However, we need to understand the needs of designers from different disciplines to improve the fit of these tools and their uptake in industry. This study aims to determine designers’ needs for vision loss simulators, and how this varies between disciplines. Interviews were carried out with 15 designers from five disciplines. The results suggest that one tool is not suitable for all. The graphic and web designers interviewed required a tool to aid communication with clients, hoever, the industrial and engineering designers required two tools, depending on the stage of the design process. To increase their uptake, simulator tools should be used in education.We would like to thank the EPSRC for funding this work, and Wolfson College Cambridge for their support.This is the author accepted manuscript. The final version is available from Springer via http://dx.doi.org/10.1007/978-3-319-07437-5_

Antimicrobial activities of secondary metabolites of endophytic fungi isolated from Catharanthus roseus

Introduction: Recently, several endophytes have been shown to possess the potentials to synthesize novel bioactive compounds that have found use for drug discovery. We isolated endophytic fungi associated with Catharanthus roseus collected from the river banks of Amassoma in Southern Nigeria, and identified some of their bioactive secondary metabolites. Methods: The fungi were subjected to solid-state fermentation on rice medium and the metabolites were extracted using ethyl acetate. The fungal crude extracts were screened for antimicrobial activity and were also subjected to high-performance liquid chromatography-diode-array detection (HPLC-DAD) analysis for the identification of the bioactive compounds. Results: The fungal extracts showed both antibacterial and antifungal activities with minimum inhibitory concentrations ranging from 0.0625 to 1 mg/mL. The HPLC-DAD analysis of the extracts suggested the presence of citreoisocoumarin, citreoisocoumarinol, questinol, hydroxyemodin, acropyrone, methyl 2-(4-hydroxyphenyl) acetate, nigricinol, and cladosporin. Conclusion: The results of this study suggest that endophytic fungi associated with C. roseus could be a promising source of novel bioactive compounds with pharmaceutical and industrial importance

The Use of Prior Knowledge in Learning from Examples

This dissertation examines the way people acquire procedures from examples, and provides a computational model of the results. In four experiments, people learned an analog of algebra. For each experiment, the initial know ledge that people had of the task was varied. In two experiments (Experiments 1 and 3), the syntactic know ledge that people had concerning the task w as manipulated. The knowledge of syntax that participants had, particularly the ability to correctly parse the character string, was found to be a major determiner in the way participants acquired the rules. Experiment 2 explicitly manipulated participant\u27s awareness as to how the task was related to their prior knowledge of algebra, with the finding that another major determiner of how the participants learned the task resting on how much of the task they can map to algebra. All three of these experiments examined the rule generalization behavior of the participants, with a fourth experiment specifically designed to examine this issue. The less syntactic and other declarative knowledge that participants had, the less general their rules. These findings, that people can learn from examples but that this learning is tempered by their additional declarative knowledge, are captured by an ACT-R model (Anderson, 1993)

Limits on WWgamma and WWZ Couplings from W Boson Pair Production

The results of a search for W boson pair production in pbar-p collisions at sqrt{s}=1.8 TeV with subsequent decay to emu, ee, and mumu channels are presented. Five candidate events are observed with an expected background of 3.1+-0.4 events for an integrated luminosity of approximately 97 pb^{-1}. Limits on the anomalous couplings are obtained from a maximum likelihood fit of the E_T spectra of the leptons in the candidate events. Assuming identical WWgamma and WWZ couplings, the 95 % C.L. limits are -0.62<Delta_kappa<0.77 (lambda = 0) and -0.53<lambda<0.56 (Delta_kappa = 0) for a form factor scale Lambda = 1.5 TeV.Comment: 10 pages, 1 figure, submitted to Physical Review

The African Political Business Cycle: Varieties of Experience

We seek to understand both the incidence and the impact of the African political business cycle in the light of a literature which has argued that, with major extensions of democracy since the 1990s, the cycle has both become more intense and has made African political systems more fragile. With the help of country-case studies, we argue, first, that the African political business cycle is not homogeneous, and occurs relatively infrequently in so-called ‘dominant-party systems’ where a pre-election stimulus confers little political advantage. Secondly, we show that, in those countries where a political cycle does occur, it does not necessarily cause institutional damage. Whether it does or not depends not so much on whether there is an electoral cycle as on whether this cycle calms or exacerbates fears of an unjust allocation of resources. In other words, the composition of the pre-election stimulus, in terms of its allocation between different categories of voter, is as important as its size

Epidermal Growth Factor–PEG Functionalized PAMAM-Pentaethylenehexamine Dendron for Targeted Gene Delivery Produced by Click Chemistry

Aim of this study was the site-specific conjugation of an epidermal growth factor (EGF)-polyethylene glycol (PEG) chain by click chemistry onto a poly(amido amine) (PAMAM) dendron, as a key step toward defined multifunctional carriers for targeted gene delivery. For this purpose, at first propargyl amine cored PAMAM dendrons with ester ends were synthesized. The chain terminal ester groups were then modified by oligoamines with different secondary amino densities. The oligoamine-modified PAMAM dendrons were well biocompatible, as demonstrated in cytotoxicity assays. Among the different oligoamine-modified dendrons, PAMAM-pentaethylenehexamine (PEHA) dendron polyplexes displayed the best gene transfer ability. Conjugation of PAMAM-PEHA dendron with PEG spacer was conducted via click reaction, which was performed before amidation with PEHA. The resultant PEG-PAMAM-PEHA copolymer was then coupled with EGF ligand. pDNA transfections in HuH-7 hepatocellular carcinoma cells showed a 10-fold higher efficiency with the polyplexes containing conjugated EGF as compared to the ligand-free ones, demonstrating the concept of ligand targeting. Overall gene transfer efficiencies, however, were moderate, suggesting that additional measures for overcoming subsequent intracellular bottlenecks in delivery have to be taken

Direct Search for Charged Higgs Bosons in Decays of Top Quarks

We present a search for charged Higgs bosons in decays of pair-produced top quarks in pbar p collisions at sqrt(s) = 1.8 TeV using 62.2 pb^-1 of data recorded by the D0 detector at the Fermilab Tevatron collider. No evidence is found for signal, and we exclude at 95% confidence most regions of the (M higgs, tan beta) parameter space where the decay t->H b has a branching fraction greater than 0.36 and B(H -> tau nu) is large.Comment: 11 pages, 4 figures, submitted to Phys. Rev. Let