Chiral auxiliaries in polymer-supported organic synthesis

The use of chiral auxiliaries in polymer-supported organic synthesis is reviewed. In many of the examples presented, not only does the auxiliary serve as an element for inducing asymmetry into the synthesis, but it also functions as the linker for attaching the synthesis substrate to the polymer support. © 2003 Elsevier Ltd. All rights reserved.postprin

A polystyrene-supported triflating reagent for the synthesis of aryl triflates

An insoluble polystyrene-supported triflating reagent has been prepared by suspension co-polymerization of N-(4-vinylphenyl)trifluoromethanesulphonimide, styrene and the JandaJel ® cross-linker. This reagent, in the presence of triethylamine, allows for the efficient synthesis of aryl triflates from a wide range of phenols in a process that permits the desired product to be isolated from the reaction mixture in essentially pure form via several filtration and concentration operations. Adding to the utility of this reagent is its ability to be easily recovered, regenerated and reused. Both soluble and insoluble bifunctional polymers containing trialkylamine moieties in addition to triflimide groups were also prepared and examined as triflating reagents. Unfortunately these reagents afforded only modest yields of the desired products in representative reactions. Graphical Abstract. © 2004 Elsevier Ltd. All rights reserved.postprin

The Sikh Gurmat sangīt revival in post-partition India

textGurmat sangīt, literally sacred music of the Sikhs, is a religious marker of Sikhism. Sikh religious practice is oriented toward musical performance to worship God and evoke spiritual elevation. As a common religious practice at the Sikh temples, gurmat sangīt generally involves recitation of religious texts and devotional singing with instrumental accompaniment by professional musicians and/or the congregation. It also illustrates musical ways of uniting with God as found in Sikh scriptures. The major sacred text, the Guru Granth Sahib, contains a large number of verses in an arrangement organized by rāgas (musical modes). Gurmat sangīt has developed rapidly since the 1980s. The number of recordings, publications, and performances featuring Sikh religious music and/or musicians increased. Academic programs and organizations of gurmat sangīt were launched to train both professional and amateur musicians in India and abroad. At that time, a trend has developed to revive the authentic practice of Sikh devotional music with correct rendition of rāga performance and the re-introduction of stringed instruments such as the tāūs (a bowed-string instrument in peacock body sound box) and rabāb (a plucked-lute instrument). While exhibiting a tendency to standardize musical details and generate a historiography of Sikh music, contemporary practitioners also emphasize authenticity and tradition in re-imagining the devotional music performance at the time of the Sikh Gurūs. The revival is identified with not only professional Sikh musicians in Punjab but also overseas Sikh musicians and musicians of other religious and/or socio-cultural backgrounds. In this study, I adopt the case study approach to examine the phenomenon of the gurmat sangīt revival in 20th- and 21st-century Punjab. My research focuses on the annual performances of Sikh devotional music, and a Sikh religious institution in the city of Ludhiana, from where the trend of the music revival has been developed. For the revival’s aim to promote the “authentic” Sikh devotional music tradition, I argue that it involves a self-interpretation of combined authentic, invented, and westernized concepts in association with musical practice at the Sikh Gurūs’ times and Indian classical music, and being shown in the standardization, classicization, and hybridization of Sikh devotional music performance.Musi

Arsonium ylides in organic synthesis

postprin

Water extract of Rheum officinale Baill. induces apoptosis in human lung adenocarcinoma A549 and human breast cancer MCF-7 cell lines

Author name used in this publication: De-Jian GuoAuthor name used in this publication: Peter Hoi-Fu Yu2009-2010 > Academic research: refereed > Publication in refereed journalAccepted ManuscriptPublishe

Acquired trichostasis in postoperative site: a case report

This is an Open Access article distributed under the terms of the Creative Commons Attribution Licens

A Scintillating Fiber Tracker With SiPM Readout

We present a prototype for the first tracking detector consisting of 250 micron thin scintillating fibers and silicon photomultiplier (SiPM) arrays. The detector has a modular design, each module consists of a mechanical support structure of 10mm Rohacell foam between two 100 micron thin carbon fiber skins. Five layers of scintillating fibers are glued to both top and bottom of the support structure. SiPM arrays with a channel pitch of 250 micron are placed in front of the fibers. We show the results of the first module prototype using multiclad fibers of types Bicron BCF-20 and Kuraray SCSF-81M that were read out by novel 32-channel SiPM arrays from FBK-irst/INFN Perugia as well as 32-channel SiPM arrays produced by Hamamatsu. A spatial resolution of 88 micron +/- 6 micron at an average yield of 10 detected photons per minimal ionizig particle has been achieved.Comment: 5 pages, 7 figures, submitted as proceedings to the 11th Topical Seminar on Innovative Particle and Radiation Detectors (IPRD08

Markov Chain Methods For Analyzing Complex Transport Networks

We have developed a steady state theory of complex transport networks used to model the flow of commodity, information, viruses, opinions, or traffic. Our approach is based on the use of the Markov chains defined on the graph representations of transport networks allowing for the effective network design, network performance evaluation, embedding, partitioning, and network fault tolerance analysis. Random walks embed graphs into Euclidean space in which distances and angles acquire a clear statistical interpretation. Being defined on the dual graph representations of transport networks random walks describe the equilibrium configurations of not random commodity flows on primary graphs. This theory unifies many network concepts into one framework and can also be elegantly extended to describe networks represented by directed graphs and multiple interacting networks.Comment: 26 pages, 4 figure

Single antenna interference cancellation in asynchronous GSM/GPRS networks

Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2005.Includes bibliographical references (p. 73-74).In this project, we have proposed a decorrelator-based single antenna interference cancellation algorithm for the asynchronous GSM/GPRS network. The algorithm is tested according to the current SAIC/DARP performance requirement in the computer simulation, and is shown to give various gains in different test scenarios.by Chung Chan.M.Eng

Generating secret in a network

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2010.Cataloged from PDF version of thesis.Includes bibliographical references (p. 247-253) and index.This monograph studies the theory of information through the multiuser secret key agreement problem. A general notion of mutual dependence is established for the secrecy capacity, as a natural generalization of Shannon's mutual information to the multivariate case. Under linear-type source models, this capacity can be achieved practically by linear network codes. In addition to being an unusual application of the network coding solution to a secrecy problem, it gives secrecy capacity an interpretation of network information flow and partition connectivity, further confirming the intuitive meaning of secrecy capacity as mutual dependence. New identities in submodular function optimization and matroid theory are discovered in proving these results. A framework is also developed to view matroids as graphs, allowing certain theory on graphs to generalize to matroids. In order to study cooperation schemes in a network, a general channel model with multiple inputs is formulated. Single-letter secrecy capacity upper bounds are derived using the Shearer-type lemma. Lower bounds are obtained with a new cooperation scheme called the mixed source emulation. In the same way that mixed strategies may surpass pure strategies in zero-sum games, mixed source emulation outperforms the conventional pure source emulation approach in terms of the achievable key rate. Necessary and sufficient conditions are derived for tightness of these secrecy bounds, which shows that secrecy capacity can be characterized for a larger class of channels than the broadcast-type channels considered in previous work. The mixed source emulation scheme is also shown to be unnecessary for some channels while insufficient for others. The possibility of a better cooperative scheme becomes apparent, but a general scheme remains to be found.by Chung Chan.Ph.D