3,280 research outputs found
Can One See the Number of Colors?
We formulate the standard model with an arbitrary number of colors N_c. The
cancellation of Witten's global SU(2)_L anomaly requires N_c to be odd, while
the cancellation of triangle anomalies determines the consistent N_c-dependent
values of the quark charges. In this theory, the width of the neutral pion
decay into two photons is not proportional to (N_c)^2. In fact, in the case of
a single generation and hence for two quark flavors (N_f = 2), N_c does not
appear explicitly in the low-energy effective theory of the standard model.
Hence, contrary to common lore, it is impossible to see the number of colors in
low-energy experiments with just pions and photons. For N_f > 2, on the other
hand, N_c explicitly enters the chiral Lagrangian as the quantized prefactor of
the Wess-Zumino-Witten term, but the contribution of this term to photon-pion
vertices is completely canceled by the N_c-dependent part of a
Goldstone-Wilczek term. However, the width of the eta decay into pi^+ pi^-
gamma survives the cancellation and is indeed proportional to (N_c)^2. By
detecting the emerging photon, this process thus allows one to literally see
N_c for N_f > 2.Comment: 24 pages, no figures, Late
AEGIS: Agent oriented organisations
Today's enterprises are faced with highly dynamic, sometimes even hostile environments. This paper dicovers that the two most prominent organizational strategies addressing these challenges, namely that of widespread decentralization and of business process orientation, are inherently conflicting. We argue that cooperative knowledge processing technology can contribute to dissolve this conflict. For this purpose, we introduce the reader into the field of Distributed Artificial Intelligence. On that basis we then develop the concept of Agent oriEnted orGanISations (AEGIS), in order to support the flexible modeling and management of business processes in decentralized organizational settings. Applying to methods of Distributed Planning a set of process modeling and process interaction operators is defined. These operators also permit to automatically create and customize computerized configurations of business processes. The concepts are presented in the context of an application in private banking, namely that of a Credit Advisory System
Investigation of para-sulfonatocalix[n]arenes [n = 6, 8] as potential chelates for 230U
International audienceLiterature reports of the efficacy of para-sulfonatocalix[6]- and calix[8]-arenes as U(VI) complexants indicated that they might be useful for in vivo chelation of the novel therapeutic alhpa-emitter 230U. We have studied the complexation of U(VI) with para-sulfonatocalix[6]arene and para-sulfonatocalix[8]arene by time resolved laser induced fluorescence spectroscopy and using competition methods with Chelex resin and 4-(2-pyridylazo)resorcinol in simplified and in biological media. New thermodynamic parameters describing the stability of U(VI)-para-sulfonatocalix[n]arene [n = 6, 8] complexes were obtained. Although the interactions are strong, the complexes do not exhibit sufficient stability to compete with carbonate ions and serum proteins for complexation of U(VI) under physiological conditions
AEGIS:Agent oriEnted orGanISations
Today's enterprises are faced with highly dynamic, sometimes even hostile environments. This paper dicovers that the two most prominent organizational strategies addressing these challenges, namely that of widespread decentralization and of business process orientation, are inherently conflicting. We argue that cooperative knowledge processing technology can contribute to dissolve this conflict. For this purpose, we introduce the reader into the field of Distributed Artificial Intelligence. On that basis we then develop the concept of Agent oriEnted orGanISations (AEGIS), in order to support the flexible modeling and management of business processes in decentralized organizational settings. Applying to methods of Distributed Planning a set of process modeling and process interaction operators is defined. These operators also permit to automatically create and customize computerized configurations of business processes. The concepts are presented in the context of an application in private banking, namely that of a Credit Advisory System.<br
Silencing of MBD1 and MeCP2 in prostate-cancer-derived PC3 cells produces differential gene expression profiles and cellular phenotypes
Alterations in genomic CpG methylation patterns have been found to be associated with cell transformation and neoplasia. Although it is recognized that methylation of CpG residues negatively regulates gene expression, how the various MBPs (methyl-binding proteins) contribute to this process remains elusive. To determine whether the two well characterized proteins MeCP2 (methyl-CpG-binding protein 2) and MBD1 (methyl-CpG-binding domain 1) have distinct or redundant functions, we employed RNAi (RNA interference) to silence their expression in the prostate cancer-derived PC3cell line, and subsequently compared cell growth, invasion and migration properties of these cell lines in addition to their respective mRNA-expressionprofiles. Cells devoid of MeCP2 proliferated more poorly compared with MBD1-deficient cells and the parental PC3 cells. Enhanced apoptosis was observed in MeCP2-deficient cells, whereas apoptosis in parental and MBD1-deficient cells appeared to be equivalent. Boyden chamber invasion and wound-healing migration assays showed that MBD1-silenced cells were both more invasive and migratory compared with MeCP2-silenced cells. Finally, gene chip microarray analyses showed striking differences in the mRNA-expression profiles obtained from MeCP2- and MBD1-depleted cellsrelative to each other as well as when compared with control cells. The results of the present study suggest that MeCP2 and MBD1 silencing appear to affect cellular processes independently in vivo and that discrete sets of genes involved in cellular proliferation, apoptosis, invasion and migration are targeted by each protein
NPARSEC : NTT Parallaxes of Southern Extremely Cool objects. Goals, targets, procedures and first results
The discovery and subsequent detailed study of T dwarfs have provided many surprises and pushed the physics and modelling of cool atmospheres in unpredicted directions. Distance is a critical parameter for studies of these objects to determine intrinsic luminosities, test binarity and measure their motion in the Galaxy. We describe a new observational programme to determine distances across the full range of T-dwarf subtypes using the New Technology Telescope (NTT)/SOFI telescope/instrument combination. We present preliminary results for ten objects, five of which represent new distances.Peer reviewe
Education to Educate: A Case of Punjab Education Foundation
Mrs. Shehzad's doorbell rang, and she came out to open the door. She was sure about the arrival of her children Ali and Sana on the door as it was the time of school closing at 3'o clock. While serving the lunch, she thanked Allah and recalled the time a few years back. When Ali was in 4th grade, and Sana was in 5th grade, Mr. & Mrs. Shahzad thought to change the school of their children from private to government. This thought emerged because they were unable to afford the fee schedule of private schools. But they were aware of the drawbacks of Government Schools too. They never wanted to abolish their children's confidence level, productivity, and learning. It was not the dilemma of one home but the whole nation
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