Effects of scalar mixing ingg → Higgs → γγ

Zeitschrift für Physik C Particles and Fields - We discuss the effects of mixing of scalars belonging to left-and right-chiral MSSM super-multiplets on the processgg →h 0 →...     

Synthesis of (E)‐1,1‐Diethoxy‐3‐(3‐hydroxy‐3‐arylfuro[2,3‐b]quinoxalin‐2(3H)‐ylidene)propan‐2‐ones via Acid‐Catalyzed,Stereoselective 5‐Exo‐Dig Cyclization

A number of 3‐(4,4,5,5‐tetraethoxy‐1‐hydroxy‐1‐arylpent‐2‐ynyl)quinoxalin‐2(1H)‐ones, obtained by reacting the lithium acetylide of 3,3,4,4‐tetraethoxybut‐1‐yne (TEB) with 3‐aroylquinoxalin‐2(1H)‐ones, appeared to undergo stereoselective cyclization in the 5‐exo‐Dig manner when heated at reflux in acidic, aqueous THF. In each case, the products were the corresponding (E)‐1,1‐diethoxy‐3‐(3‐hydroxy‐3‐arylfuro[2,3‐b]quinoxalin‐2(3H)‐ylidene)propan‐2‐ones and 1,1‐diethoxy‐3‐hydroxy‐3‐(3‐arylfuro[2,3‐b]quinoxalin‐2‐yl)propan‐2‐one, which were isolated in an approximate ratio of 2:1 in high total yield. Irrespective of the structure of the aryl group, both compounds were stable solids when kept in a refridgerator (3 °C), but when the latter product was dissolved in chloroform and stored at room temperature, it rearranged smoothly and quantitatively to the former compound within a few days.     

Gluino production in electron-positron annihilation

We discuss the pair production of gluinos in electron-positron annihilation at LEP, in a model with soft supersymmetry breaking, allowing for mixing between the squarks. In much of the parameter space of the Minimal Supersymmetric Model (MSSM) the cross section corresponds to aZ branching ratio above 10^–5, even up to 10^–4. A non-observation of gluinos at this level restricts the allowed MSSM parameter space. In particular, it leads to lower bounds on the soft mass parameters in the squark sector.     

Synthesis and some chemical properties of 3,3,4,4-tetraethoxybut-1-yne

Ring opening of 1,1-dibromo-2-chloro-2-diethoxymethylcyclopropane in a mixture of ethanol and dichloromethane with 50% aqueous sodium hydroxide in the presence of triethylbenzylammonium chloride (TEBA) gave 3,3,4,4-tetraethoxybut-1-yne (TEB) in excellent yield. This alkyne appears to be thermally stable at least up to 150 °C. The compound is also stable in neutral and basic aqueous solutions. In acidic aqueous media, however, TEB is unstable and was converted to one or several products depending on the reaction conditions. The most useful reaction appears to be deketalization to give 1,1-diethoxybut-3-yn-2-one, which was obtained in quantitative yield under the optimum conditions.     

Monte Carlo exact goodness‐of‐fit tests for nonhomogeneous Poisson processes

Nonhomogeneous Poisson processes (NHPPs) are often used to model failure data from repairable systems, and there is thus a need to check model fit for such models. We study the problem of obtaining exact goodness‐of‐fit tests for parametric NHPPs. The idea is to use conditional tests given a sufficient statistic under the null hypothesis model. The tests are performed by simulating conditional samples given the sufficient statistic. Algorithms are presented for testing goodness‐of‐fit for the power law and the log‐linear law NHPP models. It is noted that while exact algorithms for the power law case are well known in the literature, the availability of such algorithms for the log‐linear case seems to be less known. A data example, as well as simulations, are considered. Copyright © 2010 John Wiley & Sons, Ltd.     

Exercising flexible load contracts: Two simple strategies

A flexible load contract is a type of swing option where the holder has the right to receive a given quantity of electricity within a specified period, at a fixed maximum effect (delivery rate). The contract is flexible, in the sense that delivery (the take hours) is called one day in advance. We investigate two simple strategies for exercising flexible load contracts, where both use price information from the forward market. For 10 contracts traded in the period 1997–2001, we calculate the performance of the two strategies and compare with the reported performance of one complex dynamic programming approach as well as the actual results obtained by three anonymous market participants. The comparison indicates that our simple computer‐efficient strategies perform better on average and produce more stable results. Copyright © 2007 John Wiley & Sons, Ltd.     

Addressing the Glycine‐Rich Loop of Protein Kinases by a Multi‐Facetted Interaction Network: Inhibition of PKA and a PKB Mimic

Protein kinases continue to be hot targets in drug discovery research, as they are involved in many essential cellular processes and their deregulation can lead to a variety of diseases. A series of 32 enantiomerically pure inhibitors was synthesized and tested towards protein kinase A (PKA) and protein kinase B mimic PKAB3 (PKA triple mutant). The ligands bind to the hinge region, ribose pocket, and glycine‐rich loop at the ATP site. Biological assays showed high potency against PKA, with K_i values in the low nanomolar range. The investigation demonstrates the significance of targeting the often neglected glycine‐rich loop for gaining high binding potency. X‐ray co‐crystal structures revealed a multi‐facetted network of ligand–loop interactions for the tightest binders, involving orthogonal dipolar contacts, sulfur and other dispersive contacts, amide–π stacking, and H‐bonding to organofluorine, besides efficient water replacement. The network was analyzed in a computational approach.