Pentaquark Searches at CDF

Recently there has been revival of interest in exotic baryon spectroscopy triggered by experimental evidence for pentaquarks containing u,d,s and c-quarks. We report results of the searches for pentaquark states in decays to p K0S, Xi- pi+,- and D*- p performed at CDF detector using 220 pb-1 sample of pp= interactions at sqrt(s) of 1.96 TeV. No evidence for narrow resonances were found in either mode.Comment: Presented at 6th International Conference on Hyperons, Charm and Beauty Hadrons (BEACH 2004), Chicago, Illinois, 27 Jun - 3 Jul 200

Analyzing competitiveness of automotive industry through cumulative belief degrees

Copyright @ 2012 The European Mathematical SocietyThis study aims to analyze the automotive industry from competitiveness perspective using a novel cumulative belief degrees (CBD) approach. For this purpose, a mathematical model based on CBD is proposed to quantify the relations among the variables in a system. This model is used to analyze the Turkish Automotive Industry through scenario analysis.This research is supported by SEDEFED (Federation of Industrial Associations), REF (TÜSİAD Sabanci University Competitiveness Forum), and OSD (Automotive Manufacturers Association

Continuously tunable terahertz metamaterial employing magnetically actuated cantilevers

Cataloged from PDF version of article.Terahertz metamaterial structures that employ flexing microelectromechanical cantilevers for tuning the resonance frequency of an electric split-ring resonator are presented. The tuning cantilevers are coated with a magnetic thin-film and are actuated by an external magnetic field. The use of cantilevers enables continuous tuning of the resonance frequency over a large frequency range. The use of an externally applied magnetic field for actuation simplifies the metamaterial structure and its use for sensor or filter applications. A structure for minimizing the actuating field is derived. The dependence of the tunable bandwidth on frequency is discussed. (c) 2011 Optical Society of Americ

Elastic softening of leucite and the lack of polar domain boundaries

Elastic properties of leucite have been investigated using resonant ultrasound spectroscopy over a temperature range from 300 K to 1400 K. According to these measurements, elastic moduli soften by ~50% at the Ia3d-I41/acd ferroelastic transition temperature Tc1 = 940 K relative to the value at 1400 K. A second softening is observed at Tc2 = 920 K, corresponding to the structural change from the space group I41/acd to I41/a. These elastic anomalies are analyzed in a simple model of a pseudoproper ferroelastic transition under the assumption that the transitions observed at Tc1 and Tc2 can be approximated by a single pseudoproper ferroelastic transition. The two phase transitions are accompanied by a single peak in mechanical damping attributed to the high mobility of twin walls in the intermediate phase followed by pinning in the low temperature phase. To determine whether twin walls in tetragonal leucite are polar, resonant piezoelectric spectroscopy and second harmonic generation measurements were performed but no evidence of polarity was found.E.K.H.S. is grateful to EPSRC (EP/K009702/1) and the Leverhulme Foundation (RPG-2012-564) for support. M.A.C. acknowledges NERC grants (NER/A/S/2000/01055 and NE/F017081/1).This is the final version of the article. It first appeared from De Gruyter via http://dx.doi.org/10.2138/am-2015-5313ccb

Noncoherent Space-Time Coding: An Algebraic Perspective

Cataloged from PDF version of article.The design of space–time signals for noncoherent block-fading channels where the channel state information is not known a priori at the transmitter and the receiver is considered. In particular, a new algebraic formulation for the diversity advantage design criterion is developed. The new criterion encompasses, as a special case, the well-known diversity advantage for unitary space–time signals and, more importantly, applies to arbitrary signaling schemes and arbitrary channel distributions. This criterion is used to establish the optimal diversity-versus-rate tradeoff for training based schemes in block-fading channels. Our results are then specialized to the class of affine space–time signals which allows for a low complexity decoder. Within this class, space–time constellations based on the threaded algebraic space–time (TAST) architecture are considered. These constellations achieve the optimal diversity-versus-rate tradeoff over noncoherent block-fading channels and outperform previously proposed codes in the considered scenarios as demonstrated by the numerical results. Using the analytical and numerical results developed in this paper, nonunitary space–time codes are argued to offer certain advantages in block-fading channels where the appropriate use of coherent space–time codes is shown to offer a very efficient solution to the noncoherent space–time communication paradigm

Transient surface photovoltage in n- and p-GaN as probed by x-ray photoelectron spectroscopy

Cataloged from PDF version of article.Transient surface photovoltage (SPV) of n and p-GaN was measured using x-ray photoelectron spectroscopy (XPS) with a time resolution of 0.1 s. The measured SPV transients for both n- and p-GaN are << 0.1 s, and for the n-GaN they are not affected by flood-gun electrons. However, for the p-GaN, the transient character of the SPV is dramatically changed in the presence of flood-gun electrons. The combination of time-resolved XPS, flood gun, and laser illumination give us a new way to study the surface electronic structure and other surface properties of semiconducting materials in a chemically specific fashion. (C) 2011 American Institute of Physics

Effect of pores and grain size on the elastic and piezoelectric properties of quartz-based materials

The role of grain size and porosity in the piezoelectric and elastic properties of SiO2-based materials was investigated using resonant piezoelectric spectroscopy, RPS, and resonant ultrasound spectroscopy, RUS. RPS performed on agate revealed a piezoelectric effect comparable in magnitude to that in single crystal quartz. The observed strong piezoelectricity in agate requires preferential orientation of SiO2 during crystal growth. Similarly, in novaculite and sandstone finite (but weak) RPS signals were evident, suggesting that the expected randomization of the piezoelectric quartz grains is incomplete. On the other hand, Vycor, a silica glass with a porosity of 40%, showed no evidence of the piezoelectric effect. According to temperature dependent RPS and RUS measurements, the α-β transition temperature in quartz does not change in polycrystalline samples. Finally, the temperature dependence under heating of the elastic constants is reversible in quartz and agate and irreversible in sandstone and vycor.RUS facilities in Cambridge were established through grant no. NE/B505738/1 to MAC from the Natural Environment Research Council. EKHS is grateful to the Leverhulme Foundation (RPG-2012-564) and EPSRC (EP/K009702/1) for financial support.This is the final version. It was first published by De Gruyter at http://www.degruyter.com/view/j/ammin.2015.100.issue-5-6/am-2015-5180ccby/am-2015-5180ccby.xm