Absence of an isotope effect in the magnetic resonance in high-TcT_c superconductors

An inelastic neutron scattering experiment has been performed in the high-temperature superconductor $\rm YBa_2Cu_3O_{6.89}$ to search for an oxygen-isotope shift of the well-known magnetic resonance mode at 41 meV. Contrary to a recent prediction (I. Eremin, {\it et al.}, Phys. Rev. B {\bf 69}, 094517 (2004)), a negligible shift (at best $\leq$ +0.2 meV) of the resonance energy is observed upon oxygen isotope substitution ($^{16}$O$\to^{18}$O). This suggests a negligible spin-phonon interaction in the high-$T_c$ cuprates at optimal doping.Comment: 3 figure

The Development and Application of a Process-oriented Thermometer of IT Business Value

The issue of whether firms are receiving an adequate return on their investment in information technology (IT) continues to pervade managerial decision making. While productivity and other financial metrics are established hallmarks of IT investment evaluation, research has called for broader and richer metrics that can take into account the diversity of IT impacts. In this paper, we extend previous instrument development research to develop and test a process-oriented thermometer of IT business value using survey data based on executives\u27 perceptions of IT impacts at multiple points along the value chain. Consistent with earlier research, we find that our process measures are sensitive to differences in industry, firm size, and business strategy. Through additional analysis of post-implementation reviews of IT impacts in four firms, we find consistency of within-firm perceptual measures among teams of senior executives, highlighting the potential for our thermometer to gauge the level of IT impacts within a single firm. We conclude that process-oriented perceptual measures can offer new and useful insights into IT impacts, complementing what we already know from firm-level objective metrics

On the Dichotomy between the Nodal and Antinodal Excitations in High-temperature Superconductors

Angle-resolved photoemission data on optimally- and under-doped high temperature superconductors reveal a dichotomy between the nodal and antinodal electronic excitations. In this paper we propose an explanation of this unusual phenomenon by employing the coupling between the quasiparticle and the commensurate/incommensurate magnetic excitations.Comment: 11 pages, 9 figure

Measurement of Newtonian fluid slip using a torsional ultrasonic oscillator

The composite torsional ultrasonic oscillator, a versatile experimental system, can be used to investigate slip of Newtonian fluid at a smooth surface. A rigorous analysis of slip-dependent damping for the oscillator is presented. Initially, the phenomenon of finite surface slip and the slip length are considered for a half-space of Newtonian fluid in contact with a smooth, oscillating solid surface. Definitions are revisited and clarified in light of inconsistencies in the literature. We point out that, in general oscillating flows, Navier's slip length b is a complex number. An intuitive velocity discontinuity parameter of unrestricted phase is used to describe the effect of slip on measurement of viscous shear damping. The analysis is applied to the composite oscillator and preliminary experimental work for a 40 kHz oscillator is presented. The Non-Slip Boundary Condition (NSBC) has been verified for a hydrophobic surface in water to within ~60 nm of |b|=0 nm. Experiments were carried out at shear rate amplitudes between 230 and 6800 /s, corresponding to linear displacement amplitudes between 3.2 and 96 nm.Comment: Revised with minor edits for revie

Observation of Magnetic Moments in the Superconducting State of YBa2_2Cu3_3O6.6_{6.6}

Neutron Scattering measurements for YBa$_2$Cu$_3$O$_{6.6}$ have identified small magnetic moments that increase in strength as the temperature is reduced below $T^\ast$ and further increase below $T_c$. An analysis of the data shows the moments are antiferromagnetic between the Cu-O planes with a correlation length of longer than 195 \AA in the $a$-$b$ plane and about 35 \AA along the c-axis. The origin of the moments is unknown, and their properties are discusssed both in terms of Cu spin magnetism and orbital bond currents.Comment: 9 pages, and 4 figure

Information Technology and the Search for Organizational Agility: A Systematic Review with Future Research Possibilities

Organizations are increasingly turning to information technology (IT) to help them respond to unanticipated environmental threats and opportunities. In this paper, we introduce a systematic review of the literature on IT-enabled agility, helping to establish the boundary between what we know and what we don’t know. We base our review on a wide body of literature drawn from the AIS Basket of Eight IT journals, a cross-section of non-Basket journals, IT practitioner outlets, and premier international IS conferences. We review the use of different theoretical lenses used to investigate the relationship between IT and organizational agility and how the literature has conceptualized agility, its antecedents, and consequences. We also map the evolution of the literature through a series of stages that highlight how researchers have built on previous work. Lastly, we discuss opportunities for future research in an effort to close important gaps in our understanding