Coexisting Cardiac and Hematologic Disorders.

Patients with concomitant cardiac and hematologic disorders presenting for noncardiac surgery are challenging. Anemic patients with cardiac disease should be approached in a methodical fashion. Transfusion triggers and target should be based on underlying symptomatology. The approach to anticoagulation management in patients with artificial heart valves, cardiac devices, or severe heart failure in the operative setting must encompass a complete understanding of the rationale of a patient\u27s therapy as well as calculate the risk of changing this regimen. This article focuses common disorders and discusses strategies to optimize care in patients with coexisting cardiac and hematologic disease

On the Plutinos and Twotinos of the Kuiper Belt

We illuminate dynamical properties of Kuiper Belt Objects (KBOs) in the 3:2 (``Plutino'') and 2:1 (``Twotino'') Neptunian resonances within the model of resonant capture and migration. We analyze a series of numerical integrations, each involving the 4 migratory giant planets and 400 test particles distributed throughout trans-Neptunian space, to measure efficiencies of capture as functions of migration speed. Snapshots of the spatial distribution of resonant KBOs reveal that Twotinos cluster +/- 75 degrees away from Neptune's longitude, while Plutinos cluster +/- 90 degrees away. Longitudinal clustering persists even for surveys that are not volume-limited in their ability to detect resonant KBOs. Remarkably, between -90 degrees and -60 degrees of Neptune's longitude, we find the sky density of Twotinos to nearly equal that of Plutinos, despite the greater average distance of Twotinos. We couple our findings to observations to crudely estimate that the intrinsic Twotino population is within a factor of 3 of the Plutino population. Most strikingly, the migration model predicts that more Twotinos may lie at longitudes behind that of Neptune than ahead of it. The magnitude of the asymmetry amplifies dramatically with faster rates of migration and can be as large as 300%. A differential measurement of the sky density of 2:1 resonant objects behind of and in front of Neptune's longitude would powerfully constrain the migration history of that planet.Comment: AJ, in press, to appear in December 2002 issue. For version with higher resolution figures, see http://astron.berkeley.edu/~echiang/ppp/ppp.htm

(Never) Mind your p's and q's: Von Neumann versus Jordan on the Foundations of Quantum Theory

In two papers entitled "On a new foundation [Neue Begr\"undung] of quantum mechanics," Pascual Jordan (1927b,g) presented his version of what came to be known as the Dirac-Jordan statistical transformation theory. As an alternative that avoids the mathematical difficulties facing the approach of Jordan and Paul A. M. Dirac (1927), John von Neumann (1927a) developed the modern Hilbert space formalism of quantum mechanics. In this paper, we focus on Jordan and von Neumann. Central to the formalisms of both are expressions for conditional probabilities of finding some value for one quantity given the value of another. Beyond that Jordan and von Neumann had very different views about the appropriate formulation of problems in quantum mechanics. For Jordan, unable to let go of the analogy to classical mechanics, the solution of such problems required the identication of sets of canonically conjugate variables, i.e., p's and q's. For von Neumann, not constrained by the analogy to classical mechanics, it required only the identication of a maximal set of commuting operators with simultaneous eigenstates. He had no need for p's and q's. Jordan and von Neumann also stated the characteristic new rules for probabilities in quantum mechanics somewhat differently. Jordan (1927b) was the first to state those rules in full generality. Von Neumann (1927a) rephrased them and, in a subsequent paper (von Neumann, 1927b), sought to derive them from more basic considerations. In this paper we reconstruct the central arguments of these 1927 papers by Jordan and von Neumann and of a paper on Jordan's approach by Hilbert, von Neumann, and Nordheim (1928). We highlight those elements in these papers that bring out the gradual loosening of the ties between the new quantum formalism and classical mechanics.Comment: New version. The main difference with the old version is that the introduction has been rewritten. Sec. 1 (pp. 2-12) in the old version has been replaced by Secs. 1.1-1.4 (pp. 2-31) in the new version. The paper has been accepted for publication in European Physical Journal

Combinatorial synthesis and high-throughput photopotential and photocurrent screening of mixed-metal oxides for photoelectrochemical water splitting

A high-throughput method has been developed using a commercial piezoelectric inkjet printer for synthesis and characterization of mixed-metal oxide photoelectrode materials for water splitting. The printer was used to deposit metal nitrate solutions onto a conductive glass substrate. The deposited metal nitrate solutions were then pyrolyzed to yield mixed-metal oxides that contained up to eight distinct metals. The stoichiometry of the metal oxides was controlled quantitatively, allowing for the creation of vast libraries of novel materials. Automated methods were developed to measure the open-circuit potentials (Eoc), short-circuit photocurrent densities (Jsc), and current density vs. applied potential (J–E) behavior under visible light irradiation. The high-throughput measurement of Eoc is particularly significant because open-circuit potential measurements allow the interfacial energetics to be probed regardless of whether the band edges of the materials of concern are above, close to, or below the values needed to sustain water electrolysis under standard conditions. The Eoc measurements allow high-throughput compilation of a suite of data that can be associated with the composition of the various materials in the library, to thereby aid in the development of additional screens and to form a basis for development of theoretical guidance in the prediction of additional potentially promising photoelectrode compositions

Revisiting two-step Forbush decreases

Interplanetary coronal mass ejections (ICMEs) and their shocks can sweep out galactic cosmic rays (GCRs), thus creating Forbush decreases (FDs). The traditional model of FDs predicts that an ICME and its shock decrease the GCR intensity in a two-step profile. This model, however, has been the focus of little testing. Thus, our goal is to discover whether a passing ICME and its shock inevitably lead to a two-step FD, as predicted by the model. We use cosmic ray data from 14 neutron monitors and, when possible, high time resolution GCR data from the spacecraft International Gamma Ray Astrophysical Laboratory (INTEGRAL). We analyze 233 ICMEs that should have created two-step FDs. Of these, only 80 created FDs, and only 13 created two-step FDs. FDs are thus less common than predicted by the model. The majority of events indicates that profiles of FDs are more complicated, particularly within the ICME sheath, than predicted by the model. We conclude that the traditional model of FDs as having one or two steps should be discarded. We also conclude that generally ignored small-scale interplanetary magnetic field structure can contribute to the observed variety of FD profiles

One qubit almost completely reveals the dynamics of two

From the time dependence of states of one of them, the dynamics of two interacting qubits is determined to be one of two possibilities that differ only by a change of signs of parameters in the Hamiltonian. The only exception is a simple particular case where several parameters in the Hamiltonian are zero and one of the remaining nonzero parameters has no effect on the time dependence of states of the one qubit. The mean values that describe the initial state of the other qubit and of the correlations between the two qubits also are generally determined to within a change of signs by the time dependence of states of the one qubit, but with many more exceptions. An example demonstrates all the results. Feedback in the equations of motion that allows time dependence in a subsystem to determine the dynamics of the larger system can occur in both classical and quantum mechanics. The role of quantum mechanics here is just to identify qubits as the simplest objects to consider and specify the form that equations of motion for two interacting qubits can take.Comment: 6 pages with new and updated materia

Fast quantum algorithm for numerical gradient estimation

Given a blackbox for f, a smooth real scalar function of d real variables, one wants to estimate the gradient of f at a given point with n bits of precision. On a classical computer this requires a minimum of d+1 blackbox queries, whereas on a quantum computer it requires only one query regardless of d. The number of bits of precision to which f must be evaluated matches the classical requirement in the limit of large n.Comment: additional references and minor clarifications and corrections to version

Time Domain Mapping of Spin Torque Oscillator Effective Energy

Stochastic dynamics of spin torque oscillators (STOs) can be described in terms of magnetization drift and diffusion over a current-dependent effective energy surface given by the Fokker-Planck equation. Here we present a method that directly probes this effective energy surface via time-resolved measurements of the microwave voltage generated by a STO. We show that the effective energy approach provides a simple recipe for predicting spectral line widths and line shapes near the generation threshold. Our time domain technique also accurately measures the field-like component of spin torque in a wide range of the voltage bias values.Comment: 5 pages, 3 figures. Supplement included: 7 pages, 6 figure

Lorentz transformations that entangle spins and entangle momenta

Simple examples are presented of Lorentz transformations that entangle the spins and momenta of two particles with positive mass and spin 1/2. They apply to indistinguishable particles, produce maximal entanglement from finite Lorentz transformations of states for finite momenta, and describe entanglement of spins produced together with entanglement of momenta. From the entanglements considered, no sum of entanglements is found to be unchanged.Comment: 5 Pages, 2 Figures, One new paragraph and reference adde