Simple Zeros of the Riemann Zeta-Function

Assuming the Riemann Hypothesis, Montgomery showed by meansof his pair correlation method that at least two-thirds of thezeros of Riemann's zeta-function are simple. Later he and Taylorimproved this to 67.25 percent and, more recently, Cheer andGoldston increased the percentage to 67.2753. Here we proveby a new method that if the Riemann and Generalized LindelöofHypotheses hold, then at least 70.3704 percent of the zerosare simple and at least 84.5679 percent are distinct. Our methoduses mean value estimates for various functions defined by Dirichletseries sampled at the zeros of the Riemann zeta-function. 1991Mathematics Subject Classification: 11M26.     

Quantum Zeno and anti-Zeno paradoxes

Continuous observation of a time independent projection operator is known to prevent change of state (the quantum Zeno paradox). We discuss the recent result that generic continuous measurement of time dependent projection operators will in fact ensure change of state: an anti-Zeno paradox.     

Developments in MALDI Mass Spectrometry: The Quest for the Perfect Matrix

Abstract

The topic of matrix-assisted laser desorption/ionization (MALDI) mass spectrometry has received much attention over the past several years and with the award of the Nobel Prize to Tanaka based on his landmark paper in 1988, has received even more recent attention. This review focuses on the search for an ideal matrix and generally covers the period from the mid 1990's to the present. There have been a number of excellent and comprehensive reviews on MALDI ion formation and a brief summary of some of the most important conclusions is given here. With respect to the applications of MALDI, the present review focuses primarily on polymer analysis, although in this area too, excellent reviews have been published that include consideration of the MALDI method. Although we make some mention of other uses of MALDI (e.g., to proteins and peptides) and other biological applications, we emphasize the polymer uses in the present review.     

粉粒体两相流的电容层析成象测量

粉粒体系统中的固相浓度分布的在线测量是十分困难的问题．电容层析成象技术是一种近年来发展起来的非侵入式快速浓度场测量技术．它不干扰流场，不受流动中颗粒浓度、加速度、不透明等因素的制约．本文讨论其测量原理、应用、近期进展、存在的主要问题及其解决的对策．     

ac Conductivity of mixed spinel NiAl0.7Cr0.7Fe0.6O4

ac Conductivity measurements are carried out across the metal to insulator transition in NiAl_0.7Cr_0.7Fe_0.6O₄. The low frequency data is analyzed using Summerfield scaling theory for hopping conductivity. The exponent of the scaling behavior has significantly different values in the conducting and insulating regimes. The hopping frequency and the zero frequency conductivity are found to increase with temperature, slowly in the metallic regime and rapidly in the insulating regime.     

A comprehensive and comparative analysis for MALDI FTMS lipid and phospholipid profiles from biological samples

Described here is a computationally automated method for translating complex accurate mass spectra into biologically relevant and meaningful data. Rapid profiling of detailed high resolution mass spectra resulting from direct analysis of whole cells and tissues by matrix-assisted laser desorption/ionization (MALDI) Fourier transform mass spectrometry (FTMS) is discussed. Lipid and phospholipid ions create complex spectra containing multiple m/z values corresponding to the same fundamental chemical species. A computational approach is employed to sort ions, with mass to charge ratios lower than m/z 1000, into groups of similar lipid and phospholipid compositions for comprehensive and rapid analysis. By sorting or binning ions in this manner, variations in the degree of cation exchange can be avoided, thus increasing the comparability of the data. The result is displayed as a histogram that is easily interpretable and comparable with similar analyses and is particularly useful for direct comparison of similar tissues. Spectra of leaves from a healthy Prunus persica (peach) tree are compared with those from leaves infected by the fungus Taphrina deformans. Although the infection can be seen as a difference in leaf structure and by visual inspection of the mass spectra, the method described here details the chemical difference in phospholipid compositions and their relative abundances.     

Local canted spin behaviour in Co1.4−x Zn x Ge0.4Fe1.2O4 spinels: A macroscopic, mesoscopic and microscopic study

DC magnetization, neutron depolarization and neutron diffraction (with both polarized and unpolarized neutrons) measurements have been reported for the Co_1.1−x Zn _x Ge_0.1Fe_1.2O₁ spinels with x=0.5, 0.6 and 0.7. Neutron depolarization and neutron diffraction measurements confirm the presence of a long range ferrimagnetic ordering of the local canted spins in these ferrite samples. The observed features of low field magnetization have been explained under the framework of thermally activated domain wall movement of ferrimagnetic arrangement of local canted spins. An important role of magnetic anisotropy (due to the presence of Co²⁺ ions) in establishing the magnetic ordering and domain kinetics in these ferrites has been observed.