Saturation in “nonmagnetic” stainless steel

Scientific equipment often uses “nonmagnetic” stainless steel, relying on the steel’s nonmagnetic behavior to leave external magnetic fields unaltered. However, stainless steel’s permeability can rise significantly when it is welded or machined, possibly perturbing an external field. Such perturbations will diminish well above the stainless steel’s saturation point. The authors measured the permeability of both welded and machined 304 stainless steel as a function of an external magnetic field, and found that both saturate at fields of approximately 0.25 T

Crisis in the American courts: Greylord and the destruction of fiduciary bonds between the justice system and society

Includes bibliographical references.While it is commonly accepted and agreed upon that judges ought not to be partial, which (for reasons which will be discussed later) in the case of the judge necessarily implies corrupt, very seldom is there a reason given as to why the judge ought not to be partial to one litigant or the other. Perhaps this is because the judiciary is considered, as it was by the Founding Fathers, to be the weakest branch of government and therefore the least able to do harm, or perhaps it is because the answer to this question is considered too obvious and therefore uninteresting. Nevertheless, with the ever-expanding role of the judicial system into the policy-making role that was traditionally reserved solely for the legislature (such as can be seen in recent cases involving affirmative action, busing, and abortion, just to name a few) it is time to re-examine the role of the judge in the judicial system and his position in, responsibility to, and relationship with the rest of society

Charge dynamics in the half-metallic ferromagnet CrO\u3csub\u3e2\u3c/sub\u3e

Infrared spectroscopy is used to investigate the electronic structure and charge carrier relaxation in crystalline films of CrO2 which is the simplest of all half-metallic ferromagnets. Chromium dioxide is a bad metal at room temperature but it has a remarkably low residual resistivity (\u3c5 \u3eμΩ cm) despite the small spectral weight associated with free carrier absorption. The infrared measurements show that low residual resistivity is due to the collapse of the scattering rate at ω\u3c2000 \u3ecm-1. The blocking of the relaxation channels at low v and T can be attributed to the unique electronic structure of a half-metallic ferromagnet. In contrast to other ferromagnetic oxides, the intraband spectral weight is constant below the Curie temperature

Classical versus Quantum Time Evolution of Densities at Limited Phase-Space Resolution

We study the interrelations between the classical (Frobenius-Perron) and the quantum (Husimi) propagator for phase-space (quasi-)probability densities in a Hamiltonian system displaying a mix of regular and chaotic behavior. We focus on common resonances of these operators which we determine by blurring phase-space resolution. We demonstrate that classical and quantum time evolution look alike if observed with a resolution much coarser than a Planck cell and explain how this similarity arises for the propagators as well as their spectra. The indistinguishability of blurred quantum and classical evolution implies that classical resonances can conveniently be determined from quantum mechanics and in turn become effective for decay rates of quantum correlations.Comment: 10 pages, 3 figure

Nondiffusive spin dynamics in a two-dimensional electron gas

We describe measurements of spin dynamics in the two-dimensional electron gas in GaAs=GaAlAs quantum wells. Optical techniques, including transient spin-grating spectroscopy, are used to probe the relaxation rates of spin polarization waves in the wave vector range from zero to 6 x 104 cm-1. We find that the spin polarization lifetime is maximal at a nonzero wave vector, in contrast with expectations based on ordinary spin diffusion, but in quantitative agreement with recent theories that treat diffusion in the presence of spin-orbit couplin

Rapid diffusion of electrons in GaMnAs

We report ultrafast transient-grating measurements, above and below the Curie temperature, of the dilute ferromagnetic semiconductor (Ga,Mn)As containing 6% Mn. At 80 K (15 K), we observe that photoexcited electrons in the conduction band have a lifetime of 8 ps (5 ps) and diffuse at about 70 cm2/s (60 cm2/s). Such rapid diffusion requires either an electronic mobility exceeding 7,700 cm2/Vs or a conduction-band effective mass less than half the GaAs value. Our data suggest that neither the scattering rate nor the effective mass of the (Ga,Mn)As conduction band differs significantly from that of GaAs.Comment: 5 pages, 3 figures. Differs from the previous version in incorporating additional data and changes made during the review process. Differs from the published version in including section headings and in omitting AIP copy-edits. No substantial differences in scientific conclusions from either versio

Case Report: Oculomotor Palsy With Cyclic Spasms in a Patient With Charcot-Marie-Tooth Disease Type 1

Oculomotor palsy with cyclic spasms is an extremely rare condition whose exact pathophysiology remains a mystery. We followed a boy from the onset of symptoms at the age of ten months until 15 years and documented the case with video oculography. In addition, he was diagnosed with hereditary motor and sensory neuropathy (Charcot-Marie-Tooth disease type 1). Although a pure coincidence cannot be ruled out, it is conceivable that the underlying demyelinating neuropathy of this patient rendered the oculomotor nerve more susceptible to damage

The Worldwide Alzheimer\u27s Disease Neuroimaging Initiative: ADNI-3 updates and global perspectives

The Worldwide Alzheimer\u27s Disease Neuroimaging Initiative (WW-ADNI) is a collaborative effort to investigate imaging and biofluid markers that can inform Alzheimer\u27s disease treatment trials. It is a public-private partnership that spans North America, Argentina, Australia, Canada, China, Japan, Korea, Mexico, and Taiwan. In 2004, ADNI researchers began a naturalistic, longitudinal study that continues today around the globe. Through several successive phases (ADNI-1, ADNI-GO, ADNI-2, and ADNI-3), the study has fueled amyloid and tau phenotyping and refined neuroimaging methodologies. WW-ADNI researchers have successfully standardized analyses and openly share data without embargo, providing a rich data set for other investigators. On August 26, 2020, the Alzheimer\u27s Association convened WW-ADNI researchers who shared updates from ADNI-3 and their vision for ADNI-4