608 research outputs found
Symposium on State and Local Taxation
The commerce clause as an instrument of federalism facilitates a system of government that places a national government over fifty sovereign states. Federalism requires a balancing of the interest in a unified national approach to government with the competing interest in state sovereignty. As Justice Brennan explained:
Our Constitution is an instrument of federalism. The Constitution furnishes the structure for the operation of the States with respect to the National Government and with respect to each other.. ..Because there are 49 States and much of the Nation\u27s commercial activity is carried on by enterprises having contacts with more States than one, a common and continuing problem of constitutional interpretation has been that of adjusting the demands of individual States to regulate and tax these enterprises in light of the multi-state nature of our federation.
The commerce clause provides: The Congress shall have Power ... To regulate Commerce with foreign Nations, and among the several States, and with the Indian Tribes. \u27 The commerce clause has been interpreted not only as conferring power on the national government to regulate commerce, but also as limiting the states\u27 power to interfere with commerce. This restriction on state power often is referred to as the negative implication of the commerce clause or as the dormant commerce clause principle. Under the authority of the commerce clause, the United States Supreme Court has struck down as unconstitutional a variety of state regulatory and taxation measures as unduly burdening commerce
Interactions between vaccinia virus and sensitized macrophages in vitro
The action of peritoneal exudate cells (PEC) from normal and vaccinia virus infected mice on infectious vaccinia virus particles was investigatedin vitro. PEC from immune mice showed a significantly higher infectivity titre reduction (virus clearance, VC) than normal cells. This effect could be clearly attributed to the macrophage. Vaccinia virus multiplied in PEC from normal animals while there was no virus propagation in cells from immunized mice. The release of adsorbed or engulfed virus was reduced significantly in PEC from immunized animals. Anti-vaccinia-antibodies seem to activate normal macrophages to increased virus clearance. This stimulating effect was demonstrable only in the IgG fraction of the antiserum.
The activity of macrophages from mice injected three times over a period of 14 days with vaccinia virus could be entirely blocked with anti-mouse-IgG, while PEC from mice injected one time six days previously were not inhibited
Decoherence in qubits due to low-frequency noise
The efficiency of the future devices for quantum information processing is
limited mostly by the finite decoherence rates of the qubits. Recently a
substantial progress was achieved in enhancing the time, which a solid-state
qubit demonstrates a coherent dynamics. This progress is based mostly on a
successful isolation of the qubits from external decoherence sources. Under
these conditions the material-inherent sources of noise start to play a crucial
role. In most cases the noise that quantum device demonstrate has 1/f spectrum.
This suggests that the environment that destroys the phase coherence of the
qubit can be thought of as a system of two-state fluctuators, which experience
random hops between their states. In this short review we discuss the current
state of the theory of the decoherence due to the qubit interaction with the
fluctuators. We describe the effect of such an environment on different
protocols of the qubit manipulations - free induction and echo signal. It turns
out that in many important cases the noise produced by the fluctuators is
non-Gaussian. Consequently the results of the interaction of the qubit with the
fluctuators are not determined by the pair correlation function only.
We describe the effect of the fluctuators using so-called spin-fluctuator
model. Being quite realistic this model allows one to evaluate the qubit
dynamics in the presence of one fluctuator exactly. This solution is found, and
its features, including non-Gaussian effects are analyzed in details. We extend
this consideration for the systems of large number of fluctuators, which
interact with the qubit and lead to the 1/f noise. We discuss existing
experiments on the Josephson qubit manipulation and try to identify
non-Gaussian behavior.Comment: 25 pages, 7 figure
Review of Student-Built Spectroscopy Instrumentation Projects
Copyright © 2020 American Chemical Society and Division of Chemical Education, Inc. One challenge of teaching chemical analysis is the proliferation of sophisticated, but often impenetrable, instrumentation in the modern laboratory. Complex instruments, and the software that runs them, distance students from the physical and chemical processes that generate the analytical signal. A solution to this challenge is the introduction of a student-driven instrument-building project. Visible absorbance spectroscopy is well-suited to such a project due to its relative simplicity and the ubiquity of absorbance measurements. This Article reviews simple instructor- A nd student-built instruments for spectroscopy, providing an overview of common designs, components, and applications. This comprehensive summary includes options that are suitable for in-person or remote learning with K-12 students and undergraduates in general chemistry, analytical chemistry, instrumental analysis, and electronics courses
Introduction: looking beyond the walls
In its consideration of the remarkable extent and variety of non-university researchers, this book takes a broader view of âknowledgeâ and âresearchâ than in the many hot debates about todayâs knowledge society, âlearning ageâ, or organisation of research. It goes beyond the commonly held image of âknowledgeâ as something produced and owned by the full-time experts to take a look at those engaged in active knowledge building outside the university walls
Theory of the ground state spin of the NV- center in diamond: I. Fine structure, hyperfine structure, and interactions with electric, magnetic and strain fields
The ground state spin of the negatively charged nitrogen-vacancy center in
diamond has been the platform for the recent rapid expansion of new frontiers
in quantum metrology and solid state quantum information processing. In ambient
conditions, the spin has been demonstrated to be a high precision magnetic and
electric field sensor as well as a solid state qubit capable of coupling with
nearby nuclear and electronic spins. However, in spite of its many outstanding
demonstrations, the theory of the spin has not yet been fully developed and
there does not currently exist thorough explanations for many of its
properties, such as the anisotropy of the electron g-factor and the existence
of Stark effects and strain splittings. In this work, the theory of the ground
state spin is fully developed for the first time using the molecular orbital
theory of the center in order to provide detailed explanations for the spin's
fine and hyperfine structures and its interactions with electric, magnetic and
strain fields.Comment: 12 pages, 3 figures, 3 table
The solar eclipse and associated atmospheric variations observed in South Korea on 22 July 2009
A partial solar eclipse occurred in South Korea on 22 July 2009. It started at 09:30 a.m. and lasted until 12:14 LST with coverage of between 76.8% and 93.1% of the sun. The observed atmospheric effects of the eclipse are presented. It was found that from the onset of the eclipse, solar radiation was reduced by as much as 88.1ââŒâ89.9% at the present research centre. Also, during the eclipse, air temperature decreased slightly or remained almost unchanged. After the eclipse, however, it rose by 2.5 to 4.5°C at observed stations. Meanwhile, relative humidity increased and wind speeds were lowered by the eclipse. Ground-level ozone was observed to decrease during the event
Electron spin as a spectrometer of nuclear spin noise and other fluctuations
This chapter describes the relationship between low frequency noise and
coherence decay of localized spins in semiconductors. Section 2 establishes a
direct relationship between an arbitrary noise spectral function and spin
coherence as measured by a number of pulse spin resonance sequences. Section 3
describes the electron-nuclear spin Hamiltonian, including isotropic and
anisotropic hyperfine interactions, inter-nuclear dipolar interactions, and the
effective Hamiltonian for nuclear-nuclear coupling mediated by the electron
spin hyperfine interaction. Section 4 describes a microscopic calculation of
the nuclear spin noise spectrum arising due to nuclear spin dipolar flip-flops
with quasiparticle broadening included. Section 5 compares our explicit
numerical results to electron spin echo decay experiments for phosphorus doped
silicon in natural and nuclear spin enriched samples.Comment: Book chapter in "Electron spin resonance and related phenomena in low
dimensional structures", edited by Marco Fanciulli. To be published by
Springer-Verlag in the TAP series. 35 pages, 9 figure
Webâbased Weight Management Programs in an Integrated Health Care Setting: A Randomized, Controlled Trial
Objective : To assess the efficacy of a Webâbased tailored behavioral weight management program compared with Webâbased informationâonly weight management materials. Research Methods and Procedures : Participants, 2862 eligible overweight and obese (BMI = 27 to 40 kg/m 2 ) members from four regions of Kaiser Permanente's integrated health care delivery system, were randomized to receive either a tailored expert system or informationâonly Webâbased weight management materials. Weight change and program satisfaction were assessed by selfâreport through an Internetâbased survey at 3â and 6âmonth followâup periods. Results : Significantly greater weight loss at followâup was found among participants assigned to the tailored expert system than among those assigned to the informationâonly condition. Subjects in the tailored expert system lost a mean of 3 ± 0.3% of their baseline weight, whereas subjects in the informationâonly condition lost a mean of 1.2 ± 0.4% ( p < 0.0004). Participants were also more likely to report that the tailored expert system was personally relevant, helpful, and easy to understand. Notably, 36% of enrollees were AfricanâAmerican, with enrollment rates higher than the general proportion of African Americans in any of the study regions. Discussion : The results of this large, randomized control trial show the potential benefit of the Webâbased tailored expert system for weight management compared with a Webâbased informationâonly weight management program.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/93691/1/oby.2006.34.pd
- âŠ