18,823 research outputs found
Superconducting Surface Impedance under Radiofrequency Field
Based on BCS theory with moving Cooper pairs, the electron states
distribution at 0K and the probability of electron occupation with finite
temperature have been derived and applied to anomalous skin effect theory to
obtain the surface impedance of a superconductor under radiofrequency (RF)
field. We present the numerical results for Nb and compare these with
representative RF field-dependent effective surface resistance measurements
from a 1.5 GHz resonant structure
The collective gyration of a heavy ion cloud in a magnetized plasma
In both the ionospheric barium injection experiments CRIT 1 and CRIT 2, a long duration oscillation was seen with a frequency close to the gyro frequency of barium and a time duration of about one second. A model for the phenomena which was proposed for the CRIT 1 experiment is compared to the results from CRIT 2 which made a much more complete set of measurements. The model follows the motion of a low Beta ion cloud through a larger ambient plasma. The internal field of the model is close to antiparallel to the injection direction v sub i but slightly tilted towards the self polarization direction E sub p = -V sub i by B. As the ions move across the magnetic field, the space charge is continuously neutralized by magnetic field aligned electron currents from the ambient ionosphere, drawn by the divergence in the perpendicular electric field. These currents give a perturbation of the magnetic field related to the electric field perturbation by Delta E/Delta B approximately equal to V sub A. The model predictions agree quite well with the observed vector directions, field strengths, and decay times of the electric and magnetic fields in CRIT 2. The possibility to extend the model to the active region, where the ions are produces in this type of self-ionizing injection experiments, is discussed
An evaluation of exercises for the development of word recognition and word meaning in grade five
Thesis (Ed.M.)--Boston Universit
Implementing Quantum Gates by Optimal Control with Doubly Exponential Convergence
We introduce a novel algorithm for the task of coherently controlling a
quantum mechanical system to implement any chosen unitary dynamics. It performs
faster than existing state of the art methods by one to three orders of
magnitude (depending on which one we compare to), particularly for quantum
information processing purposes. This substantially enhances the ability to
both study the control capabilities of physical systems within their coherence
times, and constrain solutions for control tasks to lie within experimentally
feasible regions. Natural extensions of the algorithm are also discussed.Comment: 4+2 figures; to appear in PR
Chapter Three. EED library as a basis for systematic reviews
3.1 Defining Systematic Review Question Priorities
3.2 Determining Relevance to the Systematic Review
3.3 Acquisition of References and Copyright Fair Use Compliance
3.4 Documenting Relevance to the Systematic Review
3.5 Data Extraction for the Systematic Review
3.6 EED Library: Search Results Overview
3.7 Quality Control
3.8 EED Library Statushttps://digitalcommons.wustl.edu/tropicalenteropathybook/1004/thumbnail.jp
Chapter Five. Systematic review results by biomarker classifications
5.1 Markers of Absorption and Permeability Overview
5.2 Markers of Absorption
5.3 Markers of Permeability
5.4 Markers of Digestion
5.5 Markers of Intestinal Inflammation and Intestinal Immune Activation
5.6 Markers of Systemic Inflammation and Systemic Immune Activation
5.7 Markers of Microbial Drivers
5.8 Markers of Nonspecific Intestinal Injury
5.9 Markers of Extra-Small Intestinal Function
5.10 Relationships Between Markers of EED, Including Histopathology
5.11 Relationships between EED Biomarkers and Growth or Other Outcomes of Interesthttps://digitalcommons.wustl.edu/tropicalenteropathybook/1006/thumbnail.jp
Chapter Six. Conclusions and future implications
6.1 Summary of Findings
6.2 Future Biomarker and Diagnostics Researchhttps://digitalcommons.wustl.edu/tropicalenteropathybook/1007/thumbnail.jp
Eddy turbulence, the double mesopause, and the double layer of atomic oxygen
In this study, we consider the impact of eddy turbulence on temperature and
atomic oxygen distribution when the peak of the temperature occurs in the
upper mesosphere. A previous paper (Vlasov and Kelley, 2010) considered the
simultaneous impact of eddy turbulence on temperature and atomic oxygen
density and showed that eddy turbulence provides an effective mechanism to
explain the cold summer and warm winter mesopause observed at high
latitudes. Also, the prevalent role of eddy turbulence in this case removes
the strong contradiction between seasonal variations of the O density
distribution and the impact of upward/downward motion corresponding to
adiabatic cooling/heating of oxygen atoms. Classically, there is a single
minimum in the temperature profile marking the location of the mesopause.
But often, a local maximum in the temperature is observed in the height
range of 85–100 km, creating the appearance of a double mesopause (Bills
and Gardner, 1993; Yu and She, 1995; Gusev et al., 2006). Our results show
that the relative temperature maximum in the upper mesosphere (and thus the
double mesopause) can result from heating by eddy turbulence. According to
our model, there is a close connection between the extra temperature peak in
the mesosphere and the oxygen atom density distribution. The main feature of
the O density height profile produced by eddy turbulence in our model is a
double peak instead of a single peak of O density. A rocket experiment
called TOMEX confirms these results (Hecht et al., 2004). Applying our model
to the results of the TOMEX rocket campaign gives good agreement with both
the temperature and oxygen profiles observed. Climatology of the midlatitude
mesopause and green line emission shows that the double mesopause and the
double layers of the green line emission, corresponding to the double O
density height profile, are mainly observed in spring and fall (Yu and She,
1995; Liu and Shepherd, 2006). Further observations of the oxygen atom
densities and the double mesopause would improve our understanding of the
impact of turbulence on critical mesospheric parameters
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An Experimental and Modeling Study of Nanoparticle Formation and Growth from Dimethylamine and Nitric Acid
Observation of centimetre-scale argon diffusion in alkali feldspars: implications for <sup>40</sup>Ar/<sup>39</sup>Ar thermochronology
New data from a gem-quality feldspar from Itrongay, Madagascar, record naturally occurring 40Ar/39Ar age profiles which can be numerically modelled by invoking a single diffusion mechanism and show that microtexturally simple crystals are capable of recording complex thermal histories. We present the longest directly measured, naturally produced 40Ar*-closure profiles from a single, homogeneous orthoclase feldspar. These data appear to confirm the assumption that laboratory derived diffusion parameters are valid in nature and over geological timescales. Diffusion domains are defined by crystal faces and ancient cracks, thus in gem-quality feldspars the diffusion domain size equates to the physical grain size. The data also illustrate the potential of large, gem-quality feldspars to record detailed thermal histories over tens of millions of years and such samples should be considered for future studies on the slow cooling of continental crust
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