3,735 research outputs found
Everett (Shep) Hurd\u27s account of the Brady Incident
This is the official deposition of Everett S. (Shep) Hurd, owner of Dakin\u27s Sporting Goods on Central Street in Bangor, of the events that took place between September 21 and October 12, 1937. These events culminated in the demise of the noted gangster Al Brady and Clarence Lee Shaffer, and the arrest and subsequent trial and execution of James Dalhover. It was taken in evidence by Special Agent W. J. Devereux of the FBI, on October 12, 1937.https://digicom.bpl.lib.me.us/spc_brady_bk/1000/thumbnail.jp
A comparison of methods for DPLL loop filter design
Four design methodologies for loop filters for a class of digital phase-locked loops (DPLLs) are presented. The first design maps an optimum analog filter into the digital domain; the second approach designs a filter that minimizes in discrete time weighted combination of the variance of the phase error due to noise and the sum square of the deterministic phase error component; the third method uses Kalman filter estimation theory to design a filter composed of a least squares fading memory estimator and a predictor. The last design relies on classical theory, including rules for the design of compensators. Linear analysis is used throughout the article to compare different designs, and includes stability, steady state performance and transient behavior of the loops. Design methodology is not critical when the loop update rate can be made high relative to loop bandwidth, as the performance approaches that of continuous time. For low update rates, however, the miminization method is significantly superior to the other methods
A Theatre Student\u27s Guide to Writing
A very common delusion under which most Theatre students suffer is the idea that because their craft is primarily oral and/or visual that they will not need to worry about developing their writing skills. This is a fallacy. Writing is fundamental in articulating play reviews, analysis and opinons concerning written or visual works, journal articles, theatre history, resumes, grants and proposals. In fact, writing is probably the most important form of communication in the theatre because, without it, there is generally no play to perform. In that plays begin life as written compositions, writing is arguably a very important, in face primary, form of communication in the theatre
Superconducting d-wave junctions: The disappearance of the odd ac components
We study voltage-biased superconducting planar d-wave junctions for arbitrary
transmission and arbitrary orientation of the order parameters of the
superconductors. For a certain orientation of the superconductors the odd ac
components disappear, resulting in a doubling of the Josephson frequency. We
study the sensitivity of this disappearance to orientation and compare with
experiments on grain boundary junctions. We also discuss the possibility of a
current flow parallel to the junction.Comment: 5 pages, 3 figure
Attractions between charged colloids at water interfaces
The effective potential between charged colloids trapped at water interfaces
is analyzed. It consists of a repulsive electrostatic and an attractive
capillary part which asymptotically both show dipole--like behavior. For
sufficiently large colloid charges, the capillary attraction dominates at large
separations.
The total effective potential exhibits a minimum at intermediate separations
if the Debye screening length of water and the colloid radius are of comparable
size.Comment: 8 pages, 1 figure, revised version (one paragraph added) accepted in
JPC
Intrinsic vs. extrinsic anomalous Hall effect in ferromagnets
A unified theory of the anomalous Hall effect (AHE) is presented for
multi-band ferromagnetic metallic systems with dilute impurities. In the clean
limit, the AHE is mostly due to the extrinsic skew-scattering. When the Fermi
level is located around anti-crossing of band dispersions split by spin-orbit
interaction, the intrinsic AHE to be calculated ab initio is resonantly
enhanced by its non-perturbative nature, revealing the extrinsic-to-intrinsic
crossover which occurs when the relaxation rate is comparable to the spin-orbit
interaction energy.Comment: 5 pages including 4 figures, RevTex; minor changes, to appaer in
Phys. Rev. Let
Berry's phase contribution to the anomalous Hall effect of gadolinium
When conduction electrons are forced to follow the local spin texture, the
resulting Berry phase can induce an anomalous Hall effect (AHE). In gadolinium,
as in double-exchange magnets, the exchange interaction is mediated by the
conduction electrons and the AHE may therefore resemble that of chromium
dioxide and other metallic double-exchange ferromagnets. The Hall resistivity,
magnetoresistance, and magnetization of single crystal gadolinium were measured
in fields up to 30 T. Measurements between 2 K and 400 K are consistent with
previously reported data. A scaling analysis for the Hall resistivity as a
function of the magnetization suggests the presence of a Berry's-phase
contribution to the anomalous Hall effect.Comment: 6 pages, 7 figures, submitted to Phys. Rev.
Anomalous Fermi Liquid Behavior of Overdoped High-Tc Superconductors
According to a generic temperature vs. carrier-doping (T-p) phase diagram of
high-temperature superconductors it has been proposed that as doping increases
to the overdoped region they approach gradually a conventional (canonical)
Fermi Liquid. However, Hall effect measurements in several systems reported by
different authors show a still strong \emph{T}-dependence in overdoped samples.
We report here electrical transport measurements of
Y_{1-x}Ca_{x}Ba_{2}Cu_{3}O_{7-delta} thin films presenting a temperature
dependence of the Hall constant, R_H, which does not present a gradual
transition towards the T-independent behavior of a canonical Fermi Liquid.
Instead, the T-dependence passes by a minimum near optimal doping and then
increases again in the overdoped region. We discuss the theoretical predictions
from two representative Fermi Liquid models and show that they can not give a
satisfactory explanation to our data. We conclude that this region of the phase
diagram in YBCO, as in most HTSC, is not a canonical Fermi Liquid, therefore we
call it Anomalous Fermi Liquid.Comment: 9 pages, 12 figures, to be published in Phys. Rev.
Submicrosecond comparison of international clock synchronization by VLBI and the NTS satellite
The intercontinental clock synchronization capabilities of Very Long Baseline Interferometry (VLBI) and the Navigation Technology Satellite (NTS) were compared using both methods to synchronize the Cesium clocks at the NASA Deep Space Net complexes at Madrid, Spain and Goldstone, California. Verification of the accuracy of both systems was examined. The VLBI experiments used the Wideband VLBI Data Acquisition System developed at the NASA Jet Propulsion Laboratory. The NTS Satellites were designed and built by the Naval Research Laboratory used with NTS Timing Receivers developed by the Goddard Space Flight Center. The two methods agreed at about the one-half microsecond level
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