4,897 research outputs found
Solving magnetostatic field problems with NASTRAN
Determining the three-dimensional magnetostatic field in current-induced situations has usually involved vector potentials, which can lead to excessive computational times. How such magnetic fields may be determined using scalar potentials is reviewed. It is shown how the heat transfer capability of NASTRAN level 17 was modified to take advantage of the new method
The Lerch Zeta Function II. Analytic Continuation
This is the second of four papers that study algebraic and analytic
structures associated with the Lerch zeta function. In this paper we
analytically continue it as a function of three complex variables. We that it
is well defined as a multivalued function on the manifold M equal to C^3 with
the hyperplanes corresponding to integer values of the two variables a and c
removed. We show that it becomes single valued on the maximal abelian cover of
M. We compute the monodromy functions describing the multivalued nature of this
function on M, and determine various of their properties.Comment: 29 pages, 3 figures; v2 notation changes, homotopy action on lef
The mythical concept and untoward consequences of a diagnosis of dysplastic nevus: an overdue tribute to A. Bernard Ackerman, MD
Judicial Analysis of Predation: The Emerging Trends
This Article examines the recent judicial experience in this endeavor. The purposes of the Article are twofold.The first is to describe the current state of the law regarding predation and to discern significant trends that may be developing. The second purpose is to explore the considerations that courts must weigh in evaluating the legal utility of proposed rules that may be valid as a matter of economic theory. Toward these ends,part II of the Article examines the economic and legal context in which litigants present predation claims. Specifically, this part re-views some of the academic debates that have so greatly influenced recent courtroom developments, the statutory framework within which these developments have occurred, and the legacy of Utah Pie Co. v. Continental Baking Co., which is the Supreme Court\u27s most recent predation decision. Part III then explores the standards that courts are applying in the three principal predation contexts-pricing, innovation, and promotion. Finally, part IV examines certain patterns of judicial analysis that are apparent in fifty-seven cases decided during and after 1975, the year in which Professors Areeda and Turner published their seminal article on predatory pricing. These patterns are important and predictive, for they reflect the courts\u27 views about both the frequency and competitive dangers of predation and the administrative costs of attempting to control it. This examination also includes a table summarizing the outcomes of these cases--who won, in which types of cases, at what procedural stage--and a discussion of some economic and administrative considerations underlying those outcomes.\u27 Overall, the analysis in this Article reveals both the legal trends in one specific area of antitrust law--predation-and, more broadly, the methods by which scholarly and judicial analyses can build upon one another to promote more rapid development of an evolving field of legal inquiry
The symplectic origin of conformal and Minkowski superspaces
Supermanifolds provide a very natural ground to understand and handle
supersymmetry from a geometric point of view; supersymmetry in and
dimensions is also deeply related to the normed division algebras.
In this paper we want to show the link between the conformal group and
certain types of symplectic transformations over division algebras. Inspired by
this observation we then propose a new\,realization of the real form of the 4
dimensional conformal and Minkowski superspaces we obtain, respectively, as a
Lagrangian supermanifold over the twistor superspace and a
big cell inside it.
The beauty of this approach is that it naturally generalizes to the 6
dimensional case (and possibly also to the 10 dimensional one) thus providing
an elegant and uniform characterization of the conformal superspaces.Comment: 15 pages, references added, minor change
How to relate the oscillator and Coulomb systems on spheres and pseudospheres?
We show that the oscillators on a sphere and pseudosphere are related, by the
so-called Bohlin transformation, with the Coulomb systems on the pseudosphere:
the even states of an oscillator yields the conventional Coulomb system on
pseudosphere, while the odd states yield the Coulomb system on pseudosphere in
the presence of magnetic flux tube generating half spin. In the higher
dimensions the oscillator and Coulomb(-like) systems are connected in the
similar way. In particular, applying the Kustaanheimo-Stiefel transformation to
the oscillators on sphere and pseudosphere, we obtained the preudospherical
generalization of MIC-Kepler problem describing three-dimensional charge-dyon
system.Comment: 12 pages, Based on talk given at XXIII Colloquium on Group
Theoretical Methods in Physics (July 31-August 5, 2000, Dubna
EUV Spectra of the Full Solar Disk: Analysis and Results of the Cosmic Hot Interstellar Plasma Spectrometer (CHIPS)
We analyze EUV spectra of the full solar disk from the Cosmic Hot
Interstellar Plasma Spectrometer (CHIPS) spanning a period of two years. The
observations were obtained via a fortuitous off-axis light path in the 140 --
270 Angstrom passband. The general appearance of the spectra remained
relatively stable over the two-year time period, but did show significant
variations of up to 25% between two sets of Fe lines that show peak emission at
1 MK and 2 MK. The variations occur at a measured period of 27.2 days and are
caused by regions of hotter and cooler plasma rotating into, and out of, the
field of view. The CHIANTI spectral code is employed to determine plasma
temperatures, densities, and emission measures. A set of five isothermal
plasmas fit the full disk spectra well. A 1 -- 2 MK plasma of Fe contributes
85% of the total emission in the CHIPS passband. The standard Differential
Emission Measures (DEMs) supplied with the CHIANTI package do not fit the CHIPS
spectra well as they over-predict emission at temperatures below log(T) = 6.0
and above log(T) = 6.3. The results are important for cross-calibrating TIMED,
SORCE, SOHO/EIT, and CDS/GIS, as well as the recently launched Solar Dynamics
Observatory.Comment: 27 Pages, 13 Figure
Importance of abortive shock capability with electrogram storage in cardioverter-defibrillator devices
AbstractObjectives. This study evaluates the ability of a third-generation cardioverter-defibrillator to abort energy delivery and the importance of electrogram storage in analyzing the aborted events.Background. In the Cadence Tiered Therapy Defibrillator, when a tachycardia satisfies detection criteria for cardioversion or defibrillation therapy, high voltage capacitors begin charging. The Cadence defibrillator continues monitoring the rhythm during charging and if the rate decreases to below the rate triggering therapy, charging is terminated. This event is registered as an aborted shock. The defibrillator also has the ability to store intracardiac electrogram recordings of the electrical events that precipitate device therapy or aborted shocks.Methods. During a mean follow-up interval of 10 ± 7 months, 55 aborted events were registered by the Cadence defibrillator in 18 of the 49 patients who received it. Thirty-two stored ventricular etectrograms of events leading to aborted shocks were available for analysis in 15 patients.Results. Intracardiac electrogram recordings demonstrated the probable electrical events leading to these aborted shocks included nonsustained ventricular tachycardia (n = 10), nonsustained rapid polymorphic ventricular tachycardia/ventricular fibrillation (n = 2), atrial fibrillation (n = 5), supraventricular tachycardia (n = 2) and electrical noise (n = 13). Eleven patients had a therapeutic intervention initiated as a consequence of the diagnostic information provided by analysis of intracardiac electrogram recordings. Four of the 15 patients had no changes made. During a follow-up period of 9 ± 5 months after therapy was altered, no patient had subsequent aborted shocks. Five patients have had seven appropriate shocks for sustained ventricular tachycardias.Conclusions. The ability of Cadence defibrillator to continue tachycardia sensing during capacitor charging and to abort shock therapy for self-terminating events prevented unnecessary shocks in 18 (37%) of the 49 patients. Intracardiac electrogram recordings were critical for instituting appropriate therapy that may have prevented unnecessary device charging and inappropriate discharges
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