155,763 research outputs found
Helium window for shock-tube monochromators
Technique for coupling vacuum ultraviolet monochromator to shock tube to avoid loss of high energy ultraviolet light during quantitative measurements is described. System consists of helium gas window pumping through small aperture in entrance pupil of monochromator. Diagram of equipment and principles of operation are presented
Anomalous Hall effect in the Co-based Heusler compounds CoFeSi and CoFeAl
The anomalous Hall effect (AHE) in the Heusler compounds CoFeSi and
CoFeAl is studied in dependence of the annealing temperature to achieve a
general comprehension of its origin. We have demonstrated that the crystal
quality affected by annealing processes is a significant control parameter to
tune the electrical resistivity as well as the anomalous Hall
resistivity . Analyzing the scaling behavior of in
terms of points to a temperature-dependent skew scattering as the
dominant mechanism in both Heusler compounds
Genealogical constructions of population models
Representations of population models in terms of countable systems of
particles are constructed, in which each particle has a `type', typically
recording both spatial position and genetic type, and a level. For finite
intensity models, the levels are distributed on , whereas in the
infinite intensity limit , at each time , the
joint distribution of types and levels is conditionally Poisson, with mean
measure where denotes Lebesgue measure and is a measure-valued population process. The time-evolution of the levels
captures the genealogies of the particles in the population.
Key forces of ecology and genetics can be captured within this common
framework. Models covered incorporate both individual and event based births
and deaths, one-for-one replacement, immigration, independent `thinning' and
independent or exchangeable spatial motion and mutation of individuals. Since
birth and death probabilities can depend on type, they also include natural
selection. The primary goal of the paper is to present particle-with-level or
lookdown constructions for each of these elements of a population model. Then
the elements can be combined to specify the desired model. In particular, a
non-trivial extension of the spatial -Fleming-Viot process is
constructed
Signatures of Spherical Compactification at the LHC
TeV-scale extra dimensions may play an important role in electroweak or
supersymmetry breaking. We examine the phenomenology of such dimensions,
compactified on a sphere , , and show that they possess distinct
features and signatures. For example, unlike flat toroidal manifolds, spheres
do not trivially allow fermion massless modes. Acceptable phenomenology then
generically leads to "non-universal" extra dimensions with "pole-localized"
4- fermions; the bosonic fields can be in the bulk. Due to spherical
symmetry, some Kaluza-Klein (KK) modes of bulk gauge fields are either stable
or extremely long-lived, depending on the graviton KK spectrum. Using precision
electroweak data, we constrain the lightest gauge field KK modes to lie above
TeV. We show that some of these KK resonances are within the reach
of the LHC in several different production channels. The models we study can be
uniquely identified by their collider signatures.Comment: 21 pages, 5 fig
Similarity parameters for radiative energy transfer in isothermal and non-isothermal gas mixtures
The similarity groups for multicomponent, reacting gas mixtures with radiative
energy transport are derived (Section I). The resulting relations are used to consider
the feasibility if scaling for flow processes with radiative energy transport under
highly simplified conditions (Sections 2 and 3). Next the scaling parameters are
derived for radiant energy emission from isobaric and isothermal gases for
arbitrary opacities and various spectral line and molecular band models (Section 4).
Scaling parameters for radiant energy emission from isobaric but non-isothermal
systems are discussed for arbitrary opacities and various spectral line and molecular
band models under the restrictions imposed on the allowed temperature profiles for
dispersion and Doppler lines by the Eddington-Barbier approximation (Section 5).
Finally, we consider the radiative scaling properties for representative
temperature profiles for both collision-broadened and Doppler-broadened line
profiles on the basis if exact numerical calculations that we have performed for a
rotational spectral line belonging to a molecular vibration-rotation band. (Section
6). It appears that simple scaling rules generally constitute a fair approximation
for dispersion lines in non-isothermal systems but that corresponding relations
apply to lines with Doppler contour only in the transparent gas regime
An SO(3)-monopole cobordism formula relating Donaldson and Seiberg-Witten invariants
We prove an analogue of the Kotschick-Morgan conjecture in the context of
SO(3) monopoles, obtaining a formula relating the Donaldson and Seiberg-Witten
invariants of smooth four-manifolds using the SO(3)-monopole cobordism. The
main technical difficulty in the SO(3)-monopole program relating the
Seiberg-Witten and Donaldson invariants has been to compute intersection
pairings on links of strata of reducible SO(3) monopoles, namely the moduli
spaces of Seiberg-Witten monopoles lying in lower-level strata of the Uhlenbeck
compactification of the moduli space of SO(3) monopoles [arXiv:dg-ga/9710032].
In this monograph, we prove --- modulo a gluing theorem which is an extension
of our earlier work in [arXiv:math/9907107] --- that these intersection
pairings can be expressed in terms of topological data and Seiberg-Witten
invariants of the four-manifold. This conclusion is analogous to the
Kotschick-Morgan conjecture concerning the wall-crossing formula for Donaldson
invariants of a four-manifold with ; that wall-crossing formula and
the resulting structure of Donaldson invariants for four-manifolds with
were established, assuming the Kotschick-Morgan conjecture, by
Goettsche [arXiv:alg-geom/9506018] and Goettsche and Zagier
[arXiv:alg-geom/9612020]. In this monograph, we reduce the proof of the
Kotschick-Morgan conjecture to an extension of previously established gluing
theorems for anti-self-dual SO(3) connections (see [arXiv:math/9812060] and
references therein). Since the first version of our monograph was circulated,
applications of our results have appeared in the proof of Property P for knots
by Kronheimer and Mrowka [arXiv:math/0311489] and work of Sivek on Donaldson
invariants for symplectic four-manifolds [arXiv:1301.0377].Comment: x + 229 page
Daubert\u27s Significance
The authors review and note the limited reach of Daubert v. Merrell Dow Pharmaceuticals. They also address its implications for concerned non-lawyers
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