19,827 research outputs found
A new Miconia (Melastomatacaeae) from Bolivia, with remarks on angular-branched species in the Andes
A new species of Melastomataceae frorm Bolivia is described, illustrated and placed in a phenetic context within Miconia, a genus of 1000 species and about 2000 published names. Miconia quadrialata is readily distinguished from its Congeners by two-colored leaves and sharply four-angular
and winged branchlets. A search for quadrangular-branched miconias revealed that 12 of 15 such species (in four sections), including the new species, occur in cloud forest in the Andes, raising the question of the adaptive significance of quadrangular branchlets
Baryogenesis at the Electroweak Phase Transition for a SUSY Model with a Gauge Singlet
SUSY models with a gauge singlet easily allow for a strongly first order
electroweak phase transition (EWPT). We discuss the wall profile, in particular
transitional CP violation during the EWPT. We calculate CP violating source
terms for the charginos in the WKB approximation and solve the relevant
transport equations to obtain the generated baryon asymmetry.Comment: 5 pages, 6 figures. To appear in the Proceedings of Strong and
Electroweak Matter 2000 (SEWM2000), Marseilles; a reference adde
A multiple factor model for European stocks
We present an empirical study focusing on the estimation of a fundamental multi-factor model for a universe of European stocks. Following the approach of the BARRA model, we have adopted a cross-sectional methodology. The proportion of explained variance ranges from 7.3% to 66.3% in the weekly regressions with a mean of 32.9%. For the individual factors we give the percentage of the weeks when they yielded statistically significant influence on stock returns. The best explanatory power â apart from the dominant country factors â was found among the statistical constructs âsuccessâ and âvariability in marketsâ.Vorgestellt wird eine empirische Studie, welche die SchĂ€tzung eines fundamentalen Multi-Faktor-Modells fĂŒr ein Universum europĂ€ischer Aktien beinhaltet. Als Methode wurde in Anlehnung an die Vorgehensweise im BARRA-Modell der Querschnittsanalyse der Vorzug gegeben. Der Anteil der erklĂ€rten Varianz belĂ€uft sich in den wöchentlichen Regressionen auf 7,3% bis 66,3% bei einem Durchschnitt von 32,9%. FĂŒr die einzelnen Faktoren wird die HĂ€ufigkeit angegeben, mit der sie sich in den Regressionen signifikant erwiesen haben. Den höchsten ErklĂ€rungsgehalt im Untersuchungszeitraum hatten LĂ€nderfaktoren, aber auch Konstrukte wie âSuccessâ oder âVariability in Marketsâ
Search for Higgs and New Phenomena at Colliders
The present status of searches for the Higgs boson(s) and new phenomena is
reviewed. The focus is on analyses and results from the current runs of the
HERA and Tevatron experiments. The LEP experiments have released their final
combined MSSM Higgs results for this conference. Also included are results from
sensitivity studies of the LHC experiments and lepton flavour violating
searches from the B factories, KEKB and PEP-II.Comment: XXII International Symposium on Lepton-Photon Interactions at High
Energy (11 pages, 16 figures, 2 tables
Creative destruction and asset prices
This paper introduces Schumpeter's idea of creative destruction into asset pricing. The key point of our model is that small and value firms are more likely destroyed during technological revolutions, resulting into higher expected returns for these stocks. A two-factor model including market return and patent activity growth - the proxy for creative destruction risk - accounts for a large portion of the cross-sectional variation of size and book-to-market sorted portfolios and prices HML and SMB. The expected return difference between assets with the highest and lowest exposure to creative destruction risk amounts to 8.6 percent annually. --creative destruction,asset pricing,size and value premium,patents
Implementation of accurate broadband steering vectors for broadband angle of arrival estimation
Motivated by accurate broadband steering vector requirements for applications such as broadband angle of arrival estimation, we review fractional delay filter designs. A common feature across these are their rapidly decreasing performance as the Nyquist rate is approached. We propose a filter bank based approach, which operates standard fractional delay filters on a series of frequency-shifted subband signals, such that they appear in the filtersâ lowpass region. We demonstrate the appeal of this approach in simulations
Bessel beams of two-level atoms driven by a linearly polarized laser field
We study Bessel beams of two-level atoms that are driven by a linearly
polarized laser field. Starting from the Schroedinger equation, we determine
the states of two-level atoms in a plane-wave field respecting propagation
directions both of the atom and the field. For such laser-driven two-level
atoms, we construct Bessel beams beyond the typical paraxial approximation. We
show that the probability density of these atomic beams obtains a non-trivial,
Bessel-squared-type behavior and can be tuned under the special choice of the
atom and laser parameters, such as the nuclear charge, atom velocity, laser
frequency, and propagation geometry of the atom and laser beams. Moreover, we
spatially and temporally characterize the beam of hydrogen and selected
(neutral) alkali-metal atoms that carry non-zero orbital angular momentum
(OAM). The proposed spatiotemporal Bessel states (i) are able to describe, in
principle, twisted states of any two-level system which is driven by the
radiation field and (ii) have potential applications in atomic, nuclear
processes and quantum communication.Comment: 13 pages, 5 figures, appeared as a EPJD highlight on Thursday, 01
August 2013
http://www.epj.org/index.php?option=com_content&view=article&id=684%3Aepjd-highlight-novel-beams-made-of-twisted-atoms&catid=112%3Aepj-d&Itemid=466&lang=e
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