1,364 research outputs found
Europäische Spinne des Jahres 2006: Die Veränderliche Krabbenspinne - Misumena vatia (Clerck, 1757)
Mit der letztjährigen Spinne des Jahres, der Zebraspringspinne Salticus scenicus (Jäger & Kreuels 2005) wurde ein Weg beschritten, Europa arachnologisch zu einen. Ziel war es, möglichst viele Länder bei der Wahl einer europäischen Spinne des Jahres zu beteiligen. 2006 hat die Spinne des Jahres diesen Weg erfolgreich weiter verfolgt
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On radial basis functions
Many sciences and other areas of research and applications from engineering to economics require the approximation of functions that depend on many variables. This can be for a variety of reasons. Sometimes we have a discrete set of data points and we want to find an approximating function that completes this data; another possibility is that precise functions are either not known or it would take too long to compute them explicitly. In this snapshot we want to introduce a particular method of approximation which uses functions called radial basis functions. This method is particularly useful when approximating functions that depend on very many variables. We describe the basic approach to approximation with radial basis functions, including their computation, give several examples of such functions and show some applications
The supersymmetric Higgs sector and B-Bbar mixing for large tan beta
We match the Higgs sector of the most general flavour breaking and CP
violating minimal supersymmetric standard model (MSSM) onto a generic
two-Higgs-doublet model, paying special attention to the definition of tan beta
in the effective theory. In particular no tan beta-enhanced loop corrections
appear in the relation to tan beta defined in the DRbar scheme in the MSSM. The
corrections to the Higgs-mediated flavour-changing amplitudes which result from
this matching are especially relevant for the B_d and B_s mass differences
dM_s,d for minimal flavour violation, where the superficially leading
contribution vanishes. We give a symmetry argument to explain this cancellation
and perform a systematic study of all Higgs-mediated effects, including Higgs
loops. The corrections to dM_s are at most 7% for mu>0 and M_A < 600 if
constraints from other observables are taken into account. For mu<0 they can be
larger, but are always less than about 20%. Contrary to recent claims we do not
find numerically large contributions here, nor do we find any tan beta-enhanced
contributions from loop corrections to the Higgs potential in B^+ -> tau^+ nu
or B -> X_s gamma. We further update supersymmetric loop corrections to the
Yukawa couplings, where we include all possible CP-violating phases and correct
errors in the literature. The possible presence of CP-violating phases
generated by Higgs exchange diagrams is briefly discussed as well. Finally we
provide improved values for the bag factors P^VLL_1, P^LR_2, and P^SLL_1 at the
electroweak scale.Comment: 61 page
-summability and Fourier series of B-splines with respect to their knots
We study the -summability of functions in the -dimensional torus
and so-called -invariant functions. Those are functions
on the torus whose Fourier coefficients depend only on the -norm of
their indices. Such functions are characterized as divided differences that
have as knots for . It leads us to consider the -dimensional
Fourier series of univariate B-splines with respect to its knots, which turns
out to enjoy a simple bi-orthogonality that can be used to obtain an orthogonal
series of the B-spline function
Precise MS-bar light-quark masses from lattice QCD in the RI/SMOM scheme
We compute the conversion factors needed to obtain the MS-bar and RGI up,
down, and strange-quark masses at next-to-next-to-leading order from the
corresponding parameters renormalized in the recently proposed RI/SMOM and
RI/SMOM_gamma_mu renormalization schemes. This is important for obtaining the
MS-bar masses with the best possible precision from numerical lattice-QCD
simulations, because the customary RI(')/MOM scheme is afflicted with large
irreducible uncertainties both on the lattice and in perturbation theory. We
find that the smallness of the known one-loop matching coefficients is
accompanied by even smaller two-loop contributions. From a study of residual
scale dependences, we estimate the resulting perturbative uncertainty on the
light-quark masses to be about 2% in the RI/SMOM scheme and about 3% in the
RI/SMOM_gamma_mu scheme. Our conversion factors are given in fully analytic
form, for general covariant gauge and renormalization point. We provide
expressions for the associated anomalous dimensions.Comment: Added results for the RI/SMOM_gamma_mu scheme and anomalous
dimensions; typos fixed (results unchanged); added reference
Reassessing the discovery potential of the B → K*ℓ⁺ℓ⁻ decays in the large-recoil region: SM challenges and BSM opportunities
We critically examine the potential to disentangle Standard Model (SM) and
New Physics (NP) in and decays,
focusing on the LHCb anomaly, the search for right-handed
currents, and lepton-universality violation. Restricting ourselves to
the large-recoil region, we advocate a parameterisation of the hadronic matrix
elements that separates model-independent information about nonperturbative QCD
from the results of model calculations. We clarify how to estimate corrections
to the heavy-quark limit that would generate a right-handed (virtual) photon in
the contribution to the decay. We then apply this approach to
the discussion of various sets of observables of increasing theoretical
cleanness. First, we show that angular observables in the optimized
basis are, in general, not robust against the long-distance
QCD effects. While a fit to data favours a NP contribution to the semileptonic
operators of the type , this comes at a relatively small
statistical significance of , once power corrections are
properly accounted for. Second, two of these observables, and
are particularly clean at very low and sensitive probes of right-handed
quark currents. We discuss their potential to set stringent bounds on the
Wilson coefficient , especially using data of the electronic mode.
Finally, in light of the recent hint of lepton-universality violation in
, we introduce and investigate new lepton-universality
observables involving angular observables of the muonic and electronic modes
and their zero crossings, and show that, if the effect is of the size suggested
by experiment, these can clearly distinguish between different NP explanations
in terms of underlying semileptonic operators.Comment: We recalculated the results with some updated theoretical input
parameters which cause mild changes in some central values and a slight
increase of the significance of tensions with the SM. Included new Table with
full results with errors obtained using Gaussian distributions of the
nuisance parameters. Some parts of the discussions have also been improve
Eight Weeks of a High Dose of Curcumin Supplementation May Attenuate Performance Decrements Following Muscle-Damaging Exercise
Background: It is known that unaccustomed exercise—especially when it has an eccentric component—causes muscle damage and subsequent performance decrements. Attenuating muscle damage may improve performance and recovery, allowing for improved training quality and adaptations. Therefore, the current study sought to examine the effect of two doses of curcumin supplementation on performance decrements following downhill running. Methods: Sixty-three physically active men and women (21 ± 2 y; 70.0 ± 13.7 kg; 169.3 ± 15.2 cm; 25.6 ± 14.3 body mass index (BMI), 32 women, 31 men) were randomly assigned to ingest 250 mg of CurcuWIN® (50 mg of curcuminoids), 1000 mg of CurcuWIN® (200 mg of curcuminoids), or a corn starch placebo (PLA) for eight weeks in a double-blind, randomized, placebo-controlled parallel design. At the end of the supplementation period, subjects completed a downhill running protocol intended to induce muscle damage. Muscle function using isokinetic dynamometry and perceived soreness was assessed prior to and at 1 h, 24 h, 48 h, and 72 h post-downhill run. Results: Isokinetic peak extension torque did not change in the 200-mg dose, while significant reductions occurred in the PLA and 50-mg groups through the first 24 h of recovery. Isokinetic peak flexion torque and power both decreased in the 50-mg group, while no change was observed in the PLA or 200-mg groups. All the groups experienced no changes in isokinetic extension power and isometric average peak torque. Soreness was significantly increased in all the groups compared to the baseline. Non-significant improvements in total soreness were observed for the 200-mg group, but these changes failed to reach statistical significance. Conclusion: When compared to changes observed against PLA, a 200-mg dose of curcumin attenuated reductions in some but not all observed changes in performance and soreness after completion of a downhill running bout. Additionally, a 50-mg dose appears to offer no advantage to changes observed in the PLA and 200-mg groups
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