185 research outputs found
On the problems of creating a nuclear-optical frequency standard based on 229Th
The most probable candidate for the role of a nuclear optical standard is the
8.338-eV isomer of the 229mTh isotope of the thorium nucleus. Ways of using the
resonance properties of the electron shell as an optical resonator to create
laser-nuclear technologies necessary for the optical pumping of nuclear isomers
and other manipulations of atomic nuclei leading to the creation of a
next-generation frequency standard and nuclear-optical clocks based on them are
discussed. Deep relations between the physics of resonance electron-nuclear
interactions and the true solution of the thorium puzzle are shown. The article
discusses important principles of resonant optical pumping, such as the
presence of a finite width in the intermediate electronic state, and others
that are usually overlooked with a fatal result for the experiment. The wide
application of the various physics of these processes will predetermine a
revolutionary leap in the development of new laser-nuclear technologies.Comment: 9 pages, 3 figures, submitted to the Proceedings of KVNO-202
CCM – IAG Strategy for Metrology in Absolute Gravimetry: Role of CCM and IAG
The President of the Consultative Committee for Mass and related quantities (CCM) and the President of the International Association of Geodesy (IAG) Commission 2 «Gravity Field» met on March 21, 2013 with the objective to better coordinate the work at the level of both organizations. It was decided to prepare a common strategic document to be used by their respective Working Groups (WG), Sub-commission (SC) and Joint Working Groups (JWG) to clarify future activities and to develop an action plan.The main objective is to define and to harmonize the activities in order to ensure traceability to the SI for gravity measurements at the highest level for metrology and geodesy with-in the framework of the CIPM Mutual Recognition Arrangement (CIPM MRA
Additive Nonparametric Reconstruction of Dynamical Systems from Time Series
We present a nonparametric way to retrieve a system of differential equations
in embedding space from a single time series. These equations can be treated
with dynamical systems theory and allow for long term predictions. We
demonstrate the potential of our approach for a modified chaotic Chua
oscillator.Comment: accepted for Phys. Rev. E, Rapid Com
Application of approximation theory by nonlinear manifolds in Sturm-Liouville inverse problems
We give here some negative results in Sturm-Liouville inverse theory, meaning
that we cannot approach any of the potentials with integrable derivatives
on by an -parametric analytic family better than order
of .
Next, we prove an estimation of the eigenvalues and characteristic values of
a Sturm-Liouville operator and some properties of the solution of a certain
integral equation. This allows us to deduce from [Henkin-Novikova] some
positive results about the best reconstruction formula by giving an almost
optimal formula of order of .Comment: 40 page
Finite jet determination of CR mappings
We prove the following finite jet determination result for CR mappings: Given
a smooth generic submanifold M of C^N, N >= 2, which is essentially finite and
of finite type at each of its points, for every point p on M there exists an
integer l(p), depending upper-semicontinuously on p, such that for every smooth
generic submanifold M' of C^N of the same dimension as M, if h_1 and h_2:
(M,p)->M' are two germs of smooth finite CR mappings with the same l(p) jet at
p, then necessarily their k-jets agree for all positive integers k. In the
hypersurface case, this result provides several new unique jet determination
properties for holomorphic mappings at the boundary in the real-analytic case;
in particular, it provides the finite jet determination of arbitrary
real-analytic CR mappings between real-analytic hypersurfaces in C^N of
D'Angelo finite type. It also yields a new boundary version of H. Cartan's
uniqueness theorem: if Omega and Omega' are two bounded domains in C^N with
smooth real-analytic boundary, then there exists an integer k, depending only
on the boundary of Omega, such that if H_1 and H_2: Omega -> Omega' are two
proper holomorphic mappings extending smoothly up to the boundary of Omega near
some point boundary point p and agreeing up to order k at p, then necessarily
H_1=H_2.Comment: Article in press at Adv. Mat
Self-attraction effect and correction on three absolute gravimeters
The perturbations of the gravitational field due to the mass distribution of
an absolute gravimeter have been studied. The so called Self Attraction Effect
(SAE) is crucial for the measurement accuracy, especially for the International
Comparisons, and for the uncertainty budget evaluation. Three instruments have
been analysed: MPG-2, FG5-238 and IMPG-02. The SAE has been calculated using a
numerical method based on FEM simulation. The observed effect has been treated
as an additional vertical gravity gradient. The correction (SAC) to be applied
to the computed g value has been associated with the specific height level,
where the measurement result is typically reported. The magnitude of the
obtained corrections is of order 1E-8 m/s2.Comment: 14 pages, 8 figures, submitted to Metrologi
REMOVABLE SETS FOR LIPSCHITZ HARMONIC FUNCTIONS ON CARNOT GROUPS
Abstract. Let G be a Carnot group with homogeneous dimension Q ≥ 3 and let L be a sub-Laplacian on G. We prove that the critical dimension for removable sets of Lipschitz L-harmonic functions is (Q − 1). Moreover we construct self-similar sets with positive and finite H Q−1 measure which are removable. 1
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