3,636 research outputs found
Hilbert-Post completeness for the state and the exception effects
In this paper, we present a novel framework for studying the syntactic
completeness of computational effects and we apply it to the exception effect.
When applied to the states effect, our framework can be seen as a
generalization of Pretnar's work on this subject. We first introduce a relative
notion of Hilbert-Post completeness, well-suited to the composition of effects.
Then we prove that the exception effect is relatively Hilbert-Post complete, as
well as the "core" language which may be used for implementing it; these proofs
have been formalized and checked with the proof assistant Coq.Comment: Siegfried Rump (Hamburg University of Technology), Chee Yap (Courant
Institute, NYU). Sixth International Conference on Mathematical Aspects of
Computer and Information Sciences , Nov 2015, Berlin, Germany. 2015, LNC
Temperature control of the Mariner Venus 67 spacecraft
Temperature control design, instrumentation, and performance characteristics of Mariner 5 spacecraf
Observation of correlations up to the micrometer scale in sliding charge-density waves
High-resolution coherent x-ray diffraction experiment has been performed on
the charge density wave (CDW) system KMoO. The satellite
reflection associated with the CDW has been measured with respect to external
dc currents. In the sliding regime, the satellite reflection displays
secondary satellites along the chain axis which corresponds to correlations up
to the micrometer scale. This super long range order is 1500 times larger than
the CDW period itself. This new type of electronic correlation seems inherent
to the collective dynamics of electrons in charge density wave systems. Several
scenarios are discussed.Comment: 4 pages, 3 figures Typos added, references remove
Carotenoid and SSR marker-based diversity assessment among short duration maize (Zea mays L) genotypes
Based on analysis of variance using a CRD model, significant variation for kernel carotenoid content was found to be present in 25 maize (Zea mays) genotypes. Total carotenoid content was found to be at a minimum (0.94 μg/g) in the white kernel line Sikkim primitive-1, whereas as much as 38.25 μg/g was observed in a dark yellow colored kernel line (1490). TLC profiling of total carotenoids showed that out of 25, 11 lines also had high provitamin-A content, in addition to high kernel carotenoids. Kernel color did not resolve any strong correlation with either total carotenoid content or provitamin-A. Thereby, selection of genotypes for high carotenoid and provitamin-A based on kernel color may not be successful. Jaccard’s similarity coefficients, based on SSR data, were found to vary from 0.17 to 0.97. The highest value of genetic similarity (0.97) was found between Pop31B and Pop31C and therefore they seem to be most similar, whereas inbred lines Pop31D and POB-3, and 1586 and Tarun-1 were most divergent (0.17). The UPGMA den¬drogram constructed using Jaccard similarity coefficients of SSR marker data divided the 25 lines into four groups (A, B, C, and D). Each broad group (Group A and B) was further divided into clusters, thus a total of seven clusters were formed. Cluster strength varied from a minimum of 1 member in cluster III of Group B to a maximum of 5 members in cluster II of Group B. Clustering patterns, in general, revealed that lines with high carotenoid content did not occupy the same cluster. A similar distribution was also observed for lines with a high provitamin-A con¬tent. The marker based clustering pattern therefore did not show strong correlation with quantitative data. Based on total carotenoids and relative provitamin-A content, 11 lines were identified to be a potential source for biofor¬tification of carotene in maize
Numerical Simulations of Dynamos Generated in Spherical Couette Flows
We numerically investigate the efficiency of a spherical Couette flow at
generating a self-sustained magnetic field. No dynamo action occurs for
axisymmetric flow while we always found a dynamo when non-axisymmetric
hydrodynamical instabilities are excited. Without rotation of the outer sphere,
typical critical magnetic Reynolds numbers are of the order of a few
thousands. They increase as the mechanical forcing imposed by the inner core on
the flow increases (Reynolds number ). Namely, no dynamo is found if the
magnetic Prandtl number is less than a critical value .
Oscillating quadrupolar dynamos are present in the vicinity of the dynamo
onset. Saturated magnetic fields obtained in supercritical regimes (either
or ) correspond to the equipartition between magnetic and
kinetic energies. A global rotation of the system (Ekman numbers ) yields to a slight decrease (factor 2) of the critical magnetic
Prandtl number, but we find a peculiar regime where dynamo action may be
obtained for relatively low magnetic Reynolds numbers (). In this
dynamical regime (Rossby number , spheres in opposite direction) at
a moderate Ekman number (), a enhanced shear layer around the inner
core might explain the decrease of the dynamo threshold. For lower
() this internal shear layer becomes unstable, leading to small
scales fluctuations, and the favorable dynamo regime is lost. We also model the
effect of ferromagnetic boundary conditions. Their presence have only a small
impact on the dynamo onset but clearly enhance the saturated magnetic field in
the ferromagnetic parts. Implications for experimental studies are discussed
Combined quantum state preparation and laser cooling of a continuous beam of cold atoms
We use two-laser optical pumping on a continuous atomic fountain in order to
prepare cold cesium atoms in the same quantum ground state. A first laser
excites the F=4 ground state to pump the atoms toward F=3 while a second
pi-polarized laser excites the F=3 -> F'=3 transition of the D2 line to produce
Zeeman pumping toward m=0. To avoid trap states, we implement the first laser
in a 2D optical lattice geometry, thereby creating polarization gradients. This
configuration has the advantage of simultaneously producing Sisyphus cooling
when the optical lattice laser is tuned between the F=4 -> F'=4 and F=4 -> F'=5
transitions of the D2 line, which is important to remove the heat produced by
optical pumping. Detuning the frequency of the second pi-polarized laser
reveals the action of a new mechanism improving both laser cooling and state
preparation efficiency. A physical interpretation of this mechanism is
discussed.Comment: Minor changes according to the recommendations of the referee: -
Corrected Fig.1. - Split the graph of Fig.6 for clarity. - Added one
reference. - Added two remarks in the conclusion. - Results unchange
Controlling magnetization reversal in Co/Pt nanostructures with perpendicular anisotropy
We demonstrate a simple method to tailor the magnetization reversal
mechanisms of Co/Pt multilayers by depositing them onto large area nanoporous
anodized alumina (AAO) with various aspect ratios, A = pore depth/diameter.
Magnetization reversal of composite (Co/Pt)/AAO films with large A is governed
by strong domain-wall pinning which gradually transforms into a
rotation-dominated reversal for samples with smaller A, as investigated by a
first-order reversal curve method in conjunction with analysis of the angular
dependent switching fields. The change of the magnetization reversal mode is
attributed to topographical changes induced by the aspect ratio of the AAO
templates.Comment: 12 pages, 3 figure
A model for electrochemical insertion limited by a phase transition process - eilpt
This paper deals with electrochemical insertion into a cathodic material. New results on modeling of the influence of a solid phase transformation on the shape of voltamograms are presented. The original experiments concern the insertion of sodium into carbon during the cathodic reduction of molten NaF at 1020 °C, but in the present manuscript emphasis on the theoretical aspects of the work is put. Phase transformations during electrochemical insertion are taken into account, with various values for parameters such as the thermodynamic biphase equilibrium potential, the compared diffusion and phase transformation kinetics, and the electrode thickness. The voltamograms calculated present very specific features; some of them have already been observed experimentally in literature
- …