Prospects for Dark Energy Evolution: a Frequentist Multi-Probe Approach

A major quest in cosmology is the understanding of the nature of dark energy. It is now well known that a combination of cosmological probes is required to break the underlying degeneracies on cosmological parameters. In this paper, we present a method, based on a frequentist approach, to combine probes without any prior constraints, taking full account of the correlations in the parameters. As an application, a combination of current SNIa and CMB data with an evolving dark energy component is first compared to other analyses. We emphasise the consequences of the implementation of the dark energy perturbations on the result for a time varying equation of state. The impact of future weak lensing surveys on the measurement of dark energy evolution is then studied in combination with future measurements of the cosmic microwave background and type Ia supernovae. We present the combined results for future mid-term and long-term surveys and confirm that the combination with weak lensing is very powerful in breaking parameter degeneracies. A second generation of experiment is however required to achieve a 0.1 error on the parameters describing the evolution of dark energy.Comment: Submitted to Astronomy & Astrophysics 14 pages, 8 figure

Parareal in time 3D numerical solver for the LWR Benchmark neutron diffusion transient model

We present a parareal in time algorithm for the simulation of neutron diffusion transient model. The method is made efficient by means of a coarse solver defined with large time steps and steady control rods model. Using finite element for the space discretization, our implementation provides a good scalability of the algorithm. Numerical results show the efficiency of the parareal method on large light water reactor transient model corresponding to the Langenbuch-Maurer-Werner (LMW) benchmark [1]

Coefficient of performance at maximum figure of merit and its bounds for low-dissipation Carnot-like refrigerators

The figure of merit for refrigerators performing finite-time Carnot-like cycles between two reservoirs at temperature $T_h$ and $T_c$ ($<T_h$) is optimized. It is found that the coefficient of performance at maximum figure of merit is bounded between 0 and $(\sqrt{9+8\varepsilon_c}-3)/2$ for the low-dissipation refrigerators, where $\varepsilon_c =T_c/(T_h-T_c)$ is the Carnot coefficient of performance for reversible refrigerators. These bounds can be reached for extremely asymmetric low-dissipation cases when the ratio between the dissipation constants of the processes in contact with the cold and hot reservoirs approaches to zero or infinity, respectively. The observed coefficients of performance for real refrigerators are located in the region between the lower and upper bounds, which is in good agreement with our theoretical estimation.Comment: 5 journal pages, 3 figure

Dental Abnormalities and Early Diagnosis of Hyperphosphatasemia

Dental hard tissue abnormalities have never been described as part of the symptoms associated with hyperphosphatasemia. Fourteen teeth obtained from a young man, who had a mild form of hyperphosphatasemia, were analyzed using scanning electron microscopy (SEM), secondary ion mass spectroscopy (SIMS), X-ray diffraction (XRD), and infrared (IR) spectroscopy. SEM revealed a thin enamel, presenting a prismatic structure with many pits, and atypical cementum and dentin showing numerous resorption areas. The X-ray diffractograms revealed poorly crystallinehydroxyapatite associated with α-tricalcium phosphate and magnesium hydroxide phases. SIMS data showed high Ca concentrations: 40.5 weight % {wt%; standard deviation (SD) = 0.13) and 42.5 wt% (SD = 1.03) in enamel and dentin respectively, and high Ca/P weight ratios: 2.28 in the enamel, 2.65 in the dentin. The lack of crystallinity may be linked to the high content of proteins and magnesium adsorbed onto apatite. This study demonstrates the need for thorough radiographical and biological investigations for skeletal abnormalities, even in the absence of systemic symptoms, when generalized dental abnormalities of both enamel and dentin are observed

A Very Low Resource Language Speech Corpus for Computational Language Documentation Experiments

Most speech and language technologies are trained with massive amounts of speech and text information. However, most of the world languages do not have such resources or stable orthography. Systems constructed under these almost zero resource conditions are not only promising for speech technology but also for computational language documentation. The goal of computational language documentation is to help field linguists to (semi-)automatically analyze and annotate audio recordings of endangered and unwritten languages. Example tasks are automatic phoneme discovery or lexicon discovery from the speech signal. This paper presents a speech corpus collected during a realistic language documentation process. It is made up of 5k speech utterances in Mboshi (Bantu C25) aligned to French text translations. Speech transcriptions are also made available: they correspond to a non-standard graphemic form close to the language phonology. We present how the data was collected, cleaned and processed and we illustrate its use through a zero-resource task: spoken term discovery. The dataset is made available to the community for reproducible computational language documentation experiments and their evaluation.Comment: accepted to LREC 201

Chemical and mineralogical characterization and ceramic suitability of raw feldspathic materials from Dschang (Cameroon)

The chemical and mineralogical characterization of raw feldspathic materials from Dschang (Cameroon) was realized by means of X-ray diffraction, differential thermal analyses, optical and scanning electron microscopies, and analytical techniques. It was found that these materials consist of albite (43 ± 3 wt.%), microcline (41 and 26 wt.%), quartz (14.5 ± 1.5 wt.%), plagioclase (oligoclase type) (6 and 12 wt.%) and a minor content of biotite. The amount of fluxing oxides is about 12 wt.% and those of pigments are quasi-null. The ceramic suitability of these materials was assessed in the light of the obtained chemical data and physical characteristics (fusibility, viscosity, colour). The results showed that these raw materials are convenient, as fluxing compounds, for manufacturing white ceramic.KEY WORDS: Raw feldspathic materials, Mineralogy, Chemical composition, Ceramic suitability, Cameroon   Bull. Chem. Soc. Ethiop. 2010, 24(1), 39-46

Programming the assembly of carboxylic acid-functionalised hybrid polyoxometalates

We report here the straightforward synthesis and characterisation of a series Anderson-type hybrid polyoxometalates in high yield, functionalised with carboxylic acid following the reaction of anhydride precursors with the starting hybrid cluster ([n-N(C4H9)4]3[MnMo6O18((OCH2)3CNH2)2]). Seven new structures have been obtained, five of which have acid-terminated ligands. Six of these structures have been isolated with a yield higher than 80% with high purity. This reaction is limited by the bulkiness of the anhydride used; this effect can be employed to selectively synthesise one isomer out of three other possibilities. The acid groups and aromatic platforms attached to the clusters can act as building tools to bridge several length scales and engineer molecular packing within the crystal structure. The presence of acids should also change the hydrophilicity of the clusters, and therefore the way they interact with hydrophilic surfaces. We also show a potential relationship between the acid group interaction in the packing diagram and the cluster’s tendency to interact with a hydrophilic surface. In addition to reporting a derived synthetic path to new acid-terminated Mn-Anderson-type hybrids, we describe here a new way to program self-assembly motifs of these compounds in the crystal structure and at interfaces

The Use of the Signal at an Optimal Distance from the Shower Core as a Surrogate for Shower Size

When analysing data from air-shower arrays, it has become common practice to use the signal at a considerable distance from the shower axis (ropt) as a surrogate for the size of the shower. This signal, S(ropt), can then be related to the primary energy in a variety of ways. After a brief review of the reasons behind the introduction of ropt laid out in a seminal paper by Hillas in 1969, it will be shown that ropt, is a more effective tool when detectors are laid out on a triangular grid than when detectors are deployed on a square grid. This result may have implications for explaining the differences between the flux observed by the Auger and Telescope collaborations above 10\,EeV and should be kept in mind when designing new shower arrays

The Use of the Signal at an Optimal Distance from the Shower Core as a Surrogate for Shower Size

When analysing data from air-shower arrays, it has become common practice to use the signal at a considerable distance from the shower axis (_opt) as a surrogate for the size of the shower. This signal, (_opt), can then be related to the primary energy in a variety of ways. After a brief review of the reasons behind the introduction of opt laid out in a seminal paper by Hillas in 1969, it will be shown that _opt, is a more effective tool when detectors are laid out on a triangular grid than when detectors are deployed on a square grid. This result may have implications for explaining the differences between the flux observed by the Auger and Telescope collaborations above 10 EeV and should be kept in mind when designing new shower arrays

Kinetic theory of point vortex systems from the Bogoliubov-Born-Green-Kirkwood-Yvon hierarchy

Kinetic equations are derived from the Bogoliubov-Born-Green-Kirkwood-Yvon (BBGKY) hierarchy for point vortex systems in an infinite plane. As the level of approximation for the Landau equation, the collision term of the kinetic equation derived coincides with that by Chavanis ({\it Phys. Rev. E} {\bf 64}, 026309 (2001)). Furthermore, we derive a kinetic equation corresponding to the Balescu-Lenard equation for plasmas, using the theory of the Fredholm integral equation. For large $N$, this kinetic equation is reduced to the Landau equation above.Comment: 10 pages, No figures. To be published in Physical Review E, 76-