Flooding and Inundation Modeling in the Great Bay Estuary

As part of this research, FVCOM, a finite-volume coastal ocean numerical hydrodynamic model (Chen, et al., 2003), was implemented into the Great Bay estuary. FVCOM is one of several community models that have been developed for coastal regions, and was selected because it utilizes an unstructured grid to discretize the model domain. The unstructured grid provides the ability to have fine scale resolution near the boundary or coastline and decreased resolution away from the boundary where the flow field is less complicated, resulting in greatly reduced computational expense in less dynamic regions allowing model runs to be completed in much shorter time periods. Grid development also requires that bathymetric data is accurately assigned to grid nodes in such a way that the model itself will be numerically stable. This requires significant development time implementing an appropriate grid mesh (Persson and Strang, 2004) with bathymetry data that has been smoothed to limit inherent numerical noise in the computations. FVCOM was implemented on a grid with finest resolution equaling 30 m, and then tested on a 10 day run with offshore forcing determined analytically by the 8 most energetic semi-diurnal (M2, N2, S2, K2) and diurnal (K1, O1, P1, Q1) tidal constituents at Fort Pt., NH (https://tidesandcurrents.noaa.gov/harcon.html?id=8423898), and including fresh water river fluxes from 6 rivers equivalent to 5 times the average daily discharge (Ward and Bub, 2007). The model was further tested utilizing the 100 year tropical storm event estimated from the North Atlantic Coast Comprehensive Study (NACCS; USACE, 2015), and the highest projected sea level rise scenario for year 2100 estimated by NOAA (http://www.corpsclimate.us/ccaceslcurves.cfm). The numerically stable model indicates that the grid can be used to simulate tidal forcing with maximum projected year storm surge and sea level rise in the Great Bay, and – with further development to include finer (10 m) mesh resolution and inclusion of surface waves and wind forcing – may be able to predict future flooding scenarios based on forecasted storm events and sea level rise

Research Report - October 2009. Elaboration of the Module: Definition of the Programme

Alternative innovative didactic methodology is needed to reduce premature school drop out,particularly of young people at risk of exclusion, such as migrants, ethnic groups and children/teenagers from difficult socio-economic background). The key point is to modify the way to deliver learning. Cultural enrichment through young interestas such as music and art, use of technologies, social competencies, problem-solving skills incomputer science, autonomy and sense of purpose may help childhood and adolescence to achieve an improved engagement in school and a sense of educational accomplishmen

Near-Field Cosmology with Metal-Poor Stars

The oldest, most metal-poor stars in the Galactic halo and satellite dwarf galaxies present an opportunity to explore the chemical and physical conditions of the earliest star forming environments in the Universe. We review the fields of stellar archaeology and dwarf galaxy archaeology by examining the chemical abundance measurements of various elements in extremely metal-poor stars. Focus on the carbon-rich and carbon-normal halo star populations illustrates how these provide insight into the Population III star progenitors responsible for the first metal enrichment events. We extend the discussion to near-field cosmology, which is concerned with the formation of the first stars and galaxies and how metal-poor stars can be used to constrain these processes. Complementary abundance measurements in high-redshift gas clouds further help to establish the early chemical evolution of the Universe. The data appear consistent with the existence of two distinct channels of star formation at the earliest times.Comment: 126 pages, 12 figures, Annual Review of Astronomy and Astrophysics (ARA&A), in pres

Morphic words and equidistributed sequences

The problem we consider is the following: Given an infinite word $w$ on an ordered alphabet, construct the sequence $\nu_w=(\nu[n])_n$, equidistributed on $[0,1]$ and such that $\nu[m]<\nu[n]$ if and only if $\sigma^m(w)<\sigma^n(w)$, where $\sigma$ is the shift operation, erasing the first symbol of $w$. The sequence $\nu_w$ exists and is unique for every word with well-defined positive uniform frequencies of every factor, or, in dynamical terms, for every element of a uniquely ergodic subshift. In this paper we describe the construction of $\nu_w$ for the case when the subshift of $w$ is generated by a morphism of a special kind; then we overcome some technical difficulties to extend the result to all binary morphisms. The sequence $\nu_w$ in this case is also constructed with a morphism. At last, we introduce a software tool which, given a binary morphism $\varphi$, computes the morphism on extended intervals and first elements of the equidistributed sequences associated with fixed points of $\varphi$

Electronic nematic susceptibility of iron-based superconductors

We review our recent experimental results on the electronic nematic phase in electron- and hole-doped BaFe$_2$As$_2$ and FeSe. The nematic susceptibility is extracted from shear-modulus data (obtained using a three-point-bending method in a capacitance dilatometer) using Landau theory and is compared to the nematic susceptibility obtained from elastoresistivity and Raman data. FeSe is particularly interesting in this context, because of a large nematic, i.e., a structurally distorted but paramagnetic, region in its phase diagram. Scaling of the nematic susceptibility with the spin lattice relaxation rate from NMR, as predicted by the spin-nematic theory, is found in both electron- and hole-doped BaFe$_2$As$_2$, but not in FeSe. The intricate relationship of the nematic susceptibility to spin and orbital degrees of freedom is discussed.Comment: Invited review article for a special issue on Fe-based superconductors in Comptes Rendus Physiqu

Nematicity, magnetism and superconductivity in FeSe

Iron-based superconductors are well known for their complex interplay between structure, magnetism and superconductivity. FeSe offers a particularly fascinating example. This material has been intensely discussed because of its extended nematic phase, whose relationship with magnetism is not obvious. Superconductivity in FeSe is highly tunable, with the superconducting transition temperature, $T_\mathrm{c}$, ranging from 8 K in bulk single crystals at ambient pressure to almost 40 K under pressure or in intercalated systems, and to even higher temperatures in thin films. In this topical review, we present an overview of nematicity, magnetism and superconductivity, and discuss the interplay of these phases in FeSe. We focus on bulk FeSe and the effects of physical pressure and chemical substitutions as tuning parameters. The experimental results are discussed in the context of the well-studied iron-pnictide superconductors and interpretations from theoretical approaches are presented.Comment: Topical Review submitted to Journal of Physics: Condensed Matte