Momentum-resolved evolution of the Kondo lattice into 'hidden-order' in URu2Si2

We study, using high-resolution angle-resolved photoemission spectroscopy, the evolution of the electronic structure in URu2Si2 at the Gamma, Z and X high-symmetry points from the high-temperature Kondo-screened regime to the low-temperature `hidden-order' (HO) state. At all temperatures and symmetry points, we find structures resulting from the interaction between heavy and light bands, related to the Kondo lattice formation. At the X point, we directly measure a hybridization gap of 11 meV already open at temperatures above the ordered phase. Strikingly, we find that while the HO induces pronounced changes at Gamma and Z, the hybridization gap at X does not change, indicating that the hidden-order parameter is anisotropic. Furthermore, at the Gamma and Z points, we observe the opening of a gap in momentum in the HO state, and show that the associated electronic structure results from the hybridization of a light electron band with the Kondo-lattice bands characterizing the paramagnetic state.Comment: Updated published version. Mansucript + Supplemental Material (8 pages, 9 figures). Submitted 16 September 201

Cooperative Management of Ecosystem Services: Coalition Formation, Landscape Structure and Policies

A growing body of literature shows that full-cooperation among farmers to manage productive ecosystem services would yield gains with respect to uncoordinated approaches. The public good feature of these ecosystem services may, however, hinder the emergence of a cooperative solution at the landscape scale. In this paper, we introduce in a coalition formation game a spatially-explicit bioeconomic model of fruit pollination, where pollinaton depends on the distance to the choosen location of natural habitats. We analyse: (i) which coalitions are stable; (ii) what benefits they provide; (iii) how cooperation depends on the initial landscape structure; and (iv) how policy instruments affect cooperation. The theoretical model presents the rationality of cooperation but, due to the detailed heterogeneity and complex spatial interactions among farms, we use a numerical example to determine the stable coalitions. We find that only small coalitions are stable and that the benefits of cooperation decrease when the spatial autocorrelation of fruit tree covers increase. Policy instruments can increase the interest for cooperation but per-hectare payments and minimum participation rules may reduce the habitat area at the margin (by decreasing the stability of coalitions). Price premium for the coalition members increase the habitat area but its budget-effectiveness decreases as the spatial autocorrelation of fruit tree covers increase

Investigations about periodic design for broadband increased sound transmission loss of sandwich panels using 3D-printed models

International audienceTwo types of sandwich panels are designed by using the periodic structure theory. A double-wall panel with mechanical links and a sandwich panel with rectangular core are studied. An oriented optimization of the elastic bending waves' propagation versus the acoustic wavenumbers is achieved by using shifted core walls and by keeping the mass and stiffness of the system constant. Standard and optimized configurations are 3D-printed and sound transmission measurements are carried out by using a facility with an uncoupled reverberant-anechoic configuration. The experimental evidences of enlarged bending band-gaps and deformation mechanisms are proved using a reverse approach based on the acoustic radiation of the panels

The modelling of the flow-induced vibrations of periodic flat and axial-symmetric structures with a wave-based method

International audienceThe stochastic response of periodic flat and axial-symmetric structures, subjected to random and spatially-correlated loads, is here analysed through an approach based on the combination of a wave finite element and a transfer matrix method. Although giving a lower computational cost, the present approach keeps the same accuracy of classic finite element methods. When dealing with homogeneous structures, the accuracy is also extended to higher frequencies, without increasing the time of calculation. Depending on the complexity of the structure and the frequency range, the computational cost can be reduced more than two orders of magnitude. The presented methodology is validated both for simple and complex structural shapes, under deterministic and random loads

A WFE and Hybrid FE/WFE technique for the Forced Response of Stiffened Cylinders

International audienceThe present work shows many aspects concerning the use of a numerical wave-based methodology for the computation of the structural response of periodic structures, focusing on cylinders. Taking into account the periodicity of the system, the Bloch-Floquet theorem can be applied leading to an eigenvalue problem, whose solutions are the waves propagation constants and wavemodes of the periodic structure. Two different approaches are presented, instead, for computing the forced response of stiffened structures. The first one, dealing with a Wave Finite Element (WFE) methodology, proved to drastically reduce the problem size in terms of degrees of freedom, with respect to more mature techniques such as the classic FEM. The other approach presented enables the use of the previous technique even when the whole structure can not be considered as periodic. This is the case when two waveguides are connected through one or more joints and/or different waveguides are connected each other. Any approach presented can deal with deterministic excitations and responses in any point. The results show a good agreement with FEM full models. The drastic reduction of DoF (degrees of freedom) is evident, even more when the number of repetitive substructures is high and the substructures itself is modelled in order to get the lowest number of DoF at the boundaries

DECOUPLING OF ENERGY TRANSMISSION BETWEEN SUBSYSTEMS OF A COMPLEX STRUCTURE

Experimental vibroacoustic measurements are very common for the study of emitted noise reduction and vibration energy isolation of structures. The most important case is when structures are subjected to an aerodynamic excitation as Turbulent Boundary Layer (TBL). In this paper, a preliminary study is performed on the energy transmission between subsystems of a structure subjected to TBL. A numerical test is developed on a three-plates-in-row system at high frequencies, through the application of Statistical Energy Analysis (SEA). Parameters such as surface dimensions, thickness and damping loss factor are evaluated in different configurations for a first design of a testbench used for vibroacoustic measurements in a wind tunnel

Early lean mass sparing effect of high-protein diet with excess leucine during long-term bed rest in women

Muscle inactivity leads to muscle atrophy. Leucine is known to inhibit protein degradation and to promote protein synthesis in skeletal muscle. We tested the ability of a high-protein diet enriched with branched-chain amino acids (BCAAs) to prevent muscle atrophy during long-term bed rest (BR). We determined body composition (using dual energy x-ray absorptiometry) at baseline and every 2-weeks during 60 days of BR in 16 healthy young women. Nitrogen (N) balance was assessed daily as the difference between N intake and N urinary excretion. The subjects were randomized into two groups: one received a conventional diet (1.1 ± 0.03 g protein/kg, 4.9 ± 0.3 g leucine per day) and the other a high protein, BCAA-enriched regimen (1.6 ± 0.03 g protein-amino acid/kg, 11.4 ± 0.6 g leucine per day). There were significant BR and BR × diet interaction effects on changes in lean body mass (LBM) and N balance throughout the experimental period (repeated measures ANCOVA). During the first 15 days of BR, lean mass decreased by 4.1 ± 0.9 and 2.4 ± 2.1% (p < 0.05) in the conventional and high protein-BCAA diet groups, respectively, while at the end of the 60-day BR, LBM decreased similarly in the two groups by 7.4 ± 0.7 and 6.8 ± 2.4%. During the first 15 days of BR, mean N balance was 2.5 times greater (p < 0.05) in subjects on the high protein-BCAA diet than in those on the conventional diet, while we did not find significant differences during the following time intervals. In conclusion, during 60 days of BR in females, a high protein-BCAA diet was associated with an early protein-LBM sparing effect, which ceased in the medium and long term

Giant spin splitting of the two-dimensional electron gas at the surface of SrTiO3

Two-dimensional electron gases (2DEGs) forming at the interfaces of transition metal oxides(1-3) exhibit a range of properties, including tunable insulator-superconductor-metal transitions(4-6), large magnetoresistance(7), coexisting ferromagnetism and superconductivity(8,9), and a spin splitting of a few meV (refs 10,11). Strontium titanate (SrTiO3), the cornerstone of such oxide-based electronics, is a transparent, non-magnetic, wide-bandgap insulator in the bulk, and has recently been found to host a surface 2DEG (refs 12-15). The most strongly confined carriers within this 2DEG comprise two subbands, separated by an energy gap of 90 meV and forming concentric circular Fermi surfaces(12,13,15). Using spin-and angle-resolved photoemission spectroscopy (SARPES), we show that the electron spins in these subbands have opposite chiralities. Although the Rashba effect might be expected to give rise to such spin textures, the giant splitting of almost 100 meV at the Fermi level is far larger than anticipated(16,17). Moreover, in contrast to a simple Rashba system, the spin-polarized subbands are non-degenerate at the Brillouin zone centre. This degeneracy can be lifted by time-reversal symmetry breaking, implying the possible existence of magnetic order. These results show that confined electronic states at oxide surfaces can be endowed with novel, non-trivial properties that are both theoretically challenging to anticipate and promising for technological applications