Crystal-field effects in the mixed-valence compounds Yb2M3Ga9 (M= Rh, Ir)

Magnetic susceptibility, heat capacity, and electrical resistivity measurements have been carried out on single crystals of the intermediate valence compounds Yb2Rh3Ga9 and Yb2Ir3Ga9. These measurements reveal a large anisotropy due apparently to an interplay between crystalline electric field (CEF) and Kondo effects. The temperature dependence of magnetic susceptibility can be modelled using the Anderson impurity model including CEF within an approach based on the Non-Crossing Approximation.Comment: Accepted to Phys. Rev.

On the origin of heavy quasiparticles in LiV_2O_4

An explanation is provided for the heavy quasiparticle excitations in LiV_2O_4. It differs considerably from that of other known heavy-fermion systems. Main ingredients of our theory are the cubic spinel structure of the material and strong short-range correlations of the d electrons. The large gamma-coefficient is shown to result from excitations of Heisenberg spin 1/2 rings and chains. The required coupling constant is calculated from LDA+U calculations and is found to be of the right size. Also the calculated Sommerfeld-Wilson ratio is reasonably close to the observed one.Comment: REVTEX, 5 pages, 2 figure

Life in the Atacama — Year 2: Geologic reconnaissance through long-range roving and implications on the search for life

The Life in the Atacama-2004 project, which included geological, morphological, and mineralogical mapping through combined satellite, field-based, and microscopic perspectives and long-range roving, led to the localization of potential habitats

Participation in Transition(s):Reconceiving Public Engagements in Energy Transitions as Co-Produced, Emergent and Diverse

This paper brings the transitions literature into conversation with constructivist Science and Technology Studies (STS) perspectives on participation for the first time. In doing so we put forward a conception of public and civil society engagement in sustainability transitions as co-produced, relational, and emergent. Through paying close attention to the ways in which the subjects, objects, and procedural formats of public engagement are constructed through the performance of participatory collectives, our approach offers a framework to open up to and symmetrically compare diverse and interconnected forms of participation that make up wider socio-technical systems. We apply this framework in a comparative analysis of four diverse cases of civil society involvement in UK low carbon energy transitions. This highlights similarities and differences in how these distinct participatory collectives are orchestrated, mediated, and subject to exclusions, as well as their effects in producing particular visions of the issue at stake and implicit models of participation and ‘the public’. In conclusion we reflect on the value of this approach for opening up the politics of societal engagement in transitions, building systemic perspectives of interconnected ‘ecologies of participation’, and better accounting for the emergence, inherent uncertainties, and indeterminacies of all forms of participation in transitions

Verdienmodellen voor natuurinclusieve landbouw:Wat ondernemers al doen, en wat de overheid kan doen om opschaling te bevorderen

De Rijksnatuurvisie 2014 breekt een lans voor natuurinclusieve landbouw waarbij veel nadruk ligt op de rol van markt en maatschappij. Zulke landbouw behelst wat de nota noemt ‘natuurcombinaties’ waarbij natuur en economische activiteiten met elkaar vervlochten zijn. Een natuurinclusieve landbouw heeft een wezenlijk andere oriëntatie dan gangbare landbouw. In dit essay gaan we in op de voorwaarden waaronder natuurinclusieve verdienmodellen op middellange termijn op grote schaal kunnen worden gerealiseerd. Dit wordt uiteengezet op basis van de ervaringen van koplopers, die al langer aan natuurinclusieve landbouw doen

Spectroscopic results from the Life in the Atacama (LITA) project 2004 field season

Analysis of spectroscopy datasets from rover field tests in the Atacama Desert (Chile), focusing on the composition of the surface and identification of potential habitats for life

Magnetic Structure of Heavy Fermion Ce2RhIn8

Magnetic structure of the heavy fermion antiferromagnet Ce2RhIn8 is determined using neutron diffraction.Comment: 4 pages, 3 figures, 1 tabl

Compressibility of CeMIn5Ce M In_5 and Ce2MIn8Ce_2 M In_8 (M = Rh, Ir and Co) Compounds

The lattice parameters of the tetragonal compounds Ce$M$In$_{5}$ and Ce$_{2}M$In$_{8}$($M=$Rh, Ir and Co) have been studied as a function of pressure up to 15 GPa using a diamond anvil cell under both hydrostatic and quasihydrostatic conditions at room temperature. The addition of $M$In$_{2}$ layers to the parent CeIn$_{3}$ compound is found to stiffen the lattice as the 2-layer systems (average of bulk modulus values $B_{0}$ is 70.4 GPa) have a larger $B_{0}$ than CeIn$_{3}$ (67 GPa), while the 1-layer systems with the are even stiffer (average of $B_{0}$ is 81.4 GPa). Estimating the hybridization using parameters from tight binding calculations shows that the dominant hybridization is $fp$ in nature between the Ce and In atoms. The values of $V_{pf}$ at the pressure where the superconducting transition temperature $T_{c}$ reaches a maximum is the same for all Ce$M$In$_{5}$ compounds. By plotting the maximum values of the superconducting transition temperature $T_{c}$ versus $c/a$ for the studied compounds and Pu-based superconductors, we find a universal $T_{c}$ versus $c/a$ behavior when these quantities are normalized appropriately. These results are consistent with magnetically mediated superconductivity.Comment: Updated version resubmitted to Phys. Rev.

Searching for life with rovers: exploration methods and science results from the 2004 field campaign of the “Life in the Atacama” project and applications to future Mars Missions

LITA develops and field tests a long-range automated rover and a science payload to search for microbial life in the Atacama. The Atacama's evolution provides a unique training ground for designing and testing exploration strategies and life detection methods for the search for life on Mars