Control of the colossal magnetoresistance by strain effect in Nd0.5_{0.5}Ca0.5_{0.5}MnO3_{3} thin films

Thin films of Nd$_{0.5}$Ca$_{0.5}$MnO$_{3}$ manganites with colossal magnetoresistance (CMR) properties have been synthesized by the Pulsed Laser Deposition technique on (100)-SrTiO$_{3}$. The lattice parameters of these manganites and correlatively their CMR properties can be controlled by the substrate temperature $T_{S}$. The maximum CMR effect at 75K, calculated as the ratio $\rho (H=0T)/\rho (H=7T)$ is 10$^4$ for a deposition temperature of $T_{S}=680$ degC. Structural studies show that the Nd$_{0.5}$Ca$_{0.5}$MnO$_{3}$ film is single phase, [010]-oriented and has a pseudocubic symmetry of the perovskite subcell with a=3.77$\AA$ at room temperature. We suggest that correlation between lattice parameters, CMR and substrate temperature $T_{S}$ result mainly from substrate-induced strains which can weaken the charge-ordered state at low temperature.Comment: 9 pages, 4 figures. To be published in Applied Physics Letter

Interplay between mesoscopic phase separation and bulk magnetism in the layered NaxCoO2

Specific heat of the layered NaxCoO2 (x=0.65, 0.70 and 0.75) oxides has been measured in the temperature range of 3-360 K and magnetic field of 0 and 9 T. The analysis of data, assuming the combined effect of inter-layer superexchange and the phase separation into mesoscopic magnetic domains with localized spins embedded in a matrix with itinerant electronic character, suggests that the dominant contribution to the specific heat in the region of short-range ordering is mediated by quasi-2D antiferromagnetic clusters, perpendicular to the CoO2 layers

Bedrijfsspecifieke fosfaatgebruiksnormen (BEP): onderbouwing en verkenning in de praktijk

De Nederlandse overheid heeft met de Europese Commissie afgesproken dat in 2015 het gebruik van fosfaat als meststof overeen zal komen met de hoeveelheid fosfaat in geoogst gewas (evenwichtsbemesting). Het gebruik van fosfaatmeststoffen is vastgelegd in generieke normen per gewas. Deze normen zijn gebaseerd op een gemiddelde fosfaatonttrekking in Nederland. Het doel van deze studie is om te verkennen of bedrijfsspecifieke fosfaatgebruiksnormen in de praktijk te bepalen is, uitgaande van gronden met een neutrale P-toestand. Bij de uitwerking is aangesloten op bestaande en al geaccepteerde (door sector en overheid) managementinstrumenten in de melkveehouderij, namelijk de ‘Handreiking bedrijfsspecifieke excretie melkvee’. Koeien & Kansen heeft op basis van de Handreiking een managementinstrument gemaakt (BEX)

Application of mineralogical, petrological and geochemical tools for evaluating the palaeohdrogeological evolution of the PADAMOT study sites

The role of Work Package (WP) 2 of the PADAMOT project – ‘Palaeohydrogeological Data Measurements’ - has been to study late-stage fracture mineral and water samples from groundwater systems in Spain, Sweden, United Kingdom and the Czech Republic, with the aim of understanding the recent palaeohydrogeological evolution of these groundwater systems. In particular, the project sought to develop and evaluate methods for obtaining information about past groundwater evolution during the Quaternary (about the last 2 million years) by examining how the late-stage mineralization might record mineralogical, petrographical and geochemical evidence of how the groundwater system may have responded to past geological and climatological changes. Fracture-flow groundwater systems at six European sites were studied: • Melechov Hill, in the Bohemian Massif of the Czech Republic: a shallow (0-100 m) dilute groundwater flow system within the near-surface weathering zone in fractured granitic rocks; • Cloud Hill, in the English Midlands: a (~100 m) shallow dilute groundwater flow system in fractured and dolomitized Carboniferous limestone; • Los Ratones, in southwest Spain: an intermediate depth (0-500 m) dilute groundwater flow system in fractured granitic rocks; • Laxemar, in southeast Sweden: a deep (0-1000 m) groundwater flow system in fractured granitic rocks. This is a complex groundwater system with potential recharge and flushing by glacial, marine, lacustrine and freshwater during the Quaternary; • Sellafield, northwest England: a deep (0-2000 m) groundwater flow system in fractured Ordovician low-grade metamorphosed volcaniclastic rocks and discontinuous Carboniferous Limestone, overlain by a Permo-Triassic sedimentary sequence with fracture and matrix porosity. This is a complex coastal groundwater system with deep hypersaline sedimentary basinal brines, and deep saline groundwaters in crystalline basement rocks, overlain by a shallow freshwater aquifer system. The site was glaciated several times during the Quaternary and may have been affected by recharge from glacial meltwater; • Dounreay, northeast Scotland: a deep (0-1400 m) groundwater flow system in fractured Precambrian crystalline basement overlain by fractured Devonian sedimentary rocks. This is within the coastal discharge area of a complex groundwater system, comprising deep saline groundwater hosted in crystalline basement, overlain by a fracture-controlled freshwater sedimentary aquifer system. Like Sellafield, this area experienced glaciation and may potentially record the impact of glacial meltwater recharge. In addition, a study has been made of two Quaternary sedimentary sequences in Andalusia in southeastern Spain to provide a basis of estimating the palaeoclimatic history of the region that could be used in any reconstruction of the palaeoclimatic history at the Los Ratones site: • The Cúllar-Baza lacustrine sequence records information about precipitation and palaeotemperature regimes, derived largely from the analysis of the stable isotope (δ18O and δ13C) signatures from biogenic calcite (ostracod shells). • The Padul Peat Bog sequence provided information on past vegetation cover and palaeogroundwater inputs based on the study of fossil pollen and biomarkers as proxies for past climate change. Following on from the earlier EC 4th Framework EQUIP project, the focus of the PADAMOT studies has been on calcite mineralization. Calcite has been identified as a late stage mineral, closely associated with hydraulically-conductive fractures in the present-day groundwater systems at the Äspö-Laxemar, Sellafield, Dounreay and Cloud Hill sites. At Los Ratones and Melechov sites late-stage mineralization is either absent or extremely scarce, and both the quantity and fine crystal size of any late-stage fracture mineralization relevant to Quaternary palaeohydrogeological investigations is difficult to work with. The results from the material investigated during the PADAMOT studies indicate that the fracture fillings at these sites are related to hydrothermal activity, and so do not have direct relevance as Quaternary indicators. Neoformed calcite has not been found at these two sites at the present depth of the investigations. Furthermore, the HCO3 - concentration in all the Los Ratones groundwaters is mainly controlled by complex carbonate dissolution. The carbonate mineral saturation indices do not indicate precipitation conditions, and this is consistent with the fact that neoformed calcite, ankerite or dolomite have not been observed petrographically

Kansen en bedreigingen voor mestvergisting en groengasproductie in de Gelderse landbouw : een eerste verkenning

Fermentation is a promising development in agriculture and beyond and anticipates to the desired availability of (locally produced) renewable sources of energy to replace fossil sources of energy

Quickscan opbrengsten en efficiëntie in de gangbare en biologische akkerbouw, melkveehouderij , varkenshouderij en pluimveehouderij : deelstudie van project ‘Duurzame Eiwitvoorziening’

De centrale onderzoeksvraag van onderhavige studie is als volgt geformuleerd: “Wat zijn de gemiddelde verschillen in gewasopbrengsten en in dierlijke productie (kg per ha per jaar) tussen gangbare en biologische landbouw, en waardoor worden deze verschillen veroorzaakt?” Het blijkt niet eenvoudig te zijn om een zuivere vergelijking te maken, omdat er verschillen zijn in soorten en – variëteiten, in bouwplannen en voorvruchten, in doelstellingen en in bedrijfssystemen tussen biologische en gangbare landbouw. Een vergelijking tussen opbrengsten en efficiëntie van biologische en gangbare landbouw kan daarom gekarakteriseerd worden als een vergelijking tussen appels en peren

Detection of Instrumental Drifts in the PEP II LER BPM System

During the last PEP-II run a major goal was to bring the Low-Energy Ring optics as close as possible to the design. A large number of BPMs exhibited sudden artificial jumps that interfered with this effort. The source of the majority of these jumps had been traced to the filter-isolator boxes (FIBs) near the BPM buttons. A systematic approach to find and repair the failing units had been developed and implemented. Despite this effort, the instrumental orbit jumps never completely disappeared. To trace the source of this behavior a test setup, using a spare Bergoz MX-BPM processor (kindly provided by SPEAR III at SSRL), was connected in parallel to various PEP-II BPM processors. In the course of these measurements a slow instrumental orbit drift was found which was clearly not induced by a moving positron beam. Based on the size of the system and the limited time before PEP-II closes in Oct.2008, an accelerator improvement project was initiated to install BERGOZ BPM-MX processors close to all sextupoles

De ammoniakemissie van de Nederlandse melkveehouderij bij een management gelijk aan dat van deelnemers aan "Koeien & Kansen"

De voor 2010 verwachte emissie van ammoniak vanuit de melkveehouderij wordt van 50 kton tot 40 kton teruggebracht als alle melkveehouders hun bedrijfsvoering verbeteren tot het huidige niveau van de 16 voorlopers in het project Koeien & Kansen. Beperking van de emissie is nodig voor het halen van de NEC-doelstellingen die de EU Nederland heeft opgelegd. De belangrijkste bijdrage aan die verbetering wordt geleverd door het beperken van eiwitovermaat in het rantsoen van het melkvee, waardoor de stikstofexcretie van de dieren lager wordt. Ook het beperken van het aantal stuks vee, door een hogere melkproductie per koe en niet meer jongvee aan te houden dan strikt nodig is om koeien te vervangen, werkt sterk door in de ammoniakverliezen. De stal blijft de belangrijkste ammoniakbron. Uit welzijnsoverwegingen neemt de ventilatie uit rundveestallen toe wat de ammoniakvervluchtiging bevordert. Aanbevolen wordt veehouders te helpen hun vakmanschap te verbeteren en de waardering voor goed vakmanschap tot uiting te laten komen in de wetgeving. Trefwoorden: ammoniak, melkveehouderij, milieu, Koeien & Kansen, NEC-richtlij

Inferring dynamic topology for decoding spatiotemporal structures in complex heterogeneous networks

Extracting complex interactions (i.e., dynamic topologies) has been an essential, but difficult, step toward understanding large, complex, and diverse systems including biological, financial, and electrical networks. However, reliable and efficient methods for the recovery or estimation of network topology remain a challenge due to the tremendous scale of emerging systems (e.g., brain and social networks) and the inherent nonlinearity within and between individual units. We develop a unified, data-driven approach to efficiently infer connections of networks (ICON). We apply ICON to determine topology of networks of oscillators with different periodicities, degree nodes, coupling functions, and time scales, arising in silico, and in electrochemistry, neuronal networks, and groups of mice. This method enables the formulation of these large-scale, nonlinear estimation problems as a linear inverse problem that can be solved using parallel computing. Working with data from networks, ICON is robust and versatile enough to reliably reveal full and partial resonance among fast chemical oscillators, coherent circadian rhythms among hundreds of cells, and functional connectivity mediating social synchronization of circadian rhythmicity among mice over weeks