Angaben zur Klimarelevanz als Bewertungsgrundlage für unterschiedliche landwirtschaftliche Produktionsverfahren und Nachfrageorientierungen

Zusammenfassung: Das Konzept der Klimarelevanz wird vorgestellt und auf die Analyse der Sektoren Landwirtschaft und Ernährung angewendet. Einige Ergebnisse werden gezeigt, die u.a. die systematische Unterschätzung von Anteilen der Landwirtschaft an der Klimabeeinflussung belegen. Es wird auch gezeigt, wie mit der Inblicknahme des Gesamtsystems der Aspekt der Landnutzung einbezogen werden kann und wie Veränderungen in den Versorgungssystemen sich dort bemerkbar machen

THE DETERMINATION OF TRACE METALS BY CAPILLARY ELECTROPHORESIS

The development of a capillary electrophoresis (CE) method for the determination of inorganic and organo mercury species as their dithizone sulphonate (DzS) complexes using coated capillary columns is described. The complexes were pre-formed before injection and detection was by direct measurement of the visible absorbance of the complexes. Dithizone sulphonate was used in place of cysteine to separate methyl mercury in the final stage of a simplified Westoo extraction procedure. The method was than applied to the analysis of methyl mercury in a crab and several fish meat samples. Good quantitative performance is demonstrated by spiking experiments and analysis of DORM-1 certified reference material. The method was found to be very sensitive and a detection limit of 2 µg Kgˉ¹ could be achieved for a l0g sample of fish flesh. A CE method for the determination of uranium (VI) as the arsenazo III complex was developed and the effect of interfering metal ions was studied. The calibration was found to be linear from 10 µg 1ˉ¹ -10 mg 1ˉ¹ using gravity injections and a detection limit of less than 1 µg 1ˉ¹ was achieved with electrokinetic injection. A study was made of injection techniques and their applicability to the enhancement of sensitivity in synthetic standards and environmental samples. The effect of capillary surface chemistry on the peak shape of the migrating uranyl-arsenazo III was also studied using fused silica capillaries with two different internal coatings and three polymeric capillaries. A study was also carried out on the construction and investigation of a post-capillary reactor for the determination of trace metals by UV-Vis absorption after formation of intensely absorbing coloured complexes. The main principle of operation was based on the infusion of the colorimetric reagent into a small 50µm gap between the separation capillary and the reaction capillary. The gap was enclosed by a permeable membrane and the flow of reagent was achieved by the application of a slight pressure to the post-capillary reactor cell. Two reagents were studied, namely, xylenol orange (XO) and 4 (2-pyridylazo) resorcinol (PAR), for the separation and detection of copper (U), cadmium (II), cobalt (II), nickel (II), zinc (II), and manganese (II). Lead (II) was also included in the XO system.Dionex, U

Impact of the various spin and orbital ordering processes on multiferroic properties of orthovanadate DyVO3

The orthovanadate DyVO3 crystal, known to exhibit multiple structural, spin and orbital ordering transitions, is presently investigated on the basis of magnetization, heat capacity, resistivity, dielectric and polarization measurements. Our main result is experimental evidence for the existence of multiferroicity below a high TC of 108 K over a wide temperature range including different spin-orbital ordered states. The onset of ferroelectricity is found to coincide with the antiferromagnetic C-type spin ordering transition taking place at 108 K, which indicates that DyVO3 belongs to type II multiferroics exhibiting a coupling between magnetism and ferroelectricity. Some anomalies detected on the temperature dependence of electric polarization are discussed with respect to the nature of the spin-orbital ordered states of the V sublattice and the degree of spin alignment in the Dy sublattice. The orthovanadates RVO3 (R = rare earth or Y) form an important new category for searching for high-TC multiferroics.Comment: 25 pages, 7 figures, 68 references, one supplementary material, Physical Review B, Published 23 July 201

Taking the lead: learners’ experiences across the disciplines

The first year at university is a time of significant flux for students, as they adjust to unfamiliar environments, encounter new approaches to teaching and develop fresh learning strategies on the road to becoming self-directed learners. This sense of uncertainty may be compounded by the need to interact with unfamiliar and frequently complex online systems and technologies, possibly even before arrival. Furthermore, although technology is embedded seamlessly into the personal lives of many of today’s students, recent reports have questioned the widespread assumption that young adults have the sophisticated information skills and digital literacy needed to become autonomous learners. In this paper we present findings from a recently-completed study addressing these important issues. We investigated the utilisation of ICT and learning technologies by first-year undergraduates from a variety of different entry routes and academic disciplines, including Physics, Divinity and Veterinary Medicine, at the University of Edinburgh. The focus of the work was on the impact of technology on students’ transition to university and how this changed as they progressed through their first year. The overall shape of the research was based on a student-centred approach, with students’ own views and opinions placed central to the study; and used a holistic approach in which students’ use of e-learning and technology was set within the context of their learning experiences as a whole. To capture the breadth and complexity of their experiences we used a mixed-mode approach, including a series of reflective diaries recorded by learners (in video, audio or text format) together with surveys and focus groups. Students do not form a homogenous group, and findings in this area are inevitably complex. They have high expectations and are generally confident with technology; however, they may not always recognise technology’s potential to support and enhance learning. The term e-learning does not mean much to them; there is simply learning with strands of technology running through. This is reflected in a strong desire for face-to-face contact, with technology used to supplement and enhance this. Students are social, with informal group learning often facilitated by technology. They find their comfort zones and ways of working that are personal to them, and use technology to suit their own way of learning

Field dependence of the electronic phase separation in Pr0.67Ca0.33MnO3 by small angle magnetic neutron scattering

We have studied by small angle neutron scattering the evolution induced by the application of magnetic field of the coexistence of ferromagnetism (F) and antiferromagnetism (AF) in a crystal of Pr$_{0.67}$Ca$_{0.33}$MnO$_3$. The results are compared to magnetic measurements which provide the evolution of the ferromagnetic fraction. These results show that the growth of the ferromagnetic phase corresponds to an increase of the thickness of the ferromagnetic ''cabbage'' sheets

Concavity of Eigenvalue Sums and the Spectral Shift Function

It is well known that the sum of negative (positive) eigenvalues of some finite Hermitian matrix $V$ is concave (convex) with respect to $V$. Using the theory of the spectral shift function we generalize this property to self-adjoint operators on a separable Hilbert space with an arbitrary spectrum. More precisely, we prove that the spectral shift function integrated with respect to the spectral parameter from $-\infty$ to $\lambda$ (from $\lambda$ to $+\infty$) is concave (convex) with respect to trace class perturbations. The case of relative trace class perturbations is also considered