151 research outputs found
What changes do we want to see at the next OWCs?
The Organic World Congress (OWC) will analyze the situation of the Organic world in 2014, discuss issues and develop strategies. Approaching our visions in a changing environment requires constant adjustments and actions. This applies equally to farmers, the value chain, consumption and the organic support sector. The OWC is an opportunity to reach shared conclusions on what actions and alliances with likeminded organizations (e.g. nature conversation or animal welfare NGOs) are needed so that the Organic World can grow and become more sustainable at the same time
Effective calculation of LEED intensities using symmetry-adapted functions
The calculation of LEED intensities in a spherical-wave representation can be substantially simplified by symmetry relations. The wave field around each atom is expanded in symmetry-adapted functions where the local point symmetry of the atomic site applies. For overlayer systems with more than one atom per unit cell symmetry-adapted functions can be used when the division of the crystal into monoatomic subplanes is replaced by division into subplanes containing all symmetrically equivalent atomic positions
First evidence of established populations of the taiga tick Ixodes persulcatus (Acari: Ixodidae) in Sweden
Background: The tick species Ixodes ricinus and I. persulcatus are of exceptional medical importance in the western and eastern parts, respectively, of the Palaearctic region. In Russia and Finland the range of I. persulcatus has recently increased. In Finland the first records of I. persulcatus are from 2004. The apparent expansion of its range in Finland prompted us to investigate if I. persulcatus also occurs in Sweden. Methods: Dog owners and hunters in the coastal areas of northern Sweden provided information about localities where ticks could be present. In May-August 2015 we used the cloth-dragging method in 36 localities potentially harbouring ticks in the Bothnian Bay area, province Norrbotten (NB) of northern Sweden. Further to the south in the provinces Vasterbotten (VB) and Uppland (UP) eight localities were similarly investigated. Results: Ixodes persulcatus was detected in 9 of 36 field localities in the Bothnian Bay area. Nymphs, adult males and adult females (n = 46 ticks) of I. persulcatus were present mainly in Alnus incana - Sorbus aucuparia - Picea abies - Pinus sylvestris vegetation communities on islands in the Bothnian Bay. Some of these I. persulcatus populations seem to be the most northerly populations so far recorded of this species. Dog owners asserted that their dogs became tick-infested on these islands for the first time 7-8 years ago. Moose (Alces alces), hares (Lepus timidus), domestic dogs (Canis lupus familiaris) and ground-feeding birds are the most likely carriers dispersing I. persulcatus in this area. All ticks (n = 124) from the more southern provinces of VB and UP were identified as I. ricinus. Conclusions: The geographical range of the taiga tick has recently expanded into northern Sweden. Increased information about prophylactic, anti-tick measures should be directed to people living in or visiting the coastal areas and islands of the Baltic Bay.Peer reviewe
Manifestations of Broken Symmetry: The Surface Phases of Ca(2-x)Sr(x)RuO4
The surface structural phases of Ca(2-x)Sr(x)RuO(4) are investigated using
quantitative Low Energy Electron Diffraction. The broken symmetry at the
surface enhances the structural instability against the RuO6 rotational
distortion while diminishing the instability against the RuO6 tilt distortion
occurring within the bulk crystal. As a result, suppressed structural and
electronic surface phase transition temperatures are observed, including the
appearance of an inherent Mott metal-to-insulator transition for x = 0.1 and
possible modifications of the surface quantum critical point near xc ~ 0.5.Comment: 4 pages, 4 figure
Dynamic image potential at an Al(111) surface
We evaluate the electronic self-energy Sigma(E) at an Al(111) surface using the GW space-time method. This self-energy automatically includes the image potential V-im not present in any local-density approximation for exchange and correlation. We solve the energy-dependent quasiparticle equations and calculate the effective local potential experienced by electrons in the near-surface region. The relative contribution of exchange proves to be very different for states above the Fermi level. The image-plane position for interacting electrons is closer to the surface than for the purely electrostatic effects felt by test charges, and, like its classical counterpart, is drawn inwards by the effects of atomic structure
Bias-voltage dependence of the magneto-resistance in ballistic vacuum tunneling: Theory and application to planar Co(0001) junctions
Motivated by first-principles results for jellium and by surface-barrier
shapes that are typically used in electron spectroscopies, the bias voltage in
ballistic vacuum tunneling is treated in a heuristic manner. The presented
approach leads in particular to a parameterization of the tunnel-barrier shape,
while retaining a first-principles description of the electrodes. The proposed
tunnel barriers are applied to Co(0001) planar tunnel junctions. Besides
discussing main aspects of the present scheme, we focus in particular on the
absence of the zero-bias anomaly in vacuum tunneling.Comment: 19 pages with 8 figure
Steam reforming on transition-metal carbides from density-functional theory
A screening study of the steam reforming reaction (CH_4 + H_2O -> CO + 3H_2)
on early transition-metal carbides (TMC's) is performed by means of
density-functional theory calculations. The set of considered surfaces includes
the alpha-Mo_2C(100) surfaces, the low-index (111) and (100) surfaces of TiC,
VC, and delta-MoC, and the oxygenated alpha-Mo_2C(100) and TMC(111) surfaces.
It is found that carbides provide a wide spectrum of reactivities towards the
steam reforming reaction, from too reactive via suitable to too inert. The
reactivity is discussed in terms of the electronic structure of the clean
surfaces. Two surfaces, the delta-MoC(100) and the oxygen passivated
alpha-Mo_2C(100) surfaces, are identified as promising steam reforming
catalysts. These findings suggest that carbides provide a playground for
reactivity tuning, comparable to the one for pure metals.Comment: 6 pages, 4 figure
Low-energy electron diffraction analysis of the structure of a Cs-O/Ru(0001) coadsorbate phase
The structure of the (â3 Ă â3 )R30° overlayer formed by coadsorption of Cs and O atoms (ΞCs=Ξ0=0.33) on a Ru(0001) surface was determined by low-energy electron diffraction. Both adsorbates occupy hcp-type hollow sites. If compared with the structures of the respective pure adsorbate phases, the bond lengths are modified in a way consistent with an effective transfer of electronic charge from Cs to O
Quantitative versus standard pupillary light reflex for early prognostication in comatose cardiac arrest patients: an international prospective multicenter double-blinded study.
To assess the ability of quantitative pupillometry [using the Neurological Pupil index (NPi)] to predict an unfavorable neurological outcome after cardiac arrest (CA).
We performed a prospective international multicenter study (10 centers) in adult comatose CA patients. Quantitative NPi and standard manual pupillary light reflex (sPLR)-blinded to clinicians and outcome assessors-were recorded in parallel from day 1 to 3 after CA. Primary study endpoint was to compare the value of NPi versus sPLR to predict 3-month Cerebral Performance Category (CPC), dichotomized as favorable (CPC 1-2: full recovery or moderate disability) versus unfavorable outcome (CPC 3-5: severe disability, vegetative state, or death).
At any time between day 1 and 3, an NPiââ€â2 (nâ=â456 patients) had a 51% (95% CI 49-53) negative predictive value and a 100% positive predictive value [PPV; 0% (0-2) false-positive rate], with a 100% (98-100) specificity and 32% (27-38) sensitivity for the prediction of unfavorable outcome. Compared with NPi, sPLR had significantly lower PPV and significantly lower specificity (pâ <â0.001 at day 1 and 2; p â=â0.06 at day 3). The combination of NPiââ€â2 with bilaterally absent somatosensory evoked potentials (SSEP; nâ=â188 patients) provided higher sensitivity [58% (49-67) vs. 48% (39-57) for SSEP alone], with comparable specificity [100% (94-100)].
Quantitative NPi had excellent ability to predict an unfavorable outcome from day 1 after CA, with no false positives, and significantly higher specificity than standard manual pupillary examination. The addition of NPi to SSEP increased sensitivity of outcome prediction, while maintaining 100% specificity
Science and society in education
This booklet is for teachers who want to expand their
teaching approaches to include socio-scientific issues
which enrich and give meaning to core scientific principles.
It is meant to enhance young peopleâs curiosity about the
social and scientific world and raise important questions
about issues which affect their lives. We call this approach
Socio-Scientific Inquiry-Based Learning, or âSSIBLâ for
short. Chapters 1 and 2 present an introduction to the
theoretical background of SSIBL. In chapter 3, SSIBL will
be approached from a classroom perspective, providing a
simplified version of the framework and showing teaching
examples
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