Möglichkeiten des Praxistransfers anhand des Projektes „Umstellung zur ökologischen Milchviehhaltung“

Für konventionelle Betriebe stellen die Fragen der Vermarktung, der Wirtschaftlichkeit sowie der Arbeitsbelastung die größten Hürden bei einer Umstellung hin zu einer ökologi-schen Wirtschaftsweise dar. Diese Fragen muss die Beratung vordringlich beantworten. Bereits umgestellte Betriebe haben einen guten Zufriedenheitsgrad (75% sind mit der Um-stellung zufrieden). Dies liegt vor allem an der subjektiv wahrgenommenen Verbesserung der Wirtschaftlichkeit. Offene Fragen bestehen im Bereich der „Bürokratie“ und der Regulierung von Ampfer (Rumex obtusifolius). Der ökologische Zuchtwert ÖZW ist in der praktischen Zucht noch noch viel zu wenig verankert und bekannt. Hier muss gezielte Beratung den guten theoretischen Ansatz des ÖZW den Landwirten vermitteln. Öko Betriebe haben etwa 92-95% der Grünlanderträge konventioneller Betriebe. Die Be-ratung unterstützt daher Umstellungsbetriebe bei der Suche nach potentiellen Pachtflä-chen, Almen und Aufzuchtbetrieben für auszulagerndes Jungvieh. Die Eiweißgehalte im Gras sind bei Öko Betrieben niedriger, alle anderen Faktoren sind etwa gleich. Dies ist bei der Rationsgestaltung zu berücksichtigen. Bei der Düngung ist vor allem auf eine ausrei-chende Phosphat Versorgung zu achten. Nur etwa 30% der Landwirte erzielen ein positives kalkulatorisches Betriebsergebnis, unabhängig vom Haltungssystem. Die Unterschiede zwischen den Betriebsergebnissen sind vor allem auf die Managementfähigkeiten der Betriebsleiter und die Reinvestitionen erzielter Gewinne zurück zu führen. Die Wirtschaftlichkeit ist bei Bio Betrieben mit ca. 3 Cent Gewinn je Liter Milch besser. Hierbei ist zu berücksichtigen dass auch mehrheitlich solche Betriebe umgestellt haben die für das System gute Voraussetzungen mitbringen. Seit der Untersuchung hat sich das Preisverhältnis von Bio-Milch zu konventionell erzeugter Milch vergrößert. Die Gewinnunterschiede je Liter Milch haben sich weiter zu Gunsten der Öko Betriebe verschoben. Der umfassende Literaturteil der vorliegenden Untersuchung bietet gerade jungen Beratern eine schnelle Orientierung über den Stand der Forschung zur ökologischen Milchviehhaltung

Disentangling magnetic hardening and molecular spin chain contributions to exchange bias in ferromagnet/molecule bilayers

We performed SQUID and FMR magnetometry experiments to clarify the relationship between two reported magnetic exchange effects arising from interfacial spin-polarized charge transfer within ferromagnetic metal (FM)/molecule bilayers: the magnetic hardening effect, and spinterface-stabilized molecular spin chains. To disentangle these effects, both of which can affect the FM magnetization reversal, we tuned the metal phthalocyanine molecule central site's magnetic moment to selectively enhance or suppress the formation of spin chains within the molecular film. We find that both effects are distinct, and additive. In the process, we 1) extended the list of FM/molecule candidate pairs that are known to generate magnetic exchange effects, 2) experimentally confirmed the predicted increase in anisotropy upon molecular adsorption; and 3) showed that spin chains within the molecular film can enhance magnetic exchange. This magnetic ordering within the organic layer implies a structural ordering. Thus, by distengangling the magnetic hardening and exchange bias contributions, our results confirm, as an echo to progress regarding inorganic spintronic tunnelling, that the milestone of spintronic tunnelling across structurally ordered organic barriers has been reached through previous magnetotransport experiments. This paves the way for solid-state devices studies that exploit the quantum physical properties of spin chains, notably through external stimuli.Comment: Non

Switching of magnetization by non-linear resonance studied in single nanoparticles

Magnetization reversal in magnetic particles is one of the fundamental issues in magnetic data storage. Technological improvements require the understanding of dynamical magnetization reversal processes at nanosecond time scales. New strategies are needed to overcome current limitations. For example, the problem of thermal stability of the magnetization state (superparamagnetic limit) can be pushed down to smaller particle sizes by increasing the magnetic anisotropy. High fields are then needed to reverse the magnetization that are difficult to achieve in current devices. Here we propose a new method to overcome this limitation. A constant applied field, well below the switching field, combined with a radio-frequency (RF) field pulse can reverse the magnetization of a nanoparticle. The efficiency of this method is demonstrated on a 20 nm cobalt particle by using the micro-SQUID technique. Other applications of this method might be nucleation or depinning of domain walls.Comment: 11 pages, 5 figure

The relentless variability of Mrk 421 from the TeV to the radio

The origin of the gamma-ray emission of the blazar Mrk 421 is still a matter of debate. We used 5.5 years of unbiased observing campaign data, obtained using the FACT telescope and the Fermi LAT detector at TeV and GeV energies, the longest and densest so far, together with contemporaneous multi-wavelength observations, to characterise the variability of Mrk 421 and to constrain the underlying physical mechanisms. We studied and correlated light curves obtained by ten different instruments and found two significant results. The TeV and X-ray light curves are very well correlated with a lag of <0.6 days. The GeV and radio (15 Ghz band) light curves are widely and strongly correlated. Variations of the GeV light curve lead those in the radio. Lepto-hadronic and purely hadronic models in the frame of shock acceleration predict proton acceleration or cooling timescales that are ruled out by the short variability timescales and delays observed in Mrk 421. Instead the observations match the predictions of leptonic models.Comment: 10 pages, 8 figures, 1 tabl

Mitochondrial DNA haplogroup T is associated with coronary artery disease and diabetic retinopathy: a case control study

<p>Abstract</p> <p>Background</p> <p>There is strong and consistent evidence that oxidative stress is crucially involved in the development of atherosclerotic vascular disease. Overproduction of reactive oxygen species (ROS) in mitochondria is an unifying mechanism that underlies micro- and macrovascular atherosclerotic disease. Given the central role of mitochondria in energy and ROS production, mitochondrial DNA (mtDNA) is an obvious candidate for genetic susceptibility studies on atherosclerotic processes. We therefore examined the association between mtDNA haplogroups and coronary artery disease (CAD) as well as diabetic retinopathy.</p> <p>Methods</p> <p>This study of Middle European Caucasians included patients with angiographically documented CAD (n = 487), subjects with type 2 diabetes mellitus with (n = 149) or without (n = 78) diabetic retinopathy and control subjects without clinical manifestations of atherosclerotic disease (n = 1527). MtDNA haplotyping was performed using multiplex PCR and subsequent multiplex primer extension analysis for determination of the major European haplogroups. Haplogroup frequencies of patients were compared to those of control subjects without clinical manifestations of atherosclerotic disease.</p> <p>Results</p> <p>Haplogroup T was significantly more prevalent among patients with CAD than among control subjects (14.8% vs 8.3%; p = 0.002). In patients with type 2 diabetes, the presence of diabetic retinopathy was also significantly associated with a higher prevalence of haplogroup T (12.1% vs 5.1%; p = 0.046).</p> <p>Conclusion</p> <p>Our data indicate that the mtDNA haplogroup T is associated with CAD and diabetic retinopathy in Middle European Caucasian populations.</p