Electric field control of spin lifetimes in Nb-SrTiO3_3 by spin-orbit fields

We show electric field control of the spin accumulation at the interface of the oxide semiconductor Nb-SrTiO$_{3}$ with Co/AlO$_{x}$ spin injection contacts at room temperature. The in-plane spin lifetime $\tau_\parallel$ as well as the ratio of the out-of-plane to in-plane spin lifetime $\tau_\perp/\tau_\parallel$ is manipulated by the built-in electric field at the semiconductor surface, without any additional gate contact. The origin of this manipulation is attributed to Rashba Spin-Orbit Fields (SOFs) at the Nb-SrTiO$_3$ surface and shown to be consistent with theoretical model calculations based on SOF spin flip scattering. Additionally, the junction can be set in a high or low resistance state, leading to a non-volatile control of $\tau_\perp/\tau_\parallel$, consistent with the manipulation of the Rashba SOF strength. Such room temperature electric field control over the spin state is essential for developing energy-efficient spintronic devices and shows promise for complex oxide based (spin)electronicsComment: 5 pages, 4 figure

Merger Performance and Efficiencies in Horizontal Merger Policy in the US and the EU

In current horizontal merger policy in the US and the EU an explicit efficiency defense is allowed. On both sides of the Atlantic mergers are unconditionally approved if internal efficiencies are sufficient to reverse the mergers’ potential to harm consumers in the relevant market. Current merger policy is implicitly based on the assumption that rational managers will only propose privately profitable mergers. In this thesis I will show that the empirical evidence on merger performance suggests that this assumption can’t be sustained. Managers do propose uneconomic mergers, motivated by non-wealth maximizing behavior. To tackle this problem I argue that efficiencies should not only be used as an efficiency defense, but efficiencies should work both ways. To avoid type I and type II errors the competition authorities in the US and the EU should undertake a sequential efficiency test in their assessment of specific mergers.Merger; competition policy; efficiencies; efficiency defence; merger performance; rational manager

Noradrenergic and dopaminergic therapy in Parkinson's disease:preclinical studies on L-threo-DOPS, decarboxylase inhibitors and transdermal lisuride

Bij de palliatieve behandeling van de ziekte van Parkinson (PD) blijken nog veel symptomen niet op de gebruikelijke therapie met dopamine (DA) suppleterende of dopaminomimetische farmaka te reageren. De studies bijeen gebracht in dit proefschrift beschrijven twee alternatieve benaderingen in de farmacotherapeutische behandeliig van PD: versterking van de noradrenerge neurotransrnissie met behulp van een precursor van noradrenaline (NA), en het ontwikkelen van een eenvoudig transdermaal toedieningssysteem voor de dopamine agonist lisuride. De niet op dopaminerge therapie reagerende motorische en niet-motorische (autonome, cognitieve) symptomen worden meer en meer toegeschreven aan een eveneens minder functionele noradrenerge neurotransmissie in de hersenen van parkinson patiënten. Het proefschrift beschrijft experimenten in proefdieren welke tot doel hadden het intracerebrale werkingsmechanisme van L-threo-DOPS (DOPS), de precursor van noradrenaline (NA) op te helderen. DOPS is succesvol toegepast bij de behandeling van freezing en akinesie bij japanse parkinson patienten. De standaard therapie bij PD met levodopa (DOPA) in een combinatiepreparaat met een perifere decarboxylase remmer (DCI) werd geëvalueerd op eventuele werkzaamheid van de DCI in het centrale zenuwstelsel (CZS). Het grote verschil in plasma halfwaardetijd van DOPA en de DCI kan mogelijk een rol spelen bij de verminderde werkzaamheid van de DOPAIDCI combinatiepreparaten (Sinemet, Madopar) na 4 à 5 jaar continu gebruik. Eventuele activiteit van de DCI in het CZS zou bovendien eveneens de werkzaamheid van DOPS in het CZS nadelig beinvloeden. De studies werden uitgevoerd in de rat, en bij patienten bij wie ondanks hoge doses DOPAIDCI geen bevredigende klinische respons bereikt kon worden. Tenslotte is gepoogd een transdermaal toedieningssysteem te ontwikkelen voor de dopamine agonist lisuride. Door de continue afgifte via de huid kunnen wellicht fluctuaties in de plasmaspiegel van lisuride en de daaraan gerelateerde grillige klinische respons en bijwerkingen voorkomen worden

Identification of a Baeyer-Villiger monooxygenase sequence motif

Baeyer-Villiger monooxygenases (BVMOs) form a distinct class of flavoproteins that catalyze the insertion of an oxygen atom in a C-C bond using dioxygen and NAD(P)H. Using newly characterized BVMO sequences, we have uncovered a BVMO-identifying sequence motif: FXGXXXRXXXW(P/D). Studies with site-directed mutants of 4-hydroxyacetophenone monooxygenase from Pseudomonas fluorescens ACB suggest that this fingerprint sequence is critically involved in catalysis. Further sequence analysis showed that the BVMOs belong to a novel superfamily that comprises three known classes of FAD-dependent monooxygenases: the so-called flavin-containing monooxygenases (FMOs), the N-hydroxylating monooxygenases (NMOs), and the BVMOs. Interestingly, FMOs contain an almost identical sequence motif when compared to the BVMO sequences: FXGXXXHXXX(Y/F). Using these novel amino acid sequence fingerprints, BVMOs and FMOs can be readily identified in the protein sequence databank. (C) 2002 Federation of European Biochemical Societies. Published by Elsevier Science B.V. All rights reserved

Large room-temperature tunneling anisotropic magnetoresistance and electroresistance in single ferromagnet/Nb:SrTiO3 Schottky devices

Abstract There is a large effort in research and development to realize electronic devices capable of storing information in new ways - for instance devices which simultaneously exhibit electro and magnetoresistance. However it remains a challenge to create devices in which both effects coexist. In this work we show that the well-known electroresistance in noble metal-Nb:SrTiO3 Schottky junctions can be augmented by a magnetoresistance effect in the same junction. This is realized by replacing the noble metal electrode with ferromagnetic Co. This magnetoresistance manifests as a room temperature tunneling anisotropic magnetoresistance (TAMR). The maximum room temperature TAMR (1.6%) is significantly larger and robuster with bias than observed earlier, not using Nb:SrTiO3. In a different set of devices, a thin amorphous AlOx interlayer inserted between Co and Nb:SrTiO3, reduces the TAMR by more than 2 orders of magnitude. This points to the importance of intimate contact between the Co and Nb:SrTiO3 for the TAMR effect. This is explained by electric field enhanced spin-orbit coupling of the interfacial Co layer in contact with Nb:SrTiO3. We propose that the large TAMR likely has its origin in the 3d orbital derived conduction band and large relative permittivity of Nb:SrTiO3 and discuss ways to further enhance the TAMR