Coherent control of a nanomechanical two-level system

The Bloch sphere is a generic picture describing a coupled two-level system and the coherent dynamics of its superposition states under control of electromagnetic fields. It is commonly employed to visualise a broad variety of phenomena ranging from spin ensembles and atoms to quantum dots and superconducting circuits. The underlying Bloch equations describe the state evolution of the two-level system and allow characterising both energy and phase relaxation processes in a simple yet powerful manner. Here we demonstrate the realisation of a nanomechanical two-level system which is driven by radio frequency signals. It allows to extend the above Bloch sphere formalism to nanoelectromechanical systems. Our realisation is based on the two orthogonal fundamental flexural modes of a high quality factor nanostring resonator which are strongly coupled by a dielectric gradient field. Full Bloch sphere control is demonstrated via Rabi, Ramsey and Hahn echo experiments. This allows manipulating the classical superposition state of the coupled modes in amplitude and phase and enables deep insight into the decoherence mechanisms of nanomechanical systems. We have determined the energy relaxation time T1 and phase relaxation times T2 and T2*, and find them all to be equal. This not only indicates that energy relaxation is the dominating source of decoherence, but also demonstrates that reversible dephasing processes are negligible in such collective mechanical modes. We thus conclude that not only T1 but also T2 can be increased by engineering larger mechanical quality factors. After a series of ground-breaking experiments on ground state cooling and non-classical signatures of nanomechanical resonators in recent years, this is of particular interest in the context of quantum information processing

Signatures of two-level defects in the temperature-dependent damping of nanomechanical silicon nitride resonators

The damping rates of high quality factor nanomechanical resonators are well beyond intrinsic limits. Here, we explore the underlying microscopic loss mechanisms by investigating the temperature-dependent damping of the fundamental and third harmonic transverse flexural mode of a doubly clamped silicon nitride string. It exhibits characteristic maxima reminiscent of two-level defects typical for amorphous materials. Coupling to those defects relaxes the momentum selection rules, allowing energy transfer from discrete long wavelength resonator modes to the high frequency phonon environment

Feministische Musikpädagogik - sektiererischer Irrweg oder Chance zu einer Neuorientierung?

In der Neuen Musikzeitung wurde abschätzig bemerkt, "Frauen- oder Friedensthemen" seien in der Musikpädagogik passe. Sicherlich kann man sich je nach politischer Couleur über Sinn und Nutzen einer Friedenserziehung im Musikunterricht streiten. Aber kann man "Frauenthemen" als Modeerscheinung abtun? Es scheint, als ginge der große Umorientierungsprozeß, der in Bezug auf Frauenforschung in anderen Disziplinen längst Fuß gefaßt und zu einer Verunsicherung etablierter Wissenschaft geführt hat, an der Musikpädagogik spurlos vorüber. In diesem Beitrag wird die These aufgestellt und ausgeführt, daß es sich bei einem feministischen Forschungsansatz um eine gesellschaftlich überfällige und notwendige Neuorientierung handelt, die nicht einer Randgruppe zugewiesen werden, sondern von der traditionellen Forschung rezipiert und weiter vorangetragen werden sollte. (DIPF/Orig.

Non-adiabatic dynamics of two strongly coupled nanomechanical resonator modes

The Landau-Zener transition is a fundamental concept for dynamical quantum systems and has been studied in numerous fields of physics. Here we present a classical mechanical model system exhibiting analogous behaviour using two inversely tuneable, strongly coupled modes of the same nanomechanical beam resonator. In the adiabatic limit, the anticrossing between the two modes is observed and the coupling strength extracted. Sweeping an initialized mode across the coupling region allows mapping of the progression from diabatic to adiabatic transitions as a function of the sweep rate

Frauen- und Männerbilder in der Musik: Festschrift für Eva Rieger zum 60. Geburtstag

Wie haben sich unterschiedliche Frauen- und Männerbilder in die Musikgeschichte eingeschrieben? Wie haben unterschiedliche Lebenserfahrungen und Verhaltensnormen der Geschlechter musikalische Kultur geprägt - in Kompositionen, in Biographien, in der Rezeption, in der Inszenierung und Vermittlung von Musik? 20 Autorinnen aus Deutschland, Österreich und den USA gehen diesen Fragen nach und vermitteln damit einen facettenreichen Einblick in den gegenwärtigen Stand der musikwissenschaftlichen Frauen- und Geschlechterforschun

Energy losses of nanomechanical resonators induced by atomic force microscopy- controlled mechanical impedance mismatching

Clamping losses are a widely discussed damping mechanism in nanoelectromechanical systems, limiting the performance of these devices. Here we present a method to investigate this dissipation channel. Using an atomic force microscope tip as a local perturbation in the clamping region of a nanoelectromechanical resonator, we increase the energy loss of its flexural modes by at least one order of magnitude. We explain this by a transfer of vibrational energy into the cantilever, which is theoretically described by a reduced mechanical impedance mismatch between the resonator and its environment. A theoretical model for this mismatch, in conjunction with finite element simulations of the evanescent strain field of the mechanical modes in the clamping region, allows us to quantitatively analyse data on position and force dependence of the tip-induced damping. Our experiments yield insights into the damping of nanoelectromechanical systems with the prospect of engineering the energy exchange in resonator networks

Frequency and Q-factor control of nanomechanical resonators

We present an integrated scheme for dielectric drive and read-out of high-Q nanomechanical resonators which enables tuning of both the resonance frequency and quality factor with an applied DC voltage. A simple model for altering these quantities is derived, incorporating the resonator's complex electric polarizability and position in an inhomogeneous electric field, which agrees very well with the experimental findings as well as FEM simulations. By comparing two sample geometries we are able to show that careful electrode design can determine the direction of frequency tuning of flexural in- and out-of-plane modes of a string resonator. Furthermore we demonstrate that the mechanical quality factor can be voltage reduced more than fivefold

THE OUTCOME OF PSYCHIATRIC REHABILITATION TREATMENT DEPENDS ON AFFECTIVE STATE AT THE TIME OF ADMISSION

Background: In Austria, new approaches of rehabilitation programs focus on the prevention of mental illness and offer treatment not only for acute psychiatric patients, but also for those who are at risk of developing a mental disorder or have recovered from one.The aim of this study was to determine the effects of a psychiatric rehabilitation program on individuals with different mood states. Subjects and methods: 600 patients with a history of affective disorder were tested at the time of admission to an Austrian inpatient psychiatric rehabilitation center. Data of extreme groups - patients who were depressed (n=59; BDI-II <9 and HAMD <8) or euthymic (n=59; BDI 19) at the time of therapy start - were analyzed. The participants completed the Maslach Burnout Inventory - General Survey, the Symptom Checklist - Revised and the Stress Coping Questionnaire at the beginning and the end of the 6-weeks rehabilitation program. Results: After 6 weeks, both groups showed significantly less psychiatric symptoms (BDI-II, HAMD, SCL-90, and negative coping strategies (SVF). Importantly, work-related stress symptoms (“burnout” symptoms) improved significantly in the euthymic group. Conclusions: Euthymic patients seem to be able to focus on work-related stress symptoms including reduced emotional exhaustion through treatment, while currently depressed patients primarily benefit by an improvement in general psychiatric symptomatology. The results indicate the crucial role of mood state validated with standardized psychological questionnaires BDI-II and HAMD at time of admission to such programs. These findings could have implications on treatment decisions for psychiatric patients and assist in making a forecast concerning ability to recover and treatment prognosis

LUBAC assembles a ubiquitin signaling platform at mitochondria for signal amplification and transport of NF-κB to the nucleus

Mitochondria are increasingly recognized as cellular hubs to orchestrate signaling pathways that regulate metabolism, redox homeostasis, and cell fate decisions. Recent research revealed a role of mitochondria also in innate immune signaling; however, the mechanisms of how mitochondria affect signal transduction are poorly understood. Here, we show that the NF-κB pathway activated by TNF employs mitochondria as a platform for signal amplification and shuttling of activated NF-κB to the nucleus. TNF treatment induces the recruitment of HOIP, the catalytic component of the linear ubiquitin chain assembly complex (LUBAC), and its substrate NEMO to the outer mitochondrial membrane, where M1- and K63-linked ubiquitin chains are generated. NF-κB is locally activated and transported to the nucleus by mitochondria, leading to an increase in mitochondria-nucleus contact sites in a HOIP-dependent manner. Notably, TNF-induced stabilization of the mitochondrial kinase PINK1 furthermore contributes to signal amplification by antagonizing the M1-ubiquitin-specific deubiquitinase OTULIN. Overall, our study reveals a role for mitochondria in amplifying TNF-mediated NF-κB activation, both serving as a signaling platform, as well as a transport mode for activated NF-κB to the nuclear

Navigating the Future of Organisational Health Services Research in Germany and beyond:a Position Paper

Background Recent analyses have shown that in health services research in Germany, healthcare organisations are often considered primarily as a study setting, without fully taking their complex organisational nature into account, neither theoretically nor methodologically. Therefore, an initiative was launched to analyse the state of Organisational Health Services Research (OHSR) in Germany and to develop a strategic framework and road map to guide future efforts in the field. This paper summarizes positions that have been jointly developed by consulting experts from the interdisciplinary and international scientific community.Methods In July 2023, a scoping workshop over the course of three days was held with 32 (inter)national experts from different research fields centred around OHSR topics using interactive workshop methods. Participants discussed their perspectives on OHSR, analysed current challenges in OHSR in Germany and developed key positions for the field’s development.Results The seven agreed-upon key positions addressed conceptual and strategic aspects. There was consensus that the field required the development of a research agenda that can guide future efforts. On a conceptual level, the need to address challenges in terms of interdisciplinarity, terminology, organisation(s) as research subjects, international comparative research and utilisation of organisational theory was recognized. On a strategic level, requirements with regard to teaching, promotion of interdisciplinary and international collaboration, suitable funding opportunities and participatory research were identified.Conclusions This position paper seeks to serve as a framework to support further development of OHSR in Germany and as a guide for researchers and funding organisations on how to move OHSR forward. Some of the challenges discussed for German OHSR are equally present in other countries. Thus, this position paper can be used to initiate fruitful discussions in other countries