Single electron transistor strongly coupled to vibrations: Counting Statistics and Fluctuation Theorem

Using a simple quantum master equation approach, we calculate the Full Counting Statistics of a single electron transistor strongly coupled to vibrations. The Full Counting Statistics contains both the statistics of integrated particle and energy currents associated to the transferred electrons and phonons. A universal as well as an effective fluctuation theorem are derived for the general case where the various reservoir temperatures and chemical potentials are different. The first relates to the entropy production generated in the junction while the second reveals internal information of the system. The model recovers Franck-Condon blockade and potential applications to non-invasive molecular spectroscopy are discussed.Comment: extended discussion, to appear in NJ

Understandig the Role of Scenarios in Swiss Energy Research

Energy scenarios link long-term policy goals to near-term decisions and may thus guide the transition to more sustainable energy systems. Yet, systematic empirical analyses of how energy scenarios are understood and used by relevant actors are rare. This working paper addresses the situation in Switzerland, where several competing public energy scenarios have been developed by different organisations in reaction to the government’s decision to phase out nuclear power. The analysis focuses on the energy research community, which has a double role in the dissemination of scenario-based insights: On the one hand, researchers develop energy scenarios which may in turn be used by decision-makers in policy and industry to create or assess action alternatives. On the other hand, many researchers are scenario users themselves. We conducted 13 structured in-depth interviews with energy researchers. The sample covers a wide scope of institutions and disciplinary backgrounds, including economics, engineering, geography, sociology, and law. We find that while most researchers do use energy scenarios, there are, essentially, two contrasting types of scenario use among them: One group of researchers, which we labelled divers, is interested in very specific data and assumptions that it wants to fully understand. A second group, which we labelled sailors, refers to the results of a scenario analysis in a more general manner. We identified different interpretations of scenario content between sailors and divers. These discrepancies are a result of the highly specialised modelling activities on which energy scenarios are based. Implicit knowledge that is generated during the process of developing energy sce-narios is inaccessible to most scenarios users. We therefore conclude the study with a discussion about the usefulness of participative stakeholder involvement and scenario documentation that is adjusted to the interests and competencies of its users. Because energy scenarios increasingly serve as a scientifically derived information basis for societal debates about energy transitions, their use needs to be studied more extensively

PET/CT-guided biopsies of metabolically active bone lesions: applications and clinical impact

Purpose: In a minority of cases a definite diagnosis and stage grouping in cancer patients is not possible based on the imaging information of PET/CT. We report our experience with percutaneous PET/CT-guided bone biopsies to histologically verify the aetiology of hypermetabolic bone lesions. Methods: We retrospectively reviewed the data of 20 consecutive patients who underwent multimodal image-guided bone biopsies using a dedicated PET/CT system in a step-by-step technique. Technical and clinical success rates of PET/CT-guided biopsies were evaluated. Questionnaires were sent to the referring physicians to assess the impact of biopsies on patient management and to check the clinical need for PET/CT-guided biopsies. Results: Clinical indications for biopsy were to histologically verify the aetiology of metabolically active bone lesions without a morphological correlate confirming the suspicion of metastases in 15 patients, to determine the origin of suspected metastases in 3 patients and to evaluate the appropriateness of targeted therapy options in 2 patients. Biopsies were technically successful in all patients. In 19 of 20 patients a definite histological diagnosis was possible. No complications or adverse effects occurred. The result of PET/CT-guided bone biopsies determined a change of the planned treatment in overall 56% of patients, with intramodality changes, e.g. chemotherapy with palliative instead of curative intent, and intermodality changes, e.g. systemic therapy instead of surgery, in 22 and 50%, respectively. Conclusion: PET/CT-guided bone biopsies are a promising alternative to conventional techniques to make metabolically active bone lesions—especially without a distinctive morphological correlate—accessible for histological verification. PET/CT-guided biopsies had a major clinical impact in patients who otherwise cannot be reliably stage grouped at the time of treatment decision

Isotope independent determination of PET/CT modulation transfer functions from phantom measurements on spheres.

PURPOSE A PET/CT system's imaging capabilities are best described by its point spread function (PSF) in the spatial domain or equivalently by its modulation transfer function (MTF) in the spatial frequency domain. Knowing PSFs or MTFs is a prerequisite for many numerical methods attempting to improve resolution and to reduce the partial volume effect. In PET/CT, the observed PSF is a convolution of the system's intrinsic imaging capabilities including image reconstruction (PSF0) and the positron range function (PRF) of the imaged β(+) emitting isotope. A PRF describes the non-Gaussian distribution of β(+) annihilation events around a hypothetical point source. The main aim was to introduce a new method for determining a PET/CT system's intrinsic MTF (MTF0) from phantom measurements of hot spheres independently of the β(+) emitting isotope used for image acquisition. Secondary aim was to examine non-Gaussian and nonlinear MTFs of a modern iterative reconstruction algorithm. METHODS PET/CT images of seven phantom spheres with volumes ranging from 0.25 to 16 ml and filled either with (18)F or with (68)Ga were acquired and reconstructed using filtered back projection (FBP). MTFs were modeled with linear splines. The spline fit iteratively minimized the mean squared error between the acquired PET/CT image and a convolution of the thereof derived PSF with a numerical representation of the imaged hot phantom sphere. For determining MTF0, the numerical sphere representations were convolved with a PRF, simulating a fill with either (18)F or (68)Ga. The MTFs determined by this so-called MTF fit method were compared with MTFs derived from point source measurements and also compared with MTFs derived with a previously published PSF fit method. The MTF fit method was additionally applied to images reconstructed by a vendor iterative algorithm with PSF recovery (Siemens TrueX). RESULTS The MTF fit method was able to determine (18)F and (68)Ga dependent MTFs and MTF0 from FBP reconstructed images. Root-mean-square deviation between fit determined MTFs and point source determined MTFs ranged from 0.023 to 0.039. MTFs from Siemens TrueX reconstructions varied with size of the imaged sphere. CONCLUSIONS MTF0 can be determined regardless of the imaged isotope, when using existing PRF models for the MTF fit method presented. The method proves that modern iterative PET/CT reconstruction algorithms have nonlinear imaging properties. This behaviour is not accessible by point source measurements. MTFs resulting from these clinically applied algorithms need to be estimated from objects of similar geometry to those intended for clinical imaging

Threefold rotational symmetry in hexagonally shaped core–shell (In,Ga)As/GaAs nanowires revealed by coherent X-ray diffraction imaging

Coherent X-ray diffraction imaging at symmetric hhh Bragg reflections was used to resolve the structure of GaAs/In$_{0.15}$Ga$_{0.85}$As/GaAs core–shell–shell nanowires grown on a silicon (111) substrate. Diffraction amplitudes in the vicinity of GaAs 111 and GaAs 333 reflections were used to reconstruct the lost phase information. It is demonstrated that the structure of the core–shell–shell nanowire can be identified by means of phase contrast. Interestingly, it is found that both scattered intensity in the (111) plane and the reconstructed scattering phase show an additional threefold symmetry superimposed with the shape function of the investigated hexagonal nanowires. In order to find the origin of this threefold symmetry, elasticity calculations were performed using the finite element method and subsequent kinematic diffraction simulations. These suggest that a non-hexagonal (In,Ga)As shell covering the hexagonal GaAs core might be responsible for the observation

Threefold rotational symmetry in hexagonally shaped core–shell (In,Ga)As/GaAs nanowires revealed by coherent X-ray diffraction imaging

Coherent X-ray diffraction imaging at symmetric hhh Bragg reflections was used to resolve the structure of GaAs/In0.15Ga0.85As/GaAs core–shell–shell nanowires grown on a silicon (111) substrate. Diffraction amplitudes in the vicinity of GaAs 111 and GaAs 333 reflections were used to reconstruct the lost phase information. It is demonstrated that the structure of the core–shell–shell nanowire can be identified by means of phase contrast. Interestingly, it is found that both scattered intensity in the (111) plane and the reconstructed scattering phase show an additional threefold symmetry superimposed with the shape function of the investigated hexagonal nanowires. In order to find the origin of this threefold symmetry, elasticity calculations were performed using the finite element method and subsequent kinematic diffraction simulations. These suggest that a non-hexagonal (In,Ga)As shell covering the hexagonal GaAs core might be responsible for the observation

Evidenzkarten-basierte Sensorfusion zur Umfelderkennung und Interpretation in der Ernte

Korthals T, Skiba A, Krause T, Jungeblut T. Evidenzkarten-basierte Sensorfusion zur Umfelderkennung und Interpretation in der Ernte. In: Ruckelshausen A, Meyer-Aurich A, Rath T, Recke G, Theuvsen B, eds. Informatik in der Land-, Forst- und Ernährungswirtschaft - Intelligente Systeme - Stand der Technik und neue Möglichkeiten. 2016: 97-100