The Gentle Art of Retroduction: Critical Realism, Cultural Political Economy and Critical Grounded Theory

This article, first, proposes critical grounded theory (CGT) as a way to develop systematically an array of methods and theoretical propositions into a coherent critical methodology for organization studies (and beyond). Second, it demonstrates CGT’s usefulness through a case study of competing recovery projects from the Icelandic financial crisis. CGT is developed in engagement with the emerging paradigm of cultural political economy (CPE) and its preferred method of critical discourse analysis (CDA). CPE analyses the evolution of ‘economic imaginaries’ in both their structural/material and semiotic/discursive dimensions. This requires a critical realist, multi-dimensional research strategy which emphasizes ethnographic methods and substantial theoretical and historical work. The proposed methodology of CGT enables a retroductive research process that combines deductive theoretical deskwork with inductive fieldwork enabled by grounded theory tools to analyse organizational process, stability and change

Possible indicators for low dimensional superconductivity in the quasi-1D carbide Sc3CoC4

The transition metal carbide Sc3CoC4 consists of a quasi-one-dimensional (1D) structure with [CoC4]_{\inft} polyanionic chains embedded in a scandium matrix. At ambient temperatures Sc3CoC4 displays metallic behavior. At lower temperatures, however, charge density wave formation has been observed around 143K which is followed by a structural phase transition at 72K. Below T^onset_c = 4.5K the polycrystalline sample becomes superconductive. From Hc1(0) and Hc2(0) values we could estimate the London penetration depth ({\lambda}_L ~= 9750 Angstroem) and the Ginsburg-Landau (GL) coherence length ({\xi}_GL ~= 187 Angstroem). The resulting GL-parameter ({\kappa} ~= 52) classifies Sc3CoC4 as a type II superconductor. Here we compare the puzzling superconducting features of Sc3CoC4, such as the unusual temperature dependence i) of the specific heat anomaly and ii) of the upper critical field H_c2(T) at T_c, and iii) the magnetic hysteresis curve, with various related low dimensional superconductors: e.g., the quasi-1D superconductor (SN)_x or the 2D transition-metal dichalcogenides. Our results identify Sc3CoC4 as a new candidate for a quasi-1D superconductor.Comment: 4 pages, 5 figure

Learning tethered perching for aerial robots

Aerial robots have a wide range of applications, such as collecting data in hard-to-reach areas. This requires the longest possible operation time. However, because currently available commercial batteries have limited specific energy of roughly 300 W h kg -1 , a drone's flight time is a bottleneck for sustainable long-term data collection. Inspired by birds in nature, a possible approach to tackle this challenge is to perch drones on trees, and environmental or man-made structures, to save energy whilst in operation. In this paper, we propose an algorithm to automatically generate trajectories for a drone to perch on a tree branch, using the proposed tethered perching mechanism with a pendulum-like structure. This enables a drone to perform an energy-optimised, controlled 180° flip to safely disarm upside down. To fine-tune a set of reachable trajectories, a soft actor critic-based reinforcement algorithm is used. Our experimental results show the feasibility of the set of trajectories with successful perching. Our findings demonstrate that the proposed approach enables energy-efficient landing for long-term data collection tasks

The molecular basis of TnrA control by glutamine synthetase in bacillus subtilis

© 2016 by The American Society for Biochemistry and Molecular Biology, Inc.TnrA is amaster regulator of nitrogen assimilation in Bacillus subtilis. This study focuses on the mechanism of how glutamine synthetase (GS) inhibits TnrA function in response to key metabolites ATP, AMP, glutamine, and glutamate. We suggest a model of two mutually exclusive GS conformations governing the interaction with TnrA. Inthe ATP-bound state (A-state), GS is catalytically active but unable to interact with TnrA. This conformation was stabilized by phosphorylated L-methionine sulfoximine (MSX), fixing the enzymein the transition state. When occupied by glutamine (or its analogue MSX), GS resides in a conformation that has high affinity for TnrA (Q-state). The A-and Q-state are mutually exclusive, and in agreement, ATP and glutamine bind to GS in a competitive manner. At elevated concentrations of glutamine, ATP is no longer able to bind GS and to bring it into the A-state. AMP efficiently competes with ATP and prevents formation of the A-state, thereby favoring GS-TnrA interaction. Surface plasmon resonance analysis shows that TnrA bound to a positively regulated promoter fragment binds GS in the Q-state, whereas it rapidly dissociates from a negatively regulated promoter fragment. These data imply that GS controls TnrA activity at positively controlled promoters by shielding the transcription factor in the DNA-bound state. Accordingtosize exclusion and multiangle light scattering analysis, the dodecameric GS can bind three TnrA dimers. The highly interdependent ligand binding properties of GS reveal this enzyme as a sophisticated sensor of the nitrogen and energy state of the cell to control the activity of DNA-bound TnrA

Monte-Carlo Simulations of Radiation-Induced Activation in a Fast-Neutron and Gamma- Based Cargo Inspection System

An air cargo inspection system combining two nuclear reaction based techniques, namely Fast-Neutron Resonance Radiography and Dual-Discrete-Energy Gamma Radiography is currently being developed. This system is expected to allow detection of standard and improvised explosives as well as special nuclear materials. An important aspect for the applicability of nuclear techniques in an airport inspection facility is the inventory and lifetimes of radioactive isotopes produced by the neutron and gamma radiation inside the cargo, as well as the dose delivered by these isotopes to people in contact with the cargo during and following the interrogation procedure. Using MCNPX and CINDER90 we have calculated the activation levels for several typical inspection scenarios. One example is the activation of various metal samples embedded in a cotton-filled container. To validate the simulation results, a benchmark experiment was performed, in which metal samples were activated by fast-neutrons in a water-filled glass jar. The induced activity was determined by analyzing the gamma spectra. Based on the calculated radioactive inventory in the container, the dose levels due to the induced gamma radiation were calculated at several distances from the container and in relevant time windows after the irradiation, in order to evaluate the radiation exposure of the cargo handling staff, air crew and passengers during flight. The possibility of remanent long-lived radioactive inventory after cargo is delivered to the client is also of concern and was evaluated.Comment: Proceedings of FNDA 201

Carcinoid tumours of the lung and the ’PEPPS’ approach: evaluation of preoperative bronchoscopic tumour debulking as preparation for subsequent parenchyma-sparing surgery

BACKGROUND: Preoperative bronchoscopic tumour ablation has been suggested as a beneficial treatment for bronchopulmonary carcinoid tumours, although data regarding its effects and long-term outcome are lacking. METHODS: In our case-matched cohort study with 208 patients with bronchopulmonary carcinoid tumours we investigated the role of preoperative bronchoscopic interventions before subsequent surgery and analysed the safety of this Procedure of Endobronchial Preparation for Parenchyma-sparing Surgery (PEPPS) based on metastasis and recurrence rates as well as survival data from 1991 to 2010. The subsequent surgery was classified into parenchyma-sparing procedures and classical lobectomies, bilobectomies and pneumonectomies. Data were obtained from the tumour registry and medical reports. Outcomes were the frequency of parenchyma-sparing surgery after bronchoscopic treatment as well as rates of metastasis, recurrence and survival. RESULTS: 132 of 208 carcinoids were located centrally. Among them, 77 patients could be recanalised preoperatively. After bronchoscopic preparation, the rate of subsequent parenchyma-sparing surgery methods was higher (p=0.021). The effect was measured by the number of segments removed. The 10-year survival rate was 89% (typical carcinoids) and 68% (atypical carcinoids), respectively. After applying PEPPS, long-term survival was slightly higher (p=0.23). Metastasis and recurrence rates showed no relevant differences between the bronchoscopically treated or non-treated groups, or between the two types of surgery classes or between the PEPPS and non-PEPPS groups. CONCLUSIONS: After preoperative bronchoscopic treatment, parenchyma-sparing surgery techniques can be applied more frequently. Furthermore, we detected no negative effects after PEPPS based on metastasis, recurrence and survival rates

A case study of boundary layer ventilation by convection and coastal processes

It is often assumed that ventilation of the atmospheric boundary layer is weak in the absence of fronts, but is this always true? In this paper we investigate the processes responsible for ventilation of the atmospheric boundary layer during a nonfrontal day that occurred on 9 May 2005 using the UK Met Office Unified Model. Pollution sources are represented by the constant emission of a passive tracer everywhere over land. The ventilation processes observed include shallow convection, turbulent mixing followed by large-scale ascent, a sea breeze circulation and coastal outflow. Vertical distributions of tracer are validated qualitatively with AMPEP (Aircraft Measurement of chemical Processing Export fluxes of Pollutants over the UK) CO aircraft measurements and are shown to agree impressively well. Budget calculations of tracers are performed in order to determine the relative importance of these ventilation processes. Coastal outflow and the sea breeze circulation were found to ventilate 26% of the boundary layer tracer by sunset of which 2% was above 2 km. A combination of coastal outflow, the sea breeze circulation, turbulent mixing and large-scale ascent ventilated 46% of the boundary layer tracer, of which 10% was above 2 km. Finally, coastal outflow, the sea breeze circulation, turbulent mixing, large-scale ascent and shallow convection together ventilated 52% of the tracer into the free troposphere, of which 26% was above 2 km. Hence this study shows that significant ventilation of the boundary layer can occur in the absence of fronts (and thus during high-pressure events). Turbulent mixing and convection processes can double the amount of pollution ventilated from the boundary layer