Electronic noise in charge sensitive preamplifiers for X-ray spectroscopy and the benefits of a SiC input JFET

A comprehensive summary and analysis of the electronic noise affecting the resolution of X-ray, γ-ray and particle counting spectroscopic systems which employ semiconductor detectors and charge sensitive preamplifiers is presented. The noise arising from the input transistor of the preamplifier and its contribution to the total noise is examined. A model for computing the noise arising from the front-end transistor is also presented and theoretical calculations comparing the noise contribution of transistors made of different materials are discussed, emphasizing the advantages of wide bandgap transistor technology

The impact of the Center of Excellence governance on the definition of RPA KPIs : An exploratory case-study of the Dutch banking sector

Robotic Process Automation (RPA) has become a significant tool for organizations to increase effi-ciency and to cut costs, especially in the banking sector. However, the adoption of RPA is not as extensive as it could be. Research shows that a potential cause for this can be attributed to the defini-tion of Key Performance Indicators (KPIs) for RPA. According to the Instrumental Stakeholder The-ory when it comes to making organizational decisions, management should consider all the relevant stakeholder interests. This exploratory research aims to determine whether the Instrumental Stake-holder Theory can be applied to RPA-related decisions such as the definition of KPIs and therefore questions what the impact of the RPA Center of Excellence (CoE) governance model is on the defi-nition of KPIs for RPA. The focus of this paper is the Dutch banking sector and interviews were conducted with RPA stakeholders of two representative banks. The responders were divided accord-ing to the stakeholder group that they belonged to. The results of the analysis indicate that the CoE governance model indeed has an impact on the definition of RPA KPIs. Further research could be applied to determine the other influencing factors or two investigate the future potential of the com-bination of RPA with AI technology

IT Outsourcing Governance: Contracts, Relationships And Modes Of Control

The aim of this research is to provide insights into the interplay between contractual and relational governance in IT outsourcing arrangements. Current IT outsourcing literature has predominantly viewed the contract as a governance mechanism that establishes a framework for the supplier-client relationship, monitors behaviours and measures performance. Our study departs from this high level view and using the Foucauldian notion of governmentality, sheds light upon the conjunction of formal and social control that the contract manifests. Along these lines, our analysis will provide insights into the role of the contract in the creation of “reflexive self-control” and its potential to contribute to the establishment of shared norms, values and goals

Bayesian Channel Estimation Techniques for AF MIMO Relaying Systems

In this paper, we consider the fundamental problem of channel estimation in multiple-input multiple-output (MIMO) amplify-and-forward (AF) relaying systems operating over random channels. Using the Bayesian framework, linear minimum mean square error (LMMSE) and expectation-maximization (EM) based maximum a posteriori (MAP) channel estimation algorithms are developed, that provide the destination with full knowledge of all channel parameters involved in the transmission. The performance of the proposed algorithms is evaluated in terms of the mean square error (MSE) as a function of the signal-to-noise ratio (SNR) during the training interval. Our simulation results show that the incorporation of prior knowledge into the channel estimation algorithm offers improved performance, especially in the low SNR regime

Empowering users with medical artificial intelligence technologies

Medical AI technologies promise to empower their users in managing their health. We develop a research model aiming to explain the role of user empowerment and resistance on the continuous use intention of medical AI technologies. The model was tested with data from 306 users of the Left-Hand Doctor chatbot in China. Users value the emotional support, responsiveness and accessibility of the chatbot. These features provide a strong explanation of user empowerment which in turn supports continuous use intention. While resistance to medical AI technologies negatively affects continuous use intention, it does not weaken the positive effects of empowerment. The research contributes to our knowledge of what user empowerment means and how it can support sustainable engagement with medical AI technologies. It further guides developers to more comprehensively consider similar user experience elements and positive outcomes of AI technologies in other application areas

Channel Tracking for AF MIMO Relaying Systems

In this paper, we consider the problem of channel estimation in multiple-input multiple-output (MIMO) amplifyand- forward (AF) relaying systems operating over time varying channels. Only data at the receiving end are assumed available for the estimation. By employing a first-order autoregressive (AR) model for characterizing the time-varying nature of the channels to be estimated, we derive an expectation-maximization (EM) Kalman filter (KF) that utilizes the received signal at the destination to track the individual channel links. The extended KF algorithm is also derived and compared to the proposed EM-based KF. Our simulation results show that the proposed EM-based KF offers better estimation performance with less complexity when compared to the EKF algorithm

Characterization of room temperature AlGaAs soft X-ray mesa photodiodes

Results characterising a set of nine prototype Al0.8Ga0.2As p+–i–n+ mesa photodiodes (400 µm diameter, 1.7 µm i layer) are presented. The results show the performance of the devices as room temperature spectroscopic photon counting soft X-ray detectors. The responses of the photodiodes to illumination with an 55Fe radioisotope X-ray source were measured using a low noise charge sensitive preamplifier; the energy resolutions measured with the devices were consistent with each other and had a mean FWHM at 5.9 keV of 1.27 keV. The devices are the thickest (highest detection efficiency) AlGaAs X-ray spectroscopic mesa photodiodes reported in the literature to date. They also have better energy resolution than all previously reported non-avalanche AlGaAs X-ray detectors of the same area

X-ray spectrometer with a low-cost SiC photodiode

A low-cost Commercial-Off-The-Shelf (COTS) 4H-SiC 0.06 mm2 UV p-n photodiode was coupled to a low-noise charge-sensitive preamplifier and used as photon counting X-ray spectrometer. The photodiode/spectrometer was investigated at X-ray energies from 4.95 keV to 21.17 keV: a Mo cathode X-ray tube was used to fluoresce eight high-purity metal foils to produce characteristic X-ray emission lines which were used to characterise the instrument. The energy resolution (full width at half maximum, FWHM ) of the spectrometer was found to be 1.6 keV to 1.8 keV, across the energy range. The energy linearity of the detector/spectrometer (i.e. the detector’s charge output per photon as a function of incident photon energy across the 4.95 keV to 21.17 keV energy range), as well as the count rate linearity of the detector/spectrometer (i.e. number of detected photons as a function of photon fluence at a specific energy) were investigated. The energy linearity of the detector/spectrometer was linear with an error <± 0.7 %; the count rate linearity of the detector/spectrometer was linear with an error <± 2 %. The use of COTS SiC photodiodes as detectors for X-ray spectrometers is attractive for nanosatellite/CubeSat applications (including solar flare monitoring), and for cost sensitive industrial uses

HOW DO OFFSHORING-RELATED CHANGES IN JOB CHARACTERISTICS AFFECT ONSHORE MANAGERS’ AFFECTIVE ORGANIZATIONAL COMMITMENT? THE MODERATING ROLE OF PERCEIVED ORGANIZATIONAL VALENCE

Offshoring—the transfer of work activities to providers in offshore countries—has for some time affected the nature of work in onshore locations. Not much is however known about the reactions of onshore job incumbents to such changes. In this article, we use a survey of UK firms to examine the relationship between perceived changes in onshore managers’ work characteristics induced by information systems offshoring and managers’ affective organizational commitment. We found that a perceived increase in onshore managers’ job complexity was associated with higher affective organizational commitment only if managers also perceived organizational valence, that is, only if they believed that information systems offshoring benefited their organization. A perceived increase in cross-cultural work was associated with higher affective organizational commitment, and this association was positively moderated by managers’ perceptions of organizational valence. Using the offshoring context, our findings provide insights into consequences of contemporary changes in the nature of work in developed countries and to explain the diverse reactions of onshore job incumbents to such changes.<br

Gallium Arsenide detectors for X-ray and electron (beta particle) spectroscopy

Results characterizing GaAs p+-i-n+ mesa photodiodes with a 10 µm i layer for their spectral response under illumination of X-rays and beta particles are presented. A total of 22 devices, having diameters of 200 µm and 400 µm, were electrically characterized at room temperature. All devices showed comparable characteristics with a measured leakage current ranging from 4 nA/cm2 to 67 nA/cm2 at an internal electric field of 50 kV/cm. Their unintentionally doped i layers were found to be almost fully depleted at 0 V due to their low doping density. 55Fe X-ray spectra were obtained using one 200 µm diameter device and one 400 µm diameter device. The best energy resolution (FWHM at 5.9 keV) achieved was 625 eV using the 200 µm and 740 eV using the 400 µm diameter device, respectively. Noise analysis showed that the limiting factor for the energy resolution of the system was the dielectric noise; if this noise was eliminated by better design of the front end of the readout electronics, the achievable resolution would be 250 eV. 63Ni beta particle spectra obtained using the 200 µm diameter device showed the potential utility of these detectors for electron and beta particle detection. The development of semiconductor electron spectrometers is important particularly for space plasma physics; such devices may find use in future space missions to study the plasma environment of Jupiter and Europa and the predicted electron impact excitation of water vapor plumes from Europa hypothesized as a result of recent Hubble Space Telescope (HST) UV observations