Fueled by a Fearful Leader: When, to What Extent and How Leader Fear of COVID-19 Promotes Employee Performance

The literature generally surmises that negative affective states of leaders are detrimental to leader effectiveness and work outcomes. Taking the opposite view, this study explores how the negative affective experiences of leaders related to COVID-19 may foster team commitment and employee performance. By integrating personality systems interaction theory, cognitive appraisal theory, and the literature on stress-based emotions, we develop a model that clarifies when, how, and to what extent leader fearful states related to COVID-19 drive employee performance. Using three-wave and multisource data from 579 employees and their leaders from 69 teams, we found that among leaders who exhibited higher levels of positive affectivity, leader fear of COVID-19 indirectly fostered employee performance via the mediating roles of leader promotion of team goals and team commitment. Moreover, these moderated indirect effects were strongest at moderate levels of leader fear of COVID-19. We discuss the theoretical and practical implications of these findings for research on leader affective states

Local Hidden Variable Theories for Quantum States

While all bipartite pure entangled states violate some Bell inequality, the relationship between entanglement and non-locality for mixed quantum states is not well understood. We introduce a simple and efficient algorithmic approach for the problem of constructing local hidden variable theories for quantum states. The method is based on constructing a so-called symmetric quasi-extension of the quantum state that gives rise to a local hidden variable model with a certain number of settings for the observers Alice and Bob.Comment: 8 pages Revtex; v2 contains substantial changes, a strengthened main theorem and more reference

Use of fluent for the development of a di-si engine

The recent surge of electric vehicles has put pressure on the development and manufacture of batteries. However, batteries are still expensive, bulky and heavy, creating the need for inboard electricity generation using an internal combustion engine, usually referred as “range extender”. This paper presents the initial development of a DI-SI engine to work as range extender, focusing on the interaction between fuel spray and airflow inside the combustion chamber. To enable efficient combustion of lean and extra lean mixtures, a technique called stratified charge, is used. With direct injection spark ignition (DI-SI) engines it is important, under part load, to direct the fuel spray to the vicinities of the spark plug, enabling a fast and stable combustion of a lean mixture. A rich mixture region is created near the spark plug allowing an easy kernel formation and development. There are three types of systems for “directing” the fuel spray towards the spark plug: wall guided, air guided and spray guided. The developed design is a mixture of wall and air guided systems and the idea is to inject the spray towards the piston crown and to divert it to the spark plug location by the barrel swirl existent within the combustion chamber at this time. The system development was carried out using CFD FLUENT code. The study comprises three parts, the design of the components and its location (combustion chamber, piston crown, intake passage and injector location and aim), the air flow modeling and finally, the two phase modelling. A simple engine geometry and mesh were created in the Ansys CFD software. The air flow was considered to be transient, incompressible, Newtonian and viscous turbulent. The turbulence model used was the standard k-ε model, since it is the most common, simple and well-known model of turbulence. The spray has been simulated using the Discrete Phase Model. The Lagrangian discrete phase model in Fluent™ follows the Euler-Lagrange approach, where the fluid phase is treated as a continuum by solving the time-averaged Navier-Stokes equations, while the dispersed phase is solved by tracking a large number of particles through the calculated flow field. Preliminary results are now being obtained.MIT Portugal, Fundação para a Ciência e a Tecnologia (FCT

Generalized phonon-assisted Zener tunneling in indirect semiconductors with non-uniform electric fields : a rigorous approach

A general framework to calculate the Zener current in an indirect semiconductor with an externally applied potential is provided. Assuming a parabolic valence and conduction band dispersion, the semiconductor is in equilibrium in the presence of the external field as long as the electronphonon interaction is absent. The linear response to the electron-phonon interaction results in a non-equilibrium system. The Zener tunneling current is calculated from the number of electrons making the transition from valence to conduction band per unit time. A convenient expression based on the single particle spectral functions is provided, enabling the numerical calculation of the Zener current under any three-dimensional potential profile. For a one dimensional potential profile an analytical expression is obtained for the current in a bulk semiconductor, a semiconductor under uniform field and a semiconductor under a non-uniform field using the WKB (Wentzel-Kramers-Brillouin) approximation. The obtained results agree with the Kane result in the low field limit. A numerical example for abrupt p - n diodes with different doping concentrations is given, from which it can be seen that the uniform field model is a better approximation than the WKB model but a direct numerical treatment is required for low bias conditions.Comment: 29 pages, 7 figure

Evaluation of resistive-plate-chamber-based TOF-PET applied to in-beam particle therapy monitoring

Particle therapy is a highly conformal radiotherapy technique which reduces the dose deposited to the surrounding normal tissues. In order to fully exploit its advantages, treatment monitoring is necessary to minimize uncertainties related to the dose delivery. Up to now, the only clinically feasible technique for the monitoring of therapeutic irradiation with particle beams is Positron Emission Tomography (PET). In this work we have compared a Resistive Plate Chamber (RPC)-based PET scanner with a scintillation-crystal-based PET scanner for this application. In general, the main advantages of the RPC-PET system are its excellent timing resolution, low cost, and the possibility of building large area systems. We simulated a partial-ring scannerbeam monitoring, which has an intrinsically low positron yield compared to diagnostic PET. In addition, for in-beam PET there is a further data loss due to the partial ring configuration. In order to improve the performance of the RPC-based scanner, an improved version of the RPC detector (modifying the thickness of the gas and glass layers), providing a larger sensitivity, has been simulated and compared with an axially extended version of the crystal-based device. The improved version of the RPC shows better performance than the prototype, but the extended version of the crystal-based PET outperforms all other options. based on an RPC prototype under construction within the Fondazione per Adroterapia Oncologica (TERA). For comparison with the crystal-based PET scanner we have chosen the geometry of a commercially available PET scanner, the Philips Gemini TF. The coincidence time resolution used in the simulations takes into account the current achievable values as well as expected improvements of both technologies. Several scenarios (including patient data) have been simulated to evaluate the performance of different scanners. Initial results have shown that the low sensitivity of the RPC hampers its application to hadro

Improved quantum algorithms for the ordered search problem via semidefinite programming

One of the most basic computational problems is the task of finding a desired item in an ordered list of N items. While the best classical algorithm for this problem uses log_2 N queries to the list, a quantum computer can solve the problem using a constant factor fewer queries. However, the precise value of this constant is unknown. By characterizing a class of quantum query algorithms for ordered search in terms of a semidefinite program, we find new quantum algorithms for small instances of the ordered search problem. Extending these algorithms to arbitrarily large instances using recursion, we show that there is an exact quantum ordered search algorithm using 4 log_{605} N \approx 0.433 log_2 N queries, which improves upon the previously best known exact algorithm.Comment: 8 pages, 4 figure