3,479 research outputs found
Leaders\u2019 competence and warmth: Their relationships with employees\u2019 well-being and organizational effectiveness
The aim of this work was to investigate competence and warmth \u2014 the two basic dimensions of social judgment \u2014 as dimensions employees use to evaluate their supervisors. A mediation model was tested in which supervisor\u2019s perceived competence and warmth were associated with relevant outcomes (lower burnout, weaker turnover intentions, more frequent citizenship behaviors) through the mediation of affective organizational commitment (AOC). In Study 1, data were collected from employees of a company in the water service sector. In Study 2, participants were financial promoters. In Study 3, the sample included employees from different organizations. As hypothesized, the perception of one\u2019s supervisor as competent (Studies 1-3) and warm (Study 3) was related to employees\u2019 lower burnout, weaker turnover intentions, more frequent prosocial behaviors through the mediation of AOC. Theoretical and practical implications of findings are discussed
Influence of non-structural localized inertia on free vibration response of thin-walled structures by variable kinematic beam formulations
Variable kinematic beam theories are used in this paper to carry out vibration analysis of isotropic thin-walled structures subjected to non-structural localized inertia. Arbitrarily enriched displacement fields for beams are hierarchically obtained by using the Carrera Unified Formulation (CUF). According to CUF, kinematic fields can be formulated either as truncated Taylor-like expansion series of the generalized unknowns or by using only pure translational variables by locally discretizing the beam cross-section through Lagrange polynomials. The resulting theories were, respectively, referred to as TE (Taylor Expansion) and LE (Lagrange Expansion) in recent works. If the finite element method is used, as in the case of the present work, stiffness and mass elemental matrices for both TE and LE beam models can be written in terms of the same fundamental nuclei. The fundamental nucleus of the mass matrix is opportunely modified in this paper in order to account for non-structural localized masses. Several beams are analysed and the results are compared to those from classical beam theories, 2D plate/shell, and 3D solid models from a commercial FEM code. The analyses demonstrate the ineffectiveness of classical theories in dealing with torsional, coupling, and local effects that may occur when
localized inertia is considered. Thus the adoption of higher-order beam models is mandatory. The results highlight the efficiency of the proposed models and, in particular, the enhanced capabilities of LE modelling approach, which is able to reproduce solid-like analysis with very low computational costs
Guest editorial of MAMS special issue on: Applications of Unified Formulation and advanced theories using several numerical approaches
Assessment of layerwise user-elements in Abaqus for static and free vibration analysis of variable stiffness composite laminates
In this work, user-elements (UEL) in Abaqus are taken a step forward into the high-order layerwise modelling of variable stiffness composite laminates with curvilinear fibre paths, extending the limited number of available literature on refined multilayered UEL models. Two layerwise UEL models with three discrete layers are here proposed, assigning to each layer the displacements of the first- and third-order shear deformation theories, thus named UEL1 and UEL3, respectively. A complete assessment of the models predictive capabilities is carried out by a comparison with available static and free vibration solutions in the literature â either for constant or variable stiffness laminates â considering various boundary and loading conditions, as well as thin and moderately thick plates. Numerical results demonstrate that the developed models are capable to render fairly accurate and computationally efficient results, with particular emphasis on the higher-order model for predicting the globalâlocal response behaviour of moderately thick plates
The n-acetyl phenylalanine glucosamine derivative attenuates the inflammatory/catabolic environment in a chondrocyte-synoviocyte co-culture system
Osteoarthritis (OA), the most prevalent degenerative joint disease, still lacks a true disease-modifying therapy. The involvement of the NF-ÎșB pathway and its upstream activating kinases in OA pathogenesis has been recognized for many years. The ability of the N-acetyl phenylalanine glucosamine derivative (NAPA) to increase anabolism and reduce catabolism via inhibition of IKKα kinase has been previously observed in vitro and in vivo. The present study aims to confirm the chondroprotective effects of NAPA in an in vitro model of joint OA established with primary cells, respecting both the crosstalk between chondrocytes and synoviocytes and their phenotypes. This model satisfactorily reproduces some features of the previously investigated DMM model, such as the prominent induction of ADAMTS-5 upon inflammatory stimulation. Both gene and protein expression analysis indicated the ability of NAPA to counteract key cartilage catabolic enzymes (ADAMTS-5) and effectors (MCP-1). Molecular analysis showed the ability of NAPA to reduce IKKα nuclear translocation and H3Ser10 phosphorylation, thus inhibiting IKKα transactivation of NF-ÎșB signalling, a pivotal step in the NF-ÎșB-dependent gene expression of some of its targets. In conclusion, our data confirm that NAPA could truly act as a disease-modifying drug in OA
Analytical modeling of panel flutter and active control in supersonic variable stiffness composite laminates
This work focuses on panel flutter and active control in supersonic variable stiffness composite laminates, making progress on the analytical modeling and combined exploration of curvilinear fiber composites tailoring and piezoelectric sensors/actuators, as promising structural design technologies, for aeroelastic control. The Classical Laminated Plate Theory and the First-Order Piston Theory are used as structural and aerodynamic models, respectively. Flutter analyses are carried out for simply supported plates, either purely elastic laminates or piezoelectric composite laminates. The tailor-ability of curvilinear fiber composites and the effect of proportional control are discussed. Ultimately, the presented results provide a comprehensive benchmark for future assessments
Mitral valve repair in heart failure
Mitral regurgitation (MR) is a frequent complication of endâstage heart failure. Historically, these patients were either managed medically or with mitral valve replacement, both associated with poor outcomes. Mitral valve repair via an âundersizedâ annuloplasty repair is safe and effectively corrects MR in heartâfailure patients. All of the observed changes contribute to reverse remodeling and restoration of the normal leftâventricular geometric relationship. Mitral valve repair offers a new strategy for patients with MR and endâstage heart failure.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/102643/1/ejhf00125-2.pd
Improvement of phemt intermodulation prediction through the accurate modelling of low-frequency dispersion effects
Large-signal dynamic modelling of III-V FETs
cannot be simply based on de i/v characteristics, when accurate
performance prediction is needed. In fact, dispersive phenomena
due to self-heating and/or traps (surface state densities and deep
level traps) must be taken into account since they cause
important deviations in the dynamic drain current.
In this paper, a recently proposed large-signal i/v measurement
setup is exploited to extract an empirical model for lowfrequency
dispersive phenomena in microwave electron devices.
This i/v model is then embedded into a microwave large-signal
PHEMT model. Eventually, a Ka-band highly linear power
amplifier, designed by Ericsson using the Triquint GaAs 0.25pm
PHEMT process, is used for model validation.
Excellent intermodulation distortion predictions are obtained
with different loads despite the extremely low power level of
IMD products involved. This entitles the proposed model to be
also used in the PA design process instead of conventional loadpull
techniques whenever the high-linearity specifications play a
major role
Uncommon 18F-FDG-PET/CT findings in patients affected by limbic encephalitis: Hyper-hypometabolic pattern with double antibody positivity and migrating foci of hypermetabolism
Autoimmune limbic encephalitis (LE) is a rare disorder; its diagnosis can be challenging.We report two uncommon cases of LE evaluated by brain 2-deoxy-2-[18F]fluoro-d-glucose (18F-FDG) positron emission tomography/ computed tomography describing themetabolic imaging patterns, which were different from those observed in previous studies: the first one presented an unprecedented 18F-FDG brain mixed pattern, involving also themidbrain, despite negative magnetic resonance imaging exams; the second one showed migrating foci of hypermetabolism, one of which turned into hypometabolism at a later examination
Thermal stress analysis of variable angle tow composite plates through high-order structural models
This work focuses on thermo-elastic analysis of Variable Angle Tow (VAT) composite plates. Emphasis is given to the through-the-thickness 3D stress component distributions as a consequence of constant temperature profiles. High-order structural models are used, in order to take into account the volumetric and the distortion contributions. The last contribute arise from boundary conditions or asymmetric staking sequences. Governing equations of the uncoupled thermo-elastic problem are derived in the domain of the Carrera Unified Formulation (CUF), which in turn is coupled with a classical finite element method to obtain opportune numerical solutions. The advantage of using CUF lies in the fact that different theories of structures can be implemented automatically and a critical study on the use of standard to high-order plate finite elements can be performed with ease. In this manner we classify models based on their efficiency and depending on the degree of accuracy needed, both in terms of displacements and stresses. Different numerical problems are considered and it is demonstrated that layerwise approximations are needed whenever shear stresses trends are of interest. Boundary Conditions influence more the choice of the adequate expansion theory otherwise
- âŠ