Existence and multiplicity for elliptic problems with quadratic growth in the gradient

We show that a class of divergence-form elliptic problems with quadratic growth in the gradient and non-coercive zero order terms are solvable, under essentially optimal hypotheses on the coefficients in the equation. In addition, we prove that the solutions are in general not unique. The case where the zero order term has the opposite sign was already intensively studied and the uniqueness is the rule.Comment: To appear in Comm. PD

Diffeomorphism-invariant properties for quasi-linear elliptic operators

For quasi-linear elliptic equations we detect relevant properties which remain invariant under the action of a suitable class of diffeomorphisms. This yields a connection between existence theories for equations with degenerate and non-degenerate coerciveness.Comment: 16 page

Simulation of high Schmidt number fluids with dissipative particle dynamics: Parameter identification and robust viscosity evaluation

Dissipative particle dynamics (DPD) is a widely used coarse-grained technique for the simulation of complex fluids. Although the method is capable of describing the hydrodynamics of any fluid, the common choice of DPD parameters, such as friction coefficient γ, dissipative cutoff radius , coarse-graining factor Nm and weighting function exponent s, unrealistically leads to the simulation of liquid water with a low Schmidt number Sc at standard pressure and temperature. In this work we explored the influence of these parameters, finding the set of parameters needed to properly simulate liquid water. Particular attention was devoted to the numerical techniques to calculate the transport properties from equilibrium simulations, especially in the calculation of the viscosity, comparing the most commonly adopted techniques and formulating a recipe that can be used for further investigations

Diffusion as a singular homogenization of the Frenkel-Kontorova model

International audienceIn this work, we consider a general fully overdamped Frenkel-Kontorova model. This model describes the dynamics of a infinite chain of particles, moving in a periodic landscape. Our aim is to describe the macroscopic behavior of this system. We study a singular limit corresponding to a high density of particles moving in a vanishing periodic landscape. We identify the limit equation which is a nonlinear diffusion equation. Our homogenization approach is done in the framework of viscosity solutions

A Novel Method for Vibrotactile Proprioceptive Feedback Using Spatial Encoding and Gaussian Interpolation

Objective: The bidirectional communication between the user and the prosthesis is an important requirement when developing prosthetic hands. Proprioceptive feedback is fundamental to perceiving prosthesis movement without the need for constant visual attention. We propose a novel solution to encode wrist rotation using a vibromotor array and Gaussian interpolation of vibration intensity. The approach generates tactile sensation that smoothly rotates around the forearm congruently with prosthetic wrist rotation. The performance of this scheme was systematically assessed for a range of parameter values (number of motors and Gaussian standard deviation). Methods: Fifteen able-bodied subjects and one individual with congenital limb deficiency used vibrational feedback to control the virtual hand in the target-achievement test. Performance was assessed by end-point error and efficiency as well as subjective impressions. Results: The results showed a preference for smooth feedback and a higher number of motors (8 and 6 versus 4). With 8 and 6 motors, the standard deviation, determining the sensation spread and continuity, could be modulated through a broad range of values (0.1 - 2) without a significant performance loss (error: ∼ 10%; efficiency: ∼ 30%). For low values of standard deviation (0.1-0.5), the number of motors could be reduced to 4 without a significant performance decrease. Conclusion: The study demonstrated that the developed strategy provided meaningful rotation feedback. Moreover, the Gaussian standard deviation can be used as an independent parameter to encode an additional feedback variable. Significance: The proposed method is a flexible and effective approach to providing proprioceptive feedback while adjusting the trade-off between sensation quality and the number of vibromotors

Idiopathic eosinophilic parotitis in an eight-year-old boy: a case report

<p>Abstract</p> <p>Introduction</p> <p>A number of medical conditions, some of them recently reported, are associated with an increased production of eosinophils. We report the first case of eosinophilic parotitis in the literature.</p> <p>Case presentation</p> <p>The patient was an eight-year-old Caucasian boy who presented with a two-year history of recurring acute parotitis with no fever. He had had a total of five episodes with no response to antibiotics, but remission had been achieved with oral corticosteroid therapy. We performed allergy tests for inhalant and food allergens and for haptens, but the results were all negative. The results of echography ruled out sialodochitis. Instead, a swab from the parotid duct led to the detection of a high number of eosinophils.</p> <p>Conclusions</p> <p>This report is first in the literature to describe a case of eosinophilic parotitis, and we suggest that a cytological assessment, which is quite simple yet rarely used by physicians, be performed when patients with parotitis of uncertain origin are under evaluation.</p

Human papillomavirus type 18 E5 oncoprotein cooperates with E6 and E7 in promoting cell viability and invasion and in modulating the cellular redox state

BACKGROUND High-risk human papillomaviruses (HR-HPVs) are the etiological agents of cervical cancer. Among them, types 16 and 18 are the most prevalent worldwide. The HPV genome encodes three oncoproteins (E5, E6, and E7) that possess a high transformation potential in culture cells when transduced simultaneously. In the present study, we analysed how these oncoproteins cooperate to boost key cancer cell features such as uncontrolled cell proliferation, invasion potential, and cellular redox state imbalance. Oxidative stress is known to contribute to the carcinogenic process, as reactive oxygen species (ROS) constitute a potentially harmful by-product of many cellular reactions, and an efficient clearance mechanism is therefore required. Cells infected with HR-HPVs can adapt to oxidative stress conditions by upregulating the formation of endogenous antioxidants such as catalase, glutathione (GSH), and peroxiredoxin (PRX). OBJECTIVES The primary aim of this work was to study how these oncoproteins cooperate to promote the development of certain cancer cell features such as uncontrolled cell proliferation, invasion potential, and oxidative stress that are known to aid in the carcinogenic process. METHODS To perform this study, we generated three different HaCaT cell lines using retroviral transduction that stably expressed combinations of HPV-18 oncogenes that included HaCaT E5-18, HaCaT E6/E7-18, and HaCaT E5/E6/E7-18. FINDINGS Our results revealed a statistically significant increment in cell viability as measured by MTT assay, cell proliferation, and invasion assays in the cell line containing the three viral oncogenes. Additionally, we observed that cells expressing HPV-18 E5/E6/E7 exhibited a decrease in catalase activity and a significant augmentation of GSH and PRX1 levels relative to those of E5, E6/E7, and HaCaT cells. MAIN CONCLUSIONS This study demonstrates for the first time that HPV-18 E5, E6, and E7 oncoproteins can cooperate to enhance malignant transformationANII: PD_NAC_2016_1_13332

Hannes Prosthesis Control Based on Regression Machine Learning Algorithms

The quality of life for upper limb amputees can be greatly improved by the adoption of poly-articulated myoelectric prostheses. Typically, in these applications, a pattern recognition algorithm is used to control the system by converting the recorded electromyographic activity (EMG) into complex multi-degrees of freedom (DoFs) movements. However, there is currently a trade-off between the intuitiveness of the control and the number of active DoFs. We here address this challenge by performing simultaneous multi-joint control of the Hannes system and testing several state-of-the-art classifiers to decode hand and wrist movements. The algorithms discriminated multi-DoF movements from forearm EMG signals of 10 healthy subjects reproducing hand opening-closing, wrist flexion-extension and wrist pronation-supination. We first explored the effect of the number of employed EMG electrodes on device performance through the classifiers optimization in terms of F1Score. We further improved classifiers by tuning their respective hyperparameters in terms of the Embedding Optimization Factor. Finally, three mono-lateral amputees tested the optimized algorithms to intuitively and simultaneously control the Hannes system. We found that the algorithms performances were similar to that of healthy subjects, particularly identifying the Non-Linear Regression classifier as the ideal candidate for prosthetic applications