A low-cost real time virtual system for postural stability assessment at home

Background and objective

The degeneration of the balance control system in the elderly and in many pathologies requires measuring the equilibrium conditions very often. In clinical practice, equilibrium control is commonly evaluated by using a force platform (stabilometric platform) in a clinical environment.In this paper, we demonstrate how a simple movement analysis system, based on a 3D video camera and a 3D real time model reconstruction of the human body, can be used to collect information usually recorded by a physical stabilometric platform.

Methods

The algorithm used to reconstruct the human body model as a set of spheres is described and discussed. Moreover, experimental measurements and comparisons with data collected by a physical stabilometric platform are also reported. The measurements were collected on a set of 6 healthy subjects to whom a change in equilibrium condition was stimulated by performing an equilibrium task.

Results

The experimental results showed that more than 95% of data collected by the proposed method were not significantly different from those collected by the classic platform, thus confirming the usefulness of the proposed system.

Conclusions

The proposed virtual balance assessment system can be implemented at low cost (about 500$) and, for this reason, can be considered a home use medical device. On the contrary, astabilometric platform has a cost of about 10,000$ and requires periodical calibration. The proposed system does not require periodical calibration, as is necessary for stabilometric force platforms, and it is easy to use. In future, the proposed system with little integration can be used, besides being an emulator of a stabilometric platform, also to recognize and track, in real time, head, legs, arms and trunk, that is to collect information actually obtained by sophisticated optoelectronic systems.     

Optimal-tuning PID control of adaptive materials for structural efficiency

The objective of this paper was solving the optimization problem of lightweight stiffened structures modelled as a two-dimensional domain in an efficient computational way. The underlying premise was that mass should be distributed in an efficient way, so as to use a minimum amount of material to accomplish the mechanical function. This premise was expressed as a global, multi-objective optimization problem in which stiffness and mass were conflicting objectives. Alternative local evolution rules were implemented to update mass density or Young’s modulus at each step of the iterative procedure. The solution of the structural optimization problem was accomplished by a novel automatic procedure consisting of two consecutive stages of control and optimization. In the first stage of Proportional Integral Derivative (PID) control gains were manually selected whereas in the second stage the finding of optimal values of control gains, target, and cost indices was allowed. In this study a bone-like material was adopted and a thin slab was analysed as a sample problem.     

Beyond Haemostasis and Thrombosis: Platelets in Depression and Its Co-Morbidities

Alongside their function in primary haemostasis and thrombo-inflammation, platelets are increasingly considered a bridge between mental, immunological and coagulation-related disorders. This review focuses on the link between platelets and the pathophysiology of major depressive disorder (MDD) and its most frequent comorbidities. Platelet- and neuron-shared proteins involved in MDD are functionally described. Platelet-related studies performed in the context of MDD, cardiovascular disease, and major neurodegenerative, neuropsychiatric and neurodevelopmental disorders are transversally presented from an epidemiological, genetic and functional point of view. To provide a complete scenario, we report the analysis of original data on the epidemiological link between platelets and depression symptoms suggesting moderating and interactive effects of sex on this association. Epidemiological and genetic studies discussed suggest that blood platelets might also be relevant biomarkers of MDD prediction and occurrence in the context of MDD comorbidities. Finally, this review has the ambition to formulate some directives and perspectives for future research on this topic.     

Some results about the optimal LQG tracking problem

The optimal LQG tracking problem is studied both for available and for unavailable state and reference, assuming that the last variable is the addition of a known deterministic component and of a random noise component. In both cases the optimal solution exists, is unique, and the optimal control is a suitable affine function of the current state and reference variable (when they are available) or of the corresponding optimal estimates (when they are not available). The minimum cost function is expressed in closed form.     

P-selectin, E-selectin, and CD40L over time in chronic hemodialysis patients

The aim of this study was to measure P-selectin, E-selectin, and CD-4L levels over time in chronic hemodialysis (HD) patients. Thirty stable patients with end-stage renal failure undergoing chronic HD were included in the study. Blood samples were obtained before HD for measurement of P-selectin, E-selectin, and CD-40L. Measurements were performed at month 0 (T0), 3 (T2), 8 (T3), and 13 (T4). The levels of P-selectin, E-selectin, and CD40L were also analyzed according to the occurrence of cardiovascular disease (CVD) and to CVD-related mortality. The levels of CD40L and P-selectin changed significantly over time, decreasing at month 3 and 6 and returning at the T0 levels at month 13. Conversely, E-selectin levels did not. The levels of CD40L, P-selectin and E-selectin over time did not differ significantly between patients with age ≤ 65 or > 65 years, between patients with or without CVD, or between patients who died or who survived during the follow-up. In end-stage renal failure patients undergoing chronic HD, CD40L and P-selectin, but not E-selectin, showed a transient decrease over time, and the serum levels of these molecules were not associated with CVD or with CVD-related mortality.     

Effect of Ag-containing Nano-composite Active Packaging System on Survival of Alicyclobacillus acidoterrestris

ABSTRACT: The effectiveness of Ag⁺-based antimicrobial film in inhibiting the growth of an Alicyclobacillus acidoterrestris strain was assessed. The proposed active film was obtained by depositing via plasma an Ag-containing polyethylenoxide-like coating on a polyethylene layer. Tests were conducted at 44 °C, monitoring the viable cell concentration of the investigated microorganism into 2 different media: acidified malt extract broth and apple juice. Results indicate that the investigated active film successfully inhibited the growth of A. acidoterrestris in both media. Results also indicate that the effectiveness of the film depends on the type of medium tested.     

An efficient adaptive algorithm for edge detection based on the likelihood ratio test

The edge detection problem in blurred and noisy 2‐D signals is dealt with. An adaptive signal processing algorithm is proposed which marks edge points according to an hypothesis test which compares the likelihoods of two models describing the local signal behaviour in the two cases of absence/presence of an edge. The two models are identified by a regularized least squares estimation algorithm, obtaining a numerically efficient procedure, quite robust with respect to additive noise and blurr perturbation. No global thresholding or data prefiltering is required. Copyright © 2002 John Wiley & Sons, Ltd.     

22 Cr 5 Ni duplex and 25 Cr 7 Ni superduplex stainless steel: Hydrogen influence on fatigue crack propagation resistance

Duplex stainless steels (DSS) fatigue crack propagation resistance is strongly affected by both microstructure and environment. In this work, environment influence on the fatigue crack propagation in a 22 Cr 5 Ni duplex and in a 25 Cr 7 Ni superduplex stainless steels is investigated considering three different stress ratios (R = K_min/K_max = 0.1, 0.5, 0.75). Tests are performed according to ASTM E 647 standard, both in air and under hydrogen charging conditions (0.1 M H₂SO₄ + 0.01 M KSCN aqueous solution, ?0.9 V/SCE). Crack fracture surfaces are extensively analysed by means of a scanning electron microscope. Furthermore, crack paths are investigated by means of a crack profile analysis performed through a light optical microscope. Nickel coated fracture surface sections obtained for constant ΔK values are considered in order to analyse the loading (R values) and environment influence on fatigue crack paths.     

Fatigue crack propagation damaging micromechanisms in ductile cast irons

Ductile iron discovery in 1948 gave a new lease on life to the cast iron family. In fact, these cast irons are characterized both by a high castability and by high toughness values, combining cast irons and steel good properties. Ductile cast irons are also characterized by high fatigue crack propagation resistance, although this property is still not widely investigated.In the present work, three different ferritic–pearlitic ductile cast irons, characterized by different ferrite/pearlite volume fractions, and an austempered ductile cast iron were considered. Their fatigue crack propagation resistance was investigated in air by means of fatigue crack propagation tests according to ASTM E647 standard, considering three different stress ratios (R = K_min/K_max = 0.1; 0.5; 0.75). Crack paths were investigated by means of a crack path profile analysis performed with an optical microscope. Crack surfaces were extensively analysed by means of a scanning electron microscope both considering a traditional procedure and performing a quantitative analysis of 3D reconstructed surfaces, mainly focusing graphite nodules debonding.