Fabiano Bini

Microtensile measurements of single trabeculae stiffness in human femur

In this paper, the authors perform microtensile tests of single trabeculae excised from a human femur head. One of the main issues of this work is to establish some experimental procedures for preparing and testing the specimens. The use of a well-characterized microtensile apparatus allows for a low intraspecimen dispersion of the measured stiffness. Tensile/compressive tests were chosen because they appear less sensitive to errors in the cross-sectional area measurements with respect to bending tests. By these considerations, some tensile/compressive tests of plate-like trabecular specimens have been carried out. Typical stiffness values are 74.2+/-0.7Nmm(-1) for tensile tests, and 58.9+/-0.6Nmm(-1) for compressive test. Another compressive test performed on a shorter specimen yielded a stiffness value of 148.3+/-5.3Nmm(-1). The maximum applied load was about 0.5N. Rough measurements of specimens sizes yielded a Youngs modulus value ranging from 1.41 to 1.89GPa.

How to Measure Cerebral Correlates of Emotions in Marketing Relevant Tasks

Nowadays, there is a growing interest in measuring emotions through the estimation of cerebral variables. Several techniques and methods are used and debated in neuroscience. In such a context, the present paper provides examples of time-varying variables related to the estimation of emotional valence, arousal and Approach-Withdrawal behavior in marketing relevant contexts. In particular, we recorded electroencephalographic (EEG), galvanic skin response (GSR) and heart rate (HR) in a group of healthy subjects while they are watching different TV commercials. Specifically, results obtained in the Experiment 1 shows a significant increase of cortical power spectral density across left frontal areas in the alpha band and an enhance of cardiac activity during the observation of TV commercials that have been judged pleasant. In the Experiment 2, frontal EEG asymmetry, GSR and HR measurements are used to draw cognitive and emotional indices in order to track the subject’s internal state frame by frame of the commercial. A specific case study shows how the variations of the defined Approach-Withdrawal and emotional indices can distinguish the reactions of younger adults from the older ones during the observation of a funny spot. This technology could be of help for marketers to overcome some of the drawbacks of the standard marketing tools (e.g., interviews, focus groups) usually adopted during the analysis of the emotional perception of advertisements.

Design Concepts, Fabrication and Advanced Characterization Methods of Innovative Piezoelectric Sensors Based on ZnO Nanowires.

Micro- and nano-scale materials and systems based on zinc oxide are expected to explode in their applications in the electronics and photonics, including nano-arrays of addressable optoelectronic devices and sensors, due to their outstanding properties, including semiconductivity and the presence of a direct bandgap, piezoelectricity, pyroelectricity and biocompatibility. Most applications are based on the cooperative and average response of a large number of ZnO micro/nanostructures. However, in order to assess the quality of the materials and their performance, it is fundamental to characterize and then accurately model the specific electrical and piezoelectric properties of single ZnO structures. In this paper, we report on focused ion beam machined high aspect ratio nanowires and their mechanical and electrical (by means of conductive atomic force microscopy) characterization. Then, we investigate the suitability of new power-law design concepts to accurately model the relevant electrical and mechanical size-effects, whose existence has been emphasized in recent reviews.

Current–Voltage Characteristics of ZnO Nanowires Under Uniaxial Loading

The charge transport in zinc-oxide piezosemiconductive nanowires under purely vertical compressive or tensile strains is investigated. For simplicity, only the additional band bending originated by the piezoelectric charges has been accounted for. Moreover, a constant volumetric piezoelectric charge density is assumed, distributed within a maximum distance δpiezo from the two junctions between the metal ends and the nanowire. Examples demonstrate that the carrier concentration, the energy conduction band profile, and the current-voltage characteristics significantly depend on δpiezo. Therefore, we propose the use of current- voltage measurements to obtain information on δpiezo in strained piezosemiconductors.

Variability of morphometric parameters of human trabecular tissue from coxo-arthritis and osteoporotic samples

Morphometric and architectural bone parameters change in diseases such as osteoarthritis and osteoporosis. The mechanical strength of bone is primarily influenced by bone quantity and quality. Bone quality is defined by parameters such as trabecular thickness, trabecular separation, trabecular density and degree of anisotropy that describe the micro-architectural structure of bone. Recently, many studies have validated microtomography as a valuable investigative technique to assess bone morphometry, thanks to micro-CT non-destructive, non-invasive and reliability features, in comparison to traditional techniques such as histology. The aim of this study is the analysis by micro-computed tomography of six specimens, extracted from patients affected by osteoarthritis and osteoporosis, in order to observe the tridimensional structure and calculate several morphometric parameters.

Harmony as a convergence attractor that minimizes the energy expenditure and variability in physiological gait and the loss of harmony in cerebellar ataxia

BACKGROUND The harmony of the human gait was recently found to be related to the golden ratio value (ϕ). The ratio between the duration of the stance and that of the swing phases of a gait cycle was in fact found to be close to ϕ, which implies that, because of the fractal property of autosimilarity of that number, the gait ratios stride/stance, stance/swing, swing/double support, were not significantly different from one another. We studied a group of patients with cerebellar ataxia to investigate how the differences between their gait ratios and the golden ratio are related to efficiency and stability of their gait, assessed by energy expenditure and stride-to-stride variability, respectively. METHODS The gait of 28 patients who were affected by degenerative cerebellar ataxia and of 28 healthy controls was studied using a stereophotogrammetric system. The above mentioned gait ratios, the energy expenditure estimated using the pelvis reconstructed method and the gait variability in terms of the stride length were computed, and their relationships were analyzed. Matching procedures have also been used to avoid multicollinearity biases. FINDINGS The gait ratio values of the patients were farther from the controls (and hence from ϕ), even in speed matched conditions (P=0.011, Cohens D=0.76), but not when the variability and energy expenditure were matched between the two groups (Cohens D=0.49). In patients with cerebellar ataxia, the farther the stance-swing ratio was from ϕ, the larger the total mechanical work (R2adj=0.64). Further, a significant positive correlation was observed between the difference of the gait ratio from the golden ratio and the severity of the disease (R=0.421, P=0.026). INTERPRETATION Harmony of gait appears to be a benchmark of physiological gait leading to physiological energy recovery and gait reliability. Neurorehabilitation of patients with ataxia might benefit from the restoration of harmony of their locomotor patterns.

The connection between anthropometry and gait harmony unveiled through the lens of the golden ratio

In nature, many systems have a harmonic organization due to their fractal structure related to an irrational number called golden ratio. That is a constant proportion found in phases of human gait cycle, and is also found in the lengths of human body segments. In this study we tested if artificial alterations in anthropometric proportions may alter gait proportions. Twenty healthy subjects (29.15±5.66years) were enrolled in this study and asked to walk normally and with special shoes altering their anthropometric proportions. Further, to test if the relationship between gait phases and anthropometry could be due to the pendular mechanism of walking, subjects were also asked to walk with extra masses located on their shanks. Results showed that the artificial alteration of body segment proportions affected the gait ratio based on the proportion of time between stance and swing (p=0.015). Conversely, no changes occurred during walking in weighted condition (p=0.394). These results confirm the connection between anthropometric proportions and gait ratio, and suggest the idea that humans may have evolved into the actual anthropometric proportions for favoring a walking having a golden ratio based harmony, but research is required to verify this hypothesis.

Performance tests of sonographic instruments for the measure of flow speed

This paper describes the performance test of the pulsed Doppler feature of clinical ultrasound platforms of various manufacturers via a blood flow phantom. This is made up by a tissue mimicking material containing a blood mimicking fluid which circulates in a vessel with a constant mean velocity by means of a centrifuge pump. From the digitized images of the pulsed Doppler spectra over time, the mean and maximum velocities have been computed with a software package developed by the Authors. For laminar flows with a mean velocity ranging from 1,1 plusmn 0,7 cm/s and 12,7 plusmn 0,7 cm/s, measurements on the blood mimicking fluid were obtained using 7 different ultrasound scanner platforms, equipped with phased array and convex array probes. The pooled data have shown an overestimation of the mean velocity, from over 200 percent down to about 40 percent, depending on nominal flow rate and ultrasound equipment composition.

A New Neurocognitive Interpretation of Shoulder Position Sense during Reaching: Unexpected Competence in the Measurement of Extracorporeal Space

Background. The position sense of the shoulder joint is important during reaching. Objective. To examine the existence of additional competence of the shoulder with regard to the ability to measure extracorporeal space, through a novel approach, using the shoulder proprioceptive rehabilitation tool (SPRT), during reaching. Design. Observational case-control study. Methods. We examined 50 subjects: 25 healthy and 25 with impingement syndrome with a mean age [years] of 64.52 +/− 6.98 and 68.36 +/− 6.54, respectively. Two parameters were evaluated using the SPRT: the integration of visual information and the proprioceptive afferents of the shoulder (Test 1) and the discriminative proprioceptive capacity of the shoulder, with the subject blindfolded (Test 2). These tasks assessed the spatial error (in centimeters) by the shoulder joint in reaching movements on the sagittal plane. Results. The shoulder had proprioceptive features that allowed it to memorize a reaching position and reproduce it (error of 1.22 cm to 1.55 cm in healthy subjects). This ability was lower in the impingement group, with a statistically significant difference compared to the healthy group (p < 0.05 by Mann–Whitney test). Conclusions. The shoulder has specific expertise in the measurement of the extracorporeal space during reaching movements that gradually decreases in impingement syndrome.

Technique for bone volume measurement from human femur head samples by classification of micro-CT image histograms

INTRODUCTION Micro-CT analysis is a powerful technique for a non-invasive evaluation of the morphometric parameters of trabecular bone samples. This elaboration requires a previous binarization of the images. A problem which arises from the binarization process is the partial volume artifact. Voxels at the external surface of the sample can contain both bone and air so thresholding operates an incorrect estimation of volume occupied by the two materials. AIM The aim of this study is the extraction of bone volumetric information directly from the image histograms, by fitting them with a suitable set of functions. METHODS Nineteen trabecular bone samples were extracted from femoral heads of eight patients subject to a hip arthroplasty surgery. Trabecular bone samples were acquired using micro-CT Scanner. Hystograms of the acquired images were computed and fitted by Gaussian-like functions accounting for: a) gray levels produced by the bone x-ray absorption, b) the portions of the image occupied by air and c) voxels that contain a mixture of bone and air. This latter contribution can be considered such as an estimation of the partial volume effect. RESULTS The comparison of the proposed technique to the bone volumes measured by a reference instrument such as by a helium pycnometer show the method as a good way for an accurate bone volume calculation of trabecular bone samples.