Studying upper-limb kinematics using inertial sensors

AIM: The aim of this study was to analyze scapulohumeral rhythm through nine physical properties that correspond to angular mobility, angular velocity, and acceleration in the three axes of space, obtained by inertial sensors. METHODS: This cross-sectional study recruited healthy young adult subjects. Descriptive and anthropometric independent variables related to age, gender, weight, size, and BMI were included. Nine physical properties were included corresponding to three dependent variables for each of three special axes: mobility angle (degrees), angular speed (degrees/second), and lineal acceleration (meters/seconds2), which were obtained thought the inertial measurement sensors with four inertial sensors (InertiaCube3™ Intersense Inc., Billerica, Massachusetts). Inertial sensors were placed in the right half of the body of each subject located in the middle third of the humerus slightly posterior, in the middle third of the upper spine of the scapula, in the flat part of the sternum, and the distal surface of the ulna and radius. RESULTS: Descriptive graphics of analytical tasks performed were obtained (figure 1). The main difference in mobility between the scapula and humerus was found in pitch axis for abduction ( = 107.6°, SD = 9.3°) and flexion ( = 113.1°, SD = 9.3°). CONCLUSION: This study shows how much each body segment contributes to upper-limb motion, and allows us to obtain grades of mobility provided by the scapula. Also, this study identified movement patterns, and supports inertial sensors as a useful device to analyze upper-limb kinematics. However, further studies with subjects with shoulder pathology should be carried out.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Studying upper-limb kinematic using inertial sensors embedded in smartphones

Background: In recent years, there have been investigations concerning upper-limbs kinematics by various devices. The latest generation of smartphones often includes inertial sensors with subunits which can detect inertial kinematics. The use of smartphones is presented as a convenient and portable analysis method for studying kinematics in terms of angular mobility and linear acceleration Objective: The aim of this study was to study humerus kinematics through six physical properties that correspond to angular mobility and acceleration in the three axes of space, obtained by a smartphone. Methods: This cross-sectional study recruited healthy young adult subjects. Descriptive and anthropometric independent variables related to age, gender, weight, size, and BMI were included. Six physical properties were included corresponding to two dependent variables for each of three special axes: mobility angle (degrees) and lineal acceleration (meters/seconds2), which were obtained thought the inertial measurement sensor embedded in the iPhone4 smartphone equipped with three two elements for the detection of kinematic variables: a gyroscope and an accelerometer. Apple uses an LIS302DL accelerometer in the iPhone4. The application used to obtain kinematic data was xSensor Pro, Crossbow Technology, Inc., available at the Apple AppStore. The iPhone4 has storage capacity of 20MB. The data-sampling rate was set to 32 Hz, and the data for each analytical task was transmitted as email for analysis and postprocessing The iPhone4 was placed in the right half of the body of each subject located in the middle third of the humerus slightly posterior snugly secured by a neoprene fixation belt. Tasks were explained concisely and clearly. The beginning and the end were decided by a verbal order by the researcher. Participants were placed standing, starting from neutral position, performing the following analytical tasks: 180º right shoulder abduction (eight repetitions) and, after a break of about 3 minutes, 180º right shoulder flexion (eight repetitions). Both tasks were performed with the elbow extended, wrist in neutral position and the palmar area of the hand toward the midline at the beginning and end of the movement. Results: A total of 11 subjects (8 men, 3 woman) were measured, whose mean of age was 24.7 years (SD = 4.22 years) and their average BMI was 22.64 Kg/m2 (SD = 2.29 Kg/m2). The mean of angular mobility collected by the smartphone was bigger in pitch axis for flexion (= 157.28°, SD= 12.35°) and abduction (= 151.71°, SD= 9.70°). With regard to acceleration, the highest peak mean value was shown in the Y motion axis during flexion (= 19.5°/s2, SD = 0.8°/s2) and abduction (= 19.4°/s2, SD = 0.8°/s2). Also, descriptive graphics of analytical tasks performed were obtained. Conclusions: This study shows how humerus contributes to upper-limb motion and it identified movement patterns. Therefore, it supports smartphone as a useful device to analyze upper-limb kinematics. Thanks to this study it´s possible to develop a simple application that facilitates the evaluation of the patient.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Semiempirical Modeling of Reset Transitions in Unipolar Resistive-Switching based Memristors

We have measured the transition process from the high to low resistivity states, i.e., the reset process of resistive switching based memristors based on Ni/HfO2/Si-n+ structures, and have also developed an analytical model for their electrical characteristics. When the characteristic curves are plotted in the current-voltage (I-V) domain a high variability is observed. In spite of that, when the same curves are plotted in the charge-flux domain (Q-phi), they can be described by a simple model containing only three parameters: the charge (Qrst) and the flux (rst) at the reset point, and an exponent, n, relating the charge and the flux before the reset transition. The three parameters can be easily extracted from the Q-phi plots. There is a strong correlation between these three parameters, the origin of which is still under study

Differences in Tridimensional Shoulder Kinematics between Asymptomatic Subjects and Subjects Suffering from Rotator Cuff Tears by Means of Inertial Sensors: A Cross-Sectional Study

Background: The aim of this study was to analyze differences in three-dimensional shoulder kinematics between asymptomatic subjects and patients who were diagnosed with rotator cuff tears. Methods: This cross-sectional study recruited 13 symptomatic subjects and 14 asymptomatic subjects. Data were obtained from three inertial sensors placed on the humerus, scapula and sternum. Kinematic data from the glenohumeral, scapulothoracic and thoracohumeral joints were also calculated. The participants performed shoulder abductions and flexions. The principal angles of movements and resultant vectors in each axis were studied. Results: The glenohumeral joint showed differences in abduction (p = 0.001) and flexion (p = 0.000), while differences in the scapulothoracic joint were only significant during flexion (p = 0.001). The asymptomatic group showed higher velocity values in all sensors for both movements, with the differences being significant (p < 0.007). Acceleration differences were found in the scapula during abduction (p = 0.001) and flexion (p = 0.014), as well as in the sternum only during shoulder abduction (p = 0.022). Conclusion: The results showed kinematic differences between the patients and asymptomatic subjects in terms of the mobility, velocity and acceleration variables, with lower values for the patients.This research was partially funded by Chartered of Physiotherapy of Andalusia (Spain) grant number 5369/16P/SG. Partial funding for open access charge: Universidad de Málag

Protein flexibility is key to cisplatin crosslinking in calmodulin

Chemical crosslinking in combination with Fourier transform ion cyclotron resonance mass spectrometry (FTICR MS) has significant potential for studying protein structures and proteinprotein interactions. Previously, cisplatin has been shown to be a crosslinker and crosslinks multiple methionine (Met) residues in apo-calmodulin (apo-CaM). However, the inter-residue distances obtained from nuclear magnetic resonance structures are inconsistent with the measured distance constraints by crosslinking. Met residues lie too far apart to be crosslinked by cisplatin. Here, by combining FTICR MS with a novel computational flexibility analysis, the flexible nature of the CaM structure is found to be key to cisplatin crosslinking in CaM. It is found that the side chains of Met residues can be brought together by flexible motions in both apo-CaM and calcium-bound CaM (Ca4-CaM). The possibility of cisplatin crosslinking Ca4-CaM is then confirmed by MS data. Therefore, flexibility analysis as a fast and low-cost computational method can be a useful tool for predicting crosslinking pairs in protein crosslinking analysis and facilitating MS data analysis. Finally, flexibility analysis also indicates that the crosslinking of platinum to pairs of Met residues will effectively close the nonpolar groove and thus will likely interfere with the binding of CaM to its protein targets, as was proved by comparing assays for cisplatin-modified/unmodified CaM binding to melittin. Collectively, these results suggest that cisplatin crosslinking of apo-CaM or Ca4-CaM can inhibit the ability of CaM to recognize its target proteins, which may have important implications for understanding the mechanism of tumor resistance to platinum anticancer drugs

Rigidity analysis of HIV-1 protease

We present a rigidity analysis on a large number of X-ray crystal structures of the enzyme HIV-1 protease using the 'pebble game' algorithm of the software FIRST. We find that although the rigidity profile remains similar across a comprehensive set of high resolution structures, the profile changes significantly in the presence of an inhibitor. Our study shows that the action of the inhibitors is to restrict the flexibility of the beta-hairpin flaps which allow access to the active site. The results are discussed in the context of full molecular dynamics simulations as well as data from NMR experiments.Comment: 4 pages, 3 figures. Conference proceedings for CMMP conference 2010 which was held at the University of Warwic

Comparative analysis of rigidity across protein families

We present a comparative study in which 'pebble game' rigidity analysis is applied to multiple protein crystal structures, for each of six different protein families. We find that the main-chain rigidity of a protein structure at a given hydrogen bond energy cutoff is quite sensitive to small structural variations, and conclude that the hydrogen bond constraints in rigidity analysis should be chosen so as to form and test specific hypotheses about the rigidity of a particular protein. Our comparative approach highlights two different characteristic patterns ('sudden' or 'gradual') for protein rigidity loss as constraints are removed, in line with recent results on the rigidity transitions of glassy networks

Ultrasonography Assessment Based on Muscle Thickness and Echo Intensity in Post-Polio Patients

There is no specific designed diagnostic test for post-poliomyelitis syndrome. The most important symptoms of this syndrome are new loss of muscle strength and more fatigue. Previous studies have investigated muscle ultrasound parameters to distinguish neuromuscular disease patients from healthy controls. The aim of this study was to investigate if muscle thickness and echo intensity measured by ultrasound can discriminate post-poliomyelitis syndrome patients from healthy controls. A total of 29 post-polio patients and 27 healthy controls participated in this cross-sectional study. Anthropometric measures, muscle thickness, echo intensity using B-mode ultrasound in rectus femoris and biceps brachii muscles, and muscle strength test data were collected. Muscle thickness in rectus femoris was significantly lower in post-poliomyelitis patients than in healthy controls, but not in biceps brachii. Echo intensity in rectus femoris and biceps brachii was higher in post-poliomyelitis syndrome patients than in healthy controls. Correlations were found between muscle thickness and strength in the upper and lower limbs. The results of the present study showed that muscle thickness in rectus femoris and echo intensity in rectus femoris and biceps brachii can discriminate post-poliomyelitis syndrome patients from healthy controls. A better assessment is possible because it can observe differences and relevant parameters in this clinical populationThe study has been co-funded under the OTRI research contract nº 806/87.5076 between the Universidad de Málaga and the Asociación Malagueña de Afectados Polio y Postpolio (AMAPyP). Partial funding for open access charge: Universidad de Málag

Diseño de un sistema de biofiltración para la remoción de estireno

El presente trabajo se enfocó en desarrollar un proceso para la eliminación del gas estireno, un contaminante orgánico generador de malos olores en el aire. Se construyó un sistema de biofiltración en el cual se emplearon bacterias del tipo Pseudomona aeruginosa y Escherichia coli adheridas a un soporte de piedra pómez. Se contaminó aire con estireno en concentraciones por encima del estándar norteamericano (TLV 40 ppm, ACGIH 2002), para simular una atmósfera laboral de alto riesgo a la salud. A fin de evaluar la eficiencia del sistema, se midieron directamente las concentraciones de estireno a la entrada y a la salida, utilizando un medidor de vapores orgánicos. Durante los primeros días se obtuvieron remociones por encima del 55%, para un promedio de 5 mediciones diarias, durante un periodo de 10 días. El sistema se fue estabilizando progresivamente durante la fase inicial, por lo que la remoción no fue la óptima. A partir del día 8 se alcanzaron remociones promedio por encima del 70% y remociones específicas superiores al 90%. El soporte de piedra pómez demostró ser una buena alternativa, facilitando la formación de una biopelícula; la rápida saturación de sus microporos permitió garantizar la baja adsorción del compuesto orgánico en el medio (piedra pómez + microorganismos), confirmando un auténtico proceso de biodegradación.This work was focused on developing an elimination process of styrene, an organic compound generating complex odors in air, through the design and construction of a biofiltration system, utilizing bacteria of the Pseudomona aeruginosa and Escherichia coli types stuck on a pumice stone support. Air was contaminated with styrene, in concentrations above the American Standard (TLV 40 ppm, ACGIH Worldwide, 2002), to simulate a hazardous work environment to the human health. To evaluate the efficiency of the system, the contaminated inlet air as well as the outlet flow were analyzed by taking direct styrene concentrations measurements with an organic vapor meter. Initially, the results obtained from the styrene degradation were above 55%, for a five-daily-sampling average during 10 days. This percentage was a consequence of the progressive stabilization process of the system within the first days, so the removal was low. However, average removals above 70% and punctual removals above 90% were reached after the eighth day. The pumice stone support demonstrated to be a good alternative to improve biofilm formation; the rapid micropore saturation guaranteed low adsorption of the organic compound and confirmed the elimination of styrene via biodegradation