Neural Network Analysis of Bone Vibration Signals to Assesses Bone Density

Osteoporosis is a systemic disease, characterised by low bone mineral density (BMD) with a consequent increase in bone fragility. The most commonly used method to examine BMD is dual energy X-ray absorptiometry (DXA). However DXA cannot be used reliably in children less than 5 years old because of the limitations in the availability of required normative data. Vibration analysis is a well-established technique for analysing physical properties of materials and so it has the potential for assessing BMD. The overall purpose of this study was development and evaluation of low frequency vibration analysis as a tool to assess BMD in children. A novel portable computer-controlled system that suitably vibrated the bone, acquired, stored, displayed and analysed the resulting bone vibration responses was developed and its performance was investigated by comparing it with DXA-derived BMD values in children. 41 children aged between 7 and 15 years suspected of having abnormal BMD were enrolled. The ulna was chosen for all tests due to the ease with which it could be vibrated and responses measured. Frequency spectra of bone vibration responses were obtained using both impulse and continuous methods and these plus the participants’ clinical data were processed by a multilayer perceptron (MLP) artificial neural network. The correlation coefficient values between MLP outputs and DXA-derived BMD values were 0.79 and 0.86 for impulse and continuous vibration methods respectively. It was demonstrated that vibration analysis has potential for assessing fracture ris

Blood lactate disappearance dynamics in boys and men following exercise of similar and dissimilar peak-lactate concentrations

Characteristically, children recover faster than adults from various types of exercise. The purpose of the present study was to explain the children's faster recovery, in part, by addressing lactate (La) removal and comparing La disappearance dynamics in the two age groups following exercise of both similar and dissimilar peak blood-lactate concentration values ([La](pk))The subjects were 14 prepubertal boys and 12 men of similar peak oxygen consumption, normalized for body mass. All subjects performed 30 s supra-maximal cycling (Wingate anaerobic test [WAnT]). [La](pk) was 10.7 +/- 1.9 and 14.7 +/- 1.7 mmol(.)l(-1) for the boys and men, respectively (p < 0.001). The men were later retested in shortened versions of the WAnT so as to attain [La](pk) values (10.5 +/- 0.7 mmol(.)l(-1)) comparable to those achieved by the boys. [La](pk) lag time following the boys' standard WAnT was similar to that found in the men following the shortened WAnT (5.0 +/- 2.6 vs 5.7 +/- 1.3 min, respectively), but considerably shorter than that following the men's 30s-WAnT (7.6 +/- 2.1 min; p < 0.05). The La disappearance dynamics were closely matched between groups following the matched [La](pk) WAnTs. [La] half-life was similar under all conditions (ca. 20 min). It is concluded that prepubertal boys are characterized by a lower [La](pk) and a shorter time lag before reaching it, following 30-s supra-maximal cycling exercise. However, boys' La disappearance dynamics are not different from that of men

Three dimensional dynamics of laminated curved composite structures: A spectral-Tchebychev solution

Composite structures have been widely used in many diverse industries due to their high stiffness, high strength, and light-weight. Furthermore, since they exhibit directional material properties, it enables superior advantages in the design process such as achieving tailor-made characteristics. Since, these structures are subjected to dynamic excitations during operation, it is highly crucial to accurately and efficiently capture the dynamics of composite structures. This study presents a new spectral-Tchebychev (ST) solution to investigate the dynamic behavior of (curved) laminated composite structures. To derive the integral boundary value problem for each lamina, extended Hamilton principle is used. The strain energy is expressed using three-dimensional elasticity equations. To discretize the domain of the problem, Gauss-Lobatto sampling scheme is followed and the deflections (generalized coordinates) are expressed using triple expansion of Tchebychev polynomials. Then, the system matrices for each lamina is calculated using the derivative and the integral operations defined in the Tchebychev domain. To connect the individual laminae, compatibility equations are written. To incorporate the compatibility equations and to incorporate any type of boundary condition, projection matrices approach (that is based on singular value decomposition) is used. To validate the accuracy of the presented approach, two case studies (straight and curved laminated composite) are investigated. In each case the natural frequencies and the mode shapes are compared to those obtained from a commercial finite element (FE) software. The comparison indicates that presented three-dimensional spectral-Tchebychev solution technique enables the accurate and efficient prediction of the vibrational behavior of curved laminated composite structures

Reliability of peak-lactate, heart rate, and plasma volume following the Wingate test

Purpose: The 30-s Wingate Anaerobic Test (WAnT) has been used to assess anaerobic performance capacity and to evaluate physiological responses to supramaximal exercise. Blood lactate concentration ([La]) following supramaximal exercise is often used in the field and in the laboratory to assess the glycolytic contribution to exercise. Although the reliability of the performance in the WAnT has been established, this has not been the case with the WAnT's [La] response. Thus, the main purpose of this research was to study the test-retest reliability of peak [La] following the WAnT. Additionally, the test-retest reliability of the heart rate (HR) and plasma volume changes (Delta PV) response was also evaluated. Methods: Twenty-nine subjects (15 male, 14 female) of diverse training levels as well as physical characteristics (mean +/- SD: 23.3 +/- 7.0 yr, 62.5 +/- 12.0 kg, 170.8 +/- 9.7 cm, and 16.3 +/- 6.2% fat) performed two WAnTs within 1 wk. Capillary blood was sampled from a prewarmed fingertip at rest just before the WAnT and at 3, 5, 7, and 9 min following it. HR was also measured during these times. Results: Mean-power (MP) (+/-SE) in test 1 and test 2 was 8.4 +/- 0.2 and 8.3 +/- 0.2 W.kg(-1) body mass, respectively. Peak [La] was attained 5-7 min following the WAnTs and was nor significantly different between test 1 and test 2 (9.7 +/- 0.3 vs 9.8 +/- 0.3 mM, respectively). Peak HR occurred within 5 s post-WAnT and was not different between tests (170.8 +/- 2.2 and 171.3 +/- 2.2 beats.min(-1) in test 1 and test 2, respectively). Peak Delta PV was not different between tests (-12.0 +/- 3.4 and -11.1 +/- 3.2%, in rest 1 and test 2, respectively). The intraclass reliability coefficients for peak [La]. peak HR and Delta PV were 0.926, 0.941, and 0.878, respectively, whereas the corresponding value for MP was 0.982. Conclusions: We conclude that peak [La], peak HR, and Delta PV following me WAnT are reliable measures

Effects of swimming on erythrocyte rheological properties

Exercise and lactate usually change blood rheology but, effect of swimming on blood rheology is not clear. Blood lactate concentration increases after 400-meter freestyle swimming. In the hemorheological studies, determination of the erythrocyte deformability and aggregation facilitates the evaluation of rheological behaviours of the erythrocytes. The present study was performed to investigate the effects of acute swimming exercise on erythrocyte deformability and aggregation. Seventeen male university swimmers participated in the study. For 400-meter freestyle swimming, participants were asked to swim as fast as they could. Blood lactate concentration, erythrocyte lipid peroxidation and plasma protein oxidation levels, erythrocyte deformability and aggregation, and several haematological parameters were investigated after swimming and they were compared with pre-exercise values. Erythrocyte lipid peroxidation and plasma protein oxidation were unchanged with swimming. Blood lactate concentration increased after 400-meter swimming (p<0.001). Erythrocyte aggregation increased after acute swimming (p<0.01) while erythrocyte deformability was not change. There were no correlations between blood lactate and erythrocyte hemorheological properties before and after swimming.In conclusion, we found that erythrocyte aggregation increased after acute swimming. Further studies are needed to reveal the late effects of acute swimming and to elucidate the effect of swimming different distances on erythrocyte rheological properties

Comparison of leptin levels in serum and follicular fluid during the oestrous cycle in cows.

Leptin is mainly synthesised in white adipose tissue. Besides its effects on body weight and metabolic homeostasis, leptin also has effects on puberty, sexual Maturation and reproduction. In this study the relationship between leptin, IGF-1, oestradiol (E-2) and progesterone levels were investigated in serum and follicular fluid from cows. This Study included 72 healthy, Brown Swiss cows aged 45 years. Samples from the jugular vein and follicular fluids were collected. Phases of the oestrus cycle of cows were classified according to their serum progesterone levels (< 3.18 nmol/l, follicular phase and the others as luteal phase). Follicles were grouped as large (<8 mm) or small (< 8 mm). Leptin, IGF-1, oestradiol and progesterone levels were measured from serum and follicular fluid. Leptin concentrations were found to be significantly higher in luteal-phase follicular fluid of small follicles (P < 0.05). These were classified as atretic follicles. There was a positive correlation between serum and follicular fluid leptin levels ill the luteal phase. Serum leptin was found to have a positive correlation with follicular fluid progesterone level (P = 0.01) in the preovulatory follicles. The present Study shows that there is a relationship between the concentration of leptin in follicular fluid and atresia in small follicles