To what extent is joint and muscle mechanics predicted by musculoskeletal models sensitive to soft tissue artefacts?

Musculoskeletal models are widely used to estimate joint kinematics, intersegmental loads, and muscle and joint contact forces during movement. These estimates can be heavily affected by the soft tissue artefact (STA) when input positional data are obtained using stereophotogrammetry, but this aspect has not yet been fully characterised for muscle and joint forces. This study aims to assess the sensitivity to the STA of three open-source musculoskeletal models, implemented in OpenSim. A baseline dataset of marker trajectories was created for each model from experimental data of one healthy volunteer. Five hundred STA realizations were then statistically generated using a markerdependent model of the pelvis and lower limb artefact and added to the baseline data. The STA's impact on the musculoskeletal model estimates was finally quantified using a Monte Carlo analysis. The modelled STA distributions were in line with the literature. Observed output variations were comparable across the three models, and sensitivity to the STA was evident for most investigated quantities. Shape, magnitude and timing of the joint angle and moment time histories were not significantly affected throughout the entire gait cycle, whereas magnitude variations were observed for muscle and joint forces. Ranges of contact force variations differed between joints, with hip variations up to 1.8 times body weight observed. Variations of more than 30% were observed for some of the muscle forces. In conclusion, musculoskeletal simulations using stereophotogrammetry may be safely run when only interested in overall output patterns. Caution should be paid when more accurate estimated values are needed

Characterization of honeys from west and south Buenos Aires province, Argentina

Pollen analyses were carried out on 33 honey samples from Espinal, Monte de Llanuras y Mesetas and Pampeana phytogeographical Provinces, collected during the 2000-2001 period. Sample processing as well as qualitative and quantitative analyses were performed according to standard techniques. Sixty-seven morphological pollen types were identified. The association of Eucalyptus sp. (E. camaldulensis Dehnh., E. viminalis Labill.), Centaurea sp. (C. solstitialis L., C. calcitrapa L.) and Diplotaxis tenuifolia DC. characterized these honeys. Twelve samples were unifloral: six from Eucalyptus sp., five from Helianthus annuus L., and one from Brassicaceae. Asteraceae and Fabaceae were the most representative botanical families

A Melissopalynological map of the south and southwest of the Buenos Aires province, Argentina

El objetivo de este trabajo fue elaborar un mapa melitopalinológico del sur y sudoeste de la provincia de Buenos Aires, Argentina, con datos de análisis polínicos de 127 muestras de miel provenientes de las eco-regiones Pampa, Distrito del Caldén en el Espinal, y Monte de Llanuras y Mesetas, recolectadas en el período 1992-2002. Utilizando análisis de componentes principales y de cluster, los partidos se agruparon en cinco regiones: I (Tres Arroyos, San Cayetano, Coronel Pringles y Coronel Dorrego), II (Guaminí, Saavedra, Coronel Suárez y Adolfo Alsina), III (Coronel Rosales, Monte Hermoso, Bahía Blanca y Villarino), IV (Patagones y Tornquist) y V (Puán). En las Regiones I, III y IV el 80% de las muestras fueron monoflorales. La Región I se caracterizó por la presencia de un 50% de mieles de Helianthus annuus y de un 10% de mieles de trébol; la Región III por 60% de mieles de Eucalyptus sp.; y la Región IV por 30% de mieles de Diplotaxis tenuifolia. En las Regiones II y V el 50% de las mieles fueron monoflorales: la Región II se distinguió por la presencia de 50% de mieles de H. annuus y la Región V por 15% de mieles de Larrea divaricata y 15% de mieles de Vicia sp. Las mieles multiflorales de la Región V se destacaron por la presencia de pólen de Condalia microphylla. La mayor diversidad de tipos polínicos correspondió a las familias Fabaceae y Asteraceae. La asociación de Eucalyptus sp., Centaurea sp. y Diplotaxis tenuifolia caracterizó a las mieles de las cinco regiones. La variabilidad natural de las muestras de miel hace muy difícil definir límites precisos entre las diferentes regiones.The aim of this work was to produce a melissopalynological map of the south and southwest of the Buenos Aires Province, Argentina, using pollen analysis data pertaining to 127 honey samples from the Pampa, Espinal (the Calden District), and Monte de Llanuras y Mesetas ecoregions, collected over the period 1992-2002. Using principal components and hierarchical cluster analysis, the different districts were grouped into five regions: I (Tres Arroyos, San Cayetano, Coronel Pringles and Coronel Dorrego), II (Guaminí, Saavedra, Coronel Suárez and Adolfo Alsina), III (Coronel Rosales, Monte Hermoso, Bahía Blanca and Villarino), IV (Patagones and Tornquist), and V (Puán). In Regions I, III and IV, 80% of honey samples were monofloral: Region I was characterized by the presence of 50% Helianthus annuus honeys and 10% clover honeys, Region III by 65% Eucalyptus sp. honeys, and Region IV by 30% Diplotaxis tenuifolia honeys. In Regions II and V, 50% of honeys were monofloral. Region II was distinguished by the presence of 50% H. annuus honeys, and Region V by 15% Larrea divaricata and 15% Vicia sp. honeys. The multifloral honeys of Region V included samples containing Condalia microphylla pollen. The families Fabaceae and Asteraceae provided the greatest diversity of pollen types. The association of Eucalyptus sp., Centaurea sp., and Diplotaxis tenuifolia characterised the honeys from all five regions. The natural variability of honey samples renders it very difficult to define the boundaries between the different regions

Pollen and nectar sources used by honeybee colonies pollinating sunflower (Helianthus annuus) in the Colorado River Valley, Argentina

Pollen traps and beeswax foundations were set in order to study pollen and nectar sources used by honeybee colonies pollinating sunflower (Helianthus annuus L.) for the production of hybrid seed in the lower valley of the Colorado river in southern Argentina. Thirty-seven plant species in bloom were registered in the area surrounding the sunflower field. Most of them were scarcely represented. The honeybee maximum density recorded on the sunflower male-fertile line was 10.00 bees per 100 heads, while on the male-sterile line was 25.33 bees per 100 heads. Seven plant taxa were identified in the pollen loads and 26 in the honey samples. About 84% of the collected pollen came from three taxa: Centaurea solstitialis L., Eucalyptus camaldulensis Dehnh. and Cirsium vulgare (Savi) Airy -Shaw, and only 11% came from H. annuus. The taxa most gathered had high protein values, above 20%. The dominant and secondary pollen types in honey samples were Tamarix gallica L., E. camaldulensis, Brassicaceae and C. solstitialis. The results indicate that honeybees (Apis mellifera L.) foraged pollen and nectar mainly from the flora surrounding the sunflower field.Fuentes de polen y néctar utilizadas por colonias de Apis mellifera que polinizan girasol (Helianthus annuus) en el valle inferior del río Colorado, Argentina. Se colocaron trampas caza-polen y cuadros con cera estampada para estudiar las fuentes de polen y néctar utilizadas por colmenas que polinizan girasol para la producción de semilla híbrida en el valle inferior del río Colorado, Argentina. Treinta y siete especies en floración fueron registradas en cercanías al cultivo de girasol. La mayoría de ellas estuvieron escasamente representadas. La máxima densidad de abejas en la línea androfértil de girasol fue de 10,00 abejas por cada 100 inflorescencias, mientras que en la línea androestéril fue de 25,33 abejas por cada 100 inflorescencias. En las cargas polínicas se identificaron siete taxa, y 26 en las muestras de miel. El 84% en peso del polen recolectado correspondió a tres taxa: Centaurea solstitialis L., Eucalyptus camaldulensis Dehnh. y Cirsium vulgare (Savi) Airy -Shaw y sólo el 11% provino de H. annuus. Los taxa más cosecha-dos tuvieron valores de proteína altos, superiores a 20%. Los tipos polínicos dominantes y secun-darios en las muestras de miel fueron Tamarix gallica L. y E. camaldulensis, Brassicaceae y C. solstitialis. Los resultados indican que las abejas (Apis mellifera L.) recolectaron polen y néctar principalmente de la flora circundante al cultivo de girasol

Personalised 3D knee compliance from clinically viable knee laxity measurements: A proof of concept ex vivo experiment.

Personalised information of knee mechanics is increasingly used for guiding knee reconstruction surgery. We explored use of uniaxial knee laxity tests mimicking Lachman and Pivot-shift tests for quantifying 3D knee compliance in healthy and injured knees. Two healthy knee specimens (males, 60 and 88 years of age) were tested. Six-degree-of-freedom tibiofemoral displacements were applied to each specimen at 5 intermediate angles between 0° and 90° knee flexion. The force response was recorded. Six-degree-of-freedom and uniaxial tests were repeated after sequential resection of the anterior cruciate, posterior cruciate and lateral collateral ligament. 3D knee compliance (C6DOF) was calculated using the six-degrees-of-freedom measurements for both the healthy and ligament-deficient knees and validated using a leave-one-out cross-validation. 3D knee compliance (CCT) was also calculated using uniaxial measurements for Lachman and Pivot-shift tests both conjointly and separately. C6DOF and CCT matrices were compared component-by-component and using principal axes decomposition. Bland-Altman plots, median and 40-60th percentile range were used as measurements of bias and dispersion. The error on tibiofemoral displacements predicted using C6DOF was < 9.6% for every loading direction and after release of each ligament. Overall, there was good agreement between C6DOF and CCT components for both the component-by-component and principal component comparison. The dispersion of principal components (compliance coefficients, positions and pitches) based on both uniaxial tests was lower than that based on single uniaxial tests. Uniaxial tests may provide personalised information of 3D knee compliance

Impact of thixotropy on flow patterns induced in a stirred tank : numerical and experimental studies

Agitation of a thixotropic shear-thinning fluid exhibiting a yield stress is investigated both experimentally and via simulations. Steady-state experiments are conducted at three impeller rotation rates (1, 2 and 8 s−1) for a tank stirred with an axial-impeller and flow-field measurements are made using particle image velocimetry (PIV) measurements. Threedimensional numerical simulations are also performed using the commercial CFD code ANSYS CFX10.0. The viscosity of the suspension is determined experimentally and is modelled using two shear-dependant laws, one of which takes into account the flow instabilities of such fluids at low shear rates. At the highest impeller speed, the flow exhibits the familiar outward pumping action associated with axial-flow impellers. However, as the impeller speed decreases, a cavern is formed around the impeller, the flow generated in the vicinity of the agitator reorganizes and its pumping capacity vanishes. An unusual flow pattern, where the radial velocity dominates, is observed experimentally at the lowest stirring speed. It is found to result from wall slip effects. Using blades with rough surfaces prevents this peculiar behaviour and mainly resolves the discrepancies between the experimental and computational results

Influenza vaccine effectiveness for the elderly: a cohort study involving General Practitioners from Abruzzo, Italy

Introduction. In all Italian regions influenza vaccine is routinely administered to the elderly population. However, vaccination impact has been rarely evaluated because of the high costs of conventional cohort investigations. A promising low-cost alter- native approach uses administrative discharge data to derive vaccine effectiveness indicators (hospitalizations and/or deaths) and involves General Practitioners (GPs) to document the exposure. We conducted a cohort analysis using such approach to assess influenza vaccine effectiveness and to investigate the feasibility and validity of that methodology for routine vaccine evaluation. Methods. During October 2006, all GPs from two Local Health Units (LHUs) were requested to indicate immunization status of all their patients in a specific form containing patient?s demo- graphic records. Immunization status information were also collected from Prevention Departments. Main outcomes were hospitalizations for influenza and/or pneumonia. Analyses were based upon random-effect logistic regression. Results. Of a total of 414 GPs assisting 103,162 elderly, 116 GPs (28%) provided data on 32,457 individuals (31.5%). The sample was representative and had an overall 66.2% vaccina- tion rate. During the first semester 2007, the hospitalization rate was low in the sample, with only 7 elderly patients admitted for influenza and 135 for pneumonia. At either bivariate or multi- variate analysis, vaccination did not significantly reduce the risk of in-hospital death, influenza or pneumonia admission. Discussion. The study had minimal costs, recruited a large and representative sample size, and had no evidence of a substantial selection bias. Administrative and GP?s data may be successively pooled to provide routine assessment of vaccination effectiveness