Load displacement behavior of the human Lumbo-sacral joint

The three-dimensional load displacement behavior of nine fresh adult L5-S1 spine motion segments was studied. Static test forces up to 160 N in anterior, posterior, and lateral shear, test forces up to 320 N in compression, and test moments up to 15.7 Nm in flexion, extension, lateral bending, and torsion were used. The six displacements of the center of the inferior L5 endplate were measured 15 and 60 s after the load was applied. Specimens were then retested after posterior element excision. The results show that at the maximum test force, intact specimen mean (sd) displacements ranged from 1.65 mm (0.63 mm) in lateral shear to 2.21 mm (0.87 mm) in posterior shear. Posterior element excision resulted in an average 1.66-fold increase in shear translations. At the maximum moment, rotations ranged from 3.38° (1.03°) in torsion to 7.19° (1.77°) in flexion. Posterior element excision resulted in an average 2.09-fold increase in bending rotations and a 2.74-fold increase in the average torsional rotation. In general, these L5-S1 joints were stiffer than more cranial lumbar segments in flexion, extension, and lateral bending and were less stiff in torsion tests.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/50380/1/1100050404_ftp.pd

Unique anisotropic optical properties of a highly stable metal–organic framework based on trinuclear iron(III) secondary building units linked by tetracarboxylic linkers with an anthracene core

A highly stable metal–organic framework, [{Fe3(ACTBA)2}X·6DEF]n (1; X = monoanion), based on trinuclear iron(III) secondary building units connected by tetracarboxylates with an anthracene core, 2,6,9,10-tetrakis(p-carboxylatophenyl)anthracene (ACTBA), is reported. Depending on the direction of light polarisation, crystals of 1 exhibit anisotropic optical properties with birefringence Δn = 0.3 (λ = 590 nm)

7th SOSORT consensus paper: conservative treatment of idiopathic & Scheuermann's kyphosis

<p>Abstract</p> <p/> <p>Thoracic hyperkyphosis is a frequent problem and can impact greatly on patient's quality of life during adolescence. This condition can be idiopathic or secondary to Scheuermann disease, a disease disturbing vertebral growth. To date, there is no sound scientific data available on the management of this condition. Some studies discuss the effects of bracing, however no guidelines, protocols or indication's of treatment for this condition were found. The aim of this paper was to develop and verify the consensus on managing thoracic hyperkyphosis patients treated with braces and/or physiotherapy.</p> <p>Methods</p> <p>The Delphi process was utilised in four steps gradually modified according to the results of a set of recommendations: we involved the SOSORT Board twice, then all SOSORT members twice, with a Pre-Meeting Questionnaire (PMQ), and during a Consensus Session at the SOSORT Lyon Meeting with a Meeting Questionnaire (MQ).</p> <p>Results</p> <p>There was an unanimous agreement on the general efficacy of bracing and physiotherapy for this condition. Most experts suggested the use of 4-5 point bracing systems, however there was some controversy with regards to physiotherapeutic aims and modalities.</p> <p>Conclusion</p> <p>The SOSORT panel of experts suggest the use of rigid braces and physiotherapy to correct thoracic hyperkyphosis during adolescence. The evaluation of specific braces and physiotherapy techniques has been recommended.</p

Clinical potential for noninvasive prenatal diagnosis through detection of fetal cells in maternal blood

Summary Fetal cells circulate in maternal blood and are considered a suitable means by which to detect fetal genetic and chromosomal abnormalities. This approach has the advantage of being noninvasive. Since the early 1990s, nucleated erythrocytes (NRBCs) have been considered good target cells for a number of techniques, including fluorescence-activated cell sorting and magnetic cell sorting, using antibodies such as anti-transferrin receptor and anti-?-hemoglobin antibodies, followed by analysis with fluorescence in situ hybridization or polymerase chain reaction. In the late 1990s, the National Institute of Child Health and Human Development Fetal Cell Isolation Study assessed the reliability of noninvasive prenatal diagnosis of fetal aneuploidy using NRBCs isolated from maternal circulation. This study revealed the limitations of NRBC separation using antibodies specific for NRBC antigens. A more recent study has demonstrated the efficiency and success of recovery of NRBCs using a galactose-specific lectin, based on the observation that erythroid precursor cells have a large quantity of galactose molecules on their cell surface. Thus, recent advances in this field enhance the feasibility of this diagnostic method. This review article focuses on various methods of detection of fetal cells within the maternal circulation, as well as the status of previous and current studies and the prospective view for noninvasive prenatal diagnosis using fetal cells from the maternal circulation

The spine in Paget’s disease

Paget’s disease (PD) is a chronic metabolically active bone disease, characterized by a disturbance in bone modelling and remodelling due to an increase in osteoblastic and osteoclastic activity. The vertebra is the second most commonly affected site. This article reviews the various spinal pathomechanisms and osseous dynamics involved in producing the varied imaging appearances and their clinical relevance. Advanced imaging of osseous, articular and bone marrow manifestations of PD in all the vertebral components are presented. Pagetic changes often result in clinical symptoms including back pain, spinal stenosis and neural dysfunction. Various pathological complications due to PD involvement result in these clinical symptoms. Recognition of the imaging manifestations of spinal PD and the potential complications that cause the clinical symptoms enables accurate assessment of patients prior to appropriate management

Examination and optimization of lateral dynamics of single-track vehicles - particularly bicycles - with coupled rear seering

In dieser Arbeit wird ein Fahrradmodell mit mitlenkender Hinterachse aufgestellt und untersucht, wobei die Mitlenkung der Hinterachse an die Lenkung der Vorderachse gekoppelt ist. Es basiert auf dem Fahrradmodell des benchmark bicycle [Schwab et al. 2007], das ein gewöhnliches Fahrrad darstellt. Motivation ist eine Erhöhung der Selbststabilität und eine Verringerung der Gierwinkel in alltäglichen Fahrsituationen und in der Geradeausfahrt. Die Herleitung der Bewegungsdifferentialgleichungen erfolgt nach LAGRANGE, wobei das in [Basu-Mandal 2007] genutzte Schema verwendet wird. Zuerst erfolgt die Herleitung des Modells des gewöhnlichen Fahrrads, darauf aufbauend erfolgt die Herleitung des Modells mit mitlenkender Hinterachse. Das Fahrradmodell besitzt – im Falle des gewöhnlichen Fahrrads – neun Freiheitsgrade, von denen sieben voneinander unabhängig sind und zwei – durch holonom-skleronome Zwangsbedingungen – abhängig sind. Vier nicht-holonome Zwangsbedingungen reduzieren die unabhängigen Koordinaten in der ersten und der zweiten zeitlichen Ableitung auf drei. Im Falle des Modells mit mitlenkender Hinterachse liegen zehn Freiheitsgrade und drei holonom-skleronome Zwangsbedingungen vor. Wiederum sind also sieben Freiheitsgrade unabhängig voneinander und wieder reduzieren vier nicht-holonome Zwangsbedingungen die Zahl der unabhängigen Koordinaten in der ersten und der zweiten zeitlichen Ableitung auf drei. Die Herleitung der LAGRANGE-Gleichungen und der Zwangsbedingungen erfolgt nichtlinear unter Zuhilfenahme von Maple. Mittels mehrdimensionaler TAYLOR-Entwicklungen werden die sehr langen Ausdrücke linearisiert und so gekürzt. Aus den genannten Gleichungen resultieren zwei Bewegungsdifferentialgleichungen, die die Bewegungen des Fahrrads in der Lenkung und der seitlichen Neigung beschreiben. Die Bewegungsdifferentialgleichungen werden für 33 Parameterkombinationen des Mitlenkfaktors – also des Verhältnisses zwischen dem hinteren und dem vorderen Lenkwinkel – und des hinteren Lenkachswinkels aufgestellt. Eine Validierung erfolgt mittels eines zweiten, numerischen Modells, das in der Softwareumgebung Simpack erstellt wurde. Die Stabilitätsdiagramme der Parameterkombinationen für variable Geschwindigkeiten werden aufgestellt. Fünf verschiedene alltägliche Fahrmanöver werden im Zeitbereich bei drei verschiedenen Geschwindigkeiten untersucht, wobei der Neigungswinkel, der Lenkwinkel und der Gierwinkel jeweils Untersuchungsgegenstand sind. Eines der fünf Fahrmanöver stellt eine Störung der Geradeausfahrt dar, der ein besonderes Augenmerk gilt. Die Stabilitätsdiagramme und die Winkelverläufe der Fahrmanöver werden untersucht und bewertet, woraufhin günstige Parameterkombinationen identifiziert werden.In this thesis, a model of a bicycle with additional rear steering is derived and examined. The rear steering angle is coupled with the front steering angle. The model is based on the benchmark bicycle [Schwab et al. 2007] which describes a regular bicycle. Main motivation is an increase of self-stability and a reduction of yaw angle in everyday driving maneuvers and in straight-line driving. The equations of motion are derived with the aid of the LAGRANGE function by using the scheme presented in [Basu-Mandal 2007]. At first, the model of the regular bicycle is derived. On this basis, the model of the bicycle with coupled rear steering is derived. In the first case, the model has nine degrees of freedom, of which seven are independent. Two degrees of freedom are dependent due to two holonomic-scleronomic constraints. Four non-holonomic constraints reduce the number of independent coordinates in the first and the second time derivative from seven to three. The model with coupled rear steering has ten degrees of freedom, of which seven are independent. Three degrees of freedom are dependent due to three holonomic-scleronomic constraints. Again, four non-holonomic constraints reduce the number of independent coordinates in the first and the second time derivative from seven to three. The derivation of the LAGRANGE equations and the constraints is completely non-linear by the aid of the software environment Maple. By multidimensional TAYLOR series, the very long expressions are linearized and shortened. Two equations of motion result describing the steer angle and the roll angle. The equations of motion are used to examine 33 parameter combinations of the ratio between rear and front steering angle – called Mitlenkfaktor – and the rear fork pitch angle. Validations are carried out by a second simulation model, which is programmed in multibody-simulation environment Simpack. Stability diagrams, in which the forward speed is shown on the abscissa and the eigenvalues of the differential equation system are shown on the ordinate, are given for the different parameter combinations. Five everyday driving maneuvers are simulated in the time domain for three different forward speeds. The roll angle, the steer angle and the yaw angle are examined. One of the five maneuvers simulates a disturbance of straight-line driving, which is considered as particularly important. Stability diagrams and the three mentioned angles over time are examined and evaluated to identify parameter combinations with beneficial influence on driving behavior