New quantitative radiographic parameters for vertical and horizontal instability in acromioclavicular joint dislocations.

PURPOSE The aim of this study was to identify the most accurate and reliable quantitative radiographic parameters for assessing vertical and horizontal instability in different Rockwood grades of acromioclavicular joint (ACJ) separations. Furthermore, the effect of projectional variation on these parameters was investigated in obtaining lateral Alexander view radiographs. METHODS A Sawbone model of a scapula with clavicle was mounted on a holding device, and acromioclavicular dislocations as per the Rockwood classification system were simulated with the addition of horizontal posterior displacement. Projectional variations for each injury type were performed by tilting/rotating the Sawbone construct in the coronal, sagittal or axial plane. Radiographic imaging in the form of an anterior-posterior Zanca view and a lateral Alexander view were taken for each injury type and each projectional variation. Five newly defined radiographic parameters for assessing horizontal and vertical displacement as well as commonly used coracoclavicular distance view were measured. Reliability, validity and the effect of projectional variation were investigated for these radiographic measurements. RESULTS All radiographic parameters showed excellent intra- and interobserver reliability. The validity was excellent for the acromial centre line to dorsal clavicle (AC-DC) in vertical displacement and for the glenoid centre line to posterior clavicle (GC-PC) in horizontal displacement, whilst the remaining measurements showed moderate validity. For AC-DC and GC-PC, convergent validity expressed strong correlation to the effective distance and discriminant validity demonstrated its ability to differentiate between various grades of ACJ dislocations. The effect of projectional variation increased with the degree of deviation and was maximal (3 mm) for AC-DC in 20° anteverted malpositioning and for GC-PC in 20° retroverted malpositioning. CONCLUSIONS AC-DC and the GC-PC are two novel quantitative radiographic parameters of vertical and horizontal instability in ACJ dislocations that demonstrate excellent reliability and validity with reasonable inertness to malpositioning. The use of AC-DC for assessing vertical displacement and GC-PC for assessing horizontal displacement in a single Alexander view is recommended to guide the appropriate management of ACJ dislocations. A better appreciation of the degree of horizontal instability, especially in lower Rockwood grades (II, III) of ACJ dislocations, may improve management of these controversial injuries

Experimental delayed-choice entanglement swapping

Motivated by the question, which kind of physical interactions and processes are needed for the production of quantum entanglement, Peres has put forward the radical idea of delayed-choice entanglement swapping. There, entanglement can be "produced a posteriori, after the entangled particles have been measured and may no longer exist". In this work we report the first realization of Peres' gedanken experiment. Using four photons, we can actively delay the choice of measurement-implemented via a high-speed tunable bipartite state analyzer and a quantum random number generator-on two of the photons into the time-like future of the registration of the other two photons. This effectively projects the two already registered photons onto one definite of two mutually exclusive quantum states in which either the photons are entangled (quantum correlations) or separable (classical correlations). This can also be viewed as "quantum steering into the past"

Space-QUEST: Experiments with quantum entanglement in space

The European Space Agency (ESA) has supported a range of studies in the field of quantum physics and quantum information science in space for several years, and consequently we have submitted the mission proposal Space-QUEST (Quantum Entanglement for Space Experiments) to the European Life and Physical Sciences in Space Program. We propose to perform space-to-ground quantum communication tests from the International Space Station (ISS). We present the proposed experiments in space as well as the design of a space based quantum communication payload.Comment: 4 pages, 1 figure, accepted for the 59th International Astronautical Congress (IAC) 200

Space QUEST mission proposal: experimentally testing decoherence due to gravity

Models of quantum systems on curved space-times lack sufficient experimental verification. Some speculative theories suggest that quantum properties, such as entanglement, may exhibit entirely different behavior to purely classical systems. By measuring this effect or lack thereof, we can test the hypotheses behind several such models. For instance, as predicted by Ralph and coworkers [T C Ralph, G J Milburn, and T Downes, Phys. Rev. A, 79(2):22121, 2009, T C Ralph and J Pienaar, New Journal of Physics, 16(8):85008, 2014], a bipartite entangled system could decohere if each particle traversed through a different gravitational field gradient. We propose to study this effect in a ground to space uplink scenario. We extend the above theoretical predictions of Ralph and coworkers and discuss the scientific consequences of detecting/failing to detect the predicted gravitational decoherence. We present a detailed mission design of the European Space Agency's (ESA) Space QUEST (Space - Quantum Entanglement Space Test) mission, and study the feasibility of the mission schema.Comment: 18 pages, 13 figures, included radiation damage to detectors in appendi

Effect of diagnostic occlusion and surgery in acquired trochlear nerve palsy

Bei zyklovertikalen Schielformen kann sich der fusionale Vergenztonus adaptiv verändern. Eine monokulare Okklusion unterbricht die binokulare Sensorik und hebt die Notwendigkeit fusionaler Vergenz auf, wodurch das genuine Profil der zugrunde liegenden Störung hervortreten soll, was diagnostisch und dosimetrisch relevant ist. Um den Effekt der diagnostischen Okklusion auf das Motilitätsmuster bei einseitiger Trochlearisparese zu untersuchen, wurden aus dem operativen Krankengut der Universitätsaugenklinik für Schielbehandlung und Neuroophthalmologie Gießen 51 Patienten im Alter von sechs bis 78 Jahren anhand der Operationsdokumentationen ausgesucht. Bei diesen Patienten wurden vor und unmittelbar nach einer dreitägigen diagnostischen Okklusion die subjektiv lokalisierten Schielwinkel an der Tangentenskala nach Harms in 2,5 m Distanz mit einem Dunkelrotglas vor dem nichtparetischen Auge gemessen. Statistisch ausgewertet wurden unter anderem die Vertikal- und Zyklodeviation in Primärposition, bei 25° Abduktion des nichtparetischen Auges (in Adduktion des paretischen Auges) und bei 25° Abblick. Unter Okklusion zeigte sich eine statistisch signifikante Zunahme der Zyklodeviation, die mit 1° im Median gering war, bei großer Variabilität. Die Abnahme der Vertikaldeviation war lediglich im Abblick signifikant. Die Auswertung zeigt, dass eine diagnostische Okklusion bei erworbener Trochlearisparese oft, aber nicht regelmäßig zu einer Abnahme der Vertikal- und einer Zunahme der Exzyklodeviation führt. Zur operativen Behandlung der Trochlearisparese hat sich bisher keine einheitliche Vorgehensweise durchgesetzt. In dieser Studie wurden daher die Effekte der alleinigen Rücklagerung des M. obliquus inferior (OIR), der alleinigen Faltung des M. obliquus superior (OSF) und einer Kombination dieser beiden Operationsverfahren (KOP) untersucht, indem die Schielwinkel der unterschiedlich operierten Patienten prä- und drei Monate postoperativ an der Tangentenskala nach Harms gemessen und statistisch ausgewertet wurden. Hierzu wurden weitere 19 Patienten aus dem Zentrum für Augenheilkunde des Universitätsklinikums Essen rekrutiert, die nach denselben Kriterien ausgesucht worden waren und eine OSF erhalten hatten. Das Kopfneigephänomen und die Zyklovertikaldeviationen wurden durch die KOP stärker reduziert als durch die OIR oder die OSF allein. Besonders im unteren Blickbereich hinterließen die OIR und die OSF größere Restschielwinkel als die KOP. Der stärkere Effekt der KOP in den horizontalen und unteren Blickrichtungen ging im Aufblick mit einem Brown-Syndrom einher.The fundamental motility pattern of cyclovertical strabismus can be modulated by adaption due to the compensatory fusional vergence tonus. Monocular occlusion interrupts binocular vision and eliminates the need of fusional vergence. So, diagnostic occlusion may be useful to isolate the genuine profile of the fundamental disorder as an important finding regarding both the diagnostics of the palsy and the dosage of surgery. In this study, the effect of diagnostic occlusion on the motility pattern of unilateral acquired trochlear nerve palsy was investigated. All together there were 51 patients aged 6 to 78 years with unilateral acquired trochlear nerve palsy who were examined before and after three days of diagnostic occlusion. The subjective squint angles localized with a dark red glass in front of the non-paretic eye were measured at a distance of 2.5 m using Harms’ tangent scale. Vertical and torsional angles in primary position, in 25° abduction of the non paretic eye (adduction of the paretic eye), and in 25° down gaze were compared. Diagnostic occlusion caused an increase of excyclodeviation which was statistically significant but small, with the median at 1° and large variability. In down gaze, there was a significant decrease of the hyperdeviation. Concluding the diagnostic occlusion often but not regularly causes a decrease of the vertical and an increase of the excyclodeviation in patients with acquired trochlear nerve palsy. For surgical treatment of unilateral acquired trochlear nerve palsy there are different surgical treatments recommended. In this study, recession of the inferior oblique muscle (OIR), tucking or advancement of the superior oblique tendon (OSF) and the combination of both procedures (KOP) were investigated regarding their effect on cyclo-vertical deviation and head-tilt phenomenon. Squint angles and fields of binocular fusion were measured at a distance of 2.5 m using Harms’ tangent scale before and three months after surgery. For investigation of the effect of pure OSF, data of additional 19 patients were recruited in the Department of Ophthalmology, University of Essen. Head-tilt phenomenon and cyclo-vertical deviation were more effectively reduced by KOP than by pure IOR or OSF. Especially in downgaze residual squint angles were larger after pure OIR and OSF than after KOP.but therefor a Brown-Syndrome often appeared at upgaze. The higher beneficial effect of KOP in the horizontal and downgaze directions came along with the distracting side effect of Brown’s syndrome in upgaze

Intra-articular horizontal dislocation of the patella: a rare injury and review of the literature.

Acute traumatic intra-articular dislocation of the patella is not a common presentation in orthopaedic practice; less frequently observed than extra-articular dislocation of the patella. In some of these cases, closed reduction is not possible and an open reduction in the operating theatre must be performed. In this case report, we present an elderly patient with an intra-articular horizontal dislocation of the patella without any other bony or ligamentous lesions seen in a postreduction MRI. We conducted a literature review looking at intra-articular patella dislocations, identifying 64 published studies (articles, case reports and papers). The following sources of data were searched until December 2017: PubMed, OVID, Google Scholar, Scopus, using the search strategy of (intra-articular dislocation of patella, horizontal patellar dislocation) with no limitation on the year or language of publication. The patient presented in this case report was managed with a closed reduction under general anaesthesia, without the need of any surgical intervention. As proposed in the literature, the hypothesis of an intra-articular entrapment of the patella due to the trapped osteophytes of the superior pole of the patella into the intercondylar notch was thought to be the cause of intra-articular dislocation in this elderly patient