Statistical correlation for the composite Boson

It is well known that the particles in a beam of Boson obeying Bose-Einstein statistics tend to cluster (bunching effect), while the particles in a degenerate beam of Fermion obeying Fermi-Dirac statistics expel each other (anti-bunching effect). Here we investigate, for the first time, the statistical correlation effect for the composite Boson, which is formed from a spin singlet entangled electron pair. By using nonequilibrium Green's function technique, we obtain a positive cross correlation for this kind of the composite Boson when the external voltage is smaller than the gap energy, which demonstrates that a spin singlet entangled electron pair looks like a composite Boson. In the larger voltage limit, the cross correlation becomes negative due to the contribution of the quasiparticles. At large voltages, the oscillation between Fermionic and Bosonic behavior of cross correlation is also observed in the strong coupling regime as one changes the position of the resonant levels. Our result can be easily tested in a three-terminal normal-superconductor-superconductor (N-S-S) hybrid mesoscopic system

Analysis of polyethylene wear in plain radiographs: The number of radiographs influences the results

Background and purpose Two-dimensional computerized radiographic techniques are frequently used to measure in vivo polyethylene (PE) wear after total hip arthroplasty (THA), and several variables in the clinical set-up may influence the amount of wear that is measured. We compared the repeatability and concurrent validity of linear PE wear on plain radiographs using the same software but a different number of radiographs

The Elite-Plus stem migrates more than the flanged Charnley stem: A clinical, radiographic, and radiostereometric analysis of 114 patients with an average of 7 years follow-up

Background and purpose The Charnley Elite-Plus stem was introduced in 1993 as a presumed improvement of the flanged Charnley stem. We started this study in 1996 to investigate the migratory pattern of the Elite-Plus stem. Patients and methods We followed 114 patients with osteoarthritis and a primary total hip replacement with the Elite-Plus stem. Mean age at the time of operation was 64 (50-76) years. The mean follow-up time was 6.5 (2-7) years. Radiographs were evaluated with respect to cementing technique, migration, and wear measured by radiostereometry (RSA). Results The stem survival was 98% (CI: 96-100) at 7 years and 92% (CI: 86-97) at 10 years. Mean migration of the femoral head was 0.35 mm (SD 0.3) medially, 0.51 mm (SD 0.6) distally, and 1.1 mm (SD 1.8) in the dorsal direction. Mean total point motion was 1.7 mm (SD 1.7). The migration of the stems stabilized after 5 years in the medial and dorsal directions, but continued to subside slightly. Migration along any of the axes was higher if the cementing technique was inferior. Interpretation Patients with a Charnley Elite-Plus stem and defects in the cement mantle or other signs of inferior implantation technique should be carefully monitored

The accuracy and precision of radiostereometric analysis in monitoring tibial plateau fractures

Background and purpose: The application of radiostereometric analysis (RSA) to monitor stability of tibial plateau fractures during healing is both limited and yet to be validated. We therefore evaluated the accuracy and precision of RSA in a tibial plateau fracture model. Methods: Combinations of 3, 6, and 9 markers in a lateral condyle fracture were evaluated with reference to 6 proximal tibial arrangements. Translation and rotation accuracy was assessed with displacement-controlled stages, while precision was assessed with dynamic double examinations. A comparison of error according to marker number and arrangement was completed with 2-way ANOVA models. Results: The results were improved using more tantalum markers in each segment. In the fracture fragment, marker scatter in all axes was achieved by a circumferential arrangement (medial, anterior, and lateral) of the tantalum markers above the fixation devices. Markers placed on either side of the tibial tuberosity and in the medial aspect of the fracture split represented the proximal tibial reference segment best. Using 6 markers with this distribution in each segment, the translation accuracy (root mean square error) was less than 37 μm in all axes. The precision (95% confidence interval) was less than ± 16 μm in all axes in vitro. Rotation, tested around the x-axis, had an accuracy of less than 0.123° and a precision of ± 0.024°. Interpretation: RSA is highly accurate and precise in the assessment of lateral tibial plateau fracture fragment movement. The validation of our center's RSA system provides evidence to support future clinical RSA fracture studies.Lucian B Solomon, Aaron W Stevenson, Stuart A Callary, Thomas R Sullivan, Donald W Howie, and Mellick J Chehad

Mutation Rate Switch inside Eurasian Mitochondrial Haplogroups: Impact of Selection and Consequences for Dating Settlement in Europe

R-lineage mitochondrial DNA represents over 90% of the European population and is significantly present all around the planet (North Africa, Asia, Oceania, and America). This lineage played a major role in migration “out of Africa” and colonization in Europe. In order to determine an accurate dating of the R lineage and its sublineages, we analyzed 1173 individuals and complete mtDNA sequences from Mitomap. This analysis revealed a new coalescence age for R at 54.500 years, as well as several limitations of standard dating methods, likely to lead to false interpretations. These findings highlight the association of a striking under-accumulation of synonymous mutations, an over-accumulation of non-synonymous mutations, and the phenotypic effect on haplogroup J. Consequently, haplogroup J is apparently not a Neolithic group but an older haplogroup (Paleolithic) that was subjected to an underestimated selective force. These findings also indicated an under-accumulation of synonymous and non-synonymous mutations localized on coding and non-coding (HVS1) sequences for haplogroup R0, which contains the major haplogroups H and V. These new dates are likely to impact the present colonization model for Europe and confirm the late glacial resettlement scenario

Accuracy of Model-based RSA Contour Reduction in a Typical Clinical Application

Marker-based roentgen stereophotogrammetric analysis (RSA) is an accurate method for measuring in vivo implant migration, which requires attachment of tantalum markers to the implant. Model-based RSA allows migration measurement without implant markers; digital pose estimation, which can be thought of as casting a shadow of a surface model of the implant into the stereoradiographs, is used instead. The number of surface models required in a given clinical study depends on the number of implanted sizes and design variations of prostheses. Contour selection can be used to limit pose estimation to areas of the prosthesis that do not vary with design, reducing the number of surface models required. The effect of contour reduction on the accuracy of the model-based method was investigated using three different contour selection schemes on tibial components in 24 patients at 3 and 6 month followup. The agreement interval (mean ± 2 standard deviations), which bounds the differences between the marker-based and model-based methods with contour reduction was smaller than −0.028 ± 0.254 mm. The data suggest that contour reduction does not result in unacceptable loss of model-based RSA accuracy, and that the model-based method can be used interchangeably with the marker-based method for measuring tibial component migration

Wear of a highly cross-linked polyethylene liner: a preliminary RSA study

Wear induced peri-prosthetic osteolysis and aseptic loosening remain the major contributing factors to failure of total hip arthroplasty. To reduce wear particles from acetabular liners, the process of polyethylene cross-linking has been modified. In this study, we examine the wear of Marathon™ acetabular liners using Radiostereometric Analysis. Thirty patients were enrolled in a prospective cohort study. Femoral head penetration was calculated for 25 patients at 6 months, 1 and 2 years postoperatively. The mean proximal head penetration was 0.067 mm at 6 months, 0.113 mm at 1 year and 0.120 mm at 2 years. The mean three-dimensional femoral head penetration was 0.240 mm at 6 months, 0.230 mm at 1 year and 0.232 mm at 2 years. For both parameters, there was no measurable wear between 1 and 2 years, and the mean annual linear wear was less than 0.06 mm/year, which is less than the suggested osteolysis threshold for polyethylene. All patients demonstrated a dramatic improvement in clinical scores. These results were comparable with other studies that used alternative techniques with conventional radiography to evaluate wear for Marathon™. Long-term studies using the RSA method are recommended to further quantify the clinical performance of this polyethylene liner.David Campbell, Graham Mercer, Kjell-Gunnar Nilsson, Vanessa Wells, John R. Field and Stuart A. Callar

Assessment of a failed (Painful?) total joint arthroplasty

Total joint arthroplasty (TJA) has provided, to patients with end stage major joint arthritis, reliable painless range of movement and functional recovery which can last for more than 15 years [1]. However, the majority of these artificial joints will eventually fail for various reasons, in a variety of failure patterns [2], and revision surgery becomes necessary. The lifetime of a TJA can be divided into three phases: the initial months during which the implant must become rigidly fixed (early stable phase) and the remainder of the implant's life, during which fixation may either be maintained (late stable phase) or lost (late unstable phase). An early unstable phase may also be seen, although infrequently these days, due mainly to errors of surgical technique. Orthopedic surgeons often face the question of how they can diagnose early loss of interface integrity, material structural failures, and how they can diagnose and treat other painful arthroplasty conditions. It should be realized that certain patterns of TJA failures can remain silent for a long period of time (Fig. 10.1). Regular follow-up examination of even painless and well-functioning TJAs should be organized at dedicated orthopedic centers in order to diagnose problems and failures as early as possible. © 2014 Springer-Verlag London. All rights are reserved