Post-processing of real-time quantum event measurements for an optimal bandwidth.

Single electron tunneling and its transport statistics have been studied for some time using high precision charge detectors. However, this type of detection requires advanced lithography, optimized material systems and low temperatures (mK). A promising alternative, recently demonstrated, is to exploit an optical transition that is turned on or off when a tunnel event occurs. High bandwidths should be achievable with this approach, although this has not been adequately investigated so far. We have studied low temperature resonance fluorescence from a self-assembled quantum dot embedded in a diode structure. We detect single photons from the dot in real time and evaluate the recorded data only after the experiment, using post-processing to obtain the random telegraph signal of the electron transport. This is a significant difference from commonly used charge detectors and allows us to determine the optimal time resolution for analyzing our data. We show how this post-processing affects both the determination of tunneling rates using waiting-time distributions and statistical analysis using full-counting statistics. We also demonstrate, as an example, that we can analyze our data with bandwidths as high as 175 kHz. Using a simple model, we discuss the limiting factors for achieving the optimal bandwidth and propose how a time resolution of more than 1 MHz could be achieved.

[Braking capacity after hip arthroplasty - effect of prosthesis design and preoperative status]. / Bremsfähigkeit von Patienten nach endoprothetischer Versorgung des Hüftgelenks - Einfluss von Prothesendesign und präoperativem Status.

BACKGROUND: Driving a car is an important everyday activity. However, the patients' desire to resume driving at an early stage after hip arthroplasty is often faced by the uncertainty about their driving ability. Only little evidence is available to support the clinical decision-making with regard to driving competence after conventional total hip arthroplasty (THA). However, there is no proof that the results observed after THA can be transferred to hip resurfacing arthroplasty (HRA) patients. Due to physiological advantages, i.e., patient age and activity, as well as the special biomechanical implant characteristics, HRA patients could be expected to achieve normal braking capacity at an earlier stage in the rehabilitation process than THA patients. This could be achieved by an accelerated postoperative recovery or could depend on the preoperative vantage point concerning the patients' braking capacity. PATIENTS AND METHODS: To verify this hypothesis HRA and THA patients were compared to healthy subjects concerning their ability to perform an emergency braking manoeuvre in a car simulator before surgery, and at 6 weeks and 3 months after operation. Furthermore, postoperative recovery rates were compared between the two groups of patients. In addition, correlations between pre- and postoperative braking capacity were tested. Reaction time, movement time and force-time integral on the brake pedal were analysed. RESULTS: Except for a deficient preoperative force-time integral, no significant differences were detected in HRA patients compared to healthy controls. In contrast THA patients required, pre- as well as postoperatively, a longer movement time and exhibited a smaller force-time integral. The two patient groups did not show any significant difference in recovery rates of movement time and force-time integral. However, considering the two patient groups as a whole, a significant correlation was detected between existing pre- and postoperative deficits. CONCLUSION: In conclusion, it can be confirmed that HRA patients resume normal braking capacity at an earlier stage in their rehabilitation process than THA patients. Patients recommended for HRA recover braking capacity at the latest six weeks after surgery. This capacity clearly depends on the better preoperative status of the HRA patients and is not determined by a faster recovery rate. General patient-related advantages as well as biomechanical aspects of HRA have thus no influence on the recovery rates of braking capacity during the first three months after surgery. Due to the increasing outpatient rehabilitation regime after HRA, further studies are necessary to detect the turning point after surgical impairment within the first six weeks after surgery. Concerning the THA patients we recommend a longer safety distance when driving a car for up to three months after the operation. However, patients, especially those assigned to THA, should be made aware of their most likely already existing preoperative deficit. For clinical practice a rough estimation of postoperative braking capacity seems to be possible based on group assignment (HRA/THA). Nevertheless, deviators cannot be detected by this group classification. As driving simulator systems usually are not available in hospitals, a more accurate prognosis, i.e., based on established clinical scores, would be helpful.

Finite helical axes of motion are a useful tool to describe the three-dimensional in vitro kinematics of the intact, injured and stabilised spine.

The finite helical-axes method can be used to describe the three-dimensional in vitro kinematics of the spine. However, this method still suffers from large stochastic calculation errors and poorly conceived visualisation techniques. The aim of the present study, therefore, was to improve the currently used finite helical axes description, by use of a less error-prone calculation algorithm and a new visualisation technique, and to apply this improved method to the study of the three-dimensional in vitro kinematics of the spine. Three-dimensional, continuous motion data of spinal motion segments were used to calculate the position and orientation of the finite helical axes (FHAs). The axes were then projected on plane antero-posterior, lateral and axial radiographs in order to depict the relation to the anatomy of each individual specimen. A hinge joint was used to estimate the measurement error of data collection and axes calculation. In an exemplary in vitro experiment, this method was used to demonstrate the ability of a prosthetic disc nucleus to restore the three-dimensional motion pattern of lumbar motion segments. In the validation experiment with the hinge joint, the calculated FHAs were lying within +/-2.5 mm of the actual joint axis and were inclined relative to this axis at up to +/-1.5 degrees . In the exemplary in vitro experiment, the position and orientation of the FHAs of the intact specimens were subject to large inter-individual differences in all loading directions. Nucleotomy of the lumbar segments caused the axes to spread out, indicating complex coupled motions. The implantation of the prosthetic disc nucleus, for the most part, more than reversed this effect: the axes became oriented almost parallel to each other. The experiments showed that the present improved description of finite helical axes is a valid and useful tool to characterise the three-dimensional in vitro kinematics of the intact, injured and stabilised spine. The main advantage of this new method is the comprehensive visualisation of joint function with respect to the individual anatomy.

Anterior cruciate ligament rupture translates the axes of motion within the knee.

OBJECTIVE: To quantify the dynamic effects of anterior cruciate ligament deficiency on human knee joint motion. DESIGN: Three-dimensional motion was assessed by measuring the kinematics of intact and anterior cruciate ligament deficient knee joint specimens during simulated flexion-extension cycles. BACKGROUND: It is known that the anterior cruciate ligament plays an important role in controlling three-dimensional knee joint motion. Nevertheless, dynamic effects of deficiency are not fully understood. METHODS: Six cadaveric knees were tested in a knee joint motion and loading apparatus prior to and after anterior cruciate ligament resection. To determine if the kinematic results depended on additional loading, internal and external rotation moments of 3.4 Nm were axially applied to the tibia. The kinematics were analysed in terms of finite helical axes. RESULTS: Sectioning the anterior cruciate ligament had little effect on the orientations of the finite helical axes. However, applying moments did affect the axes orientation. In contrast, relative translations of the axes were significantly affected by the deficiency for all rotational moments applied. Referring to the individual knee anatomy the largest translation of 12.5 mm (median) occurred in medial/lateral direction. CONCLUSIONS: Anterior cruciate ligament rupture primarily causes a translation of the finite helical axes in medial/lateral direction. Consequently, increased anterior excursion of the tibia occurs (subluxation) and therefore dynamic instability.

Correction of axis misalignment in the analysis of knee rotations.

The Cardanic or Eulerian description is the most commonly used method for the description of in vivo knee rotation. It is based on the determination of external anatomical landmarks used for the decomposition of the position of the tibia relative to the femur by three rotations about three pre-defined axes. However, the in vivo localisation of external anatomical landmarks is known to be difficult and subjective. Even a small mislocalisation may lead to dramatic consequences: the Cardanic description may become irreproducible and angle values may be overestimated. This error is well documented in the literature and known as the "cross-talk effect". Therefore this study proposes an additional calibration step of the classic Cardanic description by a reorientation procedure of rotation axes. The procedure is based on biomechanical constraints of knee kinematics as they appear during a knee squat exercise using the finite helical axis (FHA) method and is independent of anatomical landmark. The method was validated with the help of a special set-up modelling a perfect knee. Furthermore, an inter-session reliability study was performed involving tests on two healthy subjects during knee squat exercises. We found that the reorientation procedure was more reproducible than the classic Cardanic description. We observed a maximum inter-session difference of 37.1 degrees for the adduction angle obtained with the classic Cardanic description. In contrast, the maximum angle difference obtained with the reorientation procedure was less than 10 degrees.

[Biomechanics of the tibiofemoral joint and knee braces]. / Zur Biomechanik des Tibiofemoralgelenks und deren Umsetzung bei Knieorthesen.

We investigated whether the kinematics of modern knee braces reflect the natural movement of the knee, especially with regard to the roll-glide ratio. Seven commercially available modern knee braces were analyzed in a new measuring unit with a 6-D positional registration system, which had been developed for this study. The results were compared to the theoretically postulated joint movements. All knee braces produced a roll-glide ratio different from the natural movement of the knee. Only the Townsend brace protected the anterior cruciate ligament at the beginning of the movement.Biomechanically, none of the knee braces tested provided efficient protection for the knee movement. We propose a new functional external joint, which allows restoration of the natural roll-glide mechanism of the articulating surfaces.

[Studies of incest]. / Untersuchungen zum Inzest.

Theories of the genesis of incest tabus are presented and possible causes of a high degree of latent incest criminality are discussed. On the basis of the evaluation of 32 forensic-psychiatric expertises, characteristics of the committers and criminogenic conditions of the delict are discussed. The author arrives at the opinion that there is no determined type of incestuous delinquents. Decisive causes of later incest criminality will certainly be found in insufficiently introjected value norms within emotionally disturbed parental families and in the mainly primarily disturbed families of the delinquent.