Probing anisotropies of gravitational-wave backgroundswith a space-based interferometer II: Perturbative reconstruction of a low-frequency skymap

We present a perturbative reconstruction method to make a skymap of gravitational-wave backgrounds (GWBs) observed via space-based interferometer. In the presence of anisotropies in GWBs, the cross-correlated signals of observed GWBs are inherently time-dependent due to the non-stationarity of the gravitational-wave detector. Since the cross-correlated signal is obtained through an all-sky integral of primary signals convolving with the antenna pattern function of gravitational-wave detectors, the non-stationarity of cross-correlated signals, together with full knowledge of antenna pattern functions, can be used to reconstruct an intensity map of the GWBs. Here, we give two simple methods to reconstruct a skymap of GWBs based on the perturbative expansion in low-frequency regime. The first one is based on harmonic-Fourier representation of data streams and the second is based on "direct" time-series data. The latter method enables us to create a skymap in a direct manner. The reconstruction technique is demonstrated in the case of the Galactic gravitational wave background observed via planned space interferometer, LISA. Although the angular resolution of low-frequency skymap is rather restricted, the methodology presented here would be helpful in discriminating the GWBs of galactic origins by those of the extragalactic and/or cosmological origins.Comment: 23 pages, 12 figures, Phys.Rev.D (2005) in pres

Knee moments of anterior cruciate ligament reconstructed and control participants during normal and inclined walking

Objectives: Prior injury to the knee, particularly anterior cruciate ligament (ACL) injury, is known to predispose one to premature osteoarthritis (OA). The study sought to explore if there was a biomechanical rationale for this process by investigating changes in external knee moments between people with a history of ACL injury and uninjured participants during walking: (1) on different surface inclines and (2) at different speeds. In addition we assessed functional differences between the groups. Participants: 12 participants who had undergone ACL reconstruction (ACLR) and 12 volunteers with no history of knee trauma or injury were recruited into this study. Peak knee flexion and adduction moments were assessed during flat (normal and slow speed), uphill and downhill walking using an inclined walkway with an embedded Kistler Force plate, and a ten-camera Vicon motion capture system. Knee injury and Osteoarthritis Outcome Score (KOOS) was used to assess function. Multivariate analysis of variance (MANOVA) was used to examine statistical differences in gait and KOOS outcomes. Results: No significant difference was observed in the peak knee adduction moment between ACLR and control participants, however, in further analysis, MANOVA revealed that ACLR participants with an additional meniscal tear or collateral ligament damage (7 participants) had a significantly higher adduction moment (0.33±0.12 Nm/kg m) when compared with those with isolated ACLR (5 participants, 0.1±0.057 Nm/kg m) during gait at their normal speed ( p<0.05). A similar (nonsignificant) trend was seen during slow, uphill and downhill gait. Conclusions: Participants with an isolated ACLR had a reduced adductor moment rather an increased moment, thus questioning prior theories on OA development. In contrast, those participants who had sustained associated trauma to other key knee structures were observed to have an increased adduction moment. Additional injury concurrent with an ACL rupture may lead to a higher predisposition to osteoarthritis than isolated ACL deficiency alone

Dynamic Loading and Pain in Knee Osteoarthritis: Effects of Limb Realignment and Ligament Reconstruction Surgeries

Painful loading of the knee during walking is a key feature of knee osteoarthritis (OA). The external knee moments derived from three-dimensional gait analysis represent dynamic knee loads and may help evaluate surgical interventions. However, the relationships between knee moments and pain and the effects of surgery remain unclear. The overall purpose of this thesis was to investigate knee moments and pain during walking in patients with moderate medial knee OA, including the effects of limb realignment and ligament reconstruction surgeries. This thesis includes three studies investigating knee moments in patients with medial compartment tibiofemoral OA. Chapter 2 describes a cross-sectional study examining the relationship between knee pain and knee moments during walking, while controlling for extraneous factors by comparing limbs within 265 patients with medial knee OA. Using conditional logistic regression, results indicated greater odds of an increase in pain during walking with increased knee adduction moment, adduction impulse and internal rotation moment, and decreased knee flexion moment. These findings suggest a strong relationship between knee moments (in all three planes of motion) and knee pain during walking when between-person confounding is lessened. Chapter 3 describes a prospective cohort study evaluating the bilateral changes in knee moments in all three planes of motion in 33 patients undergoing combined medial opening-wedge high tibial osteotomy (HTO) and anterior cruciate ligament (ACL) reconstruction (HTO-ACLR). Patients underwent three-dimensional gait analysis, patient-reported outcomes and radiographic analysis preoperatively, 2 years postoperatively and a minimum 5 years postoperatively. Results indicated significant reductions in the knee adduction and internal rotation moments in the surgical limb, and a decrease in the knee flexion moment and an increase in the knee extension moment in both limbs. Changes in only the surgical limb suggest that HTO-ACLR reduces frontal and transverse plane knee moments. Bilateral changes suggest the passage of time, rather than the surgery, is responsible for the changes in sagittal plane knee moments. Chapter 4 describes a retrospective matched cohort study comparing preoperative and 5-year postoperative changes in the knee adduction and flexion moments in 52 patients who underwent either combined HTO-ACLR or HTO-Alone. Results indicated that both groups experienced a significant reduction in the knee adduction moment in the surgical limb. However, the HTO-Alone group also experienced a significant decrease in the knee flexion moment while the HTO-ACLR group experienced no change in sagittal plane knee moments. These findings suggest that HTO-ACLR may lessen the long-term decrease in the knee flexion moment typically observed over time in patients with knee OA. Overall, the results of this thesis support the use of investigating bilateral knee moments during walking in patients with medial knee OA, and provide rationale for future research examining whether the biomechanical changes observed in these individuals affects OA progression

Incidence and mechanism of the pivot shift. An in vitro study.

Accepted versio

Zernike velocity moments for sequence-based description of moving features

The increasing interest in processing sequences of images motivates development of techniques for sequence-based object analysis and description. Accordingly, new velocity moments have been developed to allow a statistical description of both shape and associated motion through an image sequence. Through a generic framework motion information is determined using the established centralised moments, enabling statistical moments to be applied to motion based time series analysis. The translation invariant Cartesian velocity moments suffer from highly correlated descriptions due to their non-orthogonality. The new Zernike velocity moments overcome this by using orthogonal spatial descriptions through the proven orthogonal Zernike basis. Further, they are translation and scale invariant. To illustrate their benefits and application the Zernike velocity moments have been applied to gait recognition—an emergent biometric. Good recognition results have been achieved on multiple datasets using relatively few spatial and/or motion features and basic feature selection and classification techniques. The prime aim of this new technique is to allow the generation of statistical features which encode shape and motion information, with generic application capability. Applied performance analyses illustrate the properties of the Zernike velocity moments which exploit temporal correlation to improve a shape's description. It is demonstrated how the temporal correlation improves the performance of the descriptor under more generalised application scenarios, including reduced resolution imagery and occlusion

Impact differences among the landing phases of a drop vertical jump in soccer players

The aim of this study was to examine the differences of landing phase biomechanics between the players who had anterior cruciate ligament (ACL) reconstruction and healthy participants during single leg drop vertical jump. In this study, 11 soccer players who had anterior cruciate ligament reconstruction (aged 23.0±3.6 years, height 177±5.0 cm, weight 83.8±11.7 kg) and 9 healthy soccer players( aged 22.2±2.4 years, height 178±3.0 cm, weight 74.3±6.1 kg) participated voluntarily. During the data collection phase three high speed cameras synchronized to each other and force plate were used. Visual analysis programme and MATLAB were used to calculate kinetic and kinematic variables. Landing techniques of the subjects' were examined by flexion angle of knee, ground reaction force and moment parameters. The statistical analyses of the measured results were performed by t-test and Pearson Correlation analysis. According to the results, it was determined that peak vertical ground reaction force exhibited significant phase differences (p=0.00, and p=0.00, respectively) between the groups. Obtained results can be explained with "quadriceps avoidance" motion pattern which is characterized by decreased quadriceps activity and lower external knee flexion moment in an effort to control anterior translation of the tibia in subjects with ACL reconstruction. A better understanding of the different phases during single-leg landings can shed a light on mechanism of non-contact anterior crucaite ligament injuries therefore future researches should assess how phase differences affect drop vertical jump performance. © 2018 Montenegrin Sports Academy. All rights reserved

Semileptonic B Decays in Babar

BaBar measurements involving semileptonic decays of B mesons are reviewed. Attention is focused on the extraction of |Vub| and |Vcb| elements of the Cabibbo-Kobayashi-Maskawa quark mixing matrix. Recent results of inclusive and exclusive approaches are presented.Comment: 6 pages, 4 figures, Contributed to 11th Lomonosov Conference on Elementary Particle Physic