Constrained Statistical Modelling of Knee Flexion from Multi-Pose Magnetic Resonance Imaging

© 1982-2012 IEEE.Reconstruction of the anterior cruciate ligament (ACL) through arthroscopy is one of the most common procedures in orthopaedics. It requires accurate alignment and drilling of the tibial and femoral tunnels through which the ligament graft is attached. Although commercial computer-Assisted navigation systems exist to guide the placement of these tunnels, most of them are limited to a fixed pose without due consideration of dynamic factors involved in different knee flexion angles. This paper presents a new model for intraoperative guidance of arthroscopic ACL reconstruction with reduced error particularly in the ligament attachment area. The method uses 3D preoperative data at different flexion angles to build a subject-specific statistical model of knee pose. To circumvent the problem of limited training samples and ensure physically meaningful pose instantiation, homogeneous transformations between different poses and local-deformation finite element modelling are used to enlarge the training set. Subsequently, an anatomical geodesic flexion analysis is performed to extract the subject-specific flexion characteristics. The advantages of the method were also tested by detailed comparison to standard Principal Component Analysis (PCA), nonlinear PCA without training set enlargement, and other state-of-The-Art articulated joint modelling methods. The method yielded sub-millimetre accuracy, demonstrating its potential clinical value

The Correlation between Electroencephalography Amplitude and Interictal Abnormalities : Audit study

Objectives: The aim of this study was to establish the relationship between background amplitude and interictal abnormalities in routine electroencephalography (EEG). Methods: This retrospective audit was conducted between July 2006 and December 2009 at the Department of Clinical Physiology at Sultan Qaboos University Hospital (SQUH) in Muscat, Oman. A total of 1,718 electroencephalograms (EEGs) were reviewed. All EEGs were from patients who had been referred due to epilepsy, syncope or headaches. EEGs were divided into four groups based on their amplitude: group one ≤20 μV; group two 21–35 μV; group three 36–50 μV, and group four >50 μV. Interictal abnormalities were defined as epileptiform discharges with or without associated slow waves. Abnormalities were identified during periods of resting, hyperventilation and photic stimulation in each group. Results: The mean age ± standard deviation of the patients was 27 ± 12.5 years. Of the 1,718 EEGs, 542 (31.5%) were abnormal. Interictal abnormalities increased with amplitude in all four categories and demonstrated a significant association (P <0.05). A total of 56 EEGs (3.3%) had amplitudes that were ≤20 μV and none of these showed interictal epileptiform abnormalities. Conclusion: EEG amplitude is an important factor in determining the presence of interictal epileptiform abnormalities in routine EEGs. This should be taken into account when investigating patients for epilepsy. A strong argument is made for considering long-term EEG monitoring in order to identify unexplained seizures which may be secondary to epilepsy. It is recommended that all tertiary institutions provide EEG telemetry services

Effects of Pranayam Breathing on Respiratory Pressures and Sympathovagal Balance of Patients with Chronic Airflow Limitation and in Control Subjects

Objectives: The objective of this study was to compare the effects of Pranayam breathing on respiratory muscle strength measured as maximum expiratory and inspiratory pressures (MEP and MIP) and relevant spirometry parameters in patients with chronic obstructive pulmonary disease (COPD) and in control subjects, and on the sympatho-vagal balance in both the groups. Methods: The research was performed in the Clinical Physiology Department, Sultan Qaboos University Hospital, Oman. Eleven patients (mean age 43.91 ± 20.56 yr; mean BMI 21.9 ± 5.5 kg/m2) and 6 controls (43.5 ± 14.6yr; 25.4 ± 3.2 kg/m2) learnt and practised Pranayam. Their respiratory and cardiovascular parameters were recorded. Their respiratory “well being” was noted as a visual analogue score (VAS). The respiratory parameters were expressed as a percentage change of predicted values. Results: Patients’ respiratory parameters were significantly lower than those of controls. Patients’ maximum respiratory pressures did not improve after Pranayam; however, they showed significant improvement in VAS 5.4 ± 2.4 to 7.2 ± 1.2 (P < 0.03). Controls showed significant increase in MIP after Pranayam exercises. There were no changes in other spirometry indices. Controls showed significant increase in their systolic blood pressure and stroke index after exercise. The vago-sympathetic balance shifted towards sympathetic in both patients and controls after exercise. Conclusion: The improvement in MIP in controls indicated the positive effect of Pranayam exercise; however, it may not be an adequately stressful exercise to produce changes in the respiratory parameters of COPD patients. The increase in VAS in patients suggested improvement in respiratory distress and quality of life.

Seismic microzonation for Muscat region, Sultanate of Oman

Site characterization was carried out for Muscat region using the ambient noise measurements applying the horizontal-to-vertical spectral ratio (HVSR) technique and using active seismic survey utilizing the multichannel analysis of surface waves (MASW) of survey data. Microtremors measurements were carried out at 459 sites using short-period sensors. This extensive survey allowed the fundamental resonance frequency of the soft soil to be mapped and areas prone to site amplification to be identified. The results indicate a progressive decrease in the fundamental resonance frequencies from the southern and eastern parts, where the bedrock outcrops, toward the northern coast where a thickness of sedimentary cover is present. Shear wave velocity (Vs) was evaluated using the 2-D MASW at carefully selected 99 representative sites in Muscat. These 99 sites were investigated with survey lines of 52 m length. 1-D and interpolated 2-D profiles were generated up to a depth range 20–40 m. The vertical Vs soundings were used in the SHAKE91 software in combination with suitable seismic input strong motion records to obtain the soil effect. Most of the study area has amplification values less than 2.0 for all the considered spectral periods. The estimated fundamental frequencies obtained using the H/V spectral ratio method and using SHAKE91 are found to be in a relatively good agreement. Maps of spectral amplification, earthquake characteristics on the ground surface for peak ground and spectral accelerations at 0.1, 0.2, 0.3, 1.0, and 2.0 s, for 475 years return period are produced. The surface ground motion maps show that the hazard level is moderate with expected PGA in the range 0.059–0.145 g for 475 years return period.Oman Ministerial Cabinet (project # 22409017

Structural, 57 Fe Mössbauer and XPS studies of mechanosynthesized nanocrystalline Nd0.33Eu0.67Fe1-xCrxO3 particles

We report on the structure and surface composition of Nd0.33Eu0.67Fe1-xCrxO3 (x = 0.0, 0.3, 0.5, 0.7, 0.9 and 1.0) nanoparticles (∼30 nm) mechanosynthesized at temperatures that are ∼ 470– 700 °C lower than those at which the pure and doped pristine materials conventionally form. XRD Rietveld and FT-IR analyses show that with increasing x the lattice parameters decrease and the bond lengths and angles vary in a way that reduces crystalline distortion. Whilst the majority of the Eu3+/Nd3+ and Fe3+/Cr3+ cations occupy the normal perovskite-related A- and B-sites, respectively, ∼ 5% of them exchange sites. 57Fe Mössbauer spectroscopy confirms the presence of these antisites and reveals a superparamagnetic behaviour at 298 K that enhances with increasing x. XPS measurement reveals a complex surface composition of the nanoparticles with traces of Eu2O3, Nd2O3, Cr2O3 and Fe2O3 as well as partial O2--deficiency

The hyperfine properties of a hydrogenated Fe/V superlattice

: We study the effect of hydrogen on the electronic, magnetic and hyperfine structures of an iron-vanadium superlattice consisting of three Fe monolayers and nine V monolayers. The contact charge density ({\rho}), the contact hyperfine field (Bhf) and the electronic field gradient (EFG) at the Fe sites for different H locations and H fillings are calculated using the first principle full-potential linear-augmented-plane-wave (FP-LAPW) method . It is found that sizeable changes in the hyperfine properties are obtained only when H is in the interface region.Comment: 6 pages, 2 figures, 3 tables, ICAME 2011 conference (Kobe, Japan

Immigrants and health system challenges to TB control in Oman

<p>Abstract</p> <p>Background</p> <p>During the past three decades, Oman has made significant progress in controlling TB within it's borders. However, the national TB control program elimination target has yet to be reached. This study aims to explore the perceived roles played by the immigrant population and the private health sector in relation to TB control in Oman.</p> <p>Methods</p> <p>We conducted seventeen interviews with different health care providers. The verbatim transcripts were processed using content analysis.</p> <p>Results</p> <p>Three main themes emerged. Firstly the threat of repatriation faced by underprivileged expatriates, secondly the criticized and forgotten private health sector as a key player and thirdly the user and provider barriers faced by Omani patients in the Omani public health system.</p> <p>Conclusions</p> <p>The study has identified some of the challenges and barriers to TB control in Oman. These challenges are mainly related to unintended negative consequences arising from the current repatriation policy of immigrants and to and the lack of involvement of the private sector in TB control. TB control strategies designed to address these challenges are needed, for Oman to reach its TB elimination targets.</p

Twelve-month observational study of children with cancer in 41 countries during the COVID-19 pandemic

Introduction Childhood cancer is a leading cause of death. It is unclear whether the COVID-19 pandemic has impacted childhood cancer mortality. In this study, we aimed to establish all-cause mortality rates for childhood cancers during the COVID-19 pandemic and determine the factors associated with mortality. Methods Prospective cohort study in 109 institutions in 41 countries. Inclusion criteria: children &lt;18 years who were newly diagnosed with or undergoing active treatment for acute lymphoblastic leukaemia, non-Hodgkin's lymphoma, Hodgkin lymphoma, retinoblastoma, Wilms tumour, glioma, osteosarcoma, Ewing sarcoma, rhabdomyosarcoma, medulloblastoma and neuroblastoma. Of 2327 cases, 2118 patients were included in the study. The primary outcome measure was all-cause mortality at 30 days, 90 days and 12 months. Results All-cause mortality was 3.4% (n=71/2084) at 30-day follow-up, 5.7% (n=113/1969) at 90-day follow-up and 13.0% (n=206/1581) at 12-month follow-up. The median time from diagnosis to multidisciplinary team (MDT) plan was longest in low-income countries (7 days, IQR 3-11). Multivariable analysis revealed several factors associated with 12-month mortality, including low-income (OR 6.99 (95% CI 2.49 to 19.68); p&lt;0.001), lower middle income (OR 3.32 (95% CI 1.96 to 5.61); p&lt;0.001) and upper middle income (OR 3.49 (95% CI 2.02 to 6.03); p&lt;0.001) country status and chemotherapy (OR 0.55 (95% CI 0.36 to 0.86); p=0.008) and immunotherapy (OR 0.27 (95% CI 0.08 to 0.91); p=0.035) within 30 days from MDT plan. Multivariable analysis revealed laboratory-confirmed SARS-CoV-2 infection (OR 5.33 (95% CI 1.19 to 23.84); p=0.029) was associated with 30-day mortality. Conclusions Children with cancer are more likely to die within 30 days if infected with SARS-CoV-2. However, timely treatment reduced odds of death. This report provides crucial information to balance the benefits of providing anticancer therapy against the risks of SARS-CoV-2 infection in children with cancer

Taking two to tango:fMRI analysis of improvised joint action with physical contact

<div><p>Many forms of joint action involve physical coupling between the participants, such as when moving a sofa together or dancing a tango. We report the results of a novel two-person functional MRI study in which trained couple dancers engaged in bimanual contact with an experimenter standing next to the bore of the magnet, and in which the two alternated between being the leader and the follower of joint improvised movements. Leading showed a general pattern of self-orientation, being associated with brain areas involved in motor planning, navigation, sequencing, action monitoring, and error correction. In contrast, following showed a far more sensory, externally-oriented pattern, revealing areas involved in somatosensation, proprioception, motion tracking, social cognition, and outcome monitoring. We also had participants perform a “mutual” condition in which the movement patterns were pre-learned and the roles were symmetric, thereby minimizing any tendency toward either leading or following. The mutual condition showed greater activity in brain areas involved in mentalizing and social reward than did leading or following. Finally, the analysis of improvisation revealed the dual importance of motor-planning and working-memory areas. We discuss these results in terms of theories of both joint action and improvisation.</p></div