Popliteus impingement after TKA may occur with well-sized prostheses

To determine the mechanisms and extents of popliteus impingements before and after TKA and to investigate the influence of implant sizing. The hypotheses were that (1) popliteus impingements after TKA may occur at both the tibia and the femur, and (2) even with an apparently well-sized prosthesis, popliteal tracking during knee flexion is modified compared to the preoperative situation. The location of the popliteus in three cadaver knees was measured using computed tomography, before and after implantation of plastic TKA replicas, by injecting the tendon with radiopaque liquid. The pre- and post-operative positions of the popliteus were compared from full extension to deep flexion using normosized, oversized, and undersized implants (one size increments). At the tibia, TKA caused the popliteus to translate posteriorly, mostly in full extension: 4.1 +/- 2 mm for normosized implants, and 15.8 +/- 3 mm with oversized implants, but no translations were observed when using undersized implants. At the femur, TKA caused the popliteus to translate laterally at deeper flexion angles, peaking between 80A degrees and 120A degrees: 2 +/- 0.4 mm for normosized implants and 2.6 +/- 0.5 mm with oversized implants. Three-dimensional analysis revealed prosthetic overhang at the posterosuperior corner of normosized and oversized femoral components (respectively, up to 2.9 mm and 6.6 mm). A well-sized tibial component modifies popliteal tracking, while an undersized tibial component maintains more physiologic patterns. Oversizing shifts the popliteus considerably throughout the full arc of motion. This study suggests that both femoro- and tibio-popliteus impingements could play a role in residual pain and stiffness after TKA

X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), differential scanning calorimetry (DSC) and density study of ternary chalcogenide glasses based on Ge-Se and Ge-S

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.Glasses of the systems Ge-Se-X (X = Ga, Sn, Bi, Sb), Ge-S-Y (Y = Ag, Ga, Sn, Bi) and Se-S have been examined using X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), density and differential scanning calorimetry (DSC). Two of the compositions, GeSe2 and (GeSe2)92Ga8, have also been examined by extended X-ray absorption fine structure (EXAFS) and X-ray absorption near edge structure (XANES). The emphasis of the XPS measurements was on the changes in the binding energies with composition of the core peaks of the glasses, and on the plasmon energy losses from the L3M4,5M4,5 Auger lines of Se and Ge. It was found that there were small shifts in the binding energies of the core peaks on substitution but the plasmon energy changed markedly with composition. For the XRD measurements, the focus was on two features : (a) to ensure that the samples prepared were truely amorphous and (b) to confirm the presence of the first sharp diffraction peak (FSDP) on the interference functions. The density measurements showed that the addition of the third element (X or Y) to the binary resulted in an increase in the relative density except for one system, Ge-Se-Sn, which showed the opposite behaviour. The DSC measurements showed that the addition of the third element to the binary resulted in a decrease in the glass transition temperatures. The EXAFS and XANES measurements of GeSe2 and (GeSe2)92Ga8 glasses showed that there was very little change in the local order around the Ge atom in GeSe2 glass with increase in temperature and that the local order around the Ge atom changes on alloying GeSe2 with Ga. Correlations between parameters and measured properties of the ternary alloys have been investigated. It has been found that the parameter , the average coordination number, correlates well with certain structural properties but badly with others. Suggestions are made for an alternative to .This study was funded by the British Council

Onset of rigidty in glasses: from random to self-organized networks

We review in this paper the signatures of a new elastic phase that is found in glasses with selected compositions. It is shown that in contrast with random networks, where rigidity percolates at a single threshold, networks that are able to self-organize to avoid stress will remain in an almost stress- free state during a compositional interval, an intermediate phase, that is bounded by a flexible phase and a stressed rigid phase. We report the experimental signatures and describe the theoretical efforts that have been accomplished to characterize the intermediate phase. We illustrate one of the methods used in more detail with the example of Group III chalcogenides and finally suggest further possible experimental signatures of self-organization.Comment: 27 pages, 6 figures, Proceedings of the Conference on Non-Crystalline Materials 10, to appear in Journal of Non-Crystalline Solid

Imaging the implant-soft tissue interactions in total knee arthroplasty

BACKGROUND: In Total Knee Arthroplasty (TKA), residual pain may be secondary to soft tissue impingements, which are difficult to visualize around chromium-cobalt implants using medical imaging, so their interactions remain poorly understood. The goal of this work was to establish a protocol for in-vitro imaging of the soft tissues around TKA, usable during throughout the range of motion (ROM). METHODS: The full size range of a commercially available TKA prosthesis was manufactured by 3D-printing in non-magnetic and non-radiopaque polymer and implanted in 12 cadaveric knees. The relations between these implants and the soft tissues (Popliteus tendon, Medial and Lateral Collateral Ligament, Patellar and Quadriceps tendons) were analyzed, using MRI (5 embalmed specimens) and CT scans after injection of the tissues with barium-sulfate (3 embalmed and 4 fresh-frozen specimens). RESULTS: Both MRI and CT scans enabled good identification of the soft tissues before TKA implantation. MRI produced minimal loss in signal and contrast, and neither the low temperature nor the embalming fluids compromised image quality. CT scans were more precise after TKA implantation, particularly the borders of the implant and the differentiation of soft tissues. Full ROM investigation, manual segmentation and three-dimensional reconstructions were possible only with the CT scan. CONCLUSION: The experimental approach described in this study was successful in visualizing the interactions between the soft tissue and the implants before and after TKA and during the full ROM. The coordinate system allows to localize precisely the different anatomic structures and to quantify any change due to prosthetic implantation

Atomistic Thermo-mechanical Description of the Deformation Behavior, Scaling Laws, and Constitutive Modeling of Nanoporous Gold

Metallic foams, or nanoporous (NP) metals as it is widely referred to in literature, with ligament sizes up to a few tens of nm show exceptional mechanical properties such as high strength and stiffness per weight ratio under different loading scenarios due to their high surface area to solid volume ratio. Therefore, they can be utilized in a wide range of applications making them of great interest to researchers. While their elasticity and yield strength have been the subject of several studies, very limited attention was given to the effect of size, strain rate, and temperature on the material plastic response. Moreover, despite the significant attention in the literature that is directed towards the development of scaling laws that relate the properties of nanoporous metals to bulk materials, the literature still lacks a specific model that predicts the material mechanical properties based on a combination of parameters capturing the effect of surface area, ligament size, relative density, strain rate, and temperature. Therefore, the effect of ligament size, strain rate, and temperature are investigated using large-scale atomistic simulations to probe the elastic response, plastic response, and deformation mechanisms of nanoporous gold under uniaxial compression and tension and up to strains in excess of 60 percent for strain rates in the range of 106 ��−1 and 109 ��−1 at temperatures between 300K and 700K. This work explores the full range of the material response, focusing on the modifications to strain hardening and densification under compression and on the ductility and failing mechanisms under tension. Additionally, by utilizing the literature reported results, scaling laws that account for the effect of surface area to solid volume ratio, ligament size, relative density, strain rate, and temperature to predict the elastic modulus, yield stress, and ultimate stress are proposed. Finally, a size, relative density, strain rate, and temperature dependent dislocation based constitutive model that describes the plastic flow in NP-Au is proposed. The results reported in this work will eventually help enhancing the design of novel metallic foams with tailored mechanical response

Smart System to Avoid Car Accidents

Car accidents have different reasons, they are either caused by external (outside the car) or internal factors (inside the car). Accidents due to external reasons occur because of environmental reasons such as obstructed vision of the driver due to fog or bad road conditions. Internal factors include decreased amount of Oxygen, and in turn increase the amount of carbon dioxide, driver sleep, humidity and temperature ratio between outside and inside the car, which cause condensation on the front windshield which limits the vision of the driver. To avoid car accidents, one should minimize both external as well as internal accident reasons. In this paper, a system consisting of two parts is proposed to monitor the external and internal driving conditions. The first one focuses on external accident conditions, which monitors the road and notifies the driver about any problem in front of him and take action to avoid it, by reducing their speed, increase the lights of the car, or by using smart bumps that come out when needed (the risk of sliding for example) to enforce the driver to drive slowly and carefully. These smart bumps are needed also when the sensors detect that the driver feels sleepy. Activating them will reduce the probability of an accident. Additionally, if the humidity and temperature of the environments increased over a specified range, fans are activated to cool down the temperature inside the car. The other system works inside the car. If the air conditions pose a danger on the driver (the temperature, or CO2 increased for example), the system takes an action by starting the air condition or opening the windows to balance the temperature or CO2 ratios. The system will be applied by using sensors to measure factors inside and outside the car, which in turn tells the cars what to do by the interaction between both systems via the internet

Some notes concerning the qurrā’ issue

It has been noticed that some scholars in their attempt to discover something new in their researches, deplorably distort the clear facts of history. An example of this is their dealing with the qurrā’ issue in the early Islamic history. M.A. Shaban, followed by G.H.A. Juynboll, assumes that the term qurrā’ “should be understood no more than another derivation from the root qry and meaning the same as ahl al-qurà (those of the villages)”. His reference to Al-Balāḏūrī (Futūḥ, 88) to confirm his assumption cannot, however, be traced. Basing himself on this assumption, he tries to interpret accordingly the events of the rebellion against ‘Uṯmān, as an issue between the qurrā’ and the unfortunate caliph, and explain accordingly their role played in these and the following events until they became either Šī‘a or Ḫawāriǧ. Here Shaban is supported by Martin Hinds, who also tries to ascribe the causes of discontent in the later days of ‘Uṯmān to self-interest among these qurrā’. The purpose of this article is not to discuss the issues at stake between ‘Uṯmān and his opponents, but to shed more light on the qurrā’ and their actual role in those events.Maciej Klimiu

Image classification in cultural heritage

In this paper, an automated supervised image classification technique, specifi- cally for classifying images in the cultural heritage domain, is developed. The developed technique classifies images according to a particular date, culture, people and historical age. The proposed technique consists of two stages, fea- ture extraction using the unsupervised segmentation technique, and the classi- fication stage using supervised classification techniques. Common features are extracted, and their histograms are applied to three classifiers: k-nearest neigh- bor (KNN), logistic regression (LR), and decision tree (DT). When our tech- nique was applied to a repository of images from cultural heritage, it showed reduced complexity and improved classification accuracy. DT has achieved a higher weighted average recall. This is also represented by the weighted av- erage f-measure where DT has obtained 0.81. DT has outperformed the other classifiers in terms of classifying heritage images

Aerobic Respiration and Its Regulation in the Metal Reducer Shewanella Oneidensis

Shewanella oneidensis MR-1 is a facultative anaerobe known for its ability to reduce metal oxides. Anaerobic respiration, especially metal reduction, has been the subject of extensive research. In contrast, S. oneidensis aerobic respiration has received less attention. S. oneidensis expresses cbb3- and aa3-type cytochrome c oxidases and a bd-type quinol oxidase. The aa3-type oxidase, which in other bacteria is the major oxygen reductase under oxygen replete conditions, does not appear to contribute to aerobic respiration and growth in S. oneidensis. Our results indicated that although the aa3-type oxidase does not play a role in aerobic growth on lactate, the preferred carbon source for S. oneidensis, it is involved in growth on pyruvate or acetate. These results highlight the importance of testing multiple carbon and energy sources when attempting to identify enzyme activities and mutant phenotypes. Several regulatory proteins contribute to the regulation of aerobic growth in S. oneidensis including CRP and ArcA. The 3\u27,5\u27-cAMP phosphodiesterase (CpdA) appears to play a more significant role in aerobic growth than either CRP or ArcA, yet the deficiency does not appear to be the result of reduced oxidase genes expression. Interestingly, the ΔcpdA mutant was more deficient in aerobic respiration with several carbon sources tested compared to Δcrp, which was moderately deficient only in the presence of lactate. To identify the reason for ΔcpdA aerobic growth deficiency, we isolated a suppressor mutant with transposon insertion in SO_3550. Inactivation of this gene, which encodes an anti-sigma factor, restored aerobic growth in the cpdA mutant to wild-type levels. Inactivation of SO_3550 in wild-type cells, however, did not affect aerobic growth. The S. oneidensis genome encodes two additional CRP-like proteins that we designated CrpB and CrpC. Mutants that lack crpB and crpC were deficient in aerobic growth, but this deficiency was not due to the loss of oxidase gene expression.Keywords: aerobi

Arabic Poetry of Depression and Anxiety in Pre-Islamic and Early Islamic Days

Poetry usually tells much of the life and the different feelings of the poet in different situations. It reflects his state of joy and happiness as well as his fears, nervousness, worries and sadness. The phenomenon of anxiety, worry, depression and gloominess is often a characteristic of some of the early, particularly pre-Islamic Arabic poetry. There were many causes for such feelings: continuous tribal wars, loss of a brother, a son, a husband etc., hard life and poverty, love and disappoint- ment or failure in love, old age and frailty, being disowned by the tribe and left as an outcast with no tribal protection, as well as many other things. Generally speaking, pre-Islamic poetry is characterized by being a natural reflection of the genuine feelings of the individual poet. He lives his life, suffers from misfortunate incidents, falls in love, meets disappointment. suffers from the hardships of life. from fatigue, hunger, fear and other misfortunes. Naturally, he reflects on his responsibilities towards himself. his family, his tribe, joins raids against other tribes, admires bravery and generosity of his fellow tribesmen as well as others. He also reflects on nature around him, and admires beauty when he is endowed with some sensitive feelings. His poetry is then a reflection to all this. He utters verses spontaneously as some talk to others or to themselves, that is naturally. describing his feelings and experiences. Apart from some professional poets, his poetry comes natural, springing from true, and not artificial feelings. If he praises his fellow tribesman for his generosity or bravery shown in battle, or laments his death, he is often describing his own genuine emotions and feelings. Pre-Islamic and early Islamic poetry, it can be said, is often the reflection of some experiences and effects on the poet, sincerely expressed in his poetic utterance. It is characterized by realism, sensitivity marred often by pessimism towards life, and often showing his admiration of beauty in nature.Maciej Klimiu