Elastoplastic stress analysis of functionally graded disc under internal pressure– complas XII

The study deals with elastoplastic stress analysis of a hollow disk made of functionally graded materials (FGMs) subjected to an internal pressure. The material properties of disc are assumed to vary radially according to power law function, but Poisson’s ratio is taken constant. Small deformations and a state of plane stress are presumed, and the analysis of disk is based on Von-Mises yield criterion. The materials are assumed to be linear strain hardening, isotropic and not be affected by temperature. Variation of stresses and displacements according to gradient parameters are investigated by using analytical and finite element method. The results show that gradient parameters have an important role in determining the elastoplastic stress of functionally graded disc

Lunar plume-surface interactions using rarefiedMultiphaseFoam

Understanding plume-surface interactions is essential to the design of lander modules and potential bases on bodies such as the Moon, as it is important to predict erosion patterns on the surface and the transport of the displaced regolith material. Experimentally, it is difficult to replicate the extra-terrestrial conditions (e.g. the effects of reduced gravity). Existing numerical tools have limited accessibility and different levels of sophistication in the modelling of regolith entrainment and subsequent transport. In this work, a fully transient open source code for solving rarefied multiphase flows, rarefiedMultiphaseFoam, is updated with models to account for solid-solid interactions and applied to rocket exhaust plume-lunar regolith interactions. Two different models to account for the solid-solid collisions are considered; at relatively low volume fractions, a stochastic collision model, and at higher volume fractions the higher fidelity multiphase particle-in-cell (MPPIC) method. Both methods are applied to a scaled down version of the Apollo era lunar module descent engine and comparisons are drawn between the transient simulation results. It is found that the transient effects are important for the gas phase, with the shock structure and stand-off height changing as the regolith is eroded by the plume. Both models predict cratering at early times and similar dispersion characteristics as the viscous erosion becomes dominant. In general, the erosion processes are slower with the multiphase particle-in-cell method because it accounts for more physical effects, such as enduring contacts and a maximum packing limit. It is found that even if the initial volume fraction is low, the stochastic collision method can become unreliable as the plume impinges on the surface and compresses the regolith particles, invalidating the method’s assumption of only binary collisions. Additionally, it is shown that the breakdown of the locally free-molecular flow assumption that is used to calculate the drag and heat transfer on the solid particles has a strong influence on the temperatures that the solid particles obtain

Enthesis tissue engineering: biological requirements meet at the interface

Tendon-to-bone interface (enthesis) exhibits a complex multiscale architectural and compositional organization maintained by a heterogeneous cellular environment. Orthopedic surgeons have been facing several challenges when treating tendon pullout or tear from the bony insertion due to unsatisfactory surgical outcomes and high retear rates. The limited understanding of enthesis hinders the development of new treatment options toward enhancing regeneration. Mimicking the natural tissue structure and composition is still a major challenge to be overcome. In this review, we critically assess current tendon-to-bone interface tissue engineering strategies through the use of biological, biochemical, or biophysical cues, which must be ultimately combined into sophisticated gradient systems. Cellular strategies are described, focusing on cell sources and cocultures to emulate a physiological heterotypic niche, as well as hypoxic environments, alongside with growth factor delivery and the use of platelet-rich hemoderivatives. Biomaterial design considerations are revisited, highlighting recent progresses in tendon-to-bone scaffolds. Mechanical loading is addressed to uncover prospective engineering advances. Finally, research challenges and translational aspects are considered. In summary, we highlight the importance of deeply investigating enthesis biology toward establishing foundational expertise and integrate cues from the native niche into novel biomaterial engineering, aiming at moving today's research advances into tomorrow's regenerative therapies.Authors thank the support from the European Union Framework Programme for Research and Innovation HORIZON2020 [TEAMING Grant agreement No 739572 - The Discoveries CTR]; FCT–Fundação para a Ciência e a Tecnologia for the PhD grant of IC [PD/BD/128088/2016]; the Project NORTE-01-0145-FEDER-000021:“Accelerating tissue engineering and personalized medicine discoveries by the integration of key enabling nanotechnologies, marine-derived biomaterials and stem cells”, supported by Norte Portugal Regional Operational Programme (NORTE 2020), under the PORTUGAL 2020 Partnership Agreement, through the European Regional Development Fund (ERDF) and the ERC Consolidator grant of ME [ERC-2017-CoG-772817]

Cause of Death and Predictors of All-Cause Mortality in Anticoagulated Patients With Nonvalvular Atrial Fibrillation : Data From ROCKET AF

M. Kaste on työryhmän ROCKET AF Steering Comm jäsen.Background-Atrial fibrillation is associated with higher mortality. Identification of causes of death and contemporary risk factors for all-cause mortality may guide interventions. Methods and Results-In the Rivaroxaban Once Daily Oral Direct Factor Xa Inhibition Compared with Vitamin K Antagonism for Prevention of Stroke and Embolism Trial in Atrial Fibrillation (ROCKET AF) study, patients with nonvalvular atrial fibrillation were randomized to rivaroxaban or dose-adjusted warfarin. Cox proportional hazards regression with backward elimination identified factors at randomization that were independently associated with all-cause mortality in the 14 171 participants in the intention-to-treat population. The median age was 73 years, and the mean CHADS(2) score was 3.5. Over 1.9 years of median follow-up, 1214 (8.6%) patients died. Kaplan-Meier mortality rates were 4.2% at 1 year and 8.9% at 2 years. The majority of classified deaths (1081) were cardiovascular (72%), whereas only 6% were nonhemorrhagic stroke or systemic embolism. No significant difference in all-cause mortality was observed between the rivaroxaban and warfarin arms (P=0.15). Heart failure (hazard ratio 1.51, 95% CI 1.33-1.70, P= 75 years (hazard ratio 1.69, 95% CI 1.51-1.90, P Conclusions-In a large population of patients anticoagulated for nonvalvular atrial fibrillation, approximate to 7 in 10 deaths were cardiovascular, whereasPeer reviewe

Financial development and economic growth nexus in the MENA countries: Bootstrap panel granger causality analysis

This paper investigates the direction of causality between financial development and economic growth in the Middle East and North African (MENA) countries. The panel causality testing approach, developed by Kónya (2006) [Kónya, L. (2006), exports and growth: Granger causality analysis on OECD countries with a panel data approach, Economic Modelling, 23, 978-992], based on the Seemingly Unrelated Regressions and Wald tests with the country specific bootstrap critical values, is applied to the panel of fifteen MENA countries for the period 1980-2007. In order to capture the different aspects of financial development, six different indicators are used. Empirical results show that there is no clear consensus on the direction of causality between financial development and economic growth for all measurements of financial development and it is also observed that the findings are country specific. © 2010 Elsevier B.V

Elastoplastic stress analysis of functionally graded disc under internal pressure– complas XII

The study deals with elastoplastic stress analysis of a hollow disk made of functionally graded materials (FGMs) subjected to an internal pressure. The material properties of disc are assumed to vary radially according to power law function, but Poisson’s ratio is taken constant. Small deformations and a state of plane stress are presumed, and the analysis of disk is based on Von-Mises yield criterion. The materials are assumed to be linear strain hardening, isotropic and not be affected by temperature. Variation of stresses and displacements according to gradient parameters are investigated by using analytical and finite element method. The results show that gradient parameters have an important role in determining the elastoplastic stress of functionally graded disc

Aplikasi Model Connoisseurship dan Kritikan Pendidikan Eisner: Kelebihan dan Kekurangannya dalam Penilaian Program Pendidikan

Model Connoisseurship dan Kritikan Eisner tidak banyak digunakan dalam menilai sesuatu program pendidikan. Aspek kritikan secara eksklusif, penuh berseni dan ketelitian mendalam berperanan besar dalam membantu aspek penilaian menjadi lebih bermakna. Penghuraian secara tersirat membawa dimensi baru dan mengelakkan aspek cliché. Artikel ini menghuraikan kandungan Model Connoisseurship dan Kritikan Eisner seperti latar belakang, kelebihan dan limitasi model dalam pelaksanaannya. Penjelasan kertas konsep ini menyokong idea untuk menggalakkan lagi pihak berkepentingan dalam sektor pendidikan memilih penilai dan pengkritik yang lebih kompeten kerana tidak semua penilai kompeten menilai secara berseni. Idea di sebalik kupasan ini membawa implikasi untuk menggalakkan Perubahan dalam melatih penilai program itu sendiri. Selain itu, kajian lanjut boleh dijalankan dengan membangunkan latihan khas buat penilai yang memenuhi Model Connoisseurship dan Kritikan Eisner. Tiada gunanya model yang mantap seperti ini tetapi tiada ramai penilai yang berkebolehan dalam konteks Malaysia

Fracture patterns and bone healing in recurrent mandibular fractures: A clinical study of 13 patients

BackgroundRecurrent fractures of the previously treated fractured mandible are rare.MethodsIn this retrospective study, 13 cases of repeated mandibular fractures were evaluated according to age, sex, cause, fracture localizations and patterns, treatment modalities, and complications.ResultsAll of the patients were men, with a mean age of 27.5 years and 32 years for the first and the subsequent fractures, respectively. The mean time interval between fractures was 4.3 years. In 10 cases, the cause for the second fracture was an assault, with 90 percent related to alcohol intake. Angle, body, and parasymphysis region of the mandible were the most common sites to be involved in the first occasion. In 10 cases, an internal rigid fixation procedure was performed for the treatment. In the recurrent injuries, none of the fractures occurred at exactly the same anatomical site. Fractures were either in the neighboring side or the contralateral side of the previously healed area of mandible. On the second occasion, angle fractures were common and body and subcondylar fracture rates increased. At second presentation, the complication rate increased from 23.1 percent to 53.8 percent and most commonly involving malocclusion.ConclusionsThis study showed that assault is the major etiologic factor for recurrent mandible fractures and that these fractures occur in different locations from the original injury. They necessitate a cautious approach for the prevention of unfavorable outcomes. Further retrospective clinical and experimental studies are necessary to elucidate the fracture patterns and bone-healing quality of these recurrent mandible fractures