A constitutive material model for nonlinear finite element structural analysis using an iterative matrix approach

A unified numerical method for the integration of stiff time dependent constitutive equations is presented. The solution process is directly applied to a constitutive model proposed by Bodner. The theory confronts time dependent inelastic behavior coupled with both isotropic hardening and directional hardening behaviors. Predicted stress-strain responses from this model are compared to experimental data from cyclic tests on uniaxial specimens. An algorithm is developed for the efficient integration of the Bodner flow equation. A comparison is made with the Euler integration method. An analysis of computational time is presented for the three algorithms

Constitutive modeling for isotropic materials (HOST)

The results of the first year of work on a program to validate unified constitutive models for isotropic materials utilized in high temperature regions of gas turbine engines and to demonstrate their usefulness in computing stress-strain-time-temperature histories in complex three-dimensional structural components. The unified theories combine all inelastic strain-rate components in a single term avoiding, for example, treating plasticity and creep as separate response phenomena. An extensive review of existing unified theories is given and numerical methods for integrating these stiff time-temperature-dependent constitutive equations are discussed. Two particular models, those developed by Bodner and Partom and by Walker, were selected for more detailed development and evaluation against experimental tensile, creep and cyclic strain tests on specimens of a cast nickel base alloy, B19000+Hf. Initial results comparing computed and test results for tensile and cyclic straining for temperature from ambient to 982 C and strain rates from 10(exp-7) 10(exp-3) s(exp-1) are given. Some preliminary date correlations are presented also for highly non-proportional biaxial loading which demonstrate an increase in biaxial cyclic hardening rate over uniaxial or proportional loading conditions. Initial work has begun on the implementation of both constitutive models in the MARC finite element computer code

Effect of a Fundamental Motor Skills Intervention on Fundamental Motor Skill and Physical Activity in a Preschool Setting: A Cluster Randomized Controlled Trial

Purpose: To determine the effect of a 12-week fundamental motor skill (FMS) program on FMS and physical activity (PA) on preschool-aged children. Method: A cluster randomized controlled trial. The intervention (PhysicaL ActivitY and Fundamental Motor Skills in Pre-schoolers [PLAYFun] Program) was a 12-week games-based program, delivered directly to the children in childcare centers by exercise physiologists. Children in the control arm received the usual preschool curriculum. Outcomes included FMS competence (Test of Gross Motor Development-2) and PA (accelerometer) assessed at baseline, 12 weeks, and 24 weeks (12-wk postintervention). Results: Fifty children (mean age = 4.0 [0.6] y; 54% male) were recruited from 4 childcare centers. Two centers were randomized to PLAYFun and 2 centers were randomized to the waitlist control group. Children attended on average 2.0 (1.0) 40-minute sessions per week. The PLAYFun participants demonstrated significant increases in object control (P < .001) and total FMS (P = .010) competence at week 12, compared with controls in a group × time interaction. Girls, but not boys, in PLAYFun significantly increased moderate to vigorous PA after the intervention (P = .004). These increases were not maintained 12-week postcompletion of PLAYFun. Conclusions: The PLAYFun Program is effective at improving FMS competence in boys and girls and increasing PA in girls. However, improvements are not maintained when opportunities to practice are not sustained

Solitary metastatic adenocarcinoma of the sternum treated by total sternectomy and chest wall reconstruction using a Gore-Tex patch and myocutaneous flap: a case report

<p>Abstract</p> <p>Introduction</p> <p>The consequences of bone metastasis are often devastating. Although the exact incidence of bone metastasis is unknown, it is estimated that 350,000 people die of bone metastasis annually in the United States. The incidence of local recurrences after mastectomy and breast-conserving therapy varies between 5% and 40% depending on the risk factors and primary therapy utilized. So far, a standard therapy of local recurrence has not been defined, while indications of resection and reconstruction considerations have been infrequently described. This case report reviews the use of sternectomy for breast cancer recurrence, highlights the need for thorough clinical and radiologic evaluation to ensure the absence of other systemic diseases, and suggests the use of serratus anterior muscle flap as a pedicle graft to cover full-thickness defects of the anterior chest wall.</p> <p>Case presentation</p> <p>We report the case of a 70-year-old Caucasian woman who was referred to our hospital for the management of a retrosternal mediastinal mass. She had undergone radical mastectomy in 1999. Computed tomography and magnetic resonance imaging revealed a 74.23 × 37.7 × 133.6-mm mass in the anterior mediastinum adjacent to the main pulmonary artery, the right ventricle and the ascending aorta. We performed total sternectomy at all layers encompassing the skin, the subcutaneous tissues, the right pectoralis major muscle, all the costal cartilages, and the anterior part of the pericardium. The defect was immediately closed using a 0.6 mm Gore-Tex cardiovascular patch combined with a serratus anterior muscle flap. Our patient had remained asymptomatic during her follow-up examination after 18 months.</p> <p>Conclusion</p> <p>Chest wall resection has become a critical component of the thoracic surgeon's armamentarium. It may be performed to treat either benign conditions (osteoradionecrosis, osteomyelitis) or malignant diseases. There are, however, very few reports on the results of full-thickness complete chest wall resections for locally recurrent breast cancer with sufficient safety margins, and even fewer reports that describe the operative technique of using the serratus anterior muscle as a pedicled flap.</p

Atypical PKCiota Contributes to Poor Prognosis Through Loss of Apical-basal Polarity and Cyclin E Overexpression in Ovarian Cancer

We show that atypical PKCι, which plays a critical role in the establishment and maintenance of epithelial cell polarity, is genomically amplified and overexpressed in serous epithelial ovarian cancers. Furthermore, PKCι protein is markedly increased or mislocalized in all serous ovarian cancers. An increased PKCι DNA copy number is associated with decreased progression-free survival in serous epithelial ovarian cancers. In a Drosophila in vivo epithelial tissue model, overexpression of persistently active atypical PKC results in defects in apical-basal polarity, increased Cyclin E protein expression, and increased proliferation. Similar to the Drosophila model, increased PKCι proteins levels are associated with increased Cyclin E protein expression and proliferation in ovarian cancers. In nonserous ovarian cancers, increased PKCι protein levels, particularly in the presence of Cyclin E, are associated with markedly decreased overall survival. These results implicate PKCι as a potential oncogene in ovarian cancer regulating epithelial cell polarity and proliferation and suggest that PKCι is a novel target for therapy

An Overview of the Management of Flexor Tendon Injuries

Flexor tendon injuries still remain a challenging condition to manage to ensure optimal outcome for the patient. Since the first flexor tendon repair was described by Kirchmayr in 1917, several approaches to flexor tendon injury have enabled successful repairs rates of 70-90%. Primary surgical repair results in better functional outcome compared to secondary repair or tendon graft surgery. Flexor tendon injury repair has been extensively researched and the literature demonstrates successful repair requires minimal gapping at the repair site or interference with tendon vascularity, secure suture knots, smooth junction of tendon end and having sufficient strength for healing. However, the exact surgical approach to achieve success being currently used among surgeons is still controversial. Therefore, this review aims to discuss the results of studies demonstrating the current knowledge regarding the optimal approach for flexor tendon repair. Post-operative rehabilitation for flexor tendon surgery is another area, which has caused extensive debate in hand surgery. The trend to more active mobilisation protocols seems to be favoured but further study in this area is needed to find the protocol, which achieves function and gliding but avoids rupture of the tendons. Lastly despite success following surgery complications commonly still occur post surgery, including adhesion formation, tendon rupture and stiffness of the joints. Therefore, this review aims to discuss the appropriate management of these difficulties post surgery. New techniques in management of flexor tendon will also be discussed including external laser devices, addition of growth factors and cytokines

Development of Epitope-Blocking ELISA for Universal Detection of Antibodies to Human H5N1 Influenza Viruses

10.1371/journal.pone.0004566PLoS ONE4

Structure-Guided Evolution of Potent and Selective CHK1 Inhibitors through Scaffold Morphing

Pyrazolopyridine inhibitors with low micromolar potency for CHK1 and good selectivity against CHK2 were previously identified by fragment-based screening. The optimization of the pyrazolopyridines to a series of potent and CHK1-selective isoquinolines demonstrates how fragment-growing and scaffold morphing strategies arising from a structure-based understanding of CHK1 inhibitor binding can be combined to successfully progress fragment-derived hit matter to compounds with activity in vivo. The challenges of improving CHK1 potency and selectivity, addressing synthetic tractability, and achieving novelty in the crowded kinase inhibitor chemical space were tackled by multiple scaffold morphing steps, which progressed through tricyclic pyrimido[2,3-b]azaindoles to N-(pyrazin-2-yl)pyrimidin-4-amines and ultimately to imidazo[4,5-c]pyridines and isoquinolines. A potent and highly selective isoquinoline CHK1 inhibitor (SAR-020106) was identified, which potentiated the efficacies of irinotecan and gemcitabine in SW620 human colon carcinoma xenografts in nude mice