Plasticity effects in subsequent simulations of car structures

In order to further reduce the weight of car components while at the same time\ud maintaining performance and safe life it is necessary to enhance the simulation process. This\ud is especially important for chassis parts which have not only a high dynamic load but are also\ud partly undamped. To reach this goal, the logical step is to couple the successive operations of\ud forming, assembly and virtual performance testing.\ud The objective is a complete determination of the mechanical state of the (sub-)assemblies.\ud It is therefore necessary to consider all forming and joining processes a part has previously\ud undergone and to consider them in the virtual model. This virtual model is ideally suited for\ud virtual prototyping (e.g. structural analysis, fatigue, crash) because the complete history of\ud every part is contained. In contrast to standard models, the changed thickness of sheet metal\ud parts and residual stresses due to forming and joining as well as the new material state at\ud every point are known prior to any external loading. This results in a more reliable prediction\ud of product performance.\ud Using a relatively simple part it is demonstrated how the performance of chassis parts\ud changes with the inclusion of plastic forming effects as compared to the exclusion of these\ud effects. The transfer of the results of the forming process to the comprehensive model is shown\ud first. Hereafter the model is subjected to static and dynamic external loads. The results are\ud compared to calculations that use a standard model and show clearly that the inclusion of the\ud plastic history has a significant influence on the product performance

Tool And Blank Interaction In The Cross-Die Forming Process

The deformation of the press and the forming tools during a deep drawing process is small. However, it has a significant influence on the formed product, since the draw-in is affected significantly by this deformation. This effect is demonstrated for the cross-die forming process. The process was simulated using the commercial code ABAQUS, comparing different models for the forming tools and blank. The simulated process behaves quite differently when rigid or deformable tools are applied. In the latter case, so-called tool-spacers absorb a significant part of the blankholder load, resulting in a stronger draw-in of the blank. In all cases, the results depended heavily on the blank element type and on numerical settings for the contact algorithm. These should be treated with great care when accurate results are required

Treatment related morbidity in breast cancer patients

Background: Sentinel lymph node biopsy (SLNB) was introduced for staging of the axilla to reduce the number of unnecessary axillary lymph node dissections (ALND’s) and proved to be an accurate and safe procedure to predict metastatic disease in clinically negative axillary lymph nodes. SLNB was expected to have less treatment related morbidity in comparison to ALND. In a multicenter prospective cohort study, long term upper-limb morbidity, perceived disabilities in activities of daily life (ADL) and quality of life (QOL) were assessed before and six weeks, 12 month and 24 month after SLNB or ALND for breast cancer. - \ud Methods: 204 patients with stage I/II breast cancer, mean age 55.6 years (sd: 11.6) entered the study and 181 patients (89%) could be evaluated after two years. Sixty-six patients (32%) underwent SLNB only, and 138 (68%) underwent a level I-II ALND. Reliable and valid assessment instruments were used for assessment of upper limb morbidity, ADL and QOL. Assessment included evaluation of shoulder range of motion, muscle strength, grip strength, pain, upper/forearm circumference, shoulder disability and activities of daily life (ADL) and Quality of Live. - \ud Results: Considerable treatment related upper-limb morbidity was observed. Significant (p<0.05) changes between before and up till two years after surgery were found in almost all assessments of shoulder function, ADL and several QOL subscales. Patients in the ALND group showed significant more changes in range of motion (ROM), grip strength, arm volume, ADL and QOL physical- and role functioning, pain and sleeplessness and arm symptoms compared to the SLNB group. Upper limb morbidity and associated disabilities in ADL are at worse in the early stage (first months) after surgical treatment. Concerning arm edema; in the ALND group arm volume increased significantly at 1 and 2 years follow up. Concerning QOL, significantly differences in mean change over the two years comparing SLNB with ALND were found for physical and role functioning and also for symptom items such as pain, insomnia (sleeplessness) and arm symptoms in favor of the SLNB group. QOL in the SLNB group was just improving in the 2 years after treatment whereas in de ALND group only emotional functioning and future perspective improved. Multivariate linear regression analysis showed that radiation therapy on the axilla is besides ALND an important factor in the prediction of impaired shoulder ROM and arm edema. Radiation therapy on the breast had no influence on shoulder ROM. - \ud Conclusion: 1. Significant treatment related short-term, middle-term and long-term upper limb morbidity and perceived disabilities in ADL and long-term reduction of QOL exist in breast cancer patients. 2. In the assessment of changes in upper limb function, ADL and QOL, ALND is the most frequent found predictor of deterioration. Additional radiation therapy on the axilla predicts a further decrease in shoulder ROM and arm edema. 3. Long-term upper limb morbidity is significantly correlated with disabilities in ADL and worsening of QOL

Algebraic and Topological Indices of Molecular Pathway Networks in Human Cancers

Protein-protein interaction networks associated with diseases have gained prominence as an area of research. We investigate algebraic and topological indices for protein-protein interaction networks of 11 human cancers derived from the Kyoto Encyclopedia of Genes and Genomes (KEGG) database. We find a strong correlation between relative automorphism group sizes and topological network complexities on the one hand and five year survival probabilities on the other hand. Moreover, we identify several protein families (e.g. PIK, ITG, AKT families) that are repeated motifs in many of the cancer pathways. Interestingly, these sources of symmetry are often central rather than peripheral. Our results can aide in identification of promising targets for anti-cancer drugs. Beyond that, we provide a unifying framework to study protein-protein interaction networks of families of related diseases (e.g. neurodegenerative diseases, viral diseases, substance abuse disorders).Comment: 15 pages, 4 figure