Search PubMed⌕ Search
Home/Archive/PubMed

PubMed · 15458057

Soft-tissue simulation using LEM--Long Elements Method.

Remis Balaniuk
View original source ↗Export metadata ↓

Abstract

This paper discusses the use of the Long Elements Method--LEM in soft tissue modeling and surgery simulation. The LEM is a new method for real time, physically based, dynamic simulation of deformable objects, based on a new meshing strategy, using long elements. The method uses a combination of static (state-less) and dynamic approaches to simulate deformations and dynamics, obtaining a higher degree of compliance per time step. Global deformations that conserve volume and are convincingly compliant are obtained. Models are defined using bulk material properties. Elastic and plastic deformations can be simulated. The real time performance of the method and its intrinsic properties of volume conservation, modeling based in material properties and simpler meshing make it particularly attractive for soft tissue modeling and surgery simulation.

Explore related subjects

Biomechanical PhenomenaComputer GraphicsComputer SimulationConnective TissueGeneral SurgeryHumansImaging, Three-DimensionalSurgery, Computer-AssistedTouchUser-Computer InterfaceJournal Article

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Remis Balaniuk. 2002. Soft-tissue simulation using LEM--Long Elements Method.. https://pubmed.ncbi.nlm.nih.gov/15458057/

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related citations

PubMed2006

Biomechanical investigation of the effect of high hydrostatic pressure treatment on the mechanical properties of human bone.

Several methods are available for reconstruction of bone defects due to malignant tumors. To extracorporally devitalize resected tumor-bearing bone segments two methods, that is, extracorporal irradiation or autoclaving, are available up to now. However, both methods have substantial disadvantages like decrease of bone's mechanical strength. To develop an alternative method for tumor inactivation in skeletal segments, high hydrostatic pressure (HHP) was applied. Previous investigations have shown that human normal and tumor cell lines as well as tumor-afflicted human bone specimens were irreversibly damaged at 350 MPa when subjected to HHP. This study was aimed to examine the alterations of biomechanical properties of human bone after exposure to HHP. Trabecular and cortical bone specimens were harvested from six pair of fresh-frozen human cadaveric femora. The bone specimens from one side were exposed to different pressure values of 300 or 600 MPa over 10 min. Bone samples from the contralateral sites were used as untreated controls. Biomechanical properties were investigated by a quasi-static compression test for trabecular specimens and by a quasi-static four-point bending test for cortical specimens, respectively. Biomechanical properties of the cortical and trabecular bone did not decrease after exposure to 300 MPa regarding the testing parameters Young's modulus and ultimate strength (200.7 +/- 38.7 MPa for HHP treated cortical bone versus 186.5 +/- 34.3 MPa for the untreated control group). After pressure treatment at 600 MPa Young's modulus and ultimate strength respectively remained almost unchanged in trabecular bone and were reduced about 15% in cortical bone (p < 0.001 and p =0.002, respectively). We anticipate that in orthopedic surgery HHP can serve as a novel, promising methodical approach for tumor cell inactivation, which occurs at pressure levels of about 300 MPa. Thereby immediate reimplantation of treated bone segments by preservation of the essential biomechanical properties of bone could become possible. Even after HHP treatment at 600 MPa the strength of bone only decreases up to 15%.

Biomechanical Phenomena↗
PubMed2005

Relations between occupational, psychosocial and individual factors and three different categories of back disorder among supermarket workers.

OBJECTIVES: Up-to-date store-wide studies regarding low back pain (LBP) among supermarket/hypermarket workers are lacking. We investigated 12-month store-wide prevalence of different categories of LBP and possible associated biomechanical, individual/psychosocial risk factors across a large supermarket/hypermarket chain. METHODS: We performed a cross-sectional study of 3,702 subjects working in a group of small/medium-sized supermarkets (n=100) and large hypermarkets (n=7) belonging to a single chain in central-northern Italy applying established ergonomics/job-satisfaction policies. Data regarding the various departments were collected by a medical check-list, physical examination and questionnaire-all conducted by qualified physicians--and were analyzed in relation to a comprehensive biomechanical risk analysis. RESULTS: The overall 12-month prevalence of LBP in our sample (with a 82% response rate) was 34.5% (36.6% for females and 30.7% for males), with few differences being found between supermarkets and hypermarkets. Different types of LBP showed significant associations with stress-related psychosomatic symptoms, but not with job satisfaction (which was high). CONCLUSIONS: These encouraging data provide relevant information regarding workers operating in supermarkets/hypermarkets with an active commitment to ergonomic and job-satisfaction policies.

Biomechanical Phenomena↗
PubMed2005

Why forces between proteins follow different Hofmeister series for pH above and below pI.

The relative effectiveness of different anions in crystallizing proteins follows a reversed Hofmeister sequence for pH pI. The phenomenon has been known almost since Hofmeister's original work but it has not been understood. It is here given a theoretical explanation. Classical electrolyte and double layer theory deals only with electrostatic forces acting between ions and proteins. Hydration and hydration interactions are dealt with usually only in terms of assumed hard core models. But there are, at and above biological salt concentrations, other non-electrostatic (NES) ion-specific forces acting that are ignored in such modeling. Such electrodynamic fluctuation forces are also responsible for ion-specific hydration. These missing forces are variously comprehended under familiar but generally unquantified terms, typically, hydration, hydrogen bonding, pi-electron-cation interactions, dipole-dipole, dipole-induced dipole and induced dipole-induced dipole forces and so on. The many important body electrodynamic fluctuation force contributions are accessible from extensions of Lifshitz theory from which, with relevant dielectric susceptibility data on solutions as a function of frequency, the forces can be extracted quantitatively, at least in principle. The classical theories of colloid science that miss such contributions do not account for a whole variety of ion-specific phenomena. Numerical results that include these non-electrostatic forces are given here for model calculations of the force between two model charge-regulated hen-egg-white protein surfaces. The surfaces are chosen to carry the same charge groups and charge density as the protein. What emerges is that for pH pI (where anions are co-ions) the forces increase in the order NaCl<NaI<NaSCN. This is in excellent agreement with both solubility experiments and experiments using SAXS. The results are also consistent with cation effects observed in protein solutions. Our results may provide some insights into a long-standing problem in solution chemistry and biology.

Biomechanical Phenomena↗