A bone cell population dynamics model for cor- tical bone remodeling under mechanical stimulus is devel- oped in this paper. The external experiments extracted from the literature which have not been used in the creat...A bone cell population dynamics model for cor- tical bone remodeling under mechanical stimulus is devel- oped in this paper. The external experiments extracted from the literature which have not been used in the creation of the model are used to test the validity of the model. Not only can the model compare reasonably well with these ex- perimental results such as the increase percentage of final values of bone mineral content （BMC） and bone fracture en- ergy （BFE） among different loading schemes （which proves the validity of the model）, but also predict the realtime devel- opment pattern of BMC and BFE, as well as the dynamics of osteoblasts （OBA）, osteoclasts （OCA）, nitric oxide （NO） and prostaglandin E2 （PGE2） for each loading scheme, which can hardly be monitored through experiment. In conclusion, the model is the first of its kind that is able to provide an in- sight into the quantitative mechanism of bone remodeling at cellular level by which bone cells are activated by mechan- ical stimulus in order to start resorption/formation of bone mass. More importantly, this model has laid a solid foun- dation based on which future work such as systemic control theory analysis of bone remodeling under mechanical stimu- lus can be investigated. The to-be identified control mecha- nism will help to develop effective drugs and combined non- pharmacological therapies to combat bone loss pathologies. Also this deeper understanding of how mechanical forces quantitatively interact with skeletal tissue is essential for the generation of bone tissue for tissue replacement purposes in tissue engineering.展开更多
Incorporation of the Barnegat Bay into the US National Estuary Program has triggered collection and collation of basic data sets appropriate to estuarine management. Gathering of water quality and quantity as well as ...Incorporation of the Barnegat Bay into the US National Estuary Program has triggered collection and collation of basic data sets appropriate to estuarine management. Gathering of water quality and quantity as well as basic geological data is adding to the knowledge of the complexity of the bay. An ongoing program of systematic sampling of bottom sediments in the large bay and intense sampling in the many micro-estuaries along the mainland margin is demonstrating the presence of localized mor-pho-sedimentological units related to the interaction of the fluvial, tidal, and wave processes active in the bay. Mean grain sizes and standard deviation measures assist in the development of signatures of bottom sediment types.展开更多
The extended finite element method is used to analyze a plate with two parallel edge cracks impacted by a cylindrical projectile. The influence of the impact speed, crack length, plate thickness and notch tip radius o...The extended finite element method is used to analyze a plate with two parallel edge cracks impacted by a cylindrical projectile. The influence of the impact speed, crack length, plate thickness and notch tip radius on the crack initiation and propagation is studied. Dynamics equations are solved by an implicit time integration scheme which is unconditionally stable. Very good agreement is achieved between numerical predictions and experimental results. The critical velocity of the crack initiation under different conditions is examined. The influence of the crack length is greater than that of the impact speed, plate thickness and notch tip radius.展开更多
文摘A bone cell population dynamics model for cor- tical bone remodeling under mechanical stimulus is devel- oped in this paper. The external experiments extracted from the literature which have not been used in the creation of the model are used to test the validity of the model. Not only can the model compare reasonably well with these ex- perimental results such as the increase percentage of final values of bone mineral content （BMC） and bone fracture en- ergy （BFE） among different loading schemes （which proves the validity of the model）, but also predict the realtime devel- opment pattern of BMC and BFE, as well as the dynamics of osteoblasts （OBA）, osteoclasts （OCA）, nitric oxide （NO） and prostaglandin E2 （PGE2） for each loading scheme, which can hardly be monitored through experiment. In conclusion, the model is the first of its kind that is able to provide an in- sight into the quantitative mechanism of bone remodeling at cellular level by which bone cells are activated by mechan- ical stimulus in order to start resorption/formation of bone mass. More importantly, this model has laid a solid foun- dation based on which future work such as systemic control theory analysis of bone remodeling under mechanical stimu- lus can be investigated. The to-be identified control mecha- nism will help to develop effective drugs and combined non- pharmacological therapies to combat bone loss pathologies. Also this deeper understanding of how mechanical forces quantitatively interact with skeletal tissue is essential for the generation of bone tissue for tissue replacement purposes in tissue engineering.
基金Support for this project was provided by The Trust for Public Lands, the New Jersey Sea Grant Program, and the Institute of Marine and Coastal Sciences, Rutgers University. Field and laboratory assistance was ably provided by Natalie Pitchford, Adam Levy
文摘Incorporation of the Barnegat Bay into the US National Estuary Program has triggered collection and collation of basic data sets appropriate to estuarine management. Gathering of water quality and quantity as well as basic geological data is adding to the knowledge of the complexity of the bay. An ongoing program of systematic sampling of bottom sediments in the large bay and intense sampling in the many micro-estuaries along the mainland margin is demonstrating the presence of localized mor-pho-sedimentological units related to the interaction of the fluvial, tidal, and wave processes active in the bay. Mean grain sizes and standard deviation measures assist in the development of signatures of bottom sediment types.
基金supported by the National Natural Science Foundation of China(Nos.11272096 and 11472086)the Research Fund for the Doctoral Program of Higher Education of China(No.20112304110015)
文摘The extended finite element method is used to analyze a plate with two parallel edge cracks impacted by a cylindrical projectile. The influence of the impact speed, crack length, plate thickness and notch tip radius on the crack initiation and propagation is studied. Dynamics equations are solved by an implicit time integration scheme which is unconditionally stable. Very good agreement is achieved between numerical predictions and experimental results. The critical velocity of the crack initiation under different conditions is examined. The influence of the crack length is greater than that of the impact speed, plate thickness and notch tip radius.
