Finite element analysis of porously punched prosthetic short stem virtually designed for simulative uncemented hip arthroplasty

Background: There is no universal hip implant suitably fills all femoral types, whether prostheses of porous short-stem suitable for Hip Arthroplasty is to be measured scientifically. Methods: Ten specimens of femurs scanned by CT were input onto Mimics to rebuild 3D models; their *stl format dataset were imported into Geomagic-Studio for simulative osteotomy; the generated *.igs dataset were interacted by UG to fit solid models; the prosthesis were obtained by the same way from patients, and bored by punching bears designed by Pro-E virtually; cements between femora and prosthesis were extracted by deleting prosthesis; in HyperMesh, all compartments were assembled onto four artificial joint style as: (a) cemented long-stem prosthesis; (b) porous long-stem prosthesis; (c) cemented short-stem prosthesis; (d) porous short-stem prosthesis. Then, these numerical models of Finite Element Analysis were exported to AnSys for numerical solution. Results: Observed whatever from femur or prosthesis or combinational femora-prostheses, “Kruskal-Wallis” value p > 0.05 demonstrates that displacement of (d) ≈ (a) ≈ (b) ≈ (c) shows nothing different significantly by comparison with 600 N load. If stresses are tested upon prosthesis, (d) ≈ (a) ≈ (b) ≈ (c) is also displayed; if upon femora, (d) ≈ (a) ≈ (b) < (c) is suggested; if upon integral joint, (d) ≈ (a) < (b) < (c) is presented. Conclusions: Mechanically, these four sorts of artificial joint replacement are stabilized in quantity. Cemented short-stem prostheses present the biggest stress, while porous short-stem & cemented long-stem designs are equivalently better than porous long-stem prostheses and alternatives for femoral-head replacement. The preferred design of those two depends on clinical conditions. The cemented long-stem is favorable for inactive elders with osteoporosis, and porously punched cementless short-stem design is suitable for patients with osteoporosis, while the porously punched cementless short-stem is favorable for those with a cement allergy. Clinically, the strength of this study is to enable preoperative strategy to provide acute correction and decrease procedure time

A New Approach to Constrain Black Hole Spins in Active Galaxies Using Optical Reverberation Mapping

A tight relation between the size of the broad-line region (BLR) and optical luminosity has been established in about 50 active galactic nuclei studied through reverberation mapping of the broad Hbeta emission line. The R_blr-L relation arises from simple photoionization considerations. Using a general relativistic model of an optically thick, geometrically thin accretion disk, we show that the ionizing luminosity jointly depends on black hole mass, accretion rate, and spin. The non-monotonic relation between the ionizing and optical luminosity gives rise to a complicated relation between the BLR size and the optical luminosity. We show that the reverberation lag of Hbeta to the varying continuum depends very sensitively to black hole spin. For retrograde spins, the disk is so cold that there is a deficit of ionizing photons in the BLR, resulting in shrinkage of the hydrogen ionization front with increasing optical luminosity, and hence shortened Hbeta lags. This effect is specially striking for luminous quasars undergoing retrograde accretion, manifesting in strong deviations from the canonical R_blr-L relation. This could lead to a method to estimate black hole spins of quasars and to study their cosmic evolution. At the same time, the small scatter of the observed R_blr-L relation for the current sample of reverberation-mapped active galaxies implies that the majority of these sources have rapidly spinning black holes.Comment: 6 pages, 5 figures, to appear in ApJ

Neuroprotective effects of lomerizine on retinal ganglion cells in the diet-induced obese C57BL/6J mice

AIM: To research the neuroprotective effects of lomerizine(LOM)on retinal ganglion cells(RGCs)in the diet-induced obese C57BL/6J mice. <p>METHODS: Fifty-four mice were randomly divided into two groups which were fed a high-fat diet for 19wk. One group mice were lavaged LOM by the dosage of 80mg/kg daily at the same time. The obese mice were selected and divided into diet-induced obesity(DIO)group, diet-induced obesity and lomerizine(DIO+LOM)group. The mice in the control(CON)group were fed a basal diet. The ultrastructural changes of RGCs were detected by transmission electron microscope. The cellular apoptosis was detected by TUNEL. The laser scanning confocal microscope was used to measure intracellular calcium ion concentration. <p>RESULTS: Compared with the CON group, the RGCs in DIO group showed smaller and condensation of nuclear chromatin and increased electron density of the cytoplasm, whereas the changes in DIO+LOM mice were obviously diminished. TUNEL staining showed that the number of apoptosis cells in the ganglion cell layer(GCL)increased in DIO group and the percentage of apoptotic cells was much higher than that in the CON groups(<i>P</i><0.01). The DIO+LOM group mice showed fewer apoptosis cells and the percentage of apoptotic cells in this group were significantly decreased than the DIO mice(<i>P</i><0.05). The Laser scanning confocal microscope detection showed Ca²⁺ staining intensity of RGCs in DIO group increased and its staining intensity ratio was significantly higher than in CON group(<i>P</i><0.01), the Ca²⁺ staining intensity and its staining intensity ratio in DIO+LOM group were significantly decreased than the DIO group(<i>P</i><0.01). <p>CONCLUSION: Lomerizine has neuroprotective effects on damage of retinal ganglion cells in diet-induced obesity mice, which may be related to the attenuation of intracellular Ca²⁺ overload

Hypersonic Vehicles Profile-Following Based on LQR Design Using Time-Varying Weighting Matrices

In the process of applying linear quadratic regulator (LQR) to solve aerial vehicle reentry reference trajectory guidance, to obtain better profile-following performance, the parameters of the aerial vehicle system can be used to calculate weighting matrices according to the Bryson principle. However, the traditional method is not applicable to various disturbances in hypersonic vehicles (HSV) which have particular dynamic characteristics. By calculating the weighting matrices constructed based on Bryson principle using time-varying parameters, a novel time-varying LQR design method is proposed to deal with the various disturbances in HSV reentry profile-following. Different from the previous approaches, the current states of the flight system are employed to calculate the parameters in weighting matrices. Simulation results are given to demonstrate that using the proposed approach in this chapter, performance of HSV profile-following can be improved significantly, and stronger robustness against different disturbances can be obtained