A detailed analysis of the stability and flipping dynamics of a delayed exclusive toggle switch is performed. We use forward flux sampling method combined with delayed stochastic simulation algorithm to get the statio...A detailed analysis of the stability and flipping dynamics of a delayed exclusive toggle switch is performed. We use forward flux sampling method combined with delayed stochastic simulation algorithm to get the stationary distribution function, the switching rate, and path- ways, as well as the transition state ensemble. Interestingly, under the influence of time delay, the stationary distribution corresponding to the stable states become narrower and the population in the transition region is significantly enhanced. In addition, the flipping rate increases monotonically with delay. Such findings demonstrate that time delay could reduce the stability of the bistable genetic switch dramatically. Furthermore, the transition pathways, characterized by the difference in the protein numbers and the state of operator, show larger discrepancy between the forward and backward switching process with increas- ing delay, indicating that transcriptional and translational delay can remarkably affect the flipping dynamics. Specifically, for the transition state, the difference in the probability of finding the operator site bound by the two different protein dimers is enlarged by delay, which further illustrates the crucial role of time delay on the stability and switching dynamics of genetic toggle switches.展开更多
This paper considers a model of a recursive neuron whose circuit the author finds interesting, not because of its financial possibility, but because of its surprising electrical behavior. Below, a recursive neuron is ...This paper considers a model of a recursive neuron whose circuit the author finds interesting, not because of its financial possibility, but because of its surprising electrical behavior. Below, a recursive neuron is modeled with excitatory and inhibitory triggering, and simulated using Win Spice. This model is shown to be capable of controlled toggling, and so promises energy-efficient, massively parallel computing.展开更多
After nearly a decade of application and investigation, a motion amplification device with viscous dampers for energy dissipation has been recognized as an effective solution to mitigate wind or seismic excitation, es...After nearly a decade of application and investigation, a motion amplification device with viscous dampers for energy dissipation has been recognized as an effective solution to mitigate wind or seismic excitation, especially for stiff structural systems. As a result of compensation of amplified motion, it has been proved that the efficiency of viscous damper largely depends on the motion amplification device configuration, particularly for device stiflhess. In this paper, a ＂scissor-jack＂ type of motion amplification device, called a ＂toggle brace damper＂ system, is studied. It is demonstrated that the efficiency of such a device reflected by its amplification factor is not merely a function of its geometric configuration, but is highly dependent on the support elements＇ stiffness as well, similar to the mechanism of a leverage arm. Accordingly, a mathematical model in terms of complex modulus of the viscous damper with consideration of the support brace＇s stiffness is established. The results indicate that the efficiency of the motion amplification device with viscous dampers significantly depends on the stiffness of the support elements. Other parameters, such as toggle brace configuration and damping values of the viscous damper, are studied and compared. As an application example, numerical analyses are conducted to study the dynamic performance of a 39-story office tower installed with toggle brace dampers constructed on soft soil in a reclaimed area, under a combined effect of the vortex shedding of an adjacent existing 52-story building and earthquakes. The results show that viscous dampers with a motion amplification system using a properly designed toggle brace device proved to be an effective solution to alleviate the external excitations.展开更多
Agonist binding of A2A adenosine receptor （A2AAR） shows protective effects against inflammatory and immune. Efforts are exerted in understanding the general mechanism and developing A2AAR selectively binding agonist...Agonist binding of A2A adenosine receptor （A2AAR） shows protective effects against inflammatory and immune. Efforts are exerted in understanding the general mechanism and developing A2AAR selectively binding agonists. Using molecular dynamics （MD） simula- tions, we have studied the interactions between A2AAR and its agonist （adenosine）, and analyzed the induced dynamic behaviors of the receptor. Key residues interacting with adenosine are identified： A63^2.61,I66^2.64,V84^3.32,L85^3.33,T88^3.36,F168^5.29,M177^5.38,L249^6.51,H250^6.52 and N253^6.55 interacting with adenosine with affinities larger than 0.5 kcal/mol. Moreover, no interaction between adenosine and L167^5.28 is observed, which supports our previous findings that L1675^5.28 is an antagonist specific binding reside. The dynamic be- haviors of agonist bound A2AAR are found to be different from apo-A2AAR in three typical functional switches： （i） tight ＂ionic lock＂ forms in adenosine-A2AAR, but it is in equilibrium between formation and breakage in apo-A2AAR; （ii） the ＂rotamer toggle switch＂, T88^3.36/F242^6.44/W246^6.48, adopted different rotameric conformations in adenosin-A2AAR and apo-A2AAR; （iii） adenosine-A2AAR has a flexible intracellular loop 2 （IC2） and s-helical IC3, while apo-A2AAR preferred s-helical IC2 and flexible IC3. Our results indicate that agonist binding induced different conformational rearrangements of these characteristic functional switches in adenosine-A2AAR and apo-A2AAR.展开更多
For training the present Neural Network(NN)models,the standard technique is to utilize decaying Learning Rates(LR).While the majority of these techniques commence with a large LR,they will decay multiple times over ti...For training the present Neural Network(NN)models,the standard technique is to utilize decaying Learning Rates(LR).While the majority of these techniques commence with a large LR,they will decay multiple times over time.Decaying has been proved to enhance generalization as well as optimization.Other parameters,such as the network’s size,the number of hidden layers,drop-outs to avoid overfitting,batch size,and so on,are solely based on heuristics.This work has proposed Adaptive Teaching Learning Based(ATLB)Heuristic to identify the optimal hyperparameters for diverse networks.Here we consider three architec-tures Recurrent Neural Networks(RNN),Long Short Term Memory(LSTM),Bidirectional Long Short Term Memory(BiLSTM)of Deep Neural Networks for classification.The evaluation of the proposed ATLB is done through the various learning rate schedulers Cyclical Learning Rate(CLR),Hyperbolic Tangent Decay(HTD),and Toggle between Hyperbolic Tangent Decay and Triangular mode with Restarts(T-HTR)techniques.Experimental results have shown the performance improvement on the 20Newsgroup,Reuters Newswire and IMDB dataset.展开更多
Jaw crusher is a kind of machine widely used in mining and aggregates industry,but it still has some shortcom- ings,such as liners wear,terrible power draw etc.The lack of research on material flow strongly limits the...Jaw crusher is a kind of machine widely used in mining and aggregates industry,but it still has some shortcom- ings,such as liners wear,terrible power draw etc.The lack of research on material flow strongly limits the design improvement. The size reduction of the jaw crusher relies on the moving jaw movement that is a kind of complicated swing.Based on the move- ment analysis of the moving jaw and the single particle breakage characters,the material flow is analyzed.The measure of the breakage force is carried out.Material flow analysis is partly confirmed by the experimental results and some new information is also learned from the crushing force distribution.The job on the material flow will be helpful to the jaw crusher design improve- ment.展开更多
In this research, a fast methodology to calculate the exact value of the average dynamic power consumption for CMOS combinational logic circuits is developed. The delay model used is the unit-delay model where all gat...In this research, a fast methodology to calculate the exact value of the average dynamic power consumption for CMOS combinational logic circuits is developed. The delay model used is the unit-delay model where all gates have the same propagation delay. The main advantages of this method over other techniques are its accuracy, as it is deterministic and it requires less computational effort compared to exhaustive simulation approaches. The methodology uses the Logic Pictures concept for obtaining the nodes’ toggle rates. The proposed method is applied to well-known circuits and the results are compared to exhaustive simulation and Monte Carlosimulation methods.展开更多
By means of total energy calculations within the framework of the local density approximation (LDA), the interactions between a silicon Si(001) surface and a scanning probe are investigated. The tip of the probe, comp...By means of total energy calculations within the framework of the local density approximation (LDA), the interactions between a silicon Si(001) surface and a scanning probe are investigated. The tip of the probe, comprising 4 Si atoms scans along the dimer lines above an asymmetric p(2 × 1) surface, at a distance where the chemical interaction between tip-surface is dominant and responsible for image resolution. At that distance, the tip causes the dimer to toggle when it scans above the lower atom of a dimer. The toggled dimers create an alternating pattern, where the immediately adjacent neighbours of a toggled dimer remain unchanged. After the tip has fully scanned across the p(2 × 1) surface, causes the dimers to arrange in a p(2 × 2) reconstruction, reproducing the images obtained in scanning probe experiments. Our modelling methodology includes simulations that reveal the energy input required to overcome the barrier to the onset of dimer toggling. The results show that the energy input to overcome this barrier is lower for the p(2 × 1) surface than that for the p(2 × 2) or c(4 × 2) surfaces.展开更多
We present a differential laser absorption spectroscopy(DLAS)system operating at 1550 nm for rapid and sensitive gas concentration measurements.A dual-wavelength toggling mechanism is presented,which significantly red...We present a differential laser absorption spectroscopy(DLAS)system operating at 1550 nm for rapid and sensitive gas concentration measurements.A dual-wavelength toggling mechanism is presented,which significantly reduces data processing,hence supporting a high update rate and data robustness against fast-changing environmental conditions.We showcase the ability to toggle between two wavelengths separated by 90 pm in 14μs and with minimal chirp(~1 pm),facilitating sensitive DLAS measurements at 8 kHz update rate.This performance is achieved by driving a 1550 nm diode laser with a modified square-wave current pulse,overcoming the thermal time constant limited wavelength-modulation response of the diode laser.A sensitive feedback mechanism ensures excellent long-term wavelength stability better than 1.4 pm peak-to-peak at 8 kHz toggling over 20 h,As a performance test,we measured the volumetric ratio(VMR)of hydrogen cyanide(HCN)gas in a fiber-coupled gas cell with lessthan 0.2%peak-to-peak variation over 20 h at 40 Hz.A best sensitivity in VMR of 8×10^(-6) was achieved at 25 ms integration time.The simplicity and high update rate of our system make it well-suited for gas monitoring in dynamic atmospheric and industrial environments.Further,it offers potential utility in applications requiring precise wavelength control,such as injection seeding of pulsed lasers.A simple analytical model is derived,which,in detail,supports the experimental results,hence offering a tool for future design optimization.展开更多
Background:Reports on the efficacy of modifications to the thread design of pedicle screws are scarce.The aim of the study was to investigate initial and early fixation of pedicle screws with a plasma-sprayed titanium...Background:Reports on the efficacy of modifications to the thread design of pedicle screws are scarce.The aim of the study was to investigate initial and early fixation of pedicle screws with a plasma-sprayed titanium coating and dual pitch in the pedicle region(dual pitch titanium-coated pedicle screw[DPTCPS])in a polyetheretherketone(PEEK)rod semi-rigid fixation system.Methods:Fifty-four sheep spine specimens and 64 sheep were used to investigate initial(“0-week”controls)and early(postoperative 6 months)fixation,respectively.Sheep were divided into dual pitch pedicle screw(DPPS),standard pitch pedicle screw(SPPS),DPTCPS,and standard pitch titanium-coated pedicle screw(SPTCPS)groups.Specimens/sheep were instrumented with four screws and two rods.Biomechanical evaluations were performed,and histology at the implant-bone interface was investigated.Results:At 0-week,mean axial pull-out strength was significantly higher for the DPTCPS and SPTCPS than the SPPS(557.0±25.2 vs.459.1±19.1 N,t=3.61,P<0.05;622.6±25.2 vs.459.1±19.1 N,t=3.43,P<0.05).On toggle-testing,the DPTCPS was significantly more resistant than the SPPS and SPTCPS(343.4±16.5 vs.237.5±12.9 N,t=3.52,P<0.05;343.4±16.5 vs.289.9±12.8 N,t=3.12,P<0.05;124.7±13.5 vs.41.9±4.3 cycles,t=2.18,P<0.05;124.7±13.5 vs.79.5±11.8 cycles,t=2.76,P<0.05).On cyclic loading,maximum displacement was significantly lower for the DPTCPS than the SPPS and SPTCPS(1.8±0.13 vs.3.76±0.19 mm,t=2.29,P<0.05;1.8±0.13 vs.2.46±10.20 mm,t=2.69,P<0.05).At post-operative 6 months,mean axial pull-out strength was significantly higher for the DPTCPS and SPTCPS than the SPPS(908.4±33.6 vs.646.5±59.4 N,t=3.34,P<0.05;925.9±53.9 vs.646.5±59.4 N,t=3.37,P<0.05).On toggle-testing,the DPTCPS was significantly more resistant than the SPPS and SPTCPS(496.9±17.9 vs.370.3±16.4 N,t=2.86,P<0.05;496.9±17.9 vs.414.1±12.8 N,t=2.74,P<0.05;249.1±11.0 vs.149.9±11.1 cycles,t=2.54,P<0.05;249.1±11.0 vs.199.8±7.2 cycles,t=2.61,P<0.05).On cyclic loading,maximum displacement was significantly lower for the DPTCPS than the SPPS and SPTCPS(0.96±0.11 vs.2.39±0.14 mm,t=2.57,P<0.05;0.96±0.11 vs.1.82±0.12 mm,t=2.73,P<0.05).Resistance to toggle testing(370.3±16.4 vs.414.1±12.8 N,t=3.29,P<0.05;149.9±11.1 vs.199.8±7.2 cycles,t=2.97,P<0.05)was significantly lower and maximum displacement in cyclic loading(2.39±0.14 vs.1.82±0.12 mm;t=3.06,P<0.05)was significantly higher for the SPTCPS than the DPTCPS.Bone-to-implant contact was significantly increased for the DPTCPS compared to the SPPS(58.3%±7.0%vs.36.5%±4.4%,t=2.74,P<0.05);there was no inflammatory reaction or degradation of coated particles.Conclusion:DPTCPSs might have stronger initial and early fixation in a PEEK rod semi-rigid fixation system.展开更多
Taking the famous genetic toggle switch as an example,we numerically investigated the effect of noise on bistability.We found that extrinsic noise resulting from stochastic fluctuations in synthesis and degradation ra...Taking the famous genetic toggle switch as an example,we numerically investigated the effect of noise on bistability.We found that extrinsic noise resulting from stochastic fluctuations in synthesis and degradation rates and from the environmental fluctuation in gene regulatory processes can induce coherent switch,and that there is an optimal noise intensity such that the noise not only can induce this switch,but also can amplify a weak input signal.In addition,we found that the intrinsic noise introduced through the Poisson τ-leap algorithm cannot induce such a switch.展开更多
文摘A detailed analysis of the stability and flipping dynamics of a delayed exclusive toggle switch is performed. We use forward flux sampling method combined with delayed stochastic simulation algorithm to get the stationary distribution function, the switching rate, and path- ways, as well as the transition state ensemble. Interestingly, under the influence of time delay, the stationary distribution corresponding to the stable states become narrower and the population in the transition region is significantly enhanced. In addition, the flipping rate increases monotonically with delay. Such findings demonstrate that time delay could reduce the stability of the bistable genetic switch dramatically. Furthermore, the transition pathways, characterized by the difference in the protein numbers and the state of operator, show larger discrepancy between the forward and backward switching process with increas- ing delay, indicating that transcriptional and translational delay can remarkably affect the flipping dynamics. Specifically, for the transition state, the difference in the probability of finding the operator site bound by the two different protein dimers is enlarged by delay, which further illustrates the crucial role of time delay on the stability and switching dynamics of genetic toggle switches.
基金the National Basic Research Program of China，the National Natural Science Foundation of China，the Fundamental Research Funds for the Central Universities
文摘This paper considers a model of a recursive neuron whose circuit the author finds interesting, not because of its financial possibility, but because of its surprising electrical behavior. Below, a recursive neuron is modeled with excitatory and inhibitory triggering, and simulated using Win Spice. This model is shown to be capable of controlled toggling, and so promises energy-efficient, massively parallel computing.
文摘After nearly a decade of application and investigation, a motion amplification device with viscous dampers for energy dissipation has been recognized as an effective solution to mitigate wind or seismic excitation, especially for stiff structural systems. As a result of compensation of amplified motion, it has been proved that the efficiency of viscous damper largely depends on the motion amplification device configuration, particularly for device stiflhess. In this paper, a ＂scissor-jack＂ type of motion amplification device, called a ＂toggle brace damper＂ system, is studied. It is demonstrated that the efficiency of such a device reflected by its amplification factor is not merely a function of its geometric configuration, but is highly dependent on the support elements＇ stiffness as well, similar to the mechanism of a leverage arm. Accordingly, a mathematical model in terms of complex modulus of the viscous damper with consideration of the support brace＇s stiffness is established. The results indicate that the efficiency of the motion amplification device with viscous dampers significantly depends on the stiffness of the support elements. Other parameters, such as toggle brace configuration and damping values of the viscous damper, are studied and compared. As an application example, numerical analyses are conducted to study the dynamic performance of a 39-story office tower installed with toggle brace dampers constructed on soft soil in a reclaimed area, under a combined effect of the vortex shedding of an adjacent existing 52-story building and earthquakes. The results show that viscous dampers with a motion amplification system using a properly designed toggle brace device proved to be an effective solution to alleviate the external excitations.
文摘Agonist binding of A2A adenosine receptor （A2AAR） shows protective effects against inflammatory and immune. Efforts are exerted in understanding the general mechanism and developing A2AAR selectively binding agonists. Using molecular dynamics （MD） simula- tions, we have studied the interactions between A2AAR and its agonist （adenosine）, and analyzed the induced dynamic behaviors of the receptor. Key residues interacting with adenosine are identified： A63^2.61,I66^2.64,V84^3.32,L85^3.33,T88^3.36,F168^5.29,M177^5.38,L249^6.51,H250^6.52 and N253^6.55 interacting with adenosine with affinities larger than 0.5 kcal/mol. Moreover, no interaction between adenosine and L167^5.28 is observed, which supports our previous findings that L1675^5.28 is an antagonist specific binding reside. The dynamic be- haviors of agonist bound A2AAR are found to be different from apo-A2AAR in three typical functional switches： （i） tight ＂ionic lock＂ forms in adenosine-A2AAR, but it is in equilibrium between formation and breakage in apo-A2AAR; （ii） the ＂rotamer toggle switch＂, T88^3.36/F242^6.44/W246^6.48, adopted different rotameric conformations in adenosin-A2AAR and apo-A2AAR; （iii） adenosine-A2AAR has a flexible intracellular loop 2 （IC2） and s-helical IC3, while apo-A2AAR preferred s-helical IC2 and flexible IC3. Our results indicate that agonist binding induced different conformational rearrangements of these characteristic functional switches in adenosine-A2AAR and apo-A2AAR.
文摘For training the present Neural Network(NN)models,the standard technique is to utilize decaying Learning Rates(LR).While the majority of these techniques commence with a large LR,they will decay multiple times over time.Decaying has been proved to enhance generalization as well as optimization.Other parameters,such as the network’s size,the number of hidden layers,drop-outs to avoid overfitting,batch size,and so on,are solely based on heuristics.This work has proposed Adaptive Teaching Learning Based(ATLB)Heuristic to identify the optimal hyperparameters for diverse networks.Here we consider three architec-tures Recurrent Neural Networks(RNN),Long Short Term Memory(LSTM),Bidirectional Long Short Term Memory(BiLSTM)of Deep Neural Networks for classification.The evaluation of the proposed ATLB is done through the various learning rate schedulers Cyclical Learning Rate(CLR),Hyperbolic Tangent Decay(HTD),and Toggle between Hyperbolic Tangent Decay and Triangular mode with Restarts(T-HTR)techniques.Experimental results have shown the performance improvement on the 20Newsgroup,Reuters Newswire and IMDB dataset.
文摘Jaw crusher is a kind of machine widely used in mining and aggregates industry,but it still has some shortcom- ings,such as liners wear,terrible power draw etc.The lack of research on material flow strongly limits the design improvement. The size reduction of the jaw crusher relies on the moving jaw movement that is a kind of complicated swing.Based on the move- ment analysis of the moving jaw and the single particle breakage characters,the material flow is analyzed.The measure of the breakage force is carried out.Material flow analysis is partly confirmed by the experimental results and some new information is also learned from the crushing force distribution.The job on the material flow will be helpful to the jaw crusher design improve- ment.
文摘In this research, a fast methodology to calculate the exact value of the average dynamic power consumption for CMOS combinational logic circuits is developed. The delay model used is the unit-delay model where all gates have the same propagation delay. The main advantages of this method over other techniques are its accuracy, as it is deterministic and it requires less computational effort compared to exhaustive simulation approaches. The methodology uses the Logic Pictures concept for obtaining the nodes’ toggle rates. The proposed method is applied to well-known circuits and the results are compared to exhaustive simulation and Monte Carlosimulation methods.
文摘By means of total energy calculations within the framework of the local density approximation (LDA), the interactions between a silicon Si(001) surface and a scanning probe are investigated. The tip of the probe, comprising 4 Si atoms scans along the dimer lines above an asymmetric p(2 × 1) surface, at a distance where the chemical interaction between tip-surface is dominant and responsible for image resolution. At that distance, the tip causes the dimer to toggle when it scans above the lower atom of a dimer. The toggled dimers create an alternating pattern, where the immediately adjacent neighbours of a toggled dimer remain unchanged. After the tip has fully scanned across the p(2 × 1) surface, causes the dimers to arrange in a p(2 × 2) reconstruction, reproducing the images obtained in scanning probe experiments. Our modelling methodology includes simulations that reveal the energy input required to overcome the barrier to the onset of dimer toggling. The results show that the energy input to overcome this barrier is lower for the p(2 × 1) surface than that for the p(2 × 2) or c(4 × 2) surfaces.
文摘We present a differential laser absorption spectroscopy(DLAS)system operating at 1550 nm for rapid and sensitive gas concentration measurements.A dual-wavelength toggling mechanism is presented,which significantly reduces data processing,hence supporting a high update rate and data robustness against fast-changing environmental conditions.We showcase the ability to toggle between two wavelengths separated by 90 pm in 14μs and with minimal chirp(~1 pm),facilitating sensitive DLAS measurements at 8 kHz update rate.This performance is achieved by driving a 1550 nm diode laser with a modified square-wave current pulse,overcoming the thermal time constant limited wavelength-modulation response of the diode laser.A sensitive feedback mechanism ensures excellent long-term wavelength stability better than 1.4 pm peak-to-peak at 8 kHz toggling over 20 h,As a performance test,we measured the volumetric ratio(VMR)of hydrogen cyanide(HCN)gas in a fiber-coupled gas cell with lessthan 0.2%peak-to-peak variation over 20 h at 40 Hz.A best sensitivity in VMR of 8×10^(-6) was achieved at 25 ms integration time.The simplicity and high update rate of our system make it well-suited for gas monitoring in dynamic atmospheric and industrial environments.Further,it offers potential utility in applications requiring precise wavelength control,such as injection seeding of pulsed lasers.A simple analytical model is derived,which,in detail,supports the experimental results,hence offering a tool for future design optimization.
文摘Background:Reports on the efficacy of modifications to the thread design of pedicle screws are scarce.The aim of the study was to investigate initial and early fixation of pedicle screws with a plasma-sprayed titanium coating and dual pitch in the pedicle region(dual pitch titanium-coated pedicle screw[DPTCPS])in a polyetheretherketone(PEEK)rod semi-rigid fixation system.Methods:Fifty-four sheep spine specimens and 64 sheep were used to investigate initial(“0-week”controls)and early(postoperative 6 months)fixation,respectively.Sheep were divided into dual pitch pedicle screw(DPPS),standard pitch pedicle screw(SPPS),DPTCPS,and standard pitch titanium-coated pedicle screw(SPTCPS)groups.Specimens/sheep were instrumented with four screws and two rods.Biomechanical evaluations were performed,and histology at the implant-bone interface was investigated.Results:At 0-week,mean axial pull-out strength was significantly higher for the DPTCPS and SPTCPS than the SPPS(557.0±25.2 vs.459.1±19.1 N,t=3.61,P<0.05;622.6±25.2 vs.459.1±19.1 N,t=3.43,P<0.05).On toggle-testing,the DPTCPS was significantly more resistant than the SPPS and SPTCPS(343.4±16.5 vs.237.5±12.9 N,t=3.52,P<0.05;343.4±16.5 vs.289.9±12.8 N,t=3.12,P<0.05;124.7±13.5 vs.41.9±4.3 cycles,t=2.18,P<0.05;124.7±13.5 vs.79.5±11.8 cycles,t=2.76,P<0.05).On cyclic loading,maximum displacement was significantly lower for the DPTCPS than the SPPS and SPTCPS(1.8±0.13 vs.3.76±0.19 mm,t=2.29,P<0.05;1.8±0.13 vs.2.46±10.20 mm,t=2.69,P<0.05).At post-operative 6 months,mean axial pull-out strength was significantly higher for the DPTCPS and SPTCPS than the SPPS(908.4±33.6 vs.646.5±59.4 N,t=3.34,P<0.05;925.9±53.9 vs.646.5±59.4 N,t=3.37,P<0.05).On toggle-testing,the DPTCPS was significantly more resistant than the SPPS and SPTCPS(496.9±17.9 vs.370.3±16.4 N,t=2.86,P<0.05;496.9±17.9 vs.414.1±12.8 N,t=2.74,P<0.05;249.1±11.0 vs.149.9±11.1 cycles,t=2.54,P<0.05;249.1±11.0 vs.199.8±7.2 cycles,t=2.61,P<0.05).On cyclic loading,maximum displacement was significantly lower for the DPTCPS than the SPPS and SPTCPS(0.96±0.11 vs.2.39±0.14 mm,t=2.57,P<0.05;0.96±0.11 vs.1.82±0.12 mm,t=2.73,P<0.05).Resistance to toggle testing(370.3±16.4 vs.414.1±12.8 N,t=3.29,P<0.05;149.9±11.1 vs.199.8±7.2 cycles,t=2.97,P<0.05)was significantly lower and maximum displacement in cyclic loading(2.39±0.14 vs.1.82±0.12 mm;t=3.06,P<0.05)was significantly higher for the SPTCPS than the DPTCPS.Bone-to-implant contact was significantly increased for the DPTCPS compared to the SPPS(58.3%±7.0%vs.36.5%±4.4%,t=2.74,P<0.05);there was no inflammatory reaction or degradation of coated particles.Conclusion:DPTCPSs might have stronger initial and early fixation in a PEEK rod semi-rigid fixation system.
基金the National Distinguished PhD Dissertations(200521)the National Natural Science Foundation of China(Grant No.60736208)
文摘Taking the famous genetic toggle switch as an example,we numerically investigated the effect of noise on bistability.We found that extrinsic noise resulting from stochastic fluctuations in synthesis and degradation rates and from the environmental fluctuation in gene regulatory processes can induce coherent switch,and that there is an optimal noise intensity such that the noise not only can induce this switch,but also can amplify a weak input signal.In addition,we found that the intrinsic noise introduced through the Poisson τ-leap algorithm cannot induce such a switch.
