Regulation of chromosome segregation in Drosophila meiosis

Sister-chromatid cohesion is maintained by Cohesin complex. Separase releases the cohesion through the cleavage of the kleisin subunit of Cohesin complex. Separase is regulated by its inhibitor, Securin/Pim. These processes are well studied in mitosis but little is known for meiosis. I found that Separase is required for the proper separation of homologous chromosomes and sister chromatids in Drosophila meiosis. Its function is inhibited by Securin/Pim during the process. I showed that the common kleisin subunit, Rad21, is not likely to be the meiotic target of Separase and that Rad21 and another common Cohesin component, SMC3/CAP, does not contribute to sister-chromatid cohesion in meiosis. Therefore Drosophila meiosis may use novel protein(s) to mediate cohesion. I also found that Rad21 contributes to the sister-chromatid cohesion in the polar body and Separase is responsible for the release of this cohesion at the arm region under the control of Securin/Pim

Container vehicle-truss bridge coupled vibration analysis and structural safety assessment under stochastic excitation

The container vehicle-truss bridge coupled vibration greatly affects the automated container terminals’ (ACT) structural safety and handling efficiency. Using free-interface component mode synthesis (CMS) method, the coupled vibration time-domain responses, under self-excitation including track irregularity and hunting movement as well as environmental excitations such as wind and seismic load, were obtained. Stochastic simulation of track irregularity and fluctuating wind time-history was generated based on the numerical simulation method of multidimensional homogeneous process. A scale model test was introduced to validate the CMS method’s effectiveness and vehicle speed’s influence on coupled vibration response. In this case, the vehicle-bridge vertical vibration is caused mainly by the vehicle moving load, and self-excitation is a major factor. Wind, seismic load will greatly enhance the lateral vibration. And the sensitivity of the response to the seismic load is greater than operational wind load. As vehicle velocity, fluctuating wind mean velocity or ground motion intensity increase, the responses increase. Then, the structural safety, running safety and stability were assessed by the indicators such as deflection-span ratio, acceleration response etc., under wind load only and under operational wind and ground motion excited simultaneously. It is proved by both prototype simulation and model test results that, lead rubber bearing (LRB) can effectively reduce the acceleration response of both the vehicle and the bridge; therefore, can raise vehicle speed limits for structural and running safety

Eliminating interactions between non-neighboring qubits in the preparation of cluster states in quantum molecules

We propose a scheme to eliminate the effect of non-nearest-neighbor qubits in preparing cluster state with double-dot molecules. As the interaction Hamiltonians between qubits are Ising-model and mutually commute, we can get positive and negative effective interactions between qubits to cancel the effect of non-nearest-neighbor qubits by properly changing the electron charge states of each quantum dot molecule. The total time for the present multi-step cluster state preparation scheme is only doubled for one-dimensional qubit chain and tripled for two-dimensional qubit array comparing with the time of previous protocol leaving out the non-nearest-neighbor interactions.Comment: 5 pages, 4 figures, 2 table