小鼠慢性应激性抑郁症易感品系筛选及其易感机制初步研究

Objective: To screen mouse strain that susceptive to chronic unpredicted mild stress (CUMS) and preliminarily research its susceptive mechanism. Methods: KM, ICR, BABL/c and C57BL/6 mice were used to establish CUMS depression model. Body weight, sucrose preference test (SPT), open field test (FT) were used to evaluate the sensitivity of mice to CUMS. Hippocampal levels of glucocorticoid receptor (GR), 5-hydroxytryptamine (5-HT), kynurenine (KYN) were measured and used for susceptive mechanism research. Results: Body weight, SPT, horizontal movement score and vertical movement score of C57BL/6 mice were found to susceptive to CUMS. SPT, horizontal movement score and vertical movement score of BABL/c showed similar tendency. Hippocampal levels of GR and KYN of normal C57BL/6 mice were significantly lower or higher than that of normal KM, ICR and BABL/c mice. Conclusions: Our study has led to the view that C57BL/6 mice are susceptive to CUMS and hippocampal levels of GR and KYN may be the main mechanism responsible for its susceptibility.目的  筛选对慢性轻度不可预见性应激（CUMS）敏感的小鼠品系，并初步研究其敏感机制，为小鼠抑郁模型的品系筛选、培育及改良提供科学依据。方法  选用KM、ICR、BABL/c、C57BL/6小鼠建立CUMS抑郁模型，通过体重、糖水偏好、旷场实验得分考察不同品系小鼠对慢性轻度不可预见性应激的敏感性。通过对小鼠海马组织糖皮质激素受体、5-羟色胺、犬尿氨酸含量的测定，对其易感机制进行初步研究。结果  造模后C57BL/6小鼠体重、糖水偏好、旷场实验水平运动和垂直运动得分等指标均对CUMS表现出显著敏感性，BABL/c小鼠对糖水偏好、旷场实验水平运动和垂直运动得分较为敏感。对照组C57BL/6小鼠海马组织糖皮质激素受体、犬尿氨酸含量与其他三种小鼠存在显著差异。结论  本研究结果认为C57BL/6 小鼠对CUMS最为敏感，适于建立CUMS抑郁症动物模型，其敏感机制可能与海马组织糖皮质激素受体、犬尿氨酸含量有关

Promoting cold-start items in recommender systems

As one of major challenges, cold-start problem plagues nearly all recommender systems. In particular, new items will be overlooked, impeding the development of new products online. Given limited resources, how to utilize the knowledge of recommender systems and design efficient marketing strategy for new items is extremely important. In this paper, we convert this ticklish issue into a clear mathematical problem based on a bipartite network representation. Under the most widely used algorithm in real e-commerce recommender systems, so-called the item-based collaborative filtering, we show that to simply push new items to active users is not a good strategy. To our surprise, experiments on real recommender systems indicate that to connect new items with some less active users will statistically yield better performance, namely these new items will have more chance to appear in other users' recommendation lists. Further analysis suggests that the disassortative nature of recommender systems contributes to such observation. In a word, getting in-depth understanding on recommender systems could pave the way for the owners to popularize their cold-start products with low costs.Comment: 6 pages, 6 figure

Possible chiral spin liquid state in the S=1/2S=1/2 kagome Heisenberg model

The nature of the ground state for the $S = 1/2$ kagome Heisenberg antiferromagnet (KHAF) has been elusive. We revisit this challenging problem and provide numerical evidence that its ground state might be a chiral spin liquid. Combining the density matrix renormalization group method and analytical analyses, we demonstrate that the previously observed chiral spin liquid phase in the KHAF with longer-range couplings is stable in a broader region. We characterize the nature of the ground state by computing energy derivatives, revealing ground-state degeneracy arising from spontaneous breaking of time-reversal symmetry, and targeting the semion sector. We further investigate the phase diagram in the vicinity of the KHAF and observe a $\sqrt{3}\times\sqrt{3}$ magnetically ordered phase and two valence-bond crystal phases

Energy Efficiency Optimization Design of a Forward-Swept Axial Flow Fan for Heat Pump

As one of the key components of the heat pump system, compared to that of a conventional axial fan, the blade tip area of a forward-swept axial fan is much larger than its blade root, which is the main noise source of the fan and also has an important influence on the fan efficiency. Enhancement of the aerodynamic performance and efficiency of a forward-swept axial fan was addressed by utilizing the Bezier function to parameterize the forward-swept curve on blade tops. In order to quickly select an agent model suitable for the project, an ES model was established by integration of the radial basis function model and the Kriging model. When NSGA-II was combined, multi-objective optimization was carried out with the flow rate and total pressure efficiency as optimization goals. Analysis of optimization results revealed that the optimized axial flow fan’s flow rate and total pressure efficiency were improved to some degree. At the design working point, the fan’s flow rate increased by 1.78 m³/min, while the total pressure efficiency increased by 3.0%. These results lay solid foundation for energy saving of the heat pump system