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关键词： axon   dendrite   development   genetics   neural   neuron   vision  

摘要： The neural retina is organized along central-peripheral, dorsal-ventral, and laminar planes. Cellular density and distributions vary along the central-peripheral and dorsal-ventral axis in species including primates, mice, fish, and birds. Differential distribution of cell types within the retina is associated with sensitivity to different types of damage that underpin major retinal diseases, including macular degeneration and glaucoma. Normal variation in retinal distribution remains unreported for multiple cell types in widely used research models, including mouse. Here we map the distribution of all known OFF bipolar cell (BC) populations and horizontal cells. We report significant variation in the distribution of OFF BC populations and horizontal cells along the dorsal-ventral and central-peripheral axes of the retina. Distribution patterns are much more pronounced for some populations of OFF BC cells than others and may correspond to the cell type's specialized functions.

关键词： Dynamic analysis   eccentric operation radial restoring force   superconducting maglev bearing (SMB)  

摘要： Due to the low radial restoring force stiffness of the radial high-T-c superconducting maglev bearing (SMB) in high-T-c superconducting flywheel energy storage system (SFESS), it is difficult to provide enough radial constraint when the rotation speed is high. The dynamic simulation analysis of the SFESS rotor was carried out based on the testing and analysis of the static force results of the SMB. On the one hand, according to the results of dynamic analysis, the flywheel rotor would be eccentric when it is subjected to an unbalanced force. On the other hand, because of the special operation mechanism of the SFESS, the flywheel rotor would be prone to be eccentric before rotation. These two types of eccentricity will affect the operating performance of SFESS. Therefore, the research on the working condition of SFESS under eccentric state not only can predict the operating performance of SFESS in extreme cases in advance but also judge whether the SFESS has eccentric operation by comparing the real-time speed value with the preset value, which is of great significance to the further research of the SFESS.

关键词： Atlanto-axial   Rotary subluxation   Dynamic imaging   Alar ligament   Syncope   C1-C2 fusion  

摘要： Atlanto-axial instability (AAI) is common in the connective tissue disorders, such as rheumatoid arthritis, and increasingly recognized in the heritable disorders of Stickler, Loeys-Dietz, Marfan, Morquio, and Ehlers-Danlos (EDS) syndromes, where it typically presents as a rotary subluxation due to incompetence of the alar ligament. This retrospective, IRB-approved study examines 20 subjects with Fielding type 1 rotary subluxation, characterized by anterior subluxation of the facet on one side, with anormal atlanto-dental interval. Subjects diagnosed with a heritable connective tissue disorder, and AAI had failed non-operative treatment and presented with severe headache, neck pain, and characteristic neurological findings. Subjects underwent a modified Goel-Harms posterior C1-C2 screw fixation and fusion without complication. At 15 months, two subjects underwent reoperation following a fall (one) and occipito-atlantal instability (one). Patients reported improvement in the frequency or severity of neck pain (P < 0.001), numbness in the hands and lower extremities (P = 0.001), headaches, pre-syncope, and lightheadedness (allP < 0.01), vertigo and arm weakness (bothP = 0.01), and syncope, nausea, joint pain, and exercise tolerance (allP < 0.05). The diagnosis of Fielding type 1 AAI requires directed investigation with dynamic imaging. Alignment and stabilization is associated with improvement of pain, syncopal and near-syncopal episodes, sensorimotor function, and exercise tolerance.

关键词： magnetorheological fluid   clutch   permanent magnet   smart fluid   smart actuators  

摘要： In this article, the study of several factors affecting the torque transmission capability of a permanent magnet-based, drum-type magnetorheological fluid (MRF) clutch is presented. These factors are: number of magnetic poles in the magnet assembly, material of the clutch, MRF layer thickness, and relative rotational velocity between the input and output stages of the clutch. For this purpose, a special single-MRF layer clutch was designed and fabricated, one which allows the convenient assembly and disassembly to reduce preparation time for testing. The average transmitted torque of this clutch under several combinations of the aforementioned factors was recorded and analyzed. Additionally, several magnetostatic simulations of the clutch were carried out, and both the magnetic flux density and transmittable torque calculated from the results of these simulation were compared against experimental measurements. It was found that magnet assemblies with lower number of magnetic poles resulted in higher torque outputs, however, the effectiveness of the utilized torque variation mechanism was reduced due to magnetic saturation of the components of the clutch. The material of the clutch was found to have a significant effect at low relative rotational velocities, resulting in a nonlinear relationship between transmitted torque and relative angular velocity. This nonlinear effect was more significant when aluminum was used in the components which interact directly with the MR fluid whereas the use of ferromagnetic components reduced this effect. Finally, the thickness of the MRF layer was found to have a significant effect on the transmitted torque of the MRF clutch, although not according to what magnetostatic simulations predict.

关键词： Porcine circovirus type 2   Cellular inflammatory responses   miR-21   circPDCD4   PDCD4   Porcine kidney 15 cell  

摘要： Porcine circovirus type 2 (PCV2) causes postweaning multisystemic wasting syndrome (PMWS) as well as other PCV-associated diseases (PCVADs), which seriously affect the development of the swine industry. The association between aberrant expression of microRNA-21 (miR-21) and the pathogenesis of inflammatory diseases is already known. Also, our previous study showed elevated ssc-miR-21-5p (miR-21) levels in PCV2-infected porcine kidney 15 (PK-15) cells. However, the functional expression of miR-21 in PCV2 infection is unknown. Here, we found that the miR-21 levels were substantially upregulated in PCV2-infected cells, while the expression of PDCD4 and a PDCD4-derived circRNA (circPDCD4) were downregulated compared with the noninfected cells. The results of RNA immunoprecipitation and dual-luciferase reporter (DLR) assay revealed that circPDCD4 acted as a miR-21 sponge and PDCD4 was a miR-21 target. Functionally, we found that miR-21 overexpression induced the NF-?B pathway along with inflammation in cells exposed to PCV2. Further, the overexpression of PDCD4 or circPDCD4 downregulated miR-21 levels and subsequently, attenuated the miR-21-induced activation of inflammation and the NF-?B pathway. Thus, PCV2 activated the NF-?B pathway and cellular inflammatory responses through regulating circPDCD4, miR-21, and PDCD4 in PK-15 cells.

关键词： invariant clutch size   Lepidodactylus lugubris   life-history trade-offs   reproductive allocation   phylogenetic constraint  

摘要： Although the majority of reptiles show variable clutch sizes, geckos have a fixed clutch size (one or two eggs) and modify reproductive output by changing the offspring size or clutch frequency. However, the clutch size of several geckos is not strictly fixed at the species level;they actually lay both single- and double-egg clutches. We still do not fully understand if clutch size variation within a gecko species is due to adaptive control or reproductive failure like accidental absorption of one of two eggs. This study investigated differences between singleand double-egg clutches of a gecko species in terms of reproductive frequency, egg size, and offspring trait. I housed mourning geckos Lepidodactylus lugubris in a controlled environment and observed their reproduction for seven years. No large differences between single- and double-egg clutches were detected in reproductive frequency and egg size, indicating that life-history trade-offs do not explain much about clutch size variation. Single-egg was comparable in egg size to double-egg, but hatchlings from single-egg showed significantly lower body condition than did those from double-egg. These results suggest that the single-egg is not only a reduction of reproductive output per clutch, but it may provide negative effect on ontogeny.

关键词： Cu-based friction material   torque friction   thermal buckling   hot spots   thermoelastic instability  

摘要： An enhanced Cu-based friction material was prepared by the powder metallurgy techniques and proposed for use in the dry clutch system. The friction characteristics and wear rate of this friction material sliding against 65Mn steel are obtained using Universal Material Tester-5. The friction pairs were subjected to two operating variables, which are sliding speed and temperature. The effect of these variables during the engagement process of the friction pairs is investigated. Knowing the normal applied force and dimension of the clutch disc, the dynamic friction coefficient was translated to friction torque capacity with time. It was found that instability can be excited at low operational conditions when the resulting friction coefficient is high. At 25 celcius, the dynamic friction torque oscillates with time likewise at 400 celcius. Generally, a more stable friction torque is obtained when the sliding speed is varied compared to varying the temperatures. Moreover, the influence of the operating temperatures and sliding speeds on thermal buckling and thermoelastic instability of the friction disc is the second consideration in this work. The onset of thermoelastic instability occurs when the sliding speed exceeded 200 r/min and the results for the growth rate of hot spots were found to agree well with the critical speed of the system. Also, thermal buckling was highly dependent on the temperature difference between the inner and outer radius of the friction disc.

关键词： androgenesis   antioxidant enzymes   egg quality   ionizing radiation   reactive oxygen species   Oncorhynchus mykiss  

摘要： Ionizing radiation (IR) is applied to inactivate the nuclear genome in rainbow trout eggs during induced androgenetic development. However, IR- generated reactive oxygen species (ROS) may affect developmental potential of eggs and reduce the effectiveness of androgenesis. To verify this assumption, androgenetic development of rainbow trout was induced in eggs irradiated with 350 Gy of X-rays. Survival rates, pH of the ovarian fluid and activity of antioxidant enzymes, including SOD, CAT and GPx, were examined in non-irradiated and irradiated eggs originating from four females. Survival rates of androgenetic embryos developing in eggs produced by different females varied from 1% to 57% and these inter-clutch differences were significant. Eggs from female F4, which showed the highest developmental competence for androgenesis, also showed increased activities of SOD, CAT and GPx enzymes. The pH value of the ovarian fluid of each female was over 8 before and after irradiation, therefore it seems that radiation did not affect the ovarian fluid pH. Considering the above-mentioned inter-clutch differences, a strong maternal effect on the effectiveness of androgenesis can be assumed. Eggs with increased activity of antioxidant enzymes before irradiation should be expected to show increased developmental competence for androgenesis.

关键词： Friction  

摘要： To determine the factors affecting the dynamic transmitted torque response characteristics of the wet clutch, the oil film pressure, the asperity contact pressure, the applied pressure, and the dynamic transmitted torque model were established, using the fourth-order Runge-Kutta numerical method to couple the oil film thickness and the speed difference to obtain the change curve of the joint pressure and the transmitted torque. The established model was used to study the influence of the pressure hysteresis time, lubricant viscosity, friction lining permeability, friction pair equivalent elastic modulus, and surface combined roughness RMS on the dynamic transmitted torque response during the wet clutch engagement. The results indicate that the longer the pressure hysteresis time, the smaller the permeability of the friction lining, the smaller the equivalent elastic modulus, the greater surface combined roughness RMS, the more delayed the response of the transmitted torque, and the smaller the level of jerk of the wet clutch engagement. Also, the lower the lubricant viscosity, the greater the permeability of the friction lining, and the smaller the equivalent elastic modulus is and the greater surface combined roughness RMS is, the more sensitive the transmitted torque response is to pressure response changes.

关键词： 湿式离合器   流体仿真   热流耦合   温度场  

摘要： 为改善滑摩工况下湿式离合器油路冷却效果,考虑气液两相混合效应的影响,对离合器接合过程中油路的散热特性进行数值模拟。基于κ-ε两层湍流模型和欧拉方法中VOF(volume of fluent model)模型,采用STAR-CCM+软件建立含径向槽的离合器内油路模型,进行稳态计算,研究了入口流量及相对转速对摩擦副流域温度场的影响规律。改变出油孔的布置形式,研究其对摩擦副片间流体油液占比的影响。结果表明:入口流量的增加主要改善滑摩面的热传递情况;转速差的提高不利于摩擦片壁面热传递;出油孔采用中间分布的形式更利于摩擦片外径处的油液占比。另外,通过正交法建立多因素正交仿真方案计算得到各因素影响程度的主次关系,以及给定条件下各个因素的最佳水平搭配。