The diterpenoid phytohormone gibberellin (GA) controls diverse developmental processes throughout the plant life cycle. DELLA proteins are master growth repressors that function immediately downstream of the GA receptor to inhibit GA signaling. By doing so, DELLAs also play pivotal roles as integrators of internal developmental signals from multiple hormone pathways and external cues. DELLAs are likely nuclear transcriptional regulators, which interact with other transcription factors to modulate expression of GA-responsive genes. DELLAs are also involved in maintaining GA homeostasis through feedback up-regulating expression of GA biosynthesis and receptor genes. However, the molecular mechanisms by which DELLAs restrict growth and development are largely unknown. This study reveals an important step of the mechanism. Previous microarray studies identified SCARECROW-LIKE 3 (SCL3) as a direct target gene of DELLA in Arabidopsis seedlings. SCL3 expression is induced by DELLA and repressed by GA. Unexpectedly, a scl3 null mutant displays reduced GA responses and elevated expression of GA biosynthesis genes during seed germination and seedling growth, indicating that SCL3 functions as a positive regulator of GA signaling. SCL3 seems to act as an attenuator of DELLA proteins. Transient expression, ChIP, and co-IP studies show that SCL3 autoregulates its own transcription by directly interacting with DELLA. Our data further show that SCL3 and DELLA antagonize each other in controlling both downstream GA responses and upstream GA biosynthetic genes. This work is beginning to shed light on how this complex regulatory network achieves GA homeostasis and controls GA-mediated growth and development in the plant.gibberellin-regulated development | hormone homeostasis | SCARECROW-LIKE 3-DELLA interaction | DELLA attenuator B ioactive gibberellins (GAs) are a class of phytohormones that plays critical roles in modulating plant growth and development in response to internal developmental programs and environmental cues (1-4). DELLA proteins are likely nuclear transcriptional regulators that function as master growth repressors by inhibiting all aspects of GA responses (1, 5, 6). Binding of GA to its receptor GA INSENSITIVE DWARF1 (GID1) enhances the GID1-DELLA interaction, which, in turn, leads to the rapid proteolysis of DELLA through the ubiquitin-proteasome pathway and allows transcriptional reprogramming of GA-responsive genes (7-11). A specific ubiquitin E3 ligase SCF SLY1/GID2 (Skp1-Cullin-Fbox protein complex) is responsible for recruiting DELLA for polyubiquitination (12)(13)(14)(15). DELLA proteins belong to a subfamily of the plant-specific GRAS family [for GA INSENSITIVE (GAI), REPRESSOR OF gal-3 (RGA), and SCARECROW (SCR)] of regulatory proteins (5, 16). In addition to the C-terminal GRAS domain that is common in all GRAS family members, DELLA protein also contains a unique DELLA domain in its N terminus that is required for GID1 binding and GA-induced degradation (7,(17)(18)(19)(20). Arabidopsis contains five DEL...

The abnormalities of CD and its complications can be identified by multidetector CT with CT-E, dynamic enhancement, CTA, and 3D imaging, and they are important methods in diagnosing CD. Complications of CD can be shown better when CT-E is performed.

In the three-phase four-wire low-voltage micro grid, three-phase imbalance usually happens because of a large number of single-phase loads. In this situation, the traditional control method cannot effectively control the voltage and frequency stability when the low-voltage micro grid operates in the island mode. According to the characteristics of the three-phase four-wire low-voltage micro grid, this paper designs a single-phase independent control based on the droop control. This paper firstly uses the improved droop control considering that the impedance characteristic of the low voltage micro gird is mainly resistance, and also designs single-phase independent control to ensure the control system have the ability to run under the unbalanced loads. Then this paper designs a two-level control strategy to control the voltage and frequency in the micro grid during the island operation. Finally, a simulation analysis based on the proposed method is used to prove the effectiveness. A micro grid is set up on PSCAD, and verifies the effectiveness of the single-phase control strategy based on the improved droop control. The proposed method can also realize the requirement of the voltage and frequency stability during the island operation. At the same time, the control method proposed in this paper can achieve the control objective under the condition of unbalanced three-phase.

The Mechanics between belt and pulley in flat belt drive running is complicated. Since no inertial force or only partial inertial force was taken into account before, it is necessary to add in the inertial affection fully for more accurate dynamic analysis modeling of the flat belt drive. In the assumption that belt material is deformed in linear elasticity and the flat belt drive is running in steady state, the dynamic equilibrium equations of radial and tangent directions are presented and simplified through the belt infinitesimal element processing and the equations associated with mechanical coefficients and dimensions are also derived. After building up the relations of constitutive equations and geometric boundary equations, the solutions to the dynamic differential equations have been found. The sample flat belt drive is introduced for performing method application and obtained adequate calculation results. It is concluded that the presented method calculation results make the maximum transmission momentum tends to be smaller and the slip angle tends to be bigger than the traditional one. And the fluctuation range is mainly depending on the belt speed and the belt stiffness. This method is valuable for dynamic analysis and the design methodology of belt drive.

Twice serious deformation occurred in the Wangxia unstable rock mass in 2010 and 2011 in Wushan country in the Three Gorges Reservoir. It formed a large dangerous factor for the local resident and channel safety. Based on the detailed investigation of the new cracks, deformation history, GPS observations, total station monitoring and crack displacement monitoring data analysis, analyzed comprehensively the deformation and reasons of the unstable rock. The researches show that the deformation type of the unstable rock mass contains gradual change and mutation, should adopt the corresponding monitoring methods and monitoring frequency in different deformation stages based on the geological survey and monitoring the key parts of the unstable rock mass. The destruction of the Wangxia unstable rock was a gradual process, controlled by 5 key cracks, which were crack T11, T12, T13, T16, and T10, consider the Wangxia unstable rock was subsided extrusion type collapse.