For intracellular separation between metabolic and physiological entities eukaryotic cells develo... more For intracellular separation between metabolic and physiological entities eukaryotic cells developed a complex compartmentalization by intracellular membranes. To allow directed transport of cargo and membranes to their destination organelle, they use a dynamic but highly specific vesicular transport system. The recognition of vesicles at their target compartment is initiated by the reversible interaction of so-called tethering complexes and Rab-GTPases (e.g. Ypt7) prior to SNARE-mediated membrane fusion. Although structural data on coiled-coil and Rab-independent tethers exist, molecular insight into the structure of a Rab-binding multisubunit tethering complexes (MTCs), like the endosomal CORVET and the vacuolar HOPS complex, has been lacking to date. Here we analyzed the HOPS complex structure using transmission electron microscopy (TEM) combined with single particle analysis. We show that the heterohexameric HOPS is highly flexible forming a seahorse-like structure. Surprisingly, the two Rab-binding proteins Vps39 and Vps41 are at opposite ends, implicating that HOPS bridges Ypt7-positive membranes. We also specified the parts of the SNARE complex that bind to the Vps33 subunit, which is proximal to the Rabbinding site Vps41. This suggests that HOPS coordinates Rab-mediated tethering with SNARE-driven fusion. Taken together our data demonstrate that the conserved vacuolar/lysosomal HOPS tethering complex combines different activities; the vesicle recognition by Rab-binding, bridging of vesicular and target membrane and the activation of SNARE mediated fusion.
Air traffic controller fatigue has recently received considerable attention from researchers beca... more Air traffic controller fatigue has recently received considerable attention from researchers because it is one of the main causes of air traffic incidents. Numerous research studies have been conducted to extract speech features related to fatigue, and their practical utilization has achieved some positive detection results. However, there are still challenges associated with the applied speech features usually being of high dimension, which leads to computational complexity and inefficient fatigue detection. This situation makes it meaningful to reduce the dimensionality and select only a few efficient features. This paper addresses these problems by proposing a high-efficiency fatigued speech selection method based on improved compressed sensing. For adapting a method to the specific field of fatigued speech, we propose an improved compressed sensing construction algorithm to decrease the reconstruction error and achieve superior sparse coding. The proposed feature selection metho...
As air traffic volume increases, the air traffic controller (ATC) fatigue has become a major caus... more As air traffic volume increases, the air traffic controller (ATC) fatigue has become a major cause for air traffic accidents. However, the conventional fatigue-detecting methods based on speech are neither effective nor accurate because the speech signals are nonlinear and complicated. In this paper, an ATC fatigue-detecting method based on fractal dimension (FD) is proposed. Firstly, a special speech database of ATC radiotelephony communications is constructed. These radiotelephony communications are obtained from Air Traffic Management Shandong Bureau of China. Then, speech signals implement a wavelet decomposition and FD calculation. The calculation result shows the significant difference among the FD of the speech signal before and after fatigue. Furthermore, a novel fatigue feature of the ATC based on the FD of speech is built. A series of experiments are conducted to detect the ATC fatigue with the fatigue feature comparison process and a support vector machine (SVM). The resu...
For intracellular separation between metabolic and physiological entities eukaryotic cells develo... more For intracellular separation between metabolic and physiological entities eukaryotic cells developed a complex compartmentalization by intracellular membranes. To allow directed transport of cargo and membranes to their destination organelle, they use a dynamic but highly specific vesicular transport system. The recognition of vesicles at their target compartment is initiated by the reversible interaction of so-called tethering complexes and Rab-GTPases (e.g. Ypt7) prior to SNARE-mediated membrane fusion. Although structural data on coiled-coil and Rab-independent tethers exist, molecular insight into the structure of a Rab-binding multisubunit tethering complexes (MTCs), like the endosomal CORVET and the vacuolar HOPS complex, has been lacking to date. Here we analyzed the HOPS complex structure using transmission electron microscopy (TEM) combined with single particle analysis. We show that the heterohexameric HOPS is highly flexible forming a seahorse-like structure. Surprisingly, the two Rab-binding proteins Vps39 and Vps41 are at opposite ends, implicating that HOPS bridges Ypt7-positive membranes. We also specified the parts of the SNARE complex that bind to the Vps33 subunit, which is proximal to the Rabbinding site Vps41. This suggests that HOPS coordinates Rab-mediated tethering with SNARE-driven fusion. Taken together our data demonstrate that the conserved vacuolar/lysosomal HOPS tethering complex combines different activities; the vesicle recognition by Rab-binding, bridging of vesicular and target membrane and the activation of SNARE mediated fusion.
Air traffic controller fatigue has recently received considerable attention from researchers beca... more Air traffic controller fatigue has recently received considerable attention from researchers because it is one of the main causes of air traffic incidents. Numerous research studies have been conducted to extract speech features related to fatigue, and their practical utilization has achieved some positive detection results. However, there are still challenges associated with the applied speech features usually being of high dimension, which leads to computational complexity and inefficient fatigue detection. This situation makes it meaningful to reduce the dimensionality and select only a few efficient features. This paper addresses these problems by proposing a high-efficiency fatigued speech selection method based on improved compressed sensing. For adapting a method to the specific field of fatigued speech, we propose an improved compressed sensing construction algorithm to decrease the reconstruction error and achieve superior sparse coding. The proposed feature selection metho...
As air traffic volume increases, the air traffic controller (ATC) fatigue has become a major caus... more As air traffic volume increases, the air traffic controller (ATC) fatigue has become a major cause for air traffic accidents. However, the conventional fatigue-detecting methods based on speech are neither effective nor accurate because the speech signals are nonlinear and complicated. In this paper, an ATC fatigue-detecting method based on fractal dimension (FD) is proposed. Firstly, a special speech database of ATC radiotelephony communications is constructed. These radiotelephony communications are obtained from Air Traffic Management Shandong Bureau of China. Then, speech signals implement a wavelet decomposition and FD calculation. The calculation result shows the significant difference among the FD of the speech signal before and after fatigue. Furthermore, a novel fatigue feature of the ATC based on the FD of speech is built. A series of experiments are conducted to detect the ATC fatigue with the fatigue feature comparison process and a support vector machine (SVM). The resu...
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Papers by Zhiyuan Shen