IST Austria Thesis

The hippocampus is a key brain region for memory and notably for spatial memory, and is needed for both spatial working and reference memories. Hippocampal place cells selectively discharge in specific locations of the environment to form mnemonic represen tations of space. Several behavioral protocols have been designed to test spatial memory which requires the experimental subject to utilize working memory and reference memory. However, less is known about how these memory traces are presented in the hippo campus, especially considering tasks that require both spatial working and long -term reference memory demand. The aim of my thesis was to elucidate how spatial working memory, reference memory, and the combination of both are represented in the hippocampus. In this thesis, using a radial eight -arm maze, I examined how the combined demand on these memories influenced place cell assemblies while reference memories were partially updated by changing some of the reward- arms. This was contrasted with task varian ts requiring working or reference memories only. Reference memory update led to gradual place field shifts towards the rewards on the switched arms. Cells developed enhanced firing in passes between newly -rewarded arms as compared to those containing an unchanged reward. The working memory task did not show such gradual changes. Place assemblies on occasions replayed trajectories of the maze; at decision points the next arm choice was preferentially replayed in tasks needing reference memory while in the pure working memory task the previously visited arm was replayed. Hence trajectory replay only reflected the decision of the animal in tasks needing reference memory update. At the reward locations, in all three tasks outbound trajectories of the current arm were preferentially replayed, showing the animals’ next path to the center. At reward locations trajectories were replayed preferentially in reverse temporal order. Moreover, in the center reverse replay was seen in the working memory task but in the other tasks forward replay was seen. Hence, the direction of reactivation was determined by the goal locations so that part of the trajectory which was closer to the goal was reactivated later in an HSE while places further away from the goal were reactivated earlier. Altogether my work demonstrated that reference memory update triggers several levels of reorganization of the hippocampal cognitive map which are not seen in simpler working memory demand s. Moreover, hippocampus is likely to be involved in spatial decisions through reactivating planned trajectories when reference memory recall is required for such a decision

Triiodothyronine participates in odontoblast differentiation of apical papilla stem cells through regulation of ERK and p38MAPK signaling pathways

Purpose: To investigate the effect of triiodothyronine (T3) in odontoblast differentiation of apical papilla stem cells, and the mechanism of action involved. Methods: Apical unclosed permanent molars extracted from patients due to orthodontics and impaction were selected. The extracted teeth were cultured in the isolation stage of SCAP cells. The cells were exposed to different concentrations of T3. The effects of ERK and p38 MAPK signaling pathways on activity of alkaline phosphatase (ALP) were determined. Calcium deposition was measured using a calcium determination kit, while the expression of BMP - 2 protein by T3 was determined by Western blot assay. Fluorescence quantitative polymerase chain reaction (FqPCR) method was used to determine the mRNA expression of BMP. Results: The ALP activities were significantly higher in T3 groups than in control group. Relative to control, there were marked differences in ALP activity and calcium deposition in T3 group, T3 + PD group and T3 + SB group (p < 0.05). Relative to control, the mRNA and protein expressions of BMP-2 in T3 group were increased significantly (p < 0.05). Conclusion: Triiodothyronine regulates the differentiation of apical papilla stem cells into dentin through ERK and p38MAPK signaling pathways. This provides the mechanism underlying odontoblast differentiation of apical papilla stem cells

Human action recognition in smart classroom

Abstrac

Endoglin Is Essential for the Maintenance of Self-Renewal and Chemoresistance in Renal Cancer Stem Cells.

Renal cell carcinoma (RCC) is a deadly malignancy due to its tendency to metastasize and resistance to chemotherapy. Stem-like tumor cells often confer these aggressive behaviors. We discovered an endoglin (CD105)-expressing subpopulation in human RCC xenografts and patient samples with a greater capability to form spheres in vitro and tumors in mice at low dilutions than parental cells. Knockdown of CD105 by short hairpin RNA and CRISPR/cas9 reduced stemness markers and sphere-formation ability while accelerating senescence in vitro. Importantly, downregulation of CD105 significantly decreased the tumorigenicity and gemcitabine resistance. This loss of stem-like properties can be rescued by CDA, MYC, or NANOG, and CDA might act as a demethylase maintaining MYC and NANOG. In this study, we showed that Endoglin (CD105) expression not only demarcates a cancer stem cell subpopulation but also confers self-renewal ability and contributes to chemoresistance in RCC

Assembly responses of hippocampal CA1 place cells predict learned behavior in goal-directed spatial tasks on the radial eight-arm maze

Hippocampus is needed for both spatial working and reference memories. Here, using a radial eight-arm maze, we examined how the combined demand on these memories influenced CA1 place cell assemblies while reference memories were partially updated. This was contrasted with control tasks requiring only working memory or the update of reference memory. Reference memory update led to the reward-directed place field shifts at newly rewarded arms and to the gradual strengthening of firing in passes between newly rewarded arms but not between those passes that included a familiar-rewarded arm. At the maze center, transient network synchronization periods preferentially replayed trajectories of the next chosen arm in reference memory tasks but the previously visited arm in the working memory task. Hence, reference memory demand was uniquely associated with a gradual, goal novelty-related reorganization of place cell assemblies and with trajectory replay that reflected the animal’s decision of which arm to visit next

Uplift of the Longmen Shan range and the Wenchuan earthquake

ABSTRACT: The 12 May 2008 Wenchuan earthquake (M-s,=8.0) struck on the Longmen Shan foreland thrust zone. The event took place within the context of long-term uplift of the Longmen Shan range is a result of the extensive eastward-extrusion of crustal materials from the Tibetan plateau against the rheologically strong crust of the Sichuan Basin. The Longmen Shan range is characterized by a Pre-Sinian crystalline complex constrained by the Maoxian-Wenchuan-Kangding ductile detachment at the western margin and the Yingxiu-Beichuan-Luding ductile thrust at the eastern margin. The Longmen Shan uplift was initiated by intracontinental subduction between the Songpan-Ganzi terrane and the Yangtze block during the Pre-Cenozoic. The uplift rate was increased considerably by the collision between the Indian and Eurasian plates since similar to 50 Ma. The Wenchuan earthquake resulted in two major NE-striking coseismic ruptures (i.e., the similar to 275 km long Yingxiu-Beichuan-Qingchuan fault and the similar to 100 km long Anxian-Guanxian fault). Field investigations combined with focal solutions and seismic reflection profiles suggest that the coseismic ruptures are steeply dipping close-to-pure reverse or right reverse oblique slip faults in the similar to 15 km thick tipper crust. These faults are unfavorably oriented for frictional slip in the horizontally compressional regime, so that they need a long recurrence interval to accumulate the tectonic stress and fluid pressure to critically high levels for the formation of strong earthquakes at a given locality. It is also found that all the large earthquakes (M-s>7.0) occurred in the fault zones across which the horizontal movement velocities measured by the GPS are markedly low (<3 mm/yr). The faults, which constitute the northeastern fronts of the enlarging Tibetan plateau against the strong Sichuan Basin, Ala Shan and Ordos blocks, are very destructive, although their average recurrence intervals are generally long

Design and operational parameters optimisation of a citrus substrate filling and transporting machine

Aiming to address the problem of low mechanisation of filling and transporting citrus seedling pots in China, a new type of pot filling and transporting machine with 120 pots at a time was designed. Based on the study of flow characteristics of the seedling substrate, key components of the filling and transporting machines, such as the hopper component, transmission mechanism, flip mechanism, and steering mechanism, were designed. The effects of the opening width of the hopper, the rotating speed of the stirring shaft, the moisture content of the seedling substrate, and the forward speed of the transporting device on the filling effect of the seedling pot were studied by the experimental method, and the optimal operation parameters were determined. The prototype tests were repeated 3 times with the best combination of parameters. The test results indicate that the machine was in good condition for loading and unloading. The number of filling pots was 120 once, and the average filling time was 40 s. The average filling mass was 1.881 kg, 0.006 kg different from the predicted value of 1.887 kg, and the relative error was 0.32%. The coefficient of variation of the mass was 2.97%, which was 0.12% different from the predicted value of 2.85%, and the relative error was 4.0%. This designed machine can provide a reference for developing and optimising the citrus substrate filling and transporting machine

In Situ X-ray Absorption Spectroscopy of Metal/Nitrogen-doped Carbons in Oxygen Electrocatalysis

Metal/nitrogen-doped carbons (M−N−C) are promising candidates as oxygen electrocatalysts due to their low cost, tunable catalytic activity and selectivity, and well-dispersed morphologies. To improve the electrocatalytic performance of such systems, it is critical to gain a detailed understanding of their structure and properties through advanced characterization. In situ X-ray absorption spectroscopy (XAS) serves as a powerful tool to probe both the active sites and structural evolution of catalytic materials under reaction conditions. In this review, we firstly provide an overview of the fundamental concepts of XAS and then comprehensively review the setup and application of in situ XAS, introducing electrochemical XAS cells, experimental methods, as well as primary functions on catalytic applications. The active sites and the structural evolution of M−N−C catalysts caused by the interplay with electric fields, electrolytes and reactants/intermediates during the oxygen evolution reaction and the oxygen reduction reaction are subsequently discussed in detail. Finally, major challenges and future opportunities in this exciting field are highlighted.</p