Effects of Connections Detailing and Friction Dissipation Devices on the Seismic Response of a Hospital Steel Braced Frame Building

Hospitals are post-disaster buildings designed to withstand seismic forces that are amplified with an importance factor of IE= 1.5. Their seismic force-resisting system (SFRS) should be designed with Rd> 2.0, while the interstorey drift at each floor is limited to 1.0%hs. Herein, Rd is the ductility-related force modification factor and hs is the storey height. Although the non-structural components and the hospital contents are not part of this research, they constitute a larger loss in the event of an earthquake. As such, both interstorey drifts and floor accelerations should be within the required limits. Concentrically braced frames (CBFs) are frequently employed as earthquake-resistant systems due to their high stiffness and moderate ductility. However, this system has shown several drawbacks such as the concentration of damage within a floor and high floor accelerations, which may be critical for acceleration-sensitive non-structural components. Recent experimental studies revealed that even moderately ductile concentrically braced frames (MD-CBF) may undergo unintended failure modes due to the limited deformation capacity of brace-to-frame connections. To overcome this drawback, it is proposed to provide an 8tg elliptical clearance band in the brace-to-frame gusset plate instead of a linear 2tg clearance, which is recommended by the code. Herein, tg is the thickness of the gusset plate. The results pointed out that gusset plates with 8tg elliptical clearance require less thickness than that with 2tg linear clearance and provide larger rotation capacity. In consequence, the ductility of MD-CBF with brace-to-frame gusset plates detailed with 8tg elliptical clearance is improved. Furthermore, in order to mitigate the floor acceleration, braces of CBFs can be replaced with sliding friction braces (SF), where each SF brace is made of a friction damper installed in-line with an HSS brace. The proposed sliding friction braced frame (SF-BF) system behaves elastically as a traditional CBF before friction devices are activated and experience nonlinear response after that. Thus, in the case of SF-BF system, the input energy is dissipated by friction devices and all adjacent members such as braces, connections, beams, and columns of the CBF system are designed to remain in the elastic range. It is noted that SF-BF systems are prone to residual interstorey drift, which can be mitigated by: (i) using braced frame’s columns continuous over all floors or (ii) adding back-up moment-resisting frames designed to provide the elastic frame action. The main objective of this thesis was three folds: (i) to investigate the inelastic behaviour of MD-CBF systems with 8tg elliptical clearance gusset plate versus 2tg linear clearance band; (ii) to develop an accurate numerical model for braces equipped with friction dampers using the OpenSees software and (iii) to examine the seismic response of SF-BF systems. To carry out this research, a detailed model of a 4-storey hospital located in Victoria, BC on Site Class C was developed in OpenSees and subjected to 10 historical ground motions for nonlinear time-history analysis. In this manner, a model replicating the MD-CBF with 2tg linear clearance band gusset plates for brace-to-frame connections and a model replicating the MD-CBF with 8tg elliptical clearance band for brace-to-frame gusset plate detail were developed and the nonlinear time-history responses expressed in terms of interstorey drift, residual interstorey drift and floor acceleration were compared. A force-based design method was applied to design the SF-BF system. By optimizing the slip length and slip force in the damper, the slip-lock phase exhibited due to the bearing of the pretensioned bolts can be postponed while maintaining the drift below the code limits. Dynamic instability may become an issue when dampers with large slip lengths are installed. From this research it was found that small difference was observed in the response of MD-CBFs when brace-to-frame gusset plates with 8tg elliptical clearance was selected instead of 2tg linear band detail. When the SF-BF system was designed using the force based design method, the HSS brace was proportioned such that the compression resistance of brace to be equal or greater than 130% slip force. Then, capacity design was employed to design the beams and columns of braced frames. An OpenSees model was developed to simulate the behaviour of Pall friction damper and brace assembly. From nonlinear dynamic analysis, it was found that large residual interstorey drift was observed when columns of braced frame were continuous over two storeys, although the interstorey drift is within the code limit, which is 1.0%hs for a hospital building. To mitigate the residual drift, continuous columns over the building height were considered. However, it was concluded that SF-BFs are not recommended for hospitals located in high risk seismic zones unless back-up moment-resisting frames designed for 25% base shear are provided

Expression of tryptophan 2,3-dioxygenase in mature granule cells of the adult mouse dentate gyrus

New granule cells are continuously generated in the dentate gyrus of the adult hippocampus. During granule cell maturation, the mechanisms that differentiate new cells not only describe the degree of cell differentiation, but also crucially regulate the progression of cell differentiation. Here, we describe a gene, tryptophan 2,3-dioxygenase (TDO), whose expression distinguishes stem cells from more differentiated cells among the granule cells of the adult mouse dentate gyrus. The use of markers for proliferation, neural progenitors, and immature and mature granule cells indicated that TDO was expressed in mature cells and in some immature cells. In mice heterozygous for the alpha-isoform of calcium/calmodulin-dependent protein kinase II, in which dentate gyrus granule cells fail to mature normally, TDO immunoreactivity was substantially downregulated in the dentate gyrus granule cells. Moreover, a 5-bromo-2'-deoxyuridine labeling experiment revealed that new neurons began to express TDO between 2 and 4 wk after the neurons were generated, when the axons and dendrites of the granule cells developed and synaptogenesis occurred. These findings indicate that TDO might be required at a late-stage of granule cell development, such as during axonal and dendritic growth, synaptogenesis and its maturation

Applicability of Preoperative Nuclear Morphometry to Evaluating Risk for Cervical Lymph Node Metastasis in Oral Squamous Cell Carcinoma

Background: We previously reported the utility of preoperative nuclear morphometry for evaluating risk for cervical lymph node metastases in tongue squamous cell carcinoma. The risk for lymph node metastasis in oral squamous cell carcinoma, however, is known to differ depending on the anatomical site of the primary tumor, such as the tongue, gingiva, mouth floor, and buccal mucosa. In this study, we evaluated the applicability of this morphometric technique to evaluating the risk for cervical lymph node metastasis in oral squamous cell carcinoma. Methods: A digital image system was used to measure the mean nuclear area, mean nuclear perimeter, nuclear circular rate, ratio of nuclear length to width (aspect ratio), and nuclear area coefficient of variation (NACV). Relationships between these parameters and nodal status were evaluated by t-test and logistic regression analysis. Results: Eighty-eight cases of squamous cell carcinoma (52 of the tongue, 25 of the gingiva, 4 of the buccal mucosa, and 7 of the mouth floor) were included: 46 with positive node classification and 42 with negative node classification. Nuclear area and perimeter were significantly larger in node-positive cases than in nodenegative cases; however, there were no significant differences in circular rate, aspect ratio, or NACV. We derived two risk models based on the results of multivariate analysis: Model 1, which identified age and mean nuclear area and Model 2, which identified age and mean nuclear perimeter. It should be noted that primary tumor site was not associated the pN-positive status. There were no significant differences in pathological nodal status by aspect ratio, NACV, or primary tumor site. Conclusion: Our method of preoperative nuclear morphometry may contribute valuable information to evaluations of the risk for lymph node metastasis in oral squamous cell carcinoma

ATP spreads inflammation to other limbs through crosstalk between sensory neurons and interneurons

Neural circuits between lesions are one mechanism through which local inflammation spreads to remote positions. Here, we show the inflammatory signal on one side of the joint is spread to the other side via sensory neuron–interneuron crosstalk, with ATP at the core. Surgical ablation or pharmacological inhibition of this neural pathway prevented inflammation development on the other side. Mechanistic analysis showed that ATP serves as both a neurotransmitter and an inflammation enhancer, thus acting as an intermediary between the local inflammation and neural pathway that induces inflammation on the other side. These results suggest blockade of this neural pathway, which is named the remote inflammation gateway reflex, may have therapeutic value for inflammatory diseases, particularly those, such as rheumatoid arthritis, in which inflammation spreads to remote positions

Morphometry of pathologic nodal status, pN(+) and pN(−), in all cases of OSCC.

<p>Morphometry of pathologic nodal status, pN(+) and pN(−), in all cases of OSCC.</p

Illustration of each level of the cervical lymph node.

<p>Illustration of each level of the cervical lymph node.</p