A computer-aided system for space welding

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 1994.Includes bibliographical references (leaves 118-133).by Takatoshi Nakamura.M.S

Fatigue crack initiation in weldments

Thesis (Ocean. E.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, 1994, and Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1994.Includes bibliographical references (leaves 160-162).by Takatoshi Nakamura.M.S.Ocean.E

Technological rules and constraints affecting design of precast concrete housing

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Architecture, 1994.Includes bibliographical references (leaves 115-117).Precast concrete technology is of great importance in multifamily housing. This technology provides the possibility to the industrialize housing construction and thus enhance the availability and quality of houses. With regard to the design process of precast concrete housing, architectural and technological concepts have to be woven into housing systems by iterative processes. Although precast concrete technology is an offshoot of reinforced concrete technology, its structural nature and construction process is not the same: its identification with the concept of industrialization makes this technology quite different from cast-in-place concrete. In other words, the processes of precasting, of transportation and handling, and of the erection of precast concrete building systems give significant advantages to housing systems, but they pose technological constraints to as well. This thesis investigates the technological rules and constraints of precast concrete structural systems which provide technological approaches to precast concrete housing systems. First, the methodology of the considerations of structural systems is introduced. Second, the technological rules and constraints of precasting, transportation, and construction methods are discussed in detail. Then, the technological rules and constraints of three typical structural systems, including unbraced frame, braced frame, and large panel, are examined.by Takatoshi Nakamura.M.S

The Sliding Mode Control of Bridge Vibration under a Moving Vehicle

The linear quadratic regulator theory is applied to the active control of bridge vibration conduced by traffic loads. As the bride-vehicle system is the time varying system, the stationary LQR control is not optimal control for the bridge vibration. In bridge vibration under traffic loads, uncertain factors such as the vehicle number, the types of vehicle moving speed etc. exist, therefore, the control theory has to be considered these factors. Then, for these uncertainties, the robust control is expected. This study concerned with the control of bridge vibration under a moving vehicle using by the sliding mode theory that has robustness for the time-varying system. The effectiveness of sliding mode control theory is discussed by the numerical simulations for active and hybrid control of bridge vibration

Cellular Injury of Cardiomyocytes during Hepatocyte Growth Factor Gene Transfection with Ultrasound-Triggered Bubble Liposome Destruction

We transfected naked HGF plasmid DNA into cultured cardiomyocytes using a sonoporation method consisting of ultrasound-triggered bubble liposome destruction. We examined the effects on transfection efficiency of three concentrations of bubble liposome (1 × 106, 1 × 107, 1 × 108/mL), three concentrations of HGF DNA (60, 120, 180 μg/mL), two insonification times (30, 60 sec), and three incubation times (15, 60, 120 min). We found that low concentrations of bubble liposome and low concentrations of DNA provided the largest amount of the HGF protein expression by the sonoporated cardiomyocytes. Variation of insonification and incubation times did not affect the amount of product. Following insonification, cardiomyocytes showed cellular injury, as determined by a dye exclusion test. The extent of injury was most severe with the highest concentration of bubble liposome. In conclusion, there are some trade-offs between gene transfection efficiency and cellular injury using ultrasound-triggered bubble liposome destruction as a method for gene transfection

Impact of laparoscopic surgery on short‐term and long‐term outcomes in elderly obese patients with colon cancer

[Background] Laparoscopic surgery is reported to be useful in obese or elderly patients with colon cancer, who are at increased risk of postoperative complications because of comorbidities and physical decline. However, its usefulness is less clear in patients who are both elderly and obese and may be at high risk of complications. [Methods] Data for obese patients (body mass index ≥25) who underwent laparoscopic or open surgery for stage II or III colon cancer between January 2009 and December 2013 were collected by the Japan Society of Laparoscopic Colorectal Surgery. Surgical outcomes, postoperative complications, and relapse-free survival (RFS) were compared between patients who underwent open surgery and those who underwent laparoscopic surgery according to whether they were elderly (≥70 y) or nonelderly (<70 y). [Results] Data of 1549 patients (elderly, n = 598; nonelderly, n = 951) satisfied the selection criteria for analysis. Length of stay was shorter and surgical wound infection was less common in elderly obese patients who underwent laparoscopic surgery than in those underwent open surgery. There were no significant between-group differences in overall complications, anastomotic leakage, ileus/small bowel obstruction, or RFS. There were also no significant differences in RFS after laparoscopic surgery according to patient age. [Conclusion] Laparoscopic surgery is safe in elderly obese patients with colon cancer and does not worsen their prognosis. There was no significant difference in the effectiveness of laparoscopic surgery between obese patients who were elderly and those who were nonelderly