Development of high-speed imaging techniques for C. elegans nervous system studies

We report high-speed imaging techniques for C. elegans nervous systems studies. We introduce C. elegans, the main model organism in this dissertation, and neuroscientific and biomedical studies using C. elegans involving calcium imaging, nerve regeneration, and drug screening. We review technologies including confocal microscopy and microfluidic devices used in the neuroscientific and biomedical studies We discuss development of a high-speed laser scanning confocal microscope capable of flexible control of imaging conditions, fast imaging speed, and large field-of-view. We provides the design principles used in the development of the confocal microscope including the optical, electrical, and software implementation, and the details of the confocal microscope we built based on the design principles. We present the performance characterization of the confocal microscope, then a few sample images obtained with the confocal microscope. We present development of time-lapse volumetric confocal imaging of whole animal C. elegans Ca²⁺ dynamics. We provide the design of the time-lapse volumetric confocal imaging system including a microfluidic device to accommodate the whole animal within the field-of-view of the imaging system. We examine the feasibility of the volumetric confocal imaging of a whole animal, and demonstrate imaging of the whole animal C. elegans neurons’ response to NaCl within a 630 × 150 × 25 μm³ volume at 2 Hz rate. We report a high-throughput automated imaging platform for C. elegans nerve regeneration study. We describe the design of the automated imaging platform and the automation flow, and characterizes the performance of the platform. The imaging platform can obtain high-resolution 3D confocal images of 20 animals in 10 minutes. We show sample images of C. elegans anterior lateral microtubule nerve regeneration examples acquired via the automated imaging platform. We demonstrate a planar laser activated neuronal scanning platform (PLANS), a high-throughput animal examination system for drug screening. We explain the construction of PLANS involving the optics, the microfluidic device, and the electronics. The PLANS system can scan an animal in less than 5 ms with a spatial sampling resolution of 3 μm FWHM. We show sample scanning results of a Huntington’s disease model of C. elegans. We summarize the studies discussed in this dissertation, and suggest relevant future research to follow up on the studies.Electrical and Computer Engineerin

Online home appliance control using EEG-Based brain-computer interfaces

Brain???computer interfaces (BCIs) allow patients with paralysis to control external devices by mental commands. Recent advances in home automation and the Internet of things may extend the horizon of BCI applications into daily living environments at home. In this study, we developed an online BCI based on scalp electroencephalography (EEG) to control home appliances. The BCI users controlled TV channels, a digital door-lock system, and an electric light system in an unshielded environment. The BCI was designed to harness P300 andN200 components of event-related potentials (ERPs). On average, the BCI users could control TV channels with an accuracy of 83.0% ?? 17.9%, the digital door-lock with 78.7% ?? 16.2% accuracy, and the light with 80.0% ?? 15.6% accuracy, respectively. Our study demonstrates a feasibility to control multiple home appliances using EEG-based BCIs

The usefulness of the Korean version of modified Mini-Mental State Examination (K-mMMSE) for dementia screening in community dwelling elderly people

BACKGROUND: We assessed whether the Korean version of modified Mini-Mental State Examination (K-mMMSE) has improved performance as a screening test for cognitive impairment or dementia in a general population compared with the Korean Mini-Mental State Examination (K-MMSE). METHODS: Screening interviews were conducted with people aged 65 and over in Noam-dong, Namwon-city, Jeonbuk province. There were 522 community participants, of whom 235 underwent clinical and neuropsychological examination for diagnosis of dementia and Cognitive Impairment No Dementia (CIND). Sensitivity, specificity and areas under the receiver operating characteristic (ROC) curves for the K-mMMSE and the K-MMSE were the main outcome measures. RESULTS: Cronbach's alpha for the K-mMMSE was 0.91, compared with 0.84 for the K-MMSE. The areas under the ROC curves in identifying all levels of CIND or dementia were 0.91 for the K-mMMSE and 0.89 for the K-MMSE (P < 0.05). For the K-mMMSE, the optimal cut-off score for a diagnosis of CIND was 69/70, which had a sensitivity of 0.86 and a specificity of 0.79, while, for a diagnosis of dementia, the optimal cut-off score of 59/60 had a sensitivity of 0.91 and a specificity of 0.78. The K-mMMSE also had a high test-retest reliability (r = 0.89). CONCLUSION: Our findings indicate that the K-mMMSE is more reliable and valid than the K-MMSE as a cognitive screen in a population based study of dementia. Considering the test characteristics, the K-MMSE and modified version are expected to be optimally used in clinical and epidemiologic fields

Effects of part-to-part gap and the direction of welding on laser welding quality

Engineering & Systems DesignThe use of laser welding has become quite widespread because it can achieve higher productivity than spot welding. This is due to its desirable features, which include high power density, faster welding speed, highly accurate welding, and excellent repeatability. In addition, laser welding can minimize the distortion in heat-affected zones (HAZs), and there is no tooling that wears out or must be changed over. In spite of these advantages, laser welding still causes many problems when used on compositions such as galvanized steel and aluminum alloy. Galvanized steel, for example, is composed of a zinc layer whose physical parameters differ from those of steel as a base material. Zinc vaporizes at a temperature of 907 K, whereas steel begins to melt at 1510 K. This phenomenon causes serious defects in welds because the pressure of zinc is more powerful than that of steel. As a result, a certain manipulable control is needed in order for the zinc coating to be able to evaporate. To prevent this circumstance, the following solutions have been proposed: (i) a de-gassing method that induces the zinc fumes to escape from the part-to-part gap between two materials; (ii) the removal of zinc layers that will be joined together; (iii) a pulsed laser method that minimizes zinc vaporization using a high energy per pulse and a short pulse duration; (iv) a laser hybrid method; and (v) the addition of additional elements to the surface, which form a compound with the vaporizing zinc. Despite these suggestions, applications involving zinc-coated steels are rarely used in the automotive industry because the shapes of the materials to be welded are not always uniform. In this study, we ascertain the effects of the part-to-part gap and the direction of welding on the quality of laser welding. Using a 2 kW fiber laser and galvanized steel sheets (with thicknesses of 1.4 mm and 1.8 mm), our experiments employed lap welding, which has been applied to side members in the automotive industry. The experimental design was used with a 33 factorial design with 3 replications. The three types of welding direction used are ascendance, descendance, and a uniform gap. Based on the experiments, using analysis of variance (ANOVA) it was determined that the direction of welding is an important factor that can affect the weld quality. In addition, the differences between the shear tensile strengths in the ascendance and descendance directions were determined using a t-Test. The maximum shear tensile strength in the ascendance direction was achieved with a laser power of 2000 W and a welding speed of 2100 mm/min, followed by a part-to-part gap of 0.32 mm/min as the steepest ascent method. Moreover, we analyzed cross-sections of sampling specimens, varying the gap differences in order to verify the differences in shear tensile strength based on two different directions of welding.ope