Theoretical and Experimental Study of the Biefeld Brown Effect

By applying high voltage to an asymmetric capacitor, a thrust is created in the direction from the cathode to anode electrodes of the capacitor. Because of the high voltages, the anode ionizes the dielectric medium (air) and creates an “ion wind” by repelling the positively charged ions toward the cathode. This thrust is a result of the law of conservation of momentum. The application to this thrust has been observed in popular media as a levitating device (craft) but its full applications are still unknown and limited to lightweight crafts. In order to uncover its potential applications, this Honors Thesis built 47 lightweight crafts and tested them with an Ion Power Supply (GR8) that ranged its voltage from 20 kV to 30 kV. From the 47 crafts, the Quadrangle, Q2, which is a 30 x 30 cm2 square shaped craft, was the ideal craft. A variable payload measured to observe the relationship between the current supplied by the Power Supply and the weight of the craft

Temperature measurements of heated microcantilevers using scanning thermoreflectance microscopy

We report the development of scanning thermoreflectance thermometry and its application for steady and dynamic temperature measurement of a heated microcantilever. The local thermoreflectance signal of the heated microcantilever was calibrated to temperature while the cantilever was under steady and periodic heating operation. The temperature resolution of our approach is 0.6 K, and the spatial resolution is 2 μm, which are comparable to micro-Raman thermometry. However, the temporal resolution of our approach is about 10 μsec, which is significantly faster than micro-Raman thermometry. When the heated microcantilever is periodically heated with frequency up to 100 kHz, we can measure both the in-phase and out-of-phase components of the temperature oscillation. For increasing heating frequency, the measured cantilever AC temperature distribution tends to be confined in the vicinity of the heater region and becomes increasingly out of phase with the driving signal. These results compare well with finite element simulations

Erratum to: A genome-wide assessment of genetic diversity and population structure of Korean native cattle breeds

Background: The native cattle breeds are an important genetic resource for meat and milk production throughout Asia. In Asia cattle were domesticated around 10,000 years ago and in Korea cattle are being raised since 2000 B.C. There are three native breeds of cattle in Korea viz. Brown Hanwoo, Brindle Hanwoo and Jeju Black. While one of these breeds, Brown Hanwoo, is a part of a Food and Agricultural Organization and national genetic evaluation plans, others get little attention. This study is an effort to understand and provide a detailed insight into the population structure and genetic variability of the Korean cattle breeds along with other Asian breeds using various methods. In this study we report the genetic variation and structure of the Korean cattle breeds and their comparison with five other Asian cattle breeds along with a panel of animals from European taurine, African taurine and indicine cattle breeds. Results: Asian cattle were found to be least differentiated which reflects their recent history. Amongst the Asian breeds Hainan, which is an indicine breed, had the lowest gene diversity while Yanbian had the highest followed by Mongolian and Korean cattle. Amongst the Korean breeds Brown Hanwoo had the highest diversity followed by Brindle Hanwoo and Jeju Black. The genetic diversity in Asian cattle breeds was found comparable to the European taurines and more than the African taurines and Zebu cattle. Korean cattle breed, Brown Hanwoo was consistently found to be closer to Yanbian, a Chinese cattle breed. We found low divergence and moderate levels of genetic diversity among the native Korean breeds. Indicine introgression from Hainan was seen in other Asian breeds. From Europe, Limousin, Holstein and Hereford introgression was found in Asian breeds. Conclusions: In this study we provide a genome-wide insight into the genetic history of the native cattle breeds of Korea. The outcomes of this study will help in prioritization and designing of the conservation plans

The effect of low temperature aging on the mechanical property & phase stability of Y-TZP ceramics

STATEMENT OF PROBLEM. Recently Yttrium-stabilized tetragonal zirconia polycrystal (Y-TZP) has been introduced due to superior flexural strength and fracture toughness compared to other dental ceramic systems. Although zirconia has outstanding mechanical properties, the phenomenon of decrease in the life-time of zirconia resulted from degradation in flexural strength after low temperature aging has been reported. PURPOSE. The objective of this study was to investigate degradation of flexural strength of Y-TZP ceramics after various low temperature aging treatments and to evaluate the phase stability and micro-structural change after aging by using X-ray diffraction analysis and a scanning electron microscope (SEM). MATERIAL AND METHODS. Y-TZP blocks of Vita In-Ceram YZ (Vita Zahnfabrik, Bad Sa ¨ckingen, Germany) were prepared in 40 mm (length) x 4 mm (width) x 3 mm (height) samples. Specimens were artificially aged in distilled water by heattreatment at a temperature of 75, 100, 125, 150, 175, 200, and 225℃ for 10 hours, in order to induce the phase transformation at the surface. To measure the mechanical property, the specimens were subjected to a four-point bending test using a universal testing machine (Instron model 3365; Instron, Canton, Mass, USA). In addition, X-ray diffraction analysis (DMAX 2500; Rigaku, Tokyo, Japan) and SEM (Hitachi s4700; Jeol Ltd, Tokyo, Japan) were performed to estimate the phase transformation. The statistical analysis was done using SAS 9.1.3 (SAS institute, USA). The flexural strength data of the experimental groups were analyzed by one-way analysis of variance and to detect statistically significant differences (α= .05). RESULTS. The mean flexural strength of sintered Vita In-Ceram YZ without autoclaving was 798 MPa. When applied aging temperature at below 125℃ for 10 hours, the flexural strength of Vita In-Ceram YZ increased up to 1,161 MPa. However, at above 150℃, the flexural strength started to decrease. Although low temperature aging caused the tetragonal-to-monoclinic phase transformation related to temperature, the minimum flexural strength was above 700 MPa. CONCLUSION. The monoclinic phase started to appear after aging treatment above 100℃. With the higher aging temperature, the fraction of monoclinic phase increased. The ratio of monoclinic/tetragonal + monoclinic phase reached a plateau value, circa 75% above 175℃. The point of monoclinic concentration at which the flexural strength begins to decrease was between 12% and 54%.This work was supported by the Korea Science and Engineering Foundation (KOSEF) grant funded by the Korea government(MOST) (No. R01-2007-000-10977-0)

Prediction of Time-Dependent Chloride Diffusion Coefficients for Slag-Blended Concrete

The chloride diffusion coefficient is considered to be a key factor for evaluating the service life of ground-granulated blast-furnace slag (GGBS) blended concrete. The chloride diffusion coefficient relates to both the concrete mixing proportions and curing ages. Due to the continuous hydration of the binders, the capillary porosity of the concrete decreases and the chloride diffusion coefficient also decreases over time. To date, the dependence of chloride diffusivity on the binder hydration and curing ages of slag-blended concrete has not been considered in detail. To fill this gap, this study presents a numerical procedure to predict time-dependent chloride diffusion coefficients for slag-blended concrete. First, by using a blended cement hydration model, the degree of the binder reaction for hardening concrete can be calculated. The effects of the water to binder ratios and slag replacement ratios on the degree of the binder reaction are considered. Second, by using the degree of the binder reaction, the capillary porosity of the binder paste at different curing ages can be determined. Third, by using the capillary porosity and aggregate volume, the chloride diffusion coefficients of concrete can be calculated. The proposed numerical procedure has been verified using the experimental results of concrete with different water to binder ratios, slag replacement ratios, and curing ages

Risk of Incident Dementia According to Metabolic Health and Obesity Status in Late Life: A Population-Based Cohort Study.

CONTEXT: The risk for dementia among subjects who are obese with normal metabolic profiles, or called metabolically healthy obese (MHO), remains uninvestigated. OBJECTIVE: To determine the association between late-life metabolic health and obesity status and risk of incident dementia. DESIGN: Retrospective cohort study. SETTING: The National Health Insurance System, Republic of Korea. PATIENTS: A total of 12,296,863 adults >50 years old who underwent health examinations from 2009 to 2012 without baseline history of dementia. MAIN OUTCOME MEASURE: Incident overall dementia, Alzheimer's disease (AD), and vascular dementia (VaD). RESULTS: Among subjects ≥60 years old, 363,932 (6.4%) developed dementia during a median follow-up of 65 months (interquartile range 51 to 74 months). The MHO group showed the lowest incidence of overall dementia [hazard ratio (HR) 0.85; 95% CI, 0.84 to 0.86] and AD (HR 0.87; 95% CI, 0.86 to 0.88), but not VaD, compared with the metabolically healthy nonobese group. All components of metabolic syndrome except obesity significantly elevated the risk of dementia, and these associations were more pronounced in VaD. In particular, being underweight dramatically increased the risk of dementia. CONCLUSIONS: The MHO phenotype in late life demonstrated lower risk of overall dementia and AD but not VaD. Additional studies in other populations are warranted to elucidate current results and may predict individuals most at risk for developing dementia

Secure Software Development: Issues and Challenges

In recent years, technology has advanced considerably with the introduction of many systems including advanced robotics, big data analytics, cloud computing, machine learning and many more. The opportunities to exploit the yet to come security that comes with these systems are going toe to toe with new releases of security protocols to combat this exploitation to provide a secure system. The digitization of our lives proves to solve our human problems as well as improve quality of life but because it is digitalized, information and technology could be misused for other malicious gains. Hackers aim to steal the data of innocent people to use it for other causes such as identity fraud, scams and many more. This issue can be corrected during the software development life cycle, integrating security across the development phases, and testing of the software is done early to reduce the number of vulnerabilities that might or might not heavily impact an organisation depending on the range of the attack. The goal of a secured system software is to prevent such exploitations from ever happening by conducting a system life cycle where through planning and testing is done to maximise security while maintaining functionality of the system. In this paper, we are going to discuss the recent trends in security for system development as well as our predictions and suggestions to improve the current security practices in this industry.Comment: 20 Pages, 4 Figure