Flux Noise in MgB2 Thin Films

We have performed flux noise and AC-susceptibility measurements on two 400 nm thick MgB$_2$ films. Both measurement techniques give information about the vortex dynamics in the sample, and hence the superconducting transition, and can be linked to each other through the fluctuation-dissipation-theorem. The transition widths for the two films are 0.3 and 0.8 K, respectively, and the transitions show a multi step-like behavior in the AC-susceptibility measurements. The same phenomenon is observed in the flux noise measurements through a change in the frequency dependence of the spectral density at each step in the transition. The results are discussed and interpreted in terms of vortices carrying an arbitrary fraction of a flux quantum as well as in terms of different macroscopic regions in the films having slightly different compositions, and hence, different critical temperatures.Comment: 8 pages, 4 figures, conference contribution to "Fluctuations and Noise", Santa Fe, New mexico 1-4 june 200

The Economic Impact of Government Policy on Market Prices of Low-Fat Pork in South Korea : A Quasi-Experimental Hedonic Price Approach

The implementation of government policy can have an influence on market environment and market prices of pork in consequence. In South Korea, consumers prefer high-fat pork cuts due to the prevalence of roosting pork over a hot grill. This paper examines the impact of the government policy which aims to increase the consumption of low-fat pork cuts because of the concerns regarding asymmetric consumption between high-fat and low-fat pork cuts. Using hedonic price methods combined with quasi-experimental approaches we estimate the subsequent impact of food policy on the price of low-fat pork cuts using a time series of sales data. This study utilized an effective approach which has been widely employed for policy evaluation to produce plausible estimates of the economic values generated by the government policy. We find the existence of market segmentation and different impacts of the policy between markets. While the market price for high-fat pork cuts has remained stable, the price for low-fat pork cuts has slightly increased since the policy has been implemented. This paper illustrates that government’s policy can be a good strategy to maintain sustainability of the food industry by improving the balance in pork consumption and the management of stocks

Growth of superconducting MgB2 thin films via postannealing techniques

We report the effect of annealing on the superconductivity of MgB2 thin films as functions of the postannealing temperature in the range from 700 C to 950 C and of the postannealing time in the range from 30 min to 120 min. On annealing at 900 C for 30 min, we obtained the best-quality MgB2 films with a transition temperature of 39 K and a critical current density of ~ 10^7 A/cm^2. Using the scanning electron microscopy, we also investigated the film growth mechanism. The samples annealed at higher temperatures showed the larger grain sizes, well-aligned crystal structures with preferential orientations along the c-axis, and smooth surface morphologies. However, a longer annealing time prevented the alignment of grains and reduced the superconductivity, indicating a strong interfacial reaction between the substrate and the MgB2 film.Comment: 7 pages, 4 figures include

Cyber Black Box: Network intrusion forensics system for collecting and preserving evidence of attack

Once the system is compromised, the forensics and investigation are always executed after the attacks and the loss of some useful instant evidence. Since there is no log information necessary for analyzing an attack cause after the cyber incident occurs, it is difficult to analyze the cause of an intrusion even after an intrusion event is recognized. Moreover, in an advanced cyber incident such as advanced persistent threats, several months or more are expended in only analyzing a cause, and it is difficult to find the cause with conventional security equipment. In this paper, we introduce a network intrusion forensics system for collecting and preserving the evidence of an intrusion, it is called Cyber Black Box that is deployed in Local Area Network environment. It quickly analyzes a cause of an intrusion event when the intrusion event occurs, and provides a function of collecting evidence data of the intrusion event. The paper also describes the experimental results of the network throughput performance by deploying our proposed system in an experimental testbed environment