Cross talk in wavelength multiplexed holographic memories

The cross talk between wavelength-multiplexed holograms is analyzed. The signal-to-noise ratio (SNR) is calculated for a recording schedule that places the center of each image at the null (in wavelength space) of the adjacent hologram. An asymptotic closed-form expression for the minimum SNR is derived in a general reflection geometry. The reflection geometry with counterpropagating signal and reference beams is shown to have the best SNR

Minimal Permutations and 2-Regular Skew Tableaux

Bouvel and Pergola introduced the notion of minimal permutations in the study of the whole genome duplication-random loss model for genome rearrangements. Let $\mathcal{F}_d(n)$ denote the set of minimal permutations of length $n$ with $d$ descents, and let $f_d(n)= |\mathcal{F}_d(n)|$. They derived that $f_{n-2}(n)=2^{n}-(n-1)n-2$ and $f_n(2n)=C_n$, where $C_n$ is the $n$-th Catalan number. Mansour and Yan proved that $f_{n+1}(2n+1)=2^{n-2}nC_{n+1}$. In this paper, we consider the problem of counting minimal permutations in $\mathcal{F}_d(n)$ with a prescribed set of ascents. We show that such structures are in one-to-one correspondence with a class of skew Young tableaux, which we call $2$-regular skew tableaux. Using the determinantal formula for the number of skew Young tableaux of a given shape, we find an explicit formula for $f_{n-3}(n)$. Furthermore, by using the Knuth equivalence, we give a combinatorial interpretation of a formula for a refinement of the number $f_{n+1}(2n+1)$.Comment: 19 page

Addressing Health Misinformation Dissemination on Mobile Social Media

With the pervasive use of social media apps, it is now common to see that people share health related information on the mobile social platforms. The spread of health misinformation on social media apps such as Facebook and WeChat poses serious threats to individual and public health. To address this issue, we drew upon reflective-impulsive model and went beyond the traditional view of users as reasoned decision makers by arguing that the health misinformation dissemination on social media apps is primarily driven by the impulsive system (habit and avoidance orientation). To reduce the dissemination, the reflective system should be strengthened. Accordingly, we propose that the presence of a message which emphasizes the negative effects of health misinformation dissemination and/or the accountability for health misinformation dissemination will reduce users’ dissemination of the misinformation. Situational factors such as time availability, environmental noisiness and the dispositional moderator trait mindfulness will moderate the intervention effects

Efficient aircraft spare parts inventory management under demand uncertainty

In airline industries, the aircraft maintenance cost takes up about 13% of the total operating cost. It can be reduced by a good planning. Spare parts inventories exist to serve the maintenance planning. Compared with commonly used reorder point system (ROP) and forecasting methods which only consider historical data, this paper presents two non-linear programming models which predict impending demands based on installed parts failure distribution. The optimal order time and order quantity can be found by minimizing total cost. The first basic mathematical model assumes shortage period starts from mean time to failure (MTTF). An iteration method and GAMS are used to solve this model. The second improved mathematical model takes into account accurate shortage time. Due to its complexity, only GAMS is applied in solution methodology. Both models can be proved effective in cost reduction through revised numerical examples and their results. Comparisons of the two models are also discussed

Effects of IT-enabled Monitoring Systems in Online Labor Markets

This paper investigates how IT-enabled monitoring systems mitigate moral hazard in an online labor market and their effect on market competition. We exploit a quasi-experiment at Freelancer when it introduced enhanced offline tracking features in 2015. Using a large dataset including 17,827 fixed-price projects and 8,563 hourly projects, we use a difference-in-differences (DID) approach to identify the treatment effect of the implementation of IT-enabled monitoring systems on employer contractor choice, employer surplus and market competition. We found that the IT-enabled monitoring system lowers the employers’ preference for high-reputable bidders, and thus reduces the reputation premiums. Meanwhile, comparing the trend of fixed-price projects, the implementation of the monitoring systems increased the number of bids by 17.4% and increased employer surplus in hourly projects by 21.5%. Our result suggests that IT-enabled monitoring systems have a significant effect on alleviating moral hazards, reducing agency costs, and facilitating market competition

Irregular Fibonacci Conformal Blocks

This work studies Liouville conformal blocks of irregular type with the insertion of at least one level-$3$ degenerate field admitting a Fibonacci fusion rule. We algebraically derive the corresponding third-order BPZ equations for regular blocks and their modifications when a rank one irregular operator is inserted. Employing Lefschetz thimbles as integration cycles, we then successively proceed to construct integral representations and prove that they satisfy the corresponding BPZ equations. Finally, we show that taking a semiclassical limit, these integral representations can be expressed in terms of Heun functions and have correct leading behaviors consistent with conformal weights and fusion rules.Comment: 25 pages, 4 figure

The Meniscus-Guided Deposition of Semiconducting Polymers

The electronic devices that play a vital role in our daily life are primarily based on silicon and are thus rigid, opaque, and relatively heavy. However, new electronics relying on polymer semiconductors are opening up new application spaces like stretchable and self-healing sensors and devices, and these can facilitate the integration of such devices into our homes, our clothing, and even our bodies. While there has been tremendous interest in such technologies, the widespread adoption of these organic electronics requires low-cost manufacturing techniques. Fortunately, the realization of organic electronics can take inspiration from a technology developed since the beginning of the Common Era: printing. This review addresses the critical issues and considerations in the printing methods for organic electronics, outlines the fundamental fluid mechanics, polymer physics, and deposition parameters involved in the fabrication process, and provides future research directions for the next generation of printed polymer electronics

Home Bias in Online Employment

We study the nature of home bias in online employment, wherein the employer prefers workers from his/her own home country. Using a unique large-scale dataset from one of the major online labor platforms, we identify employers’ home bias in their online employment decisions. Moreover, we investigate the cause of employers’ home bias using a quasi-natural experiment wherein the platform introduces a monitoring system to facilitate employers to keep track of workers’ progress in time-based projects. After matching comparable fixed-price projects as a control group using propensity score matching, our difference-in-difference estimations show that the home bias does exist in online employment, and at least 54.0% of home bias is driven by statistical discrimination