Local Popularity: A Double-edged Tool in Platform Operation

Although displaying local popularity is wildly adopted by major platforms, the actual effect of such information cues on motivating users has not been documented. Findings from a field experiment suggest that local popularity effectively motivates users to invite more friends but surprisingly reduces users’ self-participation. Social conformity theory may account for such effects: local information encourages users to invite their local friends, but such effect is limited to users from small cities since users in a relatively small community are more bonded and less likely to reject the invitation due to social pressure. Meanwhile, local information attenuates the power of popularity (e.g., fewer registered users in the local area) and ultimately discourages users\u27 self-participation. This study deepens our understanding of displaying popularity cue in improving platform operation, based on which we suggest that practitioners should be cautious about the persuasive power of such information cues in location-based marketing

A closed economy DSGE model with occasionally binding cash-in-advance constraints

his thesis is planned to investigate whether endogenously binding cash-in-advance (CIA) constraints helps to explain the persistent liquidity traps in the US since the 2008 financial crisis. It extends the theoretical general equilibrium analysis by Dixon and Pourpourides (2016) to build a closed economy DSGE model. The model is evaluated based on the calibration and is estimated by the method proposed by Guerrieri and Iacoviello (2015, 2017) using filtered data in the period of 1985Q1 to 2017Q4 for the United States. When money is the only asset, an increase in money supply followed by a technological innovation triggers a nonbinding CIA constraint, which can cause a consumption boom. The changes in the inflation rate are the main driving force for the nonbinding CIA constraints. The periods when the CIA constraint is slack follows the waves of quantitative easing policies. However, when capital and bonds are introduced, a nonbinding CIA constraint fails to generate a consumption boom. Two ways of modelling monetary policy, money growth rule and interest rate feedback rule with zero-lower bound (ZLB), are compared. Money, which serves as a safe asset, depresses output and its components. Things are even worse when the monetary policy is set via an interest rate feedback rule with ZLB as the nominal interest rate becomes the main driving force for nonbinding CIA constraints. When the ZLB already binds, an increase in money supply loses its ability to stimulate the economy and the liquidity traps are more persistent. The model when both occasionally binding CIA constraints and ZLB are included successfully matches the data, especially for the period after the 2008 global crisis. The Friedman rule is still optimal, but the monetary authority should consider subsidizing or taxing on specific sectors instead of conducting open market operations that raise the base money in the whole economy

Stellar Bars in Spinning Halos: Delayed Buckling and Absence of Slowdown

We use high resolution numerical simulations in order to analyze the stellar bar evolution in spinning dark matter (DM) halos. Previous works have shown that the halo spin has a substantial effect on the bar evolution and can lead to bar dissolution following the vertical buckling instability. Here, we invoke the DM spin sequence, $\lambda=0-0.09$, and study the effect of DM density along this $\lambda$-sequence by varying the compactness of DM halo. We find that (1) varying the DM density has a profound effect on the stellar bar evolution along the $\lambda$-sequence, namely, on its amplitude, pattern speed, buckling time, etc.; (2) For $\lambda\gtrsim 0.04$, the buckling instability has been delayed progressively, and does not occur when the bar has reached its maximal strength; (3) Instead, stellar bars remain near maximal strength, and their amplitude plateau stage extends over $\sim 1-7$ Gyr, terminating with the buckling instability; (4) Although stellar bars remain strong during the plateau, their pattern speed stays nearly constant. The reason for this unusual behavior of stellar bars follows from the highly reduced gravitational torques which they experience due to the DM bar being aligned with the stellar bar. The performed orbital analysis shows that the delayed buckling results from a slow evolution of stellar oscillations along the bar major and vertical axes -- thus postponing the action of the vertical 2:1 resonance which pumps the rotational energy into vertical motions; (5) Peanut/boxy shaped bulges form at the beginning of the plateau and grow with time; (6) Strong stellar bars in spinning halos can avoid fast braking, resolving the long standing discrepancy between observations and $N$-body simulations. This behavior of stellar bars along the $\lambda$- and DM density-sequences, reveals a wealth of stellar bar properties which require additional study.Comment: 12 pages, 16 figures, submitted to MNRA

Surgical Management of Migraine Headaches

Although migraines are experienced by a significant portion of the population, current medical therapies often fail to completely alleviate the symptoms of many migraine sufferers, leading to significant residual disability. Within the last decade, migraine surgery has arisen as a viable option for patients who have exhausted all other medical treatments. Despite early resistance in the headache care community, it has become more accepted due to an increasing number of studies demonstrating efficacy and safety, and increasing evidence supporting the influence of peripheral nerves in the progression of migraine pathophysiology. Yet, it remains crucial to carefully select appropriate surgical candidates based on the assessment of various factors such as medication use, pain distribution, and any other medical conditions that may contribute to headache. It is equally important to ensure that the patient has a strong relationship with a neurologist for optimal medical management and postoperative medical support. After the appropriate trigger sites are identified, various techniques can be used to decompress the involved larger nerves, avulse the smaller nerves, and address any intranasal pathology that could be causing migraines

RePaint-NeRF: NeRF Editting via Semantic Masks and Diffusion Models

The emergence of Neural Radiance Fields (NeRF) has promoted the development of synthesized high-fidelity views of the intricate real world. However, it is still a very demanding task to repaint the content in NeRF. In this paper, we propose a novel framework that can take RGB images as input and alter the 3D content in neural scenes. Our work leverages existing diffusion models to guide changes in the designated 3D content. Specifically, we semantically select the target object and a pre-trained diffusion model will guide the NeRF model to generate new 3D objects, which can improve the editability, diversity, and application range of NeRF. Experiment results show that our algorithm is effective for editing 3D objects in NeRF under different text prompts, including editing appearance, shape, and more. We validate our method on both real-world datasets and synthetic-world datasets for these editing tasks. Please visit https://repaintnerf.github.io for a better view of our results.Comment: IJCAI 2023 Accepted (Main Track

Exploring Downvoting in Blockchain-based Online Social Media Platforms

In recent years, Blockchain-based Online Social Media (BOSM) platforms have evolved fast due to the advancement of blockchain technology. BOSM can effectively overcome the problems of traditional social media platforms, such as a single point of trust and insufficient incentives for users, by combining a decentralized governance structure and a cryptocurrency-based incentive model, thereby attracting a large number of users and making it a crucial component of Web3. BOSM allows users to downvote low-quality content and aims to decrease the visibility of low-quality content by sorting and filtering it through downvoting. However, this feature may be maliciously exploited by some users to undermine the fairness of the incentive, reduce the quality of highly visible content, and further reduce users' enthusiasm for content creation and the attractiveness of the platform. In this paper, we study and analyze the downvoting behavior using four years of data collected from Steemit, the largest BOSM platform. We discovered that a significant number of bot accounts were actively downvoting content. In addition, we discovered that roughly 9% of the downvoting activity might be retaliatory. We did not detect any significant instances of downvoting on content for a specific topic. We believe that the findings in this paper will facilitate the future development of user behavior analysis and incentive pattern design in BOSM and Web3

Management of Migraine Headaches: OnabotulinumtoxinA Injection

Chronic migraines are a common debilitating headache disorder. Recently, there has been increasing interest in the use of onabotulinumtoxinA as a preventative treatment, as studies have shown significant benefits. In line with current accepted theories on the pathophysiology of migraines, the toxin works by both direct and indirect means to prevent peripheral and central nerve sensitization. While efficacy has been established, the technique for extracranial delivery of onabotulinumtoxinA continues to see changes in an effort to seek better outcomes. The PREEMPT injection protocol is the original injection paradigm design targeting broad muscle groups. The ART injection paradigm offers the ability to deliver onabotulinumtoxinA closer to culprit nerves, thus increasing its effect and also decreasing adverse effects. OnabotulinumtoxinA is an effective and well-tolerated option for selective patients seeking relief from migraine headaches

The Origin of Buckling Instability in Galactic Bars: Searching for the Scapegoat

The buckling process in stellar bars is full of unsolved issues. We analyze the origin of the buckling instability in stellar bars using high-resolution N-body simulations. Previous studies have promoted the nonresonant firehose instability to be responsible for the vertical buckling. We have analyzed the buckling process in terms of the resonant excitation of stellar orbits in the bar, which pumps energy into vertical oscillations. We find that (1) the buckling is associated with an abrupt increase in the central mass concentration and triggers velocities along the bar and along its rotation axis. The velocity field projected on one of the main axes forms circulation cells and increases vorticity, which are absent in firehose instability; (2) The bending amplitude is nonlinear when measured by isodensity contours or curvature of the Laplace plane, which has a substantial effect on the stellar motions; (3) In the linear description, the planar and vertical 2:1 resonances appear only with the buckling and quickly reach the overlapping phase, thus supporting the energy transfer; (4) Using nonlinear orbit analysis, we analyze the stellar oscillations along the bar and along the rotation axis and find that stars cross the vertical 2:1 resonance simultaneously with the buckling. The overlapping planar and vertical 2:1 resonances trapping more than 25% of the bar particles provide the 'smoking gun' pointing to a close relationship between the bending of stellar orbits and the resonant action -- these particles provide the necessary ingredient assuring the cohesive response in the growing vertical asymmetry. We conclude that resonant excitation is important in triggering the buckling instability, and the contribution from the firehose instability should be reevaluated. Finally, we discuss some observational implications of buckling.Comment: Submitted to MNRAS, 16 pages, 18 figure