One-Armed Spiral Waves in Galaxy Simulations with Counter-Rotating Stars

Motivated by observations of disk galaxies with counter-rotating stars, we have run two-dimensional, collisionless N-body simulations of disk galaxies with significant counter-rotating components. For all our simulations the initial value of Toomre's stability parameter was Q = 1.1. The percentage of counter-rotating particles ranges from 25% to 50%. A stationary one-arm spiral wave is observed to form in each run, persisting from a few to five rotation periods, measured at the half-mass radius. In one run, the spiral wave was initially a leading arm which subsequently transformed into a trailing arm. We also observed a change in spiral direction in the run initially containing equal numbers of particles orbiting in both directions. The results of our simulations support an interpretation of the one armed waves as due to the two stream instability.Comment: 13 pages, 4 figure

Evaluation of the Site Investigation and Construction Related Aspects of the Milwaukee\u27s Crosstown Deep Tunnel

The excavation of the 21,300 foot long, 32.33 foot diameter Crosstown Phase I Tunnel was completed by tunnel boring machine at an average rate of 108 feet per 3 shift day. No geologic conditions were encountered which were sufficiently adverse to impede the work. The geotechnical report combined with contract provisions prevented the unusual conditions encountered from becoming issues that delayed the work. It is probable that the monetary aspects related to these unusual conditions can be equitably resolved using the geotechnical data “base line” portrayed in the geotechnical report

Patronin-mediated minus end growth is required for dendritic microtubule polarity.

Microtubule minus ends are thought to be stable in cells. Surprisingly, in Drosophila and zebrafish neurons, we observed persistent minus end growth, with runs lasting over 10 min. In Drosophila, extended minus end growth depended on Patronin, and Patronin reduction disrupted dendritic minus-end-out polarity. In fly dendrites, microtubule nucleation sites localize at dendrite branch points. Therefore, we hypothesized minus end growth might be particularly important beyond branch points. Distal dendrites have mixed polarity, and reduction of Patronin lowered the number of minus-end-out microtubules. More strikingly, extra Patronin made terminal dendrites almost completely minus-end-out, indicating low Patronin normally limits minus-end-out microtubules. To determine whether minus end growth populated new dendrites with microtubules, we analyzed dendrite development and regeneration. Minus ends extended into growing dendrites in the presence of Patronin. In sum, our data suggest that Patronin facilitates sustained microtubule minus end growth, which is critical for populating dendrites with minus-end-out microtubules

Chinese computational propaganda: automation, algorithms and the manipulation of information about Chinese politics on Twitter and Weibo

A 2016 review of literature about automation, algorithms and politics identified China as the foremost area in which further research was needed because of the size of its population, the potential for Chinese algorithmic manipulation in the politics of other countries, and the frequency of exportation of Chinese software and hardware. This paper contributes to the small body of knowledge on the first point (domestic automation and opinion manipulation) and presents the first piece of research into the second (international automation and opinion manipulation). Findings are based on an analysis of 1.5 million comments on official political information posts on Weibo and 1.1 million posts using hashtags associated with China and Chinese politics on Twitter. In line with previous research, little evidence of automation was found on Weibo. In contrast, a large amount of automation was found on Twitter. However, contrary to expectations and previous news reports, no evidence was found of pro-Chinese-state automation on Twitter. Automation on Twitter was associated with anti-Chinese-state perspectives and published in simplified Mandarin, presumably aimed at diasporic Chinese and mainland users who ‘jump the wall’ to access blocked platforms. These users come to Twitter seeking more diverse information and an online public sphere but instead they find an information environment in which a small number of anti-Chinese-state voices are attempting to use automation to dominate discourse. Our understanding of public conversation on Twitter in Mandarin is extremely limited and, thus, this paper advances the understanding of political communication on social media

The Brexit Botnet and User-Generated Hyperpartisan News

In this paper we uncover a network of Twitterbots comprising 13,493 accounts that tweeted the U.K. E.U. membership referendum, only to disappear from Twitter shortly after the ballot. We compare active users to this set of political bots with respect to temporal tweeting behavior, the size and speed of retweet cascades, and the composition of their retweet cascades (user-to-bot vs. bot-to-bot) to evidence strategies for bot deployment. Our results move forward the analysis of political bots by showing that Twitterbots can be effective at rapidly generating small to medium-sized cascades; that the retweeted content comprises user-generated hyperpartisan news, which is not strictly fake news, but whose shelf life is remarkably short; and, finally, that a botnet may be organized in specialized tiers or clusters dedicated to replicating either active users or content generated by other bots

Comparison of the application of low concentration and 80% phenol solution in pilonidal sinus disease

Objectives Many conservative methods have been applied in the treatment of pilonidal sinus disease (PSD). The most commonly used conservative treatment is 80% phenol solution. Our observations demonstrated that 80% phenol solution caused much destruction in the sacrococcygeal region. Design In this study low concentrations of phenol were used with the aim of reducing the unwanted side-effects of high-concentration phenol without reducing the therapeutic effects. Participants We treated 112 patients (18 women, 94 men) with PSD using phenol solution. Patients were divided into two groups: Group A was treated with a 40% solution of phenol solution, and Group B was treated with an 80% solution of phenol solution. Setting All patients were treated on an outpatient basis. One mL of low (40%) or high (80%) concentration phenol solution was injected into the main sinus orifice. During the check it was observed and noted whether there was skin necrosis, fatty tissue necrosis or abscesses. Main outcome measures The mean age was 27.4 years (6–44). The median length of symptoms was seven months (0.5–132). In the 2.8 years (1–6) of mean follow-up period, the disease recurred in 13 (11.6%) patients. Results This treatment procedure was well-tolerated by all the patients except for those who had unwanted results. No patients in group A had skin necrosis, and only one had abscesses. In group B two patients had abscesses, and three had skin necrosis. Fatty tissue necrosis was seen in one patient in Group A and in five patients in Group B. Recurrence rates were four (7.4%) cases in Group A and nine (15.5%) cases in Group B. Conclusions It is possible to treat patients in a shorter time with a considerably smaller loss of working time, since the destruction of peripilonidal adipose tissue and skin is less. Therefore, the use of low-concentration phenol solution is an option to be considered in the treatment of PSD.PubMe

Attractiveness of a Four-component Pheromone Blend to Male Navel Orangeworm Moths

The attractiveness to male navel orangeworm moth, Amyelois transitella, of various combinations of a four-component pheromone blend was measured in wind-tunnel bioassays. Upwind flight along the pheromone plume and landing on the odor source required the simultaneous presence of two components, (11Z,13Z)-hexadecadienal and (3Z,6Z,9Z,12Z,15Z)-tricosapentaene, and the addition of either (11Z,13Z)-hexadecadien-1-ol or (11Z,13E)-hexadecadien-1-ol. A mixture of all four components produced the highest levels of rapid source location and source contact. In wind-tunnel assays, males did not seem to distinguish among a wide range of ratios of any of the three components added to (11Z,13Z)-hexadecadienal. Dosages of 10 and 100 ng of the 4-component blend produced higher levels of source location than dosages of 1 and 1,000 ng