Asymmetric, helical and mirror-symmetric travelling waves in pipe flow

New families of three-dimensional nonlinear travelling waves are discovered in pipe flow. In contrast to known waves (Faisst & Eckhardt Phys. Rev. Lett. 91, 224502 (2003), Wedin & Kerswell, J. Fluid Mech. 508, 333 (2004)), they possess no rotational symmetry and exist at much lower Reynolds numbers. Particularly striking is an `asymmetric mode' which has one slow streak sandwiched between two fast streaks located preferentially to one side of the pipe. This family originates in a pitchfork bifurcation from a mirror-symmetric travelling wave which can be traced down to a Reynolds number of 773. Helical and non-helical rotating waves are also found emphasizing the richness of phase space even at these very low Reynolds numbers. The delay in Reynolds number from when the laminar state ceases to be a global attractor to turbulent transition is then even larger than previously thought.Comment: 4 pages, 7 figures (2 at low resolution

Project Dawdler: a Proposal in Response to a Low Reynolds Number Station Keeping Mission

In direct response to Request for Proposals: Flight at very low Reynolds numbers - a station keeping mission, the members of Design Squad E present Project Dawdler: a remotely-piloted airplane supported by an independently controlled take-off cart. A brief introduction to Project Dawdler's overall mission and design, is given. The Dawdler is a remotely-piloted airplane designed to fly in an environmentally-controlled closed course at a Reynolds number of 10(exp 5) and at a cruise velocity of 25 ft/s. The two primary goals were to minimize the flight Reynolds number and to maximize the loiter time. With this in mind, the general design of the airplane was guided by the belief that a relatively light aircraft producing a fairly large amount of lift would be the best approach. For this reason the Dawdler utilizes a canard rather than a conventional tail for longitudinal control, primarily because the canard contributes a positive lift component. The Dawdler also has a single vertical tail mounted behind the wing for lateral stability, half of which is used as a rudder for yaw control. Due to the fact that the power required to take-off and climb to altitude is much greater than that required for cruise flight and simple turning maneuvers, it was decided that a take-off cart be used. Based on the current design, there are two unknowns which could possibly threaten the success of Project Dawdler. First, the effect of the fully-movable canard with its large appropriation of total lift on the performance of the plane, and secondly, the ability of the take-off procedure to go as planned are examined. These are questions which can only be answered by a prototype

Savannah Hockey Classic Attendance Motivation

The Savannah Hockey Classic has become a very successful annual university club hockey team tournament. The 21st edition of the tournament was held in January 2020 in Savannah, Ga. featuring the Georgia Institute of Technology, University of Florida, Florida State University, and University of Georgia club hockey teams—the same teams that have comprised the tournament for many years. This study utilized Personal Investment Theory (Braskamp, 1986) and the SPEED scale (Funk, Filo, Beaton, & Pritchard, 2009) for attendance motivation assessment. Social interaction motivations were significantly higher for county residents, spectators attending with friends, spectators attending with family, and past Savannah Hockey Classic attendees. Motivations related to athlete performance were significantly higher for those who had attended the event in the past. Excitement based motivations were greater for those who had attended the event in the past as well as for those who identified as a fan of one of the teams. There were significant differences related to the esteem and diversion constructs for those who had a team rooting interest. The article fills a gap in the literature by providing the first study of club hockey attendance motivations

HIV Research Year in Review in Haiti

Introduction For this issue of the Epidemiologic Surveillance Bulletin, we summarize the prior year’s research on populations living with HIV (PLWH) in Haiti for World AIDS Day 2020. Methods We retrieved 50 articles from PubMed (pubmed.gov) for articles written in English using the search term [Haiti* AND (HIV OR human immunodeficiency virus OR AIDS)] from December 2019 to November 19, 2020 (approximately 1 year). We included studies that of cohorts of people living with HIV in Haiti, patients enrolled from Haiti in multi-country clinical studies and studies involving populations at substantial risk of HIV in Haiti. We excluded studies of Haitian populations in other countries, study protocols, perspectives, and opinion articles. The final review contains summaries of 28 studies. We grouped into relevant themes when possible and summarized each paper

Irritable Bowel Syndrome patients exhibit depressive and anxiety scores in the subsyndromal range

Irritable bowel syndrome (IBS) patients frequently experience affective disorders and psychiatric outpatients frequently meet criteria for IBS. The exact nature of this co-morbidity is not clear. 34 patients with Rome-II diagnosed IBS were recruited from a Gastroenterology clinic. Patients with social anxiety disorder (10 SSRI-remitted and 7 untreated subjects) were used as a psychiatric comparison, 28 normal subjects from our register were included as a fourth group (Volunteers). Depressive and anxiety symptoms were measured by the Beck Depression Inventory (BDI) and Spielberger Trait Anxiety Inventory (STAI), respectively. Personality traits were measured with the Swedish universities Scales of Personality (SSP). IBS subjects had BDI and STAI scores intermediate between those of volunteers and patients, despite their lack of a co-morbid psychiatric diagnosis. A principle component factor analysis of the SSP dataset corresponded closely to the solution published with other samples. ANOVA revealed significant between-group differences for 7 of the 13 SSP variables