The nonlinear development of the relativistic two-stream instability

The two-stream instability has been mooted as an explanation for a range of astrophysical applications from GRBs and pulsar glitches to cosmology. Using the first nonlinear numerical simulations of relativistic multi-species hydrodynamics we show that the onset and initial growth of the instability is very well described by linear perturbation theory. In the later stages the linear and nonlinear description match only qualitatively, and the instability does not saturate even in the nonlinear case by purely ideal hydrodynamic effects.Comment: 15 pages, 9 figure

Understanding Second-Person Point of View in Fiction

This thesis consists of a critical introduction followed by a short story and reflection. The critical introduction introduces and analyzes second-person point of view. The first section establishes a working definition for second-person narrative and maps out its unique relationship between narrator, protagonist, and reader. The second section explores the way second-person point of view is taught. The third and last section of the critical introduction focuses on the effects second-person point of view has on fiction narratives. The short fiction “Pregnancy and Other Dysfunctions” following the critical introduction demonstrates a narrative effectively using second-person point of view. It follows the experience of a disillusioned thirty-year-old woman in her attempt to control her situation and make herself a family. The second-person point of view illustrates how control is an illusion, and only once she loses control and gives up her expectations does she find happiness. Then I reflect on the successes and challenges of writing a story in the second-person point of view

Local magneto-shear instability in Newtonian gravity

The magneto-rotational instability (MRI) - which is due to an interplay between a sheared background and the magnetic field - is commonly considered a key ingredient for developing and sustaining turbulence in the outer envelope of binary neutron star merger remnants. To assess whether (or not) the instability is active and resolved, criteria originally derived in the accretion disk literature - thus exploiting the symmetries of such systems - are often used. In this paper we discuss the magneto-shear instability as a truly local phenomenon, relaxing common symmetry assumptions on the background on top of which the instability grows. This makes the discussion well-suited for highly dynamical environments such as binary mergers. We find that - although this is somewhat hidden in the usual derivation of the MRI dispersion relation - the instability crucially depends on the assumed symmetries. Relaxing the symmetry assumptions on the background we find that the role of the magnetic field is significantly diminished, as it affects the modes' growth but does not drive it. This suggests that we should not expect the standard instability criteria to provide a faithful indication/diagnostic of what "is actually going on" in mergers. We conclude by making contact with a suitable filtering operation, as this is key to separating background and fluctuations in highly dynamical systems.Comment: 15 pages, 1 figur

ELECTROMYOGRAPHY ANALYSIS OF FOREARM MUSCLES DURING VARIOUS YOGA POSES

The current study examined muscle activity via electromyography of the flexor carpi radialis (FCR), ulnaris (FCU), and extensor carpi radialis (ECR), ulnaris (ECU) during two variations of three separate yoga poses. Nine participants (n=9) performed three different yoga poses: plank, side-plank, and upward dog; in two separate variations, (V1) with the wrists in a passive hyperextended position, and (V2) with the wrists in a neutral position where the participants made a fist and performed the pose in that position. There were no differences between poses or variations for ECR. A difference was found between variations, but not poses for ECU. FCR and FCU were different between poses, but not variations. The only interaction was for the FCR. Due to the increased muscle activity in V2, performing yoga in V1 position may allow a yoga session to be completed with less fatigue and risk for injury

JOINT ANGLES AND FORCES ON WRIST STRUCTURES DURING VARIATIONS OF YOGA POSES

The current study analysed joint angles of the wrists and forces on the structures in the hands and wrists in a hyperextended position and a neutral position during three different yoga poses. Participants (n = 9) performed three yoga poses (plank, side plank, and upward dog), with their wrists in a hyperextended position (H) and a neutral position (N). Each pose was completed three times for 10 seconds in H and N, for a total of six trials per pose. A two-way Repeated Measures ANOVA found significant differences in both wrist joint angles and GRF between H and N. Due to the suggested path transmission of forces, as well as the increased longitudinal loading that comes with wrist hyperextension, it is recommended that plank, side plank, and upward dog be performed in a neutral wrist position

Facebook as a recruitment tool for adolescent health research: A systematic review

BACKGROUND: Researchers are increasingly using social media to recruit participants to surveys and clinical studies. However, the evidence of the efficacy and validity of adolescent recruitment through Facebook is yet to be established. OBJECTIVE: To conduct a systematic review of the literature on the use of Facebook to recruit adolescents for health research. DATA SOURCES: Nine electronic databases and reference lists were searched for articles published between 2004 and 2013. STUDY ELIGIBILITY CRITERIA: Studies were included in the review if: 1) participants were aged 10 to 18 years, 2) studies addressed a physical or mental health issue, 3) Facebook was identified as a recruitment tool, 4) recruitment details using Facebook were outlined in the methods section and considered in the discussion, or information was obtained by contacting the authors, 5) results revealed how many participants were recruited using Facebook, and 6) studies addressed how adolescent consent and/or parental consent was obtained. STUDY APPRAISALS AND SYNTHESIS METHODS: Titles, abstracts, and keywords were scanned and duplicates removed by 2 reviewers. Full text was evaluated for inclusion criteria, and 2 reviewers independently extracted data. RESULTS: The search resulted in 587 publications, of which 25 full-text papers were analyzed. Six studies met all the criteria for inclusion in the review. Three recruitment methods using Facebook was identified: 1) paid Facebook advertising, 2) use of the Facebook search tool, and 3) creation and use of a Facebook Page. CONCLUSIONS: Eligible studies described the use of paid Facebook advertising and Facebook as a search tool as methods to successfully recruit adolescent participants. Online and verbal consent was obtained from participants recruited from Facebook

THE EFFECT OF SHOE TYPE ON VARIOUS KINETIC AND KINEMATIC VARIABLES DURING STEP-UP AND STEP-DOWN MOTIONS

The purpose of this study was to examine the effect of shoe type on the biomechanical responses to a stepping task. Participants (n = 8) performed six two minute stepping trials at a stepping rate of 72 bpm; 3 trials in hiking boots and 3 trials in hiking shoes. Lower limb joint angles and moments were calculated using Visual 3D. No significant differences were found in step down peak ground reaction forces (GRF), ankle, knee, and hip range of motion (ROM), joint moments, joint flexion at step down contact, or toe clearance height between footwear conditions. Due to the lack of differences found between footwear conditions, the use of either a hiking shoe or boot may not result in an increased risk of injury, therefore leaving the choice of footwear to the hiker’s personal preference

Crustal failure during binary inspiral

We present the first fully relativistic calculations of the crustal strain induced in a neutron star by a binary companion at the late stages of inspiral, employing realistic equations of state for the fluid core and the solid crust. We show that while the deep crust is likely to fail only shortly before coalescence, there is a large variation in elastic strain, with the outermost layers failing relatively early on in the inspiral. We discuss the significance of the results for both electromagnetic and gravitational-wave astronomy.Comment: 5 pages, 3 eps figure

Access 3 project protocol: Young people and health system navigation in the digital age: A multifaceted, mixed methods study

© 2017 Article author(s). Background: The integration of digital technology into everyday lives of young people has become widespread. It is not known whether and how technology influences barriers and facilitators to healthcare, and whether and how young people navigate between face-to-face and virtual healthcare. To provide new knowledge essential to policy and practice, we designed a study that would explore health system access and navigation in the digital age. The study objectives are to: (1) describe experiences of young people accessing and navigating the health system in New South Wales (NSW), Australia; (2) identify barriers and facilitators to healthcare for young people and how these vary between groups; (3) describe health system inefficiencies, particularly for young people who are marginalised; (4) provide policy-relevant knowledge translation of the research data. Methods and analysis: This mixed methods study has four parts, including: (1) a cross-sectional survey of young people (12-24 years) residing in NSW, Australia; (2) a longitudinal, qualitative study of a subsample of marginalised young people (defined as young people who: identify as Aboriginal and/or Torres Strait Islander; are experiencing homelessness; identify as sexuality and/or gender diverse; are of refugee or vulnerable migrant background; and/or live in rural or remote NSW); (3) interviews with professionals; (4) a knowledge translation forum. Ethics and dissemination: Ethics approvals were sought and granted. Data collection commenced in March 2016 and will continue until June 2017. This study will gather practice and policy-relevant intelligence about contemporary experiences of young people and health services, with a unique focus on five different groups of marginalised young people, documenting their experiences over time. Access 3 will explore navigation around all levels of the health system, determine whether digital technology is integrated into this, and if so how, and will translate findings into policy-relevant recommendations