Group automorphisms with prescribed growth of periodic points, and small primes in arithmetic progressions in intervals

We investigate the question of which growth rates are possible for the number of periodic points of a compact group automorphism. Our arguments involve a modification of Linnik's Theorem, concerning small prime numbers in arithmetic progressions which lie in intervals.Comment: 17 page

Growing in Glasgow: Innovative practices and emerging policy pathways for urban agriculture

Driven by shared concerns about climate change, social justice and health and wellbeing, Urban Agriculture (UA) is an emergent global movement. In this paper, we present an exploratory case study of UA practice on the Southside of Glasgow, UK that traced the emergence and development of four UA projects. Data from the four projects revealed a diversity of practices, including temporary gardening projects organised by local volunteers, a community and market garden operated by a charity, a food shop and vegetable distribution service run by a social enterprise, and a permanent growing space for charities and schools provided by local government. UA practitioners in Glasgow have sought to re-purpose vacant and derelict land, build social cohesion, contribute to environmental and food sustainability and provide participation space for marginalised groups. Reflecting on future avenues for research on UA in Glasgow, we have identified two broad policy pathways that are emerging both at the local level and through national legislation in Scotland to harness local urban food growing and support UA. We conclude by pointing to a need to preserve the self-organising spirit of UA in Scotland as new legislation comes into force

Stability of metal-rich very massive stars

We revisit the stability of very massive nonrotating main-sequence stars at solar metallicity, with the goal of understanding whether radial pulsations set a physical upper limit to stellar mass. Models of up to 938 solar masses are constructed with the Mesa code, and their linear stability in the fundamental mode, assumed to be the most dangerous, is analysed with a fully nonadiabatic method. Models above 100 MSun have extended tenuous atmospheres ("shelves") that affect the stability of the fundamental. Even when positive, this growth rate is small, in agreement with previous results. We argue that small growth rates lead to saturation at small amplitudes that are not dangerous to the star. A mechanism for saturation is demonstrated involving nonlinear parametric coupling to short-wavelength g modes and the damping of the latter by radiative diffusion. The shelves are subject to much more rapidly growing strange modes. This also agrees with previous results but is extended here to higher masses. The strange modes probably saturate via shocks rather than mode coupling but have very small amplitudes in the core, where almost all of the stellar mass resides. Although our stellar models are hydrostatic, the structure of their outer parts suggests that optically thick winds, driven by some combination of radiation pressure, transsonic convection, and strange modes, are more likely than pulsation in the fundamental mode to limit the main-sequence lifetime.Comment: 14 pages, 8 figures, 1 appendix; this version to be published in MNRA

Endometriosis: An Unusual Cause of Bilateral Pneumothoraces

A 27-year-old female presented to the emergency department with sudden onset shortness of breath. A diagnosis of bilateral catamenial pneumothoraces was made following chest radiograph. Catamenial pneumothorax is a recurrent spontaneous pneumothorax that occurs in 90% of affected women 24-48 hours after the onset of their menstruation; 30-50% of cases have associated pelvic endometriosis. Symptoms can be as simple as chest pain or as severe as the presentation of this patient who was initially found to be in significant respiratory distress

Octave-tunable miniature RF resonators

The development and testing of a miniaturized, high-Q, broadly tunable resonator is described. An exemplary device, with a center frequency that is continuously tunable from 1.2 to 2.6 GHz, was tested in detail. Experimental results demonstrated a resonator Q of up to 380, and typical insertion loss of -1.9 dB for a 25 MHz 3-dB bandwidth. These resonators have been used to stabilize a broadly-tunable oscillator with phase noise of -132 dBc/Hz at 100-kHz offset, with a center frequency tunable from 1.2-2.6 GHz, and a tuning speed of 1 GHz/ms

Increasing resilience of ATM networks using traffic monitoring and automated anomaly analysis

Systematic network monitoring can be the cornerstone for the dependable operation of safety-critical distributed systems. In this paper, we present our vision for informed anomaly detection through network monitoring and resilience measurements to increase the operators' visibility of ATM communication networks. We raise the question of how to determine the optimal level of automation in this safety-critical context, and we present a novel passive network monitoring system that can reveal network utilisation trends and traffic patterns in diverse timescales. Using network measurements, we derive resilience metrics and visualisations to enhance the operators' knowledge of the network and traffic behaviour, and allow for network planning and provisioning based on informed what-if analysis