Non-random dispersal in the butterfly Maniola jurtina: implications for metapopulation models

The dispersal patterns of animals are important in metapopulation ecology because they affect the dynamics and survival of populations. Theoretical models assume random dispersal but little is known in practice about the dispersal behaviour of individual animals or the strategy by which dispersers locate distant habitat patches. In the present study, we released individual meadow brown butterflies (Maniola jurtina) in a non-habitat and investigated their ability to return to a suitable habitat. The results provided three reasons for supposing that meadow brown butterflies do not seek habitat by means of random flight. First, when released within the range of their normal dispersal distances, the butterflies orientated towards suitable habitat at a higher rate than expected at random. Second, when released at larger distances from their habitat, they used a non-random, systematic, search strategy in which they flew in loops around the release point and returned periodically to it. Third, butterflies returned to a familiar habitat patch rather than a non-familiar one when given a choice. If dispersers actively orientate towards or search systematically for distant habitat, this may be problematic for existing metapopulation models, including models of the evolution of dispersal rates in metapopulations

Multipactor experiment on a dielectric surface

A novel experiment to investigate single-surface multipactor on a dielectric surface was developed and tested. The compact apparatus consists of a small brass microwave cavity in a high vacuum system. The cavity is ∼15 cm in length with an outer diameter of ∼10 cm. A pulsed variable frequency microwave source at ∼2.4 GHz, 2 kW peak excites the TE111TE111 mode with a strong electric field parallel to a dielectric plate (∼0.2 cm thickness) that is inserted at midlength of the cavity. The microwave pulses are monitored by calibrated microwave diodes. An electron probe measures electron current and provides temporal measurements of the multipactor electron current with respect to the microwave pulses. Phosphor on the dielectric surface is used to detect multipactor electrons by photoemission. The motivation of this experiment is to test recent theoretical calculations of single-surface multipactor on a dielectric. © 2001 American Institute of Physics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/71183/2/RSINAK-72-7-3095-1.pd

The impact of fretting wear on structural dynamics: Experiment and simulation

This paper investigates the effects of fretting wear on frictional contacts. A high frequency friction rig is used to measure the evolution of hysteresis loops, friction coefficient and tangential contact stiffness over time. This evolution of the contact parameters is linked to significant changes in natural frequencies and damping of the rig. Hysteresis loops are replicated by using a Bouc-Wen modified formulation, which includes wear to simulate the evolution of contact parameters and to model the evolving dynamic behaviour of the rig. A comparison of the measured and predicted dynamic behaviour demonstrates the feasibility of the proposed approach and highlights the need to consider wear to accurately capture the dynamic response of a system with frictional joints over its lifetime

The impact of fretting wear on structural dynamics: Experiment and simulation

This paper investigates the effects of fretting wear on frictional contacts. A high frequency friction rig is used to measure the evolution of hysteresis loops, friction coefficient and tangential contact stiffness over time. This evolution of the contact parameters is linked to significant changes in natural frequencies and damping of the rig. Hysteresis loops are replicated by using a Bouc-Wen modified formulation, which includes wear to simulate the evolution of contact parameters and to model the evolving dynamic behaviour of the rig. A comparison of the measured and predicted dynamic behaviour demonstrates the feasibility of the proposed approach and highlights the need to consider wear to accurately capture the dynamic response of a system with frictional joints over its lifetime

Energy deposition in metals by laser-guided discharges

Experimental and theoretical results are reported concerning energy deposition on metal surfaces by laser-guided discharges (LGD) in argon and nitrogen at atmospheric pressure. These experiments have demonstrated effective guidance of 30-kV discharges for lengths up to 6 cm. The electron temperature and density have been measured spectroscopically for LGD plasmas. Scaling of the melted metallic mass has been studied as a function of discharge circuit parameters for both argon and nitrogen. Results show that laser-guided discharges in nitrogen couple energy to metal samples more efficiently than argon discharges with identical electrical parameters. This experimentally observed difference in energy deposition has been shown to be in good agreement with a theoretical model which accounts for the recombination energy of nitrogen on the metallic surface. Melting has been accomplished by LGDs in copper, iron, aluminum, and titanium foils. Laser-guided discharges have also bored holes and deposited surface layers of aluminum and titanium onto stainless steel.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/45475/1/11090_2004_Article_BF00564625.pd

Production of XeO * in a CW microwave discharge

A low-power CW microwave discharge at 2.45 GHz was used to produce XeO * excimer molecules. It was found that a total gas pressure between 5 and 20 Torr, absorbed power of about 20–100 W, and an oxygen-to-xenon ratio of 1∶100 maximized the XeO( 1 S− 1 D) green emission at 5200 to 5600 Å. The XeO * emission appeared in the cooler parts of the discharge near the containment tube walls and in the electric field nodes of the TM 012 resonant mode.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/45480/1/11090_2005_Article_BF01023916.pd

Knowledge of and adherence to radiographic guidelines for low back pain: a survey of chiropractors in Newfoundland and Labrador, Canada

Background: Low back pain (LBP) rarely requires routine imaging of the lumbar spine in the primary care setting, as serious spinal pathology is rare. Despite evidence-based clinical practice guidelines recommending delaying imaging in the absence of red flags, chiropractors commonly order imaging outside of these guidelines. The purpose of this study was to survey chiropractors to determine the level of knowledge, adherence to, and beliefs about, clinical practice guidelines related to the use of lumbar radiography for LBP in Newfoundland and Labrador (NL), Canada. Methods: A cross-sectional survey of chiropractors in NL (n = 69) was conducted between May and June 2018, including questions on demographics, awareness of radiographic guidelines, and beliefs about radiographs for LBP. We assessed behavioural simulation using clinical vignettes to determine levels of adherence to LBP guideline recommendations. Results: The response rate was 77% (n = 53). Half of the participants stated they were aware of current radiographic guideline recommendations, and one quarter of participants indicated they did not use guidelines to inform clinical decisions. The majority of participants agreed that x-rays of the lumbar spine are useful for patients with suspected pathology, are indicated when a patient is non-responsive to 4 weeks of conservative treatment for LBP, and when there are neurological signs associated with LBP. However, a small proportion indicated that there is a role for full spine x-rays (~ 21%), x-rays to evaluate patients with acute LBP (~ 13%), and that patient expectations play a role in decision making (4%). Adherence rate to radiographic guidelines measured using clinical vignettes was 75%. Conclusions: While many chiropractors in this sample reported being unsure of specific radiographic guidelines, the majority of respondents adhered to guideline recommendations measured using clinical vignettes. Nonetheless, a small proportion still hold beliefs about radiographs for LBP that are discordant with current radiographic guidelines. Future research should aim to determine barriers to guideline uptake in this population in order to design and evaluate tailored knowledge translation strategies to reduce unnecessary LBP imaging. © 2021, The Author(s)

Exploring factors influencing chiropractors’ adherence to radiographic guidelines for low back pain using the Theoretical Domains Framework

Background The inappropriate use of lumbar spine imaging remains common in primary care despite recommendations from evidence-based clinical practice guidelines to avoid imaging in the absence of red flags. This study aimed to explore factors influencing ordering behaviours and adherence to radiographic guidelines for low back pain (LBP) in chiropractors in Newfoundland and Labrador (NL), Canada. Methods We conducted two focus groups in December 2018 with chiropractors in different regions of NL (eastern, n = 8; western, n = 4). An interview guide based on the Theoretical Domains Framework (TDF) served to identify perceived barriers to, and enablers of, target behaviours of guideline adherence and managing LBP without X-rays. We conducted thematic analysis of chiropractors’ statements into relevant theoretical domains, followed by grouping of similar statements into specific beliefs. Domains key to changing radiographic guideline adherence, LBP imaging behaviours, and/or informing intervention design were identified by noting conflicting beliefs and their reported influence on the target behaviours. Results Six of the 14 TDF domains were perceived to be important for adherence to radiographic guidelines and managing non-specific LBP without imaging. Participating chiropractors reported varying levels of knowledge and awareness of guidelines for LBP imaging (Knowledge). Many chiropractors based their decision for imaging on clinical presentation, but some relied on “gut feeling” (Memory, attention, and decision processes). While chiropractors thought it was their role to manage LBP without imaging, others believed ordering imaging was the responsibility of other healthcare providers (Social/professional role and identity). Contrasting views were found regarding the negative consequences of imaging or not imaging LBP patients (Beliefs about consequences). Communication was identified as a skill required to manage LBP without imaging (Skills) and a strategy to enable appropriate imaging ordering behaviours (Behavioural regulation). Chiropractors suggested that access to patients’ previous imaging and a system that facilitated better interprofessional communication would likely improve their LBP imaging behaviours (Behavioural regulation). Conclusion We identified potential influences, in six theoretical domains, on participating chiropractors’ LBP imaging behaviours and adherence to radiographic guidelines. These beliefs may be targets for theory-informed behaviour change interventions aimed at improving these target behaviours for chiropractors in NL

The Efficacy of Generating Three Independent Anti-HIV-1 siRNAs from a Single U6 RNA Pol III-Expressed Long Hairpin RNA

RNA Interference (RNAi) effectors have been used to inhibit rogue RNAs in mammalian cells. However, rapidly evolving sequences such as the human immunodeficiency virus type 1 (HIV-1) require multiple targeting approaches to prevent the emergence of escape variants. Expressed long hairpin RNAs (lhRNAs) have recently been used as a strategy to produce multiple short interfering RNAs (siRNAs) targeted to highly variant sequences. We aimed to characterize the ability of expressed lhRNAs to generate independent siRNAs that silence three non-contiguous HIV-1 sites by designing lhRNAs comprising different combinations of siRNA-encoding sequences. All lhRNAs were capable of silencing individual target sequences. However, silencing efficiency together with concentrations of individual lhRNA-derived siRNAs diminished from the stem base (first position) towards the loop side of the hairpin. Silencing efficacy against HIV-1 was primarily mediated by siRNA sequences located at the base of the stem. Improvements could be made to first and second position siRNAs by adjusting spacing arrangements at their junction, but silencing of third position siRNAs remained largely ineffective. Although lhRNAs offer advantages for combinatorial RNAi, we show that good silencing efficacy across the span of the lhRNA duplex is difficult to achieve with sequences that encode more than two adjacent independent siRNAs

HARPS3 for a roboticized Isaac Newton telescope

This is the author accepted manuscript. The final version is available from the publisher via the DOI in this record.We present a description of a new instrument development, HARPS3, planned to be installed on an upgraded and roboticized Isaac Newton Telescope by end-2018. HARPS3 will be a high resolution (R = 115,000) echelle spectrograph with a wavelength range from 380-690 nm. It is being built as part of the Terra Hunting Experiment - a future 10 year radial velocity measurement programme to discover Earth-like exoplanets. The instrument design is based on the successful HARPS spectrograph on the 3.6m ESO telescope and HARPS-N on the TNG telescope. The main changes to the design in HARPS3 will be: a customised fibre adapter at the Cassegrain focus providing a stabilised beam feed and on-sky fibre diameter ~ 1.4 arcsec, the implementation of a new continuous flow cryostat to keep the CCD temperature very stable, detailed characterisation of the HARPS3 CCD to map the effective pixel positions and thus provide an improved accuracy wavelength solution, an optimised integrated polarimeter and the instrument integrated into a robotic operation. The robotic operation will optimise our programme which requires our target stars to be measured on a nightly basis. We present an overview of the entire project, including a description of our anticipated robotic operation.R.H. acknowledges the Science and Technologies Facilities Council (STFC) for his PhD studentship award (2015).J.I.G.H. acknowledges financial support from the Spanish Ministry of Economy and Competitiveness (MINECO) under the 2013 Ram´on y Cajal program MINECO RYC-2013-14875.J.I.G.H., R.R., and S.S.T. also acknowledge the Spanish ministry project MINECO AYA2014-56359-P.NP and ES are grateful to Knut and Alice Wallenberg Foundation for a generous support of the Swedish contribution to the THE project.AD acknowledges the support from Russian Foundation for Basic Research as part of research grant 15-52-12371