Antiphase dynamics in a multimode semiconductor laser with optical injection

A detailed experimental study of antiphase dynamics in a two-mode semiconductor laser with optical injection is presented. The device is a specially designed Fabry-Perot laser that supports two primary modes with a THz frequency spacing. Injection in one of the primary modes of the device leads to a rich variety of single and two-mode dynamical scenarios, which are reproduced with remarkable accuracy by a four dimensional rate equation model. Numerical bifurcation analysis reveals the importance of torus bifurcations in mediating transitions to antiphase dynamics and of saddle-node of limit cycle bifurcations in switching of the dynamics between single and two-mode regimes.Comment: 7 pages, 9 figure

Characterization and Evaluation of Methane Oxidation Catalysts for Dual-Fuel Diesel and Natural Gas Engines

The UK has incentivized the use of natural gas in heavy goods vehicles (HGVs) by converting to dual-fuel (DF) diesel-natural gas systems to reduce noxious and greenhouse gas emissions. Laboratory and on-road measurements of DF vehicles have demonstrated a decrease in CO$_2$ emissions relative to diesel, but there is an increase in greenhouse gas (CO$_2$e) emissions because of unburned methane. Decreasing tailpipe emissions of methane via after-treatment devices in lean-burn compression ignition engines is a challenge because of low exhaust temperatures (~400 °C) and the presence of water vapor. In this study, six commercially available methane oxidation catalysts (MOCs) were tested for their application in DF HGV vehicles. Each MOC was characterized in terms of the catalyst platinum group metal (PGM) loading (both Pd and Pt), particle size, catalytic surface area, and Pd:Pt ratio. In addition, the washcoat surface area, pore volume, and pore size were evaluated. The MOC conversion efficiency was evaluated in controlled methane-oxidation experiments with varying temperatures, flow rates, and gas compositions. Characteristic-conversion efficiency correlations demonstrate that the influential MOC characteristics were PGM loading (both Pd and Pt), Pd:Pt ratio, washcoat surface area, and washcoat pore volume. With 90 % methane oxidation at less than 400 °C in DF HGV exhaust conditions, sample 1 had the highest conversion efficiency because of a high PGM loading (330 g/ft$^3$, 12,000 g/m$^3$), a 5.9 Pd:Pt ratio, a high alumina washcoat surface area of 20 m$^2$/cm$^3$, and 74-mm$^3$/cm$^3$ pore volume. Additional studies showed increased MOC conversion efficiency with decreasing gas hourly space velocities (GHSVs) and increasing methane concentrations.We acknowledge support from the UK Engineering and Physical Sciences Research Council (EP/K00915X/1), the UK Department for Transport, the Office for Low Emission Vehicles and Innovate UK (project reference 400266), and the industrial partners of the Centre for Sustainable Road Freight. GreenUrban Technologies Ltd. (3) and Prins Autogas UK Ltd. (1) provided the samples for testing in this study

Optimisation of a Multi-Gravity Separator with Novel Modifications for the Recovery of Ferberite

This is the final version of the article. Available from MDPI via the DOI in this record.Tungsten is considered by the European Union as a critical raw material for future development due to its expected demand and scarcity of resource within Europe. It is therefore, critical to optimize European tungsten operations and maximise recoveries. The role of enhanced gravity/centrifugal concentrators in recovering tungsten from ultra-fine fractions should form an important part of this aim. Reported herein are the results of investigations to improve efficiency of Wolf Minerals’ Draklends mine, a major European tungsten mine, by recovering saleable material from a magnetic waste stream of a low-intensity magnetic separator using an enhanced gravity concentrator. The mine hosts wolframite and ferberite as the main tungsten bearing mineral species. A Mozley multi-gravity separator (MGS) C-900 was selected as it is suited to exploiting small variations in mineral density to affect a separation. Working with a current manufacturer, a novel scraping blade system was tested. To assess the MGS in a statistically valid manner, a response surface methodology was followed to determine optimal test conditions. The test programme showed that the most important parameters were drum speed and wash water rate. Under optimal conditions the model predicted that 40% of the tungsten could be recovered above the required grade of 43% WO3.This work is part of the OptimOre project. This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No. 642201. Authors are thankful to Wolf Minerals for providing material for experimentation and to Gravity Mining Ltd. for support in undertaking experiments and providing the opportunity to test the modified low profile blades

Dynamics of a semiconductor laser with optical feedback

We investigate both experimentally and theoretically the dynamics of a semiconductor laser with optical feedback in the low-frequency fluctuation regime. First we demonstrate that low-frequency fluctuations can be observed for both single and multimode operation of a semiconductor laser with optical feedback. The analysis of the fast dynamics associated with this low-frequency instability is well described by single-mode rate equations. In the multimode regime, fast pulsation is observed in every laser mode. In this case the fluctuations in total intensity are much smaller than those in the intensity of each individual mode, This indicates the presence of anticorrelations dynamics at high frequency between the different laser modes. (S1050-2947(99)08307-9)

Maternal and child health nurse screening and care for mothers experiencing domestic violence (MOVE): A cluster randomised trial

BACKGROUND: Mothers are at risk of domestic violence (DV) and its harmful consequences postpartum. There is no evidence to date for sustainability of DV screening in primary care settings. We aimed to test whether a theory-informed, maternal and child health (MCH) nurse-designed model increased and sustained DV screening, disclosure, safety planning and referrals compared with usual care. METHODS: Cluster randomised controlled trial of 12 month MCH DV screening and care intervention with 24 month follow-up. The study was set in community-based MCH nurse teams (91 centres, 163 nurses) in north-west Melbourne, Australia. Eight eligible teams were recruited. Team randomisation occurred at a public meeting using opaque envelopes. Teams were unable to be blinded. The intervention was informed by Normalisation Process Theory, the nurse-designed good practice model incorporated nurse mentors, strengthened relationships with DV services, nurse safety, a self-completion maternal health screening checklist at three or four month consultations and DV clinical guidelines. Usual care involved government mandated face-to-face DV screening at four weeks postpartum and follow-up as required. Primary outcomes were MCH team screening, disclosure, safety planning and referral rates from routine government data and a postal survey sent to 10,472 women with babies ≤ 12 months in study areas. Secondary outcomes included DV prevalence (Composite Abuse Scale, CAS) and harm measures (postal survey). RESULTS: No significant differences were found in routine screening at four months (IG 2,330/6,381 consultations (36.5 %) versus CG 1,792/7,638 consultations (23.5 %), RR = 1.56 CI 0.96-2.52) but data from maternal health checklists (n = 2,771) at three month IG consultations showed average screening rates of 63.1 %. Two years post-intervention, IG safety planning rates had increased from three (RR 2.95, CI 1.11-7.82) to four times those of CG (RR 4.22 CI 1.64-10.9). Referrals remained low in both intervention groups (IGs) and comparison groups (CGs) (<1 %). 2,621/10,472 mothers (25 %) returned surveys. No difference was found between arms in preference or comfort with being asked about DV or feelings about self. CONCLUSION: A nurse-designed screening and care model did not increase routine screening or referrals, but achieved significantly increased safety planning over 36 months among postpartum women. Self-completion DV screening was welcomed by nurses and women and contributed to sustainability. TRIAL REGISTRATION: Australian New Zealand Clinical Trials Registry, ACTRN12609000424202, 10/03/2009

Time resolved pattern evolution in a large aperture laser

We have measured quasi-instantaneous transverse patterns in a broad aperture laser. Non-ordered patterns yielding to boundary determined regular structures in progressive time-integrated recording are observed. The linear analysis and numerical integration of the full Maxwell-Bloch equations allow us to interpret the features of the experiment. We show that this system being far from threshold cannot be fully understood with a perturbative model.Comment: 7 pages, 5 GIF figures . To be published in Phys. Rev. Let

On finite pp-groups whose automorphisms are all central

An automorphism $\alpha$ of a group $G$ is said to be central if $\alpha$ commutes with every inner automorphism of $G$. We construct a family of non-special finite $p$-groups having abelian automorphism groups. These groups provide counter examples to a conjecture of A. Mahalanobis [Israel J. Math., {\bf 165} (2008), 161 - 187]. We also construct a family of finite $p$-groups having non-abelian automorphism groups and all automorphisms central. This solves a problem of I. Malinowska [Advances in group theory, Aracne Editrice, Rome 2002, 111-127].Comment: 11 pages, Counter examples to a conjecture from [Israel J. Math., {\bf 165} (2008), 161 - 187]; This paper will appear in Israel J. Math. in 201

Diagnostic change 10 years after a first episode of psychosis

Background. A lack of an aetiologically based nosology classification has contributed to instability in psychiatric diag-noses over time. This study aimed to examine the diagnostic stability of psychosis diagnoses using data from an inci-dence sample of psychosis cases, followed up after 10 years and to examine those baseline variables which were associated with diagnostic change. Method. Data were examined from the ÆSOP and ÆSOP-10 studies, an incidence and follow-up study, respectively, of a population-based cohort of first-episode psychosis cases from two sites. Diagnosis was assigned using ICD-10 and DSM-IV-TR. Diagnostic change was examined using prospective and retrospective consistency. Baseline variables asso-ciated with change were examined using logistic regression and likelihood ratio tests. Results. Slightly more (59.6%) cases had the same baseline and lifetime ICD-10 diagnosis compared with DSM-IV-TR (55.3%), but prospective and retrospective consistency was similar. Schizophrenia, psychotic bipolar disorder and drug-induced psychosis were more prospectively consistent than other diagnoses. A substantial number of cases with other diagnoses at baseline (ICD-10, n = 61; DSM-IV-TR, n = 76) were classified as having schizophrenia at 10 years

A universal equation to predict methane production of forage-fed cattle in Australia

The methods for estimating methane emissions from cattle as used in the Australian national inventory are based on older data that have now been superseded by a large amount of more recent data. Recent data suggested that the current inventory emissions estimates can be improved. To address this issue, a total of 1034 individual animal records of daily methane production (MP) was used to reassess the relationship between MP and each of dry matter intake (DMI) and gross energy intake (GEI). Data were restricted to trials conducted in the past 10 years using open-circuit respiration chambers, with cattle fed forage-based diets (forage >70%). Results from diets considered to inhibit methanogenesis were omitted from the dataset. Records were obtained from dairy cattle fed temperate forages (220 records), beef cattle fed temperate forages (680 records) and beef cattle fed tropical forages (133 records). Relationships were very similar for all three production categories and single relationships for MP on a DMI or GEI basis were proposed for national inventory purposes. These relationships were MP (g/day) = 20.7 (±0.28) × DMI (kg/day) (R2 = 0.92, P < 0.001) and MP (MJ/day) = 0.063 (±0.008) × GEI (MJ/day) (R2 = 0.93, P < 0.001). If the revised MP (g/day) approach is used to calculate Australia’s national inventory, it will reduce estimates of emissions of forage-fed cattle by 24%. Assuming a global warming potential of 25 for methane, this represents a 12.6 Mt CO2-e reduction in calculated annual emissions from Australian cattle