308 research outputs found

    What LFA beef and sheep farmers should do and why they should do it

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    This paper describes how representative farm business models were employed to identify optimal beef and sheep production systems for Less Favoured Area (LFA) farms in Northern Ireland. The bio-economic models identify the optimal farming system for theses farms under various market and policy assumptions. They are useful, therefore, in helping to develop industry strategy. The models indicate that, under current market and policy conditions, a dairy-based beef system is likely to be the most profitable beef enterprise. However, depending on land quality and livestock housing resources, and the market and policy environment, suckler-based beef systems can also feature in the profit maximising enterprise mix. The results also suggest that the optimal sheep system is consistent with the stratified sheep systems traditionally operated in Northern Ireland. In general, beef production appears to have some advantages over sheep production where, depending on relative prices and resource availabilities, it is often better to replace sheep with cattle and employ the released labour off-farm, than to replace cattle with sheep and invest the released capital off-farm. In some situations, farmers should significantly reduce their capital and labour inputs to the farm business by substantially reducing stocking rates or even abandoning land completelyAgricultural and Food Policy,

    Progress and opportunities in lesbian, gay, bisexual and transgender health communications

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    This article describes elements of effective health communication and highlights strategies that may best be adopted or adapted in relation to lesbian, gay, bisexual, and transgender (LGBT) populations. Studies have documented the utility of multidimensional approaches to health communication from the macro level of interventions targeting entire populations to the micro level of communication between health care provider and consumer. Although evidence of health disparities in LGBT communities underscores the importance of population-specific interventions, health promotion campaigns rarely target these populations and health communication activities seldom account for the diversity of LGBT communities. Advances in health communication suggest promising direction for LGBT-specific risk prevention and health promotion strategies on community, group, and provider/consumer levels. Opportunities for future health communication efforts include involving LGBT communities in the development of appropriate health communication campaigns and materials, enhancing media literacy among LGBT individuals, supporting LGBT-focused research and evaluation of health communication activities, and ensuring that health care providers possess the knowledge, skills, and competency to communicate effectively with LGBT consumers

    Time-resolved investigation of magnetization dynamics of arrays of non-ellipsoidal nanomagnets with a non-uniform ground state

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    We have performed time-resolved scanning Kerr microscopy (TRSKM) measurements upon arrays of square ferromagnetic nano-elements of different size and for a range of bias fields. The experimental results were compared to micromagnetic simulations of model arrays in order to understand the non-uniform precessional dynamics within the elements. In the experimental spectra two branches of excited modes were observed to co-exist above a particular bias field. Below the so-called crossover field, the higher frequency branch was observed to vanish. Micromagnetic simulations and Fourier imaging revealed that modes from the higher frequency branch had large amplitude at the center of the element where the effective field was parallel to the bias field and the static magnetization. Modes from the lower frequency branch had large amplitude near the edges of the element perpendicular to the bias field. The simulations revealed significant canting of the static magnetization and the effective field away from the direction of the bias field in the edge regions. For the smallest element sizes and/or at low bias field values the effective field was found to become anti-parallel to the static magnetization. The simulations revealed that the majority of the modes were de-localized with finite amplitude throughout the element, while the spatial character of a mode was found to be correlated with the spatial variation of the total effective field and the static magnetization state. The simulations also revealed that the frequencies of the edge modes are strongly affected by the spatial distribution of the static magnetization state both within an element and within its nearest neighbors

    Super-harmonic injection locking of nano-contact spin-torque vortex oscillators

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    Super-harmonic injection locking of single nano-contact (NC) spin-torque vortex oscillators (STVOs) subject to a small microwave current has been explored. Frequency locking was observed up to the fourth harmonic of the STVO fundamental frequency f0f_{0} in microwave magneto-electronic measurements. The large frequency tunability of the STVO with respect to f0f_{0} allowed the device to be locked to multiple sub-harmonics of the microwave frequency fRFf_{RF}, or to the same sub-harmonic over a wide range of fRFf_{RF} by tuning the DC current. In general, analysis of the locking range, linewidth, and amplitude showed that the locking efficiency decreased as the harmonic number increased, as expected for harmonic synchronization of a non-linear oscillator. Time-resolved scanning Kerr microscopy (TRSKM) revealed significant differences in the spatial character of the magnetization dynamics of states locked to the fundamental and harmonic frequencies, suggesting significant differences in the core trajectories within the same device. Super-harmonic injection locking of a NC-STVO may open up possibilities for devices such as nanoscale frequency dividers, while differences in the core trajectory may allow mutual synchronisation to be achieved in multi-oscillator networks by tuning the spatial character of the dynamics within shared magnetic layers.Comment: 21 pages, 8 figure

    Direct observation of magnetization dynamics generated by nano-contact spin-torque vortex oscillators

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    Time-resolved scanning Kerr microscopy has been used to directly image the magnetization dynamics of nano-contact (NC) spin-torque vortex oscillators (STVOs) when phase-locked to an injected microwave (RF) current. The Kerr images reveal free layer magnetization dynamics that extend outside the NC footprint, where they cannot be detected electrically, but which are crucial to phase-lock STVOs that share common magnetic layers. For a single NC, dynamics were observed not only when the STVO frequency was fully locked to that of the RF current, but also for a partially locked state characterized by periodic changes in the core trajectory at the RF frequency. For a pair of NCs, images reveal the spatial character of dynamics that electrical measurements show to have enhanced amplitude and reduced linewidth. Insight gained from these images may improve understanding of the conditions required for mutual phase-locking of multiple STVOs, and hence enhanced microwave power emission.Comment: 10 pages, 3 figure

    A behaviour sequence analysis of goal generation processes in a psychosis rehabilitation sample

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    Background: It is suggested that goals are hierarchically organised, with goals at the highest level representing fundamental values and motivations. These abstract goals are said to have a series of sub-goals which represent a means of reaching higher-level goals. While a number of studies have explored goals in the context of psychosis, little is known about idiographic goal generation processes in those experiencing psychosis. Methods: Using a Behaviour Sequence Analysis approach, the aim of the current study was to assess the feasibility of the goal task for use with individuals experiencing psychosis. A total of 73 adults receiving care from UK rehabilitation services completed a goal task designed to elicit higher-level goals. Results: Results indicated that the goal task may be a feasible tool to support those experiencing psychosis to generate lower- and higher-level goals. Conclusions: The goal task utilised in the current study may therefore be a valuable goal generation tool for use by clinicians

    Time-resolved imaging of magnetization dynamics in double nanocontact spin torque vortex oscillator devices

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    This is the published version. Available from the American Physical Society via the DOI in this recordDouble nanocontact (NC) spin transfer vortex oscillator devices, in which NCs of 100-nm diameter have center-to-center separation ranging from 200 to 1100 nm, have been studied by means of electrical measurements and time-resolved scanning Kerr microscopy (TRSKM). The NCs were positioned close to the edge of the top electrical contact so that the magnetization dynamics of the adjacent region could be probed optically. The electrical measurements showed different ranges of frequency operation for devices with different NC separations. For 900-nm NC separation, TRSKM showed magnetic contrast consistent with the formation of a magnetic vortex at each NC, while for 200-nm NC separation a lack of magnetic contrast near the NC region suggests that the magnetization dynamics occur closer to the NC and underneath the top contact. TRSKM also reveals the presence of additional localized dynamical features far from the NCs, which are not seen by electrical measurements; has not been reported previously for double NCs with different separations; and provides insight into how the dynamic state of the phase-locked oscillators is established and stabilized.Engineering and Physical Sciences Research Council (EPSRC)Ministry of Education, Chile and Commission for Scientific and Technological Research (CONICYT

    Behaviour Tracking: Using geospatial and behaviour sequence analysis to map crime

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    Crime is a complex phenomenon. To understand the commission of crime, researchers must map both the temporal and the spatial processes involved. The current research combines a temporal method of analysis, Behaviour Sequence Analysis, with geospatial mapping, to outline a new method of integrating temporal and spatial movements of criminals. To show how the new method can be applied, a burglary scenario was used, and the movements and behaviours of a criminal tracked around the property. Results showed that combining temporal and spatial analyses allows for a clearer account of the process of a crime scene. The current method has application to a large range of other crimes and terrorist movements, for instance between cities and movements within each city. Therefore, the current research provides the foundation framework for a novel method of spatio-temporal analyses of crime

    Imaging magnetisation dynamics in nano-contact spin-torque vortex oscillators exhibiting gyrotropic mode splitting

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    This is the author accepted manuscript. The final version is available from IOP Publishing via the DOI in this record.Nano-contact spin-torque vortex oscillators (STVOs) are anticipated to find application as nanoscale sources of microwave emission in future technological applications. Presently the output power and phase stability of individual STVOs are not competitive with existing oscillator technologies. Synchronisation of multiple nano-contact STVOs via magnetisation dynamics has been proposed to enhance the microwave emission. The control of device-to-device variations, such as mode splitting of the microwave emission, is essential if multiple STVOs are to be successfully synchronised. In this work a combination of electrical measurements and time-resolved scanning Kerr microscopy (TRSKM) was used to demonstrate how mode splitting in the microwave emission of STVOs was related to the magnetisation dynamics that are generated. The free-running STVO response to a DC current only was used to identify devices and bias magnetic field configurations for which single and multiple modes of microwave emission were observed. Stroboscopic Kerr images were acquired by injecting a small amplitude RF current to phase lock the free-running STVO response. The images showed that the magnetisation dynamics of a multimode device with moderate splitting could be controlled by injecting an RF current so that they exhibit similar spatial character to that of a single mode. Significant splitting was found to result from a complicated equilibrium magnetic state that was observed in Kerr images as irregular spatial characteristics of the magnetisation dynamics. Such dynamics were observed far from the nano-contact and so their presence cannot be detected in electrical measurements. This work demonstrates that TRSKM is a powerful tool for the direct observation of the magnetisation dynamics generated by STVOs that exhibit complicated microwave emission. Characterisation of such dynamics outside the nano-contact perimeter permits a deeper insight into the requirements for optimal phase-locking of multiple STVOs that share common magnetic layers.The authors gratefully acknowledge the financial support of the Engineering and Physical Sciences Research Council under grants EP/I038470/1 and EP/K008501/1, the Royal Society under grant UF080837, the Swedish Research Council (VR), the Swedish Foundation for Strategic Research (SSF), and the Knut and Alice Wallenberg Foundation (KAW). The authors and co-authors declare that there are no conflicts of interes
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