222 research outputs found

    Optical control of 4f orbital state in rare-earth metals

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    Information technology demands continuous increase of data-storage density. In high-density magnetic recording media, the large magneto-crystalline anisotropy (MCA) stabilizes the stored information against decay through thermal fluctuations. In the latest generation storage media, MCA is so large that magnetic order needs to be transiently destroyed by heat to enable bit writing. Here we show an alternative approach to control high-anisotropy magnets: With ultrashort laser pulses the anisotropy itself can be manipulated via electronic state excitations. In rare-earth materials like terbium metal, magnetic moment and high MCA both originate from the 4f electronic state. Following infrared laser excitation 5d-4f electron-electron scattering processes lead to selective orbital excitations that change the 4f orbital occupation and significantly alter the MCA. Besides these excitations within the 4f multiplet, 5d-4f electron transfer causes a transient change of the 4f occupation number, which, too, strongly alters the MCA. Such MCA change cannot be achieved by heating: The material would rather be damaged than the 4f configuration modified. Our results show a way to overcome this limitation for a new type of efficient magnetic storage medium. Besides potential technological relevance, the observation of MCA-changing excitations also has implications for a general understanding of magnetic dynamics processes on ultrashort time scales, where the 4f electronic state affects the angular momentum transfer between spin system and lattice.Comment: Manuscript (14 pages, 3 figures) and Supplementary Information (22 pages, 9 figures

    A limited-size ensemble of homogeneous CNN/LSTMs for high-performance word classification

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    The strength of long short-term memory neural networks (LSTMs) that have been applied is more located in handling sequences of variable length than in handling geometric variability of the image patterns. In this paper, an end-to-end convolutional LSTM neural network is used to handle both geometric variation and sequence variability. The best results for LSTMs are often based on large-scale training of an ensemble of network instances. We show that high performances can be reached on a common benchmark set by using proper data augmentation for just five such networks using a proper coding scheme and a proper voting scheme. The networks have similar architectures (convolutional neural network (CNN): five layers, bidirectional LSTM (BiLSTM): three layers followed by a connectionist temporal classification (CTC) processing step). The approach assumes differently scaled input images and different feature map sizes. Three datasets are used: the standard benchmark RIMES dataset (French); a historical handwritten dataset KdK (Dutch); the standard benchmark George Washington (GW) dataset (English). Final performance obtained for the word-recognition test of RIMES was 96.6%, a clear improvement over other state-of-the-art approaches which did not use a pre-trained network. On the KdK and GW datasets, our approach also shows good results. The proposed approach is deployed in the Monk search engine for historical-handwriting collections

    Adenyl cyclases and cAMP in plant signaling - past and present

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    In lower eukaryotes and animals 3'-5'-cyclic adenosine monophosphate (cAMP) and adenyl cyclases (ACs), enzymes that catalyse the formation of cAMP from ATP, have long been established as key components and second messengers in many signaling pathways. In contrast, in plants, both the presence and biological role of cAMP have been a matter of ongoing debate and some controversy. Here we shall focus firstly on the discovery of cellular cAMP in plants and evidence for a role of this second messenger in plant signal transduction. Secondly, we shall review current evidence of plant ACs, analyse aspects of their domain organisations and the biological roles of candidate molecules. In addition, we shall assess different approaches based on search motifs consisting of functionally assigned amino acids in the catalytic centre of annotated and/or experimentally tested nucleotide cyclases that can contribute to the identification of novel candidate molecules with AC activity such as F-box and TIR proteins

    From research to practice: Lay adherence counsellors' fidelity to an evidence-based intervention for promoting adherence to antiretroviral treatment in the Western Cape, South Africa

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    In the Western Cape, lay counsellors are tasked with supporting antiretroviral (ARV) adherence in public healthcare clinics. Thirty-nine counsellors in 21 Cape Town clinics were trained in Options for Health (Options), an evidence-based intervention based on motivational interviewing (MI). We evaluated counsellors’ ability to deliver Options for addressing poor adherence following 5 days training. Audio-recordings of counselling sessions collected following training were transcribed and translated into English. Thirty-five transcripts of sessions conducted by 35 counsellors were analysed for fidelity to the Options protocol, and using the Motivational Interviewing Treatment and Integrity (MITI) code. Counsellors struggled with some of the strategies associated with MI, such as assessing readiness-to-change and facilitating change talk. Overall, counsellors failed to achieve proficiency in the approach of MI according to the MITI. Counsellors were able to negotiate realistic plans for addressing patients’ barriers to adherence. Further efforts aimed at strengthening the ARV adherence counselling programme are needed.Department of HE and Training approved lis

    Development and Evaluation of a Psychosocial Intervention for Children and Teenagers Experiencing Diabetes (DEPICTED): a protocol for a cluster randomised controlled trial of the effectiveness of a communication skills training programme for healthcare professionals working with young people with type 1 diabetes

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    Background Diabetes is the third most common chronic condition in childhood and poor glycaemic control leads to serious short-term and life-limiting long-term complications. In addition to optimal medical management, it is widely recognised that psychosocial and educational factors play a key role in improving outcomes for young people with diabetes. Recent systematic reviews of psycho-educational interventions recognise the need for new methods to be developed in consultation with key stakeholders including patients, their families and the multidisciplinary diabetes healthcare team. Methods/design Following a development phase involving key stakeholders, a psychosocial intervention for use by paediatric diabetes staff and not requiring input from trained psychologists has been developed, incorporating a communication skills training programme for health professionals and a shared agenda-setting tool. The effectiveness of the intervention will be evaluated in a cluster-randomised controlled trial (RCT). The primary outcome, to be measured in children aged 4-15 years diagnosed with type 1 diabetes for at least one year, is the effect on glycaemic control (HbA1c) during the year after training of the healthcare team is completed. Secondary outcomes include quality of life for patients and carers and cost-effectiveness. Patient and carer preferences for service delivery will also be assessed. Twenty-six paediatric diabetes teams are participating in the trial, recruiting a total of 700 patients for evaluation of outcome measures. Half the participating teams will be randomised to receive the intervention at the beginning of the trial and remaining centres offered the training package at the end of the one year trial period. Discussion The primary aim of the trial is to determine whether a communication skills training intervention for specialist paediatric diabetes teams will improve clinical and psychological outcomes for young people with type 1 diabetes. Previous research indicates the effectiveness of specialist psychological interventions in achieving sustained improvements in glycaemic control. This trial will evaluate an intervention which does not require the involvement of trained psychologists, maximising the potential feasibility of delivery in a wider NHS context. Trial registration Current Controlled Trials ISRCTN61568050

    The Time Course of the Influence of Valence and Arousal on the Implicit Processing of Affective Pictures

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    In the current study, we investigated the time course of the implicit processing of affective pictures with an orthogonal design of valence (negative vs. positive) by arousal (low vs. high). Previous studies with explicit tasks suggested that valence mainly modulates early event-related potential (ERP) components, whereas arousal mainly modulates late components. However, in this study with an implicit task, we observed significant interactions between valence and arousal at both early and late stages over both parietal and frontal sites, which were reflected by three different ERP components: P2a (100–200 ms), N2 (200–300 ms), and P3 (300–400 ms). Furthermore, there was also a significant main effect of arousal on P2b (200–300 ms) over parieto-occipital sites. Our results suggest that valence and arousal effects on implicit affective processing are more complicated than previous ERP studies with explicit tasks have revealed
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