Anomalous strong exchange narrowing in excitonic systems

We investigate theoretically the phenomenon of exchange narrowing in the absorption spectrum of a chain of monomers, which are coupled via resonant dipole-dipole interaction. The individual (uncoupled) monomers exhibit a broad absorption line shape due to the coupling to an environment consisting of a continuum of vibrational modes. Upon increasing the interaction between the monomers, the absorption spectrum of the chain narrows. For a non-Markovian environment with a Lorentzian spectral density, we find a narrowing of the peak width (full width at half maximum (FWHM)) by a factor 1/N, where N is the number of monomers. This is much stronger than the usual 1/sqrt{N} narrowing. Furthermore it turns out that for a Markovian environment no exchange narrowing at all occurs. The relation of different measures of the width (FWHM, standard deviation) is discussed

Exploring evidence-based practice by occupational therapists when working with people with apraxia

Short Report Evidence in the literature supports a number of interventions that occupational therapists may utilise when working with people with apraxia, although there is no gold standard approach. A large-scale survey (n = 304, 36% response rate) was conducted with the membership of the College of Occupational Therapists Specialist Section – Neurological Practice to explore therapists’ understanding of apraxia and to provide a benchmark of current practice. Consensus was found in the majority of belief statements regarding the condition, although the respondents were unclear about the relationship between cognition and apraxia. When the therapists were asked to indicate their choice and use of interventions for apraxia, the results showed that the main consideration was the context in which a person performs activities, with moderate use of specific techniques including errorless learning and chaining. The results are related to the evidence base and the implications for occupational therapy practice and education are discussed

Evaluating model accuracy for model-based reasoning

Described here is an approach to automatically assessing the accuracy of various components of a model. In this approach, actual data from the operation of a target system is used to drive statistical measures to evaluate the prediction accuracy of various portions of the model. We describe how these statistical measures of model accuracy can be used in model-based reasoning for monitoring and design. We then describe the application of these techniques to the monitoring and design of the water recovery system of the Environmental Control and Life Support System (ECLSS) of Space Station Freedom

Comparative experiences of two teacher educators: a self-study

This paper focuses on the reflections of a less experienced and a veteran teacher educator at a new university and compares and contrasts their experiences of primary teacher education. The paper draws on the power of the narrative to share these experiences through aspects of self-study. Autobiographical research methods were used to elicit reflection on significant events in the teacher educators’ different and individual pasts in order to understand more about effective learning and teaching in their present roles. This process led to an examination of the values that underpinned and continue to underpin practice. The collaborative examination of significant aspects of personal practice has led to renewed confidence and implications for primary teacher education within the University. Key Words Self-study; narrative; teacher-educator; stories; values; reflection

A probability current analysis of energy transport in open quantum systems

We introduce a probability current analysis of excitation energy transfer between states of an open quantum system. Expressing the energy transfer through currents of excitation probability between the states in a site representation enables us to gain key insights into the energy transfer dynamics. It allows to, i) identify the pathways of energy transport in large networks of sites and to quantify their relative weights, ii) quantify the respective contributions of unitary dynamics, dephasing, and relaxation/dissipation processes to the energy transfer, and iii) quantify the contribution of coherence to the energy transfer. Our analysis is general and can be applied to a broad range of open quantum system descriptions (with coupling to non-Markovian environments) in a straightforward manner

Continuous Measurement of a Non-Markovian Open Quantum System

Continuous quantum measurement is the backbone of various methods in quantum control, quantum metrology, and quantum information. Here, we present a generalized formulation of dispersive measurement of a complex quantum systems. We describe the complex system as an open quantum system that is strongly coupled to a non-Markovian environment, enabling the treatment of a broad variety of natural or engineered complex systems. The system is monitored via a probe resonator coupled to a broadband (Markovian) reservoir. Based on this model, we derive a formalism of Stochastic Hierarchy Equations of Motion (SHEM) describing the decoherence dynamics of the system conditioned on the measurement record. Furthermore, we demonstrate a spectroscopy method based on weak quantum measurement to reveal the non-Markovian nature of the environment, which we term weak spectroscopy.Comment: Published version, the section on continuous state tomography will be published in a separate manuscrip

The effectiveness of origami on overall hand function after injury: A pilot controlled trial

This pilot study measured the effectiveness of using origami to improve the overall hand function of outpatients attending an NHS hand injury unit. The initiative came from one of the authors who had used origami informally in the clinical setting and observed beneficial effects. These observed effects were tested experimentally. The design was a pilot non-randomised controlled trial with 13 participants. Allocation of the seven control group members was based on patient preference. The experimental group members attended a weekly hour of origami for six weeks, in addition to their conventional rehabilitation. Hand function of all participants was measured using the Jebsen-Taylor Hand Function Test before and after the six-week period, and additional qualitative data were gathered in the form of written evaluations from patients. The quantitative data were analysed using the Mann Whitney U test or Fisher’s exact test. Themes were highlighted from the qualitative data. The results show that there was a greater difference in the total score of the experimental group using the impaired hand between pre- and post-intervention of 11.8 seconds, compared with 4.3 seconds in the control group, but this was not statistically significant at the 5% level (p=0.06). Additionally, differences in the sub-test scores show a markedly larger improvement in the experimental group. Qualitative data indicate that the experimental group experienced the origami sessions as being enjoyable and beneficial. Further research with a larger sample and randomised group allocation is recommended to verify and expand these preliminary findings

Cultural Diversity in the United States and Its Impact on Human Development

Previous studies have yielded mixed results on the impact of cultural diversity on economic performance. We find a positive relationship in the United States between cultural diversity and a comprehensive measure of human development that incorporates health, education, and income. We also disaggregate cultural diversity into three components including ethnicity, language, and religion. We find a positive relationship between human development and both religious and language diversity, and a negative relationship with ethnic diversity. These relationships are robust, using several alternative mathematical measures of diversity. Our results are consistent with diversity generating benefits from exposure to a variety of experiences, ideas, and skills while introducing costs due to difficulty in communication, difference in preferences, and conflict between polarized groups. We conclude that strong institutions are essential to maximize the benefits of diversity while mitigating the associated costs

A study of thin metallic films prepared at low temperatures

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Vibronic Lineshapes of PTCDA Oligomers in Helium Nanodroplets

Oligomers of the organic semiconductor PTCDA are studied by means of helium nanodroplet isolation (HENDI) spectroscopy. In contrast to the monomer absorption spectrum, which exhibits clearly separated, very sharp absorption lines, it is found that the oligomer spectrum consists of three main peaks having an apparent width orders of magnitude larger than the width of the monomer lines. Using a simple theoretical model for the oligomer, in which a Frenkel exciton couples to internal vibrational modes of the monomers, these experimental findings are nicely reproduced. The three peaks present in the oligomer spectrum can already be obtained taking only one effective vibrational mode of the PTCDA molecule into account. The inclusion of more vibrational modes leads to quasi continuous spectra, resembling the broad oligomer spectra