3,795 research outputs found

    Simple universal models capture all classical spin physics

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    Spin models are used in many studies of complex systems---be it condensed matter physics, neural networks, or economics---as they exhibit rich macroscopic behaviour despite their microscopic simplicity. Here we prove that all the physics of every classical spin model is reproduced in the low-energy sector of certain `universal models'. This means that (i) the low energy spectrum of the universal model reproduces the entire spectrum of the original model to any desired precision, (ii) the corresponding spin configurations of the original model are also reproduced in the universal model, (iii) the partition function is approximated to any desired precision, and (iv) the overhead in terms of number of spins and interactions is at most polynomial. This holds for classical models with discrete or continuous degrees of freedom. We prove necessary and sufficient conditions for a spin model to be universal, and show that one of the simplest and most widely studied spin models, the 2D Ising model with fields, is universal.Comment: v1: 4 pages with 2 figures (main text) + 4 pages with 3 figures (supplementary info). v2: 12 pages with 3 figures (main text) + 35 pages with 6 figures (supplementary info) (all single column). v2 contains new results and major revisions (results for spin models with continuous degrees of freedom, explicit constructions, examples...). Close to published version. v3: minor typo correcte

    Postpositivist, critical realism: philosophy, methodology and method for nursing research

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    Background: Healthcare research acknowledges a range of paradigms, including postpositivism and critical realist methodologies. However, there are few examples of such studies, which may discourage nurses from considering it to be a viable option. Aims:To provide a detailed overview of Bhaskar’s critical realism and illustrate its methods with published examples Discussion: Bhaskar’s critical realist methodology is explained and three main research methods are illustrated: critical realist evaluation, action research and ethnography. Conclusion: Postpositivism negotiates some of the conflict and differences between positivism and interpretivism. It offers a variety of methodological choices for nurses who do not wish to align themselves only with facts, cause and effect, proving hypotheses, or the perspectives and experiences of participants. Implications for Practice: Researchers can use Bhaskar’s critical realist principles to study complex and open systems, such as those of teams and organisations, public health interventions, and social situations, but particularly the complexities of nursing practice, service delivery and service design

    Art rupestre a l’arc mediterrani de la península Ibèrica. Del Cogul a Kyoto

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    La Roca dels Moros del Cogul és el primer conjunt de pintures prehistòriques documentat a Catalunya i va ser des del moment del seu descobriment, l’any 1908, un referent de l’art prehistòric peninsular; la seva existència adquirí un ressò internacional equiparable a l’assolit pels bisons d’Altamira. La història de la Roca dels Moros del Cogul és la història de l’art rupestre prehistòric del vessant oriental de la península Ibèrica. A partir d’aquest conjunt, es fa una síntesi dels resultats de la investigació sobre l’art rupestre postpaleolític a l’arc mediterrani de la península Ibèrica durant més de cent anys, sense oblidar els esforços realitzats des de les administracions per avançar en la conservació i protecció d’aquest tipus de jaciments arqueològics, cosa que va fer possible la inclusió de l’art rupestre de l’arc mediterrani de la península Ibèrica a la llista del Patrimoni Mundial de la UNESCO

    Rock art of the Mediterranean basin on the Iberian Peninsula. From El Cogul to Kyoto

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    Roca dels Moros in El Cogul is the first set of prehistoric paintings documented in Catalonia, and since its discovery in 1908 it has been a referent in prehistoric art on the Iberian Peninsula. Its existence garnered international attention on par with the bison of Altamira. The history of Roca dels Moros in El Cogul is the history of prehistoric rock art on the eastern side of the Iberian Peninsula. Based on this site, this article is a synthesis of the results of a study on the post-Palaeolithic rock art of the Mediterranean basin on the Iberian Peninsula for over 100 years, along with a discussion of the public administrations’ efforts to further the conservation and protection of this kind of archaeological site. These efforts have earned the rock art of the Mediterranean basin on the Iberian Peninsula a place on UNESCO’s list of World Heritage Sites

    An open-source alignment method for multichannel infinite-conjugate microscopes using a ray transfer matrix analysis model

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    Multichannel, infinite-conjugate optical systems easily allow implementation of multiple image paths and imaging modes into a single microscope. Traditional optical alignment methods which rely on additional hardware are not always simple to implement, particularly in compact open-source microscope designs. We present here an alignment algorithm and process to position the lenses and cameras in a microscope using only image magnification measurements. We show that the resulting positioning accuracy is comparable to the axial resolution of the microscope. Ray transfer matrix analysis is used to model the imaging paths when the optics are both correctly and incorrectly aligned. This is used to derive the corresponding image magnifications. We can then extract information about the lens positions using simple image-based measurements to determine whether there is misalignment of the objective lens to sample distance (working distance) and with what magnitude and direction the objective lens needs to be adjusted. Using the M4All open-source 3D printable microscope system in combination with the OpenFlexure microscope, we validate the alignment method and highlight its usability. We provide the model and an example implementation of the algorithm as an open-source Jupyter Notebook

    Exploring the Link Between Self-Construal and Distress Among African American and Asian American College Students

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    The authors investigated ethnicity, self-construal, and distress among African American and Asian American college students. African American students expressed more salient independent self-construals, whereas Asian American students expressed more salient interdependent self-construals. As hypothesized, among African American participants, distress was positively related to interdependent self-construal and negatively associated with independent self-construal. Contrary to prediction, the same pattern was found for Asian American participants. Multicultural clinical practice implications are presented

    Using Pre-Lecture Activities to Enhance Learner Engagement in a Large Group Setting

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    The disadvantage to students of beginning a module with no prior knowledge or inaccurate knowledge is well documented. For learners, the development of the necessary prior knowledge to facilitate their learning is essential. The use of screencasts, whether prior to or during class, is becoming more widespread. There is a need, however, to better understand how these are used and whether or not there is any impact on overall learner engagement and academic achievement when a component with instantaneous feedback (such as a multiple choice quiz) is embedded into the pre-lecture screencast activity. In this study, pre-learning activities consisting of screencasts and multiple choice quizzes were introduced to improve student engagement with the topic, gauge common misconceptions and give timely feedback to the students. An examination of screencast usage indicated that students did not predominantly nor exclusively employ the resources as originally intended, that is, in advance of lectures. Rather, students continued to access the activities across the module and often after the associated lecture. Implications are discussed with an acknowledgement of the importance of taking into account how learners prefer to use resources when designing and introducing new activities to modules. Keywords large group teaching, learner engagement, multiple choice quizzes, prior knowledge, screencasts Identifying and enhancing learner prior knowledge – what do learners know already and how can this help them?[AQ1] To find ways to support student learning, educators are increasingly turning their attention to the very roots of the learning experience, that is, to the knowledge, skills, environments and processes already possessed and encountered by the learner before the new, to-be-learned material is introduced (Coppola and Krajcik, 2014). Although such awareness of the importance of prior knowledge is not a recent emergence (Ausubel, 1968), interest in what learners know in advance
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