4,702 research outputs found
The Universe is not a Computer
When we want to predict the future, we compute it from what we know about the
present. Specifically, we take a mathematical representation of observed
reality, plug it into some dynamical equations, and then map the time-evolved
result back to real-world predictions. But while this computational process can
tell us what we want to know, we have taken this procedure too literally,
implicitly assuming that the universe must compute itself in the same manner.
Physical theories that do not follow this computational framework are deemed
illogical, right from the start. But this anthropocentric assumption has
steered our physical models into an impossible corner, primarily because of
quantum phenomena. Meanwhile, we have not been exploring other models in which
the universe is not so limited. In fact, some of these alternate models already
have a well-established importance, but are thought to be mathematical tricks
without physical significance. This essay argues that only by dropping our
assumption that the universe is a computer can we fully develop such models,
explain quantum phenomena, and understand the workings of our universe. (This
essay was awarded third prize in the 2012 FQXi essay contest; a new afterword
compares and contrasts this essay with Robert Spekkens' first prize entry.)Comment: 10 pages with new afterword; matches published versio
Cyclotron waves in a collisionless plasma
Plasma waves with resonances near electron cyclotron frequency investigated in long collisionless plasma column - wavelength dispersion curves and relation
Experimental investigation of the fundamental modes of a collisionless plasma quarterly report no. 3, sep. 11 - dec. 10, 1964
Plasma waves between electron cyclotron frequency and upper hybrid frequency in collisionless hydrogen plasm
Disentangling the quantum world
Correlations related to quantum entanglement have convinced many physicists that there must be some at-a-distance connection between separated events, at the quantum level. In the late 1940s, however, O. Costa de Beauregard proposed that such correlations can be explained without action at a distance, so long as the influence takes a zigzag path, via the intersecting past lightcones of the events in question. Costa de Beauregard's proposal is related to what has come to be called the retrocausal loophole in Bell's Theorem, but-like that loophole-it receives little attention, and remains poorly understood. Here we propose a new way to explain and motivate the idea. We exploit some simple symmetries to show how Costa de Beauregard's zigzag needs to work, to explain the correlations at the core of Bell's Theorem. As a bonus, the explanation shows how entanglement might be a much simpler matter than the orthodox view assumes-not a puzzling feature of quantum reality itself, but an entirely unpuzzling feature of our knowledge of reality, once zigzags are in play. © 2015 by the authors
Phenomenological model for predicting the energy resolution of neutron-damaged coaxial HPGe detectors
The peak energy resolution of germanium detectors deteriorates with
increasing neutron fluence. This is due to hole capture at neutron-created
defects in the crystal which prevents the full energy of the gamma-ray from
being recorded by the detector. A phenomenological model of coaxial HPGe
detectors is developed that relies on a single, dimensionless parameter that is
related to the probability for immediate trapping of a mobile hole in the
damaged crystal. As this trap parameter is independent of detector dimensions
and type, the model is useful for predicting energy resolution as a function of
neutron fluence.Comment: 7 pages, 7 figure
Endothelium-derived microparticles from chronically thromboembolic pulmonary hypertensive patients facilitate endothelial angiogenesis.
11 p.-4 fig.-1 tab.Background: Increased circulating levels of endoglin+ endothelial microparticles (EMPs) have been identified in several cardiovascular disorders, related to severity. Endoglin is an auxilary receptor for transforming growth factor β (TGF-β) important in the regulation of vascular structure.Results: We quantified the number of microparticles in plasma of six patients with chronic thromboembolic pulmonary hypertension (CTEPH) and age- and sex-matched pulmonary embolic (PE) and healthy controls and investigated the role of microparticle endoglin in the regulation of pulmonary endothelial function in vitro. Results show significantly increased levels of endoglin+ EMPs in CTEPH plasma, compared to healthy and disease controls. Co-culture of human pulmonary endothelial cells with CTEPH microparticles increased intracellular levels of endoglin and enhanced
TGF-β-induced angiogenesis and Smad1,5,8 phosphorylation in cells, without affecting BMPRII expression. In an in vitro model, we generated endothelium-derived MPs with enforced membrane localization of endoglin. Co-culture of these MPs with endothelial cells increased cellular endoglin content, improved cell survival and stimulated
angiogenesis in a manner similar to the effects induced by overexpressed protein.Conclusions: Increased generation of endoglin+ EMPs in CTEPH is likely to represent a protective mechanism supporting endothelial cell survival and angiogenesis, set to counteract the effects of vascular occlusion and endothelial damage.This research was supported by a project grant (PG 11/13/28765) from the British Heart Foundation and by grants from Ministerio de Economia y Competitividad of Spain (SAF2013-43421-R to CB)Peer reviewe
Increases in salience of ethnic identity at work: the roles of ethnic assignation and ethnic identification
To better understand how ethnicity is actually experienced within organisations, we examined reported increases in ethnic identity salience at work and responses to such increases. Thirty British black Caribbean graduate employees were interviewed about how and when they experienced their ethnic identity at work. The findings demonstrated that increased salience in ethnic identity was experienced in two key ways: through ‘ethnic assignation’ (a ‘push’ towards ethnic identity) and ‘ethnic identification’ (a ‘pull’ towards ethnic identity). We explore how and when ethnic assignation and ethnic identification occur at work, and their relevance to how workplaces are experienced by this group of minority ethnic employees. The findings suggest the need for further research attention to the dynamic and episodic nature of social identity, including ethnic identity, within organisations, and to the impact of such increases in salience of social identities on behaviour at work
Windows of Heaven: Hymns New and Old for the Church, Sunday School and Home
Windows of Heaven, by Henry Marvin Wharton and I. S. Fields, published by the Wharton & Barron Publishing Company.
Hymn Titles from text include: Bethany ( Nearer, My God To Thee ); I Gave My Life For Thee; Work For The Night; Missionary Hymn; What A Friend; The Solid Rock; Boylston ( Did Christ o\u27er sinners weep? ); Brown, C.M. ( Am I a soldier of the cross... ) Lenox ( Arise, my soul, arise... ); Coronation ( All hail the power of Jesus\u27 name! ); Heber, C.M. ( Come, humble sinner, in whose breast... ); Azmon, C.M. ( O for a closer walk with God... )https://digitalcommons.gardner-webb.edu/round-note-collection/1001/thumbnail.jp
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