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https://www.readbyqxmd.com/read/28430511/anti-de-sitter-particles-and-manifest-super-isometries
#1
Alex S Arvanitakis, Alec E Barns-Graham, Paul K Townsend
Starting from the classical action for a spin-zero particle in a D-dimensional anti-de Sitter (AdS) spacetime, we recover the Breitenlohner-Freedman bound by quantization. For D=4, 5, 7 and using an Sl(2;K) spinor notation for K=R,C,H, we find a bitwistor form of the action for which the AdS isometry group is linearly realized, although only for zero mass when D=4, 7 in agreement with previous constructions. For zero mass and D=4 the conformal isometry group is linearly realized. We extend these results to the superparticle in the maximally supersymmetric "AdS×S" string or M-theory vacua, showing that quantization yields a 128+128 component supermultiplet...
April 7, 2017: Physical Review Letters
https://www.readbyqxmd.com/read/28409957/background-independence-and-duality-invariance-in-string-theory
#2
Olaf Hohm
Closed string theory exhibits an O(D,D) duality symmetry on tori, which in double field theory is manifest before compactification. I prove that to first order in α^{'} there is no manifestly background independent and duality invariant formulation of bosonic string theory in terms of a metric, b field, and dilaton. To this end I use O(D,D) invariant second order perturbation theory around flat space to show that the unique background independent candidate expression for the gauge algebra at order α^{'} is inconsistent with the Jacobi identity...
March 31, 2017: Physical Review Letters
https://www.readbyqxmd.com/read/28409942/breakdown-of-string-perturbation-theory-for-many-external-particles
#3
Sudip Ghosh, Suvrat Raju
We consider massless string scattering amplitudes in a limit where the number of external particles becomes very large, while the energy of each particle remains small. Using the growth of the volume of the relevant moduli space, and by means of independent numerical evidence, we argue that string perturbation theory breaks down in this limit. We discuss some remarkable implications for the information paradox.
March 31, 2017: Physical Review Letters
https://www.readbyqxmd.com/read/28384482/decoding-levels-of-representation-in-reading-a%C3%A2-representational-similarity-approach
#4
Simon Fischer-Baum, Dorothy Bruggemann, Ivan Felipe Gallego, Donald S P Li, Emilio R Tamez
Multiple levels of representation are involved in reading single words: visual representations of letter shape, orthographic representations of letter identity and order, phonological representations of the word's pronunciation, and semantic representations of its meaning. Previous lesion and neuroimaging studies have identified a network of regions recruited during word reading, including ventral occipital-temporal regions and the angular gyrus (AG). However, there is still debate about what information is being represented and processed in these regions...
March 18, 2017: Cortex; a Journal Devoted to the Study of the Nervous System and Behavior
https://www.readbyqxmd.com/read/28376655/orthographic-processing-a-mid-level-vision-of-reading
#5
Jonathan Grainger
I will describe how orthographic processing acts as a central interface between visual and linguistic processing during reading, and as such can be considered to be the "mid-level vision" of reading research. In order to make this case, I first summarise the evidence in favour of letter-based word recognition before examining work investigating how orthographic similarities among words influence single word reading. I describe how evidence gradually accumulated against traditional measures of orthographic similarity and the associated theories of orthographic processing, forcing a reconsideration of how letter position information is represented by skilled readers...
April 5, 2017: Quarterly Journal of Experimental Psychology: QJEP
https://www.readbyqxmd.com/read/28339250/de-sitter-space-as-a-resonance
#6
Jonathan Maltz, Leonard Susskind
A quantum mechanical formulation of de Sitter cosmological spacetimes still eludes string theory. In this Letter we conjecture a potentially rigorous framework in which the status of de Sitter space is the same as that of a resonance in a scattering process. We conjecture that transition amplitudes between certain states with asymptotically supersymmetric flat vacua contain resonant pole characteristic metastable intermediate states. A calculation employing constrained instantons illustrates this idea.
March 10, 2017: Physical Review Letters
https://www.readbyqxmd.com/read/28339222/holographic-duals-for-five-dimensional-superconformal-quantum-field-theories
#7
Eric D'Hoker, Michael Gutperle, Christoph F Uhlemann
We construct global solutions to type IIB supergravity with 16 residual supersymmetries whose space-time is AdS_{6}×S^{2} warped over a Riemann surface. Families of solutions are labeled by an arbitrary number L≥3 of asymptotic regions, in each of which the supergravity fields match those of a (p,q) five-brane, and may therefore be viewed as near-horizon limits of fully localized intersections of five-branes in type IIB string theory. These solutions provide compelling candidates for holographic duals to a large class of five-dimensional superconformal quantum field theories which arise as nontrivial UV fixed points of perturbatively nonrenormalizable Yang-Mills theories, thereby making them more directly accessible to quantitative analysis...
March 10, 2017: Physical Review Letters
https://www.readbyqxmd.com/read/28294712/frequency-and-chunking-in-derived-words-a-parametric-fmri-study
#8
Alice Blumenthal-Dramé, Volkmar Glauche, Tobias Bormann, Cornelius Weiller, Mariacristina Musso, Bernd Kortmann
In usage-based linguistic theories, the assumption that high-frequency language strings are mentally represented as unitary chunks has been invoked to account for a wide range of phenomena. However, neurocognitive evidence in support of this assumption is still lacking. In line with Gestalt psychological assumptions, we propose that a language string qualifies as a chunk if the following two conditions are simultaneously satisfied: The perception of the whole string does not involve strong activation of its individual component parts, but the component parts in isolation strongly evoke the whole...
March 15, 2017: Journal of Cognitive Neuroscience
https://www.readbyqxmd.com/read/28275766/minimum-free-energy-paths-for-the-self-organization-of-polymer-brushes
#9
Ignacio Gleria, Esteban Mocskos, Mario Tagliazucchi
A methodology to calculate minimum free-energy paths based on the combination of a molecular theory and the improved string method is introduced and applied to study the self-organization of polymer brushes under poor solvent conditions. Polymer brushes in a poor solvent cannot undergo macroscopic phase separation due to the physical constraint imposed by the grafting points; therefore, they microphase separate forming aggregates. Under some conditions, the theory predicts that the homogeneous brush and the aggregates can exist as two different minima of the free energy...
March 9, 2017: Soft Matter
https://www.readbyqxmd.com/read/28250099/computing-exponentially-faster-implementing-a-non-deterministic-universal-turing-machine-using-dna
#10
Andrew Currin, Konstantin Korovin, Maria Ababi, Katherine Roper, Douglas B Kell, Philip J Day, Ross D King
The theory of computer science is based around universal Turing machines (UTMs): abstract machines able to execute all possible algorithms. Modern digital computers are physical embodiments of classical UTMs. For the most important class of problem in computer science, non-deterministic polynomial complete problems, non-deterministic UTMs (NUTMs) are theoretically exponentially faster than both classical UTMs and quantum mechanical UTMs (QUTMs). However, no attempt has previously been made to build an NUTM, and their construction has been regarded as impossible...
March 2017: Journal of the Royal Society, Interface
https://www.readbyqxmd.com/read/28243670/narrative-review-of-frameworks-for-translating-research-evidence-into-policy-and-practice
#11
Andrew J Milat, Ben Li
BACKGROUND: A significant challenge in research translation is that interested parties interpret and apply the associated terms and conceptual frameworks in different ways. The purpose of this review was to: a) examine different research translation frameworks; b) examine the similarities and differences between the frameworks; and c) identify key strengths and weaknesses of the models when they are applied in practice. METHODS: The review involved a keyword search of PubMed...
February 15, 2017: Public Health Research & Practice
https://www.readbyqxmd.com/read/28207632/are-we-ready-for-epitope-based-hla-matching-in-clinical-organ-transplantation
#12
Rene J Duquesnoy
This overview describes recent developments demonstrating the significance of epitopes in HLA antibody responses and matching for organ transplantation. HLA epitopes are defined by molecular modeling and amino acid comparisons between HLA alleles and the HLAMatchmaker algorithm considers eplets as essential components. Each allele represents a distinct string of eplets and matching is done by aligning donor and recipient strings. Evidence is summarized how mismatched eplet loads affect antibody responses and transplant outcomes...
February 15, 2017: Transplantation
https://www.readbyqxmd.com/read/28155662/an-ensemble-micro-neural-network-approach-for-elucidating-interactions-between-zinc-finger-proteins-and-their-target-dna
#13
Shayoni Dutta, Spandan Madan, Harsh Parikh, Durai Sundar
BACKGROUND: The ability to engineer zinc finger proteins binding to a DNA sequence of choice is essential for targeted genome editing to be possible. Experimental techniques and molecular docking have been successful in predicting protein-DNA interactions, however, they are highly time and resource intensive. Here, we present a novel algorithm designed for high throughput prediction of optimal zinc finger protein for 9 bp DNA sequences of choice. In accordance with the principles of information theory, a subset identified by using K-means clustering was used as a representative for the space of all possible 9 bp DNA sequences...
December 22, 2016: BMC Genomics
https://www.readbyqxmd.com/read/28141523/the-plausibility-of-a-string-quartet-performance-in-virtual-reality
#14
Ilias Bergstrom, Sergio Azevedo, Panos Papiotis, Nuno Saldanha, Mel Slater
We describe an experiment that explores the contribution of auditory and other features to the illusion of plausibility in a virtual environment that depicts the performance of a string quartet. 'Plausibility' refers to the component of presence that is the illusion that the perceived events in the virtual environment are really happening. The features studied were: Gaze (the musicians ignored the participant, the musicians sometimes looked towards and followed the participant's movements), Sound Spatialization (Mono, Stereo, Spatial), Auralization (no sound reflections, reflections corresponding to a room larger than the one perceived, reflections that exactly matched the virtual room), and Environment (no sound from outside of the room, birdsong and wind corresponding to the outside scene)...
January 27, 2017: IEEE Transactions on Visualization and Computer Graphics
https://www.readbyqxmd.com/read/28128622/search-for-an-ultralight-scalar-dark-matter-candidate-with-the-auriga-detector
#15
Antonio Branca, Michele Bonaldi, Massimo Cerdonio, Livia Conti, Paolo Falferi, Francesco Marin, Renato Mezzena, Antonello Ortolan, Giovanni A Prodi, Luca Taffarello, Gabriele Vedovato, Andrea Vinante, Stefano Vitale, Jean-Pierre Zendri
A search for a new scalar field, called moduli, has been performed using the cryogenic resonant-mass AURIGA detector. Predicted by string theory, moduli may provide a significant contribution to the dark matter (DM) component of our Universe. If this is the case, the interaction of ordinary matter with the local DM moduli, forming the Galaxy halo, will cause an oscillation of solid bodies with a frequency corresponding to the mass of moduli. In the sensitive band of AURIGA, some 100 Hz at around 1 kHz, the expected signal, with Q=△f/f∼10^{6}, is a narrow peak, △f∼1  mHz...
January 13, 2017: Physical Review Letters
https://www.readbyqxmd.com/read/28121936/fatal-remote-cerebellar-hemorrhage-after-supratentorial-unruptured-aneurysm-surgery-in-patient-with-previous-cerebellar-infarction-a-case-report
#16
Eun-Jeong Koh, Jung-Soo Park
RATIONALE: Remote cerebellar hemorrhage (RCH) is a rare complication of supratentorial and spinal surgeries, seldom requiring intervention but occasionally causing significant morbidity or even mortality. Although a number of theories have been proposed, the exact pathophysiology of RCH remains incompletely understood. PATIENT CONCERNS: We present a 62-year-old patient with RCH encountered following surgical clipping of an unruptured middle cerebral artery bifurcation aneurysm in a patient with previous cerebellar infarction...
January 2017: Medicine (Baltimore)
https://www.readbyqxmd.com/read/28106446/exacerbating-the-cosmological-constant-problem-with-interacting-dark-energy-models
#17
M C David Marsh
Future cosmological surveys will probe the expansion history of the Universe and constrain phenomenological models of dark energy. Such models do not address the fine-tuning problem of the vacuum energy, i.e., the cosmological constant problem (CCP), but can make it spectacularly worse. We show that this is the case for "interacting dark energy" models in which the masses of the dark matter states depend on the dark energy sector. If realized in nature, these models have far-reaching implications for proposed solutions to the CCP that require the number of vacua to exceed the fine-tuning of the vacuum energy density...
January 6, 2017: Physical Review Letters
https://www.readbyqxmd.com/read/28101923/how-suboptimal-is-suboptimal-choice
#18
Jay E Hinnenkamp, Timothy A Shahan, Gregory J Madden
In a frequently used suboptimal-choice procedure pigeons choose between an alternative that delivers three food pellets with p = 1.0 and an alternative that delivers ten pellets with p = 0.2. Because pigeons reliably choose the probabilistic (suboptimal) alternative, the procedure has been proposed as a nonhuman analog of human gambling. The present experiments were conducted to evaluate two potential threats to the validity of this procedure. Experiments 1 and 2 evaluated if pigeons obtained food at a lower unit price (i...
January 2017: Journal of the Experimental Analysis of Behavior
https://www.readbyqxmd.com/read/28054814/entrainment-to-an-auditory-signal-is-attention-involved
#19
Richard Kunert, Suzanne R Jongman
Many natural auditory signals, including music and language, change periodically. The effect of such auditory rhythms on the brain is unclear however. One widely held view, dynamic attending theory, proposes that the attentional system entrains to the rhythm and increases attention at moments of rhythmic salience. In support, 2 experiments reported here show reduced response times to visual letter strings shown at auditory rhythm peaks, compared with rhythm troughs. However, we argue that an account invoking the entrainment of general attention should further predict rhythm entrainment to also influence memory for visual stimuli...
January 2017: Journal of Experimental Psychology. General
https://www.readbyqxmd.com/read/28036207/new-solutions-for-non-abelian-cosmic-strings
#20
Mark Hindmarsh, Kari Rummukainen, David J Weir
We study the properties of classical vortex solutions in a non-Abelian gauge theory. A system of two adjoint Higgs fields breaks the SU(2) gauge symmetry to Z_{2}, producing 't Hooft-Polyakov monopoles trapped on cosmic strings, termed beads; there are two charges of monopole and two degenerate string solutions. The strings break an accidental discrete Z_{2} symmetry of the theory, explaining the degeneracy of the ground state. Further symmetries of the model, not previously appreciated, emerge when the masses of the two adjoint Higgs fields are degenerate...
December 16, 2016: Physical Review Letters
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