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String theory

Peng-Wei Zhu, Luguang Chen
In this paper, we investigate the micelle (charge)-constrained collapse of a spherical poly(N-isopropylacrylamide) (PNIPAM) brush. The system is an example of the transition of a short-length neutral polymer from a stretched state to a folded state under the constraint of long-range electrostatic repulsion. The collapsed state is described as an anisotropic globule comprising a cascade of rod-like or hairpin bundles. A critical aggregation number of bound micelles is obtained to distinguish the charge-induced deformation of the globule, which provides a guideline to characterize globule dimensions under different strengths of electrostatic interaction...
November 20, 2017: Physical Chemistry Chemical Physics: PCCP
Antonio Tinti, Alberto Giacomello, Yaroslav Grosu, Carlo Massimo Casciola
Heterogeneous systems composed of hydrophobic nanoporous materials and water are capable, depending on their characteristics, of efficiently dissipating (dampers) or storing ("molecular springs") energy. However, it is difficult to predict their properties based on macroscopic theories-classical capillarity for intrusion and classical nucleation theory (CNT) for extrusion-because of the peculiar behavior of water in extreme confinement. Here we use advanced molecular dynamics techniques to shed light on these nonclassical effects, which are often difficult to investigate directly via experiments, owing to the reduced dimensions of the pores...
November 14, 2017: Proceedings of the National Academy of Sciences of the United States of America
Jiani Chen, Carel Ten Cate
Many animal species can detect dependencies between adjacent visual or auditory items in a string. Compared with adjacent dependencies, detecting nonadjacent dependencies, as present in linguistic constructions, is more challenging as this requires detecting a relation between items irrespective of the number and nature of the intervening items. There is limited evidence that nonhuman animals can detect such dependencies. An animal group in which such abilities might be expected is songbirds, which have learned songs consisting of a series of vocal elements given in specific sequences...
July 2017: Journal of Experimental Psychology. Animal Learning and Cognition
Michael Atiyah, Maciej Dunajski, Lionel J Mason
We review aspects of twistor theory, its aims and achievements spanning the last five decades. In the twistor approach, space-time is secondary with events being derived objects that correspond to compact holomorphic curves in a complex threefold-the twistor space. After giving an elementary construction of this space, we demonstrate how solutions to linear and nonlinear equations of mathematical physics-anti-self-duality equations on Yang-Mills or conformal curvature-can be encoded into twistor cohomology...
October 2017: Proceedings. Mathematical, Physical, and Engineering Sciences
V Swaminathan, Gangothri Rajaram, V Abhishek, Boosi Shashank Reddy, K Kannan
The sequencing by hybridization (SBH) of determining the order in which nucleotides should occur on a DNA string is still under discussion for enhancements on computational intelligence although the next generation of DNA sequencing has come into existence. In the last decade, many works related to graph theory-based DNA sequencing have been carried out in the literature. This paper proposes a method for SBH by integrating hypergraph with genetic algorithm (HGGA) for designing a novel analytic technique to obtain DNA sequence from its spectrum...
November 6, 2017: Interdisciplinary Sciences, Computational Life Sciences
Rivona Harricharan, Oualid Abboussi, William M U Daniels
Over the years, drug addiction has proven to be a perplexing conundrum for scientists. In attempts to decipher the components of the puzzle, multiple theories of addiction have been proposed. While these theories have assisted in providing essential fundamental information, current research recommends that a new theory needs to be presented taking into consideration the results of recent developments in the fields of neuroimmunology, genetics, and neuropsychiatry. After extensively examining the published literature, we propose in this review that neuroinflammation and hypothalamic functioning strongly underpin addictive behavior...
2017: Progress in Brain Research
Ashley A Blackwell, William L Widick, Joseph L Cheatwood, Ian Q Whishaw, Douglas G Wallace
String-pulling by the rat is a bimanual act, in which an upright animal retrieves a piece of food attached to the end of the string by downward hand-over-hand movements. The present study compared the movements of string-pulling, using topographic and kinematic measures of hand movement, in control rats and rats with unilateral sensorimotor motor cortex lesion produced by removal of the pia matter. In the first week following devascularization, the rhythmicity and accuracy of string-pulling movements decomposed; however, thereafter the rhythm of bilateral alternation was restored...
October 14, 2017: Behavioural Brain Research
Dennis Ott
This Perspective traces the evolution of certain central notions in the theory of Generative Grammar (GG). The founding documents of the field suggested a relation between the grammar, construed as recursively enumerating an infinite set of sentences, and the idealized native speaker that was essentially equivalent to the relation between a formal language (a set of well-formed formulas) and an automaton that recognizes strings as belonging to the language or not. But this early view was later abandoned, when the focus of the field shifted to the grammar's strong generative capacity as recursive generation of hierarchically structured objects as opposed to strings...
2017: Frontiers in Psychology
Leif D Jacobson, Art D Bochevarov, Mark A Watson, Thomas F Hughes, David Rinaldo, Stephan Ehrlich, Thomas B Steinbrecher, S Vaitheeswaran, Dean M Philipp, Mathew D Halls, Richard A Friesner
Transition state search is at the center of multiple types of computational chemical predictions related to mechanistic investigations, reactivity and regioselectivity predictions, and catalyst design. The process of finding transition states in practice is, however, a laborious multistep operation that requires significant user involvement. Here, we report a highly automated workflow designed to locate transition states for a given elementary reaction with minimal setup overhead. The only essential inputs required from the user are the structures of the separated reactants and products...
October 17, 2017: Journal of Chemical Theory and Computation
P Jurcevic, H Shen, P Hauke, C Maier, T Brydges, C Hempel, B P Lanyon, M Heyl, R Blatt, C F Roos
The theory of phase transitions represents a central concept for the characterization of equilibrium matter. In this work we study experimentally an extension of this theory to the nonequilibrium dynamical regime termed dynamical quantum phase transitions (DQPTs). We investigate and measure DQPTs in a string of ions simulating interacting transverse-field Ising models. During the nonequilibrium dynamics induced by a quantum quench we show for strings of up to 10 ions the direct detection of DQPTs by revealing nonanalytic behavior in time...
August 25, 2017: Physical Review Letters
Tin Sulejmanpasic, Hui Shao, Anders W Sandvik, Mithat Ünsal
In a spontaneously dimerized quantum antiferromagnet, spin-1/2 excitations (spinons) are confined in pairs by strings akin to those confining quarks in non-Abelian gauge theories. The system has multiple degenerate ground states (vacua) and domain walls between regions of different vacua. For two vacua, we demonstrate that spinons on a domain wall are liberated, in a mechanism strikingly similar to domain-wall deconfinement of quarks in variants of quantum chromodynamics. This observation not only establishes a novel phenomenon in quantum magnetism, but also provides a new direct link between particle physics and condensed-matter physics...
September 1, 2017: Physical Review Letters
Joseph Novak, Mehmet Ozkan, Yi Pang, Gabriele Tartaglino-Mazzucchelli
The supersymmetrization of curvature squared terms is important in the study of the low-energy limit of compactified superstrings where a distinguished role is played by the Gauss-Bonnet combination, which is ghost-free. In this Letter, we construct its off-shell N=(1,0) supersymmetrization in six dimensions for the first time. By studying this invariant together with the supersymmetric Einstein-Hilbert term, we confirm and extend known results of the α^{'}-corrected string theory compactified to six dimensions...
September 15, 2017: Physical Review Letters
S S AbdusSalam
In this article, we show that making global fits of string theory model parameters to data is an interesting mechanism for probing, mapping and forecasting connections of the theory to real world physics. We considered a large volume scenario (LVS) with D3-brane matter fields and supersymmetry breaking. A global fit of the parameters to low-energy data shows that the set of LVS models are associated with light gluinos which are quasi-degenerate with the neutralinos and charginos they can promptly decay into, and thus they are possibly hidden to current LHC gluino search strategies...
2017: European Physical Journal. C, Particles and Fields
Yun Tian, Xiaofei Xu, Jianzhong Wu
We report an efficient computational procedure for rapid and accurate prediction of the self-diffusivity of gas molecules in nanoporous materials by implementing the transition state theory for intercage hopping at infinite dilution with the string method in conjunction with the excess-entropy scaling for predicting gas diffusion coefficients at finite loadings. The theoretical procedure has been calibrated with molecular dynamics simulations for the diffusion coefficients of methane and hydrogen gases in representative nanoporous materials including metal organic frameworks and zeolites...
September 26, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
Jonah Musa, Chad J Achenbach, Linda C O'Dwyer, Charlesnika T Evans, Megan McHugh, Lifang Hou, Melissa A Simon, Robert L Murphy, Neil Jordan
BACKGROUND: Although cervical cancer is largely preventable through screening, detection and treatment of precancerous abnormalities, it remains one of the top causes of cancer-related morbidity and mortality globally. OBJECTIVES: The objective of this systematic review is to understand the evidence of the effect of cervical cancer education compared to control conditions on cervical cancer screening rates in eligible women population at risk of cervical cancer...
2017: PloS One
Xiaoxia He, Yan Shen, Francisco R Hung, Erik E Santiso
Classical molecular dynamics simulations were used to study the nucleation of the crystal phase of the ionic liquid [dmim(+)][Cl(-)] from its supercooled liquid phase, both in the bulk and in contact with a graphitic surface of D = 3 nm. By combining the string method in collective variables [Maragliano et al., J. Chem. Phys. 125, 024106 (2006)], with Markovian milestoning with Voronoi tessellations [Maragliano et al., J. Chem. Theory Comput. 5, 2589-2594 (2009)] and order parameters for molecular crystals [Santiso and Trout, J...
December 7, 2016: Journal of Chemical Physics
Steven M Rosen
This paper carries forward the author's contribution to PBMP's previous special issue on Integral Biomathics (Rosen 2015). In the earlier paper, the crisis in contemporary theoretical physics was described and it was demonstrated that the problem can be addressed effectively only by shifting the foundations of physics from objectivist Cartesian philosophy to phenomenological philosophy. To that end, a phenomenological string theory was proposed based on qualitative topology and hypercomplex numbers. The current presentation takes this further by delving into the ancient Chinese origin of phenomenological string theory...
July 4, 2017: Progress in Biophysics and Molecular Biology
Teresa Schubert, Nicholas Badcock, Saskia Kohnen
Letter recognition and digit recognition are critical skills for literate adults, yet few studies have considered the development of these skills in children. We conducted a nine-alternative forced-choice (9AFC) partial report task with strings of letters and digits, with typographical symbols (e.g., $, @) as a control, to investigate the development of identity and position processing in children. This task allows for the delineation of identity processing (as overall accuracy) and position coding (as the proportion of position errors)...
June 9, 2017: Journal of Experimental Child Psychology
Haipeng Wei, Liyan Zhang, Hoa Phan, Xiaobo Huang, Tun Seng Herng, Jun Zhou, Wangdong Zeng, Jun Ding, Shenglian Luo, Jishan Wu, Zebing Zeng
Organic π-extended radicals display unique electronic structures, and could be used as promising functional materials. However, design and synthesis of stable radicals are challenging for chemists due to their high reactivity. In this work, we synthesized a stable N-annulated perylene-bridged bisphenoxyl diradicaloid, and its complex with Lewis acid boron trifluoride. Their ground-state geometric and electronic structures were systematically studied by various experimental methods, including X-ray crystallographic analysis, variable-temperature NMR spectroscopy, electron-spin resonance spectroscopy (ESR), and superconducting quantum interference device (SQUID) measurements, supported by density functional theory...
May 13, 2017: Chemistry: a European Journal
Tomohiko G Sano, Tetsuo Yamaguchi, Hirofumi Wada
The morphology of an elastic strip subject to vertical compressive stress on a frictional rigid substrate is investigated by a combination of theory and experiment. We find a rich variety of morphologies, which-when the bending elasticity dominates over the effect of gravity-are classified into three distinct types of states: pinned, partially slipped, and completely slipped, depending on the magnitude of the vertical strain and the coefficient of static friction. We develop a theory of elastica under mixed clamped-hinged boundary conditions combined with the Coulomb-Amontons friction law and find excellent quantitative agreement with simulations and controlled physical experiments...
April 28, 2017: Physical Review Letters
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