905 research outputs found

    Drugs, Crime, and the Epigenetics of Hedonic Allostasis

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    Researchers have found staggering numbers of drug addicts among incarcerated populations and have conceded that drug abuse is an important correlate of deviant behavior, but few included an understanding of the biological process leading to drug addiction. Chronic drug abuse and criminality are housed within a much broader propensity of some individuals to engage in a variety of antisocial behaviors, and this article clarifies the link and proposed shared mechanisms between criminal behavior and drug abuse through a molecular-genetic and neurobiological lens. Multiple genes, enzymes, and transcription factors are involved in drug addition, with over 100 genes known to be changed with repeated cocaine exposure. The epigenetics of drug addiction, with a specific emphasis on the addiction of cocaine, are brought under examination here. The epigenetic processes of methylation and acetylation are described and their long term effects are illustrated within the processes of allostatic changes to the brain. After the establishment of the rudiments of epigenetic operation and their effects, a discussion is presented on the opponent process and incentive-sensitization models of drug addiction and how all of these factors are impacted by socio-cultural variables

    Solutions of Higher Dimensional Gauss-Bonnet FRW Cosmology

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    We examine the effect on cosmological evolution of adding a Gauss-Bonnet term to the standard Einstein-Hilbert action for a (1 + 3)+ d dimensional Friedman-Robertson-Walker (FRW) metric. By assuming that the additional dimensions compactify as a power law as the usual 3 spatial dimensions expand, we solve the resulting dynamical equations and find that the solution may be of either de Sitter or Kasner form depending upon whether the Gauss-Bonnet term or the Einstein term dominates.Comment: 10 pages, references added/corrected, accepted for publication in General Relativity and Gravitatio

    Observation of quantum-Hall effect in gated epitaxial graphene grown on SiC (0001)

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    Epitaxial graphene films were formed on the Si-face of semi-insulating 4H-SiC substrates by a high temperature sublimation process. A high-k gate stack on epitaxial graphene is realized by inserting a fully oxidized nanometer thin aluminum film as a seeding layer followed by an atomic-layer deposition process. The electrical properties of epitaxial graphene films are sustained after gate stack formation without significant degradation. At low temperatures, the quantum-Hall effect in Hall resistance is observed along with pronounced Shubnikov-de Hass oscillations in diagonal magneto-resistance of gated epitaxial graphene on SiC (0001).Comment: 2 new references adde

    Protein Phase Diagrams II: Nonideal Behavior of Biochemical Reactions in the Presence of Osmolytes

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    AbstractIn the age of biochemical systems biology, proteomics, and high throughput methods, the thermodynamic quantification of cytoplasmatic reaction networks comes into reach of the current generation of scientists. What is needed to efficiently extract the relevant information from the raw data is a robust tool for evaluating the number and stoichiometry of all observed reactions while providing a good estimate of the thermodynamic parameters that determine the molecular behavior. The recently developed phase-diagram method, strictly speaking a graphical representation of linkage or Maxwell Relations, offers such capabilities. Here, we extend the phase diagram method to nonideal conditions. For the sake of simplicity, we choose as an example a reaction system involving the protein RNase A, its inhibitor CMP, the osmolyte urea, and water. We investigate this system as a function of the concentrations of inhibitor and osmolyte at different temperatures ranging from 280K to 340K. The most interesting finding is that the protein-inhibitor binding equilibrium depends strongly on the urea concentration—by orders-of-magnitude more than expected from urea-protein interaction alone. Moreover, the m-value of ligand binding is strongly concentration-dependent, which is highly unusual. It is concluded that the interaction between small molecules like urea and CMP can significantly contribute to cytoplasmic nonideality. Such a finding is highly significant because of its impact on renal tissue where high concentrations of cosolutes occur regularly

    Expansion-induced contribution to the precession of binary orbits

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    We point out the existence of new effects of global spacetime expansion on local binary systems. In addition to a possible change of orbital size, there is a contribution to the precession of elliptic orbits, to be added to the well-known general relativistic effect in static spacetimes, and the eccentricity can change. Our model calculations are done using geodesics in a McVittie metric, representing a localized system in an asymptotically Robertson-Walker spacetime; we give a few numerical estimates for that case, and indicate ways in which the model should be improved.Comment: revtex, 7 pages, no figures; revised for publication in Classical and Quantum Gravity, with minor changes in response to referees' comment

    Semiclassical States in Quantum Cosmology: Bianchi I Coherent States

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    We study coherent states for Bianchi type I cosmological models, as examples of semiclassical states for time-reparametrization invariant systems. This simple model allows us to study explicitly the relationship between exact semiclassical states in the kinematical Hilbert space and corresponding ones in the physical Hilbert space, which we construct here using the group averaging technique. We find that it is possible to construct good semiclassical physical states by such a procedure in this model; we also discuss the sense in which the original kinematical states may be a good approximation to the physical ones, and the situations in which this is the case. In addition, these models can be deparametrized in a natural way, and we study the effect of time evolution on an "intrinsic" coherent state in the reduced phase space, in order to estimate the time for this state to spread significantly.Comment: 21 pages, 1 figure; Version to be published in CQG; The discussion has been slightly reorganized, two references added, and some typos correcte

    Quantum Gravitational Corrections to the Real Klein-Gordon Field in the Presence of a Minimal Length

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    The (D+1)-dimensional (β,β)(\beta,\beta')-two-parameter Lorentz-covariant deformed algebra introduced by Quesne and Tkachuk [C. Quesne and V. M. Tkachuk, J. Phys. A: Math. Gen. \textbf {39}, 10909 (2006).], leads to a nonzero minimal uncertainty in position (minimal length). The Klein-Gordon equation in a (3+1)-dimensional space-time described by Quesne-Tkachuk Lorentz-covariant deformed algebra is studied in the case where β=2β\beta'=2\beta up to first order over deformation parameter β\beta. It is shown that the modified Klein-Gordon equation which contains fourth-order derivative of the wave function describes two massive particles with different masses. We have shown that physically acceptable mass states can only exist for β<18m2c2\beta<\frac{1}{8m^{2}c^{2}} which leads to an isotropic minimal length in the interval 1017m<(Xi)0<1015m10^{-17}m<(\bigtriangleup X^{i})_{0}<10^{-15}m. Finally, we have shown that the above estimation of minimal length is in good agreement with the results obtained in previous investigations.Comment: 10 pages, no figur

    Hawking Temperature in Taub-NUT (A)dS spaces via the Generalized Uncertainty Principle

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    Using the extended forms of the Heisenberg uncertainty principle from string theory and the quantum gravity theory, we drived Hawking temperature of a Taub-Nut-(A)dS black hole. In spite of their distinctive natures such as asymptotically locally flat and breakdown of the area theorem of the horizon for the black holes, we show that the corrections to Hawking temperature by the generalized versions of the the Heisenberg uncertainty principle increases like the Schwarzschild-(A)dS black hole and give the reason why the Taub-Nut-(A)dS metric may have AdS/CFT dual picture.Comment: version published in General Relativity and Gravitatio
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