14,635 research outputs found

    Standard Transistor Array (STAR). Volume 1, addendum 1: CAPSTAR user's guide

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    The cell placement techniques developed for use with the standard transistor array were incorporated in the cell arrangement program for STAR (CAPSTAR). Instructions for use of this program are given

    Hands-on Gravitational Wave Astronomy: Extracting astrophysical information from simulated signals

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    In this paper we introduce a hands-on activity in which introductory astronomy students act as gravitational wave astronomers by extracting information from simulated gravitational wave signals. The process mimics the way true gravitational wave analysis will be handled by using plots of a pure gravitational wave signal. The students directly measure the properties of the simulated signal, and use these measurements to evaluate standard formulae for astrophysical source parameters. An exercise based on the discussion in this paper has been written and made publicly available online for use in introductory laboratory courses.Comment: 5 pages, 4 figures; submitted to Am. J. Phy

    Generalized Hurst exponent and multifractal function of original and translated texts mapped into frequency and length time series

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    A nonlinear dynamics approach can be used in order to quantify complexity in written texts. As a first step, a one-dimensional system is examined : two written texts by one author (Lewis Carroll) are considered, together with one translation, into an artificial language, i.e. Esperanto are mapped into time series. Their corresponding shuffled versions are used for obtaining a "base line". Two different one-dimensional time series are used here: (i) one based on word lengths (LTS), (ii) the other on word frequencies (FTS). It is shown that the generalized Hurst exponent h(q)h(q) and the derived f(α)f(\alpha) curves of the original and translated texts show marked differences. The original "texts" are far from giving a parabolic f(α)f(\alpha) function, - in contrast to the shuffled texts. Moreover, the Esperanto text has more extreme values. This suggests cascade model-like, with multiscale time asymmetric features as finally written texts. A discussion of the difference and complementarity of mapping into a LTS or FTS is presented. The FTS f(α)f(\alpha) curves are more opened than the LTS onesComment: preprint for PRE; 2 columns; 10 pages; 6 (multifigures); 3 Tables; 70 reference

    PVLAS experiment, star cooling and BBN constraints: Possible interpretation with temperature dependent gauge symmetry breaking

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    It is known that the kinetic mixing of photon and another U(1)_ex gauge boson can introduce millicharged particles. Millicharged particles ff of mass 0.1 eV can explain the PVLAS experiment. We suggest a temperature dependent gauge symmetry breaking of U(1)_ex for this idea to be consistent with astrophysical and cosmological constraints.Comment: 9 pages, 3 figue

    On the Miura map between the dispersionless KP and dispersionless modified KP hierarchies

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    We investigate the Miura map between the dispersionless KP and dispersionless modified KP hierarchies. We show that the Miura map is canonical with respect to their bi-Hamiltonian structures. Moreover, inspired by the works of Takasaki and Takebe, the twistor construction of solution structure for the dispersionless modified KP hierarchy is given.Comment: 19 pages, Latex, no figure

    Equation of state for Entanglement in a Fermi gas

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    Entanglement distance is the maximal separation between two entangled electrons in a degenerate electron gas. Beyond that distance, all entanglement disappears. We relate entanglement distance to degeneracy pressure both for extreme relativistic and non-relativistic systems, and estimate the entanglement distance in a white dwarf. Treating entanglement as a thermodynamical quantity, we relate the entropy of formation and concurrence to relative electron distance, pressure, and temperature, to form a new equation of state for entanglement.Comment: To appear in Phys. Rev. A., 4 pages, 1 figur

    Phase transition from quark-meson coupling hyperonic matter to deconfined quark matter

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    We investigate the possibility and consequences of phase transitions from an equation of state (EOS) describing nucleons and hyperons interacting via mean fields of sigma, omega, and rho mesons in the recently improved quark-meson coupling (QMC) model to an EOS describing a Fermi gas of quarks in an MIT bag. The transition to a mixed phase of baryons and deconfined quarks, and subsequently to a pure deconfined quark phase, is described using the method of Glendenning. The overall EOS for the three phases is calculated for various scenarios and used to calculate stellar solutions using the Tolman-Oppenheimer-Volkoff equations. The results are compared with recent experimental data, and the validity of each case is discussed with consequences for determining the species content of the interior of neutron stars.Comment: 12 pages, 14 figures; minor typos correcte

    Entropy of the FRW universe based on the generalized uncertainty principle

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    The statistical entropy of the FRW universe described by time-dependent metric is newly calculated using the brick wall method based on the general uncertainty principle with the minimal length. We can determine the minimal length with the Plank scale to obtain the entropy proportional to the area of the cosmological apparent horizon.Comment: 10 pages, accepted in Modern Physics Letters

    Microlensing of Kepler Stars as a Method of Detecting Primordial Black Hole Dark Matter

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    If the Dark Matter consists of primordial black holes (PBHs), we show that gravitational lensing of stars being monitored by NASA's Kepler search for extra-solar planets can cause significant numbers of detectable microlensing events. A search through the roughly 150,000 lightcurves would result in large numbers of detectable events for PBHs in the mass range 5 \ten{-10}\msun to \aten{-4}\msun. Non-detection of these events would close almost two orders of magnitude of the mass window for PBH dark matter. The microlensing rate is higher than previously noticed due to a combination of the exceptional photometric precision of the Kepler mission and the increase in cross section due to the large angular sizes of the relatively nearby Kepler field stars. We also present a new formalism for calculating optical depth and microlensing rates in the presence of large finite-source effects.Comment: 5 pages, 1 figur
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