14,358 research outputs found

    Evidence for a Non-Expanding Universe: Surface Brightness Data From HUDF

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    Surface brightness data can distinguish between a Friedman-Robertson-Walker expanding universe and a non-expanding universe. For surface brightness measured in AB magnitudes per angular area, all FRW models, regardless of cosmological parameters, predict that surface brightness declines with redshift as (z+1)^-3, while any non-expanding model predicts that surface brightness is constant with distance and thus with z. High-z UV surface brightness data for galaxies from the Hubble Ultra Deep Field and low-z data from GALEX are used to test the predictions of these two models up to z=6. A preliminary analysis presented here of samples observed at the same at-galaxy wavelengths in the UV shows that surface brightness is constant, mu=kz^0.026+-0.15, consistent with the non-expanding model. This relationship holds if distance is linearly proportional to z at all redshifts, but seems insensitive to the particular choice of d-z relationship. Attempts to reconcile the data with FRW predictions by assuming that high-z galaxies have intrinsically higher surface brightness than low-z galaxies appear to face insurmountable problems. The intrinsic FUV surface brightness required by the FRW models for high-z galaxies exceeds the maximum FUV surface brightness of any low-z galaxy by as much as a factor of 40. Dust absorption appears to make such extremely high intrinsic FUV surface brightness physically impossible. If confirmed by further analysis, the impossibility of such high-surface-brightness galaxies would rule out all FRW expanding universe (big bang) models.Comment: 16 pages, 9 figures, to be published in the Proceedings of the First Crisis in Cosmology Conference, AIP proceedings series typos correcte

    Modulator for tone and binary signals

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    Tones and binary information are transmitted as phase variations on a carrier wave of constant amplitude and frequency. The carrier and tones are applied to a balanced modulator for deriving an output signal including a pair of sidebands relative to the carrier. The carrier is phase modulated by a digital signal so that it is + or - 90 deg out of phase with the predetermined phase of the carrier. The carrier is combined in an algebraic summing device with the phase modulated signal and the balanced modulator output signal. The output of the algebraic summing device is hard limited to derive a constant amplitude and frequency signal having very narrow bandwidth requirements. At a receiver, the tones and binary data are detected with a phase locked loop having a voltage controlled oscillator driving a pair of orthogonal detection channels

    Etching method for photoresists or polymers

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    A method for etching or removing polymers, photoresists, and organic contaminants from a substrate is disclosed. The method includes creating a more reactive gas species by producing a plasma discharge in a reactive gas such as oxygen and contacting the resulting gas species with a sacrificial solid organic material such as polyethylene or polyvinyl fluoride, reproducing a highly reactive gas species, which in turn etches the starting polymer, organic contaminant, or photoresist. The sample to be etched is located away from the plasma glow discharge region so as to avoid damaging the substrate by exposure to high energy particles and electric fields encountered in that region. Greatly increased etching rates are obtained. This method is highly effective for etching polymers such as polyimides and photoresists that are otherwise difficult or slow to etch downstream from an electric discharge in a reactive gas

    Analysis of microwave radiometric measurements from Skylab

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    There are no author-identified significant results in this report

    Theory of the Jamming Transition at Finite Temperature

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    A theory for the microscopic structure and the vibrational properties of soft sphere glass at finite temperature is presented. With an effective potential, derived here, the phase diagram and vibrational properties are worked out around the Maxwell critical point at zero temperature TT and pressure pp. Variational arguments and effective medium theory identically predict a non-trivial temperature scale T∗∼p(2−a)/(1−a)T^*\sim p^{(2-a)/(1-a)} with a≈0.17a \approx 0.17 such that low-energy vibrational properties are hard-sphere like for T≳T∗T \gtrsim T^*, and zero-temperature soft-sphere like otherwise. However, due to crossovers in the equation of state relating TT, pp, and the packing fraction ϕ\phi, these two regimes lead to four regions where scaling behaviors differ when expressed in terms of TT and ϕ\phi. Scaling predictions are presented for the mean-squared displacement, characteristic frequency, shear modulus, and characteristic elastic length in all regions of the phase diagram.Comment: 8 pages + 3 pages S

    Athermal Nonlinear Elastic Constants of Amorphous Solids

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    We derive expressions for the lowest nonlinear elastic constants of amorphous solids in athermal conditions (up to third order), in terms of the interaction potential between the constituent particles. The effect of these constants cannot be disregarded when amorphous solids undergo instabilities like plastic flow or fracture in the athermal limit; in such situations the elastic response increases enormously, bringing the system much beyond the linear regime. We demonstrate that the existing theory of thermal nonlinear elastic constants converges to our expressions in the limit of zero temperature. We motivate the calculation by discussing two examples in which these nonlinear elastic constants play a crucial role in the context of elasto-plasticity of amorphous solids. The first example is the plasticity-induced memory that is typical to amorphous solids (giving rise to the Bauschinger effect). The second example is how to predict the next plastic event from knowledge of the nonlinear elastic constants. Using the results of this paper we derive a simple differential equation for the lowest eigenvalue of the Hessian matrix in the external strain near mechanical instabilities; this equation predicts how the eigenvalue vanishes at the mechanical instability and the value of the strain where the mechanical instability takes place.Comment: 17 pages, 2 figures

    Fluctuational susceptibility of ultracold bosons in the vicinity of condensation

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    We study the behaviour of ultracold bosonic gas in the critical region above the Bose-Einstein condensation in the presence of an artificial magnetic field, BartB_\mathrm{art}. We show that the condensate fluctuations above the critical temperature TcT_c cause the fluctuational susceptibility, χfl\chi _\mathrm{fl}, of a uniform gas to have a stronger power-law divergence than in an analogous superconducting system. Measuring such a divergence opens new ways of exploring critical properties of the ultracold gas and an opportunity of an accurate determination of TcT_c. We describe a method of measuring χfl\chi _\mathrm{fl} which requires a constant gradient in BartB_\mathrm{art} and suggest a way of creating such a field in experiment.Comment: 5 pages, 3 figures, 5 pages of Supplement; the text is rewritten and rearranged, and the figures are modifie

    Invisible Pixels Are Dead, Long Live Invisible Pixels!

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    Privacy has deteriorated in the world wide web ever since the 1990s. The tracking of browsing habits by different third-parties has been at the center of this deterioration. Web cookies and so-called web beacons have been the classical ways to implement third-party tracking. Due to the introduction of more sophisticated technical tracking solutions and other fundamental transformations, the use of classical image-based web beacons might be expected to have lost their appeal. According to a sample of over thirty thousand images collected from popular websites, this paper shows that such an assumption is a fallacy: classical 1 x 1 images are still commonly used for third-party tracking in the contemporary world wide web. While it seems that ad-blockers are unable to fully block these classical image-based tracking beacons, the paper further demonstrates that even limited information can be used to accurately classify the third-party 1 x 1 images from other images. An average classification accuracy of 0.956 is reached in the empirical experiment. With these results the paper contributes to the ongoing attempts to better understand the lack of privacy in the world wide web, and the means by which the situation might be eventually improved.Comment: Forthcoming in the 17th Workshop on Privacy in the Electronic Society (WPES 2018), Toronto, AC

    Theoretical considerations of some nonlinear aspects of hypersonic panel flutter Annual report, 1 Sep. 1967 - 31 Aug. 1968

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    Stability and postcritical response of infinite width panels on hinged supports due to aerodynamic loads at hypersonic spee
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