2,256 research outputs found

    Automated tracking of the Florida manatee (Trichechus manatus)

    Get PDF
    The electronic, physical, biological and environmental factors involved in the automated remote tracking of the Florida manatee (Trichechus manatus) are identified. The current status of the manatee as an endangered species is provided. Brief descriptions of existing tracking and position locating systems are presented to identify the state of the art in these fields. An analysis of energy media is conducted to identify those with the highest probability of success for this application. Logistic questions such as the means of attachment and position of any equipment to be placed on the manatee are also investigated. Power sources and manateeborne electronics encapsulation techniques are studied and the results of a compter generated DF network analysis are summarized

    Modern Michelson-Morley experiment using cryogenic optical resonators

    Full text link
    We report on a new test of Lorentz invariance performed by comparing the resonance frequencies of two orthogonal cryogenic optical resonators subject to Earth's rotation over 1 year. For a possible anisotropy of the speed of light c, we obtain 2.6 +/- 1.7 parts in 10^15. Within the Robertson-Mansouri-Sexl test theory, this implies an isotropy violation parameter beta - delta - 1/2 of -2.2 +/- 1.5 parts in 10^9, about three times lower than the best previous result. Within the general extension of the standard model of particle physics, we extract limits on 7 parameters at accuracies down to a part in 10^15, improving the best previous result by about two orders of magnitude

    Experiences of parenting and clinical intervention for mothers affected by personality disorder: a pilot qualitative study combining parent and clinician perspectives

    Get PDF
    Background: Evidence-based parenting programmes are recommended for the treatment of child mental health difficulties. Families with complex psychosocial needs show poorer retention and outcomes when participating in standard parenting programmes. The Helping Families Programme (HFP) is a 16-week community-based parenting intervention designed to meet the needs of these families, including families with parental personality disorder. This study aimed to explore the help seeking and participatory experiences of parents with a diagnosis of personality disorder. It further aimed to examine the acceptability of referral and intervention processes for the HFP from the perspectives of (i) clinicians referring into the programme; and (ii) referred parents. Method: Semi-structured interviews were conducted with parents recruited to receive HFP (n = 5) as part of a research case series and the referring NHS child and adolescent mental health service (CAMHS) clinicians (n = 5). Transcripts were analysed using Interpretive Phenomenological Analysis. Results: Four themes were identified for parents: (i) the experience of parenthood, (ii) being a parent affected by personality disorder, (iii) experience of the intervention, and (iv) qualities of helping. Three themes emerged for clinicians: (i) challenges of addressing parental need, (ii) experience of engaging parents with personality disorders and (iii) limited involvement during HFP. Comparison of parent and clinician themes led to the identification of two key interlinked themes: (i) concerns prior to receiving the intervention, and (ii) the challenges of working together without a mutual understanding. Conclusions: This pilot study identifies potentially significant challenges of working with parents affected by personality disorder and engaging them in HFP and other similar interventions. Results have important wider clinical implications by highlighting potential barriers to engagement and participation and providing insights on how these barriers might be overcome. Findings have been used to inform the referral and intervention processes of a pilot RCT and further intervention development

    Superconformal Black Hole Quantum Mechanics

    Full text link
    In recent work, the superconformal quantum mechanics describing D0 branes in the AdS_2xS^2xCY_3 attractor geometry of a Calabi-Yau black hole with D4 brane charges p^A has been constructed and found to contain a large degeneracy of chiral primary bound states. In this paper it is shown that the asymptotic growth of chiral primaries for N D0 branes exactly matches the Bekenstein-Hawking area law for a black hole with D4 brane charge p^A and D0 brane charge N. This large degeneracy arises from D0 branes in lowest Landau levels which tile the CY_3xS^2 horizon. It is conjectured that such a multi-D0 brane CFT1 is holographically dual to IIA string theory on AdS_2xS^2xCY_3.Comment: 8 page

    Optical cavity tests of Lorentz invariance for the electron

    Full text link
    A hypothetical violation of Lorentz invariance in the electrons' equation of motion (expressed within the Lorentz-violating extension of the standard model) leads to a change of the geometry of crystals and thus shifts the resonance frequency of an electromagnetic cavity. This allows experimental tests of Lorentz invariance of the electron sector of the standard model. The material dependence of the effect allows to separate it from an additional shift caused by Lorentz violation in electrodynamics, and to place independent limits on both effects. From present experiments, upper limits on Lorentz violation in the electrons' kinetic energy term are deduced.Comment: 17 pages revte

    The visual orbits of the spectroscopic binaries HD 6118 and HD 27483 from the Palomar Testbed Interferometer

    Full text link
    We present optical interferometric observations of two double-lined spectroscopic binaries, HD 6118 and HD 27483, taken with the Palomar Testbed Interferometer (PTI) in the K band. HD 6118 is one of the most eccentric spectroscopic binaries and HD 27483 a spectroscopic binary in the Hyades open cluster. The data collected with PTI in 2001-2002 allow us to determine astrometric orbits and when combined with the radial velocity measurements derive all physical parameters of the systems. The masses of the components are 2.65 +/- 0.27 M_Sun and 2.36 +/- 0.24 M_Sun for HD 6118 and 1.38 +/- 0.13 M_Sun and 1.39 +/- 0.13 M_Sun for HD 27483. The apparent semi-major axis of HD 27483 is only 1.2 mas making it the closest binary successfully observed with an optical interferometer.Comment: submitted to Ap

    Space missions to detect the cosmic gravitational-wave background

    Get PDF
    It is thought that a stochastic background of gravitational waves was produced during the formation of the universe. A great deal could be learned by measuring this Cosmic Gravitational-wave Background (CGB), but detecting the CGB presents a significant technological challenge. The signal strength is expected to be extremely weak, and there will be competition from unresolved astrophysical foregrounds such as white dwarf binaries. Our goal is to identify the most promising approach to detect the CGB. We study the sensitivities that can be reached using both individual, and cross-correlated pairs of space based interferometers. Our main result is a general, coordinate free formalism for calculating the detector response that applies to arbitrary detector configurations. We use this general formalism to identify some promising designs for a GrAvitational Background Interferometer (GABI) mission. Our conclusion is that detecting the CGB is not out of reach.Comment: 22 pages, 7 figures, IOP style, References Adde

    Tests of relativity using a microwave resonator

    Get PDF
    The frequencies of a cryogenic sapphire oscillator and a hydrogen maser are compared to set new constraints on a possible violation of Lorentz invariance. We determine the variation of the oscillator frequency as a function of its orientation (Michelson-Morley test) and of its velocity (Kennedy-Thorndike test) with respect to a preferred frame candidate. We constrain the corresponding parameters of the Mansouri and Sexl test theory to δβ+1/2=(1.5±4.2)×109\delta - \beta + 1/2 = (1.5\pm 4.2) \times 10^{-9} and βα1=(3.1±6.9)×107\beta - \alpha - 1 = (-3.1\pm 6.9) \times 10^{-7} which is equivalent to the best previous result for the former and represents a 30 fold improvement for the latter.Comment: 8 pages, 2 figures, submitted to Physical Review Letters (October 3, 2002

    Black Hole Thermodynamics from Near-Horizon Conformal Quantum Mechanics

    Full text link
    The thermodynamics of black holes is shown to be directly induced by their near-horizon conformal invariance. This behavior is exhibited using a scalar field as a probe of the black hole gravitational background, for a general class of metrics in D spacetime dimensions (with D4D \geq 4). The ensuing analysis is based on conformal quantum mechanics, within a hierarchical near-horizon expansion. In particular, the leading conformal behavior provides the correct quantum statistical properties for the Bekenstein-Hawking entropy, with the near-horizon physics governing the thermodynamic properties from the outset. Most importantly: (i) this treatment reveals the emergence of holographic properties; (ii) the conformal coupling parameter is shown to be related to the Hawking temperature; and (iii) Schwarzschild-like coordinates, despite their ``coordinate singularity,''can be used self-consistently to describe the thermodynamics of black holes.Comment: 16 pages. Sections 2 and 3 and sections 4 and 5 of version 1 were merged and reduced; a few typos were corrected. The original central results and equations remain unchange

    Finite size effects and error-free communication in Gaussian channels

    Get PDF
    The efficacy of a specially constructed Gallager-type error-correcting code to communication in a Gaussian channel is being examined. The construction is based on the introduction of complex matrices, used in both encoding and decoding, which comprise sub-matrices of cascading connection values. The finite size effects are estimated for comparing the results to the bounds set by Shannon. The critical noise level achieved for certain code-rates and infinitely large systems nearly saturates the bounds set by Shannon even when the connectivity used is low
    corecore