19,981 research outputs found

    Eye-controlled ''teletypewriter''

    Get PDF
    Oculometer provides dynamic measurement of subject's look direction, and its outputs can be used to generate visual display of his look pattern and/or to cause equipment operation associated with his lookpoint at given times. Measured eye-direction information could be used as control input at man/machine interface

    Bowen Measure From Heteroclinic Points

    Full text link
    We present a new construction of the entropy-maximizing, invariant probability measure on a Smale space (the Bowen measure). Our construction is based on points that are unstably equivalent to one given point, and stably equivalent to another: heteroclinic points. The spirit of the construction is similar to Bowen's construction from periodic points, though the techniques are very different. We also prove results about the growth rate of certain sets of heteroclinic points, and about the stable and unstable components of the Bowen measure. The approach we take is to prove results through direct computation for the case of a Shift of Finite type, and then use resolving factor maps to extend the results to more general Smale spaces

    Late cretaceous extensional tectonics and associated igneous activity on the northern margin of the Gulf of Mexico Basin

    Get PDF
    Major, dominantly compressional, orogenic episodes (Taconic, Acadian, Alleghenian) affected eastern North America during the Paleozoic. During the Mesozoic, in contrast, this same region was principally affected by epeirogenic and extensional tectonism; one episode of comparatively more intense tectonic activity involving extensive faulting, uplift, sedimentation, intrusion and effusion produced the Newark Series of eposits and fault block phenomena. This event, termed the Palisades Disturbance, took place during the Late Triassic - Earliest Jurassic. The authors document a comparable extensional tectonic-igneous event occurring during the Late Cretaceous (Early Gulfian; Cenomanian-Santonian) along the southern margin of the cratonic platform from Arkansas to Georgia

    Marjorie Courtenay-Latimer: Extracts from the Internet

    Get PDF
    “Courtenay-Latimer will forever be remembered because of the prehistoric fish, named Latimeria chalumnae in her honour, which was discovered in 1938. She was the curator of the [East London] Museum back then and recognised the significance of the find by the captain of the trawler Nerine, Hendrik Goosen.

    Stable resonances and signal propagation in a chaotic network of coupled units

    Full text link
    We apply the linear response theory developed in \cite{Ruelle} to analyze how a periodic signal of weak amplitude, superimposed upon a chaotic background, is transmitted in a network of non linearly interacting units. We numerically compute the complex susceptibility and show the existence of specific poles (stable resonances) corresponding to the response to perturbations transverse to the attractor. Contrary to the poles of correlation functions they depend on the pair emitting/receiving units. This dynamic differentiation, induced by non linearities, exhibits the different ability that units have to transmit a signal in this network.Comment: 10 pages, 3 figures, to appear in Phys. rev.

    The z=0.8596 Damped Lyman Alpha Absorbing Galaxy Toward PKS 0454+039

    Get PDF
    We present {\it Hubble Space Telescope} and ground--based data on the zabs=0.8596z_{abs}=0.8596 metal line absorption system along the line of sight to PKS 0454+0356. The system is a moderate redshift damped Lyman alpha system, with N(HI)=(5.7±0.3)×1020{\rm N(HI)}=(5.7\pm0.3)\times10^{20}~cm−2^{-2} as measured from the {\it Faint Object Spectrograph} spectrum. We also present ground--based images which we use to identify the galaxy which most probably gives rise to the damped system; the most likely candidate is relatively underluminous by QSO absorber standards (MB∼−19.0M_B \sim -19.0 for q0=0.5q_0=0.5 and H0=50H_0=50 \kms Mpc−1^{-1}), and lies ∼8.5h−1\sim 8.5h^{-1} kpc in projection from the QSO sightline. Ground--based measurements of Zn~II, Cr~II, and Fe~II absorption lines from this system allow us to infer abundances of [Zn/H]=−1.1-1.1, [Cr/H]=−1.2-1.2, and [Fe/H]=−1.2-1.2, indicating overall metallicity similar to damped systems at z>2z >2, and that the depletion of Cr and Fe onto dust grains may be even {\it less} important than in many of the high redshift systems of comparable metallicity. Limits previously placed on the 21-cm optical depth in the z=0.8596z=0.8596 system, together with our new N(H~I) measurement, suggest a very high spin temperature for the H~I, TS>>580T_S >> 580 K.Comment: changed uuencode header to produce .Z file so that unix uncompress command will work without modifying file nam

    Sea level ~400 000 years ago (MIS 11): analogue for present and future sea-level?

    Get PDF
    Comparison of the sea-level today with that of 400 000 years ago (MIS 11), when the Earth's orbital characteristics were similar may provide, under conditions of natural variability, indications of future sea-level during the present interglacial. Then, as now, orbital eccentricity was low and precession dampened. Evidence for MIS 11 sea-level occurs on uplifting coastlines where shorelines with geochronological ages have been preserved. The sea-level term and the uplift term may be separated with an "uplift correction" formula. This discovers the original sea-level at which the now uplifted shoreline was fashioned. Estimates are based on average uplift rates of the "last interglacial" sea-level (MIS 5.5) using a range of estimates for sea-level and age at that time at different locations. These, with varying secular tectonic regimes in different ocean basins, provide a band of estimates for the MIS 11 sea-level. They do not support the hypothesis of an MIS 11 sea-level at ~20 m, and instead show that it was closer to its present level

    Truman, Kennedy, and Reagan: Assessing the Impact of Assassination Attempts on the Organizational Culture of the U.S. Secret Service

    Get PDF
    The U.S. Secret Service (USSS), one of the most elite security agencies in the world, is charged with protecting the President of the United States at any cost. Three American presidents fell to assassins\u27 bullets before the USSS was assigned the role of presidential protection; one more would later be slain despite USSS protection. This study examines the organizational culture of the USSS, employing the methodology of cultural topography (CTOPS) to identify the agency\u27s norms, values, identity, and perceptual lens. We review three of the most impactful twentieth-century assassination attempts-two failed, one successful-and their formative effect on USSS organizational culture. Beginning with the lesser-known plot to assassinate Harry Truman, we examine the permanent authorization of the Presidential Protective Division. We apply our main focus to the assassination of John Kennedy, the USSS\u27s darkest hour and still its most powerful motivator. Lastly, we review the attack on Ronald Reagan and the development of the modern motivator. Lastly we review the attack on Ronald Reagan and the development of the modern USSS security apparatus. Our final profile of USSS organization culture gives insight into the agency\u27s strengths and weaknesses and highlights the emergent challenges of the 21st century
    • …
    corecore