7,187 research outputs found
Nicholas J. Contos, 1918.
No full textNicholas J. Contos, 1918. Mr. Contos was proprietor of Broadway Confectionery.Source: Booklet, "Winston-Salem, City of Industry," 1918
Dr. David Nicholas Dalton.
No full textDr. David Nicholas Dalton (1860-1928). Dr. Dalton was a physician in Winston-Salem.Photo made in the 1920s
Interview with Nicholas Christopher, author of Somewhere in the Night: Film Noir and the American City
No full textInterview with Nicholas Christopher, author of Somewhere in the Night: Film Noir and the American Cit
Using Ambient Seismic Noise to Determine Short Period Phase Velocities and Shallow Shear Velocities in Young Oceanic Lithosphere
No full textUsing 10 broadband ocean bottom seismometers from the 11-month-long deployment of the Gravity Lineations Intraplate Melting Petrologic and Seismologic Expedition (GLIMPSE) passive seismic experiment located in the south central Pacific, we have estimated the seismic impulse responses from ambient seismic noise for 45 station-to-station paths. The raw impulse responses show moveout with station-to-station distance, and there is a trend of decreasing signal-to-noise ratios as the station-to-station distance increases. The decrease in signal-to-noise ratio is expected as a smaller range of azimuths of propagating surface waves will contribute constructively to the cross-correlated signal with increasing distance, although scattering may also play a role in the coherence of seismic noise at periods less than 16 sec. From these station-to-station paths, we determined group velocities for the fundamental mode Rayleigh waves of a 2–16-sec period and the second mode Rayleigh wave of a 3.5–7-sec period. We calculate phase velocities for the fundamental mode and second mode Rayleigh wave over the same period range as the group velocities by applying a time variable filter to the noise correlation function and carefully unwrapping the phase spectrum of the resulting filtered impulse responses. Within this period range, there is a transition from waves at short periods, whose energy is mostly in the water column, to waves sensitive to crustal and upper mantle structure. The phase velocities for the second mode, which have peak sensitivity in the lower crust and shallow mantle, show evidence for azimuthal anisotropy. The average phase velocities of the station-to-station paths in the east–west direction are 2% faster than the north–south paths at the 4–7-sec period, consistent with the fast directions determined from SKS wave splitting measurements of N100°E. By incorporating the short-period fundamental and higher mode phase velocities from ambient seismic noise with longer period (16–100 sec) fundamental mode Rayleigh-wave phase velocities determined from teleseismic events, we inverted for the average crustal and upper mantle shear velocity structure and water column depth and velocity. The predicted phase velocities are extremely sensitive to the water column compressional velocity. We determined the average water column velocity to be 1466±3 m/sec, in contrast to the average of 1500 m/sec estimated from shipboard measurements weighted according to the Rayleigh-wave sensitivity kernel. The difference may be due to the dispersive effects of scattering by bathymetry or by the thin variable thickness sediment layer. The inversion also produces a Vp/Vs ratio of 1.88 for the crust. This method can provide useful information about the shallow seismic structure of the oceanic crust and uppermost mantle and is an important complement to longer period studies. <br/
Analysis of gravity and topography in the GLIMPSE study region: Isostatic compensation and uplift of the Sojourn and Hotu Matua Ridge systems
No full textThe Gravity Lineations Intraplate Melting Petrologic and Seismic Expedition (GLIMPSE) Experiment investigated the formation of a series of non–hot spot, intraplate volcanic ridges in the South Pacific and their relationship to cross-grain gravity lineaments detected by satellite altimetry. Using shipboard gravity measurements and a simple model of surface loading of a thin elastic plate, we estimate effective elastic thicknesses ranging from ?2 km beneath the Sojourn Ridge to a maximum of 10 km beneath the Southern Cross Seamount. These elastic thicknesses are lower than predicted for the 3–9 Ma seafloor on which the volcanoes lie, perhaps due to reheating and thinning of the plate during emplacement. Anomalously low apparent densities estimated for the Matua and Southern Cross seamounts of 2050 and 2250 kg m?3, respectively, probably are artifacts caused by the assumption of only surface loading, ignoring the presence of subsurface loading in the form of underplated crust and/or low-density mantle. Using satellite free-air gravity and shipboard bathymetry, we calculate the age-detrended, residual mantle Bouguer anomaly (rMBA). The rMBA corrects the free-air anomaly for the direct effects of topography, including the thickening of the crust beneath the seamounts and volcanic ridges due to surface loading of the volcanic edifices. There are broad, negative rMBA anomalies along the Sojourn and Brown ridges and the Hotu Matua seamount chain that extend nearly to the East Pacific Rise. These negative rMBA anomalies connect to negative free-air anomalies in the western part of the study area that have been recognized previously as the beginnings of the cross-grain gravity lineaments. Subtracting the topographic effects of surface loading by the ridges and seamounts from the observed topography reveals that the ridges are built on broad bands of anomalously elevated seafloor. This swell topography and the negative rMBA anomalies contradict the predictions of lithospheric cracking models for the origin of gravity lineaments and associated volcanic ridges, favoring models with a dynamic mantle component such as small-scale convection or channelized asthenospheric return flow. <br/
Resurrecting the Author
No full textPresentation of Nicholas Wolterstorff\u27s Paper Resurrecting the Author with time after for questions beginning at 18:00
Heritability and Linkage Analysis of Appendicitis Utilizing Age at Onset
No full textAppendicitis usually afflicts the young, but there is a large tail in the distribution of onset age. The genetics of this disease are still not well understood. A heritability analysis and genome wide linkage analysis of a large twin dataset was undertaken. Treating age of onset of appendicitis as a censored survival trait revealed a heritability of 0.21, and found evidence of linkage to Chromosome 1p37.3. Author(s): Christopher Oldmeadow 1 * | Kerrie Mengersen 2 | Nicholas Martin 3 | David L. Duffy
Thickening of young Pacific lithosphere from high-resolution Rayleigh wave tomography: A test of the conductive cooling model
No full textDirect seismic measurements of the thickening of oceanic lithosphere away from the spreading axis are rare due to the remoteness of mid ocean ridges. On the East Pacific Rise, at 17°S, there were two long-term broadband ocean bottom seismometer deployments, the MELT and GLIMPSE experiments. These arrays spanned young Pacific plate seafloor ranging in age from 0 to 8 Ma. Combining these two data sets, we describe the increase in Rayleigh wave phase velocities for 16–100 s period as function of distance from the ridge with two parameterizations: an arbitrary function of seafloor age and a simple polynomial function of age on the Pacific and Nazca plates. Although resolution analysis shows that 10 to 15 independent pieces of information about the age variation of phase velocity on the Pacific plate can be resolved at periods of ? 50 s, the three parameter polynomial model fits the data almost as well, indicating a simple pattern of the evolution of structure with age.To compare our observations to the predictions for the conductive cooling of the lithosphere, we convert a thermal half-space cooling model to shear velocity using anharmonic and anelastic contributions. The patterns in the velocities are not consistent with simple conductive cooling. The conductive cooling model under predicts the changes in phase velocity with age observed in the 20 to 78 s period range. We observe significant changes in shear velocity in the asthenosphere at depths greater than conductive cooling should extend. The asthenospheric low velocity zone is asymmetric, dipping to the west with the lowest velocities beneath the Pacific plate west of the spreading center. The conductive cooling model also over predicts the shear velocities in the lithosphere by ~ 0.2 km/s. These anomalies indicate that more complicated mantle flow and significant mantle heterogeneities such as melt are required.<br/
P and S Delays Beneath Intraplate Volcanic Ridges and Gravity Lineations Near the East Pacific Rise
No full textThe Gravity Lineations Intraplate Melting Petrology and Seismic Expedition (GLIMPSE) explored the origin of two intraplate, non–hot spot ridge systems associated with gravity lineations in the south central Pacific. Using the 11 month ocean bottom seismometer (OBS) deployment of the GLIMPSE experiment, we determined the average P and S station delays for the region. Across the array, station delays varied by 1.22 s for P waves and 2.13 s for S waves. The presence of ultraslow shear velocity (<400 m/s) sediment layers of variable thickness throughout the region introduced S delays, determined from P-to-S-converted phases generated at the crust-sediment boundary, of 0.08 to 0.43 s. Consequently, we corrected the S delays for these sediments to examine seismic anomalies due to crustal and mantle structure. We used the sediment delay times and the relative amplitudes of the converted phases to estimate the average regional shear velocity and thickness of the sediment layer beneath the stations. The range of sediment thickness in the region is 10–70 m, and the average shear velocity in the sediments is 140 m/s. Both the average P and sediment-corrected S delays show a positive correlation with seafloor age, with faster arrivals on older seafloor where the seismically fast lithosphere has thickened away from the spreading axis. The delay times also correlate with the residual mantle Bouguer gravity anomaly (rMBA), with slow arrivals coinciding with rMBA lows and the associated ridge systems. The delays are much too large to be caused by variations in crustal thickness and must represent anomalies within the mantle. These observations qualitatively support the either the channelized asthenospheric return flow model or the small-scale convection hypothesis for the origin of the gravity lineations. These models predict both positively correlated density and velocity anomalies caused by thermal anomalies and the pressure-release melting that migrates to the surface to form the volcanic ridges above the upwelling limbs of convection cells or channels. <br/
Nicholas de Monchaux: Local Code / Real Estates
No full textNicholas de Monchaux is an architect and urbanist whose work explores the intersections between nature, technology, and the city. He is the author of Spacesuit: Fashioning Apollo (MIT Press, 2011), an architectural history of the Apollo 11 spacesuit. He is Assistant Professor of Architecture and Urban Design at UC Berkeley. The work of his design studio has been exhibited widely and is currently being featured in the US Pavillion of the 13th Venice Biennale
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