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Sample records for african seismic experiment

  1. Active seismic experiment

    NASA Technical Reports Server (NTRS)

    Kovach, R. L.; Watkins, J. S.; Talwani, P.

    1972-01-01

    The Apollo 16 active seismic experiment (ASE) was designed to generate and monitor seismic waves for the study of the lunar near-surface structure. Several seismic energy sources are used: an astronaut-activated thumper device, a mortar package that contains rocket-launched grenades, and the impulse produced by the lunar module ascent. Analysis of some seismic signals recorded by the ASE has provided data concerning the near-surface structure at the Descartes landing site. Two compressional seismic velocities have so far been recognized in the seismic data. The deployment of the ASE is described, and the significant results obtained are discussed.

  2. Active Seismic Imaging Experiment

    NASA Astrophysics Data System (ADS)

    Berge, Patricia A.; Dawson, Phillip B.; Evans, John R.

    In September 1985 the U.S. Geological Survey (USGS) and Lawrence Livermore National Laboratory (LLNL) will conduct an active seismic experiment in the Medicine Lake area of northern California. The work is supported by the Geothermal Research Program of USGS and by the Geothermal and Hydropower Technologies Division of the U.S. Department of Energy. We invite interested organizations or individuals to record our explosions from Medicine Lake volcano and surrounding areas not covered by the USGS-LLNL array.

  3. Passive seismic experiment

    NASA Technical Reports Server (NTRS)

    Latham, G. V.; Ewing, M.; Press, F.; Sutton, G.; Dorman, J.; Nakamura, Y.; Toksoz, N.; Lammlein, D.; Duennebier, F.

    1972-01-01

    The establishment of a network of seismic stations on the lunar surface as a result of equipment installed by Apollo 12, 14, and 15 flights is described. Four major discoveries obtained by analyzing seismic data from the network are discussed. The use of the system to detect vibrations of the lunar surface and the use of the data to determine the internal structure, physical state, and tectonic activity of the moon are examined.

  4. Seismicity of the Earth 1900-2013 East African Rift

    USGS Publications Warehouse

    Hayes, Gavin P.; Jones, Eric S.; Stadler, Timothy J.; Barnhart, William D.; McNamara, Daniel E.; Benz, Harley M.; Furlong, Kevin P.; Villaseñor, Antonio

    2014-01-01

    Rifting in East Africa is not all coeval; volcanism and faulting have been an ongoing phenomenon on the continent since the Eocene (~45 Ma). The rifting began in northern East Africa, and led to the separation of the Nubia (Africa) and Arabia plates in the Red Sea and Gulf of Aden, and in the Lake Turkana area at the Kenya-Ethiopia border. A Paleogene mantle superplume beneath East Africa caused extension within the Nubia plate, as well as a first order topographic high known as the African superswell which now includes most of the eastern and southern sectors of the Nubia plate. Widespread volcanism erupted onto much of the rising plateau in Ethiopia during the Eocene-Oligocene (45–29 Ma), with chains of volcanoes forming along the rift separating Africa and Arabia. Since the initiation of rifting in northeastern Africa, the system has propagated over 3,000 km to the south and southwest, and it experiences seismicity as a direct result of the extension and active magmatism.

  5. Seismic Constraints on Geometry, Seismic Velocity and Anisotropy of the "African Anomaly"

    NASA Astrophysics Data System (ADS)

    Wang, Y.; Wen, L.

    2006-05-01

    Seismic evidence shows that the "African Anomaly", a prominent low-velocity structure in the lower mantle beneath Africa, has a broad base near the core-mantle boundary (CMB) and extends at least 1000 km upward into the mid-lower mantle. Waveform modeling results indicate that its base is a very-low velocity province (VLVP) in the lowermost 200-300 km of the Earth's mantle with rapidly varying geometries and a strong Vs reduction gradient of -2% - -12% from top to bottom. These features unambiguously indicate the VLVP is compositionally distinct and can be best explained by partial melting driven by a compositional change produced in the early Earth's history [Wen, 2001; Wen et. al, 2001; Wang and Wen, 2004]. Seismic structure for the mid-lower mantle portion of the "African Anomaly" and the anisotropic behavior related to the VLVP remain unclear. In this presentation, we will present seismic data to constrain geometry and both P- and S- velocity perturbations for the "African Anomaly" along the great arc from the East Pacific Rise to the Japan Sea, and discuss seismic anisotropic behavior inside the VLVP and in the surrounding areas. We collected direct S, ScS, SKS, and SKKS waveforms data sets for 9 earthquakes recorded at the temporary broadband Kaapvaal, Tanzania, and Ethiopia/Kenya seismic arrays in Africa. These seismic data provide reasonably good coverage for the "African Anomaly" along a great circle path in opposite directions. We corrected for the effects of the earthquake mislocation and the seismic heterogeneities outside the anomaly. Seismic data suggest that the "African Anomaly" exhibits a "cusp-like" shape along the great arc and continuously extends from the CMB to about 1300 km above the CMB with both sides tilting toward its center beneath southern Africa. The magnitude of these travel time residuals can be best explained by a shear velocity structure with average Vs reductions of -5% for the basal layer and -2% - -3% for the portion in the

  6. The Apollo passive seismic experiment

    NASA Technical Reports Server (NTRS)

    Latham, G. V.; Dorman, H. J.; Horvath, P.; Ibrahim, A. K.; Koyama, J.; Nakamura, Y.

    1979-01-01

    The completed data set obtained from the 4-station Apollo seismic network includes signals from approximately 11,800 events of various types. Four data sets for use by other investigators, through the NSSDC, are in preparation. Some refinement of the lunar model based on seismic data can be expected, but its gross features remain as presented two years ago. The existence of a small, molten core remains dependent upon the analysis of signals from a single, far-side impact. Analysis of secondary arrivals from other sources may eventually resolve this issue, as well as continued refinement of the magnetic field measurements. Evidence of considerable lateral heterogeneity within the moon continues to build. The mystery of the much meteoroid flux estimate derived from lunar seismic measurements, as compared with earth-based estimates, remains; although, significant correlations between terrestrial and lunar observations are beginning to emerge.

  7. Meteoroid flux from passive seismic experiment data

    NASA Technical Reports Server (NTRS)

    Duennebier, F.; Dorman, J.; Lammlein, D.; Latham, G.; Nakamura, Y.

    1975-01-01

    The meteoroid flux hitting the moon is recomputed using new information on the decrease of seismic signal amplitude with range. The new data are principally 17 large meteoroid impacts whose locations have been computed from recordings at all four of the operating Passive Seismic Experiment stations. These data suggest a rapid decrease in amplitudes beyond about 2200 km (chord range) which was not suspected earlier. The new estimate predicts the abundance of meteoroids with masses between 500 and 50,000 g. The result is considerably lower than estimates from earth-based observations, and close to our previous estimate from long-period lunar seismic data.

  8. Upper Mantle Seismic Structure Beneath Southern Africa: Constraints on the Buoyancy Supporting the African Superswell

    NASA Astrophysics Data System (ADS)

    Brandt, Martin B. C.; Grand, Stephen P.; Nyblade, Andrew A.; Dirks, Paul H. G. M.

    2012-04-01

    We present new one-dimensional SH-wave velocity models of the upper mantle beneath the Kalahari craton in southern Africa obtained from waveform inversion of regional seismograms from an Mw = 5.9 earthquake located near Lake Tanganyika recorded on broadband seismic stations deployed during the 1997-1999 Southern African Seismic Experiment. The velocity in the lithosphere beneath the Kalahari craton is similar to that of other shields, and there is little evidence for a significant low velocity zone beneath the lithosphere. The lower part of the lithosphere, from 110 to 220 km depth, is slightly slower than beneath other shields, possibly due to higher temperatures or a decrease in Mg number (Mg#). If the slower velocities are caused by a thermal anomaly, then slightly less than half of the unusually high elevation of the Kalahari craton can be explained by shallow buoyancy from a hot lithosphere. However, a decrease in the Mg# of the lower lithosphere would increase the density and counteract the buoyancy effect of the higher temperatures. We obtain a thickness of 250 ± 30 km for the mantle transition zone, which is similar to the global average, but the velocity gradient between the 410 and 660 km discontinuities is less steep than in global models, such as PREM and IASP91. We also obtain velocity jumps of between 0.16 ± 0.1 and 0.21 ± 0.1 km/s across the 410 km discontinuity. Our results suggest that there may be a thermal or chemical anomaly in the mantle transition zone, or alternatively that the shear wave velocity structure of the transition zone in global reference models needs to be refined. Overall, our seismic models provide little support for an upper mantle source of buoyancy for the unusually high elevation of the Kalahari craton, and hence the southern African portion of the African Superswell.

  9. Experiments on Seismic Metamaterials: Molding Surface Waves

    NASA Astrophysics Data System (ADS)

    Brûlé, S.; Javelaud, E. H.; Enoch, S.; Guenneau, S.

    2014-04-01

    Materials engineered at the micro- and nanometer scales have had a tremendous and lasting impact in photonics and phononics. At much larger scales, natural soils civil engineered at decimeter to meter scales may interact with seismic waves when the global properties of the medium are modified, or alternatively thanks to a seismic metamaterial constituted of a mesh of vertical empty inclusions bored in the initial soil. Here, we show the experimental results of a seismic test carried out using seismic waves generated by a monochromatic vibrocompaction probe. Measurements of the particles' velocities show a modification of the seismic energy distribution in the presence of the metamaterial in agreement with numerical simulations using an approximate plate model. For complex natural materials such as soils, this large-scale experiment was needed to show the practical feasibility of seismic metamaterials and to stress their importance for applications in civil engineering. We anticipate this experiment to be a starting point for smart devices for anthropic and natural vibrations.

  10. Experiments on seismic metamaterials: molding surface waves.

    PubMed

    Brûlé, S; Javelaud, E H; Enoch, S; Guenneau, S

    2014-04-01

    Materials engineered at the micro- and nanometer scales have had a tremendous and lasting impact in photonics and phononics. At much larger scales, natural soils civil engineered at decimeter to meter scales may interact with seismic waves when the global properties of the medium are modified, or alternatively thanks to a seismic metamaterial constituted of a mesh of vertical empty inclusions bored in the initial soil. Here, we show the experimental results of a seismic test carried out using seismic waves generated by a monochromatic vibrocompaction probe. Measurements of the particles' velocities show a modification of the seismic energy distribution in the presence of the metamaterial in agreement with numerical simulations using an approximate plate model. For complex natural materials such as soils, this large-scale experiment was needed to show the practical feasibility of seismic metamaterials and to stress their importance for applications in civil engineering. We anticipate this experiment to be a starting point for smart devices for anthropic and natural vibrations. PMID:24745420

  11. Apollo 14 active seismic experiment.

    PubMed

    Watkins, J S; Kovach, R L

    1972-03-17

    Explosion seismic refraction data indicate that the lunar near-surface rocks at the Apollo 14 site consist of a regolith 8.5 meters thick and characterized by a compressional wave velocity of 104 meters per second. The regolith is underlain by a layer with a compressional wave velocity of 299 meters per second. The thickness of this layer, which we interpret to be the Fra Mauro Formation, is between 16 and 76 meters. The layer immediately beneath this has a velocity greater than 370 meters per second. We found no evidence of permafrost. PMID:17794200

  12. Apollo 14 active seismic experiment.

    NASA Technical Reports Server (NTRS)

    Watkins, J. S.; Kovach, R. L.

    1972-01-01

    Explosion seismic refraction data indicate that the lunar near-surface rocks at the Apollo 14 site consist of a regolith 8.5 meters thick and characterized by a compressional wave velocity of 104 meters per second. The regolith is underlain by a layer with a compressional wave velocity of 299 meters per second. The thickness of this layer, which we interpret to be the Fra Mauro Formation, is between 16 and 76 meters. The layer immediately beneath this has a velocity greater than 370 meters per second. We found no evidence of permafrost.

  13. Cataloging the Pan-African Experience

    ERIC Educational Resources Information Center

    Hayes, Dianne

    2012-01-01

    Of all the honors and accolades bibliophile and noted authority on the Underground Railroad Charles Blockson has received, being bequeathed recently with some of Harriet Tubman's personal items by her great-niece is one of the most significant experiences of his life. A longtime collector of books and rare items by and about African-Americans,…

  14. Permafrost Active Layer Seismic Interferometry Experiment (PALSIE).

    SciTech Connect

    Abbott, Robert; Knox, Hunter Anne; James, Stephanie; Lee, Rebekah; Cole, Chris

    2016-01-01

    We present findings from a novel field experiment conducted at Poker Flat Research Range in Fairbanks, Alaska that was designed to monitor changes in active layer thickness in real time. Results are derived primarily from seismic data streaming from seven Nanometric Trillium Posthole seismometers directly buried in the upper section of the permafrost. The data were evaluated using two analysis methods: Horizontal to Vertical Spectral Ratio (HVSR) and ambient noise seismic interferometry. Results from the HVSR conclusively illustrated the method's effectiveness at determining the active layer's thickness with a single station. Investigations with the multi-station method (ambient noise seismic interferometry) are continuing at the University of Florida and have not yet conclusively determined active layer thickness changes. Further work continues with the Bureau of Land Management (BLM) to determine if the ground based measurements can constrain satellite imagery, which provide measurements on a much larger spatial scale.

  15. Lunar seismic profiling experiment natural activity study

    NASA Technical Reports Server (NTRS)

    Duennebier, F. K.

    1976-01-01

    The Lunar Seismic Experiment Natural Activity Study has provided a unique opportunity to study the high frequency (4-20 Hz) portion to the seismic spectrum on the moon. The data obtained from the LSPE was studied to evaluate the origin and importance of the process that generates thermal moonquakes and the characteristics of the seismic scattering zone at the lunar surface. The detection of thermal moonquakes by the LSPE array made it possible to locate the sources of many events and determine that they are definitely not generated by astronaut activities but are the result of a natural process on the moon. The propagation of seismic waves in the near-surface layers was studied in a qualitative manner. In the absence of an adequate theoretical model for the propagation of seismic waves in the moon, it is not possible to assign a depth for the scattering layer. The LSPE data does define several parameters which must be satisfied by any model developed in the future.

  16. The SEIS Experiment: A Mars Seismic Package

    NASA Technical Reports Server (NTRS)

    Schibler, P.; Lognonne, P.; Giardini, D.; Banerdt, B.; Karczewski, J. F.; Mimoun, D.; Zweifel, P.; Pike, T.; Ammann, J.; Anglade, A.

    2003-01-01

    This experiment will integrate a VBB (Very Broad Band) two axis seismometer, a three axis Short Period seismometer and a series of environmental sensors for pressure, infra-sounds and temperature. IPGP (France) has the overall responsibility of the experiment and is responsible for the VBB and environmental sensors. ETHZ (Switzerland) is responsible for the electronics of the experiment and JPL (USA) for the SP (Short Period) sensors. SEIS instrument was first proposed and accepted for NetLander mission (and will also be in charge of data acquisition for SPICE experiment). This seismic package should also be proposed for future missions.

  17. Seismic anisotropy across the east African plateau from shear wave splitting analysis

    NASA Astrophysics Data System (ADS)

    Bagley, B. C.; Nyblade, A.; Mulibo, G.; Tugume, F.

    2011-12-01

    Previous studies of the east African plateau reveal complicated patterns of seismic anisotropy that are not easily explained by a single mechanism. The pattern is defined by rift-parallel fast directions for stations within or near Cenozoic rift valleys, and near-null results in Precambrian terrains away from the rift. Data from 65 temporary Africa Array stations deployed between 2007 and 2011 are being used to make new shear wave splitting measurements. The stations span the east African plateau and cover both the eastern and western branches of the east African rift system, as well as unrifted Proterozoic and Archean terrains in Uganda, Kenya, Tanzania, and Zambia. Through analysis of shear wave splitting we will better constrain the distribution of seismic anisotropy, and and from it gain new insight into the tectonic evolution of east Africa.

  18. Experiences of African American adolescent fathers.

    PubMed

    Dallas, C M; Chen, S P

    1998-04-01

    Social and cultural factors influence the experience of fatherhood. This descriptive focus-group study describes the lived experience of fatherhood from the perspectives of 5 unmarried, low-income, African American adolescent fathers in a Midwestern urban area. Naturalistic inquiry approach guided the study. Seven themes of fatherhood emerged: barriers to fatherhood, value of fatherhood, introduction to fatherhood, competencies of fatherhood, role-set relationships, social norms of fatherhood, and father-child contact. This study suggests that nurses should support the involvement of adolescent fathers with their children. Future study may determine the influence of adult female family members on the decisions of adolescent fathers to remain involved with their children. PMID:9550932

  19. South African TOPEX/Poseidon altimeter experiment

    NASA Technical Reports Server (NTRS)

    Gruendlingh, Marten L.; Shannon, L. V.; Lutjeharms, J. R.

    1991-01-01

    The area surrounding the southern tip of Africa contains a juxtaposition of a variety of interesting and climatically relevant features. On the Indian Ocean side, the Agulhas Current with its tributaries form a conduit through which much of the southern Indian Ocean surface flow is focused. South of the continent, this flow is fragmented and partially injected into the Atlantic Ocean and across the Subtropical Convergence into the Southern Ocean. To the west of the subcontinent, the circulation of the South Atlantic subtropical gyre in the Cape Basin interacts with the vigorous Benguela upwelling regime. The creation, transformation, and transport of water masses and the intra-annual and climatic importance of all these processes have been specifically recognized by the World Ocean Circulation Experiment (WOCE). The South African TOPEX/POSEIDON Altimeter Experiment addresses many of these issues through four mutually complementary and interrelated subprojects.

  20. The college life experiences of African American women athletes.

    PubMed

    Sellers, R M; Kuperminc, G P; Damas, A

    1997-10-01

    The present study provides a descriptive analysis of four areas of African American women student athletes' college life experiences: academic performance; alienation and abuse; perceived social advantage as the result of athletics; and life satisfaction. Multivariate comparisons were made between the four areas of college life experiences of 154 African American women student athletes and 793 White women student athletes, 250 African American women nonathletes, and 628 African American men student athletes from a national sample of 39 NCAA Division I universities. Overall, African American women student athletes are performing adequately academically, integrating socially within the university, perceiving some social advantage as the result of being athletes, and are fairly satisfied with their life. Their experiences seem most consistent with African American women nonathletes. Results are discussed in the context of potential policy recommendations as well as the need for more research on this particular population. PMID:9485580

  1. Seismic-while-drilling data processing with seismic interferometry in the Daqing Oilfield experiment

    NASA Astrophysics Data System (ADS)

    Liu, Hongtao 1Huang, Weichuan 24Li, Yuquan

    2014-03-01

    Seismic interferometry was used to process the data collected with seismic-while-drilling (SWD) experiments at the Daqing Oilfield. The experiments simultaneously recorded the data at the drilling stem and on the ground. After conducting the frequency and the energy property analysis, the data was processed using the correlation and deconvolution method. Seismic data was then obtained from excitation of the drill bit. The result maps show that the deconvolution method can suppress the source effects and enhance the resolution of the profile, and that the vertical stacks enhance the seismic response of the subsurface. The interferometry process after band-filtering can obtain maps with very high resolution. Seismic interferometry by deconvolution shows great advantages based on the results of this experimental data. The method can also be applied to the SWD data and the ambient seismic data to obtain better processing results.

  2. Teaching Experiences of African American Educators in the Rural South

    ERIC Educational Resources Information Center

    Polidore, Ellene; Edmonson, Stacey L.; Slate, John R.

    2010-01-01

    A scarcity of research exists regarding the voices of African American teachers who taught in the rural South. In this study, we report the life experiences, perceptions, thoughts, and feelings of three female African American educators as they pertain to their experiences teaching before, during, and after desegregation. Three female African…

  3. Upper mantle structure beneath southern African cratons from seismic finite-frequency P- and S-body wave tomography

    NASA Astrophysics Data System (ADS)

    Youssof, M.; Thybo, H.; Artemieva, I. M.; Levander, A.

    2015-06-01

    We present a 3D high-resolution seismic model of the southern African cratonic region from teleseismic tomographic inversion of the P- and S-body wave dataset recorded by the Southern African Seismic Experiment (SASE). Utilizing 3D sensitivity kernels, we invert traveltime residuals of teleseismic body waves to calculate velocity anomalies in the upper mantle down to a 700 km depth with respect to the ak135 reference model. Various resolution tests allow evaluation of the extent of smearing effects and help defining the optimum inversion parameters (i.e., damping and smoothness) for regularizing the inversion calculations. The fast lithospheric keels of the Kaapvaal and Zimbabwe cratons reach depths of 300-350 km and 200-250 km, respectively. The paleo-orogenic Limpopo Belt is represented by negative velocity perturbations down to a depth of ˜ 250 km, implying the presence of chemically fertile material with anomalously low wave speeds. The Bushveld Complex has low velocity down to ˜ 150 km, which is attributed to chemical modification of the cratonic mantle. In the present model, the finite-frequency sensitivity kernels allow to resolve relatively small-scale anomalies, such as the Colesberg Magnetic Lineament in the suture zone between the eastern and western blocks of the Kaapvaal Craton, and a small northern block of the Kaapvaal Craton, located between the Limpopo Belt and the Bushveld Complex.

  4. Cancer and the African American Experience

    Cancer.gov

    The first plenary of the EPEC-O (Education in Palliative and End-of-Life Care for Oncology) Self-Study: Cultural Considerations When Caring for African Americans explores the many factors that lead to inequalities in cancer care outcomes for African Americans.

  5. Observational studies in South African mines to mitigate seismic risks: implications for mine safety and tectonic earthquakes

    NASA Astrophysics Data System (ADS)

    Durrheim, Raymond; Ogaswara, Hiroshi; Nakatani, Masao; Yabe, Yasuo; Milev, Alexander; Cichowicz, Artur; Kawakata, Hironori; Moriya, Hirokazu; Naoi, Makoto; Kgarume, Thabang; Murakami, Osamu; Mngadi, Siyanda

    2014-05-01

    Seismicity poses a significant risk to workers in deep and overstressed mines, such as the gold mines in the Witwatersrand basin of South Africa, as well as inhabitants of earthquake-prone regions such as Japan. A 5-year collaborative project entitled "Observational studies in South African mines to mitigate seismic risks" was launched in 2010 to address these risks, drawing on over a century of South African and Japanese research experience with respect to mining-related and tectonic earthquakes, respectively. The project has three main aims: (1) to learn more about earthquake preparation and triggering mechanisms by deploying arrays of sensitive sensors within rock volumes where mining is likely to induce seismic activity; (2) to learn more about earthquake rupture and rockburst damage phenomena by deploying robust strong ground motion sensors close to potential fault zones and on stope hangingwalls; and (3) to upgrade the South African surface national seismic network in the mining districts. Research sites have been established at mines operated by Sibanye Gold (Hlanganani Shaft and Cooke #4 Shaft) and Anglogold Ashanti (Moab-Khotsong). More than 70 boreholes (totalling more than 2.8 km in length) have been drilled to locate "capable" faults i.e. faults that are considered likely to become seismically active as a result of mining activity and to deploy sensors. Acoustic emission sensors, strain- and tilt meters, and controlled seismic sources were installed to monitor the deformation of the rock mass, the accumulation of damage during the earthquake preparation phase, and changes in dynamic stress produced by the propagation of the rupture front. These data are being integrated with measurements of rock properties, stope closure, stope strong motion, seismic data recorded by the mine-wide network, and stress modelling. The mid-point of the 5-year project has passed. New observations of stress and the response of the rock mass to mining have already been made

  6. Seismic Anisotropy beneath the African Plate using Shear Wave Splitting Measurements from AfricaArray Stations

    NASA Astrophysics Data System (ADS)

    Nunley, M. E.; Weeraratne, D.; Nyblade, A.

    2011-12-01

    The African continental plate is made up of a series of cratons and fold belts with activation ages ranging from present to Archean. Recent studies have shown that this tectonic assemblage occurred over a long history of accretion and rifting cycles that likely left behind the complex crust and lithospheric fabric that we see today. Here we study seismic anisotropy beneath the African continent using a large array of permanent AfricaArray and Global Seismic Network seismic stations located throughout Africa. We supply shear wave splitting techniques to teleseismic earthquake events using the eigenvalue method where the second eigenvalue is minimized to determine anisotropy. Stations located in the Ethiopian rift zone yield a NE-SW fast direction with the largest delay times of 1.5s. One station (KOWA) located in the west African craton displays a NW-SE fast direction. Stations located near Cameroon, at the coastal edge of the central African shear zone, produce NW-SE fast directions oriented perpendicular to the shear zone axis. . A group of stations located on Archean crust in central Africa skirt the Congo craton and display consistent NNE fast directions and delay times of 1.0s. Two stations, LSZ and TEZI are located in the Damara suture belt between the Congo and Kaapvaal cratons display a NE-SW fast direction parallel to the suture axis. In the Kaapvaal craton region the average anisotropic direction is NNE with a 1.0s delay time. New stations available south of the Kaapvaal craton reveal a NE fast direction with delay times that vary from 0.5 to 1.3 s. Several splitting measurements are made for the southern station HVD which display backazimuth dependence producing NW-SE fast directions for ray paths coming from the east and are consistent with observations at GRM located east of HVD. These results show that seismic anisotropy across the continent is not uniform and shows significant variation between tectonic regions. While mantle flow and lithospheric

  7. Shallow lunar structure determined from the passive seismic experiment

    NASA Technical Reports Server (NTRS)

    Nakamura, Y.; Dorman, J.; Duennebier, F.; Lammlein, D.; Latham, G.

    1975-01-01

    Data relevant to the shallow structure of the moon obtained at the Apollo seismic stations are compared with previously published results of the active seismic experiments. It is concluded that the lunar surface is covered by a layer of low seismic velocity which appears to be equivalent to the lunar regolith defined previously by geological observations. This layer is underlain by a zone of distinctly higher seismic velocity at all of the Apollo landing sites. The regolith thicknesses at the Apollo 11, 12, and 15 sites are estimated from the shear-wave resonance to be 4.4, 3.7, and 4.4 m, respectively. These thicknesses and those determined at the other Apollo sites by the active seismic experiments appear to be correlated with the age determinations and the abundances of extralunar components at the sites.

  8. Mammoth Mountain, California broadband seismic experiment

    NASA Astrophysics Data System (ADS)

    Dawson, P. B.; Pitt, A. M.; Wilkinson, S. K.; Chouet, B. A.; Hill, D. P.; Mangan, M.; Prejean, S. G.; Read, C.; Shelly, D. R.

    2013-12-01

    Mammoth Mountain is a young cumulo-volcano located on the southwest rim of Long Valley caldera, California. Current volcanic processes beneath Mammoth Mountain are manifested in a wide range of seismic signals, including swarms of shallow volcano-tectonic earthquakes, upper and mid-crustal long-period earthquakes, swarms of brittle-failure earthquakes in the lower crust, and shallow (3-km depth) very-long-period earthquakes. Diffuse emissions of C02 began after a magmatic dike injection beneath the volcano in 1989, and continue to present time. These indications of volcanic unrest drive an extensive monitoring effort of the volcano by the USGS Volcano Hazards Program. As part of this effort, eleven broadband seismometers were deployed on Mammoth Mountain in November 2011. This temporary deployment is expected to run through the fall of 2013. These stations supplement the local short-period and broadband seismic stations of the Northern California Seismic Network (NCSN) and provide a combined network of eighteen broadband stations operating within 4 km of the summit of Mammoth Mountain. Data from the temporary stations are not available in real-time, requiring the merging of the data from the temporary and permanent networks, timing of phases, and relocation of seismic events to be accomplished outside of the standard NCSN processing scheme. The timing of phases is accomplished through an interactive Java-based phase-picking routine, and the relocation of seismicity is achieved using the probabilistic non-linear software package NonLinLoc, distributed under the GNU General Public License by Alomax Scientific. Several swarms of shallow volcano-tectonic earthquakes, spasmodic bursts of high-frequency earthquakes, a few long-period events located within or below the edifice of Mammoth Mountain and numerous mid-crustal long-period events have been recorded by the network. To date, about 900 of the ~2400 events occurring beneath Mammoth Mountain since November 2011 have

  9. 2013 East Bay Seismic Experiment (EBSE): implosion data, Hayward, Calif

    USGS Publications Warehouse

    Catchings, Rufus D.; Strayer, Luther M.; Goldman, Mark R.; Criley, Coyn J.; Garcia, Susan; Sickler, Robert R.; Catchings, Marisol K.; Chan, Joanne; Gordon, Leslie C.; Haefner, Scott; Blair, James Luke; Gandhok, Gini; Johnson, Michaela R.

    2015-01-01

    In August 2013, the California State University, East Bay (CSUEB) in Hayward, California imploded a 13-story building (Warren Hall) that was deemed unsafe because of its immediate proximity to the active trace of the Hayward Fault. The U.S. Geological Survey (USGS) and the CSUEB collaborated on a program to record the seismic waves generated by the collapse of the building. We refer to this collaboration as the East Bay Seismic Experiment (EBSE). The principal objective of recording the seismic energy was to observe ground shaking as it radiated from the source, but the data also may be useful for other purposes. For example, the seismic data may be useful in evaluating the implosion process as it relates to structural engineering purposes. This report provides the metadata needed to utilize the seismic data.

  10. Mother Tongue Education: The West African Experience.

    ERIC Educational Resources Information Center

    Bamgbose, Ayo, Ed.

    In the rapidly changing political, economic, and social life of West Africa, there is a renewed interest in cultural identity. This book describes the developments and the difficulties experienced by different West African countries in the use of mother tongues in multi-lingual society. The book was commissioned to give scholars, educators, and…

  11. The Mars SEIS Experiment: A Mars Seismic Package

    NASA Technical Reports Server (NTRS)

    Mimoun, D.; Lognonne, P.; Banerdt, W. B.; Schibler, P.; Giardini, D.; Pont, G.

    2005-01-01

    The Mars SEIS experiment. The SEIS experiment was first proposed by IPGP (and accepted) for the NetLander mission. It integrates two VBB (Very Broad Band) seismometers, a three axis Short Period seismometer and a series of environmental sensors for pressure, infra-sounds and temperature. IPGP (France) has the overall responsibility of the experiment and is responsible for the seismic and environmental sensors. ETHZ (Switzerland) is responsible for the electronics of the experiment and JPL (USA) for the SP (Short Period) sensors. As NetLander mission has been cancelled (while fortunately the development still goes on), this seismic package can be proposed for future Mars missions.

  12. African American Women's Breastfeeding Experiences: Cultural, Personal, and Political Voices.

    PubMed

    Spencer, Becky; Wambach, Karen; Domain, Elaine Williams

    2015-07-01

    The low rate of breastfeeding among African American women in the United States is a poorly understood, persistent disparity. Our purpose in this study was to gain an understanding of how African American women experience breastfeeding in the context of their day-to-day lives. The Sequential-Consensual Qualitative Design (SCQD), a 3-stage qualitative methodology aimed at exploring the cultural, personal, and political context of phenomena, was used to explore the experiences of African American women who felt successful with breastfeeding. An integration of qualitative content analysis and Black feminist theory was used to analyze the data. Themes that emerged from Stage-2 data analysis included self-determination, spirituality and breastfeeding, and empowerment. In Stage 3 of the study, participant recommendations regarding breastfeeding promotion and support initiatives for African American breastfeeding were categorized into three themes, including engaging spheres of influence, sparking breastfeeding activism, and addressing images of the sexual breast vs. the nurturing breast. PMID:25288408

  13. Results from the Apollo passive seismic experiment

    NASA Technical Reports Server (NTRS)

    Latham, G.; Nakamura, Y.; Dorman, J.; Duennebier, F.; Ewing, M.; Lammlein, D.

    1977-01-01

    Recent results from the Apollo Seismic Network suggest that primitive differentiation occurred in the outer shell of the moon to a depth of approximately 300 km and the central region of the moon is presently molten to a radius of between 200 and 300 km. If early melting to a depth of 300 to 400 km was a consequence of accretional energy, very short accretion times are required. It was shown that the best model for the zone of original differentiation is a crust 40 to 80 km thick, ranging in composition from anorthositic gabbro to gabbro, and overlying an ultramafic cumulate about 250 km thick. The best candidate for the molten core appears to be iron or iron sulphide. A new class of seismic signals recently were identified that may correspond to shallow moonquakes. These are rare, but much more energetic than the more numerous, deep moonquakes.

  14. Results from the Apollo passive seismic experiment

    NASA Technical Reports Server (NTRS)

    Lathum, G.; Nakamura, Y.; Dorman, J.; Duennebier, F.; Ewing, M.; Lammlein, D.

    1974-01-01

    Recent results from the Apollo seismic network suggest that primitive differentiation occurred in the outer shell of the moon to a depth of approximately 300 km; and the central region of the moon is presently molten to a radius of between 200 and 300 km. If early melting to a depth of 300 to 400 km was a consequence of accretional energy, very short accretion times are required. The best model for the zone of original differentiation appears to be a crust 40 to 80 km thick, ranging in composition from anorthositic gabbro to gabbro; overlying an ultramafic cumulate (olivine-pyroxene) about 250 km thick. The best candidate for the molten core appears to be iron or iron sulphide. A new class of seismic signals has recently been identified that may correspond to shallow moonquakes. These are rare, but much more energetic than the more numerous, deep moonquakes.

  15. Participation in the Apollo passive seismic experiment

    NASA Technical Reports Server (NTRS)

    Press, F.; Toksoez, M. N.; Dainty, A.

    1972-01-01

    Computer programs which were written to read digital tapes containing lunar seismic data were studied. Interpreting very early parts of the lunar seismogram as seismic body-wave phases enabled the determination of the structure of the outer part of the moon in the Fra Mauro region. The crust in the Fra Mauro region is 60 to 65 km-thick, overlaying a high velocity mantle. The crust is further divided into an upper part, 25 km thick, apparently made of material similar to the surficial basalts, and a lower part of seemingly different composition, possibly an anorthositic gabbro. The generation of the exceedingly long reverberating wave-train observed in lunar seismogram was also studied. This is believed to be due to an intense scattering layer with very high quality coefficient overlying a more homogeneous elastic medium. Titles and abstracts of related published papers are included.

  16. Explosives for Lunar Seismic Profiling Experiment (LSPE)

    NASA Technical Reports Server (NTRS)

    1973-01-01

    Explosive charges of various sizes were investigated for use in lunar seismic studies. Program logistics, and the specifications for procurement of bulk explosives are described. The differential analysis, thermal properties, and detonation velocity measurements on HNS/Teflon 7C 90/10 are reported along with the field tests of the hardware. It is concluded that nearly all large explosive charges crack after fabrication, from aging or thermal shock. The cracks do not affect the safety, or reliability of the explosives.

  17. The Lusi seismic experiment: An initial study to understand the effect of seismic activity to Lusi

    NASA Astrophysics Data System (ADS)

    Karyono, Mazzini, Adriano; Lupi, Matteo; Syafri, Ildrem; Masturyono, Rudiyanto, Ariska; Pranata, Bayu; Muzli, Widodo, Handi Sulistyo; Sudrajat, Ajat; Sugiharto, Anton

    2015-04-01

    The spectacular Lumpur Sidoarjo (Lusi) eruption started in northeast Java on the 29 of May 2006 following a M6.3 earthquake striking the island [1,2]. Initially, several gas and mud eruption sites appeared along the reactivated strike-slip Watukosek fault system [3] and within weeks several villages were submerged by boiling mud. The most prominent eruption site was named Lusi. The Lusi seismic experiment is a project aims to begin a detailed study of seismicity around the Lusi area. In this initial phase we deploy 30 seismometers strategically distributed in the area around Lusi and along the Watukosek fault zone that stretches between Lusi and the Arjuno Welirang (AW) complex. The purpose of the initial monitoring is to conduct a preliminary seismic campaign aiming to identify the occurrence and the location of local seismic events in east Java particularly beneath Lusi.This network will locate small event that may not be captured by the existing BMKG network. It will be crucial to design the second phase of the seismic experiment that will consist of a local earthquake tomography of the Lusi-AW region and spatial and temporal variations of vp/vs ratios. The goal of this study is to understand how the seismicity occurring along the Sunda subduction zone affects to the behavior of the Lusi eruption. Our study will also provide a large dataset for a qualitative analysis of earthquake triggering studies, earthquake-volcano and earthquake-earthquake interactions. In this study, we will extract Green's functions from ambient seismic noise data in order to image the shallow subsurface structure beneath LUSI area. The waveform cross-correlation technique will be apply to all of recordings of ambient seismic noise at 30 seismographic stations around the LUSI area. We use the dispersive behaviour of the retrieved Rayleigh waves to infer velocity structures in the shallow subsurface.

  18. The Lusi seismic experiment: An initial study to understand the effect of seismic activity to Lusi

    SciTech Connect

    Karyono; Mazzini, Adriano; Sugiharto, Anton; Lupi, Matteo; Syafri, Ildrem; Masturyono,; Rudiyanto, Ariska; Pranata, Bayu; Muzli,; Widodo, Handi Sulistyo; Sudrajat, Ajat

    2015-04-24

    The spectacular Lumpur Sidoarjo (Lusi) eruption started in northeast Java on the 29 of May 2006 following a M6.3 earthquake striking the island [1,2]. Initially, several gas and mud eruption sites appeared along the reactivated strike-slip Watukosek fault system [3] and within weeks several villages were submerged by boiling mud. The most prominent eruption site was named Lusi. The Lusi seismic experiment is a project aims to begin a detailed study of seismicity around the Lusi area. In this initial phase we deploy 30 seismometers strategically distributed in the area around Lusi and along the Watukosek fault zone that stretches between Lusi and the Arjuno Welirang (AW) complex. The purpose of the initial monitoring is to conduct a preliminary seismic campaign aiming to identify the occurrence and the location of local seismic events in east Java particularly beneath Lusi.This network will locate small event that may not be captured by the existing BMKG network. It will be crucial to design the second phase of the seismic experiment that will consist of a local earthquake tomography of the Lusi-AW region and spatial and temporal variations of vp/vs ratios. The goal of this study is to understand how the seismicity occurring along the Sunda subduction zone affects to the behavior of the Lusi eruption. Our study will also provide a large dataset for a qualitative analysis of earthquake triggering studies, earthquake-volcano and earthquake-earthquake interactions. In this study, we will extract Green’s functions from ambient seismic noise data in order to image the shallow subsurface structure beneath LUSI area. The waveform cross-correlation technique will be apply to all of recordings of ambient seismic noise at 30 seismographic stations around the LUSI area. We use the dispersive behaviour of the retrieved Rayleigh waves to infer velocity structures in the shallow subsurface.

  19. Experiences of undergraduate African health sciences students: A hermeneutic inquiry.

    PubMed

    Inyama, Davis; Williams, Allison; McCauley, Kay

    2015-06-01

    While efforts have been made to understand the experiences of African students in predominantly white environments, the experiences of African students in clinical placement areas have rarely been explored. This paper is a report on a study designed to address the gap in educational research on the experiences of African health sciences students in clinical placements in predominantly white environments. Interviews adopting an open approach to conversations were conducted with nine African students from three health disciplines at one metropolitan university in Australia between 2012 and 2013. Interview transcripts were analyzed using philosophical hermeneutics, where shared meanings were arrived at by employing key Gadamerian hermeneutic components. Findings revealed a number of factors that had a direct effect on the meaning students derived from their clinical placement experiences. These, as revealed in the interlinked domains of body, space, relationships, and time included difference, acceptance, resilience, and cultural sensitivity. Insights from this study may lead to the adoption of strategies designed to improve the experiences of African students studying health sciences in predominantly white environments. PMID:24942056

  20. Third Party Borehole Seismic Experiments During the Ocean Drilling Program

    NASA Astrophysics Data System (ADS)

    Swift, S. A.; Stephen, R. A.; Hoskins, H.; Bolmer, T.

    2003-12-01

    Third party borehole seismic experiments on the Ocean Drilling Program began with an oblique seismic experiment on Leg 102 at Site 418 in the Western Atlantic. Upper ocean crust here is characterized by a normal seismic layer 2 vertical velocity gradient, lateral velocity variations, azimuthal anisotropy, and azimuth dependent scattering. A normal incidence VSP was run on Leg 118 in the gabbro sequence at Hole 735B on the Southwest Indian Ridge. The vertical seismic velocity inferred from arrival times is similar to that observed horizontally by refraction in ocean layer 3, but attenuation is anomalously high, which prompted the hypothesis that the gabbro cored may not actually represent the bulk of Layer 3 material. The VSP data acquired at Hole 504B in the eastern equatorial Pacific on Legs 111 and 148 helped to constrain the P and S velocity structure at the site and showed that upper layer 3 at this site, at a depth of over 2 km into the crust, consisted of the lower portion of the sheeted dikes rather than gabbro. Both offset and normal incidence VSPs were run on Leg 164 to study the seismic velocity structure of gas hydrates on the Blake Ridge. A new innovation on ODP was the deployment of broadband seismometers in boreholes. Whereas the conventional VSPs and offset VSPs mentioned above operate in the frequency range from 1 to 100Hz, broadband seismometers are used in earthquake seismology and operate in the range from 0.001 to 10Hz. The first broadband seismometer test was carried out from the drill ship on Leg 128 in the Japan Sea. Subsequently 4 permanent broadband borehole seismic observatories were installed in the Western Pacific and Japan Trench on Legs 186, 191 and 195. The ODP era also saw the development of systems for re-entering boreholes from conventional research vessels after the drill ship left the site. Borehole seismic experiments and installations that used this wireline re-entry technology were carried out in DSDP Holes 534 (Blake

  1. Small Arrays for Seismic Intruder Detections: A Simulation Based Experiment

    NASA Astrophysics Data System (ADS)

    Pitarka, A.

    2014-12-01

    Seismic sensors such as geophones and fiber optic have been increasingly recognized as promising technologies for intelligence surveillance, including intruder detection and perimeter defense systems. Geophone arrays have the capability to provide cost effective intruder detection in protecting assets with large perimeters. A seismic intruder detection system uses one or multiple arrays of geophones design to record seismic signals from footsteps and ground vehicles. Using a series of real-time signal processing algorithms the system detects, classify and monitors the intruder's movement. We have carried out numerical experiments to demonstrate the capability of a seismic array to detect moving targets that generate seismic signals. The seismic source is modeled as a vertical force acting on the ground that generates continuous impulsive seismic signals with different predominant frequencies. Frequency-wave number analysis of the synthetic array data was used to demonstrate the array's capability at accurately determining intruder's movement direction. The performance of the array was also analyzed in detecting two or more objects moving at the same time. One of the drawbacks of using a single array system is its inefficiency at detecting seismic signals deflected by large underground objects. We will show simulation results of the effect of an underground concrete block at shielding the seismic signal coming from an intruder. Based on simulations we found that multiple small arrays can greatly improve the system's detection capability in the presence of underground structures. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344

  2. Bighorns Arch Seismic Experiment (BASE): Amplitude Response to Different Seismic Charge Configurations

    SciTech Connect

    Harder, S. H., Killer, K. C., Worthington, L. L., Snelson, C. M.

    2010-09-02

    Contrary to popular belief, charge weight is not the most important engineering parameter determining the seismic amplitudes generated by a shot. The scientific literature has long claimed that the relationship, A ~R2L1/2, where A is the seismic amplitude generated by a shot, R is the radius of the seismic charge and L is the length of that charge, holds. Assuming the coupling to the formation and the pressure generated by the explosive are constants, this relationship implies that the one should be able to increase the charge radius while decreasing the charge length and obtain more seismic amplitude with less charge weight. This has significant implications for the economics of lithospheric seismic shots, because shallower holes and small charge sizes decrease cost. During the Bighorns Array Seismic Experiment (BASE) conducted in the summer of 2010, 24 shots with charge sizes ranging from 110 to 900 kg and drill hole diameters of 300 and 450 mm were detonated and recorded by an array of up to 2000 single-channel Texan seismographs. Maximum source-receiver offset of 300 km. Five of these shots were located within a one-acre square in an effort to eliminate coupling effects due to differing geological formations. We present a quantitative comparison of the data from these five shots to experimentally test the equation above.

  3. An active seismic experiment proposal onboard the NASA 2009 MSL

    NASA Astrophysics Data System (ADS)

    Lognonné, P.; Experiment Team

    NASA will launch in 2009 a 900 kg class rover to Mars. This rover will land with a new descent system, called the ``sky-crane''. After releasing the rover on the ground, the sky-crane will have a final flight until a hard landing about 2 km away from the rover. The science objectives of the 2009 MSL mission, among others, are to characterize the geology of the landing region at all appropriate spatial scales, to interpret the processes that have formed and modified rocks and regolith and to determine present state, distribution, and cycling of water. We propose to perform with the sky-crane an active seismic experiment for subsurface characterization. This experiment will be conducted after the rover deployment. The proposed idea is to deploy a seismic receiver line by ejecting about 10 seismic nodes from the sky-crane and then to record then the reflected signals from the impact of the sky-crane. Preliminary modeling and tests indicate that a penetration depth of several hundred meters will be reached. The experiment will be used to determine a 2D geological profile of the landing site subsurface, to determine the depth and shape of the dry regolith/icy regolith discontinuity and to identify possible layering structures in the subsurface. In addition, information on the structure of the regolith (mean size of building blocs) and on the presence of liquid water will be obtained by an analysis of the seismic coda and attenuation. The seismic high frequency noise will also be monitored, especially during windy periods, and will be used to get additional information on the subsurface. The proposed experiment is based on a consortium between academics laboratories and seismic industry and will be a first example of a resource oriented experiment on another planet than Earth. The complete mass of the experiment will be 2.5 kg. Seismic nodes will have their own acquisition/power and telemetry system and will be based on high sensitive geophones developed for seismic

  4. The LUSI Seismic Experiment: Deployment of a Seismic Network around LUSI, East Java, Indonesia

    NASA Astrophysics Data System (ADS)

    Karyono, Karyono; Mazzini, Adriano; Lupi, Matteo; Syafri, Ildrem; Haryanto, Iyan; Masturyono, Masturyono; Hadi, Soffian; Rohadi, Suprianto; Suardi, Iman; Rudiyanto, Ariska; Pranata, Bayu

    2015-04-01

    The spectacular Lusi eruption started in northeast Java, Indonesia the 29 of May 2006 following a M6.3 earthquake striking the island. Initially, several gas and mud eruption sites appeared along the reactivated strike-slip Watukosek fault system and within weeks several villages were submerged by boiling mud. The most prominent eruption site was named Lusi. Lusi is located few kilometres to the NE of the Arjuno-Welirang volcanic complex. Lusi sits upon the Watukosek fault system. From this volcanic complex originates the Watukosek fault system that was reactivated by the M6.3 earthquake in 2006 and is still periodically reactivated by the frequent seismicity. To date Lusi is still active and erupting gas, water, mud and clasts. Gas and water data show that the Lusi plumbing system is connected with the neighbouring Arjuno-Welirang volcanic complex. This makes the Lusi eruption a "sedimentary hosted geothermal system". To verify and characterise the occurrence of seismic activity and how this perturbs the connected Watukosek fault, the Arjuno-Welirang volcanic system and the ongoing Lusi eruption, we deployed 30 seismic stations (short-period and broadband) in this region of the East Java basin. The seismic stations are more densely distributed around LUSI and the Watukosek fault zone that stretches between Lusi and the Arjuno Welirang (AW) complex. Fewer stations are positioned around the volcanic arc. Our study sheds light on the seismic activity along the Watukosek fault system and describes the waveforms associated to the geysering activity of Lusi. The initial network aims to locate small event that may not be captured by the Indonesian Agency for Meteorology, Climatology and Geophysics (BMKG) seismic network and it will be crucial to design the second phase of the seismic experiment that will consist of a local earthquake tomography of the Lusi-Arjuno Welirang region and temporal variations of vp/vs ratios. Such variations will then be ideally related to

  5. Seismic experiments, nuclear dismantlement go hand in hand in Kazakhstan

    NASA Astrophysics Data System (ADS)

    Leith, William; Kluchko, Luke J.

    Unique seismic experiments involving large chemical explosions at different depths have been conducted in Kazakhstan, thanks to nuclear dismantlement activity there. Collaborative efforts of several bodies have provided this creative, cost-efficient extension of the dismantling work, improving technical monitoring and verification of the Comprehensive Test Ban Treaty (CTBT).For the past several years, the Defense Special Weapons Agency (DSWA) has been closing the nuclear test tunnels and bore-holes at the former Soviet nuclear test site nearSemipalatinsk, eastern Kazakhstan, as part of the Nunn-Lugar Cooperative Threat Reduction (CTR) Program. The existence of this program and the infrastructure that was in place to implement it made it possible to conduct the seismic experiments. As a result, benchmark data have been collected on the variations in seismic signals from explosions at different burial depths.

  6. Near-field monitoring of seismic source behavior at South African deep gold mines

    NASA Astrophysics Data System (ADS)

    Ogasawara, H.; Nakatani, M.; Iio, Y.; Ishii, H.; Yamada, T.; Naoi, M.; Yasutake, G.; Kawakata, H.; Yamamoto, A.; Yamauchi, T.; Nakao, S.; Yabe, Y.; Otsuki, K.; Satoh, T.; Kato, A.; Shinya, Y.; Nagata, K.; Kuwano, O.; Igarashi, T.; Miyake, H.; Ide, S.; van Aswegen, G.; Mendecki, A.; Ward, T.; SeeSA Research Group

    2007-12-01

    We introduce our SeeSA projects, as important as dense array monitoring According to a mining plan and a geological map detailing locations of faults or weakness, we can anticipate potential M > 2 seismic sources at depths of 2.0 - 3.6 km at South African gold mines. At such potential sources, we have installed instruments prior to an onset of irreversible process to monitor earthquake generation process. From the previous projects for periods of from a year to a few years, the possible widest dynamic range and resolution have revealed the finest detail of the process since 1995 in cooperation with ISS International Ltd and South African gold mines (Mponeng, Bambanani, Tau Tona, Buffelsfontein GM, and ERPM), Wits Univ., Geohydroseis CC., Seismogen CC., OHMS CC., GFZ, GMuG, CSIR. The talk summarizes examples of our successful monitoring and introduces some on-going projects. Highlighted are the following. Yamada et al. [05, 07] demonstrated that mine tremors have rupture process as complex as natural larger earthquakes and the scale dependency of rupture parameters is similar to that for natural larger earthquakes. We successfully recorded strain accumulations larger than 100 micro strain, followed by several hundreds of seismic events (-1 < M < 3; distance < ~ 250 m). The seismicity within about 100m from strainmeters caused frequent, seismic strain-steps; the largest recorded was greater than 100 micro strain by an M2.5 earthquake at a distance within ~100 m. One of the most important results were that no detectable accelerating precursors preceded strain-steps associated with several hundreds of the earthquakes (- 1 < M < 3) catalogued by mine's seismic networks (hereinafter Catalogued E/Q; Takeuchi 05), while significant post-seismic drifts followed some strain-steps by Catalogued E/Qs. Frequently observed were episodic strain changes with durations of much slower than strain-steps associated with the Catalogued E/Qs [Naoi et al. 06]. Striking were some examples

  7. Apollo 14 and 16 Active Seismic Experiments, and Apollo 17 Lunar Seismic Profiling

    NASA Technical Reports Server (NTRS)

    1976-01-01

    Seismic refraction experiments were conducted on the moon by Apollo astronauts during missions 14, 16, and 17. Seismic velocities of 104, 108, 92, 114 and 100 m/sec were inferred for the lunar regolith at the Apollo 12, 14, 15, 16, and 17 landing sites, respectively. These data indicate that fragmentation and comminution caused by meteoroid impacts has produced a layer of remarkably uniform seismic properties moonwide. Brecciation and high porosity are the probable causes of the very low velocities observed in the lunar regolith. Apollo 17 seismic data revealed that the seismic velocity increases very rapidly with depth to 4.7 km/sec at a depth of 1.4 km. Such a large velocity change is suggestive of compositional and textural changes and is compatible with a model of fractured basaltic flows overlying anorthositic breccias. 'Thermal' moonquakes were also detected at the Apollo 17 site, becoming increasingly frequent after sunrise and reaching a maximum at sunset. The source of these quakes could possibly be landsliding.

  8. African American Women's Sexual Objectification Experiences: A Qualitative Study

    ERIC Educational Resources Information Center

    Watson, Laurel B.; Robinson, Dawn; Dispenza, Franco; Nazari, Negar

    2012-01-01

    The purpose of our study was to investigate African American women's experiences with sexual objectification. Utilizing grounded theory methodology as well as Black feminist thought and objectification theory as the research lenses, the results of this study uncovered how racist, sexist, and classist ideologies contributed to sexual…

  9. Early Academic Experiences of Recently Incarcerated African American Males

    ERIC Educational Resources Information Center

    Jeffers, Adam R.

    2010-01-01

    This project examines the early educational experiences of 6 young African American males (ages 18-25) who attended urban schools in San Diego, California. All 6 men were incarcerated for at least 1-year before participating in a pre-release program. The participants were part of a pre-release program in San Diego, California, which was selected…

  10. Seismic experiment reveals rifting of craton in Tanzania

    NASA Astrophysics Data System (ADS)

    Nyblade, Andrew A.; Langston, Charles A.; Last, Robert J.; Birt, Christopher; Owens, Thomas J.

    A research project in Tanzania, East Africa, is being conducted to examine seismic velocities within the crust and upper mantle in an area where cratonic lithosphere is experiencing extensional tectonism. The results will be used to evaluate models of cratonic structure. Waveforms from several hundred teleseismic earthquakes and over 10,000 regional and local earthquakes recorded in 1994 and 1995 by the Tanzania Broadband Seismic Experiment are not only yielding new insights into deep continental structure, but are also helping to determine the tectonic stability of cratons by identifying the locus of rifting within northeastern Tanzania.

  11. The use of seismic signals by fossorial southern African mammals: a neuroethological gold mine.

    PubMed

    Narins, P M; Lewis, E R; Jarvis, J J; O'Riain, J

    1997-01-01

    Behavioral adaptations exhibited by two African fossorial mammals for the reception of vibrational signals are discussed. The Namib Desert golden mole (Eremitalpa granti namibensis) is a functionally blind, nocturnal insectivore in the family Chrysochloridae that surface forages nightly in the Namib desert. Both geophone and microphone recordings in the substrate suggest that the golden mole is able to detect termite colonies and other prey items solely using seismic cues. This animal exhibits a hypertrophied malleus, an adaptation favoring detection of low-frequency signals. In a field study of the Cape mole-rat (Georychus capensis), a subterranean rodent in the family Bathyergidae, both seismic and auditory signals were tested for their propagation characteristics. This solitary animal is entirely fossorial and apparently communicates with its conspecifics by drumming its hind legs on the burrow floor. Auditory signals attenuate rapidly in the substrate, whereas vibratory signals generated in one burrow are easily detectable in neighboring burrows. The sensitivity to substrate vibrations in two orders of burrowing mammals suggests that this sense is likely to be widespread within this taxon and may serve as a neuroethological model for understanding the evolution of vibrational communication. Neuroethological implications of these findings are discussed. PMID:9365810

  12. Financing vaccinations - the South African experience.

    PubMed

    Blecher, Mark S; Meheus, Filip; Kollipara, Aparna; Hecht, Robert; Cameron, Neil A; Pillay, Yogan; Hanna, Luisa

    2012-09-01

    South Africa provides a useful country case study for financing vaccinations. It has been an early adopter of new vaccinations and has financed these almost exclusively from domestic resources, largely through general taxation. National vaccination policy is determined by the Department of Health, based on advice from a national advisory group on immunisation. Standard health economic criteria of effectiveness, cost-effectiveness, affordability and burden of disease are used to assess whether new vaccinations should be introduced. Global guidelines and the advice of local and international experts are also helpful in making the determination to introduce new vaccines. In terms of recent decisions to introduce new vaccines against pneumococcal disease and rotavirus diarrhoea in children, the evidence has proved unequivocal. Universal rollout has been implemented even though this has led to a fivefold increase in national spending on vaccines. The total cost to government remains below 1-1.5% of public expenditures for health, which is viewed by the South African authorities as affordable and necessary given the number of lives saved and morbidity averted. To manage the rapid increase in domestic spending, efforts have been made to scale up coverage over several years, give greater attention to negotiating price reductions and, in some cases, obtain initial donations or frontloaded deliveries to facilitate earlier universal rollout. There has been strong support from a wide range of stakeholders for the early introduction of new generation vaccines. PMID:22939027

  13. Oral submucous fibrosis. The South African experience.

    PubMed

    VanWyk, C W

    1997-01-01

    A review of research related to oral submucous fibrosis (OSF) among South Africans of Indian descent shows a certain uniqueness compared to other countries. In South Africa the betel habit is more common among women, only 60% of chewers prefer the betel quid while the rest like the nut by itself, the majority of chewers prefer the baked (black) nut variety and a minority add tobacco to their chew. This pattern reflects in the distribution of OSF and the practice of the habit by OSF subjects. Compared to chewers without OSF, OSF subjects are younger and have shorter histories of chewing. Yet the profile of systemic diseases were similar among subjects with and without OSF. The habit as practised in South Africa also determines the pattern of oral squamous carcinomas. They are more common in women, with buccal mucosa cancers being the most frequent. The latter are commonly found in subjects not using any tobacco, indicating the carcinogenicity of the areca nut. It was also shown that oral cancer can develop in chewers without an intermediate precancerous OSF phase. A follow-up of OSF cases after cessation of the habit revealed that once present the disease is permanent. An analysis of cultured OSF fibroblasts demonstrated a permanent shift to larger cells theoretically capable of producing larger amounts of collagen. Thus the agents in the nut could be the initiators of the disease and its permanent character the result of a phenotypic alteration in cells from changes in gene expression. PMID:9495135

  14. Results from the apollo-12 passive seismic experiment

    USGS Publications Warehouse

    Latham, G.

    1971-01-01

    The objective of the passive seismic experiment is to measure vibrations of the lunar surface produced by all natural and artificial sources of seismic energy and to use these data to deduce the internal structure and composition of the moon, the nature of forces which may cause deformation of the moon and moonquakes, and the numbers and masses of meteoroids striking the lunar surface. The ALSEP* seismometers can magnify lunar surface vibrations 10 million times. No instrument can operate on earth with this sensitivity, because weather and man produce too much seismic noise. To obtain answers to the above questions, seismic data must be combined with data from laboratory measurements of the physical and chemical properties of surface rocks, and many other geophyiscal and geochemical measurements. Thus far, we have had the opportunity to record data from two lunar seismic stations which were installed by the astronauts during Apollo misions  and 12. The combined recording time from the stations is presently over 12 months, but there was no overlap to permit recording of the same event at two stations. 

  15. African Mask-Making Workshop: Professional Development Experiences of Diverse Participants

    ERIC Educational Resources Information Center

    Rule, Audrey C.; Montgomery, Sarah E.; Kirkland-Holmes, Gloria; Watson, Dwight C.; Ayesiga, Yvonne

    2015-01-01

    Diverse education professionals learned about African cultures in a workshop experience by making African masks using authentic symbolism. Analysis of reflections to evaluate the workshop for applicability to participants with and without African heritage showed that both groups expanded their cultural knowledge of traditional African ethnic…

  16. Seismotectonic of Southern Apennines from recent passive seismic experiments

    NASA Astrophysics Data System (ADS)

    Frepoli, A.; Maggi, C.; Cimini, G. B.; Marchetti, A.; Chiappini, M.

    2011-03-01

    We used data of local earthquakes collected during two recent passive seismic experiments carried out in southern Italy in order to study the seismotectonic setting of the Lucanian Apennine and the surrounding areas. Based on continuous recordings of the temporary stations we extracted over 15,600 waveforms, which were hand-picked along with those recorded by the permanent stations of the Italian national seismic network obtaining a dense, high-quality dataset of P- and S-arrival times. We examined the seismicity occurring in the period 2001-2008 by relocating 566 out of 1047 recorded events with magnitudes ML ≥ 1.5 and computing 162 fault-plane solutions. Earthquakes were relocated using a minimum one-dimensional velocity model previously obtained for the region and a Vp/ Vs ratio of 1.83. Background seismicity is concentrated within the upper crust (between 5 and 20 km of depth) and it is mostly clustered along the Lucanian Apennine chain axis. A significant feature extracted from this study relates to the two E-W trending clusters located in the Potentino and in the Abriola-Pietrapertosa sector (central Lucania region). Hypocentral depths in both clusters are slightly deeper than those observed beneath the Lucanian Apennine. We suggest that these two seismic features are representative of the transition from the inner portion of the chain to the external margin characterized by dextral strike-slip kinematics. In the easternmost part of the study area, below the Bradano foredeep and the Apulia foreland, seismicity is generally deeper and more scattered. The sparse seismicity localized in the Sibari Plain, in the offshore area along the northeastern Calabrian coast and in the Taranto Gulf is also investigated thanks to the new recordings. This seismicity shows hypocenters between 12 and 20 km of depth below the Sibari Plain and is deeper (foci between 10 and 35 km of depth) in the offshore area of the Taranto Gulf. 102 well-constrained fault-plane solutions

  17. A Community Seismic Experiment in the ENAM Primary Site

    NASA Astrophysics Data System (ADS)

    Van Avendonk, H. J.

    2012-12-01

    Eastern North America (ENAM) was chosen as a GeoPRISMS Rift Initiation and Evolution primary site because it represents a mature continental margin with onshore and offshore rift basins in which the record of extension and continental break-up is preserved. The degree to which syn-rift magmatism and preexisting lithospheric weaknesses controlled the evolution of the margin can be further investigated if we image its 3-D structure at small and large length scales with active-source and earthquake seismic imaging. In the Summer of 2012 we submitted a proposal to the US National Science Foundation for an ambitious plan for data acquisition on a 400 km wide section of the mid-Atlantic East Coast margin around Cape Hatteras, from unextended continental lithosphere onshore to mature oceanic lithosphere offshore. This area includes an important along-strike transition in the morphology of the margin from the Carolina Trough to the Baltimore Canyon Trough, and two major fracture zones that are associated with significant offsets at the modern Mid-Atlantic Ridge. The study area also covers several features representing the post-rift modification of the margin by slope instability and fluid flow. As the Earthscope Transportable Array reaches the East Coast of the US in 2013 and 2014, we will have an unprecedented opportunity to image the detailed structure of the rifted margin. To make effective use of the research infrastructure, including the seismic vessel R/V Marcus Langseth, the Earthscope seismic instrumentation, and US OBS Instrument Pool, we propose to collect a suite of seismic data at the mid-Atlantic margin in the context of a community-driven experiment with completely open data access. This multi-faceted seismic experiment offers an immense opportunity for education of young scientists. We propose an integrated education effort during and after acquisition. The science and field parties for data acquisition will largely consist of young scientists, who will be

  18. The SEIS experiment : a Mars seismic package

    NASA Astrophysics Data System (ADS)

    Schibler, P.; Lognonne, P.; Giardini, D.; Banerdt, B.; Karczewski, J. F.; Mimoun, D.; Zweifel, P.; Pike, W. T.; Seis Team

    2003-04-01

    The determination of the deep internal structure of Mars, especially the state and size of the core, the structure of the mantle and shape of discontinuities will be the goal of a the SEIS experiment, which integrates a Very Broad Band 2 axis seismometer, a 3 axis short period seismometer and a serie of environmental sensors for pressure, infrasounds and temperature. We describe the scientific objective of the experiment. We then focuse on the technical description of the package of sensors, which will allow: - to measure signals in an ultra-broad band, from the tidal frequencies (0.05 mHz) up to the short period frequencies (50 Hz) - to perform environmental decorrelations of the temperature and pressure variation on Mars, allowing the sensor to operate in a thermal environment with daily variations of about 40°K - to search for infrasounds which might be associated to dust devils and atmospheric discharge. The overall mass of the SEIS experiment is 2.3 kg, including all sensors, data control processors and installation devices. Acquisition will be performed by a series of 24 bits A/D converters, while the thermal and drift control will be performed by a feedback generated by a 24 bits D/A converter. Two VBB axis will be delivered by industry at mid 2003 and functional breadboard of sphere (15 cm diameter) containing 2 VBB axis, environmental sensors and electronics will be delivered at the end of 2003. IPGP has the overall responsibility of the experiment and is responsible for the VBB sensor and environmental sensors. ETHZ is responsible for the electronics of the experiment and JPL for the Short Period sensors. The SEIS is one of the core instruments of the Netlander mission, which objective is to deploy in 2009 a network of 4 stations on Mars for one Martian year of operation. This design of "multiparameter station" can be used for other Martian missions (e.g. Mars SmartLander) and a simplified and lighter instrument could also be proposed on other planet

  19. Seismic imaging of sandbox experiments - laboratory hardware setup and first reflection seismic sections

    NASA Astrophysics Data System (ADS)

    Krawczyk, C. M.; Buddensiek, M.-L.; Oncken, O.; Kukowski, N.

    2012-10-01

    With the study and technical development introduced here, we combine analogue sandbox simulation techniques with seismic physical modelling of sandbox models. For that purpose, we designed and developed a new mini-seismic facility for laboratory use, comprising a seismic tank, a PC-driven control unit, a positioning system, and piezo-electric transducers used here the first time in an array mode. To assess the possibilities and limits of seismic imaging of small-scale structures in sandbox models, different geometry setups were tested in the first experiments that also tested the proper functioning of the device and studied the seismo-elastic properties of the granular media used. Simple two-layer models of different materials and layer thicknesses as well as a more complex model comprising channels and shear zones were tested using different acquisition geometries and signal properties. We suggest using well sorted and well rounded grains with little surface roughness (glass beads). Source receiver-offsets less than 14 cm for imaging structures as small as 2.0-1.5 mm size have proven feasible. This is the best compromise between wide beam and high energy output, and being applicable with a consistent waveform. Resolution of the interfaces of layers of granular materials depends on the interface preparation rather than on the material itself. Flat grading of interfaces and powder coverage yields the clearest interface reflections. Finally, sandbox seismic sections provide images of very good quality showing constant thickness layers as well as predefined channel structures and fault traces from shear zones. Since these can be regarded in sandbox models as zones of decompaction, they behave as reflectors and can be imaged. The multiple-offset surveying introduced here improves the quality with respect to S/N-ratio and source signature even more; the maximum depth penetration in glass bead layers thereby amounts to 5 cm. Thus, the presented mini-seismic device is

  20. Deep crustal structure of the North-West African margin from combined wide-angle and reflection seismic data (MIRROR seismic survey)

    NASA Astrophysics Data System (ADS)

    Biari, Y.; Klingelhoefer, F.; Sahabi, M.; Aslanian, D.; Schnurle, P.; Berglar, K.; Moulin, M.; Mehdi, K.; Graindorge, D.; Evain, M.; Benabdellouahed, M.; Reichert, C.

    2015-08-01

    The structure of the Moroccan and Nova Scotia conjugate rifted margins is of key importance for understanding the Mesozoic break-up and evolution of the northern central Atlantic Ocean basin. Seven combined multichannel reflection (MCS) and wide-angle seismic (OBS) data profiles were acquired along the Atlantic Moroccan margin between the latitudes of 31.5° and 33° N during the MIRROR seismic survey in 2011, in order to image the transition from continental to oceanic crust, to study the variation in crustal structure, and to characterize the crust under the West African Coast Magnetic Anomaly (WACMA). The data were modeled using a forward modeling approach. The final models image crustal thinning from 36 km thickness below the continent to approximately 8 km in the oceanic domain. A 100 km wide zone characterized by rough basement topography and high seismic velocities up to 7.4 km/s in the lower crust is observed westward of the West African Coast Magnetic Anomaly. No basin underlain by continental crust has been imaged in this region, as has been identified north of our study area. Comparison to the conjugate Nova Scotian margin shows a similar continental crustal thickness and layer geometry, and the existence of exhumed and serpentinized upper mantle material on the Canadian side only. The oceanic crustal thickness is lower on the Canadian margin.

  1. Full seismic waveform inversion of the African crust and Mantle - Initial Results

    NASA Astrophysics Data System (ADS)

    Afanasiev, Michael; Ermert, Laura; Staring, Myrna; Trampert, Jeannot; Fichtner, Andreas

    2016-04-01

    We report on the progress of a continental-scale full-waveform inversion (FWI) of Africa. From a geodynamic perspective, Africa presents an especially interesting case. This interest stems from the presence of several anomalous features such as a triple junction in the Afar region, a broad region of high topography to the south, and several smaller surface expressions such as the Cameroon Volcanic Line and Congo Basin. The mechanisms behind these anomalies are not fully clear, and debate on their origin spans causative mechanisms from isostatic forcing, to the influence of localized asthenospheric upwelling, to the presence of deep mantle plumes. As well, the connection of these features to the African LLSVP is uncertain. Tomographic images of Africa present unique challenges due to uneven station coverage: while tectonically active areas such as the Afar rift are well sampled, much of the continent exhibits a severe dearth of seismic stations. As well, while mostly surrounded by tectonically active spreading plate boundaries (a fact which contributes to the difficulties in explaining the South's high topography), sizeable seismic events (M > 5) in the continent's interior are relatively rare. To deal with these issues, we present a combined earthquake and ambient noise full-waveform inversion of Africa. The noise component serves to boost near-surface sensitivity, and aids in mitigating issues related to the sparse source / station coverage. The earthquake component, which includes local and teleseismic sources, aims to better resolve deeper structure. This component also has the added benefit of being especially useful in the search for mantle plumes: synthetic tests have shown that the subtle scattering of elastic waves off mantle plumes makes the plumes an ideal target for FWI [1]. We hope that this new model presents a fresh high-resolution image of sub-African geodynamic structure, and helps advance the debate regarding the causative mechanisms of its surface

  2. Older African American Women’s Lived Experiences with Depression

    PubMed Central

    Ward, Earlise C.; Mengesha, Maigenete; Issa, Fathiya

    2014-01-01

    Little is known about older African American women’s lived experiences with depression. What does depression mean to this group? What are they doing about their depression? Unfortunately, these questions are unanswered. This study examined older African American women’s lived experiences with depression and coping behaviours. The common sense model provided the theoretical framework for present study. Thirteen community-dwelling African American women aged 60 and older (M =71 years) participated. Using qualitative phenomenological data analysis, results showed the women held beliefs about factors that can cause depression including experiences of trauma, poverty, and disempowerment. Results also indicated the women believed that depression is a normal reaction to life circumstances and did not see the need to seek professional treatment for depression. They coped by use of culturally-sanctioned behaviours including religious practices and resilience. It appears these women’s beliefs about depression and use of culturally-sanctioned coping behaviours might potentially be a barrier to seeking professional mental health care, which could result in missed opportunities for early diagnosis and treatment of depression among this group. Implications for research, educational and clinical interventions are discussed. PMID:23742034

  3. Free online seismic data from a sand tank experiment

    NASA Astrophysics Data System (ADS)

    Lorenzo, J. M.; Smolkin, D.; White, C.; Chollett, S.; Sun, T.

    2012-12-01

    Theoretical fluid flow models are used regularly to predict and analyze porous media flow but require verification against natural systems. Seismic monitoring in a controlled laboratory setting at a nominal scale of 1:1000 in the acoustic frequency range can help improve fluid flow models as well as elasto-granular models for uncompacted, saturated-unsaturated soils. A mid-scale sand tank allows for many highly repeatable, yet flexible, experimental configurations with different material compositions and pump rates while still capturing phenomena such as patchy saturation, flow fingering, or layering. The tank (~6 x 9 x 0.44 m) contains a heterogeneous sand pack (1.52-1.7 phi). In a set of eight experiments the water table is raised inside the sand body at increments of ~0.05 m. Seismic events (vertical component) are recorded by a pseudo-walkaway 64-channel accelerometer array (20 Hz-20 kHz), at 78 kS/s, in 100- scan stacks so as to optimize signal-to-noise. Three screened well sites monitor water depth (+/- 3 mm) inside the sand body. Data sets comprise SEG-Y formatted files (seismic) and are publicly downloadable from the internet (http://github.com/cageo/Lorenzo-2012), in order to allow comparisons of different seismic and fluid flow analyses. The capillary fringe does not appear to completely saturate, as expected, because the interpreted compressional-wave velocity values remain so low (< 210 m/s). Even the highest water levels there is no large seismic impedance contrast across the top of the water table to generate a clear reflector. Preliminary results indicate an immediate need for several additional experiments whose data sets will be added to the online database. Future benchmark data sets will grow with a control data set to show conditions in the sand body before water levels rise, and a surface 3D data set. In later experiments, buried sensors will help reduce seismic attenuation effects and in-situ saturation sensors will provide calibration values.

  4. An Examination of African American Female College Presidents' Professional Ascendancy and Mentoring Experiences

    ERIC Educational Resources Information Center

    Smith-Ligon, Pamela

    2011-01-01

    There is a large disparity in the number of African American women leaders in higher education, specifically in the presidency. Much of the literature negates the experiences of the African American woman, often fusing their experiences with those of all women, or those of African American men, which often disregards the challenges and successes…

  5. Pedagogies of Experience: A Case of the African American Male Teacher

    ERIC Educational Resources Information Center

    Brown, Anthony L.

    2011-01-01

    Numerous scholars have illustrated how African American teachers' past experiences provide them a philosophical vision committed to teaching for social and educational change for African American students. This article draws from this body of work by looking at the diverse ways five African American male teachers used their past experiences to…

  6. Seismicity Patterns and Magmatic Processes in the Rwenzori Region, East-African Rift

    NASA Astrophysics Data System (ADS)

    Lindenfeld, M.; Rumpker, G.; Schmeling, H.; Wallner, H.

    2010-12-01

    The 5000m high Rwenzori Mountains are situated within the western branch of the East African Rift System (EARS), at the border between Uganda and the Democratic Republic of Congo. They represent a basement block located within the rift valley whose origin and relation to the evolution of the EARS are highly puzzling. During a recent seismological campaign we located more than 800 earthquakes per month with magnitudes ranging from 0.5 to 5.1. Vertical sections across the northern parts of the Rwenzoris show, that west of the mountains (towards the rift valley) the focal depths range from 10 to 20 km, whereas the hypocentres go as deep as 30 km on the eastern side. This is in good agreement with Moho-depths derived from receiver functions and implies that all of these events are located within the crust. However, about 30 km east of the northern mountain ridge we located a cluster of 7 events that exhibit an anomalous depth of about 60 km. We can confidently locate these earthquakes within the mantle lithosphere beneath the rift. The existence of earthquakes at this depth is enigmatic, especially within a rifting regime were one expects hot and weak material relatively close to the surface. We think that these events are possibly related to the evolution of the Rwenzori Mountains. A recent hypothesis to explain the extreme uplift of the Rwenzori Mountains is rift induced delamination (RID) of mantle lithosphere. Here we show that the RID-process is indeed capable of explaining the seismic energy release in the mantle. However, in view of the specific hypocentral location of the event cluster, magmatic impregnation processes associated with dyke propagation into the mantle lithosphere may be a more realistic cause for seismic radiation at the observed depth. Crustal earthquakes northeast of the Rwenzori area are relocated with a double-difference algorithm to improve the spatial resolution of seismicity pattern. Several event clusters in the vicinity of the Fort

  7. IRIS Controlled Source Seismic Experiments: Continental Structure, Instrumentation, and Education

    NASA Astrophysics Data System (ADS)

    Mooney, W. D.; Keller, G. R.

    2004-12-01

    The controlled-source seismology program of IRIS/PASSCAL has made major contributions to the study of continental structure and evolution. It has also undergone major developments in seismic instrumentation. The first PASSCAL experiments (1984/85) targeted the Basin and Range Province and the Ouachita orogenic belt. The Basin and Range study provided remarkably clear images of this thin, highly-extended crust, while the Ouachita experiment tested competing hypotheses for the deep structure of this Paleozoic orogen. However, both of these projects were limited by a lack of seismic instruments. The situation improved in the late 1980's with the benefit of a mixed array of 600 seismic recorders from the USGS, Stanford, and the Geological Survey of Canada. The resolution achieved with these instruments was revolutionary. Results include the imaging of such remarkable features as crustal-scale duplexes in the Brooks Range compressional orogen of northern Alaska, and of crustal "core complexes" in the extended crust of southwest Arizona. The 3-channel PASSCAL Jr. instrument was developed, leading to experiments in which ˜1000 instruments were deployed, including three-component recording. This complex mix of instruments served the community well for several years, but required large, complex instrument centers and lots of technical support. With input from PASSCAL and the international community, a newly designed, compact instrument (the Texan) was finalized in the spring of 1998, and the first 200 instruments was delivered to the Univ. of Texas-El Paso in late 1998. The present instrument pool of Texans exceeds 1,400 and these have been used on such projects as the high-resolution imaging of the Los Angeles and San Fernando basins (LARSE I and II experiments), where active thrust faults have been imaged. Controlled-source seismic experiments are now very numerous. During calendar year 2004 alone, portable Texan instruments have traveled from Venezuela to Denmark

  8. The lived experience of informal African American male caregivers.

    PubMed

    Weinland, Jo Ann

    2009-03-01

    Informal caregivers play a major role in providing care to loved ones within the home and demands for dependent care are likely to increase. Informal caregivers are likely to continue to be responsible for the majority of care for loved ones living well into late stages of life. This article describes the lived experience of African American men providing care to a relative within the home and explores their definition of caregiver distress. The phenomenological study was conducted using face-to-face interviews with 10 Christian African American men. Demographic data about the caregiver and the care recipient were collected. Common themes included: commitment, support (family support and formal health-related support), spirituality, and caregiver burden (stress, time strain and financial strain). Implications include the need for health care providers to expand their knowledge related to the diversity of caregivers and to use culturally relevant comprehensive assessments of caregivers and recipients, discharge planning tools, and community resources. PMID:19477717

  9. Experiences and Learning Needs of African American Family Dementia Caregivers.

    PubMed

    Samson, Zoe Blake; Parker, Monica; Dye, Clinton; Hepburn, Kenneth

    2016-09-01

    Dementia family caregivers display significant rates of psychological and physical symptoms. African Americans (AAs) are disproportionately affected by dementia. African American caregivers display unique patterns of symptomology and responses to interventions designed to promote caregiver well-being. This study analyzed qualitative focus group data from 32 AA caregivers to explore how issues of race and culture may be incorporated into a culturally sensitive intervention for AA dementia family caregivers. Caregivers were asked scripted questions about their caregiving experiences and to suggest alterations to an existing psychoeducation program. Analysis revealed 4 key themes: the tradition of family care, caregiving and caregiving issues, culturally appropriate care, and navigating without a map. Suggestions for an educational program included a focus on developing caregiver skills and knowledge for caregiving, promotion of self-care, and reflection on the AA family and community as resources for care. PMID:26953236

  10. 3D Seismic Reflection Experiment over the Galicia Deep Basin

    NASA Astrophysics Data System (ADS)

    Sawyer, D. S.; Jordan, B.; Reston, T. J.; Minshull, T. A.; Klaeschen, D.; Ranero, C.; Shillington, D. J.; Morgan, J. K.

    2014-12-01

    In June thru September, 2013, a 3D reflection and a long offset seismic experiment were conducted at the Galicia rifted margin by investigators from the US, UK, Germany, and Spain. The 3D multichannel experiment covered 64 km by 20 km (1280 km2), using the RV Marcus Langseth. Four streamers 6 km long were deployed at 12.5 m hydrophone channel spacing. The streamers were 200 m apart. Two airgun arrays, each 3300 cu in, were fired alternately every 37.5 m, to collectively yield a 400 m wide sail line consisting of 8 CMP lines at 50 m spacing. The long offset seismic experiment included 72 short period OBS's deployed below the 3D reflection survey box. Most of the instruments recorded all the shots from the airgun array shots. The 3D seismic box covered a variety of geologic features. The Peridotite Ridge (PR), is associated with the exhumation of upper mantle rocks to the seafloor during the final stage of the continental separation between the Galicia Bank and the Grand Banks of Newfoundland. The S reflector is present below most of the continental blocks under the deep Galicia basin. S is interpreted to be a low-angle detachment fault formed late in the rifting process, and a number of rotated fault block basins and ranges containing pre and syn-rift sediments. Initial observations from stacked 3D seismic data, and samples of 2D pre-stack time migrated (PSTM) 3D seismic data show that the PR is elevated above the present seafloor in the South and not exposed through the seafloor in the North. The relative smoothness of the PR surface for the entire 20 km N-S contrasts with the more complex, shorter wavelength, faulting of the continental crustal blocks to the east. The PR does not seem to show offsets or any apparent internal structure. The PSTM dip lines show substantial improvement for the structures in the deep sedimentary basin East of the PR. These seem to extend the S reflector somewhat farther to the West. The migrated data show a substantial network of

  11. Seismic structure of the crust and lithospheric mantle of the southern African cratonic region

    NASA Astrophysics Data System (ADS)

    Youssof, M.; Thybo, H.; Artemieva, I. M.; Levander, A.

    2013-12-01

    We present a new seismic model for the structure of the crust and lithospheric mantle in southern Africa constrained by a joint study of seismic receiver functions and finite-frequency tomography, using the high-quality data from the South Africa Seismic Experiment (SASE). A) The crust has a highly heterogeneous structure with short wavelength variations in (i) thickness, (ii) composition (reflected in Vp/Vs-ratio calculated for all SASE stations), and (iii) Moho sharpness (which is quantified and mapped for the entire region) (Youssof et al., Tectonophysics, in review). By mapping these three parameters, we distinguish ~20 crustal blocks that do not everywhere coincide with surface tectonic features. Our RFs also demonstrate strong azimuthal anisotropy in the crust, with a typical crustal contribution to the total S-wave splitting of at least 30%. Spatial correlation of the S-wave polarization directions of crustal and mantle anisotropy indicates (i) the presence of three distinct Archean lithospheric terranes and (ii) coupling between the crust and lithospheric mantle in most of the study area, with a strong decoupling in western Kaapvaal where the crustal anisotropy is strongest. The similarity of anisotropy directions in the crust and mantle beneath much of the Kaapvaal craton indicates that (a) the seismic anisotropy originates at the time of cratonization and (b) the observed correspondence between the present direction of absolute plate motion (APM) and lithosphere anisotropy is coincidental. B) A new 3D high-resolution seismic model of the lithospheric mantle has been determined from finite frequency tomographic inversions of teleseismic P- and S- body wave data. The two velocity models are very similar in structure, but differ in the relative P- and S-wave velocity anomalies. We find that: 1) the fast lithospheric keels extends very deep, perhaps to depths of 300-350 km and 250 km beneath the Kaapvaal and Zimbabwe cratons, respectively, and 2) the Archean

  12. Seismic tomography Technology for the Water Infiltration Experiment

    SciTech Connect

    J. Descour

    2001-04-30

    NSA Engineering, Inc., conducted seismic tomography surveys in Niche No.3 in the Exploratory Studies Facility (ESF), Yucca Mountain, Nevada, and Alcove No.8 in the Enhanced Characterization of the Repository Block (ECRB) cross drift as part of the Infiltration Experiment being conducted in Niche No.3. NSA Engineering is a direct support contractor to the Yucca Mountain Project. This report documents the work performed from August 14 through 30, 2000, prior to the beginning of the infiltration experiment. The objective of the seismic tomography survey was to investigate the flow path of water between access drifts and more specifically to (Kramer 2000): (1) Conduct a baseline seismic tomography survey prior to the infiltration experiment; (2) Produce 2-D and 3-D tomographic images of the rock volume between Alcove No.8 and Niche No.3; (3) Correlate tomography results with published structural and lithological features, and with other geophysical data such as ground penetrating radar (GPR); and (4) Results of this survey will form a baseline with which to compare subsequent changes to the rock mass. These changes may be as a result of the water infiltration tests that could be conducted in Alcove No.8 in 2001. The scope of this reported work is to use the velocity tomograms to: (a) assess the structures and lithologic features within the surveyed area and/or volume between the two access drifts; and (b) provide information on the structural state of the rock mass as inferred by the velocity signatures of the rock prior to the beginning of the infiltration experiment.

  13. The experiences of African American graduate students: A cultural transition

    NASA Astrophysics Data System (ADS)

    Joseph, Joretta

    Historically Black Colleges and Universities (HBCU) have long been an intellectual resource for the African American community. HBCUs have provided and continue to provide an educational pathway for many Black students, particularly women who seek graduate and advanced degrees. However, despite the overwhelmingly positive presence of HBCU in the African American community, the academic training of students who graduate from HBCUs may be perceived as insufficient by predominantly White graduate institutions (PWIs). As a result, African American students who are not well integrated into their respective departmental communities and cultures at PW/is are likely to leave graduate school. Thus the continuing loss of talented people, potential research, role models for society, and the next generation of African American students in the fields of math, engineering, and the sciences (STEM) create a segregated and limited university environment. Studies in the field that attempt to provide insight in to experiences of underrepresented students are ultimately beneficial. However, often such studies do not address the process of adapting to the culture of a predominantly white institution (PWI), particularly within white and male dominated fields such as mathematics and the sciences. Research has also indicated that the first two years at a predominantly white graduate institution is the crucial transitional period for students of color, and it is this transitional moment in time that is the focus of this study. I consider how students make the transition from HBCU to majority institutions, and what impact this transition has on their persistence and commitment to their discipline. The limited amount of research that does address the experiences of minority doctoral students in math and science is usually coupled with the experiences of women. However, race and gender are not linear or additive. It cannot be assumed that the same factors that effect the under representation

  14. Characterisation of rockfalls from seismic signal: insights from laboratory experiments

    NASA Astrophysics Data System (ADS)

    Farin, Maxime; Mangeney, Anne; Toussaint, Renaud; de Rosny, Julien; Shapiro, Nikolai; Dewez, Thomas; Hibert, Clément; Mathon, Christian; Sedan, Olivier; Berger, Frédéric

    2015-04-01

    Rockfalls, debris flows and rock avalanches represent a major natural hazard for the population in mountainous, volcanic and coastal areas but their direct observation on the field is very difficult. Recent field studies showed that gravitational instabilities can be detected, localized and characterized thanks to the seismic signal they generate. Therefore, a burning challenge for risks assessment related to these events is to obtain quantiative informations on the characteristics of the rockfalls (mass, speed, extension,...) from the properties of the signal (seismic energy, frequencies,...). Using a theoretical model of viscoelastic impact of a sphere on a plane, we develop analytical scaling laws relating the energy radiated in elastic waves, the energy dissipated in viscoelasticity during the impact and the frequencies of the generated seismic signal to the mass m and the impact speed V z of the sphere and to the elastic parameters of the involved materials. The radiated elastic energy is shown to vary as m5/3V z11/5 on plates and as mV z13/5 on blocks, regardless of the elastic parameters. The energy dissipated in viscoelasticity does not depend on the support thickness and varies as m2/3V z11/5. The mean frequency of the generated signal is inversely proportional to the impact duration. Then, we conduct simple laboratory experiments that consist in dropping spherical beads of different size and materials and small gravels on thin plates of glass and PMMA and rock blocks. In the experiments, piezoelectric accelerometers are used to record the signals in a wide frequency range: 1 Hz to 56 kHz. The experiments are also monitored optically using fast cameras. The elastic energy emitted by an impact on the supports is first quantitatively estimated and compared to the potential energy of fall and to the potential energy change during the shock. We observe a quantitative agreement between experimental data and the analytical scaling laws, even when we use small

  15. The Meaning of KMT (Ancient Egyptian) History for Contemporary African American Experience.

    ERIC Educational Resources Information Center

    Hilliard, Asa G., III

    1992-01-01

    Explores the history of KMT (ancient Egypt) and its importance for contemporary African-American experience. Reviews evidence that ancient Egypt was a black African population bound by history and culture to the rest of Africa. The rescue of Kemetic history can restore a sense of heritage to African Americans. (SLD)

  16. Resiliency in Physics: The Lived Experiences of African-American Women Who Completed Doctoral Physics Programs

    ERIC Educational Resources Information Center

    Burnette, Samara Fleming

    2013-01-01

    Currently, little is known about African-American women with doctoral degrees in physics. This study examined the lived experiences of African-American women who completed doctoral programs in physics. Due to factors of race and gender, African-American women automatically enter a double-bind in science, technology, engineering, and mathematics…

  17. 3D Seismic Reflection Experiment Over the Galicia Deep Basin

    NASA Astrophysics Data System (ADS)

    Sawyer, Dale; Jordan, Brian; Tesi Sanjurjo, Mari; Alexanian, Ara; Morgan, Julia; Shillington, Donna; Reston, Timothy; Minshull, Timothy; Klaeschen, Dirk; Ranero, César

    2014-05-01

    In June thru September, 2013, a 3D reflection and a long offset seismic experiment were conducted at the Galicia rifted margin by investigators from the US, UK, Germany, and Spain. The 3D multichannel experiment covered 64 km by 20 km (1280 km2), using the RV Marcus Langseth. Four streamers 6 km long were deployed at 12.5 m hydrophone channel spacing. The streamers were 200 m apart. Two airgun arrays, each 3300 cu in, were fired alternately every 37.5 m, to collectively yield a 400 m wide sail line consisting of 8 CMP lines at 50 m spacing. The long offset seismic experiment included 72 short period OBS's deployed below the 3D reflection survey box. Most of the instruments recorded all the shots from the airgun array shots. The 3D seismic box covered a variety of geologic features. The Peridotite Ridge (PR), is associated with the exhumation of upper mantle rocks to the seafloor during the final stage of the continental separation between the Galicia Bank and the Grand Banks of Newfoundland. The S reflector is present below most of the continental blocks under the deep Galicia basin. S is interpreted to be a low-angle detachment fault formed late in the rifting process, and a number of rotated fault block basins and ranges containing pre and syn-rift sediments. Initial observations from stacked, but not yet migrated, 3D seismic data show that the PR is elevated above the present seafloor in the South and not exposed through the seafloor in the North. The relative smoothness of the PR surface for the entire 20 km N-S contrasts with the more complex, shorter wavelength, faulting of the continental crustal blocks to the east. The PR does not seem to show offsets or any apparent internal structure. However, migration will be required to see internal structure of the PR. Between the PR and the western most rifted continental crustal blocks, is a sedimentary basin about as wide as the PR and very different from the sedimentary basins bounded by the continental crustal

  18. Seismic amplification within the Seattle Basin, Washington State: Insights from SHIPS seismic tomography experiments

    USGS Publications Warehouse

    Snelson, C.M.; Brocher, T.M.; Miller, K.C.; Pratt, T.L.; Trehu, A.M.

    2007-01-01

    Recent observations indicate that the Seattle sedimentary basin, underlying Seattle and other urban centers in the Puget Lowland, Washington, amplifies long-period (1-5 sec) weak ground motions by factors of 10 or more. We computed east-trending P- and S-wave velocity models across the Seattle basin from Seismic Hazard Investigations of Puget Sound (SHIPS) experiments to better characterize the seismic hazard the basin poses. The 3D tomographic models, which resolve features to a depth of 10 km, for the first time define the P- and S-wave velocity structure of the eastern end of the basin. The basin, which contains sedimentary rocks of Eocene to Holocene, is broadly symmetric in east-west section and reaches a maximum thickness of 6 km along our profile beneath north Seattle. A comparison of our velocity model with coincident amplification curves for weak ground motions produced by the 1999 Chi-Chi earthquake suggests that the distribution of Quaternary deposits and reduced velocity gradients in the upper part of the basement east of Seattle have significance in forecasting variations in seismic-wave amplification across the basin. Specifically, eastward increases in the amplification of 0.2- to 5-Hz energy correlate with locally thicker unconsolidated deposits and a change from Crescent Formation basement to pre-Tertiary Cascadia basement. These models define the extent of the Seattle basin, the Seattle fault, and the geometry of the basement contact, giving insight into the tectonic evolution of the Seattle basin and its influence on ground shaking.

  19. The BOrborema Deep Electromagnetic and Seismic (BODES) Experiment

    NASA Astrophysics Data System (ADS)

    Julià, J.; Garcia, X.; Medeiros, W. E.; Farias do Nascimento, A.

    2015-12-01

    The Borborema Province of NE Brazil is a large Precambrian domain of the Brazilian shield located in the Northeasternmost corner of South America. It is bounded by the Parnaíba basin to the West and by the São Francisco craton to the South. Its structuration in the Precambrian has been related to compressional processes during the Brasiliano-Pan African orogeny (600-550 Ma). In the Mesozoic, extensional stresses eventually leading to continental breakup, left a number of aborted rift basins within the Province. After continental breakup, the evolution of the Province was marked by episodes of uplift, which might have been coeval with episodes of Cenozoic volcanism. The most prominent expression of those uplift processes is the Borborema Plateau, an elliptically shaped topographic feature in the eastern half of the Province with maximum elevations of ~1200 m. The origin of uplift in the Plateau has been the focus of a number of multi-institutional and multi-disciplinary studies in the past few years, which have imaged the deep structure of the eastern Province with unprecedented detail. The origin of uplift in the western Province, which includes a superb example of basin inversion demonstrated by the ~1000 km elevations of the Chapada do Araripe, however, has been seldom investigated. With the goal of investigating the deep structure of the western Province, a temporary network of 10 collocated seismic and magnetotelluric stations was deployed in the region. The collocated stations were arranged in an approximately NS direction, with an interspation spacing of ~70 km and spanning a total length of ~600 km. The seismic stations consisted of broadband sensors (RefTek 151B-120 "Observer") sampling at 100 Hz and were deployed in January 2015; the MT stations consisted of long-period magnetotelluric (LEMI) systems, sampling at 1 Hz and 4 Hz, and were deployed in April 2015 for a period of ~2 weeks. Preliminary results based on teleseismic P-wave receiver functions

  20. Factors Influencing Dating Experiences Among African American Emerging Adults

    PubMed Central

    Hall, Naomi M.; Lee, Anna K.; Witherspoon, Daphne D.

    2014-01-01

    This study examined sociocultural factors that impact dating and sexual experiences of heterosexual African American undergraduate college students attending a historically Black institution in the Southeastern United States. Specifically, mate availability and relationship involvement were analyzed to document students’ experiences, and how these influences may be associated with sexual decision making and behavior. Data from nine focus groups (N = 57) were aggregated and four subthemes were identified: competition among women, acceptability of mates, high prevalence of casual relationships, and lowered expectations for commitment. Power dynamics emerged as a contributing factor to the types of relationship involvement, sexual decision-making, and behavior among participants. The importance of prevention programs focusing on situational and cultural variables is highlighted. Additionally, implications for professionals working with emerging adults to consider the impact of the gender ratio imbalance, and perceived power distributions on perceptions of dating relationships, and sexual decision making and behavior are addressed. PMID:25530924

  1. Seismic studies of a massive hydraulic fracturing experiment

    SciTech Connect

    House, L.; Keppler, H.; Kaieda, H.

    1985-01-01

    During a massive hydraulic fracturing experiment carried out at Fenton Hill, New Mexico, 850 microearthquakes, ranging in magnitudes from -3 to 0, were located reliably using arrival times recorded at a set of 5 downhole geophone stations. A subset of these events were located using an upgraded hodogram technique. The seismicity defines a tabular zone with horizontal extent of 900 m, vertical extent of 800 m, and thickness of 150 m. This zone strikes N340/sup 0/E, and dips 75/sup 0/ to the east; its position indicates that no hydraulic connection between the two predrilled wells could be achieved by the fracturing. The distribution of locations obtained from arrival times shows good agreement with those derived from hodograms. Well constrained fault plane solutions were determined for 26 of the larger microearthquakes observed at a surface seismic net. Most solutions display one nearly vertical nodal plane that strikes close to N - S, and a T axis that trends roughly E - W, in agreement with regional indicators of the least principal stress direction. 9 refs., 6 figs.

  2. Achievement and Underachievement: The Experiences of African Caribbeans

    ERIC Educational Resources Information Center

    Rhamie, Jasmine

    2012-01-01

    The disproportionate representation of African Caribbeans in all the negative educational statistics has been well documented. Despite this, there are African Caribbeans who achieve academically but relatively few studies have explored this area. This study aimed to investigate the factors that contribute to African Caribbean academic success,…

  3. Diversifying the secondary school curriculum: The African experience

    NASA Astrophysics Data System (ADS)

    Sifuna, Daniel N.

    1992-01-01

    The paper discusses some African experiences in the diversification of secondary education, which is taken to mean curriculum change in a practical or vocational direction. This approach is intended to provide a wider set of future career options than is offered in the more uniform academic curriculum. The diversification policy has generally been seen as a solution to a number of economic and social problems facing the independent African countries, notably the increasing youth unemployment and the escalating costs of formal education. Studies which have so far been carried out have, however, revealed that diversification programmes have not met the intended objectives, although there is sustained interest in vocationalising formal education. Problems which commonly face these programmes include high unit costs, an absence of clarity in aims and objectives, a shortage of qualified teachers and the low status of vocational subjects as viewed by the students and the community. For future development, it is suggested that diversification programmes be reorganised to relate to more realistic goals through wider community participation and through the work-orientation of post-school training programmes.

  4. Cage experiments in an East African mangrove forest: a synthesis

    NASA Astrophysics Data System (ADS)

    Schrijvers, J.; Vincx, M.

    1997-12-01

    The impact of epibenthos on endobenthos has frequently been investigated for temperate saltmarsh regions by using cage exclusion experiments. Although the insight into the function of the endobenthos of mangrove forests is crucial for their management, very few cage experiments have so far been carried out in such areas. The present paper summaries the results of such experiments in a typical East African mangrove forest at Gazi Bay about 60 km south of Mombasa, Kenya. Epibenthic animals were excluded for one year in two mangrove zones which differed in forest morphology and intertidal position ( Ceriops tagal and Avicennia marina). Environmental factors and meiobenthic and macrobenthic densities were followed in a randomised block design, and procedural and exclusion effects were statistically detected. In confronting the separate responses of all faunal groups in the two mangrove zones, this synthesis gives a better insight into the tropho-dynamical interactions than the earlier separate reports on the same experiment. The ecosystem of the mangrove zones and the competitive interactions within this system provided an ideal opportunity to discover the existence of two food systems. This confirmed a strong involvement of the majority of the endobenthos in an isolated decompositional pathway in the mangrove sediment. It became clear that this exploitative competition was more important than the epibenthic predation in structuring and regulating the global endobenthic community. This synthesis therefore both demonstrates the decisive role of the endobenthos as regenators of mangrove material, and suggests that endobenthos plays a minor role as prey for the demersal or pelagic carnivores.

  5. Ogbu Revisited: Unpacking High-Achieving African American Girls' High School Experiences

    ERIC Educational Resources Information Center

    Archer-Banks, Diane A. M.; Behar-Horenstein, Linda S.

    2012-01-01

    How African American girls cope and excel amidst the discriminations and inequities they experience within U.S. educational systems has not been widely discussed in the body of research about African Americans' schooling experiences. In this study, the researchers examined the applicability of Ogbu's cultural-ecological theory to the…

  6. Representations of the Racialized Experiences of African Americans in Developmental Reading Textbooks

    ERIC Educational Resources Information Center

    Williams, Jeanine L.

    2013-01-01

    Race plays a major role in the lived experiences of African Americans. Consequently, race significantly impacts the identities and educational experiences of African American college students--many of whom require developmental reading courses. These courses, which are gateway courses in higher education, should address race along with reading…

  7. The Perceived Undergraduate Classroom Experiences of African American Women in Science, Technology, Engineering, and Mathematics (STEM)

    ERIC Educational Resources Information Center

    Holmes, Kimberly Monique

    2013-01-01

    The purpose of this dissertation study was to explore African-American women's perceptions of undergraduate STEM classroom experiences, and the ways in which those experiences have supported or hindered their persistence in physics majors. The major research question guiding this study was: How do African-American women perceive the climate and…

  8. Crustal structure of the southern margin of the African continent: Results from geophysical experiments

    NASA Astrophysics Data System (ADS)

    Stankiewicz, J.; Parsiegla, N.; Ryberg, T.; Gohl, K.; Weckmann, U.; Trumbull, R.; Weber, M.

    2008-10-01

    A number of geophysical onshore and offshore experiments were carried out along a profile across the southern margin of the African Plate in the framework of the Inkaba yeAfrica project. Refraction seismic experiments show that Moho depth decreases rapidly from over 40 km inland to around 30 km at the present coast before gently thinning out toward the Agulhas-Falkland Fracture Zone, which marks the transition zone between the continental and oceanic crust. In the region of the abruptly decreasing Moho depth, in the vicinity of the boundary between the Namaqua-Natal Mobile Belt and the Cape Fold Belt, lower crustal P-wave velocities up to 7.4 km/s are observed. This is interpreted as metabasic lithologies of Precambrian age in the Namaqua-Natal Mobile Belt, or mafic intrusions added to the base of the crust by younger magmatism. The velocity model for the upper crust has excellent resolution and is consistent with the known geological record. A joint interpretation of the velocity model with an electrical conductivity model, obtained from magnetotelluric studies, makes it possible to correlate a high-velocity anomaly north of the center of the Beattie magnetic anomaly with a highly resistive body.

  9. Overview of Results from the Endeavour Seismic Tomography Experiment

    NASA Astrophysics Data System (ADS)

    Toomey, D. R.; Hooft, E. E.; Wilcock, W. S.; Weekly, R. T.; Wells, A. E.; Soule, D. C.

    2011-12-01

    We report on our continuing analyses of a multi-scale seismic tomography experiment of the Endeavour segment of the Juan de Fuca Ridge. In August 2009 we deployed 68 four-component ocean bottom seismometers (OBSs) at 64 sites throughout a 90x50 km2 area to record seismic energy from 5567 shots of the 36-element, 6600 in.3 airgun array of the R/V Marcus G. Langseth. The experimental geometry utilized 3 nested scales and was designed to image (1) crustal thickness variations within 25 km of the axial high (0 to 900 kyr); (2) the map view heterogeneity and anisotropy of the topmost mantle beneath the spreading axis; (3) the three-dimensional structure of the crustal magmatic system and (4) the detailed three-dimensional, shallow crustal thermal structure beneath the Endeavour vent fields. The 90-km-long Endeavour segment lies between the Cobb and Endeavour overlapping spreading centers (OSCs), which are converging and thus shortening the Endeavour segment. Previous seismic reflection studies indicate that the central Endeavour segment is on a 40-km-wide plateau of greater crustal thickness that is interpreted to have developed when the ridge overrode the mantle melt anomaly associated with the Heckle seamount chain. The central Endeavour is also underlain by an axial magma chamber (AMC) reflector that is shallowest and most prominent beneath the hydrothermal fields. Geophysical studies of Endeavour thus permit investigation of the competing effects of tectonic, magmatic and hydrothermal processes on crustal structure and architecture. Ongoing analyses include tomographic inversion of first-arriving P waves that sample the upper- and mid-crustal regions, characterization of off-axis magma bodies via travel time and amplitude anomalies of crustal phases, estimation of regional-scale crustal thickness variations from analysis of PmP arrivals and imaging of mantle structure using Pn to constrain mantle flow and melt distribution [Weekly et al.; Wells et al.; Soule et al

  10. OSI Passive Seismic Experiment at the Former Nevada Test Site

    SciTech Connect

    Sweeney, J J; Harben, P

    2010-11-11

    its effectiveness for OSI purposes has yet to be determined. For this experiment, we took a broad approach to the definition of ''resonance seismometry''; stretching it to include any means that employs passive seismic methods to infer the character of underground materials. In recent years there have been a number of advances in the use of correlation and noise analysis methods in seismology to obtain information about the subsurface. Our objective in this experiment was to use noise analysis and correlation analysis to evaluate these techniques for detecting and characterizing the underground damage zone from a nuclear explosion. The site that was chosen for the experiment was the Mackerel test in Area 4 of the former Nevada Test Site (now named the Nevada National Security Site, or NNSS). Mackerel was an underground nuclear test of less than 20 kT conducted in February of 1964 (DOENV-209-REV 15). The reason we chose this site is because there was a known apical cavity occurring at about 50 m depth above a rubble zone, and that the site had been investigated by the US Geological Survey with active seismic methods in 1965 (Watkins et al., 1967). Note that the time delay between detonation of the explosion (1964) and the time of the present survey (2010) is nearly 46 years - this would not be typical of an expected OSI under the CTBT.

  11. Acculturative Experiences of Black-African International Students

    ERIC Educational Resources Information Center

    Boafo-Arthur, Susan

    2014-01-01

    There has been a significant increase in the number of international students pursuing higher education in the U.S. since 2001. Upon arrival, students are often beset with feelings of isolation and alienation, which are characteristic of adjusting to a new culture. African International students, specifically Black-African international students,…

  12. Experiences of African American Empowerment: A Jamesian Perspective on Agency

    ERIC Educational Resources Information Center

    Curtis-Tweed, Phyllis

    2003-01-01

    This essay draws from the work of William James and three African American pragmatists, W.E.B. Du Bois, Ralph Ellison and Cornel West, to explore the moral relevance of the self as an empowered agent among African American youth. The focus is on Jamesian agency as a function of the individual's awareness of options in context, the self-empowerment…

  13. Prospective Teachers Experiences Teaching Mathematics to African American Males

    ERIC Educational Resources Information Center

    Sheppard, Peter

    2009-01-01

    This paper describes an effort to provide prospective teachers opportunities to better understand African American male students and better focus on how they learn mathematics. Prospective teachers spent 15 hours over an eight week span mentoring and tutoring African American males without the guise of practicing teachers. Qualitative data drawn…

  14. The Perpetual Homelessness of College Experiences: Tensions between Home and Campus for African American Women

    ERIC Educational Resources Information Center

    Winkle-Wagner, Rachelle

    2009-01-01

    There is an ongoing debate about whether African American students need to sever ties with their families to be successful in college. Adding nuance to this debate, this ethnographic study examines African American women's experiences of navigating family relationships in a predominantly White institution. The women described multiple pressures…

  15. Exploring the Meaning African American PETE Teacher Candidates Ascribe to Their Aquatic Experiences

    ERIC Educational Resources Information Center

    Sato, Takahiro; Hodge, Samuel R.

    2012-01-01

    Physical Education Teacher Education (PETE) programs typically require their graduates to learn to swim proficiently. However, the research base is underdeveloped regarding the aquatic experiences of African Americans in PETE programs. The purpose of this study was to explore the meaning African American PETE teacher candidates ascribe to their…

  16. Help-Seeking Experiences and Attitudes among African American, Asian American, and European American College Students

    ERIC Educational Resources Information Center

    Masuda, Akihiko; Anderson, Page L.; Twohig, Michael P.; Feinstein, Amanda B.; Chou, Ying-Yi; Wendell, Johanna W.; Stormo, Analia R.

    2009-01-01

    The study examined African American, Asian American, and European American college students' previous direct and indirect experiences of seeking professional psychological services and related attitudes. Survey data were collected from 254 European American, 182 African American and 82 Asian American college students. Results revealed that fewer…

  17. Experiences of Chinese International Students Learning English at South African Tertiary Institutions

    ERIC Educational Resources Information Center

    Ayliff, D.; Wang, G.

    2006-01-01

    This article aims to provide insight into the experiences of Chinese international students in some South African tertiary institutions. The study investigates their successes and failures in endeavouring to learn English and the culture shock and "learning shock" they endure when registering to study in an African country with an essentially…

  18. Unheard and Unseen: How Housing Insecure African American Adolescents Experience the Education System

    ERIC Educational Resources Information Center

    Ellis, Addie Lucille; Geller, Kathy D.

    2016-01-01

    This narrative study is based on stories told by African American adolescents experiencing homelessness. It offers insights into their lived experiences and describes the challenges faced in negotiating the urban education system. African American youth are disproportionately represented in the adolescent homeless demographic. "Unheard and…

  19. Emerging from the Pipeline: African American Students, Socioeconomic Status, and College Experiences and Outcomes

    ERIC Educational Resources Information Center

    Walpole, MaryBeth

    2008-01-01

    This study focuses on how social class affects the college experiences and outcomes for African American students in 4-year colleges and universities. Using a national, longitudinal data base, the findings indicate that low SES African American students have less contact with faculty, study less, are less involved with student organizations, work…

  20. An Examination of the Lived Experiences of Successful African American Men Attending a Historically Black University

    ERIC Educational Resources Information Center

    Powell, Clark R.

    2013-01-01

    This phenomenological research explored the lived experiences of successful African American men attending a Historically Black College and University (HBCU) in the Midwest. The guiding questions for the study were (a) What positive characteristics do successful African American men demonstrate at HBCUs that offset major problems, concerns, and…

  1. Black African Parents' Experiences of an Educational Psychology Service

    ERIC Educational Resources Information Center

    Lawrence, Zena

    2014-01-01

    The evidence base that explores Black African parents' experiences of an Educational Psychology Service (EPS) is limited. This article describes an exploratory mixed methods research study undertaken during 2009-2011, that explored Black African parents' engagement with a UK EPS. Quantitative data were gathered from the EPS preschool…

  2. US Geological Survey begins seismic ground response experiments in Washington State

    USGS Publications Warehouse

    Tarr, A.C.; King, K.W.

    1988-01-01

    This article briefly describes the experimental monitoring of minor seismic features caused by distant nuclear explosions, mining blasts and rhythmic human pushing against wooden homes. Some means of response prediction are outlined in Washington State and some effects of seismic amplification by weak clayey sediments are described. The results of several experiments are described. -A.Scarth

  3. Seismic while drilling: Operational experiences in Viet Nam

    SciTech Connect

    Jackson, M.; Einchcomb, C.

    1997-03-01

    The BP/Statoil alliance in Viet Nam has used seismic while drilling on four wells during the last two years. Three wells employed the Western Atlas Tomex system, and the last well, Schlumberger`s SWD system. Perceived value of seismic while drilling (SWD) lies in being able to supply real-time data linking drill bit position to a seismic picture of the well. However, once confidence in equipment and methodology is attained, SWD can influence well design and planning associated with drilling wells. More important, SWD can remove uncertainty when actually drilling wells, allowing risk assessment to be carried out more accurately and confidently.

  4. Experiences of african american parents following perinatal or pediatric death: a literature review.

    PubMed

    Boyden, Jackelyn Y; Kavanaugh, Karen; Issel, L Michele; Eldeirawi, Kamal; Meert, Kathleen L

    2014-01-01

    A child's death is one of life's most difficult experiences. Little is known about the unique factors that influence the grief experience for bereaved African American parents. Through an integrative review of 10 publications, the authors describe the grief responses, outcomes, and implications for African American parents who experience the death of a child. Four themes emerged: (a) emotional response to loss; (b) factors that added to the burden of loss; (c) coping strategies; and (d) health consequences of grief. Healthcare providers, administrators, and policymakers should be sensitive to the unique needs of African American parents following a child's death. PMID:24666143

  5. Simulation of Seismic Tunnel Detection Experiments in Heterogeneous Geological Media

    NASA Astrophysics Data System (ADS)

    Sherman, C. S.; Glaser, S. D.; Rector, J.

    2013-12-01

    Detecting covert tunnels and other underground openings is an important yet challenging problem for geophysicists, especially where geological heterogeneity is pronounced. A number of geophysical methods have been employed to solve this problem, each with varying degrees of success. We focus on the near-surface seismic techniques of surface wave backscattering, surface wave attenuation tomography, body wave diffraction imaging, and resonant imaging. We use the elastodynamic wave propagation code E3D to simulate tunnel detection experiments completed at this site for a range of synthetic fractal velocity models. The Black Diamond mine, located near Pittsburg California, is used for the field test of our analysis. Our results show that for the relatively low-frequency surface wave attenuation and backscattering methods, the maximum detectable tunnel depth in a homogenous medium is approximately equal to the wavelength of the probing Rayleigh wave. The higher-frequency body wave diffraction and resonant imaging techniques are able to locate tunnels at greater depths, but require more sophisticated analysis and are prone to greater attenuation losses. As is expected, for large values of heterogeneity amplitude, ɛ, the percent standard deviation from the mean velocity model, the average observed surface wave attenuation signal decreases and the maximum detectable tunnel depth decreases. However, for moderate values of heterogeneity amplitude (ɛ < 3%), the average surface wave attenuation signal increases and the maximum detectable tunnel depth increases. For the body wave diffraction and resonant imaging experiments, as ɛ increases the complexity of the observed signal increases, resulting in more difficult processing and interpretation. The additional scattering attenuation tends to degrade the signals significantly due to their reliance on lower amplitude and higher frequency waves.

  6. The Will to Achieve: A Phenomenological Study of the Experiences of African American High Achieving Students and Their Parents

    ERIC Educational Resources Information Center

    Spencer, Natalie Faye

    2012-01-01

    The purpose of this research study was to understand the experiences of high achieving African American students and their parents. The experiences of high achieving African American students and their parents have been missing from literature on the academic achievement of African American students. Much of the literature that has been published…

  7. The Soul of Leadership: African American Students' Experiences in Historically Black and Predominantly White Organizations

    ERIC Educational Resources Information Center

    Hotchkins, Bryan K.

    2013-01-01

    This study addresses African American students' leadership experiences at predominantly White institutions. Findings indicated participants utilized servant leadership in historically Black organizations and transformational leadership in predominantly White organizations. The differences displayed showed that participants' leadership perceptions…

  8. Bandung seismic experiment: Towards tomographic imaging by using ambient seismic noise

    NASA Astrophysics Data System (ADS)

    Pranata, Bayu; Yudistira, Tedy; Saygin, Erdinc; Cummins, Phil R.; Widiyantoro, Sri; Zulfakriza, Nugraha, Andri D.

    2016-05-01

    Bandung is one of the most densely populated cities in Indonesia with vital infrastructures. On the other hand, this area is surrounded by potential sources of earthquakes that make Bandung vulnerable to earthquakes. Structure of seismic velocity and sediment thickness are crucially needed in the earthquake hazard reduction program for Bandung. Based on this consideration, we deployed 64 seismic stations over the Bandung basin to record seismic ambient noise. In this study, we employed a cross-correlation method to the simultaneously recorded data to retrieve interstation Green's functions. We measured group velocity of the retrieved Green's functions by using frequency-time analysis technique. By the end of this project, the set of interstation group velocity will be inverted to image the shallow seismic velocity structure of the Bandung basin and its surrounding areas including Mt. Tangkuban Parahu and Lembang fault. As the first stage of this work, currently we focus on Green ' s function calculation as well as the interstation group velocity measurements. The general characteristics of group velocity can be evaluated from the plot of cross-correlation function as a function of its interstation distance.

  9. Local seismic events in area of Poland based on data from PASSEQ 2006-2008 experiment

    NASA Astrophysics Data System (ADS)

    Polkowski, Marcin; Plesiewicz, Beata; Wiszniowski, Jan; Wilde-Piórko, Monika; Passeq Working Group

    2014-05-01

    PASSEQ 2006-2008 (Passive Seismic Experiment in TESZ; Wilde-Piórko et al, 2008) was the biggest so far passive seismic experiment in the area of Central Europe (Poland, Germany, Czech Republic and Lithuania). 196 seismic stations (including 49 broadband seismometers) worked simultaneously for over two years. During experiment multiple types of data recorders and seismometers were used making analysis more complex and time consuming. Dataset was unified and repaired to start the detection of local seismic events. Two different approaches for detection were applied for stations located in Poland. One used standard STA/LTA triggers (Carl Johnson's STA/LTA algorithm) and grid search to classify and locate events. Result was manually verified. Other approach used Real Time Recurrent Network (RTRN) detection (Wiszniowski et al, 2014). Both methods gave similar results showing four previously unknown seismic events located in area of Gulf Of Gdańsk in southern Baltic Sea. The investigation of local seismicity is a good opportunity for verification of new seismic models of lithosphere in the area. In this paper we discuss both detection methods with their pros and cons (accuracy, efficiency, manual work required, scalability). We also show details of all detected and previously unknown events in discussed area. This work was partially supported by NCN grant UMO-2011/01/B/ST10/06653.

  10. Crustal Structure of the Southern Margin of the African Continent: Results from Geophysical Experiments.

    NASA Astrophysics Data System (ADS)

    Stankiewicz, J.; Parsiegla, N.; Ryberg, T.; Gohl, K.; Weckmann, U.; Trumbull, R.; Weber, M.

    2009-04-01

    A number of geophysical onshore and offshore experiments were carried out along a profile across the southern margin of the African Plate in the framework of the Inkaba yeAfrica project. Refraction seismic experiments show that Moho depth decreases rapidly from over 40 km inland to around 30 km at the present coast, before gently thinning out towards the Agulhas-Falkland Fracture Zone, which marks the transition zone between continental and oceanic crust. In the region of the abruptly decreasing Moho depth, in the vicinity of the boundary between the Namaqua-Natal Mobile Belt and the Cape Fold Belt, lower crustal P-wave velocities up to 7.4 km/s are observed. This is interpreted as metabasic lithologies of Precambrian age in the Namaqua-Natal Mobile Belt, or mafic intrusions added to the base of the crust by younger magmatism. The velocity model for the upper crust has excellent resolution. It is consistent with the known geological record, and also reveals a number of new features. These include a high velocity anomaly north of the centre of the Beattie Magnetic Anomaly. A joint interpretation of the velocity model with an electrical conductivity model, obtained from magnetotelluric studies, makes it possible to correlate this feature with a highly resistive body. Furthermore, a synclinal low velocity feature was identified in the Mesoproterozoic basement beneath the front of the Cape Fold Belt, south of the above mentioned feature. The northern edge of this feature correlates with the second magnetic body necessary to account for the BMA's signature.

  11. Field experiment in Soultz-sous-Forêts, 1993: Changes of the pattern of induced seismicity

    NASA Astrophysics Data System (ADS)

    Smirnov, Vladimir; Ponomarev, Alexander; Bernard, Pascal; Bourouis, Seid

    2013-12-01

    The data of the known field experiment on water injection in the borehole were analyzed. Parameters of self-similarity of seismicity were estimated in comparison with the changes of water pressure. Changes of seismicity parameters that indicate the redistribution of the failure from lower scales to upper are revealed. The total number of earthquakes per series of the water initiation found to be depended exponentially on the water pressure and seismic activity maximum is delayed gradually relative to beginning of initiation. The growth of induced seismicity zone in time differs from diffusion model for water flow in the porous medium. Analysis carried out from laboratory data indicates that diffusion growth of the failure area may be realized in the dry specimen, without fluid. It could be assumed that both kinetic processes — water and the failure diffusion — can be significant for the development of seismicity induced by the water injection.

  12. Recent Seismic Experiments of OBS in the South China Sea

    NASA Astrophysics Data System (ADS)

    Ruan, A.; Li, J.; Wu, Z.

    2012-12-01

    Since 2006 some research institutions of China have carried out some important seismic experiments by using ocean bottom seismometer(OBS) in the South China Sea (SCS) and obtained many concrete progresses in modeling the crustal structure of SCS and also in understanding of its formation and evolution as well. In 2006 three wide-angle profiles were completed in the northern margin, named OBS2006-1 across the northwestern sub-basin, OBS2006-2 parallel to the sea basin boundary and OBS2006-3 across the Dongsha Rise and Chaoshan Depression respectively. In 2010 two wide- angle profiles were completed, named OBS2010-1 and OBS 2010-2 both perpendicular to the northern off-shore faulting system. During 2009-2011 four wide-angle profiles were completed in the southern margin, named OBS973-1 from southern margin to the southwestern sub-basin, OBS973-2 from Liyue Bank to the southwestern sub-basin and OBS973-3 from Xisha to the southwestern sub-basin, OBS2011-2 from Xisha to Hainan Island respectively. In 2011 two 3D seismic array of OBS were completed in the Zhongnan-Changlong sea mount chain and Huangyan-Zhenbei sea mount chain respectively. Here we present some primary but important results as follows. (1) The velocity model of OBS2006-1 indicates that the crust under the continental slope decreases from 21km to 11km, and to 7.7km in the northwestern sub-basin with Moho depth ascends from 21km to 11km. The tectonic geometry and velocity structure of the northwestern sub-basin and its margins on both sides shows symmetrical and conjugate and indicates pure shear mode of continental margin rifting mechanism. (2) The velocity model of OBS2006-3 reveals remarkable thickness with maximum 8 km of the Mesozoic sediment in Chaoshan Depression in which velocity increases downward from 4.4 km/s at top to 5.3 km/s at the bottom. The buried depth of Moho decreases from 24-25 km under Dongsha Rise to 17 km in the lower slope and an obviously velocity abnormal is detected in the upper

  13. Seismic Images of the Gulf Stream Front off the Coast of North Carolina from the 2014 ENAM Community Seismic Experiment

    NASA Astrophysics Data System (ADS)

    Blacic, T. M.

    2014-12-01

    The Eastern North America Margin (ENAM) Community Seismic Experiment (CSE) is scheduled to collect on- and offshore active source seismic data including more than 2500 km of multichannel seismic (MCS) reflection profiles in the fall of 2014. The project was designed to address a wide array of questions related to the evolution and modification of the eastern North American rifted margin in conjunction with the arrival of the Earthscope transportable array on the US East Coast. The planned rifting-parallel profiles north and south of Cape Hatteras are expected to cross the front between the warm water of the Gulf Stream western boundary current and colder North Atlantic water providing the opportunity to image mesoscale features related to the front and their associated fine structure. Standard MCS data has been shown to be well-tuned to image ocean fine structure resulting from abrupt vertical changes in temperature and salinity in the ocean. Thus, the same seismic data that is collected to investigate the sub-seafloor geology can also be processed to image reflections in the water that reveal ocean processes with a horizontal resolution of ~10 m and vertical resolution of ~4 m. As an add-on to the ENAM CSE, 30 additional expendable bathythermographs and 3 conductivity temperature depth probes belonging to the University of Wyoming are planned for deployment during the collection of the MCS profiles resulting in an average hydrographic profile spacing of ~33 km. We present a first look at this new seismic oceanography data set providing 2-D images of ocean acoustic reflectivity correlated with closely spaced hydrographic measurements across the Gulf Stream front.

  14. DEVELOPING AND EXPLOITING A UNIQUE SEISMIC DATA SET FROM SOUTH AFRICAN GOLD MINES FOR SOURCE CHARACTERIZATION AND WAVE PROPAGATION

    SciTech Connect

    Julia, J; Nyblade, A A; Gok, R; Walter, W R; Linzer, L; Durrheim, R

    2008-07-08

    In this project, we are developing and exploiting a unique seismic data set to address the characteristics of small seismic events and the associated seismic signals observed at local (< 200 km) and regional (< 2000 km) distances. The dataset is being developed using mining-induced events from 3 deep gold mines in South Africa recorded on inmine networks (< 1 km) comprised of tens of high-frequency sensors, a network of 4 broadband stations installed as part of this project at the surface around the mines (1-10 km), and a network of existing broadband seismic stations at local/regional distances (50-1000 km) from the mines. After 1 year of seismic monitoring of mine activity (2007), over 10,000 events in the range -3.4 < ML < 4.4 have been catalogued and recorded by the in-mine networks. Events with positive magnitudes are generally well recorded by the surface-mine stations, while magnitudes 3.0 and larger are seen at regional distances (up to {approx}600 km) in high-pass filtered recordings. We have analyzed in-mine recordings in detail at one of the South African mines (Savuka) to (i) improve on reported hypocentral locations, (ii) verify sensor orientations, and (iii) determine full moment tensor solutions. Hypocentral relocations on all catalogued events have been obtained from P- and S-wave travel-times reported by the mine network operator through an automated procedure that selects travel-times falling on Wadati lines with slopes in the 0.6-0.7 range; sensor orientations have been verified and, when possible, corrected by correlating P-, SV-, and SH-waveforms obtained from theoretical and empirical (polarization filter) rotation angles; full moment tensor solutions have been obtained by inverting P-, SV-, and SH- spectral amplitudes measured on the theoretically rotated waveforms with visually assigned polarities. The relocation procedure has revealed that origin times often necessitate a negative correction of a few tenths of second and that hypocentral

  15. Leadership Development and the African American Male College Student Experience

    ERIC Educational Resources Information Center

    Oaks, D'Arcy John; Duckett, Kirstan; Suddeth, Todd; Kennedy-Phillips, Lance

    2013-01-01

    Qualitative interviews were employed to assess the effectiveness of a leadership program geared toward African American male personal and professional development, and to examine the relationship between program participation and connectedness. Elements of both social engagement (mentoring and being mentored, peer-to-peer relationships, and…

  16. Immersion and Identity: Experiences of an African American Preschool Child

    ERIC Educational Resources Information Center

    McCullough, Ruanda Garth; Reyes, Sharon Adelman

    2010-01-01

    This article explores the benefits and challenges of a Spanish language immersion preschool from the perspective of a non-Spanish speaking African American family. Data explored include the decision to enroll, reactions from peers and family, home-school communication issues, language development, and family involvement. In addition,…

  17. Exploration of the Lived Experiences of Illiterate African American Adults

    ERIC Educational Resources Information Center

    Waters, LaTonya Michell

    2009-01-01

    This phenomenological study examined the stories of illiterate African American adults to determine the factors that led to their illiteracy. Narrative techniques were utilized to discern themes from narrative accounts of eight participants. The participants were enrolled in one of two adult basic education programs referred to as ABE I and ABE…

  18. The South African Experience: Beyond the CIDA Model

    ERIC Educational Resources Information Center

    Bruton, John M.

    2008-01-01

    The Community and Individual Development Association (CIDA) City Campus is presented by Heaton as an innovative African alternative to traditional business education. However, he considers the model in isolation from the unique educational and economic circumstances of postapartheid South Africa. As a response, this article goes beyond the CIDA…

  19. A strategy for implementation of experience based seismic equipment qualification in IEEE and ASME industry standards

    SciTech Connect

    Adams, T.M.

    1996-12-01

    In the past 20 years, extensive data on the performance of mechanical and electric equipment during actual strong motion earthquakes and seismic qualification tests has been accumulated. Recognizing that an experience based approach provides a technically sound and cost effective method for the seismic qualification of some or certain equipment, the IEEE Nuclear Power Engineering Committee and the ASME Committee on Qualification of Mechanical Equipment established a Special Working Group to investigate the incorporation of experienced based methods into the industry consensus codes and standards currently used in the seismic qualification of Seismic Category Nuclear Power Plant equipment. This paper presents the strategy (course of action) which was developed by the Special Working Group for meeting this objective of incorporation of experience based seismic qualification standards used in the design and seismic qualification of seismic category nuclear power plant equipment. This strategy was recommended to both chartering organizations, the IEEE Nuclear Power Engineering Committee and the ASME Committee on Qualification of Mechanical Equipment for their consideration and implementation. The status of the review and implementation of the Special Working Group`s recommended strategy by the sponsoring organization is also discussed.

  20. Study of Local Seismic Events in Lithuania and Adjacent Areas Using Data from the PASSEQ Experiment

    NASA Astrophysics Data System (ADS)

    Janutyte, Ilma; Kozlovskaya, Elena; Motuza, Gediminas

    2013-05-01

    The territory of Lithuania and adjacent areas of the East European Craton have always been considered a region of low seismicity. Two recent earthquakes with magnitudes of more than 5 in the Kaliningrad District (Russian Federation) on 21 September 2004 motivated re-evaluation of the seismic hazard in Lithuania and adjacent territories. A new opportunity to study seismicity in the region is provided by the PASSEQ (Pasive Seismic Experiment) project that aimed to study the lithosphere-asthenosphere structure around the Trans-European Suture Zone. Twenty-six seismic stations of the PASSEQ temporary seismic array were installed in the territory of Lithuania. The stations recorded a number of local and regional seismic events originating from Lithuania and adjacent areas. This data can be used to answer the question of whether there exist seismically active tectonic zones in Lithuania that could be potentially hazardous for critical industrial facilities. Therefore, the aim of this paper is to find any natural tectonic seismic events in Lithuania and to obtain more general view of seismicity in the region. In order to do this, we make a manual review of the continuous data recorded by the PASSEQ seismic stations in Lithuania. From the good quality data, we select and relocate 45 local seismic events using the well-known LocSAT and VELEST location algortithms. In order to discriminate between possible natural events, underwater explosions and on-shore blasts, we analyse spatial distribution of epicenters and temporal distribution of origin times and perform both visual analysis of waveforms and spectral analysis of recordings. We show that the relocated seismic events can be grouped into five clusters (groups) according to their epicenter coordinates and origin and that several seismic events might be of tectonic origin. We also show that several events from the off-shore region in the Baltic Sea (at the coasts of the Kaliningrad District of the Russian Federation) are

  1. Reduce seismic design conservatism through large-scale earthquake experiments

    SciTech Connect

    Tang, H.T.; Stepp, J.C. )

    1992-01-01

    For structures founded on soil deposits, the interaction between the soil and the structure caused by incident seismic waves modifies the foundation input motion and the dynamic characteristics of the soil-structure system. This paper reports that as a result, soil-structure interaction (SSI) plays a critical role in the design of nuclear plant structures. Recognizing that experimental validation and quantification is required, two scaled cylindrical reinforced-concrete containment models (1/4-scale and 1/12-scale of typical full-scale reactor containments) were constructed in Lotung, an active seismic region in Taiwan. Forced vibration tests (FBT) were also conducted to characterize the dynamic behavior of the soil-structure system. Based on these data, a series of round-robin blind prediction and post-test correlation analyses using various currently-available SSI methods were performed.

  2. Las Vegas Basin Seismic Response Project: Preliminary Results From Seismic Refraction Experiments, Las Vegas, NV.

    NASA Astrophysics Data System (ADS)

    Zaragoza, S. A.; Snelson, C. M.; Harder, S. H.; Kaip, G.; Luke, B.; Buck, B. J.; Hanson, A. D.

    2002-12-01

    In May and September 2002, seismic refraction data were acquired in the Las Vegas basin. Located in the southern Basin and Range province, the cities of Las Vegas, North Las Vegas, and Henderson sit atop a fault-bounded basin with a depth of up to 5 km and basin dimensions of roughly 60 km wide (east-west) by 50 km in length (north-south). Previous isostatic gravity, seismic reflection, and aeromagnetic studies indicate that a series of sub-basins exist beneath the unconsolidated basin fill, with the deepest sub-basin occurring 5 km west of the fault block bounding the eastern edge of the basin (Frenchman Mountain). The basin is significantly deeper along its northern extremity, following the path of the fault block bounding the northern edge of the basin (Las Vegas Valley Shear Zone), and along the western edge of Frenchman Mountain. Recent, paleoseismic studies have indicated that faults in the Las Vegas region have the potential for an earthquake of M6.5 to 7.0. It is estimated that a M6.9 earthquake in the basin could produce about 11 billion dollars in damage and a significant number of deaths and/or injuries. In addition, an equivalent or larger event in the Death Valley fault zone, 150 km distance, would also be devastating to the metropolitan area of approximately 1.5 million residents. Therefore, it is essential to understand the seismic hazard posed to the Las Vegas region. This project is part of a larger collaborative effort to characterize the basin and its response to ground shaking. The University of Nevada, Las Vegas with assistance from the University of Texas at El Paso, students from UNLV and UTEP, volunteers from the community and several students from Centennial High school deployed 432 portable seismic recorders ("Texans") throughout the valley. Shot point locations were located at three quarries in the valley, one to the north, one to the east and one to the southwest. The profiles cross the Las Vegas Valley Shear zone as well as a prominent

  3. Extension and Basin Evolution of the East Kivu Graben, Rwanda, East African Rift: Results of New Multichannel Seismic Reflection Imaging

    NASA Astrophysics Data System (ADS)

    Scholz, C. A.; Zhang, X.; Wood, D.; Mburu, D.

    2012-12-01

    The East Kivu Graben resides within the eastern part of Lake Kivu, the highest Great Lake in the western branch of the East African Rift. The lake is more than 440 m deep in the East Kivu Basin, with a catchment comprised of Precambrian metasedimentary rocks and late-Cenozoic volcanics. Lake Kivu is renowned for its uniquely stratified water column, which is charged with considerable quantities of dissolved CO2 and methane, the former due to magmatic degassing. In February and March 2012 514 km of single- and multi-channel seismic reflection data were acquired in the Rwandan waters of Lake Kivu. The 24-fold multichannel seismic data were acquired aboard a modular research vessel, using a 600 m-long hydrophone streamer and single 40 cubic inch airgun. Extension in the East Kivu basin is largely accommodated along a major N-S striking, east-dipping boundary fault observed along the eastern edge of Iwawa Island, and extending for ~40 km along the length of the basin. Numerous intrabasinal normal faults occur to the east of the boundary fault, commonly displacing the lake floor and controlling the location of modern sublacustrine channels. The deepest sedimentary reflections observed on the new MCS data are 1.2-1.5 km below lake floor, near the center of the basin and boundary fault. Crystalline basement is not observed in these deepest areas however, suggesting the presence of a substantial sedimentary section below the imaged strata. Stratal surfaces dip steeply to the west over large areas of the half-graben basin. An acoustically transparent seismic sequence up to ~25 m thick is observed at the lake floor, which overlies a pronounced erosional unconformity over much of the basin. Some intrabasinal normal faults are draped by and do not penetrate the upper sequences, indicating several generations of fault activity in the basin. The late-Pleistocene exposure surface likely correlates to the previous lake level low stage that persisted prior to volcanic damming by

  4. Deep seismic exploration into the Arctic Lithosphere: Arctic-2012 Russian wide-angle seismic experiment

    NASA Astrophysics Data System (ADS)

    Kashubin, S.

    2013-12-01

    Integrated geological and geophysical studies of the Earth's crust and upper mantle (the Russian project 'Arctic-2012') were carried out in 2012 in the Mendeleev Rise, central Arctic. The set of studies included wide-angle seismic observations along the line crossing the Mendeleev Rise in its southern part. The DSS seismic survey was aimed at the determination of the Mendeleev Rise crust type. A high-power air gun (120 liters or 7320 cu.in) and ocean stations with multi-component recording (X, Y, Z geophone components and a hydrophone) were used for the DSS. The line was studied using a dense system of observation: bottom station spacing was from 10 to 20 km, excitation point spacing (seismic traces interval) was 315 m. Observation data were obtained in 27 location points of bottom stations, the distance between the first and the last stations was 480 km, the length of the excitation line was 740 km. In DSS wave fields, in the first and later arrivals, there are refracted and reflected waves associated with boundaries in the sedimentary cover, with the top of the basement, and with boundaries in the consolidated crust, including its bottom (Moho discontinuity). The waves could be traced for offsets up to 170-240 km. The DSS line coincides with the near-vertical CMP line worked out with the use of a 4500-m-long seismic streamer and with a 50 m shot point interval that allowed essential detalization of the upper part of the section and taking it into account in the construction of a deep crust model. The deep velocity model was constructed using ray-trace modeling of compressional, shear, and converted waves with the use of the SeisWide program. Estimates were obtained for Vp/Vs velocity ratios, which played an important role in determining the type of crust. The results of the interpretation show that the Mendeleev Rise section corresponds to sections of a thin continental crust of shelf seas and a thinned continental crust of submarine ridges and rises.

  5. Water percolation induced seismicity: evidences from low scale in-situ experiment

    NASA Astrophysics Data System (ADS)

    Saetta, V.; Amitrano, D.; Guglielmi, Y.; Senfaute, G.

    2003-04-01

    The aim of the paper is to investigate the correlation between the hydro-mechanical behaviour and the seismicity induced by hydraulic loading in a fractured rock mass. The experiments have been performed in a low scale fractured rock mass (1500 m3). The site is a small reservoir composed of a 17 m thick pile of Lower Cretaceous fractured limestone limited at the top and the bottom by a two-meter thick, impervious marl layer. A water-gate installed on the draining spring allows to artificially induce a 0.1 MPa hydraulic loading within the fracture network. Hydro - mechanical studies have pointed out different type of behaviour for rock joints thanks to punctual measurements of water pressure and deformations. The results of seismic monitoring show that the most permeable joints are aseismic whereas the low permeability joint revealed a mesurable seismicity related to water percolation. The fluid pressure increase induces instability phenomena at low scale like the rupture of crystallised zone, the formation of new micro-fractures or the sudden opening and the shearing of bedding joints. The seismic events display temporal clustering as observed for induced seismicity at larger scale (dam, gas reservoir). These results reveal that even for low water pressure variation (up to 0.1 MPa) hydraulical loading of a fractured rock masse can induce observable seismicity. These low scale (1-10 m) results could be of interest for understanding induced seismicity at larger scale (100-1000 m like dam, reservoir etc.).

  6. Experiences of African American Young Women in Science, Technology, Engineering, and Mathematics (STEM) Education

    NASA Astrophysics Data System (ADS)

    Kolo, Yovonda Ingram

    African American women are underrepresented in science, technology, engineering, and mathematics (STEM) fields throughout the United States. As the need for STEM professionals in the United States increases, it is important to ensure that African American women are among those professionals making valuable contributions to society. The purpose of this phenomenological study was to describe the experiences of African American young women in relation to STEM education. The research question for this study examined how experiences with STEM in K-10 education influenced African American young women's academic choices in their final years in high school. The theory of multicontextuality was used to provide the conceptual framework. The primary data source was interviews. The sample was composed of 11 African American young women in their junior or senior year in high school. Data were analyzed through the process of open coding, categorizing, and identifying emerging themes. Ten themes emerged from the answers to research questions. The themes were (a) high teacher expectations, (b) participation in extra-curricular activities, (c) engagement in group-work, (d) learning from lectures, (e) strong parental involvement, (f) helping others, (g) self-efficacy, (h) gender empowerment, (i) race empowerment, and (j) strategic recruitment practices. This study may lead to positive social change by adding to the understanding of the experiences of African American young women in STEM. By doing so, these findings might motivate other African American young women to pursue advanced STEM classes. These findings may also provide guidance to parents and educators to help increase the number of African American women in STEM.

  7. Psychopathology, adversity, and creativity: diversifying experiences in the development of eminent African Americans.

    PubMed

    Damian, Rodica Ioana; Simonton, Dean Keith

    2015-04-01

    Symptoms associated with mental illness have been hypothesized to relate to creative achievement because they act as diversifying experiences. However, this theory has only been tested on predominantly majority-culture samples. Do tendencies toward mental illness still predict eminent creativity when they coexist with other diversifying experiences, such as early parental death, minority-status, or poverty? These alternative diversifying experiences can be collectively referred to as examples of developmental adversity. This conjecture was tested on a significant sample of 291 eminent African Americans who, by the nature of their status as long-term minorities, would experience more developmental adversity. Replicating majority-culture patterns, African American artists showed higher mental illness rates than African American scientists. Yet the absolute percentages were significantly lower for the African Americans, regardless of profession. Furthermore, mental illness predicted higher eminence levels only for the African American artists, an effect that diminished when controlling for developmental adversity. Because the latter predicted eminence for both artists and scientists, the "madness-to-genius" link probably represents just 1 of several routes by which diversifying experiences can influence eminence. The same developmental ends can be attained by different means. This inference warrants further research using other eminent creators emerging from minority culture populations. PMID:25090126

  8. African American women's experiences with physical activity in their daily lives.

    PubMed

    Nies, M A; Vollman, M; Cook, T

    1999-02-01

    Sedentary behavior is a major public health problem for African American women. A qualitative study used focus groups to explore African American women's experiences with physical activity in their daily lives. Women aged 35-50 were recruited to participate in the focus groups. Transcripts from the focus groups were coded and analyzed. African American women's facilitators of physical activity were daily routine, practical and convenient activities, personal safety, child care, weight loss, stress reduction, knowledge and commitment, enjoyment, pets, family and peer support, home and work facilities, and daylight and climate conditions. Barriers to physical activity were lack of child care, no person to exercise with, competing responsibilities, lack of space in the home, inability to use exercise facilities at work, lack of motivation, fatigue, and unsafe neighborhood. This information will provide the basis for generating new strategies to increase physical activity for African American women in the community. PMID:10074819

  9. We fall down: the African American experience of coping with the homicide of a loved one.

    PubMed

    Sharpe, Tanya L; Boyas, Javier

    2011-01-01

    Rates of homicide among African Americans are much higher than those of other racial or ethnic groups. Research has demonstrated that homicide can be psychologically debilitating for surviving family members. Yet, exploring the experiences of homicide victims’ surviving loved ones has received little attention. This study examined the coping strategies of African American survivors of homicide. Qualitative interviews were conducted with 8 African American family members (ages 18-82) of homicide victims. Survivors were recruited from the Massachusetts Office of Victim Services and from homicide survivor support, school, and community groups throughout the New England area. Interviews were conducted using open-ended questions derived from coping, support network, grief, and bereavement literatures. Results indicate that the primary coping strategies utilized by African American survivors of homicide victims are spiritual coping and meaning making, maintaining a connection to the deceased, collective coping and caring for others, and concealment. Implications for research and practice are discussed. PMID:22073426

  10. The Lived Experiences of African American Women with Breast Cancer: Implications for Counselors

    ERIC Educational Resources Information Center

    Clay, LaTasha K.

    2013-01-01

    Qualitative phenomenological methodology was used to explore the lived experiences of African American women diagnosed with breast cancer. Phenomenology focuses on the meaning of the lived experiences of individuals experiencing a concept, structure, or phenomenon (Creswell, 2007). The purpose of phenomenological research is to identify phenomena…

  11. Discrimination at School: Latino and African American Male High School Students' Experiences

    ERIC Educational Resources Information Center

    Wakefield, W. David; Fajardo, Gabriela

    2005-01-01

    This study investigated male Latino and African American adolescents' experiences with racial discrimination at school. Participants (N = 85) were recruited from an urban public high school in southern California. Students completed paper and pencil measures assessing their experiences with racial discrimination. Overall, Latino and African…

  12. Caregiver Experiences of Discrimination and African American Adolescents' Psychological Health over Time

    ERIC Educational Resources Information Center

    Ford, Kahlil R.; Hurd, Noelle M.; Jagers, Robert J.; Sellers, Robert M.

    2013-01-01

    The present study examined the effect of caregivers' experiences of racial discrimination on their adolescent children's psychological functioning among a sample of 264 African American dyads. Potential relations between caregiver discrimination experiences and a number of indicators of adolescents' (aged 12-17) psychological functioning over time…

  13. African American and European American Therapists' Experiences of Addressing Race in Cross-Racial Psychotherapy Dyads

    ERIC Educational Resources Information Center

    Knox, Sarah; Burkard, Alan W.; Johnson, Adanna J.; Suzuki, Lisa A.; Ponterotto, Joseph G.

    2003-01-01

    Using Consensual Qualitative Research, 12 licensed psychologists' overall experiences addressing race in psychotherapy were investigated, as were their experiences addressing race in a specific cross-racial therapy dyad. Results indicated that only African American psychologists reported routinely addressing race with clients of color or when race…

  14. The Experience of African Students Studying Nursing in the United States in Relation to Their Use of Critical Thinking

    ERIC Educational Resources Information Center

    Tyson, Donald Lee

    2012-01-01

    This qualitative study explores the critical thinking experiences of African nursing students enrolled in several universities in the U.S. Using a semi-structured interview approach, twelve African students discussed their experiences using and learning a western critical thinking approach, as well as described their educational experiences in…

  15. Structural evolution beneath Sakurajima Volcano, Japan, revealed through rounds of controlled seismic experiments

    NASA Astrophysics Data System (ADS)

    Tsutsui, Tomoki; Iguchi, Masato; Tameguri, Takeshi; Nakamichi, Haruhisa

    2016-04-01

    Structural evolution beneath an active volcano is detected as the variation of seismic reflectivity through controlled seismic experiments, which is interpreted as being associated with discharging magma. The target of the present study is Sakurajima Volcano, which is one of the most active volcanoes in Japan. Six rounds of seismic experiments with controlled sources have been conducted annually at the volcano. Two seismic reflection profiles are obtained from the datasets for each successful round of experiments. The experiments reveal clear annual variation in seismic reflectivity at a depth of 6.2 km in the northeastern part of Sakurajima. The reflectivity is maximum in December 2009 upon the first intrusion of magma and decreases gradually until December 2013, which coincides with the inflation and deflation cycle of Sakurajima Volcano. Reflectivity variation occurred in the embedded clear reflector at depth. An evolving sandwiched structure in the intermediate layer is used as the reflector model. Lower-velocity magma embedded in the intermediate layer and its succeeding velocity increment explain the variation range of reflectivity. This is interpreted as a temperature decrease associated with discharging magma at depth. The present study describes a new approach for instantaneously sensing magma properties and for monitoring active volcanoes.

  16. An active seismic experiment at Tenerife Island (Canary Island, Spain): Imaging an active volcano edifice

    NASA Astrophysics Data System (ADS)

    Garcia-Yeguas, A.; Ibañez, J. M.; Rietbrock, A.; Tom-Teidevs, G.

    2008-12-01

    An active seismic experiment to study the internal structure of Teide Volcano was carried out on Tenerife, a volcanic island in Spain's Canary Islands. The main objective of the TOM-TEIDEVS experiment is to obtain a 3-dimensional structural image of Teide Volcano using seismic tomography and seismic reflection/refraction imaging techniques. At present, knowledge of the deeper structure of Teide and Tenerife is very limited, with proposed structural models mainly based on sparse geophysical and geological data. This multinational experiment which involves institutes from Spain, Italy, the United Kingdom, Ireland, and Mexico will generate a unique high resolution structural image of the active volcano edifice and will further our understanding of volcanic processes.

  17. A Comparison of Seismicity Characteristics and Fault Structure Between Stick-Slip Experiments and Nature

    NASA Astrophysics Data System (ADS)

    Goebel, T. H. W.; Sammis, C. G.; Becker, T. W.; Dresen, G.; Schorlemmer, D.

    2015-08-01

    Fault zones contain structural complexity on all scales. This complexity influences fault mechanics including the dynamics of large earthquakes as well as the spatial and temporal distribution of small seismic events. Incomplete earthquake records, unknown stresses, and unresolved fault structures within the crust complicate a quantitative assessment of the parameters that control factors affecting seismicity. To better understand the relationship between fault structure and seismicity, we examined dynamic faulting under controlled conditions in the laboratory by creating saw-cut-guided natural fractures in cylindrical granite samples. The resulting rough surfaces were triaxially loaded to produce a sequence of stick-slip events. During these experiments, we monitored stress, strain, and seismic activity. After the experiments, fault structures were imaged in thin sections and using computer tomography. The laboratory fault zones showed many structural characteristics observed in upper crustal faults, including zones of localized slip embedded in a layer of fault gouge. Laboratory faults also exhibited a several millimeter wide damage zone with decreasing micro-crack density at larger distances from the fault axis. In addition to the structural similarities, we also observed many similarities between our observed distribution of acoustic emissions (AEs) and natural seismicity. The AEs followed the Gutenberg-Richter and Omori-Utsu relationships commonly used to describe natural seismicity. Moreover, we observed a connection between along-strike fault heterogeneity and variations of the Gutenberg-Richter b value. As suggested by natural seismicity studies, areas of low b value marked the nucleation points of large slip events and were located at large asperities within the fault zone that were revealed by post-experimental tomography scans. Our results emphasize the importance of stick-slip experiments for the study of fault mechanics. The direct correlation of

  18. Experiences of African Students in Predominantly White Institutions: A Literature Overview.

    PubMed

    Inyama, Davis; Williams, Allison; McCauley, Kay

    2016-01-01

    The objective of this paper is to examine research conducted on the experiences of African health sciences students in predominantly white higher education institutions/environments. The main elements of cross-cultural adaptation models were adopted to discuss the amalgamated themes under the auspices of adjustment, integration, and conditioning. The overview revealed that African students encounter unique experiences, with isolation and "feeling different" being commonly mentioned. Recommendations for future research are presented, including programmatic implications for higher education and student affairs professionals. PMID:27525115

  19. Experiences of African Students in Predominantly White Institutions: A Literature Overview

    PubMed Central

    McCauley, Kay

    2016-01-01

    The objective of this paper is to examine research conducted on the experiences of African health sciences students in predominantly white higher education institutions/environments. The main elements of cross-cultural adaptation models were adopted to discuss the amalgamated themes under the auspices of adjustment, integration, and conditioning. The overview revealed that African students encounter unique experiences, with isolation and “feeling different” being commonly mentioned. Recommendations for future research are presented, including programmatic implications for higher education and student affairs professionals. PMID:27525115

  20. Large-N Seismic Deployment at the Source Physics Experiment (SPE) Site

    NASA Astrophysics Data System (ADS)

    Chen, T.; Snelson, C. M.; Mellors, R. J.; Pitarka, A.

    2015-12-01

    The Source Physics Experiment (SPE) is multi-institutional and multi-disciplinary project that consists of a series of chemical explosion experiments at the Nevada National Security Site. The goal of SPE is to understand the complicated effect of earth structures on source energy partitioning and seismic wave propagation, develop and validate physics-based monitoring, and ultimately better discriminate low-yield nuclear explosions from background seismicity. Deployment of a large number of seismic sensors is planned for SPE to image the full 3-D wavefield with about 500 three-component sensors and 500 vertical component sensors. This large-N seismic deployment will operate near the site of SPE-5 shot for about one month, recording the SPE-5 shot, ambient noise, and additional controlled-sources. This presentation focuses on the design of the large-N seismic deployment. We show how we optimized the sensor layout based on the geological structure and experiment goals with a limited number of sensors. In addition, we will also show some preliminary record sections from deployment. This work was conducted under Contract No. DE-AC52-06NA25946 with the U.S. Department of Energy.

  1. Academic attainment and the high school science experiences among high-achieving African American males

    NASA Astrophysics Data System (ADS)

    Trice, Rodney Nathaniel

    This study examines the educational experiences of high achieving African American males. More specifically, it analyzes the influences on their successful navigation through high school science. Through a series of interviews, observations, questionnaires, science portfolios, and review of existing data the researcher attempted to obtain a deeper understanding of high achieving African American males and their limitations to academic attainment and high school science experiences. The investigation is limited to ten high achieving African American male science students at Woodcrest High School. Woodcrest is situated at the cross section of a suburban and rural community located in the southeastern section of the United States. Although this investigation involves African American males, all of whom are successful in school, its findings should not be generalized to this nor any other group of students. The research question that guided this study is: What are the limitations to academic attainment and the high school science experiences of high achieving African American males? The student participants expose how suspension and expulsion, special education placement, academic tracking, science instruction, and teacher expectation influence academic achievement. The role parents play, student self-concept, peer relationships, and student learning styles are also analyzed. The anthology of data rendered three overarching themes: (1) unequal access to education, (2) maintenance of unfair educational structures, and (3) authentic characterizations of African American males. Often the policies and practices set in place by school officials aid in creating hurdles to academic achievement. These policies and practices are often formed without meaningful consideration of the unintended consequences that may affect different student populations, particularly the most vulnerable. The findings from this study expose that high achieving African American males face major

  2. Development of performance criteria for advanced Viking seismic experiments

    NASA Technical Reports Server (NTRS)

    1972-01-01

    The characteristics and requirements of the seismic instrument for mapping the internal structure of the planet Mars are briefly described. The types of signals expected to exist are microseismic background generated by wind and pressure variations and thermal effects, disturbances of or in the landed vehicle, signals caused by faulting and volcanic activity, and signals due to meteoritic impacts. The advanced instrument package should include a short-period vertical component system, a long-period or wide-band 3-component system, a high frequency vertical component system, and a system for detection and rejection of lander noises. The Viking '75, Surveyor, and Apollo systems are briefly described as potential instruments to be considered for modification. Data processing and control systems are also summarized.

  3. Recording and investigation of the seismic signal generated by hypervelocity impact experiments and numerical models

    NASA Astrophysics Data System (ADS)

    Güldemeister, N.; Moser, D.; Wünnemann, K.; Hoerth, T.; Schäfer, F.

    2013-09-01

    Meteorite impacts can cause environmental consequences, one of which is the generation of ground motions that may exceed the magnitude of the largest earthquakes [1]. Impacts generate shock waves that attenuate with distance until they even tually turn into seismic waves. Thus, meteorite impact may be considered as a source for seismic shaking similar to earthquakes. Seismic signals have been recorded in explosion experiments [2] and in hydrocode models of large impact events such as the Chicxulub crater [3]. To determine how much of the kinetic energy Ekin of the impactoris turned into seismic energy Eseis can be investigated experimentally (by recording the acoustic emission) or by numerical models. The ratio of Eseis/Ekin is the so called seismic efficiency k. The seismic efficiency depends on material properties (porosity) and is usually estimated to range between 10-2 and 10-6 [2,4]. In the framework of the "MEMIN" (multidisciplinary experimental and modeling impact crater research network) project a suite of hypervelocity impact experiments on a decimeter scale have been carried out [5]. We use acoustic emission (AE) technique and pressure gauges in high spatiotemporal Meteorite impacts can cause environmental consequences, one of which is the generation of ground motions that may exceed the magnitude of the largest earthquakes [1]. Impacts generate shock waves that attenuate with distance until they even tually turn into seismic waves. Thus, meteorite impact may be considered as a source for seismic shaking similar to earthquakes. Seismic signals have been recorded in explosion experiments [2] and in hydrocode models of large impact events such as the Chicxulub crater [3]. To determine how much of the kinetic energy Ekin of the impactoris turned into seismic energy Eseis can be investigated experimentally (by recording the acoustic emission) or by numerical models. The ratio of Eseis/Ekin is the so called seismic efficiency k. The seismic efficiency depends

  4. Peru Subduction Zone Seismic Experiment (PeruSZE): Preliminary Results From a Seismic Network Between Mollendo and Lake Titicaca, Peru.

    NASA Astrophysics Data System (ADS)

    Guy, R.; Stubailo, I.; Skinner, S.; Phillips, K.; Foote, E.; Lukac, M.; Aguilar, V.; Tavera, H.; Audin, L.; Husker, A.; Clayton, R.; Davis, P. M.

    2008-12-01

    This work describes preliminary results from a 50 station broadband seismic network recently installed from the coast to the high Andes in Peru. UCLA's Center for Embedded Network Sensing (CENS) and Caltech's Tectonic Observatory are collaborating with the IRD (French L'Institut de Recherche pour le Developpement) and the Institute of Geophysics, in Lima Peru in a broadband seismic experiment that will study the transition from steep to shallow slab subduction. The currently installed line has stations located above the steep subduction zone at a spacing of about 6 km. In 2009 we plan to install a line of 50 stations north from this line along the crest of the Andes, crossing the transition from steep to shallow subduction. A further line from the end of that line back to the coast, completing a U shaped array, is in the planning phase. The network is wirelessly linked using multi-hop network software designed by computer scientists in CENS in which data is transmitted from station to station, and collected at Internet drops, from where it is transmitted over the Internet to CENS each night. The instrument installation in Peru is almost finished and we have been receiving data daily from 10 stations (out of total 50) since June 2008. The rest are recording on-site while the RF network is being completed. The software system provides dynamic link quality based routing, reliable data delivery, and a disruption tolerant shell interface for managing the system from UCLA without the need to travel to Peru. The near real-time data delivery also allows immediate detection of any problems at the sites. We are building a seismic data and GPS quality control toolset that would greatly minimize the station's downtime by alerting the users of any possible problems.

  5. Community among African American Students on Small, Predominantly White Campuses: The Unforeseen "Minority within a Minority" Experience.

    ERIC Educational Resources Information Center

    Littleton, Robert A.

    2003-01-01

    Describes the experiences of 16 African American students who attended four small, predominantly White colleges in the Southern Appalachian region of the United States. The African American community at these small colleges can sometimes be an unforeseen cultural experience especially for Black male and female nonathletes. Qualitative methodology…

  6. African American Women Coping with the Lived Experiences of Limited Mental Healthcare Access in Rural North Carolina

    ERIC Educational Resources Information Center

    Lesane, Everick S.

    2013-01-01

    This study examined the impact of lived experiences among African American women with limited mental healthcare access in rural North Carolina. The research examined how those lived experiences-due to limited transportation, low socioeconomic status, and limited healthcare access-further exacerbate emotional challenges among African American…

  7. The Lived Experience of the Adult African American Female Who Has Lived in Multiple Foster Care Placements

    ERIC Educational Resources Information Center

    Johnson, Avonda C.

    2012-01-01

    The purpose of the study was to examine and describe the lived experiences of the adult African American woman who had lived in multiple foster care placements. Eleven adult African American women ages 22-25 participated in semi-structured, face-to-face interviews to tell their stories and provide data of the memories of the experience. The…

  8. Striving to Be "in" the Profession and "of" It: The African American Experience in Physical Education and Kinesiology

    ERIC Educational Resources Information Center

    Wiggins, David K.; Wiggins, Brenda P.

    2011-01-01

    This study analyzes the experiences of African Americans in the physical education and kinesiology profession since the late 1850s. Using a variety of primary and secondary source material, we place special emphasis on the experiences of African American physical educators in higher education and in the American Alliance for Health, Physical…

  9. A wide-angle seismic survey of the Hecataeus Ridge, south of Cyprus: a microcontinental block from the African plate docked in a subduction zone?

    NASA Astrophysics Data System (ADS)

    Rahimi, Ayda; Welford, Kim; Hall, Jeremy; Hübscher, Christian; Louden, Keith; Ehrhardt, Axel

    2013-04-01

    Cyprus lies at the southern edge of the Aegean-Anatolian microplate, caught in the convergence of Africa and Eurasia. Subduction of the African plate below Cyprus has probably ceased and this has been attributed to the docking in the subduction zone of the Eratosthenes Seamount microcontinental fragment on the northern edge of the African plate. In early 2010, on R.V. Maria S. Merian, we conducted a wide-angle seismic survey to test the hypothesis that the Hecataeus Ridge, another possible microcontinental block lying immediately offshore SE Cyprus, might be related to an earlier docking event. The upper crust of southern Cyprus is dominated by ophiolites, with seismic velocities of up to 7 km s-1. A wide angle seismic profile along Hecataeus Ridge was populated with 15 Canadian and German ocean-bottom seismographs at 5 km intervals and these recorded shots from a 6000 cu. in. air gun array, fired approximately every 100 m. Rough topography of the seabed has made picking of phases and their modelling a demanding task. Bandpass and coherency filtering have enabled us to pick phases out to around 80 km. Tomographic inversion of short-range first arrivals provided an initial model of the shallow sub-seabed structure. Forward modelling by ray-tracing, using the code of Zelt and Smith, was then used to model crustal structure down to depths of around 20 km, with occasional evidence of reflections from deeper boundaries (Moho?). Modelling results provide good control on P-wave velocities in the top 20 km and some indications of deeper events. There is no evidence of true velocities approaching 7 km/s in the top 20 km below the Ridge that might indicate the presence of ophiolitic rocks. Regional gravity and magnetic field data tend to support this proposition. We thus conclude that Hecataeus Ridge is not composed of characteristically ophiolitic, Cyprus (upper plate) crust, and it might well be derived from the African (lower) plate.

  10. Resilience Post Tenure: The Experience of an African American Woman in a PWI

    ERIC Educational Resources Information Center

    Behar-Horenstein, Linda S.; West-Olatunji, Cirecie A.; Moore, Thomas E.; Houchen, Deidre F.; Roberts, Kellie W.

    2012-01-01

    The purpose of this study was: 1) to explore the pre-tenure experiences of an African American female faculty member in a counselor education program; and 2) to compare the themes that ascended from a precursor study to the current one. By using critical ethnography and case study format, this research gave voice to the participant by prompting…

  11. Racial Identity, Language Attitudes and Educational Experiences: The Voices of African American College Students

    ERIC Educational Resources Information Center

    Stewart, Gail A.

    2012-01-01

    The current study examines the language attitudes, racial identity and educational experiences of 75 African American university and community college students. This study is motivated by the hypothesis that the power of language attitudes dictates, to a large extent, the language one speaks, which is intimately tied to one's sense of…

  12. Personal, Professional, and Sociocultural Experiences of African American Female School Leaders

    ERIC Educational Resources Information Center

    Robinson, Armentress D.

    2014-01-01

    The purpose of this phenomenological study was to explore and gain an in-depth understanding of the personal, professional, and sociocultural experiences of ten African American female school leaders serving as assistant principals, principals, and central office administrators in four suburban school districts in the southeast region of the…

  13. Problematic Situations Associated with Dating Experiences and Relationships among Urban African American Adolescents: A Qualitative Study

    ERIC Educational Resources Information Center

    Sullivan, Terri N.; Erwin, Elizabeth H.; Helms, Sarah W.; Masho, Saba W.; Farrell, Albert D.

    2010-01-01

    This qualitative study focused on the identification of problem situations associated with adolescent dating experiences and relationships, including those that placed youth at risk for dating violence perpetration or victimization. Interviews were conducted with 44 African American middle and high school students in an urban school system.…

  14. Relationships between Discretionary Time Activities, Emotional Experiences, Delinquency and Depressive Symptoms among Urban African American Adolescents

    ERIC Educational Resources Information Center

    Bohnert, Amy M.; Richards, Maryse; Kohl, Krista; Randall, Edin

    2009-01-01

    Using the Experience Sampling Method (ESM), this cross-sectional study examined mediated and moderated associations between different types of discretionary time activities and depressive symptoms and delinquency among a sample of 246 (107 boys, 139 girls) fifth through eighth grade urban African American adolescents. More time spent in passive…

  15. Rearticulating the Leadership Experiences of African American Women in Midlevel Student Affairs Administration

    ERIC Educational Resources Information Center

    Clayborne, Hannah L.; Hamrick, Florence

    2007-01-01

    This qualitative study of African American women holding midlevel administrative positions sought to broaden and challenge conceptualizations of leadership by focusing on respondents' descriptions of their leadership experiences. Findings centered principally on the intensely relational qualities associated with leadership and leading, mentoring…

  16. A Phenomenological Investigation of African American Counselor Education Students' Challenging Experiences

    ERIC Educational Resources Information Center

    Henfield, Malik S.; Woo, Hongryun; Washington, Ahmad

    2013-01-01

    This study explored 11 African American doctoral students' perceptions of challenging experiences in counselor education programs. The authors identified the following themes using critical race theory: feelings of isolation, peer disconnection, and faculty misunderstandings and disrespect. Implications for counselor education programs and…

  17. Gay and Lesbian Youth Experiences of Homophobia in South African Secondary Education

    ERIC Educational Resources Information Center

    Butler, A. H.; Alpaslan, A. H.; Strumpher, J.; Astbury, G.

    2003-01-01

    In post-apartheid South Africa, the tenets of inclusivity, nondiscrimination, and tolerance are actively encouraged and legislated across all sectors of society, including education. However, in examining the coming out experiences of 18 South African gay and lesbian youth (1997-2000), it became apparent that they had all experienced…

  18. Ring of Silence: African American Women's Experiences Related to Their Breasts and Breast Cancer Screening

    ERIC Educational Resources Information Center

    Thomas, Eileen

    2006-01-01

    The purpose of this study was to explore women's memories and feelings concerning their breasts and breast cancer screening experiences in relation to their current breast cancer screening behaviors. Twelve African American women shared stories that were generated in written narratives and individual interviews. Two core themes emerged from the…

  19. Toddler Feeding: Expectations and Experiences of Low-Income African American Mothers

    ERIC Educational Resources Information Center

    Horodynski, Mildred A.; Brophy-Herb, Holly; Henry, Michelle; Smith, Katharine A.; Weatherspoon, Lorraine

    2009-01-01

    Objective: To ascertain maternal expectations and experiences with mealtimes and feeding of toddlers among low-income African American mothers in two mid- to large-size cities in the United States. Design: Qualitative focus group study. Setting: Two Early Head Start programme sites in a Midwestern state which serve low income families. Method:…

  20. Mathematically Successful Sons: The Roles Perceptions, and Experiences of African American Parents

    ERIC Educational Resources Information Center

    Berry, Robert Q., III.

    2008-01-01

    The stories of four mathematically successful middle schools African American boys are used to describe the roles, perceptions, and experiences of their parents. The parents of played multiple roles for their sons: (a) guardians of opportunities, (b) standard setters, (c) resources for mathematical knowledge, and (d) models of success. As…

  1. Black South Africans in the United States: An Analysis of Their Educational and Practical Training Experiences.

    ERIC Educational Resources Information Center

    Crawford, Beth S.; Kreidle, Ann M.

    A study was done of the experiences of Black South Africans who came to the United States for education and training. The research studied 140 individuals who participated in two programs between 1980 and 1991. Data were collected from the student files and from standard university data from "Profiles of American Colleges" by Barron's Educational…

  2. Ethical issues in genomic research on the African continent: experiences and challenges to ethics review committees

    PubMed Central

    2014-01-01

    This is a report on a workshop titled ‘Ethics for genomic research across five African countries: Guidelines, experiences and challenges’, University of the Witwatersrand, Johannesburg, South Africa, 10 and 11 December 2012. The workshop was hosted by the Wits-INDEPTH partnership, AWI-Gen, as part of the H3Africa Consortium. PMID:25145346

  3. Barriers to Persistence in Adult Basic Education: The Experiences of African American Learners

    ERIC Educational Resources Information Center

    Thomas, Simone

    2011-01-01

    One of the most pervasive issues facing educators and administrators in Adult Basic Education (ABE) is student persistence. The purposes of this qualitative study were 1) to identify the experiences that African American adult learners associated with their decisions to leave ABE programs; 2) to ascertain the impact of participants'…

  4. Illuminating the Experiences of African-American Nursing Faculty Seeking Employment in Higher Education in Nursing

    ERIC Educational Resources Information Center

    Loyd, Vanessa

    2015-01-01

    This study explored and described the experience of female African-American nursing faculty seeking employment in higher education in nursing. The lack of diversity in the nursing workforce has been attributed as a major underlying cause of disparity in healthcare in the United States. The importance of increasing the number of minority nursing…

  5. African American Students in Counselor Education Programs: Perceptions of Their Experiences

    ERIC Educational Resources Information Center

    Henfield, Malik S.; Owens, Delila; Witherspoon, Sheila

    2011-01-01

    The authors explored 11 African American doctoral students' perceptions of their experiences in counselor education programs, and their findings are presented. Using a phenomenological methodological framework, the authors investigated the various systems of support that students use as they navigate their respective programs. Human agency was the…

  6. African American Students' Perceptions of Their High School Career Counseling Experiences

    ERIC Educational Resources Information Center

    Byrd, Leah A.

    2013-01-01

    This study examined the perceptions of 10 African American 12th-grade students from one suburban high school regarding their high school career counseling experiences. The purpose was to better understand how students perceive their career counseling interactions and to ascertain what factors were relevant in the counseling relationship. An…

  7. The Intersection of Race and Class in the South African University: Student Experiences

    ERIC Educational Resources Information Center

    Soudien, C.

    2008-01-01

    The purpose of this article is to make a contribution to the discussion on the sociological features of higher education and the significant ways in which it comes to produce a particular version of the racial experience. While work has appeared which has begun to comment on fragmentation of identity in South African higher education there is…

  8. In Their Own Voices: Adolescent African American Males' Experiences of the Achievement Gap

    ERIC Educational Resources Information Center

    Moon, Natasha S.; Singh, Anneliese A.

    2015-01-01

    The authors use a phenomenological research tradition grounded in CRT tenets to describe the daily lived experiences that 12 male African American youth had in relation to the achievement gap. Researchers collected individual semi-structured interviews and focus group data related to the study phenomenon. There were five themes identified in…

  9. Missed Opportunities: Examining the Literacy Experiences of African American Students Displaced by Hurricane Katrina

    ERIC Educational Resources Information Center

    Pollard, Tamica McClarty

    2011-01-01

    The purpose of this study was to examine how five African American middle school students, who were displaced by Hurricane Katrina represent their literacy experiences before, during, and after their displacement. Specifically, the two research questions were: (a) What are the stories that these middle school students tell about their lives,…

  10. African American College Students' Experience of Racial Discrimination and the Role of College Hassles

    ERIC Educational Resources Information Center

    Banks, Kira Hudson

    2010-01-01

    The current study examines the relationship between racial discrimination and depressive symptoms. In particular, it investigated whether college hassles moderated or mediated the relationship. Participants included 194 African American students from a large, Midwestern, state university. Participants provided self-report of their experience of…

  11. On the Outside Looking in: An African American Family's Experience in an Individualized Education Plan Meeting

    ERIC Educational Resources Information Center

    Angelov, Azure D. S.; Anderson, Sheri L.

    2012-01-01

    The current laws that mandate special education originated through the advocacy of families (Turnbull & Turnbull, 1990). Over the years, families have challenged the system to provide free and appropriate public educations for their children. We share, through qualitative measures, the experiences of one African American family and the educators…

  12. Underserved, Underrepresented, Unprepared: Experiences of African American Females in Community College with Barriers to Academic Success

    ERIC Educational Resources Information Center

    Jobe, LaWanda D.

    2013-01-01

    African American women are enrolling and returning to college in large numbers across many community college campuses, especially those women who would be characterized as nontraditional students. This qualitative study examined and analyzed the experiences, stresses, and coping mechanisms of first generation, nontraditional, single parent,…

  13. African-American School Counselors in Majority School Districts: A Qualitative Perspective of Their Lived Experiences

    ERIC Educational Resources Information Center

    Wingate, Crystal Nicole

    2011-01-01

    This dissertation will focus on the lived experiences of African-American school counselors in majority school districts and the lack of retention among this population. The lack of retention and representation of ethnic minorities in the workforce has been the subject of much discussion throughout the United States (Ingersoll, 2004). The…

  14. Educational Change in Post-Conflict Contexts: Reflections on the South African Experience 20 Years Later

    ERIC Educational Resources Information Center

    Christie, Pam

    2016-01-01

    Reflecting on South African experience, this paper develops an analytical framework using the work of Henri Lefebvre and Nancy Fraser to understand why socially just arrangements may be so difficult to achieve in post-conflict reconstruction. The paper uses Lefebvre's analytic to trace three sets of entangled practices…

  15. Elephant low-frequency vocalizations propagate in the ground and seismic playbacks of these vocalizations are detectable by wild African elephants (Loxodonta africana)

    NASA Astrophysics Data System (ADS)

    O'Connell-Rodwell, Caitlin E.; Wood, Jason D.; Gunther, Roland; Klemperer, Simon; Rodwell, Timothy C.; Puria, Sunil; Sapolsky, Robert; Kinzley, Colleen; Arnason, Byron T.; Hart, Lynette A.

    2001-05-01

    Seismic correlates of low-frequency vocalizations in African and Asian elephants propagate in the ground at different velocities, with the potential of traveling farther than their airborne counterparts. A semblance technique applied to linear moveouts on narrow-bandpass-filtered data, coupled with forward modeling, demonstrates that the complex waves observed are the interference of an air wave and a Rayleigh wave traveling at the appropriate velocities. The Rayleigh wave appears to be generated at or close to the elephant, either by coupling through the elephant's body or through the air near the body to the ground. Low-frequency elephant vocalizations were reproduced seismically and played back to both a captive elephant and to elephant breeding herds in the wild, monitoring the elephants' behavioral responses, spacing between herd members and time spent at the water hole as an index of heightened vigilance. Breeding herds detected and responded appropriately to seismically transmitted elephant warning calls. The captive studies promise to elucidate a vibrotactile threshold of sensitivity for the elephant foot. Elephants may benefit from the exploitation of seismic cues as an additional communication modality, thus expanding their signaling repertoire and extending their range of potential communication and eavesdropping beyond that possible with airborne sound.

  16. Joint seismic-geodynamic-mineral physical modelling of African geodynamics: A reconciliation of deep-mantle convection with surface geophysical constraints

    SciTech Connect

    Forte, A M; Quere, S; Moucha, R; Simmons, N A; Grand, S P; Mitrovica, J X; Rowley, D B

    2008-08-22

    Recent progress in seismic tomography provides the first complete 3-D images of the combined thermal and chemical anomalies that characterise the unique deep mantle structure below the African continent. With these latest tomography results we predict flow patterns under Africa that reveal a large-scale, active hot upwelling, or superplume, below the western margin of Africa under the Cape Verde Islands. The scale and dynamical intensity of this West African superplume (WASP) is comparable to that of the south African superplume (SASP) that has long been assumed to dominate the flow dynamics under Africa. On the basis of this new tomography model, we find the dynamics of the SASP is strongly controlled by chemical contributions to deep mantle buoyancy that significantly compensate its thermal buoyancy. In contrast, the WASP appears to be entirely dominated by thermal buoyancy. New calculations of mantle convection incorporating these two superplumes reveal that the plate-driving forces due to the flow generated by the WASP is as strong as that due to the SASP. We find that the chemical buoyancy of the SASP exerts a strong stabilising control on the pattern and amplitude of shallow mantle flow in the asthenosphere below the southern half of the African plate. The asthenospheric flow predictions provide the first high resolution maps of focussed upwellings that lie below the major centres of Late Cenozoic volcanism, including the Kenya domes and Hoggar massif that lies above a remnant plume head in the upper mantle. Inferences of sublithospheric deformation from seismic anisotropy data are shown to be sensitive to the contributions of chemical buoyancy in the SASP.

  17. Imaging the deep seismic structure beneath a mid-ocean ridge: the MELT experiment

    PubMed

    1998-05-22

    The Mantle Electromagnetic and Tomography (MELT) Experiment was designed to distinguish between competing models of magma generation beneath mid-ocean ridges. Seismological observations demonstrate that basaltic melt is present beneath the East Pacific Rise spreading center in a broad region several hundred kilometers across and extending to depths greater than 100 kilometers, not just in a narrow region of high melt concentration beneath the spreading center, as predicted by some models. The structure of the ridge system is strongly asymmetric: mantle densities and seismic velocities are lower and seismic anisotropy is stronger to the west of the rise axis. PMID:9596564

  18. An Idea for an Active Seismic Experiment on Mars in 2008

    NASA Technical Reports Server (NTRS)

    Lognonne, Ph.; Banerdt, B.; Giardini, D.; Costard, F.

    2001-01-01

    The detection of liquid water is of prime interest and should have deep implications in the understanding of the Martian hydrological cycle and also in exobiology. In the frame of the 2007 joint CNES-NASA mission to Mars, a set of 4 NETLANDERS developed by an European consortium is expected to be launched in June 2007. We propose to use a second spacecraft going or landing to Mars to release near one of the Netlander a series of artificial metallic meteorites, in order to perform an active seismic experiment providing a seismic profile of the crust and subsurface.

  19. Hand replantation: First experience in a sub-Saharan African country (Togo)

    PubMed Central

    Amouzou, Komla Sena; Amakoutou, Komla; Bakriga, Batarabadja; Abalo, Anani; Dossim, Assang

    2016-01-01

    Fifty years after Chen has performed the first forearm replantation, we report our first case of hand replantation in a sub-Saharan African country. The etiology of the amputation was machete due to interpersonal violence. The amputation was trans-carpal, guillotine-type, subtotal non-viable maintained with a small skin bridge. The replantation procedure was successful. At one year follow-up, the functional result according to Chen's criteria was excellent. Through this first experience, we can state that hand replantation can be performed successfully both in survival and function in a non-specialized hospital of a sub-Saharan African country. PMID:27274133

  20. African-American Women’s Perceptions and Experiences About Breastfeeding

    PubMed Central

    Obeng, Cecilia S.; Emetu, Roberta E.; Curtis, Terry J.

    2015-01-01

    There are health benefits to breastfeeding for both mothers and their children. The preventive health effects of breastfeeding continue into adulthood, lowering rate of various chronic illnesses. African-American women, especially of lower socioeconomic status, are less likely to breastfeed in comparison to their racial and ethnic counterparts. The purpose of this study is to explore how African-American women experience breastfeeding in the early stages of postpartum care. Two focus groups (N = 20, 10 in each group) were conducted with African-American mothers. Results revealed that participants felt that there were health benefits to breastfeeding, and organizations such as Women, Infants, and Children (WIC) provided support. However, participants stated that lack of information, negative perceptions, and unforeseen circumstances were barriers to breastfeeding. This study proposes support and interventions for this group to increase breastfeeding among this population. PMID:26734597

  1. Discriminatory Experiences and Depressive Symptoms among African American Women: Do Skin Tone and Mastery Matter?

    PubMed Central

    Lincoln, Karen D.; Taylor, Robert Joseph; Jackson, James S.

    2010-01-01

    We apply structural equation modeling techniques to data from the National Survey of American Life to investigate the relationship between perceived discrimination and depressive symptoms among African American women ages 18–98 years (N=2,299). In addition, we evaluate whether or not personal mastery accounts for the intensity of African American women’s psychological response to discrimination and whether or not exposure to discrimination varies by skin complexion. Findings reveal that discrimination is a major threat to African American women’s mental health. They are vulnerable to discrimination, in part, because discrimination undermines their beliefs in mastery making them less psychologically resilient. Experiences of discrimination do not differ by complexion. We conclude that complexion does not matter, but mastery does. PMID:21151821

  2. Seismicity location from analysis of a 2 years passive seismological experiment around Ulaanbaatar

    NASA Astrophysics Data System (ADS)

    Batkhuu, Battulga; Munkhuu, Ulziibat; Sebe, Olivier; Monfret, Tony; Deschamps, Anne; Gao, Mengtan; Wu, Qingju

    2014-05-01

    We analyse broadband seismological records from a 2 years temporary array deployed over a 400x600km2 region in central Mongolia, including Ulaanbaatar region, by a Sino-Mongolian cooperation. The dataset is completed with all available regional data, mostly recorded by Mongolian National Seismic Network (MNSN) operated by Research Center for Astronomy and Geophysics (RCAG). The seismic activity of the covered area is not very high, except SW of Ulaanbaatar. To obtain as good as possible image of this seismicity, we have first to determine a regional velocity model. The development of mining activity in Mongolia, allows us to record a large set of quarry blasts. Due to the very continental position of Mongolia, micro-seismic noise level is low and the signal of these human made sources are very often recorded at distances as far as 200km. Travel time information of direct, reflected and refracted waves are used to produce crustal information (Moho depth and mean crustal P wave velocity, and velocity below the Moho, Vp/Vs ratio) over the area of observation. We show that the crust of the studied area is relatively homogeneous which allows us to improve this very simple model, searching the best crustal model with Velest software. The experiment was supported by Sino-Mongolian joint project titled "The Geophysical Investigation and Deep Structure Modeling for Seismic Hazard Assessment in the Far East", Project code: 2011DFB20120.

  3. The Millikan shaking experiments and high-frequency seismic wave propagation in Southern California

    NASA Astrophysics Data System (ADS)

    Tanimoto, Toshiro; Okamoto, Taro

    2014-08-01

    In order to study high-frequency seismic wave propagation, seismic wavefields generated by resonant-shaking experiments of the Millikan Library, on the campus of California Institute Technology (Pasadena, California, USA), were analysed. Because the resonant shaking frequencies are 1.12 Hz (the east-west direction) and 1.64 Hz (the north-south direction), this active-source experiment can provide opportunities for studying high-frequency seismic wave propagation in Southern California. Because they are very narrow frequency band data, the analyses must be quite different from ordinary time-domain analyses. We show, theoretically, that the signals must be dominated by surface waves. Adopting this surface wave assumption, we proceed to make two separate analyses, one on spectral amplitude and the other on phase. We present a new method to derive group velocity from phase based on the cross correlations between the station in the Millikan Library (MIK) and stations in the regional network. Our results support that an active-source experiment by resonant shaking of a building is a feasible approach for high-frequency seismic wave studies.

  4. Seismic Properties of Partially Molten Rocks: Constraints from Experiments and Observations on Natural Rocks

    NASA Astrophysics Data System (ADS)

    Faul, U.; Jackson, I.; Garapic, G.

    2014-12-01

    The increasing resolution of seismic tomography studies as well as techniques that are sensitive to sharp, localized velocity changes indicate that melt is present in diverse tectonic settings in the upper mantle. Unresolved questions are the quantification of seismic velocities and attenuation to melt fraction, and the dynamic stability of this melt. Properties of partially molten rocks are generally sensitive to melt geometry. The melt geometry can be observed in experiments, but the experimental observations have to be extrapolated to mantle grain sizes. High resolution images of experimentally observed melt geometries (Garapic et al., 2013) indicate that the broad attenuation peak observed by forced torsional oscillation experiments (Jackson et al., 2004, Faul et al., 2004) are due to melt 'squirt'. Characterization of the inferred melt geometry in rocks recovered from mid-ocean ridges and peridotite massifs suggest that the experimental observations are applicable to the upper mantle. The data from the earlier seismic property experiments will be reprocessed with improved apparatus calibration and fitting strategies to provide a 'global' fit to the melt-bearing data as a function of grain size and melt fraction. This should allow quantification of the amount of melt imaged in seismic studies and therefore enable more accurate geodynamical models for example of arcs and backarcs, for which the highest resolution tomographic images exist. It should also provide more quantitative constraints on the amount of melt required to generate receiver functions and SS-bounces that suggest the presence of melt in the asthenosphere.

  5. Martian Ambient Seismic Noise: from the first modeling to the future data of the InSight Seismic experiment.

    NASA Astrophysics Data System (ADS)

    Lognonne, P. H.; Banerdt, W. B.; Mimoun, D.; Kobayashi, N.; Panning, M. P.; Pike, W. T.; Giardini, D.; Christensen, U. R.; Nishikawa, Y.; Murdoch, N.; Kawamura, T.; Kedar, S.; Spiga, A.

    2014-12-01

    The InSight NASA Discovery mission is expected to deploy a 3 axis VBB and a 3 axis SP seismometer on Mars by late september 2016. This seismic station will explore the Martian ambient noise, in addition to more classical science goals related to the detection of Marsquakes, Meteoritic Impacts and Tides. Mars, in contrast with the Earth (with both atmosphere and ocean) and the Moon (with no atmosphere nor ocean) is expected to have ambient noise only related to its atmosphere. Mars seismic data are therefore expecting to reveal the atmospheric coupling for a different atmospheric dynamics than Earth, especially in the 0.1-1 Hz bandwidth, dominated by oceanic microseisms on Earth. We rapidly present the expected performances of the SEIS experiment onboard InSight. This experiment is based on two 3 axis seismometers, one covering the tide and low seismic frequencies (up to 10 Hz) and a second one covering the high frequencies (from 0.1 Hz to 50 Hz). Both sensors are mounted on a sensors plateform, deployed by a robotic arm 1-2 meters from the lander and covered by thermal protection and a wind protection. The expected performances indicates that signal as low as 10**(-9) m/s**2/Hz**(1/2) will be detected in the 0.005-2 Hz bandwidth. We then focus on the modeling of this ambient atmospheric noise.This modeling has been done not only from constraints gathered by the atmospheric sensors of previous Mars missions (e.g. Viking and Pathfinder) but also by numerical modeling of the atmospheric perturbations, both at global scale and mesoscale. Theoretical estimation of the ambient noise has then been obtained for the pressure-correlated surface loading and the stochastic excitation of surface waves, at both long and very long period (e.g. Mars hum) and at medium or short period (e.g. regional and local generated surface waves). Results shows that most of these source of ambient noise will be detected, likely during the day for those generated locally and possibly during the

  6. ISIS : a formation flying ionospheric seismic imaging experiment

    NASA Astrophysics Data System (ADS)

    Mimoun, D.; Lognonné, Ph; Garcia, R.; Occhipinti, G.; Abbondanza, S.

    Today, available techniques for the lithosphere tomography are limited by the number of seismic stations that we can deploy : it is sometimes difficult to access to some remote regions, but foremost the number of stations that are deployable over the oceans is strongly reduced. If we can dispose of some sites on islands (which are all characterized by a strong background noise), and on the measurements on coastal areas borders, it is therefore difficult to inverse the fine structure of the oceanic lithosphere. A promising idea is to use a long known idea, that earthquakes have a measurable impact on the ionosphere. As a matter of fact, the decrease of the atmosphere density with respect to altitude implies an amplification of the Rayleigh waves in the atmosphere, up to a maximum at about 250 km. This effect has been quantified for the Denali earthquake (Ducic et al, 2003) though its impact on the TEC content on the ionosphere. We therefore propose to detect this effect from space, thanks to a spaceborne multistatic SAR. Our concept includes 3 satellites in formation (along the same orbit) in a MEO orbit (about 19000 km). The master satellite payload is a slightly modified SAR, which operates around two main frequencies, in order to allow the computation of the delay induced by ionospheric fluctuations. The two other satellites have a passive payload which is time-synchronized with the master SAR: the use of their crossing rays will allow a 3D reconstruction of the ionosphere. A preliminary design of the space segment proposes an implementation on a MEO-orbit compatible bus, with high peak power capabilities. In order to allow the compatibility of the payload concept with the on-board available power, we have assumed that the satellite will enter in its alert mode on ground request. When an earthquake occurs, we dispose of a ten minutes delay to "wake-up" the satellite. When not in alert mode, its nominal imaging frequency will be reduced to allow the detection of

  7. Tackling the African "poverty trap": the Ijebu-Ode experiment.

    PubMed

    Mabogunje, Akin L

    2007-10-23

    An experiment in poverty reduction began in 1998 in the city of Ijebu-Ode, Nigeria (estimated 1999 population 163,000), where, without the remittances from relatives abroad, an estimated 90% of the population lived below the poverty line of $1.00 (U.S.) per person per day. Central to the experiment was whether poverty can be dramatically reduced through a city consultation process that seeks to mobilize the entire community along with its diaspora. With 7 years of experience, the Ijebu-Ode experiment has been successful in many ways. There is increasing evidence that poverty in the city has been reduced significantly through the microfinancing of existing and new productive activities and the estimated >8,000 jobs these activities have created. Training based on both sustainability science and technology and indigenous practitioner knowledge has been a critical factor in the establishment of cooperatives and the development of new enterprises in specialty crops, small animal, and fish production. Much of this success has been possible as a result of harnessing social capital, especially through the dynamic leadership of the traditional authorities of the city and by the provision of ample loanable funds through the National Poverty Eradication Program of the federal government. The city consultation process itself engendered a participatory focus to the experiment from the beginning and has encouraged sustainability. Yet long-term sustainability is still in question as the initial leadership needs replacement, and credit, the heart of the experiment, lacks sufficient collateral. PMID:17942687

  8. Seismic images of the Brooks Range fold and thrust belt, Arctic Alaska, from an integrated seismic reflection/refraction experiment

    USGS Publications Warehouse

    Levander, A.; Fuis, G.S.; Wissinger, E.S.; Lutter, W.J.; Oldow, J.S.; Moore, T.E.

    1994-01-01

    We describe results of an integrated seismic reflection/refraction experiment across the Brooks Range and flanking geologic provinces in Arctic Alaska. The seismic acquisition was unusual in that reflection and refraction data were collected simultaneously with a 700 channel seismograph system deployed numerous times along a 315 km profile. Shot records show continuous Moho reflections from 0-180 km offset, as well as numerous upper- and mid-crustal wide-angle events. Single and low-fold near-vertical incidence common midpoint (CMP) reflection images show complex upper- and middle-crustal structure across the range from the unmetamorphosed Endicott Mountains allochthon (EMA) in the north, to the metamorphic belts in the south. Lower-crustal and Moho reflections are visible across the entire reflection profile. Travel-time inversion of PmP arrivals shows that the Moho, at 33 km depth beneath the North Slope foothills, deepens abruptly beneath the EMA to a maximum of 46 km, and then shallows southward to 35 km at the southern edge of the range. Two zones of upper- and middle-crustal reflections underlie the northern Brooks Range above ~ 12-15 km depth. The upper zone, interpreted as the base of the EMA, lies at a maximum depth of 6 km and extends over 50 km from the range front to the north central Brooks Range where the base of the EMA outcrops above the metasedimentary rocks exposed in the Doonerak window. We interpret the base of the lower zone, at ~ 12 km depth, to be from carbonate rocks above the master detachment upon which the Brooks Range formed. The seismic data suggest that the master detachment is connected to the faults in the EMA by several ramps. In the highly metamorphosed terranes south of the Doonerak window, the CMP section shows numerous south-dipping events which we interpret as a crustal scale duplex involving the Doonerak window rocks. The basal detachment reflections can be traced approximately 100 km, and dip southward from about 10-12 km

  9. African-American menthol and nonmenthol smokers: differences in smoking and cessation experiences.

    PubMed Central

    Okuyemi, Kolawole S.; Ebersole-Robinson, Maiko; Nazir, Niaman; Ahluwalia, Jasjit S.

    2004-01-01

    BACKGROUND: Despite smoking fewer cigarettes per day, African Americans have lower cessation rates and experience disproportionately higher rates of smoking-related health consequences. Because of their high preference for menthol cigarettes, it has been suggested that smoking menthol cigarettes may contribute to the excess smoking-related morbidity experienced by African Americans. Smoking menthol cigarettes could increase health risks from smoking if smokers of menthol cigarettes have lower cessation rates and thereby have longer duration of smoking compared to smokers of nonmentholated cigarettes. Few studies have examined associations between smoking of mentholated cigarettes and smoking cessation among African Americans. This study examined the smoking patterns of menthol cigarette smokers and their smoking cessation experiences. METHODS: A cross-sectional survey of 480 African-American smokers at an inner-city health center. Survey examined sociodemographics, smoking characteristics, and smoking cessation experiences of participants. Menthol smokers (n = 407) were compared to nonmenthol smokers (n = 73) in these characteristics. RESULTS: Menthol smokers were younger and more likely to smoke cigarettes with longer rod length, with filters, and those high in nicotine and tar. Although both groups did not differ by number of past quit attempts, time since most recent quit attempt was shorter for menthol smokers. The durations of most recent and longest-ever quit attempts were nonsignificantly shorter for menthol, compared to nonmenthol smokers. CONCLUSIONS: These data suggest that African-American menthol smokers are less successful with smoking cessation. Prospective studies are needed to confirm these findings and examine mechanisms underlying such differences. PMID:15481749

  10. Deep seismic refraction experiment in northeast Brazil: New constraints for Borborema province evolution

    NASA Astrophysics Data System (ADS)

    Lima, Marcus Vinicius A. G. de; Berrocal, Jesus; Soares, José E. P.; Fuck, Reinhardt A.

    2015-03-01

    The Borborema Province of northeastern Brazil is a major Proterozoic crustal province that, until now, has never been explored using deep crustal seismic methods. Here are reported the first results obtained from a high-quality seismic refraction/wide-angle reflection profile that has defined the internal seismic velocity structure and thickness of the crust in this region. Almost 400 recording stations were deployed in the Deep Seismic Refraction (DSR) experiment through an NW-SE ca. 900 km linear array and 19 shots were exploded at every 50 km along the line. Data from the 10 southeastern most shots of the seismic profile were processed in this work. The main features and geological structures crossed by the studied portion of the profile belong to the so-called Central Sub-province of the Borborema tectonic province. The crustal model obtained is compatible with a typical structure of extended crust. The model was essentially divided into three layers: upper crust, lower crust, and a half-space represented by the shallower portion of the mantle. The Moho is an irregular interface with depth ranging between 31.7 and 34.5 km, and beneath the Central Sub-province it varies from 31.5 to 33 km depth, where its limits are related to major crustal discontinuities. The distribution of velocities within the crust is heterogeneous, varying vertically from 5.7 to 6.3 km/s in the upper crust and from 6.45 to 6.9 km/s in the lower crust. From the average crustal velocity distribution it is evident that the Central Sub-province has seismic characteristics different from neighboring domains. The crust is relatively thin and crustal thickness variations in the profile are subtle due to stretching that occurred in the Cretaceous, during the fragmentation of Pangaea, opening of the South Atlantic Ocean and separation of South America from Africa.

  11. Exploring Crustal Structure and Mantle Seismic Anisotropy Associated with the Incipient Southern and Southwestern Branches of the East African Rift System

    NASA Astrophysics Data System (ADS)

    Yu, Y.; Reed, C. A.; Gao, S. S.; Liu, K. H.; Massinque, B.; Mdala, H. S.; Chindandali, P. R. N.; Moidaki, M.; Mutamina, D. M.

    2014-12-01

    In spite of numerous geoscientific studies, the mechanisms responsible for the initiation and development of continental rifts are still poorly understood. The key information required to constrain various geodynamic models on rift initiation can be derived from the crust/mantle structure and anisotropy beneath incipient rifts such as the Southern and Southwestern branches of the East African Rift System. As part of a National Science Foundation funded interdisciplinary project, 50 PASSCAL broadband seismic stations were deployed across the Malawi, Luangwa, and Okavango rift zones from the summer of 2012 to the summer of 2014. Preliminary results from these 50 SAFARI (Seismic Arrays for African Rift Initiation) and adjacent stations are presented utilizing shear-wave splitting (SWS) and P-S receiver function techniques. 1109 pairs of high-quality SWS measurements, consisting of fast polarization orientations and splitting times, have been obtained from a total of 361 seismic events. The results demonstrate dominantly NE-SW fast orientations throughout Botswana as well as along the northwestern flank of the Luangwa rift valley. Meanwhile, fast orientations beneath the eastern Luangwa rift flank rotate from NNW to NNE along the western border of the Malawi rift. Stations located alongside the western Malawi rift border faults yield ENE fast orientations, with stations situated in Mozambique exhibiting more E-W orientations. In the northern extent of the study region, fast orientations parallel the trend of the Rukwa and Usangu rift basins. Receiver function results reveal that, relative to the adjacent Pan-African mobile belts, the Luangwa rift zone has a thin (30 to 35 km) crust. The crustal thickness within the Okavango rift basin is highly variable. Preliminary findings indicate a northeastward thinning along the southeast Okavango border fault system congruent with decreasing extension toward the southwest. The Vp/Vs measurements in the Okavango basin are roughly

  12. Teacher and Parent Perceptions of Classroom Experiences of African American Male Students in a High School Alternative Program

    ERIC Educational Resources Information Center

    Johnson, Kimberly C.

    2013-01-01

    A major concern in the public schools is the low academic achievement of African American males. This mixed methods study examined the classroom experiences of African American male students in an alternative program. The dual purpose was to investigate the teachers' perceptions and their ability to provide best learning environments for…

  13. Community among African American Students on Small, Predominantly White Campuses: The Unforeseen "Minority within a Minority" Experience

    ERIC Educational Resources Information Center

    Journal of American College Health, 2005

    2005-01-01

    Sixteen African American students participated in semi-structured, open-ended interviews about their experiences at small, predominantly white colleges in the Appalachian region. Two main themes emerged from the interviews: community among minorities and minority within a minority. The students described community among African Americans on campus…

  14. "A Fly in the Ointment": African American Male Preservice Teachers' Experiences with Stereotype Threat in Teacher Education

    ERIC Educational Resources Information Center

    Scott, Sonya V.; Rodriguez, Louie F.

    2015-01-01

    This study draws from a larger phenomenological study on African American academic persistence and career aspirations in education. This article highlights three African American males' experiences with concentrated forms of stereotype threat in teacher education. Their voices revealed dimensions of how power and privilege operate in teacher…

  15. Not Merely a Matter of Academics: Student Experiences of a South African University as Study-Abroad Destination

    ERIC Educational Resources Information Center

    Paola, R. J.; Lemmer, E. M.

    2013-01-01

    Study abroad programmes attract considerable numbers of American college students; however, very few select an African country as their study-abroad destination. This article explores the experiences of American undergraduates who made the uncommon choice of a South African university as destination for a mid-length immersion type programme. The…

  16. How Religious Engagement Shapes the College Experience of African American Christian Males at a Predominantly White Institution: A Phenomenological Approach

    ERIC Educational Resources Information Center

    Rice, Stephen J.

    2012-01-01

    Understanding the different aspects of the college experience of African American males in a predominantly White institution is an important topic for researchers. This focus directly responds to the despairing statistics surrounding collegiate African American males, who often show lower graduation rates compared to other racial groups. The need…

  17. Race-ing through the School Day: African American Educators' Experiences with Race and Racism in Schools

    ERIC Educational Resources Information Center

    Jay, Michelle

    2009-01-01

    This article examines the ways African American educators experience themselves as raced individuals in their school settings and explores their perceptions of racial discrimination, subordination, and isolation. For this study, five African American educators participated in in-depth phenomenological interviews. Qualitative data analysis of their…

  18. Familial Factors in the Early Life Experiences of a Population of African American Crack-Cocaine Users: The Father Link?

    ERIC Educational Resources Information Center

    Dixon, Patricia

    1998-01-01

    Explored factors contributing to addiction in 140 African-American males in an inner-city homeless shelter. A common theme in their life stories is that of negative and painful experiences with father figures. Suggestions are made for research into this area and policy strategies to enhance the African-American father's role. (SLD)

  19. Diversifying the Secondary School Curriculum: The African Experience.

    ERIC Educational Resources Information Center

    Sifuna, Daniel N.

    1992-01-01

    Discusses the experiences of Tanzania, Botswana, Kenya, Sierra Leone, Zambia, and Zimbabwe in incorporating vocational education in secondary curricula by diversifying the whole formal educational system, creating parallel vocational systems, or injecting vocational components into the core curriculum. Discusses reasons that outcomes did not meet…

  20. Advancing Explosion Source Theory through Experimentation: Results from Seismic Experiments Since the Moratorium on Nuclear Testing

    NASA Astrophysics Data System (ADS)

    Bonner, J. L.; Stump, B. W.

    2011-12-01

    On 23 September 1992, the United States conducted the nuclear explosion DIVIDER at the Nevada Test Site (NTS). It would become the last US nuclear test when a moratorium ended testing the following month. Many of the theoretical explosion seismic models used today were developed from observations of hundreds of nuclear tests at NTS and around the world. Since the moratorium, researchers have turned to chemical explosions as a possible surrogate for continued nuclear explosion research. This talk reviews experiments since the moratorium that have used chemical explosions to advance explosion source models. The 1993 Non-Proliferation Experiment examined single-point, fully contained chemical-nuclear equivalence by detonating over a kiloton of chemical explosive at NTS in close proximity to previous nuclear explosion tests. When compared with data from these nearby nuclear explosions, the regional and near-source seismic data were found to be essentially identical after accounting for different yield scaling factors for chemical and nuclear explosions. The relationship between contained chemical explosions and large production mining shots was studied at the Black Thunder coal mine in Wyoming in 1995. The research led to an improved source model for delay-fired mining explosions and a better understanding of mining explosion detection by the International Monitoring System (IMS). The effect of depth was examined in a 1997 Kazakhstan Depth of Burial experiment. Researchers used local and regional seismic observations to conclude that the dominant mechanism for enhanced regional shear waves was local Rg scattering. Travel-time calibration for the IMS was the focus of the 1999 Dead Sea Experiment where a 10-ton shot was recorded as far away as 5000 km. The Arizona Source Phenomenology Experiments provided a comparison of fully- and partially-contained chemical shots with mining explosions, thus quantifying the reduction in seismic amplitudes associated with partial

  1. Large heterogeneous structure beneath the Atotsugawa Fault, central Japan, revealed by seismic refraction and reflection experiments

    NASA Astrophysics Data System (ADS)

    Iidaka, Takashi; Kurashimo, Eiji; Iwasaki, Takaya; Arai, Ryuta; Kato, Aitaro; Katao, Hiroshi; Yamazaki, Fumihito

    2015-08-01

    A high-strain-rate zone termed the Niigata Kobe Tectonic Zone is located in central Japan and contains an active right-lateral fault called the Atotsugawa Fault. We present the results of an explosive-source seismic experiment that focused on identifying the formation mechanisms of the fault. The experiment used seven explosive sources and 1108 seismic stations, and was undertaken during October 2007 in the area of the Atotsugawa Fault. The seismic stations were set up on a survey line with a length of ~ 170 km, oriented orthogonal to the strike of the fault. The linear array was used to identify the seismic structure of the fault zone and the deeper parts of the crust in the study area, yielding fine details of the seismic structure of the crust along the profile line, including lateral variations in P-wave velocity and the configuration of layers in the crust. A relatively low P-wave velocity reflective zone was detected beneath the fault at depths of 15-25 km. This zone also has extremely low S-wave velocities, directly underlies three active faults, and contains three low-resistivity zones that underlie these faults. These reflective and low-resistivity zones are thought to represent fluid within the crust, and the data obtained during this study are consistent with a weak zone model for the formation of the active faults in the study area. This suggests that the reflective layer represents a weak zone in the lower crust that is responsible for the concentration of deformation within the upper crust. The presence of abundant fluids beneath the Atotsugawa Fault could also reduce the strength of the lower crust, again focusing deformation related to the regional stress regime in areas that overlie these fluid-containing zones. The results suggest that the reflective layer was an important factor in the formation of the Atotsugawa Fault.

  2. Deep Seismic Reflection Profiling in Africa

    NASA Astrophysics Data System (ADS)

    Attoh, K.; Brown, L. D.

    2006-05-01

    Africa represents one of the true frontiers for systematic deep seismic reflection profiling of the type pioneered by COCORP, LITHOPROBE, BIRPS, DEKORP, and ECORS in the northern hemisphere. However, there have been a number of notable individual surveys that have sampled key components of the African lithosphere, and several systematic regional geophysical initiatives which suggest African is fertile ground for future efforts. Among the latter are the KRISP refraction/wide-angle program to probe the East African Rift system in the 1990's, the Kaapvaal Experiment to image the deep lithosphere with passive techniques and most recently the EAGLE active/passive experiments in the Afar. Examples of true multichannel deep reflection surveys to delineate crustal structure include the transects of the Limpopo Belt, a Neoarchean mobile zone that sutures the Kaapval and Zimbabwe cratons, deep oil prospecting surveys in the Nosop basin of southern Botswana that reveal dramatic basement reflectors off the NW margin of the Kaapvaal craton, and most recently deep vibroseis surveys within the Kaapvaal craton that indicate a crustal stack of tectonic slivers as well as tectonic shingling of the upper mantle. The passive margin of western Africa, with its strategic oil resources, has been a target of several deep studies using marine seismic surveys, including the PROBE initiative of the late 1980's and more recent deep surveys offshore Angola. Reprocessing of lines from oil exploration grids reveal Proterozoic mid-lower crustal features offshore of Ghana. Among the potentially rich targets for future surveys in Africa are the West African and Congo cratons and their suturing Pan-African (Neoproterozoic) mobile belts. This suite of cratonic lithosphere elements is largely largely untouched by modern high resolution seismic methodologies. New initiatives such as LEGENDS ( targeting the East African Orogen) and exploitation of existing oil industry seismic data for deep information

  3. The structure and subsidence of Rockall Trough from two-ship seismic experiments

    SciTech Connect

    Joppen, M.; White, R.S. )

    1990-11-10

    Coincident multichannel seismic reflection and refraction profiles acquired northwest of Britain during a two-ship seismic experiment in the southern Rockall Trough provide evidence for a thin (6 km) syn-rift crust below Rockall Trough. The variation of seismic velocity with depth is consistent with either oceanic crust similar to that found in other parts of the North Atlantic or with thinned continental crust heavily intruded by syn-rift igneous rocks. The syn-rift crust beneath Rockall Trough is now buried by nearly 5 km of sediments that are intruded by Tertiary volcanics varying in extent from isolated sills to a large sill complex extending 100 km laterally. The basement imaged on seismic profiles exhibits a band of subhorizontal reflectors that extend laterally over distances of up to 40 km which they interpret as sediments intercalated with submarine lava flow generated during the opening of the Trough. Estimates of stretching from crustal thinning and from subsidence indicate that Rockall Trough has undergone extensive rifting ({beta} > 6). Upwelling asthenosphere beneath the thinned lithosphere generated at least 1-3 km thickness of melt as it decompressed. The molten rock rose upward from the mantle until it was in part extruded as lava flows and in part intruded into the crust.

  4. An Intersectional Social Capital Analysis of the Influence of Historically Black Sororities on African American Women's College Experiences at a Predominantly White Institution

    ERIC Educational Resources Information Center

    Greyerbiehl, Lindsay; Mitchell, Donald, Jr.

    2014-01-01

    Research exploring the college experiences of African American women at predominantly White institutions (PWI) continues to be a necessity as African American women graduate at lower rates than their racial/ethnic peers. This qualitative study explored the influence historically Black sororities had on the college experiences of African American…

  5. The influences and experiences of African American undergraduate science majors at predominately White universities

    NASA Astrophysics Data System (ADS)

    Blockus, Linda Helen

    The purpose of this study is to describe and explore some of the social and academic experiences of successful African American undergraduate science majors at predominately White universities with the expectation of conceptualizing emerging patterns for future study. The study surveyed 80 upperclass African Americans at 11 public research universities about their perceptions of the influences that affect their educational experiences and career interests in science. The mailed survey included the Persistence/ voluntary Dropout Decision Scale, the Cultural Congruity Scale and the University Environment Scale. A variety of potential influences were considered including family background, career goals, psychosocial development, academic and social connections with the university, faculty relationships, environmental fit, retention factors, validation, participation in mentored research projects and other experiences. The students' sources of influences, opportunities for connection, and cultural values were considered in the context of a research university environment and investigated for emerging themes and direction for future research. Results indicate that performance in coursework appears to be the most salient factor in African American students' experience as science majors. The mean college gpa was 3.01 for students in this study. Challenging content, time demands, study habits and concern with poor grades all serve to discourage students; however, for most of the students in this study, it has not dissuaded them from their educational and career plans. Positive course performance provided encouragement. Science faculty provide less influence than family members, and more students find faculty members discouraging than supportive. Measures of faculty relations were not associated with academic success. No evidence was provided to confirm the disadvantages of being female in a scientific discipline. Students were concerned with lack of minority role models

  6. Striving to be in the profession and of It: the African American experience in physical education and kinesiology.

    PubMed

    Wiggins, David K; Wiggins, Brenda P

    2011-06-01

    This study analyzes the experiences of African Americans in the physical education and kinesiology profession since the late 1850s. Using a variety of primary and secondary source material, we place special emphasis on the experiences of African American physical educators in higher education and in the American Alliance for Health, Physical Education, Recreation and Dance and its southern, regional, and state chapters. Apparent from this examination is that African Americans have experienced various forms of racially discriminatory practices in physical education and kinesiology and have found it extraordinarily difficult to assume leader ship positions in the profession and be acknowledged for their scholarly and academic accomplishments. PMID:21699112

  7. Deep-imaging seismic and gravity results from the offshore Cameroon Volcanic Line, and speculation of African hotlines

    NASA Astrophysics Data System (ADS)

    Meyers, Jayson B.; Rosendahl, Bruce R.; Harrison, Christopher G. A.; Ding, Zan-Dong

    1998-01-01

    Deep-imaging multi-channel seismic reflection data show that volcanic centers along the offshore part of the Cameroon Volcanic Line (CVL) are composed of uplifted, Aptian to Late Cretaceous oceanic crust, >4 km of sedimentary overburden, and Neogene igneous rocks, with volcanic material forming a cap < 1.5 km thick over pre-uplift sedimentary deposits. At Príncipe Island, the underlying oceanic basement has been uplifted by as much as 3 km to form a crustal arch less than 200 km wide perpendicular to the CVL trend. Vertical faults having small offsets and dikes are common across this arch. Reflection Moho shallows parallel to the uplifted crust along margins of the arch, but is not observed directly below the arch axis where volcanism and faulting are pervasive. The episode of crustal uplift is marked by a prominent reflection unconformity. This unconformity occurs at other CVL islands and seamounts and represents a synchronous period of crustal uplift and volcanism. Reflectors from this unconformity have been correlated to offshore boreholes indicating a Miocene age. Gravity modelling indicates that an elongate wedge of relatively less dense lithospheric mantle (Δρ = -0.1 g/cm 3) underlies Príncipe Island to a depth of 40 km. This interpreted zone of lighter mantle material may form by a combination of intruded mafic partial melt and reheating of the lithosphere. Dynamic support from asthenospheric upwelling may also have contributed to uplift. Other NE-trending volcanic chains and rises off West Africa (Canary Islands, Cape Verde Rise, Sierra Leone Rise and Walvis Ridge) display similar features to CVL islands. These volcanic chains exhibit crustal uplift unconformities and intraplate volcanism occurring during the Miocene and later; Miocene and older marine sediments crop out on most of the islands; there are no flexural depressions surrounding volcanic centers; their ocean island basalts (OIB) have similar geochemical characteristics; the OIB does not

  8. African American eighth-grade female students' perceptions and experiences as learners of science literacy

    NASA Astrophysics Data System (ADS)

    Crim, Sharan R.

    The National Assessment of Educational Progress (2000) reports an achievement gap between male and female students and majority and minority students in science literacy. Rutherford and Algren (2000) describe a scientifically literate person as one who is aware that science, mathematics, and technology are interdependent human enterprises with strengths and limitations; understands key concepts and principles of science; is familiar with the natural world and recognizes both its diversity and unity; and uses scientific knowledge and scientific ways of thinking for individual and social purposes. The purpose of this qualitative case study research was to investigate African American eighth grade female students' perceptions and experiences as learners of science literacy. A social learning theory (Bandura, 1986) and constructivist theory (Vygotsky, 1977) served as a guide for the researcher. Two questions were explored: (1) What are African American eighth grade female students' perceptions and experiences as learners of science literacy? (2) In what ways do the perceptions and experiences of African American eighth grade female students influence their learning of science literacy? Purposeful sampling (Merriam, 1998) was used with four African American eighth grade female students selected as participants for the study. Data collection and analysis occurred between February and August in a single year. Data sources included an open-ended questionnaire, two in-depth interviews with each participant (Seidman, 1991); classroom observations, participant reflective journals, student artifacts, and a researcher's log. Data were analyzed through the constant comparative method (Glaser & Strauss, 1967), and richly descriptive participant portraits and qualitative case studies (Merriam, 1998) were used to report the findings. Three themes emerged from the study that positively affected the perceptions and experiences of African American eighth grade female students as

  9. Expecting the Unexpected: a Comparative Study of African-American Women's Experiences in Science during the High School Years

    NASA Astrophysics Data System (ADS)

    Hanson, Sandra L.; Johnson, Elizabeth Palmer

    Data from the National Educational Longitudinal Study (NELS) for the years 1988 to 1992 are used to explore the science experiences of young African-American women during the high school years. The comparison groups we use in trying to understand these experiences involve White women (for a race contrast) and African-American men (for a gender contrast). Within the context of a critical feminist perspective, it is argued that gender is constructed in a different way in White and African-American communities. Instead of expecting a disadvantage for young African-American women because of their gender and minority statuses, it is suggested that unique gender ideologies and work-family arrangements in the African-American community give these young women the resources and agency that allow them to compete with their White female counterparts and their African-American male counterparts in the science domain. Results from our analyses of the NELS data confirm these expectations. We find that on a majority of science measures, African-American women do as well as - and sometimes better than - White women and African-American men. For example, there are no differences between African-American women and men on attitudes toward science. And when compared with White women, African-American women tend to have more positive attitudes. When disadvantages appear for these young African-American women, they are more likely to be race effects then gender effects. The minimal gender effects in the science experiences of young African-Americans is in contrast to the more frequent male advantage in the White sample. A careful examination of family and individual resources shows that African-American families compensate for disadvantages on some resources (e.g., family socioeconomic status) by providing young women with an excess of other resources (e.g., unique gender ideologies, work expectations, and maternal expectations and involvement). And, unlike White parents, they sometimes

  10. From their own voices: the lived experience of African American registered nurses.

    PubMed

    Wilson, Deborah W

    2007-04-01

    This phenomenological study described the lived experience of African American registered nurses providing nursing care to individuals, families, and communities in southeast Louisiana. Data were collected from 13 African American registered nurses using semistructured interviews and a focus group. Analysis of the phenomenological data revealed two essential themes, (a) connecting with the patient and (b) proving yourself; and four incidental themes, (a) a fulfilling dream, (b) being invisible and voiceless, (c) surviving and persevering, and (d) mentoring and role modeling. The findings revealed that the general perception among participants was that they were not fully accepted as equal professionals by their Caucasian nurse colleagues, other health care providers, and sometimes patients. The findings of the study indicate the immediate need to address and resolve the issues of diversity within the nursing profession. Nursing will also have to reform its system and practices to embrace and support diversity. PMID:17416716

  11. Seismic risk mitigation in deep level South African mines by state of the art underground monitoring - Joint South African and Japanese study

    NASA Astrophysics Data System (ADS)

    Milev, A.; Durrheim, R.; Nakatani, M.; Yabe, Y.; Ogasawara, H.; Naoi, M.

    2012-04-01

    Two underground sites in a deep level gold mine in South Africa were instrumented by the Council for Scientific and Industrial Research (CSIR) with tilt meters and seismic monitors. One of the sites was also instrumented by JApanese-German Underground Acoustic emission Research in South Africa (JAGUARS) with a small network, approximately 40m span, of eight Acoustic Emission (AE) sensors. The rate of tilt, defined as quasi-static deformations, and the seismic ground motion, defined as dynamic deformations, were analysed in order to understand the rock mass behavior around deep level mining. In addition the high frequency AE events recorded at hypocentral distances of about 50m located at 3300m below the surface were analysed. A good correspondence between the dynamic and quasi-static deformations was found. The rate of coseismic and aseismic tilt, as well as seismicity recorded by the mine seismic network, are approximately constant until the daily blasting time, which takes place from about 19:30 until shortly before 21:00. During the blasting time and the subsequent seismic events the coseismic and aseismic tilt shows a rapid increase.Much of the quasi-static deformation, however, occurs independently of the seismic events and was described as 'slow' or aseismic events. During the monitoring period a seismic event with MW 2.2 occurred in the vicinity of the instrumented site. This event was recorded by both the CSIR integrated monitoring system and JAGUARS acoustic emotion network. The tilt changes associated with this event showed a well pronounced after-tilt. The aftershock activities were also well recorded by the acoustic emission and the mine seismic networks. More than 21,000 AE aftershocks were located in the first 150 hours after the main event. Using the distribution of the AE events the position of the fault in the source area was successfully delineated. The distribution of the AE events following the main shock was related to after tilt in order to

  12. Martian seismicity

    NASA Technical Reports Server (NTRS)

    Phillips, Roger J.; Grimm, Robert E.

    1991-01-01

    The design and ultimate success of network seismology experiments on Mars depends on the present level of Martian seismicity. Volcanic and tectonic landforms observed from imaging experiments show that Mars must have been a seismically active planet in the past and there is no reason to discount the notion that Mars is seismically active today but at a lower level of activity. Models are explored for present day Mars seismicity. Depending on the sensitivity and geometry of a seismic network and the attenuation and scattering properties of the interior, it appears that a reasonable number of Martian seismic events would be detected over the period of a decade. The thermoelastic cooling mechanism as estimated is surely a lower bound, and a more refined estimate would take into account specifically the regional cooling of Tharsis and lead to a higher frequency of seismic events.

  13. Seismic mapping of shallow fault zones in the San Gabriel Mountains from the Los Angeles Region Seismic Experiment, southern California

    USGS Publications Warehouse

    Fuis, G.S.; Ryberg, T.; Lutter, W.J.; Ehlig, P.L.

    2001-01-01

    During the Los Angeles Region Seismic Experiment (LARSE), a reflection/refraction survey was conducted along a profile (line 1) extending from Seal Beach, California, northeastward to the Mojave Desert and crossing the Los Angeles and San Gabriel Valley basins and San Gabriel Mountains. In most shot gathers from the southern and central San Gabriel Mountains, clear secondary arrivals are seen that merge, or appear to merge, with first arrivals at three locations, including the location of the Vincent thrust fault, an exposed late Mesozoic/early Cenozoic megathrust. These secondary arrivals are interpretable as reflections in the shallow crust (<5 km depth) from a concave-upward interface that projects to the surface in the north near the Vincent thrust fault, is offset in its central part at the San Gabriel fault (an old branch of the San Andreas fault), and terminates in the south at 1 to 2 km depth at the southern mountain front. The velocity structure above and below this interface strongly suggests it is the Vincent thrust fault: intermediate velocities (6.2 km/s), consistent with mylonites overlying the Vincent thrust fault, are observed above it; lower velocities (5.8 km/s), consistent with the Pelona Schist underlying the Vincent thrust fault, are observed below it. Problems arise, however, in attempting to match this reflector to the exposed Vincent thrust fault, which is seen in outcrops east of line 1. The Vincent thrust fault is shallower than the reflector in most places. An unmapped structure (steep fault, monocline, or thrust fault) is required between line 1 and the outcrops that either drops the Vincent thrust fault down to the depths of the reflector or repeats the Vincent thrust fault beneath line 1 in the footwall of another thrust fault. An alternative interpretation of the reflector is a deep greenstone horizon within the Pelona Schist, although this alternative is not favored by the velocity structure. Copyright 2001 by the American

  14. Data report for the 1985 seismic-refraction experiment at Yucca Mountain and vicinity, southwestern Nevada

    SciTech Connect

    Sutton, V.D.

    1985-12-31

    In February 1985, the US Geological Survey (USGS) conducted a seismic-refraction survey in the vicinity of Yucca Mountain, southwestern Nevada to better define the P(compressional)-wave velocity structure of the upper crust in this area. This experiment is a continuation of seismic investigations at the Nevada Test Site (NTS) by the USGS on behalf of the Nevada Nuclear Waste Storage Investigations Project (NNWSI) to assess the feasibility of a proposed nuclear waste disposal site at Yucca Mountain. The 1985 seismic-refraction survey consisted of three separate deployments: two East-West profiles, Line A and Line B, and a North-South profile (Plate 1). Thirty-one shots were recorded by 120 portable seismographs, where recorder station spacing averaged .3 km, and the shotpoints averaged 5 to 8 km apart. Additionally, off set shots were fired at shotpoints located about 7 to 15 km from the endpoints of the deployment lines. This report includes record sections from the twenty-nine shotpoints (Plates 2 to 17), a list of seismograph locations (Appendix A), a list of shotpoint locations and shot times, DKDAT data files and Tape Grade Code (Appendix B), and a list of first-arrival traveltime picks (Appendix C). Detailed interpretation of these data will be published in a subsequent report.

  15. What makes African American health disparities newsworthy? An experiment among journalists about story framing

    PubMed Central

    Hinnant, Amanda; Oh, Hyun Jee; Caburnay, Charlene A.; Kreuter, Matthew W.

    2011-01-01

    News stories reporting race-specific health information commonly emphasize disparities between racial groups. But recent research suggests this focus on disparities has unintended effects on African American audiences, generating negative emotions and less interest in preventive behaviors (Nicholson RA, Kreuter MW, Lapka C et al. Unintended effects of emphasizing disparities in cancer communication to African-Americans. Cancer Epidemiol Biomarkers Prev 2008; 17: 2946–52). They found that black adults are more interested in cancer screening after reading about the progress African Americans have made in fighting cancer than after reading stories emphasizing disparities between blacks and whites. This study builds on past findings by (i) examining how health journalists judge the newsworthiness of stories that report race-specific health information by emphasizing disparities versus progress and (ii) determining whether these judgments can be changed by informing journalists of audience reactions to disparity versus progress framing. In a double-blind-randomized experiment, 175 health journalists read either a disparity- or progress-framed story on colon cancer, preceded by either an inoculation about audience effects of such framing or an unrelated (i.e. control) information stimuli. Journalists rated the disparity-frame story more favorably than the progress-frame story in every category of news values. However, the inoculation significantly increased positive reactions to the progress-frame story. Informing journalists of audience reactions to race-specific health information could influence how health news stories are framed. PMID:21911844

  16. Early life experiences linked to diabetes mellitus: a study of African-American migration.

    PubMed Central

    Schneider, D.; Greenberg, M.; Lu, L.

    1997-01-01

    African Americans experienced massive internal migrations that shifted more than 6 million Southern-born blacks to other sections of the United States over the past century, a trend that only recently has been reversed. Whenever mass migration takes place, there is an opportunity to examine the role of the native and relocated environments in the development of disease. This article examines those relationships for diabetes mellitus, a group of diseases that disproportionately affect African-Americans relative to other racial and ethnic groups in the United States. Age-specific and age-adjusted rates with 95% confidence intervals were calculated for males and females for combinations of five regions of birth and four regions of residence at time of death. Southern-born males had statistically significantly higher death rates from diabetes than did their counterparts who died in the same regions in 9 of 16 comparisons. For females, those born in the South had statistically significantly higher rates in 15 of 16 comparisons. The results of this study indicate that place of birth and early life experiences are statistically associated with diabetes mortality among African Americans regardless of place of residence at time of death. PMID:9002414

  17. TOMO-ETNA MED-SUV.ISES an active seismic and passive seismic experiment at Mt. Etna volcano. An integrated marine and onland geophysical survey.

    NASA Astrophysics Data System (ADS)

    Ibáñez, Jesus. M.; Patane, Domenico; Puglisi, Guisseppe; Zuccarello, Lucciano; Bianco, Francesca; Luehr, Birger; Diaz-Moreno, Alejandro; Prudencio, Janire; Koulakov, Ivan; Del Pezzo, Edoardo; Cocina, Ornella; Coltelli, Mauro; Scarfi, Lucciano; De Gori, Pascuale; Carrion, Francisco

    2014-05-01

    An active seismic experiment to study the internal structure of Etna Volcano is going to carried out on Sicily and Aeolian islands. The main objective of the TOMO-ETNA MED-SUV.ISES experiment, beginning in summer 2014, is to perform a high resolution seismic tomography, in velocity and attenuation, in Southern Italy, by using active and passive seismic data, in an area encompassing outstanding volcanoes as Mt. Etna, and Aeolian volcanoes. The achievement of this objective is based on the integration and sharing of the in-situ marine and land experiments and observations and on the implementation of new instruments and monitoring systems. For the purpose, onshore and offshore seismic stations and passive and active seismic data generated both in marine and terrestrial environment will be used. Additionally, other geophysical data, mainly magnetic and gravimetric data will be considered to obtain a joint Upper Mantle-Crust structure that could permit to make progress in the understanding of the dynamic of the region. This multinational experiment which involves institutions from Spain, Italy, Germany, United Kingdom, Ireland, France, Malta, Portugal, Russia, USA and Mexico. During the experiment more than 6.600 air gun shots performed by the Spanish Oceanographic vessel "Sarmiento de Gamboa" will be recorder on a dense local seismic network consisting of 100 on land non-permanent stations, 70 on land permanent stations and 20-25 OBSs. Contemporaneously other marine geophysical measures will be performed using a marine Gravimeter LaCoste&Romberg Air-Sea Gravity System II and a Marine Magnetometer SeaSPY. The experiments will provide a unique data set in terms of data quantity and quality, and it will provide a detailed velocity and attenuation structural image of volcano edifice. The results will be essential in the development and interpretation of future volcanic models. It is noteworthy that this project is fully transversal, multidisciplinary and crosses several

  18. Initial Results from the 2002 Gulf of California Conjugate Margin Seismic Experiment

    NASA Astrophysics Data System (ADS)

    Holbrook, S.; Lizarralde, D.; Kent, G.; Harding, A.; Fletcher, J.; Gonzalez-Fernandez, A.; Umhoefer, P.; Axen, G.

    2003-04-01

    The Gulf of California, which marks the ongoing separation of Baja California from mainland Mexico, is one of the few locales where active continental breakup can be studied along unambiguous flow lines that join clear conjugate margin pairs. In Fall 2002, we conducted an onshore-offshore seismic experiment across the conjugate rifted margins of the Gulf of California in several rift segments. The joint U.S.-Mexico project, sponsored principally by the MARGINS program of the U.S. National Science Foundation, aimed to image crustal structure across conjugate margins of four major basins to determine the modes of extension and the influence of sedimentation and magmatism on breakup. Here we present an overview of the experiment, which was substantially altered at sea due to concerns for marine-mammal safety, and present some preliminary findings. Three flow-line transects were acquired, in the Alarcon Basin, the Guaymas Basin, and between Cabo and Tres Marias Islands. In addition, a fourth transect across the Baja Peninsula was acquired. Data acquired included (1) multichannel seismic reflection data using the R/V Ewing’s 20-gun array and 480-channel, 6-km-long streamer, (2) wide-angle reflection/refraction data recorded on ocean-bottom seismometers, from 206 deployments conducted by the R/V New Horizon, and (3) onshore-offshore data recorded on portable seismometers deployed up to 100 km inland on all transects. Initial results from the experiment include (1) clear evidence for asymmetric basement structure on the conjugate rifted margins and across the active mid-ocean spreading center, of the Guaymas Basin, (2) the suggestion of substantial magmatism in an early failed rift of the Alarcon Basin, and (3) active subduction beneath the margin at the Tres Marias islands. In addition, we will discuss new procedures for mitigating effects on marine mammals that may have a significant impact on future U.S.-sponsored seismic reflection activities.

  19. Crustal structure variations along the NW-African continental margin: A comparison of new and existing models from wide-angle and reflection seismic data

    NASA Astrophysics Data System (ADS)

    Klingelhoefer, Frauke; Biari, Youssef; Sahabi, Mohamed; Aslanian, Daniel; Schnabel, Michael; Matias, Luis; Benabdellouahed, Massinissa; Funck, Thomas; Gutscher, Marc-André; Reichert, Christian; Austin, James A.

    2016-04-01

    Deep seismic data represent a key to understand the geometry and mechanism of continental rifting. The passive continental margin of NW-Africa is one of the oldest on earth, formed during the Upper Triassic-Lower Liassic rifting of the central Atlantic Ocean over 200 Ma. We present new and existing wide-angle and reflection seismic data from four study regions along the margin located in the south offshore DAKHLA, on the central continental margin offshore Safi, in the northern Moroccan salt basin, and in the Gulf of Cadiz. The thickness of unthinned continental crust decreases from 36 km in the North to about 27 km in the South. Crustal thinning takes place over a region of 150 km in the north and only 70 km in the south. The North Moroccan Basin is underlain by highly thinned continental crust of only 6-8 km thickness. The ocean-continent transition zone shows a variable width between 40 and 70 km and is characterized by seismic velocities in between those of typical oceanic and thinned continental crust. The neighbouring oceanic crust is characterized by a thickness of 7-8 km along the complete margin. Relatively high velocities of up to 7.5 km/s have been imaged between magnetic anomalies S1 and M25, and are probably related to changes in the spreading velocities at the time of the Kimmeridgian/Tithonian plate reorganization. Volcanic activity seems to be mostly confined to the region next to the Canary Islands, and is thus not related to the initial opening of the ocean, which was associated to only weak volcanism. Comparison with the conjugate margin off Nova Scotia shows comparable continental crustal structures, but 2-3 km thinner oceanic crust on the American side than on the African margin.

  20. A Gravity data along LARSE (Los Angeles Regional Seismic Experiment) Line II, Southern California

    USGS Publications Warehouse

    Wooley, R.J.; Langenheim, V.E.

    2001-01-01

    The U.S. Geological Survey conducted a detailed gravity study along part of the Los Angeles Regional Seismic Experiment (LARSE) transect across the San Fernando Basin and Transverse Ranges to help characterize the structure underlying this area. 249 gravity measurements were collected along the transect and to augment regional coverage near the profile. An isostatic gravity low of 50-60 mGal reflects the San Fernando-East Ventura basin. Another prominent isostatic gravity with an amplitude of 30 mGal marks the Antelope Valley basin. Gravity highs occur over the Santa Monica Mountains and the Transverse Ranges. The highest isostatic gravity values coincide with outcrops of Pelona schist.

  1. Seismic and Geodynamic Constraints on Compositional Heterogeneity in the Lower Mantle: Implications for Deeply-Rooted Hot Upwellings Under the African and Pacific Plates

    NASA Astrophysics Data System (ADS)

    Forte, A. M.; Glisovic, P.; Rowley, D. B.; Simmons, N. A.; Grand, S. P.; Lu, C.

    2014-12-01

    We present the results of a series of tests that probe the possible existence of compositionally distinct material in the central core of the LLSVPs under the African and Pacific plates using tomography-based mantle flow models that employ several independently-derived viscosity profiles (Mitrovica & Forte 2004, Behn et al. 2004, Steinberger & Calderwood 2006, Forte et al. 2010). We also consider four global tomography models derived from seismic shear velocity data alone (Grand 2002, Panning & Romanowicz 2006, Kustowski et al. 2008, Ritsema et al. 2011). The possible combinations of viscosity and tomography models yield 16 different tests for compositional heterogeneity inside the LLSVPs. In all tests we begin with a mineral physical scaling between lower-mantle shear velocity and density anomalies that assumes thermal effects are dominant everywhere, including within the LLSVPs. We find it is not possible, in any of the tests, to obtain a satisfactory fit to surface geodynamic data, especially the global, long-wavelength gravity anomalies and space-geodetic inferences of excess CMB flattening with a purely thermal interpretation of lower-mantle heterogeneity. If we introduce compositionally-distinct material in the central portions of the LLSVPs, all tests show a notable improvement in the fit to the gravity anomaly and CMB ellipticity data. An optimal reconciliation of the gravity and CMB data is obtained by extending compositional heterogeneity upwards, with maximum-amplitude in the seismic D"-layer and tapering off to negligible values in the mid-mantle. A robust assessment of the dynamical impact of this deeply-rooted compositional heterogeneity is obtained with maps of "mean" convective flow, by averaging the results of all 16 test cases. We find (see map below) dominant lower-mantle upwellings below the axis of the East Pacific Rise (EPR), and under the Caroline Islands in the Western Pacific. Under the African plate we find large-scale upwellings under the

  2. The experience of African American women living with HIV: creating a prevention film for teens.

    PubMed

    Norris, Anne E; DeMarco, Rosanna

    2005-01-01

    The personal and social costs of HIV are well documented. What remains unknown is the effect of public disclosure of HIV status on the individual who is doing the disclosing. This study describes the experience of four African American women living with HIV who participated in the development of an intergenerational education intervention for African American adolescent girls. These women suggested that they be filmed discussing the "dark side" of HIV in an effort to create an intergenerational education intervention that would alter the risk-taking behavior that they observed in young women in their community. After a rough cut of the film was completed, these women viewed the film and participated in a focus group during which they discussed what it was like to reveal and revisit their own painful experiences associated with becoming infected and then living with HIV. Findings from content analysis of transcribed dialogue included the following positive themes: (a) self-acceptance by telling one's own story and hearing the stories of the other women, (b) a sense of liberation by disclosing publicly one's image and message and letting go of others' judgments, (c) feeling supported by meeting other women who share the same experience, (d) value of using the film to impact or save young people from the pain one has experienced. A negative theme emerged related to personal pain in reliving the individual's history with HIV. PMID:16438124

  3. Disability and Health: Exploring the Disablement Experience of Young Adult African Americans

    PubMed Central

    Harrison, Tracie

    2013-01-01

    Purpose The objective of this study was to examine disablement as experienced by young adult African American men and women with permanent mobility impairment. Methods This study included a sample of 5 male and 5 female participants ranging in age from 22 to 39. An exploratory descriptive design and qualitative methods, including interviews and fieldnotes, were used. Interview data was analyzed using the process of inductive qualitative content analysis. Results Basic desires for independence, shared intimacy, and psychological and physical health were not diminished by physical limitations. The disablement experience of this group is reflected in the themes of “Cumulative Losses” and “Sustained Desires.” The findings of this study describe the high level of motivation that young adult African American men and women with disabilities have to improve levels of health and well-being within the context of their impairments. Conclusion This study provides a better understanding of the contextual factors and experiences that may contribute to the development of further disability and subsequent health-related problems over time. Increased knowledge of the disablement experience of these young men and women may assist health care entities and social service providers in improving health care and rehabilitation efforts targeting this group. PMID:23745770

  4. Preliminary Results from the iMUSH Active Source Seismic Experiment

    NASA Astrophysics Data System (ADS)

    Levander, Alan; Kiser, Eric; Palomeras, Imma; Zelt, Colin; Schmandt, Brandon; Hansen, Steve; Harder, Steven; Creagar, Kenneth; Vidale, John; Abers, Geoffrey

    2015-04-01

    iMUSH (imaging Magma Under Saint Helens) is a US NSF sponsored multi-disciplinary investigation of Mount Saint Helens (MSH), currently the most active volcano in the Cascades arc in the northwestern United States. The project consists of active and passive seismic experiments, extensive magnetotelluric sounding, and geological/geochemical studies involving scientists at 7 institutions in the U.S. and Europe. The long-term goal of the seismic project is to combine analysis of the active source data with that of data from the 70 element broadband seismograph operating from summer 2014 until 2016. Combining seismic and MT analyses with other data, we hope to image the MSH volcanic plumbing system from the surface to the subducting Juan de Fuca slab. Here we describe preliminary results of the iMUSH active source seismic experiment, conducted in July and August 2014. The active source experiment consisted of twenty-three 454 or 908 kg weight shots recorded by ~3500 seismographs deployed at ~6,000 locations. Of these instruments, ~900 Nodal Seismic instruments were deployed continuously for two weeks in an areal array within 10 km of the MSH summit. 2,500 PASSCAL Texan instruments were deployed twice for five days in 3 areal arrays and 2 dense orthogonal linear arrays that extended from MSH to distances > 80 km. Overall the data quality from the shots is excellent. The seismograph arrays also recorded dozens of micro-earthquakes beneath the MSH summit and along the MSH seismic zone, and numerous other local and regional earthquakes. In addition, at least one low frequency event beneath MSH was recorded during the experiment. At this point we have begun various types of analysis of the data set: We have determined an average 1D Vp structure from stacking short-term/long-term average ratios, we have determined the 2-D Vp structure from ray-trace inversions along the two orthogonal profiles (in the NW-SE and NE-SW directions), and we have made low-fold CMP stacks of the

  5. Infected Lives: Lived Experiences of Young African American HIV-Positive Women.

    PubMed

    Peltzer, Jill N; Domian, Elaine W; Teel, Cynthia S

    2016-02-01

    This hermeneutic phenomenological study explored the lived experiences of young African American HIV-infected women. Eleven women between the ages of 21 and 35 participated. One pattern, Infected Lives, and three themes--Living Alone With HIV, Living With Unresolved Conflicts, and Living With Multiple Layers of Betrayal--emerged. The pattern and themes portray the very complex and challenging experiences faced by these young women living with HIV infection. They have experienced isolation, abandonment, betrayal, and discrimination in their interpersonal and social systems. They often dealt with conflicts of hope and anguish in the relationships with their children, and portraying strength, while feeling fragile. These complexities negatively influence the ability to fully engage in self-care activities. Implications for future research include further investigation about the experiences of psychological distress experienced post-diagnosis, development and evaluation of holistic nursing interventions, and evaluative research on mass media educational campaigns to reduce HIV-related stigma. PMID:25239137

  6. Field Report on the iMUSH Active Source Seismic Experiment

    NASA Astrophysics Data System (ADS)

    Kiser, E.; Levander, A.; Schmandt, B.; Palomeras, I.; Harder, S. H.; Creager, K. C.; Vidale, J. E.; Malone, S. D.

    2014-12-01

    In the second half of July we completed the iMUSH active source seismic experiment, one component of the Imaging Magma Under Saint Helens project. A team of ~75 volunteers deployed 3500 seismographs to ~5920 locations on and around Mount St. Helens over the course of 3 weeks. This instrument deployment was accompanied by 23 shots distributed around the volcano. Instrumentation consisted of ~2550 Reftek 125A (Texan) seismographs with 4.5 Hz geophones, and 920 Nodal Seismic recorders with 10 Hz geophones. The shots were also recorded by the permanent stations of the Pacific Northwest Seismograph Network and 70 iMUSH broadband seismographs. Fifteen of the shots, 424 kg each, formed two rings around Mount Saint Helens at 15 km and 30 km radius from the summit. Eight of the shots, 828 kg each, were fired at distances of 50 to 80 km from MSH on NW-SE and NE-SW azimuths. The deployment geometry consisted of two lines oriented NW/SE and NE/SW, and three arrays. The offset of the lines ranged from 150 km to 190 km with an average spacing of 200 m. The first array was centered on the volcano with a radius of 30 km, and required both driving and hiking to deploy. Arrays two and three were set out with, and centered on, the NW/SE line. These arrays had a distance range from MSH of 30-75 km and an azimuth range of about 100 degrees. In addition to this large-scale deployment, we set out 7 beamforming arrays approximately collocated with iMUSH broadband seismographs, and above clusters of seismicity in the region. The aperture of these arrays was about 1 km with an instrument spacing of 100 m. The final deployment ended only days before the AGU abstract deadline, so we have not yet examined all of the data. However, the preliminary indications are that signal to noise is excellent: The shots, several of which registered on PNSN as ML>2.1, carried across the entire array, and were recorded as far away as Seattle and Corvallis on permanent stations. The array also recorded a

  7. A study of the lived experiences of African American women STEM doctoral degree completers

    NASA Astrophysics Data System (ADS)

    Squires, Stephanie Michelle

    This study examined the lived experiences of African American women (AAW) who completed doctoral degrees in a STEM (science, technology, engineering, and mathematics) discipline in the United States. This study sought to fill the gap in the literature by examining how AAW described and made meaning of lived STEM educational experiences during doctoral degree completion in the context of the intersection of being African American and a woman. This study utilized a theoretical perspective based upon three theories: (a) critical race theory as a framework to gather AAW's narratives about STEM doctorate education, (b) Black feminist thought as a framework to view the intersection of being African American and a woman in the United States, and (c) the science identity model as a framework to view how women of color successfully complete scientific graduate degrees. Participants revealed that being an African American and a woman in a STEM doctoral program often complicated an already difficult process of completing the doctoral degree. The participants described the educational experience as challenging, particularly the writing of the dissertation. The challenges that the participants faced were due to various factors such as difficult advisor/advisee relationships, tedious writing and revision processes, politics, and lack of information regarding the doctoral degree process. The findings suggested that AAW participants confronted intrinsic bias while completing STEM doctoral degrees, which led to isolation and feelings of being an impostor---or feelings of not belonging in scientific studies. The findings also indicated that the women in this study ascribed success in dissertation writing and degree completion to one or more of the following attributes: (a) having a clear plan, (b) taking ownership of the writing process, (c) having an engaged advisor, (d) learning the writing style of the advisor, (e) understanding the temperament of the advisor, (f) personal will

  8. South Africans' experiences of being old and of care and caring in a transitional period.

    PubMed

    Bohman, Doris M; van Wyk, Neltjie C; Ekman, Sirkka-Liisa

    2011-09-01

    This focused ethnographic study aimed to illuminate a group of South Africans' experiences of being old and of care and caring in a transitional period. With a growing number of older people in Africa, studies on the individual experiences may help to develop care which is more sensitively based on the needs for older people in a changing Southern Africa context. Data were collected through group and individual in-depth interviews and participant observations which involved 16 individuals, aged 52-76. Data were analysed using a qualitative content analysis. The study showed two interrelated themes reflections on life and ubuntu - an orientation towards others. Findings were discussed from the viewpoint of the theory of gerotranscendence, showing similarities as well as differences, possibly due to societal and cultural differences. Shortage of formal care for older people living in poor conditions in Southern Africa, gave rise to the discussion for the need of a contextualized development of gerontological care. To enhance knowledge on the theory of gerotranscendence and develop guidelines for nursing in home-based care/community-based care in a South African context may be a first step to support older people in their process towards gerotranscendence. PMID:21631870

  9. Experiences of racist events are associated with negative health consequences for African American women.

    PubMed Central

    Kwate, Naa Oyo A.; Valdimarsdottir, Heiddis B.; Guevarra, Josephine S.; Bovbjerg, Dana H.

    2003-01-01

    This study investigated whether experiences of racist events were related to psychological distress, negative health behaviors, and health problems. Participants were 71 African American women (mean age 44.4) who were recruited from an urban cancer-screening clinic as part of a larger longitudinal study on familial risk of breast cancer. Participants completed three study assessments, approximately one month apart, and data were collected via self-report. Correlational analyses revealed that past year and lifetime racism were both related to psychological distress. Among smokers and drinkers, past year racism was positively correlated with number of cigarettes and drinks consumed. Lifetime racism was negatively related to perceived health, and positively related to lifetime history of physical disease and frequency of recent common colds. Analyses using a general linear model revealed that these relationships were largely unaccounted for by other variables. In addition, demographic variables such as income and education were not related to experiences of racism. The results suggest that racism can be detrimental to African American's well being and should be investigated in health disparities research. PMID:12856911

  10. Racism at the intersections: Gender and socioeconomic differences in the experience of racism among African Americans.

    PubMed

    Kwate, Naa Oyo A; Goodman, Melody S

    2015-09-01

    Several studies investigating the health effects of racism have reported gender and socioeconomic differences in exposures to racism, with women typically reporting lower frequencies, and individuals with greater resources reporting higher frequencies. This study used diverse measures of socioeconomic position and multiple measures and methods to assess experienced racism. Socioeconomic position included education and financial and employment status. Quantitative racism measures assessed individual experiences with day-to-day and with major lifetime incidents and perceptions of the extent to which African Americans as a group experience racism. A brief qualitative question asked respondents to describe a racist incident that stood out in recent memory. Participants comprised a probability sample of N = 144 African American adults aged 19 to 87 residing in New York City. Results suggested that women reported fewer lifetime incidents but did not differ from men on everyday racism. These differences appear to be partly because of scale content. Socioeconomic position as measured by years of education was positively associated with reported racism in the total sample but differently patterned across gender; subjective social status showed a negative association. Qualitative responses describing memorable incidents fell into 5 key categories: resources/opportunity structures, criminal profiling, racial aggression/assault, interpersonal incivilities, and stereotyping. In these narratives, men were more likely to offer accounts involving criminal profiling, and women encountered incivilities more often. The findings highlight the need for closer attention to the intersection of gender and socioeconomic factors in investigations of the health effects of racism. PMID:26460700

  11. African American women's preventative care usage: the role of social support and racial experiences and attitudes.

    PubMed

    Pullen, Erin; Perry, Brea; Oser, Carrie

    2014-09-01

    Research suggests that African Americans are less likely to utilise preventative care services than Americans of European descent, and that these patterns may contribute to racial health disparities in the United States. Despite the persistence of inequalities in preventative care utilisation, culturally relevant factors influencing the use of these gateway health services have been understudied among marginalised groups. Using a stratified sample of 205 low-income African American women, this research examines the predictors of receiving a physical exam, with a particular emphasis on how differing levels of social support from friend and family networks and experiences of racial discrimination and cultural mistrust shape utilisation. The findings underscore the importance of traditional predictors of utilisation, including insurance status and having a usual physician. However, they also indicate that supportive ties to friendship networks are associated with higher predicted rates of having an annual physical exam, while social support from family and sentiments of cultural mistrust are associated with lower rates of utilisation. Broadly, the findings indicate that even as traditional predictors of help-seeking become less relevant, it will be critical to explore how variations in discrimination experiences and social relationships across marginalised groups drive patterns of preventative care utilisation. PMID:24749849

  12. "I Want to Do the Right Thing but What Is It?": White Teachers' Experiences with African American Students

    ERIC Educational Resources Information Center

    Henfield, Malik S.; Washington, Ahmad R.

    2012-01-01

    This qualitative study examines 26 White middle school teachers' perceptions of their experiences in a predominantly White middle school with a growing African American student population. Utilizing in-depth focus group interviews, teachers elaborated on their experiences with navigating racial, ethnic and cultural boundaries as they attempted to…

  13. Victimization Experiences, Substance Misuse and Mental Health Problems in Relation to Risk for Lethality among African-American and African-Caribbean Women

    PubMed Central

    Sabri, Bushra; Stockman, Jamila K.; Betrand, Desiree; Campbell, Doris W.; Callwood, Gloria B.; Campbell, Jacquelyn C.

    2013-01-01

    The purpose of this study was to investigate the association of intimate partner victimization experiences, mental health, and substance misuse problems with the risk for lethality among women of African descent. Data for this cross-sectional study were derived from a large case-control study examining the relationship between abuse status and health consequences. Women were recruited from primary care, prenatal or family planning clinics in Baltimore and the US Virgin Islands. Logistic regression was used to generate the study findings. Among 543 abused women, physical and psychological abuse by intimate partners, comorbid PTSD and depression symptoms, and PTSD-only problems significantly increased the likelihood of lethality risk. However victims’ substance misuse and depression-only problems were not associated with the risk for lethality. Additionally, PTSD symptoms mediated the relationship between severe victimization experiences and risk for lethality. Practitioners should pay attention to victimization experiences and mental health issues when developing treatment and safety plans. Policies to fund integrated services for African-American and African-Caribbean women with victimization and related mental health issues, and training of providers to identify at-risk women may help reduce the risk for lethality in intimate partner relationships. PMID:23929602

  14. Seismic Anisotropy of the Lithosphere/Asthenosphere System Beneath the Rwenzori Region of the East-African Rift

    NASA Astrophysics Data System (ADS)

    Homuth, B.; Löbl, U.; Batte, A.; Link, K.; Kasereka, C.; Rumpker, G.

    2014-12-01

    We present results from a temporary seismic network of 32 broad-band stations located around the Rwenzori region of the Albertine rift at the border between Uganda and DR Congo. The study aims to constrain seismic anisotropy and mantle deformation processes in relation to the formation of the rift zone. Shear-wave splitting measurements from local and teleseismic earthquakes are used to investigate the seismic anisotropy in the crust and upper mantle beneath the Rwenzori region. At most stations, shear-wave splitting parameters obtained from individual earthquakes exhibit only minor variations with backazimuth. We therefore employ a joint inversion of SKS waveforms to derive hypothetical one-layer parameters. The corresponding fast polarizations are generally rift-parallel and the average delay time is about 1 s. On the other hand, shear phases from local events within the crust are characterized by an average delay time of 0.04 s. This observation suggests that the dominant source region for seismic anisotropy beneath the rift is located within the mantle. We use finite-frequency waveform modeling to test different models of anisotropy within the lithosphere/asthenosphere system of the rift. The results show that the rift-parallel fast polarizations are consistent with HTI anisotropy caused by magmatic intrusions or lenses located within the lithospheric mantle - as it would be expected during the early stages of continental rifting. Furthermore, the short-scale spatial variations in the fast polarizations observed in the southern part of the study area can be explained by effects due to sedimentary basins of low isotropic velocity in combination with a shift in the orientation of anisotropic fabrics in the upper mantle. A uniform anisotropic layer in relation to large-scale asthenospheric mantle flow is less consistent with the observed splitting parameters.

  15. Seismic anisotropy of the lithosphere/asthenosphere system beneath the Rwenzori region of the East-African Rift

    NASA Astrophysics Data System (ADS)

    Homuth, Benjamin; Löbl, Ulrike; Batte, Arthur; Link, Klemens; Kasereka, Celestine; Rümpker, Georg

    2014-05-01

    We present results from a temporary seismic network of 32 broad-band stations located around the Rwenzori region of the Albertine rift at the border between Uganda and DR Congo. The study aims to constrain seismic anisotropy and mantle deformation processes in relation to the formation of the rift zone. Shear-wave splitting measurements from local and teleseismic earthquakes are used to investigate the seismic anisotropy in the crust and upper mantle beneath the Rwenzori region. At most stations, shear-wave splitting parameters obtained from individual earthquakes exhibit only minor variations with backazimuth. We therefore employ a joint inversion of SKS waveforms to derive hypothetical one-layer parameters. The corresponding fast polarizations are generally rift-parallel and the average delay time is about 1 s. On the other hand, shear phases from local events within the crust are characterized by a bimodal pattern of fast polarizations and an average delay time of 0.04 s. This observation suggests that the dominant source region for seismic anisotropy beneath the rift is located within the mantle. We use finite-frequency waveform modeling to test different models of anisotropy within the lithosphere/asthenosphere system of the rift. The results show that the rift-parallel fast polarizations are consistent with HTI anisotropy caused by rift-parallel magmatic intrusions or lenses located within the lithospheric mantle - as it would be expected during the early stages of continental rifting. Furthermore, the short-scale spatial variations in the fast polarizations observed in the southern part of the study area can be explained by effects due to sedimentary basins of low isotropic velocity in combination with a shift in the orientation of anisotropic fabrics in the upper mantle. A uniform anisotropic layer in relation to large-scale asthenospheric mantle flow is less consistent with the observed splitting parameters.

  16. It Just Couldn't Have Been Our School: A Phenomenological Study of the Schooling Experiences of African American Male Inmates.

    ERIC Educational Resources Information Center

    Terrell, Shandra R.

    The school experiences of African American male inmates are explored. Nine African American male inmates, ranging in age from 21 to 55, were interviewed regarding their schooling experiences. Interviews were recorded and transcribed to create a text, and themes were uncovered. Themes that describe their schooling experiences were identified. Four…

  17. Multichannel seismic-reflection profiling on the R/V Maurice Ewing during the Los Angeles Region Seismic Experiment (LARSE), California

    USGS Publications Warehouse

    Brocher, Thomas M.; Clayton, Robert W.; Klitgord, Kim D.; Bohannon, Robert G.; Sliter, Ray; McRaney, John K.; Gardner, James V.; Keene, J.B.

    1995-01-01

    This report describes the acquisition of deep-crustal multichannel seismic-reflection data in the Inner California Borderland aboard the R/V Maurice Ewing, conducted in October 1994 as part of the Los Angeles Regional Seismic Experiment (LARSE). LARSE is a cooperative study of the crustal structure of southern California involving earth scientists from the U.S. Geological Survey, Caltech, the University of Southern California, the University of California Los Angeles, and the Southern California Earthquake Center (SCEC). During LARSE, the R/V Ewing's 20- element air gun array, totaling 137.7 liters (8470 cu. in.), was used as the primary seismic source for wide-angle recording along three main onshore-offshore lines centered on the Los Angeles basin and the epicenters of the 1933 Long Beach and 1994 Northridge earthquakes. The LARSE onshore-offshore lines were each 200-250 km long, with the offshore portions being between 90 and 150 km long. The nearly 24,000 air gun signals generated by the Ewing were recorded by an array of 170 PASSCAL REFTEK recorders deployed at 2 km intervals along all three of the onshore lines and 9 ocean bottom seismometers (OBSs) deployed along two of the lines. Separate passes over the OBS-deployment lines were performed with a long air gun repetition rate (60 and 90 seconds) to minimize acoustic-wave interference from previous shots in the OBS data. The Ewing's 4.2-km, 160-channel, digital streamer was also used to record approximately 1250 km of 40-fold multichannel seismic-reflection data. To enhance the fold of the wide-angle data recorded onshore, mitigating against cultural and wind noise in the Los Angeles basin, the entire ship track was repeated at least once resulting in fewer than about 660 km of unique trackline coverage in the Inner Borderland. Portions of the seismic-reflection lines were repeated up to 6 times. A variety of other geophysical data were also continuously recorded, including 3.5 kHz bathymetry, multi

  18. ENAM: A community seismic experiment targeting rifting processes and post-rift evolution of the Mid Atlantic US margin

    NASA Astrophysics Data System (ADS)

    Van Avendonk, H. J.; Magnani, M. B.; Shillington, D. J.; Gaherty, J. B.; Hornbach, M. J.; Dugan, B.; Long, M. D.; Lizarralde, D.; Becel, A.; Benoit, M. H.; Harder, S. H.; Wagner, L. S.; Christeson, G. L.

    2014-12-01

    The continental margins of the eastern United States formed in the Early Jurassic after the breakup of supercontinent Pangea. The relationship between the timing of this rift episode and the occurrence of offshore magmatism, which is expressed in the East Coast Magnetic Anomaly, is still unknown. The possible influence of magmatism and existing lithospheric structure on the rifting processes along margin of the eastern U.S. was one of the motivations to conduct a large-scale community seismic experiment in the Eastern North America (ENAM) GeoPRISMS focus site. In addition, there is also a clear need for better high-resolution seismic data with shallow penetration on this margin to better understand the geological setting of submarine landslides. The ENAM community seismic experiment is a project in which a team of scientists will gather both active-source and earthquake seismic data in the vicinity of Cape Hatteras on a 500 km wide section of the margin offshore North Carolina and Virginia. The timing of data acquisition in 2014 and 2015 facilitates leveraging of other geophysical data acquisition programs such as Earthscope's Transportable Array and the USGS marine seismic investigation of the continental shelf. In April of 2014, 30 broadband ocean-bottom seismometers were deployed on the shelf, slope and abyssal plain of the study site. These instruments will record earthquakes for one year, which will help future seismic imaging of the deeper lithosphere beneath the margin. In September and October of 2014, regional marine seismic reflection and refraction data will be gathered with the seismic vessel R/V Marcus Langseth, and airgun shots will also be recorded on land to provide data coverage across the shoreline. Last, in the summer of 2015, a land explosion seismic refraction study will provide constraints on the crustal structure in the adjacent coastal plain of North Carolina and Virginia. All seismic data will be distributed to the community through IRIS

  19. The Source Physics Experiments and Advances in Seismic Explosion Monitoring Predictive Capabilities

    NASA Astrophysics Data System (ADS)

    Walter, W. R.; Ford, S. R.; Antoun, T.; Pitarka, A.; Xu, H.; Vorobiev, O.; Rodgers, A.; Pyle, M. L.

    2012-12-01

    Despite many years of study, a number of seismic explosion phenomena remain incompletely understood. These include the generation of S-waves, the variation of absolute amplitudes with emplacement media differences, and the occasional generation of reversed Rayleigh waves. Advances in numerical methods and increased computational power have improved the physics contained in the modeling software and it is possible to couple non-linear source-region effects to far-field propagation codes to predict seismic observables, thereby allowing end-to-end modeling. However, despite the many sensor records from prior nuclear tests, the data available to develop and validate the simulation codes remain limited in important ways. This is particularly the case for the range of both scaled depths of burial and of source media, especially where full near-field to far-field records are available along with key quantitative parameter data such as depth, material properties and yield. For example, two of the most widely used seismic source models, both derived from the best empirical data, Mueller and Murphy (1971) and Denny and Johnson (1989), predict very different amplitudes for greatly overburied explosions. To provide new data to advance predictive explosion modeling capabilities, the National Nuclear Security Administration (NNSA) is carrying out a series of seven chemical explosions over a range of depths and sizes in the Source Physics Experiments (SPE). These shots are taking place in the Climax Stock granite at the Nevada National Security Site, the location where reversed Rayleigh waves from a nuclear test were first observed in the 1962 HARDHAT event (e.g. Brune and Pomeroy, 1963). Three of the SPE shots have successfully occurred so far, and were well-recorded by an extensive set of instrumentation including seismic, acoustic, EM, and remote sensing. In parallel, detailed site characterization has been conducted using geologic mapping and sampling, borehole geophysics

  20. Passive Seismic Experiment "13 BB Star" in the Margin of the East European Craton, Northern Poland

    NASA Astrophysics Data System (ADS)

    Polkowski, M.; Grad, M.; Wilde-Piórko, M.; Suchcicki, J.; Arant, T.

    2014-12-01

    Passive experiment "13 BB star" is dedicated to study deep structure of the Earth's interior in the marginal zone of the East European Craton in northern Poland. The seismic network consists of 13 broadband stations on the area of c. 120 km in diameter. The network is located in the area well recognized from the point of view velocities of sedimentary cover and crustal structure. Good records obtained since summer 2013, and expected during next 1.5 years long recording campaign, should yield images of detailed structure of the lithosphere-asthenosphere boundary (LAB), „410", "?520", and „660" km discontinuities, as well as mantle-core boundary and inner core. The LAB is investigated recently very effectively, mostly using seismic methods because their deep penetration and relatively good resolution. The nature of LAB is still debated, particularly under "cold" Precambrian shields and platforms. We show examples of local and teleseismic records, array transfer function of "13 BB star" network and preliminary noise analysis. National Science Centre Poland provided financial support for this work by NCN grant DEC- 2011/02/A/ST10/00284.

  1. High-resolution shallow-seismic experiments in sand. Part 2: Velocities in shallow unconsolidated sand

    SciTech Connect

    Bachrach, R.; Dvorkin, J.; Nur, A.

    1998-07-01

    The authors conducted a shallow high-resolution seismic reflection and refraction experiment on a sandy beach. The depth of investigation was about 2 m. They interpret the data using the Hertz-Mindlin contact theory combined with Gassmann`s equation. These were used to obtain the vertical velocity profile. Then the profile was computed from seismic data using the turning-rays approximation. The normal moveout (NMO) velocity at the depth of 2 m matches the velocity profile. As a result, they developed a method to invert measured velocity from first arrivals, i.e., velocity versus distance into velocity versus depth using only one adjustable parameter. This parameter contains all the information about the internal structure and elasticity of the sand. The lowest velocity observed was about 40 m/s. It is noteworthy that the theoretical lower bound for velocity in dry sand with air is as low as 13 m/s. The authors find that modeling sand as a quartz sphere pack does not quantitatively agree with the measured data. However, the theoretical functional form proves to be useful for the inversion.

  2. A comparative study of seismicity statistics in laboratory stick-slip experiments and nature: Implications for fault mechanics

    NASA Astrophysics Data System (ADS)

    Goebel, Thomas; Kwiatek, Grzegorz; Becker, Thorsten; Sammis, Charles; Dresen, Georg

    2016-04-01

    Fault properties can rarely be monitored under in-situ conditions at seismogenic depth. At these depths seismicity records are possibly the only high-resolution data that can provide insight into state of stress and mechanics of faulting. We analyze series of laboratory experiments on faults that developed during stick-slip on saw-cut and fractured surfaces under upper crustal stress conditions. Stick-slip experiments were performed on surfaces with varying roughness and fracture surfaces that evolved into fault zones with pronounced damage zones. We monitor and analyze acoustic emission events that exhibit many striking similarities to natural seismicity across all examined scales. These similarities include pronounced Gutenberg-Richter-type magnitude distributions, Omori-type aftershock decay, and off-fault seismicity distributions that decay as a power law with distance. In the laboratory, fault roughness and heterogeneity are critical in concentrating stresses that lead to local AE clustering, and differences in off-fault activities and lower b-values. Similar observations of earthquake clustering and b-value variations were made for natural faults such as the Parkfield segment of the San Andreas fault. In addition to seismicity statistics, we conducted a detailed analysis of moment tensors, focusing on relative contributions from isotropic and deviatoric components to laboratory seismicity. In contrast to natural seismicity, our results revealed a larger contribution from isotropic components. These contributions are a result of ongoing fracture processes within the evolving fault which are most pronounced after stick-slip events. Our study shows, that seismicity analyses in laboratory experiments can significantly advance our understanding of fault mechanics from the scale of single asperities to large fault zones.

  3. On the scalability of seismic waveform inversion: From ultrasonic experiments to global-scale tomography

    NASA Astrophysics Data System (ADS)

    Kamei, R.; Pratt, R. G.

    2012-12-01

    Seismic waveform inversion endeavors to extract high-resolution subsurface models from full seismic records by using numerical solutions of the full forward wave equation. In the last two decades, waveform inversion has been successfully applied to both active and passive seismic experiments, and has demonstrated superb resolution power over a wide-range of applications. Waveform inversion is still computationally challenging, and is well known to be a strongly non-linear and ill-conditioned inverse problem. Passive and active waveform inversions have largely been developed independently, although both originate from the work of Lailly (1983) and Tarantola (1984). In this presentation, we review a suite of past results from both active and passive source waveform inversions, and attempt to illustrate similarities and shared challenges between them. In active seismics, waveform inversion has been applied to i) ultrasonic breast cancer data to image targets of a few tens of centimeters on a side, ii) cross-well exploration data using frequencies between hundreds and a few thousands of Hz to image targets of the order of hundreds of meters on a side, iii) surface seismic for near-surface engineering problems using frequencies of tens to a few hundreds of Hz to image targets of the order of hundreds of meters to several kilometers, and iv) hydrocarbon exploration and crustal imaging using frequencies of a few, to a few tens of Hz for targets tens of kilometers on a side. In contrast, waveform inversion from passive source data uses much lower frequencies (less than 1 Hz), and images much larger target areas to retrieve iv) crustal scale structures of the order of hundreds of kilometers using data periods of one to several tens of seconds, v) upper-mantle structure on regional scales thousands of kilometers on a side using data periods of ten to a few hundred seconds, and vi) the whole-earth inversions (of order 10,000 km on a side), using a similar frequency range. Our

  4. Early-stage rifting in the southwest East African Rift: Insights from new reflection seismic data from Lakes Tanganyika and Malawi (Nyasa)

    NASA Astrophysics Data System (ADS)

    Scholz, C. A.; Wood, D. A.; Shillington, D. J.; McCartney, T.; Accardo, N. J.

    2015-12-01

    The western branch of the East African Rift is characterized by modest amounts of mainly amagmatic extension; deeply-subsided, fault-controlled basins; and large-magnitude, deep seismicity. Lakes Tanganyika and Malawi are two of the world's largest lakes, with maximum water depths of 1450 and 700 m respectively. Newly acquired seismic reflection data, along with newly reprocessed legacy data reveal thick sedimentary sections, in excess of 5 km in some localities. The 1980's vintage legacy data from Project PROBE have been reprocessed through pre-stack depth migration in Lake Tanganyika, and similar reprocessing of legacy data from Lake Malawi is forthcoming. New high-fold and large-source commercial and academic data have recently been collected in southern Lake Tanganyika, and in the northern and central basins of Lake Malawi as part of the 2015 SEGMeNT project. In the case of Lake Tanganyika, new data indicate the presence of older sediment packages that underlie previously identified "pre-rift" basement (the "Nyanja Event"). These episodes of sedimentation and extension may substantially predate the modern lake. These deep stratal reflections are absent in many localites, possibly on account of attenuation of the acoustic signal. However in one area of southern Lake Tanganyika, the newly-observed deep strata extend axially for ~70 km, likely representing deposits from a discrete paleolake. The high-amplitude Nyanja Event is interpreted as the onset of late-Cenozoic rifting, and the changing character of the overlying depositional sequences reflects increasing relief in the rift valley, as well as the variability of fluvial inputs, and the intermittent connectivity of upstream lake catchments. Earlier Tanganyika sequences are dominated by shallow lake and fluvial-lacustrine facies, whereas later sequences are characterized by extensive gravity flow deposition in deep water, and pronounced erosion and incision in shallow water depths and on littoral platforms. The

  5. Factors Associated with Partnership Experiences, Attitudes, and Perceptions: A Comparative Case Study of Two African Universities

    ERIC Educational Resources Information Center

    Chiteng Kot, Felly

    2011-01-01

    International partnerships have become an increasingly important trend in African higher education. The creation of partnerships with African universities has been on the rise in the last few years. Different factors (U.S., European, and African initiatives) suggest this trend will continue to increase. This study draws from a survey of a random…

  6. Contributions of College Experiences to African American and White Graduates' Careers.

    ERIC Educational Resources Information Center

    Nickols, Sharon Y.; And Others

    1996-01-01

    A survey of housing/consumer economics and social work alumni received responses from 38 African American and 50 white graduates. Likely sources of financial support for whites were parents, and for African Americans, grants. African Americans had significantly higher social support from churches, whites from sororities/fraternities. There were no…

  7. The South African Experience of Conservation and Social Forestry Outreach Nurseries

    NASA Astrophysics Data System (ADS)

    Botha, Jenny; Witkowski, Ed T. F.; Cock, Jacklyn

    2006-11-01

    Outreach nurseries are favored conservation and social forestry tools globally, but, as with many integrated conservation and development programs (ICDPs), they do not always produce anticipated results. A synopsis of the experience of South African practitioners is provided in this study of 65 outreach nurseries. South African outreach nurseries frequently include financial objectives, creating additional challenges in simultaneously attaining conservation and socioeconomic goals. Progress was hindered by biophysical problems (e.g., lack of water, poor soils, etc.) as well as the harsh socioeconomic conditions facing most communities in which nurseries had been established. Attaining financial viability was challenging. Business management skills were often restricted, and few viability studies included adequate market research. Costs to community participants were usually high, and benefits were limited. Conservation objectives were frequently lost in the struggle to attain financial viability. The management of social processes also proved challenging. Although small scale and relatively straightforward compared with many ICDPs, nurseries usually require substantial institutional support, including a range of technical, business, and development services. Project time frames need to be reconsidered, as practitioners estimate that it takes 5-10 years for nurseries to start meeting objectives, and donors and implementing agencies often operate on 2-3-year project cycles. Detailed viability studies are essential, incorporating a social probe and an assessment of potential impacts of projects on community participants. Progress needs to be continuously evaluated to enable institutions and community participants to adapt to changing conditions as well as ensure that the spectrum of objectives are being achieved.

  8. Comparison of Abuse Experiences of Rural and Urban African American Women During Perinatal Period

    PubMed Central

    Bhandari, Shreya; Bullock, Linda F. C.; Richardson, Jeanita W.; Kimeto, Pamela; Campbell, Jacquelyn C.; Sharps, Phyllis W.

    2015-01-01

    A subsample of 12 African American women (6 urban and 6 rural) were selected from a larger longitudinal, randomized control trial, Domestic Violence Enhanced Home Visitation (DOVE-R01 900903 National Institute of Nursing Research [NINR]/National Institutes of Health [NIH]). All African American women were chosen to control for any racial- and/or race-related cultural differences that may exist among women across geographical areas. The experiences of abuse during the perinatal period are drawn from in-depth interviews conducted at five points in time during pregnancy and the post-partum period. The analysis describes three major themes that highlight the similarities and differences among rural and urban women. The main themes found were (1) types of abuse, (2) location of abuse, and (3) response to abuse. In addition, two sub-themes (a) defiance and compliance and (b) role of children were also identified. Implications for universal screening for women of reproductive age, safer gun laws, and the need for further research are discussed. PMID:25315478

  9. Comparison of abuse experiences of rural and urban African American women during perinatal period.

    PubMed

    Bhandari, Shreya; Bullock, Linda F C; Richardson, Jeanita W; Kimeto, Pamela; Campbell, Jacquelyn C; Sharps, Phyllis W

    2015-07-01

    A subsample of 12 African American women (6 urban and 6 rural) were selected from a larger longitudinal, randomized control trial, Domestic Violence Enhanced Home Visitation (DOVE-R01 900903 National Institute of Nursing Research [NINR]/National Institutes of Health [NIH]). All African American women were chosen to control for any racial- and/or race-related cultural differences that may exist among women across geographical areas. The experiences of abuse during the perinatal period are drawn from in-depth interviews conducted at five points in time during pregnancy and the post-partum period. The analysis describes three major themes that highlight the similarities and differences among rural and urban women. The main themes found were (1) types of abuse, (2) location of abuse, and (3) response to abuse. In addition, two sub-themes (a) defiance and compliance and (b) role of children were also identified. Implications for universal screening for women of reproductive age, safer gun laws, and the need for further research are discussed. PMID:25315478

  10. Regulatory challenges for GM crops in developing economies: the African experience.

    PubMed

    Nang'ayo, Francis; Simiyu-Wafukho, Stella; Oikeh, Sylvester O

    2014-12-01

    Globally, transgenic or genetically modified (GM) crops are considered regulated products that are subject to regulatory oversight during trans-boundary movement, testing and environmental release. In Africa, regulations for transgenic crops are based on the outcomes of the historic Earth Summit Conference held in Rio, Brazil two decades ago, namely, the adoption of the Convention on Biological Diversity (CBD) and the subsequent adoption of the Cartagena Protocol on Biosafety. To exploit the potential benefits of transgenic crops while safeguarding the potential risks on human health and environment, most African countries have signed and ratified the CBD and the Cartagena Protocol on Biosafety. Consequently, these countries are required to take appropriate legal, administrative and other measures to ensure that the handling and utilization of living modified organisms are undertaken in a manner that reduces the risks to humans and the environment. These countries are also expected to provide regulatory oversight on transgenic crops through functional national biosafety frameworks (NBFs). While in principle this approach is ideal, NBFs in most African countries are steeped in a host of policy, legal and operational challenges that appear to be at cross-purposes with the noble efforts of seeking to access, test and deliver promising GM crops for use by resource-limited farmers in Africa. In this paper we discuss the regulatory challenges faced during the development and commercialization of GM crops based on experiences from countries in Sub-Saharan Africa. PMID:24821674

  11. DHOFAR Seismic Experiment: First results to understand the breakup processes in a passive margin context

    NASA Astrophysics Data System (ADS)

    Tiberi, C.; Leroy, S.; D'Acremont, E.; Pointu, A.; Ebinger, C.; Brisbourne, A.; Denton, P.; Al-Lazki, A.; Al-Azri, H.; Bin Monshir Bahlaf, S.; Brunet, C.; Famin, V.; Labrousse, L.

    2004-12-01

    The process of strain localisation preceding the onset of seafloor spreading is still poorly understood, though extensively studied. The reason is the differences in lithospheric properties, proximity to hot spot(s) and melt generation and extraction that lead to a variety of structural styles with major differences. The eastern Gulf of Aden represents a natural laboratory to study passive continental margins for many reasons: post-rift sedimentary strata are relatively thin, both onshore and nearshore structures are well-exposed, and conjugate margins can be precisely reconstructed. A first cruise (ENCENS-SHEBA), in 2000, has established the structural and geophysical framework using bathymetric swath mapping and underway geophysics. Later on, the Dhofar seismic experiment consisted in the deployment of a network of 11 broadband seismic stations from March 2003 to March 2004 on the northern margin, in the Dhofar area, southern Oman. This experiment was dedicated to the detailed study of the crust and upper mantle beneath the northern passive margin. CMG40TD 3-components seismometers from SEIS-UK network were used. We have recorded hundreds of teleseismic events with a good azimuthal coverage. Three main studies are then attempted. First, a teleseismic image of the first 200 km depth will be established using the P- and PKP-phases. This will allow a 3D representation of crustal and upper mantle velocity structures. We present here the preliminary results from the study of the traveltime residuals. The image resolution shall be enhanced by combining gravity data. Second, a receiver function analysis will locally determine the depth of the main interfaces (eg, Moho boundary). Finally, events recorded within the 1000-6000 km distance range will improve the regional S-wave velocity structure in this area and will help to locate the main regional wide structures related to this extended area.

  12. Problematic situations associated with dating experiences and relationships among urban African American adolescents: a qualitative study.

    PubMed

    Sullivan, Terri N; Erwin, Elizabeth H; Helms, Sarah W; Masho, Saba W; Farrell, Albert D

    2010-12-01

    This qualitative study focused on the identification of problem situations associated with adolescent dating experiences and relationships, including those that placed youth at risk for dating violence perpetration or victimization. Interviews were conducted with 44 African American middle and high school students in an urban school system. Qualitative analysis identified 18 individual themes representing six categories of problem situations: (a) approach and initiation; (b) conflict, conflict resolution, and break-ups; (c) communication, connection, and emotion; (d) aggression and victimization; (e) the role of others; and (f) media and technology. Identification of these problem situation themes has important implications for developing and evaluating prevention efforts designed to foster healthy adolescent dating relationships. PMID:20931286

  13. Early educational foundations for the development of civic responsibility: an African experience.

    PubMed

    Serpell, Robert; Mumba, Paul; Chansa-Kabali, Tamara

    2011-01-01

    An innovative curriculum designed to foster the development of social responsibility among pre-adolescent children was introduced at a rural Zambian primary school. The curriculum invoked Child-to-Child principles focusing on health education, advancing a synthesis of Western psychological theories and African cultural traditions. The teacher sought to democratize the educational process through cooperative learning in mixed-gender, mixed-social-class, and mixed-ability study groups. Learners engaged in community service activities and contributed to the nurturant care of younger children. Young adults interviewed seventeen years after completing the program recalled their experience and reflected on how it had promoted their personal agency, cooperative disposition, and civic responsibility in early adulthood. PMID:22147602

  14. “I thought we are safe”: Southern African lesbians' experiences of living with HIV

    PubMed Central

    Matebeni, Zethu; Reddy, Vasu; Sandfort, Theo; Southey-Swartz, Ian

    2013-01-01

    HIV prevention and service programmes have long either ignored or overlooked lesbians. The experiences of lesbians with HIV have similarly been unrecognised and unreported. This erasure has contributed to the invisibility of lesbians in relation to HIV and related health risks. This community participatory study, based on in-depth interviews with twenty-four self-identifying African lesbians living with HIV in South Africa, Zimbabwe and Namibia, focuses on their personal experiences and circumstances. Women's experiences shed light and challenge popular notions around lesbian risk. In particular among this group are lesbians who self-report exclusive sexual relationships with women. For these women, experiences of living with HIV are challenging as they struggle to understand the possibility of female-to-female transmission. While battling with their own perceptions of invulnerability and accepting their HIV positive status, they have to deal also with wide-ranging misconceptions about risk. The paper argues that within the context of HIV lesbians cannot be regarded as a `no-risk' group. Health services and health providers are encouraged to respond to the health needs of lesbians living with HIV. PMID:23627778

  15. A Case Study: How Do Social and Academic Experiences of African American Nontraditional Female Students on HBCU Campuses Influence Their Motivation to Graduate?

    ERIC Educational Resources Information Center

    Jackson-Golden, Cheryl D.

    2013-01-01

    Through a qualitative collective case study research design, the study captured the social and academic experiences of 13 African American nontraditional undergraduate female students enrolled in a historically Black college campus (HBCU) located in the southern United States. Experiences of 13 African American nontraditional undergraduate female…

  16. Schooling Experiences and Perceptions of Resettled Sub-Saharan African Refugee Middle School Students in a Southwest U.S. State

    ERIC Educational Resources Information Center

    Sallu, Adama

    2012-01-01

    This study examined the schooling experiences and perceptions of resettled sub-Saharan African middle school refugee students in a metropolitan area of the United States Southwest. The research questions underpinning this study included: What are the schooling experiences and perceptions of resettled sub-Saharan African middle school refugee…

  17. Moving Heaven and Earth: Administrative Search and Selection Processes and the Experience of an African American Woman Senior Administrator

    ERIC Educational Resources Information Center

    Barnett-Johnson, Kim R.

    2009-01-01

    The purpose of this case/phenomenological study was to examine a collegiate administrative search and selection process and the experience of an African American woman who was selected to the position of chancellor. A case concerning the search process of a regional campus of Ivy Tech Community College of Indiana was identified and chosen.…

  18. Sex-Role Egalitarian Attitudes and Gender Role Socialization Experiences of African American Men and Women: A Mixed Methods Paradigm

    ERIC Educational Resources Information Center

    Heard, Courtney Christian Charisse

    2013-01-01

    The purpose of this study was to assess the sex-role egalitarian attitudes and gender role socialization experiences of African American men and women. A sequential mixed-methods design was employed to research this phenomenon. The Sex-Role Egalitarianism Scale-Short Form BB (SRES-BB) was utilized to assess sex-role egalitarian attitudes (King…

  19. Seismic waves from elephant vocalizations: A possible communication mode?

    NASA Astrophysics Data System (ADS)

    Günther, Roland H.; O'Connell-Rodwell, Caitlin E.; Klemperer, Simon L.

    2004-06-01

    We conducted experiments with trained African elephants that show that low-frequency elephant vocalizations produce Rayleigh waves. We model a potential range for these seismic waves, under ideal conditions, of c. 2 km. In appropriate conditions, surface waves from an elephant's infrasonic vocalizations might propagate further than airborne sound and provide advantages over acoustic communication. However, if we use the detection capabilities of the human ear as a benchmark for the signal-detection thresholds of elephants, our estimates of attenuation and ambient seismic noise suggest that the seismic detection range is unlikely to exceed the acoustic detection range under normal atmospheric conditions. We conclude that elephants may benefit from seismic detection in circumstances where the range of acoustic communication is limited, or in cases where multimodal communication is advantageous. Given our current understanding, elephants are unlikely to rely on seismic waves as their primary mode for long-range communication.

  20. Characterization of blocks impacts from seismic signal: insights from laboratory experiments

    NASA Astrophysics Data System (ADS)

    Farin, M.; Mangeney, A.; Toussaint, R.; de Rosny, J.; Sainte-Marie, J.; Shapiro, N.

    2014-12-01

    Rockfalls, debris flows and rock avalanches represent a major natural hazard for the population in mountainous, volcanic and coastal areas but their direct observation on the field is very difficult. Recent field studies showed that gravitational instabilities can be detected, localized and characterized thanks to the seismic signal they generate. Therefore, a burning challenge for risks assessment related to these events is to obtain quantiative informations on the characteristics of the rockfalls (mass, speed, extension,...) from the properties of the signal (seismic energy, frequencies,...). Using a theoretical model of viscoelastic impact of a sphere on a plane, we develop analytical scaling laws relating the energy radiated in elastic waves, the energy dissipated in viscoelasticity during the impact and the frequencies of the generated acoustic signal to the mass m and the impact speed Vz of the sphere and to the elastic parameters of the involved materials. The elastic energy is shown to vary as m5/3Vz11/5 on plates and as mVz13/5 on blocks, regardless of the elastic parameters. The energy dissipated in viscoelasticity does not depend on the support thickness and varies as m2/3Vz11/5. The mean frequency of the generated signal is inversely proportional to the impact duration. Then, we conduct simple laboratory experiments that consist in dropping spherical beads of different size and materials and small gravels on thin plates of glass and Plexiglass and rock blocks. The elastic energy emitted by an impact on the supports is first quantitatively estimated and compared to the potential energy of fall and to the potential energy change during the shock. We observe a quantitative agreement between experimental data and the analytical scaling laws, even when we use small gravels instead of spherical beads as impactors. These experiments allows to valid the theoretical model and to establish the energy budget of an impact. In the experiments, piezoelectric

  1. Seismic results from DOE`s non-proliferation experiment: A comparison of chemical and nuclear explosions

    SciTech Connect

    Denny, M.; Goldstein, P.; Mayeda, K.; Walter, W.

    1995-01-01

    The basic results from the US Department of Energy`s (DOE`s) NonProliferation Experiment (NPE) for seismic signal generation are that the source function for a chemical explosion is equivalent to that of a nuclear explosion of about twice the yield and that the seismic moment measurements are consistent between freefield, local, and regional measurements. In addition, evidence was found that Pn in the Basin and Range province of the western United States is a turning ray and is simply proportional to the source function while the transfer functions for Pg and Lg are low-pass in nature.

  2. The North East Italy (NI) broadband seismic network run by OGS: experience in improving the long period performances

    NASA Astrophysics Data System (ADS)

    Pesaresi, D.

    2009-04-01

    experimented and routinely used by the world wide GEOFON seismic network and the German regional seismic network: examples and performances of a typical OGS installation will be shown.

  3. Transition from slab to slabless: Results from the 1993 Mendocino triple junction seismic experiment

    USGS Publications Warehouse

    Beaudoin, B.C.; Godfrey, N.J.; Klemperer, S.L.; Lendl, C.; Trehu, A.M.; Henstock, T.J.; Levander, A.; Holl, J.E.; Meltzer, A.S.; Luetgert, J.H.; Mooney, W.D.

    1996-01-01

    Three seismic refraction-reflection profiles, part of the Mendocino triple junction seismic experiment, allow us to compare and contrast crust and upper mantle of the North American margin before and after it is modified by passage of the Mendocino triple junction. Upper crustal velocity models reveal an asymmetric Great Valley basin overlying Sierran or ophiolitic rocks at the latitude of Fort Bragg, California, and overlying Sierran or Klamath rocks near Redding, California. In addition, the upper crustal velocity structure indicates that Franciscan rocks underlie the Klamath terrane east of Eureka, California. The Franciscan complex is, on average, laterally homogeneous and is thickest in the triple junction region. North of the triple junction, the Gorda slab can be traced 150 km inboard from the Cascadia subduction zone. South of the triple junction, strong precritical reflections indicate partial melt and/or metamorphic fluids at the base of the crust or in the upper mantle. Breaks in these reflections are correlated with the Maacama and Bartlett Springs faults, suggesting that these faults extend at least to the mantle. We interpret our data to indicate tectonic thickening of the Franciscan complex in response to passage of the Mendocino triple junction and an associated thinning of these rocks south of the triple junction due to assimilation into melt triggered by upwelling asthenosphere. The region of thickened Franciscan complex overlies a zone of increased scattering, intrinsic attenuation, or both, resulting from mechanical mixing of lithologies and/or partial melt beneath the onshore projection of the Mendocino fracture zone. Our data reveal that we have crossed the southern edge of the Gorda slab and that this edge and/or the overlying North American crust may have fragmented because of the change in stress presented by the edge.

  4. Active Source Tomography of Stromboli Volcano (Italy): Results From the 2006 Seismic Experiment.

    NASA Astrophysics Data System (ADS)

    Zuccarello, L.; Patanè, D.; Cocina, O.; Castellano, M.; Sgroi, T.; Favali, P.; de Gori, P.

    2008-12-01

    Stromboli island, located in the Southern Tyrrhenian sea, is the emerged part (about 900 m a.s.l.) of a 3km-high strato-volcano. Its persistent Strombolian activity, documented for over 2000 years, is sometimes interrupted by lava effusions or major explosions. Despite the amount of recent published geophysical studies aimed to clarifying eruption dynamics, the spatial extend and geometrical characteristics of the plumbing system remain poorly understood. In fact, the knowledge of the inner structure and the zones of magma storage is limited to the upper few hundreds meters of the volcanic edifice and P- and S-waves velocity models are available only in restricted areas. In order to obtain a more suitable internal structural and velocity models of the volcano, from 25 November to 2 December 2006, a seismic tomography experiment through active seismics using air-gun sources was carried out and the final Vp model is here presented. The data has been inverted for the Vp structure by using the code Simulps13q, considering a 3D grid of nodes spaced 0.5 km down to 2 km depth, beneath the central part of volcano. The results show a relatively high velocity zones located both in the inner part of the volcanic structure, at about 1km b.s.l. and in the last 200-300 m a.s.l. in correspondence with the volcanic conduit. Slower zones were located around the summit craters in agreement with volcanological and petrological informations for the area. The relatively high velocity zones could suggest the presence of intrusive bodies related to the plumbing system.

  5. Coparenting Experiences in African American Families: An Examination of Single Mothers and their Non-Marital Coparents

    PubMed Central

    Gonzalez, Michelle; Jones, Deborah J.; Parent, Justin

    2015-01-01

    African American youth from single mother homes continue to be overrepresented in statistics on risk behavior and delinquency, a trend that many be attributed to father-absence, socioeconomic disadvantage, and compromises in parenting more typical of single than two-parent families. Yet, this risk-focused perspective ignores a long-standing strength of the African American community, the involvement and potential protective impact of extended family members in childrearing. This study describes the experiences of 95 African American single mothers and their non-marital coparents who participated in a study of African American single mother families with an 11 to 16 year old child. Specifically, the study examines: 1) the extent to which nonmarital coparents are involved in childrearing; 2) the relative levels of risk (i.e., depression, mother-coparent conflict) and protective (i.e., parenting) associated with maternal and coparent involvement; and 3) how similarly and/or differently coparent and mother variables operate with regard to youth externalizing problems. Findings reveal that a range of family members and other adults actively participate in childrearing in African American single mother families, coparents do not differ from mothers on certain study variables (i.e., depression and mother-coparent conflict) but do for others (parenting), and coparent involvement is associated with youth adjustment in ways that are similar to our more established understanding of maternal involvement. The potential clinical implications of the findings are discussed and future research directions are highlighted. PMID:24479612

  6. Regional Seismic Signals from Chemical Explosions, Nuclear Explosions and Earthquakes: Results from the Arizona Source Phenomenology Experiment

    SciTech Connect

    Walter, W R; Gok, R; Mayeda, K; Sicherman, A; Bonner, J; Leidig, M

    2005-09-02

    Routine industrial mining explosions play two important roles in seismic nuclear monitoring research: (1) they are a source of background events that need to be discriminated from potential nuclear explosions; (2) as some of the only explosions occurring in the current de facto global moratoria on nuclear testing, their signals should be exploited to improve the calibration of seismic m monitoring systems. A common issue monitoring arising in both of these roles is our limited physical understanding of the causes behind observed differences and similarities in the seismic signals produced by routine industrial mining blasts and small underground nuclear tests. In 2003 a consortium (Weston, SMU, LLNL, LANL and UTEP) carried out a Source Phenomenology Experiment (SPE), a series of dedicated explosions designed to improve this physical understanding, particularly as it relates to seismic methods of discriminating between signals from three different source types: earthquakes, industrial blasts, and nuclear tests. Here we very briefly review prior field experimental work that examined the seismic relationships between these source types.

  7. The effect of deformation history on the interpretation of seismic anisotropy in the upper mantle: experiments and numerical modeling

    NASA Astrophysics Data System (ADS)

    Boneh, Y.; Skemer, P. A.; Morales, L. F. G.; Kaminski, E. C.

    2015-12-01

    The main source of seismic anisotropy in the upper mantle is the deformation-induced crystallographic preferred orientation (CPO) of olivine. The interpretation of seismic anisotropy relies on models and experiments that predict certain relationships between olivine CPO and the deformation kinematics. Under some conditions, such as the interiors of oceanic plates, these relationships may be quite simple. However, near plate boundaries flow patterns are complex and the interpretation of seismic anisotropy is not straight-forward. In this contribution we describe the effect of deformation history on the re-orientation of olivine CPO as a function of strain. High pressure and temperature deformation experiments were performed on the Åheim dunite, which exhibits a pre-existing texture. Experiments were conducted in three different configurations with the pre-existing foliation at 0°, 45°, and 90° to the axis of compression, simulating three unique deformation histories. Deformation microstructures and texture are analyzed using electron backscatter diffraction (EBSD). The experiments show that up to strains of ~0.7 the three configurations evolve differently from one another, and from models initiated with random textures. Moreover, none of the models achieved the expected textural steady-state. The experiments results are then compared to numerical simulations using a Viscoplastic Self Consistent (VPSC) approach, and D-Rex. The input for the models is the Åheim dunite CPO in the three configurations used in the experiments. It is shown that, generally, texture symmetry evolves similarly in the models and the experiments although there are notable differences in texture strength. To achieve better agreement between experiments and models, new model parameterizations are proposed. Finally, we use the new parameterization of D-Rex to simulate a range of plausible deformation histories and associated seismic anisotropy in a variety of flow settings.

  8. Experience of Consolidation Of Disused Sources In Developing Countries, An African Perspective

    SciTech Connect

    Kifanga, L.D.; Mompome, W.K.; Shao, D.

    2008-07-01

    Application of sealed sources in agriculture, medicine and industry was used in many African countries without having any arrangements in place for managing the sources when their useful life was over. In Tanzania a substantial use of such sources was utilized. In the early days source management was not an area that was given the required attention hence a legacy associated with sealed sources became evident in many African countries and Tanzania was one of them. In the 90's Tanzania Atomic Energy Commission (TAEC), realized the scope of the waste problem and began to participate in an International Atomic Energy Agency Regional (IAEA) project on waste management. Tanzania in cooperation with IAEA initiated activities under the IAEA Technical Cooperation and the Regional projects 'Strengthening Waste Management Infrastructure, RAF/4/015'; and 'Sustaining the Waste Management Infrastructure RAF/3/005' which played a significant role. The first outcome of the project was realized in 1999, as the first 'Temporary Radioactive Waste Storage Facility' began to operate. This particular Storage facility gave the first impact as well as the need to develop this particular infrastructure further. As the project carried on, more and more orphan sources were recovered, collected and safely stored at the facility. As the use of nuclear technology was expanding and the identification of the extent of sealed sources in the countries became more defined, the need to develop a 'Central Radioactive Waste Management Facility' (CRWMF) was becoming more desired. The central radioactive waste storage facility was constructed and commissioned in 2005. The facility was more advanced and could be used for much longer periods of time, as one of the most advanced storage facility in the Region. At present a large number of disused sources from various industries as well as from different activities are being stored at the facility. Tanzanian authorities are also planning to initiate a

  9. Evaluation and developmental studies of possible active seismic experiments during the post-Apollo period

    NASA Technical Reports Server (NTRS)

    Kovach, R. L.

    1974-01-01

    Seismic velocity studies pertinent to the lunar crust and mantle are briefly summarized. The compressional and shear wave velocities in loose aggregates are discussed along with the effects of temperature on seismic velocity in compacted powders. Abstracts of papers concerning the lunar structure are included.

  10. The Seismic Aftershock Monitoring System (SAMS) for OSI - Experiences from IFE14

    NASA Astrophysics Data System (ADS)

    Gestermann, Nicolai; Sick, Benjamin; Häge, Martin; Blake, Thomas; Labak, Peter; Joswig, Manfred

    2016-04-01

    An on-site inspection (OSI) is the third of four elements of the verification regime of the Comprehensive Nuclear-Test-Ban Treaty (CTBT). The sole purpose of an OSI is to confirm whether a nuclear weapon test explosion or any other nuclear explosion has been carried out in violation of the treaty and to gather any facts which might assist in identifying any possible violator. It thus constitutes the final verification measure under the CTBT if all other available measures are not able to confirm the nature of a suspicious event. The Provisional Technical Secretariat (PTS) carried out the Integrated Field Exercise 2014 (IFE14) in the Dead Sea Area of Jordan from 3 November to 9. December 2014. It was a fictitious OSI whose aim was to test the inspection capabilities in an integrated manner. The technologies allowed during an OSI are listed in the Treaty. The aim of the Seismic Aftershock Monitoring System (SAMS) is to detect and localize aftershocks of low magnitudes of the triggering event or collapses of underground cavities. The locations of these events are expected in the vicinity of a possible previous explosion and help to narrow down the search area within an inspection area (IA) of an OSI. The success of SAMS depends on the main elements, hardware, software, deployment strategy, the search logic and not least the effective use of personnel. All elements of SAMS were tested and improved during the Built-Up Exercises (BUE) which took place in Austria and Hungary. IFE14 provided more realistic climatic and hazardous terrain conditions with limited resources. Significant variations in topography of the IA of IFE14 in the mountainous Dead Sea Area of Jordan led to considerable challenges which were not expected from experiences encountered during BUE. The SAMS uses mini arrays with an aperture of about 100 meters and with a total of 4 elements. The station network deployed during IFE14 and results of the data analysis will be presented. Possible aftershocks of

  11. Siting of USArray Seismic Stations in North Carolina and southern Virginia: Experience of NC-1 Team

    NASA Astrophysics Data System (ADS)

    Martin, P.; Howard, J.; Horne, T.

    2012-12-01

    The USArray component of the EarthScope, a transportable array of 400 seismometers installed in a grid about 70 km apart, is in the next two years entering its final stage with station deployment along the Atlantic coast of the United States. Here, we present the experience of the student-faculty team from North Carolina Central University (NCCU) in finding and documenting the suitable sites for the twenty five USArray stations in North Carolina and southern Virginia. The ideal sites are easily accessible yet far from traffic and other sources of noise, with good cell phone coverage, sun exposure and out of flood-prone areas. Although the initial selection of potential locations was done using geospatial mapping and analysis software provided by EarthScope, finding and finalizing the sites involved driving more then 1,000 miles each week for over two months inspecting possible site locations. Aside from driving, the majority of time was spent talking about the EarthScope project and hosting of USArray stations to mostly reluctant landowners. In addition to facing various challenges in finding appropriate sites due to land use issues, such as suburban sprawl of central North Carolina, or topography factors, such as low lying flood prone coastal areas, by far the major challenge was finding the landowners willing to host the seismic station for the necessary three years. In addition to involving students from an HBCU in seismology related project and increasing the visibility of NCCU geophysics program in the University and local community through publicity releases in local media and on university web site, the project had an important outreach component. As North Carolina is located along the seismically quiet, passive Atlantic margin, most residents are not familiar with earthquakes and seismology and the siting experience provided students an opportunity to practice explaining the earthquake research to the general public. The dialog also highlighted science

  12. When Aspiration Meets Opportunity: Examining Transitional Experiences of African American Males in College Readiness Programs

    ERIC Educational Resources Information Center

    Baber, Lorenzo DuBois

    2014-01-01

    The lack of postsecondary success for African American males has garnered significant attention from academic scholars and public policy leaders. While this scholarship provides a strong portrait on issues related to African American males, there are still significant gaps to be addressed. Most notably, current research tends to focus on students…

  13. Gender and Racial Experiences in Executive School Leadership: Perceptions of African American Female Superintendents

    ERIC Educational Resources Information Center

    Colbert, Daveda Jean

    2009-01-01

    There is a leadership crisis that exists in our schools creating an urgent need for effective leadership. Even though African American women have made slight gains, throughout the country people of color and women are dramatically underrepresented in the superintendency. Therefore, the primary purpose of this study is to provide African American…

  14. Health Behaviors and Breast Cancer: Experiences of Urban African American Women

    ERIC Educational Resources Information Center

    Stolley, Melinda R.; Sharp, Lisa K.; Wells, Anita M.; Simon, Nolanna; Schiffer, Linda

    2006-01-01

    Breast-cancer survival rates are lower among African American women compared to White women. Obesity may contribute to this disparity. More than 77% of African American women are overweight or obese. Adopting health behaviors that promote a healthy weight status may be beneficial because obesity increases risk for recurrence. Studies among White…

  15. Faculty Perceptions of, and Experiences with, African American Male Students at a Community College

    ERIC Educational Resources Information Center

    Jenkins, Shantelle K.

    2013-01-01

    Many studies involving African American male students have focused on achievement gaps and student retention models of those attending four-year institutions. However, there are limited investigations of African American male students at the community college and very few that focus on faculty perceptions. This study employed a mixed Delphi…

  16. Jumping through Hoops: College Choice Experiences of African American Male Community College Club Basketball Players

    ERIC Educational Resources Information Center

    Ellis, Kimberly Carlotta

    2011-01-01

    This study aimed to learn what factors influenced the college choice decision-making process of African American male club basketball players in the community college. To understand how the participants determined their educational path, face-to-face interviews were conducted with 21 African American male students who were enrolled in at least six…

  17. Teaching White Students Black History: The African-American Experience in the Classroom

    ERIC Educational Resources Information Center

    Burrell, Leon F.; Walsh, Robert L.

    2001-01-01

    Many white students are barely exposed to African-American history throughout their schooling. When students do examine the other side of American history, the one not generally found in their textbooks, they often wonder why they have not learned this before. An understanding of African-American history is central to any effort to eliminate…

  18. Leading the Way: Inside the Experiences of High-Achieving African-American Male Students

    ERIC Educational Resources Information Center

    Harper, Shaun R.

    2005-01-01

    More than two-thirds of all African American males who begin college never finish. This and a legion of other discouraging facts about African American males are the usual headlines. Sharon Fries-Britt suggests that "the disproportionate focus on Black underachievement in the literature not only distorts the image of the community of Black…

  19. Reflections on Academic Development: What We Can Learn from the South African Experience. Technical Report.

    ERIC Educational Resources Information Center

    Epstein, Ruth

    A study examined academic literacy in high-risk South African students entering postsecondary education, and the relationship of academic literacy to instructional development. Data were gathered in discussions with academic staff at South African universities and technikons and at the University of Saskatchewan. The report begins with background…

  20. African-American Materials Project Experiment in Regional Cooperation. Final Report.

    ERIC Educational Resources Information Center

    Hall, Carol J.

    The African-American Materials Project was a three year venture in bibliographic control of African-American materials. It was a regional project, designed to locate and describe materials in six Southern states. The project was divided into three periods. Phase I was devoted to locating existing collections through the use of a questionnaire,…

  1. Application of a cross correlation-based picking algorithm to an active seismic experiment in Sicily and Aeolian Islands

    NASA Astrophysics Data System (ADS)

    Diaz, Alejandro; Álvarez, Isaac; De la Torre, Ángel; García, Luz; Benítez, Ma Carmen; Cortés, Guillermo

    2014-05-01

    The detection of the arrival time of seismic waves or picking is of great importance in many seismology applications. Traditionally, picking has been carried out by human operators. This process is not systematic and relies completely on the expertise and judgment of the analysts. The limitations of manual picking and the increasing amount of data daily stored in the seismic networks worldwide distributed and in active seismic experiments lead to the development of automatic picking algorithms. Current conventional algorithms work with single signals, such as the "short-term average over long-term average" (STA/LTA) algorithm, autoregressive methods or the recently developed "Adaptive Multiband Picking Algorithm" (AMPA). This work proposes a correlation-based picking algorithm, whose main advantage is the fact of using the information of a set of signals, improving the signal to noise ratio and therefore the picking accuracy. The main advantage of this approach is that the algorithm does not require to set up sophisticated parameters, in contrast to other automatic algorithms. The accuracy of the conventional STA/LTA algorithm, the recently developed AMPA algorithm, an autoregressive method, and a preliminary version of the cross correlation-based picking algorithm were assessed using a huge data set composed by active seismic signals from experiments in Tenerife Island (January 2007, Spain). The experiment consisted of the deployment of a dense seismic network on Tenerife Island (125 seismometers in total) and the shooting of air-guns around the island with the Spanish oceanographic vessel Hespérides (6459 air shots in total). Only 110937 signals (13.74% of the total) had the signal to noise ratio enough to be manually picked. Results showed that the use of the cross correlation-based picking algorithm significantly increases the number of signals that can be considered in the tomography. A new active seismic experiment will cover Sicily and Aeolian Islands (TOMO

  2. Lesser Antilles Subduction Zone Investigation by a Cluster of Large Seismic Experiments in the Forearc Region

    NASA Astrophysics Data System (ADS)

    Last, T.

    2007-12-01

    subduction mega-thrust fault plane, and which is here the main target has been localized along 3 transects to the Arc thanks to a preliminary survey in 2001, the French SISMANTILLES cuise. We will present the first results obtained during these experiments dedicated specifically to image at depth the seismic structure and activity of this region. To image faults at depth and the detailed upper-crustal structure, 3700 km of multi-beam bathymetry and multi-channel reflection seismic profiles have been collected along a grid comprising 7 strike-lines of up to 300 km long and spaced by 15 km and 12 transects of up to 150 km long and spaced by 25 km (SISMANTILLES 2). All these airgun shots dedicated to deep penetration have been recorded by the 84 OBSs and 20 OBHs deployed by the F/S Merian and N/O Atalante on the nodes of this grid of profiles. It will permit to get Vp constraints on the deep forearc region and mantle wedge by wide-angle refraction studies, as well as constraints on the updip and downdip limits of the seismogenic part of the mega-thrust fault plane. Two of these transects have been extended across the whole arc during the TRAIL survey, with up to 50 OBSs deployed along both 240 km long profiles. All these OBSs remained several months beyond the shot experiments for local earthquakes Vp and Vp/Vs tomography. They have been recovered and partly redeployed by N/O Antea during the OBSANTILLES survey. A significant number of those instruments had broadband seismometers, a notable originality in the case of the OBSs to detect low-frequency transient signals.

  3. Investigating the lithospheric structure of Queen Maud Land, East-Antarctica: a year-round seismic experiment

    NASA Astrophysics Data System (ADS)

    Lombardi, Denis; Camelbeeck, Thierry; Rapagnani, Giovanni

    2014-05-01

    The recently launched LISSA project is dedicated to imaging the lithospheric structure of East-Antarctica in relation with the past geodynamics of Gondwana by probing the Sør Rondane Mountains, Queen Maud Land, a belt formed from various metamorphosed terranes mobilized during the Proterozoic Pan-African orogeny. The project benefits from the establishment in 2009 of the Belgian Princess Elisabeth base built at the northern tip of the mountain chain. Our aim is to investigate the deep lithospheric structure of the region by setting up in January 2014 6 broadband seismic stations along a 100 km long North-South profile through the mountain belt striking perpendicular to the various geological terranes. All stations are set up to be year-round autonomously powered, all but one being on rock outcrops and only one being remotely accessible. We describe the technical developpment for year-round operation and the installation site conditions. Then we present the first collected data by analyzing the background seismic noise providing data quality and finally we provide a first inventory of a 1 month event dataset.

  4. Conceptual Design and Architecture of Mars Exploration Rover (MER) for Seismic Experiments Over Martian Surfaces

    NASA Astrophysics Data System (ADS)

    Garg, Akshay; Singh, Amit

    2012-07-01

    Keywords: MER, Mars, Rover, Seismometer Mars has been a subject of human interest for exploration missions for quite some time now. Both rover as well as orbiter missions have been employed to suit mission objectives. Rovers have been preferentially deployed for close range reconnaissance and detailed experimentation with highest accuracy. However, it is essential to strike a balance between the chosen science objectives and the rover operations as a whole. The objective of this proposed mechanism is to design a vehicle (MER) to carry out seismic studies over Martian surface. The conceptual design consists of three units i.e. Mother Rover as a Surrogate (Carrier) and Baby Rovers (two) as seeders for several MEMS-based accelerometer / seismometer units (Nodes). Mother Rover can carry these Baby Rovers, having individual power supply with solar cells and with individual data transmission capabilities, to suitable sites such as Chasma associated with Valles Marineris, Craters or Sand Dunes. Mother rover deploys these rovers in two opposite direction and these rovers follow a triangulation pattern to study shock waves generated through firing tungsten carbide shells into the ground. Till the time of active experiments Mother Rover would act as a guiding unit to control spatial spread of detection instruments. After active shock experimentation, the babies can still act as passive seismometer units to study and record passive shocks from thermal quakes, impact cratering & landslides. Further other experiments / payloads (XPS / GAP / APXS) can also be carried by Mother Rover. Secondary power system consisting of batteries can also be utilized for carrying out further experiments over shallow valley surfaces. The whole arrangement is conceptually expected to increase the accuracy of measurements (through concurrent readings) and prolong life cycle of overall experimentation. The proposed rover can be customised according to the associated scientific objectives and further

  5. "Ain't Nobody Gonna Get Me down": An Examination of the Educational Experiences of Four African American Women Labeled with Disabilities

    ERIC Educational Resources Information Center

    Petersen, Amy J.

    2009-01-01

    This study used qualitative research methods to explore the educational experiences of four African American women with disabilities, revealing how each participant developed a critical consciousness in response to the dominant ideology surrounding the discourses of African American, woman, and disabled. The development of a critical consciousness…

  6. Exploring How African American Males from an Urban Community Navigate the Interracial and Intra-Racial Dimensions of Their Experiences at an Urban Jesuit High School

    ERIC Educational Resources Information Center

    Simmons, Robert W., III

    2012-01-01

    African American males from urban communities have been attending Jesuit high schools in urban spaces for many years, yet little to no literature exists that explores their experiences while attending these elite private schools. This qualitative study of 10 African American males from an urban community attending a similarly positioned Jesuit…

  7. A Hermeneutic Phenomenological Study of the Experiences of Female African American Undergraduate Engineering Students at a Predominantly White and an Historically Black Institution

    ERIC Educational Resources Information Center

    Frillman, Sharron Ann

    2011-01-01

    This phenomenological study examined the experiences of twelve female African Americans enrolled as fulltime undergraduate engineering students at North Carolina Agricultural and Technical State University, an historically Black university, and seven female African Americans enrolled as undergraduate engineering students at Purdue University in…

  8. Navigating Race and Cultural Identity: A Phenomenological Study of the Lived Experiences of African American Secondary Principals on the U.S.-Mexico Border of El Paso, Texas

    ERIC Educational Resources Information Center

    Hill, Natashia J.

    2013-01-01

    Presently the paucity of scholarship available is often unitary in nature and usually focuses on the lived experiences of African Americans principals in a predominately African American urban context and as well as emphasizes the necessity of same race principals for the purpose of mentorship and racial representation. Race and cultural identity…

  9. Negotiating Identity in a Bubble: A Critical Race Analysis of African American High School Students' Experiences in an Elite, Independent School

    ERIC Educational Resources Information Center

    DeCuir-Gunby, Jessica T.

    2007-01-01

    This study used critical race theory to examine how African American adolescents negotiated race and class identity at Wells Academy, a predominately white, independent school. Interviews were conducted, exploring the experiences of six African American high school students. Their counterstories were analyzed focusing on the critique of…

  10. Experimenting in Distance Education: The African Virtual University (AVU) and the Paradox of the World Bank in Kenya--A Rejoinder

    ERIC Educational Resources Information Center

    Munene, Ishmael I.

    2007-01-01

    This rejoinder is in response to criticism against the African Virtual University (AVU), an internet-based education modality, by Amutabi and Oketch [2003. Experimenting in distance education: the African Virtual University (AVU) and the Paradox of World Bank in Kenya. International Journal of Educational Development 23, 57-73]. By closely…

  11. A New Generation of Large Seismic Refraction Experiments in Central Europe (1997-2003)

    NASA Astrophysics Data System (ADS)

    Guterch, A.; Grad, M.; Spicak, A.; Brueckl, E.; Hegedus, E.; Keller, G. R.; Thybo, H.

    2003-12-01

    Beginning in 1997, Central Europe has been covered by an unprecedented network of seismic refraction experiments. These experiments (POLONAISE'97, CELEBRATION 2000, ALP 2002, SUDETES 2003) have only been possible due a massive international cooperative effort. The total length of all profiles is about 19,000 km, and over 300 explosive sources were employed. The result is a network of seismic refraction profiles that extends along the Trans-European Suture Zone region of Poland and the Bohemian massif, Pannonian basin, trough the Carpathians and Alps to the Adriatic Sea and the Dinarides. As reflected in structures within these areas, Central Europe has experienced a complex tectonic history that includes the Caledonian, Variscan, and Alpine orogenies. The related TESZ region is a broad zone of deformation that extends across Europe from British Isles to the Black Sea region that formed as Europe was assembled from a complex collage of terranes during the late Palaeozoic. For example, the Bohemian massif is mostly located in the Czech Republic and is a large, complex terrane whose origin can be traced to northern Gondwana (Africa). These terranes were accreted along the margin of Baltica that was formed during the break-up of Rodinia. The tectonic evolution of this region shares many attributes with the Appalachian/Ouachita origin and is certainly of global important to studies in terrane tectonics and continental evolution. In southern Poland, several structural blocks are located adjacent to Baltica and were probably transported laterally along it similar to the Cenozoic movement of terranes along the western margin of North America. The younger Carpathian arc and Pannonian back-arc basin were also targeted by these experiments. Thickness of the crust in the area of investigations changes from 22-25 km in the Pannonian basin to about 55 km in the Trans-European Suture Zone in SE Poland. Together, these experiments are providing an unprecedented 3-D image of the

  12. Seismic aftershock monitoring for on-site inspection purposes. Experience from Integrated Field Exercise 2008.

    NASA Astrophysics Data System (ADS)

    Labak, P.; Arndt, R.; Villagran, M.

    2009-04-01

    One of the sub-goals of the Integrated Field Experiment in 2008 (IFE08) in Kazakhstan was testing the prototype elements of the Seismic aftershock monitoring system (SAMS) for on-site inspection purposes. The task of the SAMS is to collect the facts, which should help to clarify nature of the triggering event. Therefore the SAMS has to be capable to detect and identify events as small as magnitude -2 in the inspection area size up to 1000 km2. Equipment for 30 mini-arrays and 10 3-component stations represented the field equipment of the SAMS. Each mini-array consisted of a central 3-component seismometer and 3 vertical seismometers at the distance about 100 m from the central seismometer. The mini-arrays covered approximately 80% of surrogate inspection area (IA) on the territory of former Semipalatinsk test site. Most of the stations were installed during the first four days of field operations by the seismic sub-team, which consisted of 10 seismologists. SAMS data center comprised 2 IBM Blade centers and 8 working places for data archiving, detection list production and event analysis. A prototype of SAMS software was tested. Average daily amount of collected raw data was 15-30 GB and increased according to the amount of stations entering operation. Routine manual data screening and data analyses were performed by 2-6 subteam members. Automatic screening was used for selected time intervals. Screening was performed using the Sonoview program in frequency domain and using the Geotool and Hypolines programs for screening in time domain. The screening results were merged into the master event list. The master event list served as a basis of detailed analysis of unclear events and events identified to be potentially in the IA. Detailed analysis of events to be potentially in the IA was performed by the Hypoline and Geotool programs. In addition, the Hyposimplex and Hypocenter programs were also used for localization of events. The results of analysis were integrated

  13. Site Characterization of the Source Physics Experiment Phase II Location Using Seismic Reflection Data

    NASA Astrophysics Data System (ADS)

    Sexton, E. A.; Snelson, C. M.; Chipman, V.; Emer, D. F.; White, R. L.; Emmitt, R.; Wright, A. A.; Drellack, S.; Huckins-Gang, H.; Mercadante, J.; Floyd, M.; McGowin, C.; Cothrun, C.; Bonal, N.

    2013-12-01

    An objective of the Source Physics Experiment (SPE) is to identify low-yield nuclear explosions from a regional distance. Low-yield nuclear explosions can often be difficult to discriminate among the clutter of natural and man-made explosive events (e.g., earthquakes and mine blasts). The SPE is broken into three phases. Phase I has provided the first of the physics-based data to test the empirical models that have been used to discriminate nuclear events. The Phase I series of tests were placed within a highly fractured granite body. The evolution of the project has led to development of Phase II, to be placed within the opposite end member of geology, an alluvium environment, thereby increasing the database of waveforms to build upon in the discrimination models. Both the granite and alluvium sites have hosted nearby nuclear tests, which provide comparisons for the chemical test data. Phase III of the SPE is yet to be determined. For Phase II of the experiment, characterization of the location is required to develop the geologic/geophysical models for the execution of the experiment. Criteria for the location are alluvium thickness of approximately 170 m and a water table below 170 m; minimal fracturing would be ideal. A P-wave mini-vibroseis survey was conducted at a potential site in alluvium to map out the subsurface geology. The seismic reflection profile consisted of 168 geophone stations, spaced 5 m apart. The mini-vibe was a 7,000-lb peak-force source, starting 57.5 m off the north end of the profile and ending 57.5 m past the southern-most geophone. The length of the profile was 835 m. The source points were placed every 5 m, equally spaced between geophones to reduce clipping. The vibroseis sweep was from 20 Hz down to 180 Hz over 8 seconds, and four sweeps were stacked at each shot location. The shot gathers show high signal-to-noise ratios with clear first arrivals across the entire spread and the suggestion of some shallow reflectors. The data were

  14. Transient Creep Events and the Transition from Aseismic to Seismic Faulting Observed in Laboratory Experiments

    NASA Astrophysics Data System (ADS)

    Schubnel, A.; Brantut, N.; Fortin, J.; Gueguen, Y.

    2008-12-01

    Dry triaxial compression experiments performed on Carrara marble and Volterra Gypsum at confining pressures ranging from 10 to 100MPa revealed an important dependence of the strain rate on the confining stress. At constant shear stress, transient exponential increases in axial strain, similar to transient creep events observed on the field, were observed for small decreases of the confining pressure (1-10MPa), which could eventually lead to ductile failure nucleation. In such case, rupture propagation was silent and slow (several hundreds of seconds), although accompanied by stress drops of the order of several tens of MPas and millimetric slips. However, as the slip velocity increased during failure propagation, continuous acoustic waveform recordings enabled us to illustrate the transition from aseismic to seismic faulting. These experiments provide a clear experimental case of silent, slow localized failure in rocks as a result of an interplay between intragranular plasticity and microcracking. In the case of ductile failure as in the marble, dislocation and twin accumulation is such that cracks propagation steps are small and/or slow, and thus the radiated energy release rate remains small at early stages of rupture and increases with rupture speed. This last observation clearly highlights the dependence of radiated acoustic (and microseismic?) energy during crack propagation not only on the rupture propagation speed and the slip velocity but most importantly on the rock's lithology and rheology. This could have important implications as carbonates are prevalent within sedimentary basins. At even at shallower depths and prevalent within fault gouges, clay minerals are also expected to behave in a similar way.

  15. Comparison of seismic and hydrodynamic yield determinations for the Soviet joint verification experiment of 1988

    PubMed Central

    Sykes, Lynn R.; Ekström, Göran

    1989-01-01

    Seismic magnitudes determined from surface and body waves for the Soviet underground nuclear explosion of September 14, 1988, are used to calculate the yield of that event from previously derived calibration curves. The yield obtained by combining the two seismic estimates is 113 kilotons, which is very close to those obtained by hydrodynamic measurements made on-site. This comparison substantiates previous conclusions about the sizes of past Soviet weapons tests and compliance with the Threshold Test Ban Treaty. The factor of uncertainty in the combined seismic yield is 1.28 at the 68% and 1.62 at the 95% confidence levels, demonstrating that accuracies considerably better than a factor of 2 can be obtained by combining seismic determinations of yield. PMID:16594040

  16. Experiments on the Brazil-nut effect due to seismic shakings

    NASA Astrophysics Data System (ADS)

    Maciel, A.; Tancredi, G.; Lluch, N.

    2014-07-01

    Size segregation processes have been identified as relevant when studying the behaviour of rocks and boulders on the surface and in the interior of a rubble-pile asteroid. The size segregation as a consequence of repeated shakings is also known as the Brazil-nut effect (BNE). These processes might be really important when studying rubble-pile -type asteroids, which may have suffered seisms as a consequence of repeated collisions; such as in the case of asteroid Itokawa. Size segregation processes can be studied using laboratory experiments as well as computational models, the first case being the one initially considered in this work. Previous studies of the BNE were performed using a sinusoidal vertical or horizontal vibration of the containers. Since we are interested in the effects of repeated seismic shakes, we have used in our experiments a sequence of repeated knocks of the container. We built a resin and polycarbonate box, which is filled with marbles of different sizes. Vacuum up to 0.5 % of ambient pressure is established inside the box. The box is subjected to repeated free-falls from heights up to 1m, with impact velocities on the ground up to 4m/s. We have chosen these low velocities since they are comparable to the escape velocities of km-size asteroids; and they are on the order of the displacement velocities of surface material as a consequence of a small impact (far from the impact point; Tancredi et al. 2012). We study the dependence of size segregation processes with the size rate among the spheres and the impact speed of the box. We observe that, when effectively occurs, size segregation mostly depends on the size rate of the particles and very little on the impact speed, even though this slight dependence has been recorded in our experiments. The laboratory experiments have been also numerically simulated using the Discrete Element Method (DEM) package known as ESyS-particle. The results of the numerical simulations are compared to the

  17. Seismic passive: an experiment for the campus of the National University of Colombia

    NASA Astrophysics Data System (ADS)

    Mateus Reyes, S. E.

    2015-12-01

    The generation of seismic image, in areas where the use of active sources it is restricted (like dynamite) or just the area where the area is an active source, it is possible to do it with passive seismic, using seismic interferometry, retrieving the impulse response (Function Green) from the cross-correlation of the ambient noise. It was cross-correlated ambient seismic noise, of a recording made along a line lying on the university campus in Bogota, on that line were located the virtual-source and the traces. For processing, the surface waves were removed and subsequently, it was applied energy normalization to each of the noise panel and were correlated each noise panels with the trace at the chosen virtual-source position. When it was retrieved common-source gathers it was made a new stacking. And with this stack, seismic image was generated. The image obtained was compared with the geological surveys of the area and found that the reflectors match, showing 2 matching reflections. It was determined from this study of seismic exploration on one line, using retrieved reflection data it posible to obtain a migrated reflection imageof the subsurface.

  18. High-resolution shallow-seismic experiments in sand. Part 1: Water table, fluid flow, and saturation

    SciTech Connect

    Bachrach, R.; Nur, A.

    1998-07-01

    A high-resolution, very shallow seismic reflection and refraction experiment was conducted to investigate the seismic response of groundwater level changes in beach sand in situ. A fixed 10-m-long receiver array was used for repeated seismic profiling. Direct measurements of water level in a monitoring well and moisture content in the sand were taken as well. The water table in the well changed by about 1 m in slightly delayed response to the nearby ocean tides. In contrast, inversion of the seismic data yielded a totally different picture. The reflection from the water table at high tide appeared at a later time than the reflection at low tide. This unexpected discrepancy can be reconciled using Gassmann`s equation: a low-velocity layer must exist between the near-surface dry sand and the deeper and much faster fully saturated sand. This low-velocity layer coincides with the newly saturated zone and is caused by a combination of the sand`s high density (close to that of fully saturated sand), and its high compressibility (close to that of dry sand). This low-velocity zone causes a velocity pull-down for the high-frequency reflections, and causes a high-tide reflection to appear later in time than low-tide reflection. The calculated velocities in the dry layer show changes with time that correlate with sand dryness, as predicted by the temporal changes of the sand`s density due to changing water/air ratio. The results show that near-surface velocities in sand are sensitive to partial saturation in the transition zone between dry and saturated sand. The authors were able to extract the saturation of the first layer and the depth to the water table from the seismic velocities.

  19. Seismic Interferometry and the Spatial Auto-Correlation Method on the Regional Coda of the Non-Proliferation Experiment

    NASA Astrophysics Data System (ADS)

    de Ridder, S.; Prieto, G. A.

    2008-12-01

    A seismic recording of the non-proliferation experiment (NPE), made by a petroleum-exploration company in Railroad Valley (Nevada), contains the first break of the regional P phases followed by a three minute long coda. The transverse orientation and sign-bit recording of the array, renders distinguishing phase arrival times difficult. This motivates the use of seismic interferometry. The geometry does not permit recovering the Green's function from the first break arrival times using the stationary phase theorem, however the coda contains sufficiently equipartitioned energy. We study the result of seismic interferometry in the frequency-domain. This procedure is analogous to the spatial auto-correlation (SPAC) method, devised for studying microtremors by Aki in 1957. Cross-correlating two receiver stations retrieves, under favorable circumstances, an approximation of the Green's function between these two stations. To first order, this Green's function consists of a direct event traveling between the receivers. In the frequency domain, the lowest mode in the Green's function is a weighted and scaled zero-order Bessel function of the first kind, J0. We fit the frequency-domain of the recovered Green's functions to damped J0 functions. to recover phase velocity and estimates of the attenuation coefficients. Only energy between 1-4 Hz can be fitted unambiguously with J0 functions, because higher frequencies contain too much spurious energy. This result shows the equivalence of the SPAC method and seismic interferometry for the lowest mode in the Green's function. This study also shows how the coda of a regional event, seemingly unfavorably positioned, can contains energy useful for seismic interferometry.

  20. An overview on geophysical structures in the Eastern Alps revealed by recent seismic experiments

    NASA Astrophysics Data System (ADS)

    Behm, M.; Brueckl, E. P.; Grad, M.

    2009-12-01

    CELEBRATION 2000 and ALP 2002 were two large seismic wide-angle experiments which targeted the lithospheric structure of Central Europe. This presentation highlights crustal features of the Eastern Alps and their transition into adjacent tectonic provinces (Bohemian Massif, Carpathians, Pannonian Basin, Southern Alps and Dinarides) which were unknown prior to these experiments. The Eastern Alps result from the collision of the European platform with the Adriatic plate which got initiated in the Eocene. From the late Oligocene on, escape tectonics towards the unconstrained eastern margin contributed to the evolution of the Eastern Alps. Both processes left their imprints on the surface geology which differs significantly from the Western Alps. Considering the layout of the experiments, an innovative 3D processing scheme was implemented and supplemented by traditional 2D interpretation techniques. The 3D approach provides robust models with large spatial coverage, while the evaluation of 2D profiles allows resolving details at locations of particular interest. The P-wave velocity distribution of crust shows a clear separation into a low-velocity European plate and a high-velocity Adriatic plate. Crustal velocities below the Pannonian Basin are moderate to low. Velocity structures in the uppermost crust correlate well with surface geology and tectonic divisions. One of the most important results is a new map of the Moho discontinuity. Its depth varies between 52 and 24 km, and from its structure we deduce the new crustal fragment Pannonia. Pannonia has shallow crust and is underthrusted by both the European Moho in the North and the Adriatic Moho in the South-West. Although solely vertical component receivers were used, strong S-waves can be observed on some seismograms. Their evaluation confirms the separation into three crustal fragments and provides constraints on Poisson’s ratio. A subhorizontal mantle reflector in a depth range from approximately 55 km is found

  1. Factors linking childhood experiences to adult romantic relationships among African Americans.

    PubMed

    Simons, Leslie Gordon; Simons, Ronald L; Landor, Antoinette M; Bryant, Chalandra M; Beach, Steven R H

    2014-06-01

    It is well known that a high-quality relationship with a romantic partner is related to a variety of positive outcomes associated with health and well-being. Establishing such relationships is an important developmental task for young adults, and past research indicates that there is a link between experiences in the family of origin and the success of later intimate relationships. It has been suggested that this association can be explained by the acquisition of social competencies (e.g., emotions, schemas, traits) that are acquired during childhood in the family of origin and, in turn, influence interaction with adult romantic partners. The current study builds on this foundation by identifying particular competencies expected to explain the association between childhood exposure to supportive and harsh parenting and later patterns of interaction with romantic partners. Specifically, we examine anger management, attachment style, hostile attribution bias, and self-control as potential mediators using prospective, longitudinal data from a sample of 345 African American young adults. Results from structural equation modeling indicate that each of the mediators in our study accounts for a significant portion of the effect of parenting on the quality of adult romantic relationships, although the constructs linking parenting to warm interactions with romantic partners are somewhat different from those that link parenting to hostile interactions with romantic partners. Even after accounting for the effect of the mediators, there is still a direct effect of parenting on both warm/loving and hostile/aggressive interactions with romantic partner. Implications for theory and practice are discussed. PMID:24730381

  2. Factors Linking Childhood Experiences to Adult Romantic Relationships among African Americans

    PubMed Central

    Simons, Leslie Gordon; Simons, Ronald L.; Landor, Antoinette M.; Bryant, Chalandra M.; Beach, Steven R.H.

    2014-01-01

    It is well known that a high quality relationship with a romantic partner is related to a variety of positive outcomes associated with health and well-being. Establishing such relationships is an important developmental task for young adults and past research indicates that there is a link between experiences in the family of origin and the success of later intimate relationships. It has been suggested that this association can be explained by the acquisition of social competencies (e.g., emotions, schemas, traits) that are acquired during childhood in the family of origin and, in turn, influence interaction with adult romantic partners. The current study builds on this foundation by identifying particular competencies expected to explain the association between childhood exposure to supportive and harsh parenting and later patterns of interaction with romantic partners. Specifically, we examine anger management, attachment style, hostile attribution bias, and self-control as potential mediators using prospective, longitudinal data from a sample of 345 African American young adults. Results from structural equation modeling indicate that each of the mediators in our study accounts for a significant portion of the effect of parenting on the quality of adult romantic relationships although the constructs linking parenting to warm interactions with romantic partners are somewhat different from those that link parenting to hostile interactions with romantic partners. Even after accounting for the effect of the mediators, there is still a direct effect of parenting on both warm/loving and hostile/aggressive interactions with romantic partner. Implications for theory and practice are discussed. PMID:24730381

  3. [Surgical treatment of priapism: experience of 56 cases in an African setting].

    PubMed

    Falandry, L; Berlizot, P; Fournier, R; Mechali, P; Thuret, R; Palascak, R; Houlgatte, A

    2000-01-01

    Since priapism is uncommon, treatment is controversial and difficult. In this article we describe a practical, well-documented approach for management of priapism in countries with a high incidence of sickle cell disease. This approach is based on our experience including a total of 56 black patients (49 adults and 7 children) as well as on the results reported in the literature. The patients in our series were examined and treated by the same physician over an 18 year period in various African countries, i.e., Burkina (n = 8), Chad (n = 12), Gabon (n = 19), and Niger (n = 17). Etiologies and pathophysiology are reviewed. In all cases, surgical treatment involved diversion from corpora cavernosa. In the 51 cases with follow-up periods of 3 months or longer, results were considered as excellent in 17 cases (33 p. 100), partial in 5 (9.8 p. 100), and unsuccessful in 29 (56.8). Since 1984, needle drainage with a unilateral transglandular cavernosal-spongiosum shunt based on the technique described by Al Ghorab's has led to better results with immediate detumescence in 80 p. 100 of cases and a long-term success rate of 52 p. 100 (13/25 cases with sufficient follow-up). Except in cases involving sickle cell anemia in which concomitant medical treatment of priapism can be useful, immediate surgical treatment is the only technique effective in avoiding secondary impotence, which was common in our series (58.6). Our p. 100 needle drainage technique appears to be the method of choice for simplified achievement of a unilateral transglandular cavernosal-spongiosum shunt. PMID:10989793

  4. Understanding the African American Research Experience (KAARE): Implications for HIV Prevention

    PubMed Central

    Kerkorian, Dara; Traube, Dorian E.; McKay, Mary M.

    2010-01-01

    SUMMARY Despite recognition that the African American population is underrepresented in studies of health and mental health treatment and prevention efforts, few investigations have systematically examined barriers to African American research participation. Without their participation, treatment and prevention strategies designed to curtail the spread of HIV in their communities will be bound to achieve less than optimal outcomes. Based on the assumption that successful recruitment of African Americans requires knowledge of (a) their beliefs about research, (b) their perceptions of the research process and researchers, (c) their motivations to participate, and (d) the historical and social factors that may be the source of at least some ambivalence, the current study undertook semi-structured interviews with 157 African American, low-income mothers residing in a large urban community where they and their children were at high risk for HIV. Given the sensitive nature of the research topic, members of the community were trained to conduct the interviews. Qualitative and quantitative analyses of the interview content suggest that despite having been consented, many participants (a) are not aware of their rights under informed consent and (b) lack knowledge of how the research will be used. Despite this and the subtle suspicion of White researchers held by some, many decide to participate for altruistic reasons. The implications for recruitment of participants in general and African Americans in particular into HIV prevention studies are discussed as are the implications for service providers directly or indirectly involved in the development and delivery of these interventions. PMID:20871788

  5. Fault rupture as a series of nano-seismic events during high-velocity shear experiments

    NASA Astrophysics Data System (ADS)

    Zu, X.; Reches, Z.; Chen, X.; Chang, J. C.; Carpenter, B. M.

    2015-12-01

    The rupture process of experimental faults is investigated here by monitoring nano-seismic events (NSE) during slip in a rotary shear apparatus. Our experimental faults are made of two rock blocks with one to four miniature 3D accelerometers that are glued to the stationary block at distance of ~ 2 cm from the fault surface. Accelerations in the frequency range of 1 Hz to 200 kHz are recorded in slip-parallel (x), slip-transverse (y), and slip-vertical (z) directions. We conducted a series of 45 experiments on diorite and dolomite samples in two loading styles: classical velocity controlled loading, and power-density loading, in which the power-density (shear stress times slip velocity) is selected, and stick-slip events develop spontaneously according to the experimental fault response. The 3D accelerometer data were recorded at 106 samples/s, with acceleration resolution of 10 mV/g in recoding range of +/- 5 V. The experiments were conducted at slip-velocity of 0.001-0.8 m/s and slip distance up to 1.38 m. The accelerometer observations revealed tens to hundreds of NSEs per slip in both loading styles; peak acceleration ranged from 1g to over 500g. A typical stick-slip with tens of NSEs in Fig. 1, shows: (1) An initial NSE at ~59.72 s (green) that coincides with a small stress drop (~10%, red); (2) Simultaneous macroscopic slip initiation (blue); (3) A swarm of NSEs occur as the fault slips, each NSE lasts 1-2 milliseconds; and (4) Details of the initial NSE are shown in Fig. 2. Based on waveform cross-correlation between frequency band from 20 kHz to 70kHz, we identify several groups of NSE clusters, and apply empirical Green's function method to analyze event source spectra based on Brune-type source model. These NSEs are indicators of rupture propagation during the experimental fault slip.

  6. Moonquakes and lunar tectonism results from the Apollo passive seismic experiment.

    NASA Technical Reports Server (NTRS)

    Latham, G.; Ewing, M.; Dorman, J.; Lammlein, D.; Press, F.; Toksoz, N.; Sutton, G.; Duennebier, F.; Nakamura, Y.

    1972-01-01

    The natural seismicity of the moon appears to be very low relative to that of the earth. However, moonquakes do occur. They are detected by the stations of the Apollo seismic network at an average rate of 1800/yr at Station 14 and at lower rates at Stations 12 and 15. All of the moonquakes are small, and in the few cases for which the foci have been located, they occur at great depth (about 800 km). The frequency of occurrence of moonquakes is strongly correlated with lunar tides. The dynamic processes that generate quakes are clearly much less vigorous within the moon than they are within the earth.

  7. Planning the improvement of seismic monitoring in a volcanic supersite: experience on Mt. Etna

    NASA Astrophysics Data System (ADS)

    D'Alessandro, Antonino; Scarfi, Luciano; Scaltrito, Antonio; Aiesi, Giampiero; Di Prima, Sergio; Ferrari, Ferruccio; Rapisarda, Salvatore

    2013-04-01

    Etna is one of the most active volcanoes in the world and one of the most intriguing natural laboratories for the understanding of eruptive processes and lava uprising in basalt-type volcanic environments; indeed, it is considered, by the scientific international community, together with the Vesuvius and the Hawaiian Islands, as a volcanic supersite. Its activity is continuously monitored by the Osservatorio Etneo of the Istituto Nazionale di Geofisica e Vulcanologia (INGV), by means of an array of integrated multidisciplinary techniques. In particular, Etna seismicity is recorded by a dense local seismic network (ESN- Etna Seismic Network), which, nowadays, consists of about 40 real-time seismic stations, many of which equipped with broadband velocity and accelerometer sensors. The data are analyzed routinely in detail by the Osservatorio Etneo staff, producing daily and periodic reports and bulletins of the earthquakes located in the whole Sicily and southern Calabria region. In the last decades, seismological observations provided important information on both the dynamics and internal structure of the volcano, in addition to their interaction with the regional tectonic structures. In the last year, in the framework of the VULCAMED project, an INGV workgroup has taken on the task of developing the existing seismic network through the installation of new measurement stations. By considering the spatial distribution of earthquakes in the area, the presence of structures known as seismically active and through extensive geological-geophysical surveys, ten potential new sites were identified. In the following months, some of these sites will complement the existing network. The choice of optimal sites must clearly be made through a careful analysis of environmental noise, of the possible logistics, technical and broadcast problems, but must also take into account the geometry of the existing seismic network. For this purpose, we applied the Seismic Network

  8. U. S. Geological Survey begins seismic ground response experiments in Washington State

    USGS Publications Warehouse

    Tarr, A.C.; King, K.W.

    1987-01-01

    The men were Denver-based U.S Geological Survey (USGS) geophysicists working on the Urban Hazards Field Investigations project. On the previous day they had recorded two events on their seismographs-a distant nuclear explosion in Nevada and a blast at amine near Centralia, Washington. On another day, they used seismic refraction equipment to locate the depth of bedrock and seismic velocity to it at several locations in West Seattle and in the Seward Park-Brighton district of southeast Seattle. 

  9. Ghana's experience in the establishment of a national digital seismic network observatory

    NASA Astrophysics Data System (ADS)

    Ahulu, Sylvanus; Danuor, Sylvester Kojo

    2015-07-01

    The Government of Ghana has established a National Digital Seismic Network Observatory in Ghana with the aim of monitoring events such as earthquakes, blasts from mining and quarrying, nuclear tests, etc. The Digital Observatory was commissioned on 19 December 2012, and was dedicated to Geosciences in Ghana. Previously Ghana did not have any operational, digital seismic network acquisition system with the capability of monitoring and analysing data for planning and research purposes. The Ghana Geological Survey has been monitoring seismic events with an analogue system which was not efficient and does not deliver real-time data. Hence, the importance of setting up the National Digital Seismic Network System which would enable the Geological Survey to constantly monitor, manage and coordinate both natural and man-made seismic activities in the country and around the globe, to some extent on real-time basis. The Network System is made up of six remote digital stations that transmit data via satellite to the central observatory. Sensors used are 3× Trillium Compact and 3× Trillium 120PA with Trident digitizers. The department has also acquired strong motion equipment: Titan accelerometers with Taurus digitizers from Nanometrics. Three of each of these instruments have been installed at the Akosombo and Kpong hydrodams, and also at the Weija water supply dam. These instruments are used to monitor dams. The peak ground acceleration (PGA) values established from the analysed data from the accelerometers will be used to retrofit or carry out maintenance work of the dam structures to avoid collapse. Apart from these, the observatory also assesses and analyses seismic waveforms relevant to its needs from the Global Seismographic Network (GSN) system operated by the US Geological Survey. The Ghana Geological Survey, through its Seismic Network Observatory makes data available to its stakeholder institutions for earthquake disaster mitigation; reports on all aspects of

  10. Sexual Decision Making in the Absence of Choice: The African American Female Dating Experience

    PubMed Central

    Andrasik, Michele P.; Nguyen, Hong V.; George, William H.; Kajumulo, Kelly F.

    2016-01-01

    Although links between low mate availability and increased HIV and STI risk for African American women have been documented in the literature, we know little about the impact of limited mate choices on the quality of relationships between Black men and women and how these relationship dynamics impact risk for young Black women. We conducted a qualitative study with African American female young adults (N=12) to explore the perceived impact of structural forces on African American female young adults’ dating and sexual behavior. Participants reported (1) perceptions of Black men as untrustworthy and manipulative, (2) the limited and often negative roles for Black men in the larger Black community, and (3) heterosexual relationships in the Black community as increasingly influenced by economics and commerce. Recommendations for HIV prevention interventions that include micro and macro level approaches are discussed. PMID:27182463

  11. In/dependent Collaborations: Perceptions and Experiences of African Scientists in Transnational HIV Research

    PubMed Central

    Moyi Okwaro, Ferdinand; Geissler, P. W.

    2015-01-01

    This article examines collaboration in transnational medical research from the viewpoint of African scientists working in partnerships with northern counterparts. It draws on ethnographic fieldwork in an HIV laboratory of an East African state university, with additional data from interviews with scientists working in related research institutions. Collaboration is today the preferred framework for the mechanisms by which northern institutions support research in the south. The concept signals a shift away from the legacy of unequal (post‐) colonial power relations, although, amid persisting inequalities, the rhetorical emphasis on equality might actually hinder critical engagement with conflicts of interest and injustice. To collaborate, African scientists engage various strategies: They establish a qualified but flexible, non‐permanent workforce, diversify collaborators and research areas, source complementary funding to assemble infrastructures, and maintain prospective research populations to attract transnational clinical trials. Through this labor of collaboration, they sustain their institutions under prevailing conditions of scarcity. PMID:25800667

  12. Modelling Active Faults in Probabilistic Seismic Hazard Analysis (PSHA) with OpenQuake: Definition, Design and Experience

    NASA Astrophysics Data System (ADS)

    Weatherill, Graeme; Garcia, Julio; Poggi, Valerio; Chen, Yen-Shin; Pagani, Marco

    2016-04-01

    The Global Earthquake Model (GEM) has, since its inception in 2009, made many contributions to the practice of seismic hazard modeling in different regions of the globe. The OpenQuake-engine (hereafter referred to simply as OpenQuake), GEM's open-source software for calculation of earthquake hazard and risk, has found application in many countries, spanning a diversity of tectonic environments. GEM itself has produced a database of national and regional seismic hazard models, harmonizing into OpenQuake's own definition the varied seismogenic sources found therein. The characterization of active faults in probabilistic seismic hazard analysis (PSHA) is at the centre of this process, motivating many of the developments in OpenQuake and presenting hazard modellers with the challenge of reconciling seismological, geological and geodetic information for the different regions of the world. Faced with these challenges, and from the experience gained in the process of harmonizing existing models of seismic hazard, four critical issues are addressed. The challenge GEM has faced in the development of software is how to define a representation of an active fault (both in terms of geometry and earthquake behaviour) that is sufficiently flexible to adapt to different tectonic conditions and levels of data completeness. By exploring the different fault typologies supported by OpenQuake we illustrate how seismic hazard calculations can, and do, take into account complexities such as geometrical irregularity of faults in the prediction of ground motion, highlighting some of the potential pitfalls and inconsistencies that can arise. This exploration leads to the second main challenge in active fault modeling, what elements of the fault source model impact most upon the hazard at a site, and when does this matter? Through a series of sensitivity studies we show how different configurations of fault geometry, and the corresponding characterisation of near-fault phenomena (including

  13. Passive, broad-band seismic measurements for geothermal exploration : The GAPSS experiment

    NASA Astrophysics Data System (ADS)

    Saccorotti, Gilberto; Piccinini, Davide; Zupo, Maria; Mazzarini, Francesco; Cauchie, Lena; Chiarabba, Claudio; Piana Agostinetti, Nicola

    2014-05-01

    Passive seismological imaging techniques based on either transient (earthquakes) or sustained (background noise) signals can provide detailed descriptions of subsurface attributes as seismic velocity, attenuation, and anisotropy. However, the correspondence between these parameters and the physical properties of crustal fluids is still ambiguous. Moreover, the resolving capabilities and condition of applicability of emerging techniques such as the Ambient Noise Tomography are still to be investigated thoroughly. Following these arguments, a specific project (GAPSS-Geothermal Area Passive Seismic Sources) was planned, in order to test passive exploration methods on a well-known geothermal area, namely the Larderello-Travale Geothermal Field (LTGF). This geothermal area is located in the western part of Tuscany (Italy), and it is the most ancient geothermal power field of the world. Heat flow in this area can reach local peaks of 1000 mW/m3. The deep explorations in this area showed a deeper reservoir (3000 to 4000 m depth) located within the metamorphic rocks in the contact aureole of the Pliocene-Quaternary granites; it is characterized by a wide negative gravimetric anomaly, interpreted as partially molten granite at temperatures of 800°C. From seismic surveys the K-marker K (pressurized horizons) was found at depths between 3 and 7 km. The structural grain of the geothermal field is characterized by N-W trending and N-E dipping normal faults whose activity lasts since the Pliocene. GAPSS lasted from early May, 2012, through October, 2013. It consisted of up to 20 temporary seismic stations, complemented by two permanent stations from the National Seismic Network of Italy. The resulting array has an aperture of about 50 Km, with station spacings between 2 and 50 km. Stations are equipped with either broadband (40s and 120s) or intermediate-period (5s), 3-components seismometers. LTGF is seismically active. During the first 10 months of measurements, we located

  14. Localization of short-range acoustic and seismic wideband sources: Algorithms and experiments

    NASA Astrophysics Data System (ADS)

    Stafsudd, J. Z.; Asgari, S.; Hudson, R.; Yao, K.; Taciroglu, E.

    2008-04-01

    We consider the determination of the location (source localization) of a disturbance source which emits acoustic and/or seismic signals. We devise an enhanced approximate maximum-likelihood (AML) algorithm to process data collected at acoustic sensors (microphones) belonging to an array of, non-collocated but otherwise identical, sensors. The approximate maximum-likelihood algorithm exploits the time-delay-of-arrival of acoustic signals at different sensors, and yields the source location. For processing the seismic signals, we investigate two distinct algorithms, both of which process data collected at a single measurement station comprising a triaxial accelerometer, to determine direction-of-arrival. The direction-of-arrivals determined at each sensor station are then combined using a weighted least-squares approach for source localization. The first of the direction-of-arrival estimation algorithms is based on the spectral decomposition of the covariance matrix, while the second is based on surface wave analysis. Both of the seismic source localization algorithms have their roots in seismology; and covariance matrix analysis had been successfully employed in applications where the source and the sensors (array) are typically separated by planetary distances (i.e., hundreds to thousands of kilometers). Here, we focus on very-short distances (e.g., less than one hundred meters) instead, with an outlook to applications in multi-modal surveillance, including target detection, tracking, and zone intrusion. We demonstrate the utility of the aforementioned algorithms through a series of open-field tests wherein we successfully localize wideband acoustic and/or seismic sources. We also investigate a basic strategy for fusion of results yielded by acoustic and seismic arrays.

  15. Academically Successful African American Male Urban High School Students' Experiences of Mattering to Others at School

    ERIC Educational Resources Information Center

    Tucker, Catherine; Dixon, Andrea; Griddine, Ke'Shana

    2010-01-01

    Mattering to others has been shown to be a key construct of mental health and wellness. Emerging research links interpersonal mattering and school climate. In this study, the authors use transcendental phenomenology to explore how interpersonal mattering impacts the academic achievement of urban African American males who are academically…

  16. The Influence of Both Race and Gender on the Experiences of African American College Women.

    ERIC Educational Resources Information Center

    Jackson, Lisa R.

    1998-01-01

    At four colleges, 135 African American women students completed measures of self-concept, gender identity, and ethnic identity, and were interviewed. Results suggest that women's self-concepts of race and gender are experienced differently depending on their school's racial and gender composition. Colleges should reexamine diversity efforts to…

  17. What Makes African American Health Disparities Newsworthy? An Experiment among Journalists about Story Framing

    ERIC Educational Resources Information Center

    Hinnant, Amanda; Oh, Hyun Jee; Caburnay, Charlene A.; Kreuter, Matthew W.

    2011-01-01

    News stories reporting race-specific health information commonly emphasize disparities between racial groups. But recent research suggests this focus on disparities has unintended effects on African American audiences, generating negative emotions and less interest in preventive behaviors (Nicholson RA, Kreuter MW, Lapka C "et al." Unintended…

  18. Sense of Belonging and Student Success: An Analysis of Student Experiences in South African Universities

    ERIC Educational Resources Information Center

    Williams, Theresa

    2012-01-01

    Retention and graduation are major challenges in South African higher education institutions. These phenomena are especially troubling among Black and Colored (BC) students at both historically advantaged and historically disadvantaged institutions. The retention and graduation rates of these groups are disturbingly low compared to those of White…

  19. Towards a Meaningful Curriculum Implementation in South African Schools: Senior Phase Teachers' Experiences

    ERIC Educational Resources Information Center

    Taole, Matshidiso Joyce

    2015-01-01

    Different sectors of society register complaints about schooling in South Africa. Given that curriculum reform has such a poor record of implementation in the country, there is clearly a need for research that identifies factors that hinder or facilitate curriculum implementation in South African schools and identifies strategies to address the…

  20. Scaffolding the Home Reading Experiences of African-American First Graders

    ERIC Educational Resources Information Center

    Dunston, Yolanda L.; Patterson, Gerrelyn C.; Daniels, Kisha N.

    2010-01-01

    This study explored the feedback provided by sixty African American mothers as they listened to their first grade children read aloud from a grade level text. Maternal feedback fell into two distinct groups. Children with higher oral reading accuracy levels on the text had mothers who more frequently waited and permitted opportunities for the…

  1. African American Faculty Women Experiences of Underrepresentation in Computer Technology Positions in Higher Education

    ERIC Educational Resources Information Center

    King, Dolores

    2013-01-01

    African American women are underrepresented in computer technology disciplines in institutions of higher education throughout the United States. Although equitable gender representation is progressing in most fields, much less information is available on why institutions are still lagging in workforce diversity, a problem which can be lessened by…

  2. Till Death Do Us Part: Lived Experiences of HIV-Positive Married African American Women

    ERIC Educational Resources Information Center

    Edwards, Lorece V.; Irving, Shalon M.; Hawkins, Anita S.

    2011-01-01

    HIV/AIDS disease continues to be an escalating health problem, particularly among women. However, African American women are among the leading demographic groups for HIV prevalence in the United States. The typical woman with HIV/AIDS is young, in her late twenties, economically challenged, and of childbearing age. Participants were recruited from…

  3. Early Educational Foundations for the Development of Civic Responsibility: An African Experience

    ERIC Educational Resources Information Center

    Serpell, Robert; Mumba, Paul; Chansa-Kabali, Tamara

    2011-01-01

    An innovative curriculum designed to foster the development of social responsibility among pre-adolescent children was introduced at a rural Zambian primary school. The curriculum invoked Child-to-Child principles focusing on health education, advancing a synthesis of Western psychological theories and African cultural traditions. The teacher…

  4. The Experiences of African American Physical Education Teacher Candidates at Secondary Urban Schools

    ERIC Educational Resources Information Center

    Sato, Takahiro; Fisette, Jennifer; Walton, Theresa

    2013-01-01

    Presently, most physical education teachers in the United States are White Americans and from middle class families. In fact, 83% of all teachers in public schools are White Americans, whereas approximately 10% of all African American teachers are representative of all teachers in the United States. A student might feel cultural dissonance that…

  5. The Power of Peers: Influences on Postsecondary Education Planning and Experiences of African American Students

    ERIC Educational Resources Information Center

    Holland, Nicole E.

    2011-01-01

    This investigation demonstrates the effect that peers have on students' academic engagement and educational aspirations. Forty-nine African American university students retrospectively discuss the manner by which their friends influenced their academic commitment and activity while in high school; their postsecondary education aspirations,…

  6. A Dream Deferred: The Experience of an African American Student in a Doctoral Program in Science

    ERIC Educational Resources Information Center

    Green, Andre M.

    2008-01-01

    Due to a negative stigma that has been established about African Americans, many live their entire lives trying to "refute the degrading, humiliating and offensive racial images and stereotypes" that have plagued their race in scientific fields and in other areas of life. The images that are perpetuated have caused frustration as well as…

  7. A Bourdieusian Approach to Academic Reading: Reflections on a South African Teaching Experience

    ERIC Educational Resources Information Center

    Hill, Lloyd; Meo, Analía Inés

    2015-01-01

    As in many other parts of the world, "academic literacy" has emerged as both a concern and a contested concept in South African universities. In this article we focus specifically on academic reading, which we argue is a relatively underemphasized aspect of academic literacy. This article is the product of reflections on academic reading…

  8. A Survey of the Experiences of African Librarians in American Academic Libraries

    ERIC Educational Resources Information Center

    Ibraheem, Abiodun I.; Devine, Christopher

    2013-01-01

    A national research study was undertaken to identify and clarify issues related to the employment in academic settings of African librarians who have relocated to the United States. It examined, by means of a survey, employment issues concerned with education, credentialing, language skills and cultural bias from the perspective of those…

  9. The Stuff of Stereotypes: Toward Unpacking Identity Threats amid African American Students' Learning Experiences

    ERIC Educational Resources Information Center

    Larnell, Gregory V.; Boston, Denise; Bragelman, John

    2014-01-01

    The purpose of this article is to shed light on scenarios in which threatening stereotypes unfold, specifically in an institutional context in which African Americans are overrepresented. Drawing on data and findings from a recent study examining mathematics learning and identity in non-credit-bearing remedial math courses, we present three…

  10. The Invisible Wall: Exploring the Experiences of African-American Students at CCCU Institutions

    ERIC Educational Resources Information Center

    Young, Timothy Perry

    2013-01-01

    African-American students who attend a CCCU institution do not complete their degrees as frequently as other student groups. The average gap at CCCU institutions between "overall and Black graduation rates is more than 19%. This is greater than the gap at other private institutions" (Smith, 2009, p.80). While the six-year graduation rate…

  11. Examining Both Race and Gender in the Experiences of African American College Women.

    ERIC Educational Resources Information Center

    Jackson, Lisa R.

    This study examined how African American women defined who they were in their respective college contexts, focusing on the roles of gender, race, and institutional type. A total of 20 women from a white coeducational institution, a predominantly white women's college, and a coeducational, historically black college participated in in-depth…

  12. Men of the Cloth: African-American Clergy's Knowledge and Experience in Providing Pastoral Care to African-American Elders with Late-Life Depression

    ERIC Educational Resources Information Center

    Stansbury, Kim L.

    2011-01-01

    African-American clergy's ability to recognize late-life depression and their capacity to provide support with this illness have been neglected in the literature. Using a mental health literacy framework, the purpose of this research was to explore African-American clergy's knowledge of and treatments for late-life depression. In-depth interviews…

  13. Time-frequency-wavenumber Decomposition To Investigate Seismic Wavefield: Application To The Annot Experiment

    NASA Astrophysics Data System (ADS)

    Schissele, E.; Cansi, Y.; Gaffet, S.

    Many observations and studies as well as numerical simulations have been done in order to completely understand the whole seismogram recorded during an earthquake. At regional distances, the seismic wavefield is strongly influenced by crustal hetero- geneities. The primary wavefield constituted by Pn, Pg, Sn, Sg, Rg, Lg.... phases is diffracted and refracted by these heterogeneities and hence forms the coda of the seis- mogram. But the different mechanisms of propagation in a heterogeneous medium are not fully understood. The identification of the different phases contributing to the coda seems to be essential to progress in the comprehension of the seismic wavefield propagation. Seismic arrays are then well-adapted tools since they provide the spatio-temporal evo- lution of the wavefield. In 1998, 4 small-scales arrays were deployed for 2 months around the Annot region, located in the southern French Alps. Each array was constituted by 9 short-period seismometers, recording frequencies greater than 0.2 Hz. Its aperture was 250 meters, with a minimal distance between 2 adjacent sensors of 20 meters. That allows us to study the seismic wavefield for very low wavelength without any problem of spatial aliasing. It will be interesting to characterize in terms of wavefield deformation the signature of the different kinds of heterogeneities (fault system, topographic relief, impedance contrast...) surrounding this area. We expect the primary wavefield to be diffracted or refracted by all these heterogeneities. A time-frequency-wavenumber technique which allows us to characterize the whole coherent part of the energy which prop- agates through the seismic array has been derived. Such a characterization involves, for each coherent wavelet, an estimate of: (i) an arrival time and a frequency content and (ii) an azimuth and an apparent velocity. This way, the principal phases will be described. What will be more interesting, is the extraction of the deterministic part of the

  14. Crust structure across the Rif Cordillera from 'RIFSIS' seismic refraction and wide-angle reflection experiment

    NASA Astrophysics Data System (ADS)

    Gil, Alba; Gallart, Josep; Díaz, Jordi; Carbonell, Ramon; Harnafi, Mimoun; Levander, Alan

    2013-04-01

    The Rif Cordillera, located in North Morocco forms, together with the Betic Range, the Gibraltar Arc around the Alboran Sea. This asymmetric curved mountain belt originated during a Miocene continent-continent collision as a result of the westward motion of the Alboran domain between northwest Africa and Iberia. The complexity of the area favored the proposition of diverse tectonic models, such as roll-back, accompanied and followed by lithospheric convective down-welling, and delamination. In this study, we present models of crustal structure derived from a seismic refraction and wide-angle reflection experiment which took place in October 2011 within the Spanish project RIFSIS complemented by the US-PICASSO one. Two profiles oriented N-S and E-W respectively were carried out across the Rif domains. Five shots of 1 Tn each were detonated along the lines and at the crossing point, recorded by about 900 stations from US-Iris pool deployed at an average spacing of 750 m. The N-S line was extended northwards by a 70 km long segment in Spain, in the Betic Range. Southwards, this profile connects with the one recorded in 2010 across the Atlas Mountains, within the SIMA project. The interpreted crustal structure differentiates two sedimentary layers on top of the basement, inferred from the observed first arrivals at short offsets, followed by upper, mid and lower crustal levels constrained by reflected phases visible in the record sections. The bottom of the crust is well defined from PmP phases, although the absence of Pn arrivals prevents to constrain upper mantle velocities. Average velocity values for the different layers in the models are respectively: 3.5 and 4.2 km/s for the sediments, 5.9, 6.3 and 6.6 km/s within the crust, and 8 km/s below Moho. These velocity depth models obtained at the Rif Cordillera hold major variations in crustal thickness, especially along the E-W profile, that shows a rapid change of 15-20 km in Moho depths within 30 km horizontal

  15. Early sexual experience and later onset of illegal drug use among African American students on HBCU campuses.

    PubMed

    Wang, Yan; Storr, Carla; Browne, Dorothy C; Wagner, Fernando A

    2011-01-01

    Few studies examine whether early sexual experience is associated with subsequent illegal drug use among adolescents. A sample of 7,372 African American students who had not used illegal drugs before the age of 14 were identified in the dataset of the 2001 Historically Black Colleges and Universities (HBCU) Substance Use Survey. Using self-reported ages of onset, discrete-time survival models estimated the hazard of illegal drug use onset after age 13 subsequent to first sexual intercourse. Early sex was modestly associated with subsequent illegal drug initiation, particularly among females. Drug use prevention services should be provided to youth engaged in early sexual activity. PMID:20735190

  16. Deviant bodies, stigmatized identities, and racist acts: examining the experiences of African-American gamers in Xbox Live

    NASA Astrophysics Data System (ADS)

    Gray, K. L.

    2012-12-01

    The purpose of this article is to illustrate how minority gamers, particularly African-American males, are subject to the label of deviant within the virtual gaming community of Xbox Live. They are labeled deviant based on the stigma of their physical identity - blackness, through a process of linguistic profiling. By employing virtual ethnography, the author identifies a process that leads to racism based on how the black gamer sounds within the space. The act of racism emerges through a process involving questioning, provoking, instigating, and ultimately racism. Many black gamers have normalized these racist experiences and have accepted the label of deviant placed upon their bodies.

  17. Rocky Mountain evolution: Tying Continental Dynamics of the Rocky Mountains and Deep Probe seismic experiments with receiver functions

    USGS Publications Warehouse

    Rumpfhuber, E.-M.; Keller, Gordon R.; Sandvol, E.; Velasco, A.A.; Wilson, D.C.

    2009-01-01

    In this study, we have determined the crustal structure using three different receiver function methods using data collected from the northern transect of the Continental Dynamics of the Rocky Mountains (CD-ROM) experiment. The resulting migrated image and crustal thickness determinations confirm and refine prior crustal thickness measurements based on the CD-ROM and Deep Probe experiment data sets. The new results show a very distinct and thick lower crustal layer beneath the Archean Wyoming province. In addition, we are able to show its termination at 42??N latitude, which provides a seismic tie between the CD-ROM and Deep Probe seismic experiments and thus completes a continuous north-south transect extending from New Mexico into Alberta, Canada. This new tie is particularly important because it occurs close to a major tectonic boundary, the Cheyenne belt, between an Archean craton and a Proterozoic terrane. We used two different stacking techniques, based on a similar concept but using two different ways to estimate uncertainties. Furthermore, we used receiver function migration and common conversion point (CCP) stacking techniques. The combined interpretation of all our results shows (1) crustal thinning in southern Wyoming, (2) strong northward crustal thickening beginning in central Wyoming, (3) the presence of an unusually thick and high-velocity lower crust beneath the Wyoming province, and (4) the abrupt termination of this lower crustal layer north of the Cheyenne belt at 42??N latitude. Copyright 2009 by the American Geophysical Union.

  18. The Impact of African American Parents' Racial Discrimination Experiences and Perceived Neighborhood Cohesion on their Racial Socialization Practices.

    PubMed

    Saleem, Farzana T; English, Devin; Busby, Danielle R; Lambert, Sharon F; Harrison, Aubrey; Stock, Michelle L; Gibbons, Frederick X

    2016-07-01

    Parental racial socialization is a parenting tool used to prepare African American adolescents for managing racial stressors. While it is known that parents' racial discrimination experiences affect the racial socialization messages they provide, little is known about the influence of factors that promote supportive and communal parenting, such as perceived neighborhood cohesion. In cohesive neighborhoods, neighbors may help parents address racial discrimination by monitoring youth and conveying racial socialization messages; additionally, the effect of neighborhood cohesion on parents' racial socialization may differ for boys and girls because parents socialize adolescents about race differently based on expected encounters with racial discrimination. Therefore, the current study examines how parents' perception of neighborhood cohesion and adolescents' gender moderate associations between parents' racial discrimination experiences and the racial socialization messages they deliver to their adolescents. Participants were a community sample of 608 African American adolescents (54 % girls; mean age = 15.5) and their primary caregivers (86 % biological mothers; mean age = 42.0). Structural equation modeling indicated that parental racial discrimination was associated with more promotion of mistrust messages for boys and girls in communities with low neighborhood cohesion. In addition, parental racial discrimination was associated with more cultural socialization messages about racial pride and history for boys in neighborhoods with low neighborhood cohesion. The findings suggest that parents' racial socialization messages are influenced by their own racial discrimination experiences and the cohesiveness of the neighborhood; furthermore, the content of parental messages delivered varies based on adolescents' gender. PMID:27189721

  19. Theory and experiment of an inertia-type vertical isolation system for seismic protection of equipment

    NASA Astrophysics Data System (ADS)

    Lu, Lyan-Ywan; Chen, Pei-Rong; Pong, Kuan-Wen

    2016-03-01

    Although it has been proven that seismic isolation is an effective technology for seismic protection of structures and equipment, most existing isolation systems are for mitigating horizontal ground motions, and in practice there are very few vertical isolation systems. Part of the reason is due to the conflict with regard to the demand for isolation stiffness. In other words, a vertical isolation system must have sufficient vertical rigidity to sustain the weight of the isolated object, while it must also have sufficient flexibility in order to elongate the vibration period under seismic excitation. In order to overcome this difficulty, a novel system is proposed in this study, called an inertia-type vertical isolation system (IVIS). The primary difference between the IVIS and a traditional system is that the former has an additional leverage mechanism with a counterweight. The counterweight will provide a static uplifting force and an extra dynamic inertia force, such that the effective vertical stiffness of the IVIS becomes higher in its static state and lower in the dynamic one. The theory underlying the IVIS is developed and verified experimentally by a seismic simulation test in this work. The results show that the IVIS leads to a less static settlement and at the same time a lower effective isolation frequency. The test results also demonstrate that the isolator displacement demand of the IVIS is only about 30-40 percent that of the traditional one in all kinds of earthquakes. With regard to the reduction of acceleration response, the IVIS is particularly effective for near-fault earthquakes or near-resonant excitations, but is less effective for far-field earthquakes with more high-frequency contents, as compared with the traditional system.

  20. Passive seismic experiment - A summary of current status. [Apollo-initiated lunar surface station data

    NASA Technical Reports Server (NTRS)

    Latham, G. V.; Dorman, H. J.; Horvath, P.; Ibrahim, A. K.; Koyama, J.; Nakamura, Y.

    1978-01-01

    The data set obtained from the four-station Apollo seismic network including signals from approximately 11,800 events, is surveyed. Some refinement of the lunar model will result, but its gross features remain the same. Attention is given to the question of a small, molten lunar core, the answer to which remains dependent on analysis of signals from a far side impact. Seventy three sources of repeating, deep moonquakes have been identified, thirty nine of which have been accurately located. Concentrated at depths from 800 to 1000 km, the periodicities of these events have led to the hypothesis that they are generated by tidal stresses. Lunar seismic data has also indicated that the meteoroid population is ten times lower than originally determined from earth based observations. Lunar seismic activity is much lower and mountainous masses show no sign of sinking, in contrast to earth, as a result of the lunar crust being four times thicker. While much work remains to be done, significant correlation between terrestrial and lunar observations can be seen.

  1. A population-based analysis of the health experience of African Nova Scotians

    PubMed Central

    Kisely, Steve; Terashima, Mikiko; Langille, Don

    2008-01-01

    Background People of African descent living in Britain and the United States have higher rates of morbidity from chronic disease than among the general population. We investigated whether the same applied to people of African descent living in a Canadian province. Methods We used administrative data to calculate 10-year cumulative incidence rate ratios for the period 1996–2005 for treated circulatory disease, diabetes mellitus and psychiatric disorders in Preston (population 2425), a community of predominantly African Nova Scotians. We used data for the province of Nova Scotia as a whole as the population reference standard. We also calculated 10-year incidence rate ratios for visits to family physicians and specialists and for admissions to hospital. We compared these findings with those in 7 predominantly white communities in Nova Scotia with otherwise similar socio-economic characteristics. Results In the province as a whole, we identified 787 787 incident cases for the 3 disease groups over the 10-year period. Incidence rate ratios for the community of interest relative to the provincial population were significantly elevated for the 3 diseases: circulatory disease (1.19, 95% CI 1.08–1.29), diabetes (1.43, 95% CI 1.21–1.64) and psychiatric disorders (1.13, 95% CI 1.06–1.20). Incidence rate ratios in the community of interest were also higher than those in the comparison communities. Visits to family physicians and specialists for circulatory disease and diabetes were similarly elevated, but the pattern was less clear for visits for psychiatric disorders and hospital admissions. Interpretation African Nova Scotians had higher morbidity levels associated with treated disease, which could not be explained by socio-economic characteristics, recent immigration or language. Apart from psychiatric disorders, use of specialist services was consistent with morbidity. Further study is needed to investigate the relative contribution of genetic, biological

  2. Active source seismic experiment investigating the formation of the Ontong Java Plateau

    NASA Astrophysics Data System (ADS)

    Miura, S.; Noguchi, N.; Coffin, M. F.; Kawagle, S. A.; Verave, R. T.; Kodaira, S.; Fukao, Y.

    2010-12-01

    The Ontong Java Plateau (OJP) is one of the largest oceanic plateaus and possibly the most voluminous large igneous province (LIP) on Earth, and is thought to have formed by a non-plate tectonic mechanism such as 1) a plume head, 2) a bolide impact, or 3) atypical seafloor spreading. Due to massive magmatism over short durations of geological time, formations of the OJP and LIPs in general likely have had global scale environmental impacts (e.g., Oceanic Anoxic Events). Therefore, understanding how LIPs form is important not only for illuminating solid Earth processes, but also for advancing knowledge of associated environmental, including biospheric, changes. On the basis of the OJP’s shallow bathymetry, its crust has long been thought to be thicker than normal oceanic crust. However, previous seismic and gravimetric analyses of its crustal thickness produced inconsistent results. To understand how the OJP formed, we conducted a seismic survey using a multi-channel seismic (MCS) hydrophone streamer and 100 ocean bottom seismometers (OBS) in February-March 2010 (EOS, submitted). New MCS data confirm that sediment approximately 1 s (two-way travel time) thick covers the uppermost OJP. Sediment layers are generally flat-lying, except near seamounts, in a local depression, and around some faults. Because of the flat-lying seafloor and shallow water depths, several water-bottom multiples of large amplitude characterize the MCS data, making identification of sub-basement reflections challenging. On the northernmost part of the seismic line, a reflection event at about 12 s (two-way travel time) differs unambiguously from multiple reflections, and may represent the base of the OJP’s crust. OBS data show first refraction arrivals within 100-km offsets. First arrivals with an apparent velocity of 7 km/s can be identified at offsets greater than 100 km. This may indicate a thick high velocity (~7 km/s) layer in the OJP’s lower crust. This high velocity layer may be

  3. Fault structure, stress, or pressure control of the seismicity in shale? Insights from a controlled experiment of fluid-induced fault reactivation

    NASA Astrophysics Data System (ADS)

    De Barros, Louis; Daniel, Guillaume; Guglielmi, Yves; Rivet, Diane; Caron, Hervé; Payre, Xavier; Bergery, Guillaume; Henry, Pierre; Castilla, Raymi; Dick, Pierre; Barbieri, Ernesto; Gourlay, Maxime

    2016-06-01

    Clay formations are present in reservoirs and earthquake faults, but questions remain on their mechanical behavior, as they can vary from ductile (aseismic) to brittle (seismic). An experiment, at a scale of 10 m, aims to reactivate a natural fault by fluid pressure in shale materials. The injection area was surrounded by a dense monitoring network comprising pressure, deformation, and seismicity sensors, in a well-characterized geological setting. Thirty-two microseismic events were recorded during several injection phases in five different locations within the fault zone. Their computed magnitude ranged between -4.3 and -3.7. Their spatiotemporal distribution, compared with the measured displacement at the injection points, shows that most of the deformation induced by the injection is aseismic. Whether the seismicity is controlled by the fault architecture, mineralogy of fracture filling, fluid, and/or stress state is then discussed. The fault damage zone architecture and mineralogy are of crucial importance, as seismic slip mainly localizes on the sealed-with-calcite fractures which predominate in the fault damage zone. As no seismicity is observed in the close vicinity of the injection areas, the presence of fluid seems to prevent seismic slips. The fault core acts as an impermeable hydraulic barrier that favors fluid confinement and pressurization. Therefore, the seismic behavior seems to be strongly sensitive to the structural heterogeneity (including permeability) of the fault zone, which leads to a heterogeneous stress response to the pressurized volume.

  4. Rhythm experience and Africana culture trial (REACT!): A culturally salient intervention to promote neurocognitive health, mood, and well-being in older African Americans.

    PubMed

    Lukach, Alexis J; Jedrziewski, M Kathryn; Grove, George A; Mechanic-Hamilton, Dawn J; Williams, Shardae S; Wollam, Mariegold E; Erickson, Kirk I

    2016-05-01

    The Rhythm Experience and Africana Culture Trial (REACT!) is a multi-site randomized controlled intervention study designed to examine the efficacy of using African Dance as a form of moderate-intensity physical activity to improve cognitive function in older African Americans. African Americans are almost two times more likely than Caucasians to experience cognitive impairment in late adulthood. This increased risk may be attributed to lower level and quality of education, lower socioeconomic status, and higher prevalence of vascular diseases, type 2 diabetes, hypertension, and obesity, all of which are recognized as risk factors for dementia. Fortunately, interventions targeting cardiovascular health (i.e., physical activity) are associated with improved neurocognitive function and a reduced risk for dementia, so African Americans may be particularly suited for interventions targeting cardiovascular health and cognitive function. Here, we describe a randomized intervention protocol for increasing physical activity in older (65-75years) African Americans. Participants (n=80) at two study locations will be randomized into one of two groups. The treatment group will participate in African Dance three times per week for six months and the control group will receive educational training on Africana history and culture, as well as information about health behaviors, three times per week for six months. If successful, the REACT! study may transform community interventions and serve as a platform and model for testing other populations, age groups, and health outcomes, potentially identifying novel and creative methods for reducing or eliminating health disparities. PMID:27033674

  5. Broadband seismic experiment at Merapi Volcano, Java, Indonesia: very-long-period pulses embedded in multiphase earthquakes

    NASA Astrophysics Data System (ADS)

    Hidayat, D.; Voight, B.; Langston, C.; Ratdomopurbo, A.; Ebeling, C.

    2000-07-01

    Multiphase (MP) and low frequency (LF) earthquakes with spectral peak amplitudes at 3-4 and 1 Hz, respectively, are two common types of shallow volcanic earthquakes previously recognized at Merapi Volcano. Their mechanisms are poorly understood but MPs have been temporally associated with lava dome growth. We conducted a seismic experiment in January-February 1998, using four broadband seismographs to investigate the nature of seismic activity associated with dome growth. During our experiment, Merapi experienced mild dome growth with low-level seismic activity. We compare our data to that recorded on a local short-period (SP) network, with the following preliminary results. MP and LF events as recorded and classified on the short-period network instruments were recognized on the broadband network. Frequency spectrograms revealed similar patterns in the near summit region at widely separated broadband stations. Higher frequency spectra than previously recognized were identified for both MP and LF events, and were strongly attenuated as a function of radial distance from the source. Thus the spectral characteristics of these events as recorded on far-field stations are not fully indicative of the source processes. In particular, many events classified as LF-type appear to have much high frequency energy near the source. This aspect of these so-called LF earthquakes, and their association with very-long-period (VLP) pulses, suggests that many events identified in the far-field as LF events are in actuality a variety of the MP event and involve similar source processes. Broadband records indicated that simple large-amplitude VLP pulses were embedded in MP and LF wavetrains. From event to event these pulses were similar in their waveforms and had periods of 4 s. VLP events embedded in LF and MP earthquakes were located using particle motions. The epicenters were clustered in a central region of the dome complex, and preliminary source depths were within about 100 m of

  6. School Characteristics and Experiences of African American, Hispanic/Latino, and Native American Youth in Rural Communities: Relation to Educational Aspirations

    ERIC Educational Resources Information Center

    Irvin, Matthew J.; Byun, Soo-yong; Meece, Judith L.; Reed, Karla S.; Farmer, Thomas W.

    2016-01-01

    The primary purpose of this study was to examine differences in the school characteristics and experiences of African American, Hispanic/Latino, and Native American youth in rural high schools as well as their relation to educational aspirations. We also investigated the characteristics and experiences of students and their families given that…

  7. When Failing Doesn't Matter: A Narrative Inquiry into the Social Work Practice Learning Experiences of Black African Students in England

    ERIC Educational Resources Information Center

    Tedam, Prospera

    2014-01-01

    This paper reports the findings of a small-scale empirical study into the practice learning experiences of black African students of social work in England. Undertaken in the form of a pilot study, the findings reveal that practice learning experiences can be beneficial in enhancing skills and knowledge but can also cause distress, lower…

  8. Experiences and effects of psychiatric stigma: Monologues of the stigmatizers and the stigmatized in an African setting

    PubMed Central

    Egbe, Catherine O.

    2015-01-01

    People with mental illness (PWMI) are faced with a number of social and health-related challenges especially stigma and discrimination which tend to have negative effects on their lives. This paper presents narrative monologues portraying the experiences and effects of psychiatric stigma and discrimination on PWMI in South Africa. These narratives voice out the concerns of the stigmatizers (specifically family members and significant others of PWMI) and the stigmatized in a poetic fashion. The society is still not very sympathetic to the plights of PWMI and this affects their general health and well-being. Traditional beliefs and prejudice still drive public attitude towards PWMI especially in African settings. These narratives presented in a poetic fashion in this paper highlight some salient issues relating to the experience and effects of stigma and the desires of PWMI to be treated with love and respect and helped to lead healthy normal lives. PMID:26088367

  9. Experiences and effects of psychiatric stigma: Monologues of the stigmatizers and the stigmatized in an African setting.

    PubMed

    Egbe, Catherine O

    2015-01-01

    People with mental illness (PWMI) are faced with a number of social and health-related challenges especially stigma and discrimination which tend to have negative effects on their lives. This paper presents narrative monologues portraying the experiences and effects of psychiatric stigma and discrimination on PWMI in South Africa. These narratives voice out the concerns of the stigmatizers (specifically family members and significant others of PWMI) and the stigmatized in a poetic fashion. The society is still not very sympathetic to the plights of PWMI and this affects their general health and well-being. Traditional beliefs and prejudice still drive public attitude towards PWMI especially in African settings. These narratives presented in a poetic fashion in this paper highlight some salient issues relating to the experience and effects of stigma and the desires of PWMI to be treated with love and respect and helped to lead healthy normal lives. PMID:26088367

  10. Effect of the surface roughness on the seismic signal generated by a single rock impact: insight from laboratory experiments

    NASA Astrophysics Data System (ADS)

    Bachelet, Vincent; Mangeney, Anne; de Rosny, Julien; Toussaint, Renaud

    2016-04-01

    The seismic signal generated by rockfalls, landslides or avalanches is a unique tool to detect, characterize and monitor gravitational flow activity, with strong implication in terms of natural hazard monitoring. Indeed, as natural flows travel down the slope, they apply stresses on the ground, generating seismic waves in a wide frequency band. Our ultimate objective is to relate the granular flow properties to the generated signals that result from the different physical processes involved. We investigate here the more simple process: the impact of a single bead on a rough surface. Farin et al. [2015] have already shown theoretically and experimentally the existence of a link between the properties of an impacting bead (mass and velocity) on smooth surfaces, and the emitted signal (radiated elastic energy and mean frequency). This demonstrates that the single impactor properties can be deduced from the form of the emitted signal. We extend this work here by investigating the impact of single beads and gravels on rough and erodible surfaces. Experimentally, we drop glass and steel beads of diameters from 2 mm to 10 mm on a PMMA plate. The roughness of this last is obtained by gluing 3mm-diameter glass beads on one of its face. Free beads have been also added to get erodible beds. We track the dropped impactor motion, times between impacts and the generated acoustic waves using two fast cameras and 8 accelerometers. Cameras are used in addition to estimate the impactor rotation. We investigate the energy balance during the impact process, especially how the energy restitution varies as a function of the energy lost through acoustic waves. From these experiments, we clearly observe that even if more dissipative processes are involved (friction, grain reorganization, etc.), the single bead scaling laws obtained on smooth surfaces remain valid. A main result of this work is to quantify the fluctuations of the characteristic quantities such as the bounce angle, the

  11. Magmatic underplating and crustal growth in the Emeishan Large Igneous Province, SW China, revealed by a passive seismic experiment

    NASA Astrophysics Data System (ADS)

    Chen, Yun; Xu, Yigang; Xu, Tao; Si, Shaokun; Liang, Xiaofeng; Tian, Xiaobo; Deng, Yangfan; Chen, Lin; Wang, Peng; Xu, Yihe; Lan, Haiqiang; Xiao, Fuhui; Li, Wei; Zhang, Xi; Yuan, Xiaohui; Badal, José; Teng, Jiwen

    2015-12-01

    In an attempt to characterize the subsurface structure that is related to fossil mantle plume activity, a comprehensive geophysical investigation was conducted in the Emeishan Large Igneous Province (ELIP). The nature and geometry of the crust were examined within the scheme of the domal structure of ELIP, which comprises the Inner, Intermediate and Outer zones, which are defined on the basis of the biostratigraphy of pre-volcanic sediments. The bulk crustal properties within the Inner Zone are characterized by high density, high P-wave velocity, high Vp/Vs ratios and large crustal thickness. A visible continuous seismic converter is present in the upper part of the crust in the whole Intermediate Zone and the eastern part of the Inner Zone, but it is absent in the Inner Zone, where another seismic converter is observed in the lower part of the crust. The geometric configuration of these converters is attributable to the addition of mantle-derived melts to the pre-existing crust and subsequent interaction between them. The crustal geometry, which is delineated by the migrated image of receiver functions from the passive seismic experiment, and the crustal properties collectively suggest that a mafic layer of 15-20 km thickness and 150-180 km width exists at the base of the crust in the Inner Zone. Such a mafic layer reflects a vertical crustal growth through magmatic underplating at the base of the crust and intraplating within the upper crust. The salient spatial correlation between the deep crustal structure and the dome strongly supports a genetic link between crustal thickening and plume activity, if the pre-volcanic domal uplift is generated by the Permian Emeishan mantle plume. This arrangement is further supported by the consistency of the extent of crustal uplift estimated by isostatic equilibrium modeling and sedimentary data. This study therefore characterizes and provides evidence for a plume-modified crust in a large igneous province.

  12. Drawing the line: how African, Caribbean and White British women live out psychologically abusive experiences.

    PubMed

    Rivas, Carol; Kelly, Moira; Feder, Gene

    2013-09-01

    This study explores how African, Caribbean and White British women worked to hide psychological partner abuse as they experienced it, "do gender," and appear competent in social roles. They prioritized negotiated competencies as "good partners," actively setting socially and culturally embedded boundaries to their abuser's behaviors: an inner boundary encompassing normal behaviors and an outer one of "acceptable" behaviors projected as normal through remedial work. Behaviors breaching the outer boundary (e.g., if the women narrowed the bounds of the "acceptable") compromised the women's competence. This sometimes led them to actively use support services. Appropriate advice and support may change the boundaries. PMID:24142953

  13. Understanding the Breast Cancer Experience of Survivors: a Qualitative Study of African American Women in Rural Eastern North Carolina.

    PubMed

    Torres, Essie; Dixon, Crystal; Richman, Alice R

    2016-03-01

    The purpose of this study is to gain an in-depth understanding of African American breast cancer survivors' experiences, barriers and facilitators in accessing breast cancer treatment, and challenges in adherence to follow-up care. We conducted seven focus groups with 32 African American women with breast cancer in three rural counties in eastern North Carolina during August-November 2013. Surveys were also utilized to gather basic demographic and breast health history information. Thematic analysis was performed using the immersion crystallization approach. Several common areas of life affected by breast cancer included faith and support networks, psychosocial well-being, and quality of care issues. Faith in God was an important coping mechanism essential to all women in the study and a critical facilitator in survivorship. Support networks consisted of family, church-family, friends, and co-workers. The concept of fear included the discovery of breast cancer and fear of death, negative side effects of treatment, and social stigma of having breast cancer. Factors that influenced provider-patient relationship were age of provider, perceived lack of empathy, and providers leaving during treatment. Participants also expressed their lack of knowledge regarding a number of the side effects they were experiencing during and after their treatment. Results of this study contribute to the assessment of potential coping mechanisms used by African American breast cancer survivors (i.e., spirituality, positive attitudes, and support networks) that can potentially be effective and have a positive impact on the adjustment of life for survivors. PMID:25877467

  14. Diagnosing GCM errors over West Africa using relaxation experiments. Part II: intraseasonal variability and African easterly waves

    NASA Astrophysics Data System (ADS)

    Pohl, Benjamin; Douville, Hervé

    2011-10-01

    A near-global grid-point nudging of the Arpege-Climat atmospheric General Circulation Model towards ECMWF reanalyses is used to diagnose the regional versus remote origin of the summer model biases and variability over West Africa. First part of this study revealed a limited impact on the monsoon climatology compared to a control experiment without nudging, but a significant improvement of interannual variability, although the amplitude of the seasonal anomalies remained underestimated. Focus is given here on intraseasonal variability of monsoon rainfall and dynamics. The reproducible part of these signals is investigated through 30-member ensemble experiments computed for the 1994 rainy season, a year abnormally wet over the Sahel but representative of the model systematic biases. In the control experiment, Arpege-Climat simulates too few rainy days that are associated with too low rainfall amounts over the central and western Sahel, in line with the seasonal dry biases. Nudging the model outside Africa tends to slightly increase the number of rainy days over the Sahel, but has little effect on associated rainfall amounts. However, results do indicate that a significant part of the monsoon intraseasonal variability simulated by Arpege-Climat is controlled by lateral boundary conditions. Parts of the wet/dry spells over the Sahel occur in phase in the 30 members of the nudging experiment, and are therefore embedded in larger-scale variability patterns. Inter-member spread is however not constant across the selected summer season. It is partly controlled by African Easterly Waves, which show dissimilar amplitude from one member to another, but a coherent phasing in all members. A lowpass filtering of the nudging fields suggests that low frequency variations in the lateral boundary conditions can lead to eastward extensions of the African Easterly Jet, creating a favorable environment for easterly waves, while high frequency perturbations seem to control their

  15. Results of high resolution seismic imaging experiments for defining permeable pathways in fractured gas reservoirs

    SciTech Connect

    Majer, E.L.; Peterson, J.E.; Daley, T.

    1997-10-01

    As part of its Department of Energy (DOE) Industry cooperative program in oil and gas, Berkeley Lab has an ongoing effort in cooperation with Industry partners to develop equipment, field techniques, and interpretational methods to further the practice of characterizing fractured heterogeneous reservoirs. The goal of this work is to demonstrate the combined use of state-of-the-art technology in fluid flow modeling and geophysical imaging into an interdisciplinary approach for predicting the behavior of heterogeneous fractured gas reservoirs. The efforts in this program have mainly focused on using seismic methods linked with geologic and reservoir engineering analysis for the detection and characterization of fracture systems in tight gas formations, i.e., where and how to detect the fractures, what are the characteristics of the fractures, and how the fractures interact with the natural stresses, lithology, and their effect on reservoir performance. The project has also integrated advanced reservoir engineering methods for analyzing flow in fractured systems such that reservoir management strategies can be optimized. The work at Berkeley Lab focuses on integrating high resolution seismic imaging, (VSP, crosswell, and single well imaging), geologic information and well test data to invert for flow paths in fractured systems.

  16. Local-scale cross-correlation of seismic noise from the Calico fault experiment

    NASA Astrophysics Data System (ADS)

    Zhang, Jian; Gerstoft, Peter

    2014-06-01

    Most studies of seismic noise cross-correlation (NCC) have focused on regional/continental scale imaging using empirical surface-wave Green's functions extracted from primary (0.05-0.08 Hz) and secondary (0.1-0.16 Hz) microseisms. In this work, we present the NCC results at higher frequencies (>0.5 Hz) from 6 months seismic noise recorded by a local array (~4 km aperture) deployed along the Calico fault in the Mojave Desert, California. Both fast and slow propagating waves are observed from the NCC record-sections. We compare the NCCs from sensor pairs that share a common sensor with the records of a borehole shot located very close to this common sensor. The result shows a good match of the slow surface-wave arrivals, indicating that the NCC method is able to recover unbiased surface-wave Green's functions at local scales. The strong body-wave NCC component is caused by the P waves generated offshore California. Along a SW-NE profile across the fault, we observe apparent P-wave arrivals and their reflections, which can be explained by a low-velocity-zone (LVZ) along the Calico fault. We calculate the LVZ width to be ~ 2.3 km, and the P-wave velocity reduction within the LVZ to be ~35 %. These estimates are consistent with other evidence for a relatively wide LVZ along the Calico fault.

  17. The CAFE experiment: A joint seismic and MT investigation of the Cascadia subduction system

    NASA Astrophysics Data System (ADS)

    McGary, R. Shane

    In this thesis we present results from inversion of data using dense arrays of ˙ collocated seismic and magnetotelluric stations located in the Cascadia subduction zone region of central Washington. In the migrated seismic section, we clearly image the top of the slab and oceanic Moho, as well as a velocity increase corresponding to the eclogitization of the hydrated upper crust. A deeper velocity increase is interpreted as the eclogitization of metastable gabbros, assisted by fluids released from the dehydration of upper mantle chlorite. A low velocity feature interpreted as a fluid/melt phase is present above this transition. The serpentinized wedge and continental Moho are also imaged. The magnetotelluric image further constrains the fluid/melt features, showing a rising conductive feature that forms a column up to a conductor indicative of a magma chamber feeding Mt. Rainier. This feature also explains the disruption of the continental Moho found in the migrated image. Exploration of the assumption of smoothness implicit in the standard MT inversion provides tools that enable us to generate a more accurate MT model. This final MT model clearly demonstrates the link between slab derived fluids/melting and the Mt. Rainier magma chamber. (Copies available exclusively from MIT Libraries, libraries.mit.edu/docs - docs mit.edu)

  18. Termination of the Batholiths marine seismic experiment: the scientific method loses to hearsay

    NASA Astrophysics Data System (ADS)

    Hollister, L. S.

    2007-12-01

    The marine seismic component of the NSF-Continental Dynamics funded project Batholiths was terminated by Canadian authorities due to environmental concerns. Socioeconomic benefits of the project were not taken into account, nor were findings by the National Research Council on effects of ocean noise on marine mammal populations. The marine seismic component of Batholiths was to have been done using sound from airguns towed behind the R/V Langseth in order to seismically image the geologic structures below the Coast Mountains of British Columbia. The project was nearly identical in timing, location, and scope to the ACCRETE project, which was successfully permitted and done in the early fall of 1994, with no detected or known damage to the environment. However, what changed in the last 13 years was a dramatic increase of concern by eNGOs (environmental non- government organizations) that airguns produced sound that might be harmful to marine species, marine mammals in particular. The marine noise concerns were amplified by eNGO agendas and campaigns to prevent oil exploration along continental margins and to shut down naval exercises involving sonar to detect submarines. Compared to these agendas, Batholiths was an easy target because the PIs (Principal Investigators) did not have the manpower or financial or legal resources (in contrast to the Navy and oil companies) to push back against an organized campaign set on stopping Batholiths. The main concern used to mobilize public opinion against Batholiths was that, if we were permitted, then oil exploration in the nearby region would be permitted; and, if oil were found, drilling would proceed: the slippery slope argument. Thus, by stopping Batholiths with the speculation that airgun noise, as used in a marine seismic study, might damage marine life, the eNGOs believe they have stopped oil exploration in British Columbia coastal waters. It is widely recognized that everything was done right to get the permits for

  19. Successfully Educating Our African-American Students

    ERIC Educational Resources Information Center

    Moncree-Moffett, Kareem

    2013-01-01

    The purpose of this empirical study was to explore the lived experiences of African American retired female teachers who have prior experience with educating urban African American students in public schools. Also explored are the experiences of active African American female teachers of urban African American students and comparisons are…

  20. Use of active source geophones for passive source imaging: Examples from Bighorn Arch Seismic Experiment (BASE), USA

    NASA Astrophysics Data System (ADS)

    Sheehan, A.; O'rourke, C. T.; Haines, S. S.; Yang, Z.; Worthington, L. L.; Miller, K. C.

    2013-05-01

    In this paper we explore the variety of active and passive source deep seismic imaging that can be performed using continous wavefield recordings from a dense array of industry-style geophones. The data in this study were acquired during the 2009-10 EarthScope FlexArray Bighorn Arch Seismic Experiment(BASE) in central Wyoming, USA. In addition to traditional active and passive source seismic data acquisition, BASE included a deployment of 850 Reftek RT125 " Texan" dataloggers that produced continuous recording over 14 days. Ground motion was recorded via Geospace GS-11 4.5 Hz single channel vertical component geophones. The geophones were deployed in a grid of three E-W lines and two N-S lines across the Bighorn Mountains. We find that the high frequency geophones effectively record the P waves of teleseismic earthquakes. During the 15 days of continuous recording we observed 57 teleseismic events with pickable P-wave arrivals across the array, providing over 10,000 travel times (P, PKiKP, Pdiff, Pn) suitable for teleseismic tomography. The full waveforms can be used to extract additional information about the subsurface. We have successfully utilized teleseismic receiver-side crustal reverberation phases as virtual sources to mimic crustal reflection profiles (Yang et al., 2012). After depth conversion, we find a coherent phase that correlates well with the top of the Madison Formation under the Powder River and Bighorn Basins that flank the Bighorn Mountains. In addition, we combine the phases PpPdp from single-channel geophone recordings and Ps from three-component recordings to constrain the average Vp /Vs ratio for the sedimentary strata. Following Haines (2011), we are exploring the use of interferometric processing of active source blasts. In principle, virtual source and receiver gathers can be created through cross-correlation of full wavefields. The seismic interferometry provides a means of simulating alternative acquisition geometries, and has the

  1. Calibration formulae and values for velocity seismometers used in the 1998 Santa Clara Valley, California seismic experiment

    USGS Publications Warehouse

    Lindh, Allan G.; Eaton, Jerry P.; O'Neill Allen, Mary; Healy, John H.; Stewart, Samuel W.; Damerell, Lu

    1999-01-01

    Eaton (1975), Bakun and Dratler (1976), Eaton (1977), Healy and O’Neil (1977), Asten (1977), Stewart and O'Neill (1980), Liu and Peselnick (1986), Eaton (1991), Rodgers et al. (1995), and many others (see Asten (1977) for a list of earlier references) have presented formulae for calculating the damped generator constant (or motor constant), and the damping constant (or fractional damping ratio) for magnetically damped velocity seismometers. Unfortunately the notation varies between authors, and not all the formulae allow for some of the significant variables -- differences in input impedance of the recording system in particular. This has become particularly relevant because the USGS seismic networks in California have traditionally set up their velocity sensors for the 10K Ohm impedance of the standard USGS analog telemetry systems (Eaton, 1977), but modern digital recording systems are usually set up with high input impedances, often of a megaohm or greater. Thus the nominal calibration values valid for USGS velocity sensors in their “normal” configuration are incorrect when they are recorded on other systems. In this short note we have collected the relevant formulae needed, and computed the seismometer responses for the various velocity sensors used in the recent Santa Clara Valley Seismic Experiment (SCVSE, see Lindh et al., 1999).

  2. "Are You Sure You Know What You Are Doing?"--The Lived Experiences of an African American Male Kindergarten Teacher

    ERIC Educational Resources Information Center

    Bryan, Nathaniel; Browder, Jamison K.

    2013-01-01

    As of 2012, data indicate that only one percent of public school teachers are African American males. Numerous reports urge decision makers and higher education professionals to aggressively recruit and retain African American males as teachers in an effort to improve the academic outcomes of African American children in our educational system…

  3. Seismoelectric experiments in a natural laboratory: investigating the permeability/frequency dependence of co-seismic effects at the Boise Hydrogeophysical Research Site

    NASA Astrophysics Data System (ADS)

    Butler, K. E.; West, M. T.; Barrash, W.; Hinz, E. A.

    2009-12-01

    The propagation of seismic waves through porous media generates electric fields, known as seismoelectric effects, as a consequence of electrokinetic coupling associated with movement of pore fluid relative to the solid matrix. Seismoelectric conversions generated at interfaces are of interest for their predicted sensitivity to contrasts in permeability, and pore fluid type (among other properties) although they can be very challenging to measure. Stronger, co-seismic electric fields that travel within P-waves and Stoneley waves are easier to measure and may prove useful as tools for borehole logging or investigation of lateral variations in near surface sediments. In August, 2009, we carried out seismoelectric field experiments on the surface and in boreholes penetrating an unconfined, coarse-grained sand, gravel and cobble aquifer at the Boise Hydrogeophysical Research Site. The aquifer is composed of a sequence of 4 cobble-dominated units overlain by a sand channel and underlain, at a depth of approximately 20 m, by a layer of clay. The water table was located at a depth of approximately 2 m. The main objective of our experiments was to determine whether theoretical seismic/seismoelectric transfer functions, linking various physical properties to the amplitudes of co-seismic effects associated with P-waves, would be consistent with in-situ measurements made in a well-characterized natural environment. Identifying the roles of porosity and permeability was of particular interest given that theoretical models suggest (somewhat counter-intuitively) that the co-seismic effect is dependent on the former but not the latter at frequencies below Biot’s critical frequency - estimated to lie in the range of a few hundred to a few thousand Hz at this site. Borehole experiments utilized sledgehammer and weight drop seismic sources positioned on surface, 2 - 3 m away from the borehole collar. A downhole electrode array and downhole geophone were used (separately) to measure

  4. Theoretical and practical considerations for the design of the iMUSH active-source seismic experiment

    NASA Astrophysics Data System (ADS)

    Kiser, E.; Levander, A.; Harder, S. H.; Abers, G. A.; Creager, K. C.; Vidale, J. E.; Moran, S. C.; Malone, S. D.

    2013-12-01

    The multi-disciplinary imaging of Magma Under St. Helens (iMUSH) experiment seeks to understand the details of the magmatic system that feeds Mount St. Helens using active- and passive-source seismic, magnetotelluric, and petrologic data. The active-source seismic component of this experiment will take place in the summer of 2014 utilizing all of the 2600 PASSCAL 'Texan' Reftek instruments which will record twenty-four 1000-2000 lb shots distributed around the Mount St. Helens region. The instruments will be deployed as two consecutive refraction profiles centered on the volcano, and a series of areal arrays. The actual number of areal arrays, as well as their locations, will depend strongly on the length of the experiment (3-4 weeks), the number of instrument deployers (50-60), and the time it will take per deployment given the available road network. The current work shows how we are balancing these practical considerations against theoretical experiment designs in order to achieve the proposed scientific goals with the available resources. One of the main goals of the active-source seismic experiment is to image the magmatic system down to the Moho (35-40 km). Calculating sensitivity kernels for multiple shot/receiver offsets shows that direct P waves should be sensitive to Moho depths at offsets of 150 km, and therefore this will likely be the length of the refraction profiles. Another primary objective of the experiment is to estimate the locations and volumes of different magma accumulation zones beneath the volcano using the areal arrays. With this in mind, the optimal locations of these arrays, as well as their associated shots, are estimated using an eigenvalue analysis of the approximate Hessian for each possible experiment design. This analysis seeks to minimize the number of small eigenvalues of the approximate Hessian that would amplify the propagation of data noise into regions of interest in the model space, such as the likely locations of magma

  5. "She Told Them, Oh That Bitch Got AIDS": Experiences of Multilevel HIV/AIDS-Related Stigma Among African American Women Living with HIV/AIDS in the South.

    PubMed

    Fletcher, Faith; Ingram, Lucy Annang; Kerr, Jelani; Buchberg, Meredith; Bogdan-Lovis, Libby; Philpott-Jones, Sean

    2016-07-01

    African American women bear a disproportionate burden of HIV/AIDS in the United States. Although they constitute only 13% of the US population, African Americans account for nearly 65% of all new HIV infections among American women. In addition, this population suffers comparatively greater adverse health outcomes related to HIV status. African American women living with HIV in the South may be further burdened by HIV/AIDS stigma, which is comparatively more pronounced in this region. To further explore this burden, we used narrative data and the Social Ecological Model to explore how African American women living with HIV in the US South recount, conceptualize, and cope with HIV/AIDS stigma at interpersonal, community, and institutional levels. Our narrative analysis suggests that HIV-positive African American women living in the South are vulnerable to experiences of multilevel HIV stigma in various settings and contexts across multiple domains of life. Stigma subsequently complicated disclosure decisions and made it difficult for women to feel supported in particular social, professional and medical settings that are generally regarded as safe spaces for noninfected individuals. Findings suggest that the debilitating and compounded effect of multilevel HIV/AIDS stigma on HIV-positive African American women in the South warrants closer examination to tailor approaches that effectively address the unique needs of this population. PMID:27410498

  6. The experiences of African-American students majoring in engineering: Cognitive, non-cognitive and situational aspects

    NASA Astrophysics Data System (ADS)

    Hill, Gloria Pinckney

    1997-12-01

    To understand the causes for the disproportionately high rate of attrition among ethnic minority students, it is important to consider not only how they differ from the majority population, but what differences exist in personal qualities and academic preparation within groups at particular types of institutions, and within particular majors. The purpose of this study is to examine the experiences of African-American students enrolled in engineering at a predominately white, selective research university to determine which cognitive, non-cognitive and situational variables impact their progress towards graduation. The goal was to see how African-American students who meet or exceed the minimum criteria for admission perceive their experience on campus, and what strategies they use to manage their day-to-day existence. The study was conducted using personal interviews guided by an open-ended questionnaire. The qualitative methodology allowed students to assess the college experience through their own cultural lens, and to identify the cognitive, non-cognitive, and situational variables important to them. Responses were sorted by class and gender, tabulated and grouped into categories. Interpretation was primarily descriptive. Consistencies, inconsistencies, patterns and relationships to concepts in the literature and to the research questions were discussed. Findings indicate that well prepared students become less confident about their commitment to engineering and their ability to succeed academically after they begin matriculating rather than before, and that redefinition of what it means to be academically successful is an effective coping mechanism to sustain the effort required to master courses. The study suggests that the current focus on the impact of the freshman year transition on student retention should be expanded to include the sophomore year. This is particularly true for institutions where engineering students spend the first year in a core

  7. Simulation of complete seismic surveys for evaluation of experiment design and processing

    SciTech Connect

    Oezdenvar, T.; McMechan, G.A.; Chaney, P.

    1996-03-01

    Synthesis of complete seismic survey data sets allows analysis and optimization of all stages in an acquisition/processing sequence. The characteristics of available survey designs, parameter choices, and processing algorithms may be evaluated prior to field acquisition to produce a composite system in which all stages have compatible performance; this maximizes the cost effectiveness for a given level of accuracy, or for targets with specific characteristics. Data sets synthesized for three salt structures provide representative comparisons of time and depth migration, post-stack and prestack processing, and illustrate effects of varying recording aperture and shot spacing, iterative focusing analysis, and the interaction of migration algorithms with recording aperture. A final example demonstrates successful simulation of both 2-D acquisition and processing of a real data line over a salt pod in the Gulf of Mexico.

  8. The Tectonic Evolution of SE Canada: Seismic Evidence from the QM-III Experiment

    NASA Astrophysics Data System (ADS)

    Bastow, I. D.; Boyce, A.; Darbyshire, F. A.; Levin, V. L.; Menke, W. H.; Ellwood, A.

    2014-12-01

    Much of the geological record can be interpreted in the context of processes operating today at plate boundaries. This works well to explain processes and products during the Phanerozoic era; during Precambrian times when the oldest rocks were forming, however, conditions on the younger, hotter, more ductile Earth were likely very different, making analogies with modern day tectonics less certain. Gathering evidence preserved deep within the plates in the shields is thus essential to improve our understanding of the early Earth. Shields are usually underlain by thick, seismically fast roots that are absent beneath younger portions of Earth's surface. The thermochemically distinct nature of cratonic roots is often associated with Archean processes such as the extraction of komatiitic magmas. However, the cratonic core of North America does not fit easily into this Archean formation paradigm: part of the Canadian shield extends beneath the Archean Superior craton, but much of it persists beneath younger Proterozoic crust as well. We present here a relative arrival-time tomographic study of mantle seismic structure using data from a new seismograph network operating in SE Canada. Our stations extend from the Archean Superior craton around the southern tip of Hudson Bay, through Proterozoic Grenville terranes, and into Paleozoic coastal Maine and Nova Scotia. Tomographic images display three broad zones of mantle wavespeed: slow in the Appalachian terranes; fast in the Grenville Province; very fast within the Superior craton. Archean lithosphere has been modified by the Great Meteor hotspot, but we find no evidence for major plate-scale underthrusting during the Grenville orogeny. The abrupt wavespeed transition from Archean to Proterozoic mantle is thus consistent with the emerging consensus that keels form in two stages: a chemically depleted layer in Archean times followed by the thermal development of a less-depleted lithosphere during Proterozoic times.

  9. West African monsoon decadal variability and surface-related forcings: second West African Monsoon Modeling and Evaluation Project Experiment (WAMME II)

    NASA Astrophysics Data System (ADS)

    Xue, Yongkang; De Sales, Fernando; Lau, William K.-M.; Boone, Aaron; Kim, Kyu-Myong; Mechoso, Carlos R.; Wang, Guiling; Kucharski, Fred; Schiro, Kathleen; Hosaka, Masahiro; Li, Suosuo; Druyan, Leonard M.; Sanda, Ibrah Seidou; Thiaw, Wassila; Zeng, Ning; Comer, Ruth E.; Lim, Young-Kwon; Mahanama, Sarith; Song, Guoqiong; Gu, Yu; Hagos, Samson M.; Chin, Mian; Schubert, Siegfried; Dirmeyer, Paul; Ruby Leung, L.; Kalnay, Eugenia; Kitoh, Akio; Lu, Cheng-Hsuan; Mahowald, Natalie M.; Zhang, Zhengqiu

    2016-06-01

    The second West African Monsoon Modeling and Evaluation Project Experiment (WAMME II) is designed to improve understanding of the possible roles and feedbacks of sea surface temperature (SST), land use land cover change (LULCC), and aerosols forcings in the Sahel climate system at seasonal to decadal scales. The project's strategy is to apply prescribed observationally based anomaly forcing, i.e., "idealized but realistic" forcing, in simulations by climate models. The goal is to assess these forcings' effects in producing/amplifying seasonal and decadal climate variability in the Sahel between the 1950s and the 1980s, which is selected to characterize the great drought period of the last century. This is the first multi-model experiment specifically designed to simultaneously evaluate such relative contributions. The WAMME II models have consistently demonstrated that SST forcing is a major contributor to the twentieth century Sahel drought. Under the influence of the maximum possible SST forcing, the ensemble mean of WAMME II models can produce up to 60 % of the precipitation difference during the period. The present paper also addresses the role of SSTs in triggering and maintaining the Sahel drought. In this regard, the consensus of WAMME II models is that both Indian and Pacific Ocean SSTs greatly contributed to the drought, with the former producing an anomalous displacement of the Intertropical Convergence Zone before the WAM onset, and the latter mainly contributes to the summer WAM drought. The WAMME II models also show that the impact of LULCC forcing on the Sahel climate system is weaker than that of SST forcing, but still of first order magnitude. According to the results, under LULCC forcing the ensemble mean of WAMME II models can produces about 40 % of the precipitation difference between the 1980s and the 1950s. The role of land surface processes in responding to and amplifying the drought is also identified. The results suggest that catastrophic

  10. Strike-slip fault Kinematics and mechanics at the seismic cycle time-scale : Results from new analogue model experiments.

    NASA Astrophysics Data System (ADS)

    Caniven, Yannick; Dominguez, Stéphane; Soliva, Roger; Cattin, Rodolphe; Peyret, Michel; Chéry, Jean; Romano, Christian

    2013-04-01

    The average seismic cycle duration extends from hundred to a few thousands years but geodetic measurements, including trilateration, GPS, Insar and seismological data extend over less than one century. This short time observation scale renders difficult, then, to constrain the role of key parameters such as fault friction and geometry, crust rheology, stress and strain rate that control the kinematics and mechanics of active faults. To solve this time scale issue, we have developed a new experimental set-up that reproduces scaled micro-earthquakes and several hundreds of seismic cycles along a strike-slip fault. The model is constituted by two polyurethane foam plates laterally in contact, lying on a basal silicone layer, which simulate the mechanical behaviour of an elastoplastic upper crust over a ductile lower crust, respectively. To simulate the boundary conditions of a strike-slip fault, a computerized motoreductor system moves the two compartments on an opposite sens and at a constant very low velocity (a few µm/s). The model spatial and temporal scaling, deduces from analog material physical and mechanical parameters, implies that 1 cm in the model represents 2-3 km in the nature and 1 s is equivalent to 5-15 years. Surface-horizontal strain field is quantified by sub-pixel correlation of digital camera pictures recorded every 16 µm of displacement. For each experience about 2000 horizontal-velocity field measurements are recorded. The analysis of model-interseismic and coseismic surface displacements and their comparison to seismogenic natural faults demonstrate that our analog model reproduces correctly both near and far-field surface strains. To compare the experiences, we have developed several algorithms that allow studying the main spatial and temporal evolution of the physical parameters and surface deformation processes that characterise the seismic cycle (magnitudes, stress, strain, friction coefficients, interseismic locking depth, recurrence

  11. Surviving oppression under the Rock: The intersection of New York’s drug, welfare, and educational polices in the lived experiences of low-income African-Americans

    PubMed Central

    Windsor, Liliane Cambraia; Dunlap, Eloise; Armour, Marilyn

    2012-01-01

    Drawing on standpoint and intersectionality theories, this study explores the degree to which interactions among New York State’s Rockefeller Drug Laws, educational and welfare policies have contributed to the maintenance of a culture of surveillance in which the lives of impoverished African Americans are overseen and influenced by oppressive policies and governmental institutions. Qualitative secondary analysis of longitudinal ethnographic data was conducted. Findings demonstrate multiple disadvantages that impoverished African American families struggling with substance use and/or sale experience. These disadvantages accumulated intergenerationally, in a snowball effect making it difficult for participants to maintain stable lives. Findings explored the tension between participants’ experiences with oppression and the multiple ways they either assimilated or resisted their oppression. New sensitive policies informed by standpoint, intersectionality, and Afrocentric perspectives must be developed to increase the availability of meaningful employment and strengthening impoverished African American communities. PMID:23216440

  12. Good fit or chilly climate: An exploration of the persistence experiences of African-American women graduates of predominantly White college science programs

    NASA Astrophysics Data System (ADS)

    Justin-Johnson, Carolyn

    This qualitative study explored the persistence experiences of African-American women science graduates of a predominantly White institution (PWI). The purpose of the study was to promote a holistic understanding---complementing findings from quantitative studies---of how African-American women give meaning to their collegiate experiences. Eight recent graduates of two college science programs (biological sciences and chemistry) were selected to participate in the study because of their willingness to answer interview questions related to sensitive issues about their experiences. Data analysis included coding transcripts, creating a codebook, memo writing, and constructing a model single-case event-flow network and a conceptually clustered matrix. Participants in the study shared a common viewpoint about the unwelcoming and non-supportive environment that they navigated to persist to graduation. Specifically, they identified a combination of (1) non-supportive mechanisms that could have been deterrents to their persistence and (2) supportive mechanisms that were instrumental in helping them to cope with negative experiences on campus that made them feel "uncomfortable" and alienated as one of the few African-American women in science classes. Findings in this study suggest that it is imperative for predominantly White institutions to organize reform efforts around creating more welcoming and inclusive campus environments, especially in the sciences, for African-American women---thus promoting satisfying college experiences that lead to degree and career attainment.

  13. Seismic hazard assessment of the Kivu rift segment based on a new sismo-tectonic zonation model (Western Branch of the East African Rift system)

    NASA Astrophysics Data System (ADS)

    Havenith, Hans-Balder; Delvaux, Damien

    2015-04-01

    In the frame of the Belgian GeoRisCA multi-risk assessment project focused on the Kivu and Northern Tanganyika Region, a seismic hazard map has been produced for this area. It is based on a on a recently re-compiled catalogue using various local and global earthquake catalogues. The use of macroseismic epicenters determined from felt earthquakes allowed to extend the time-range back to the beginning of the 20th century, thus spanning about 100 years. The magnitudes have been homogenized to Mw and the coherence of the catalogue has been checked and validated. The seismo-tectonic zonation includes 10 seismic source areas that have been defined on the basis of the regional geological structure, neotectonic fault systems, basin architecture and distribution of earthquake epicenters. The seismic catalogue was filtered by removing obvious aftershocks and Gutenberg-Richter Laws were determined for each zone. On the basis of this seismo-tectonic information and existing attenuation laws that had been established by Twesigomwe (1997) and Mavonga et al. (2007) for this area, seismic hazard has been computed with the Crisis 2012 (Ordaz et al., 2012) software. The outputs of this assessment clearly show higher PGA values (for 475 years return period) along the Rift than the previous estimates by Twesigomwe (1997) and Mavonga (2007) while the same attenuation laws had been used. The main reason for these higher PGA values is likely to be related to the more detailed zonation of the Rift structure marked by a strong gradient of the seismicity from outside the rift zone to the inside. Mavonga, T. (2007). An estimate of the attenuation relationship for the strong ground motion in the Kivu Province, Western Rift Valley of Africa. Physics of the Earth and Planetary Interiors 62, 13-21. Ordaz M, Martinelli F, Aguilar A, Arboleda J, Meletti C, D'Amico V. (2012). CRISIS 2012, Program for computing seismic hazard. Instituto de Ingeniería, Universidad Nacional Autónoma de M

  14. An in-situ stimulation experiment in crystalline rock - assessment of induced seismicity levels during stimulation and related hazard for nearby infrastructure

    NASA Astrophysics Data System (ADS)

    Gischig, Valentin; Broccardo, Marco; Amann, Florian; Jalali, Mohammadreza; Esposito, Simona; Krietsch, Hannes; Doetsch, Joseph; Madonna, Claudio; Wiemer, Stefan; Loew, Simon; Giardini, Domenico

    2016-04-01

    A decameter in-situ stimulation experiment is currently being performed at the Grimsel Test Site in Switzerland by the Swiss Competence Center for Energy Research - Supply of Electricity (SCCER-SoE). The underground research laboratory lies in crystalline rock at a depth of 480 m, and exhibits well-documented geology that is presenting some analogies with the crystalline basement targeted for the exploitation of deep geothermal energy resources in Switzerland. The goal is to perform a series of stimulation experiments spanning from hydraulic fracturing to controlled fault-slip experiments in an experimental volume approximately 30 m in diameter. The experiments will contribute to a better understanding of hydro-mechanical phenomena and induced seismicity associated with high-pressure fluid injections. Comprehensive monitoring during stimulation will include observation of injection rate and pressure, pressure propagation in the reservoir, permeability enhancement, 3D dislocation along the faults, rock mass deformation near the fault zone, as well as micro-seismicity. The experimental volume is surrounded by other in-situ experiments (at 50 to 500 m distance) and by infrastructure of the local hydropower company (at ~100 m to several kilometres distance). Although it is generally agreed among stakeholders related to the experiments that levels of induced seismicity may be low given the small total injection volumes of less than 1 m3, detailed analysis of the potential impact of the stimulation on other experiments and surrounding infrastructure is essential to ensure operational safety. In this contribution, we present a procedure how induced seismic hazard can be estimated for an experimental situation that is untypical for injection-induced seismicity in terms of injection volumes, injection depths and proximity to affected objects. Both, deterministic and probabilistic methods are employed to estimate that maximum possible and the maximum expected induced

  15. The experiences and coping strategies of United Kingdom-based African women following an HIV diagnosis during pregnancy.

    PubMed

    Treisman, Karen; Jones, Fergal W; Shaw, Elizabeth

    2014-01-01

    A qualitative investigation was conducted to explore the experience of African women living in the United Kingdom after being diagnosed with HIV during pregnancy. Participants (N = 12) completed a demographic questionnaire and participated in one-to-one semi-structured interviews. The interview addressed multiple personal, interpersonal, and systemic issues related to HIV, as well as HIV in the context of motherhood. Data were analyzed using interpretative phenomenological analysis. Themes that emerged included: (a) HIV being part of one's wider tapestry, (b) community and systemic influences and responses to HIV, (c) experiencing a different story of HIV, and (d) the mother-child relationship. Strikingly, the aspect of HIV these women reported finding most distressing was their inability to breastfeed, which seemed central to their cultural identity as mothers. Clinical recommendations and implications are made. PMID:23523367

  16. Undergraduate African American females in the sciences: A qualitative study of student experiences affecting academic success and persistence

    NASA Astrophysics Data System (ADS)

    Essien-Wood, Idara R.

    Given the lack of literature on Undergraduate African American females in the sciences (UAAFS), this study sought to explicate their experiences at one large, predominantly White, Research I institution in the southwestern United States. In particular, the purpose of this study was to identify factors that affect the academic success and persistence of Black females in the natural and physical sciences. Data was collected via in-depth, semi-structured interviews with 15 Black female science majors. Findings from this study identified several supportive mechanisms for academic success: family, religion, teaching assistants and friends. Also identified were seven barriers to academic success: employment, lack of diversity, cultural dissonance, unwelcoming Research I environment, faculty, advisors, classmates, and lab groups. Further, an analysis of students' responses revealed numerous instances of racial and gender micro-aggressions. Recommendations are provided to address factors identified as affecting student academic success and persistence as well as a culture of micro-aggressive behavior.

  17. Traditional Healing, Biomedicine and the Treatment of HIV/AIDS: Contrasting South African and Native American Experiences

    PubMed Central

    Flint, Adrian

    2015-01-01

    Traditional healing remains an important aspect of many people’s engagement with healthcare and, in this, responses to the treatment of HIV/AIDS are no different. However, given the gravity of the global HIV/AIDS pandemic, there has been much debate as to the value of traditional healing in this respect. Accordingly, this paper explores the extent to which meaningful accommodation between the biomedical and traditional sectors is possible (and/or even desirable). It does this through a consideration of Native American and South African experiences, looking at how the respective groups, in which medical pluralism is common, have addressed the issue of HIV/AIDS. The paper points to the importance of developing “culturally appropriate” forms of treatment that emphasise complementary rather than adversarial engagement between the traditional and biomedical systems and how policymakers can best facilitate this. PMID:25903057

  18. The experience of the Antarctic Seismic Data Library System (SDLS) as a hub for researchers in antarctic crustal studies.

    NASA Astrophysics Data System (ADS)

    Diviacco, Paolo; Wardell, Nigel

    2010-05-01

    The SDLS was created in April 1991 under the auspices of the Scientific Committee on Antarctic Research to provide open access to Antarctic multichannel seismic-reflection data (MCS) for use in cooperative research projects. The SDLS operates under the mandates of the Antarctic Treaty System, by which all institutions that collect MCS data in Antarctica must submit their MCS data to the SDLS. The SDLS has library branches worldwide at which researchers may view and study the MCS data. MCS data are submitted to the SDLS within 4 years of collection and remain in the library under SDLS guidelines until 8 years after collection. Thereafter, the data go to World Data Centers or equivalents for unrestricted use. The SDLS offers a clearing house, based at Istituto Nazionale di Oceanografia e di Geofisica Sperimentale (OGS) where data are processed when needed and georeferenced, so that the end user can be provided with usable, although basic, post-stack seismic sections. Re-processing of data is beyond the scope of the SDLS, so that if a researcher is interested in reviewing pre-stack data he/she must resort to the data owner. So far 228,000 km of seismic data have been made public in all sectors of the Antarctic region. To augment the concept of physical repositories where data can be accessed by researchers travelling to one of the branches or from where data could be copied to digital media and sent to users, in 2003 it was decided to develop a web interface where data could be searched for and accessed directly. At that moment no previous non-commercial experience was available in this data field, so that the system was designed from scratch. Several technologies were introduced, tested, and after a period of use, reviewed and tuned. Particular attention was devoted to the seismic data viewing facility, which was tailored to the needs of a community with specific practices and legacies. Seismic data are sensitive data that are very important for the E&P industry, so

  19. Seismic velocity structure and spatial distribution of reflection intensity off the Boso Peninsula, Central Japan, revealed by an ocean bottom seismographic experiment

    NASA Astrophysics Data System (ADS)

    Kono, Akihiro; Sato, Toshinori; Shinohara, Masanao; Mochizuki, Kimihiro; Yamada, Tomoaki; Uehira, Kenji; Shinbo, Takashi; Machida, Yuuya; Hino, Ryota; Azuma, Ryosuke

    2016-04-01

    Off the Boso Peninsula, central Japan, where the Sagami Trough is in the south and the Japan Trench is in the east, there is a triple junction where the Pacific plate (PAC), the Philippine Sea plate (PHS) and the Honshu island arc (HIA) meet each other. In this region, the PAC subducts beneath the PHS and the HIA, and the PHS subducts beneath the HIA. Due to the subduction of 2 oceanic plates, numerous seismic events took place in the past. In order to understand these events, it is important to image structure of these plates. Hence, many researchers attempted to reveal the substructure from natural earthquakes and seismic experiments. Because most of the seismometers are placed inland area and the regular seismicity off Boso is inactive, it is difficult to reveal the precise substructure off Boso area using only natural earthquakes. Although several marine seismic experiments using active sources were conducted, vast area remains unclear off Boso Peninsula. In order to improve the situation, a marine seismic experiment, using airgun as an active source, was conducted from 30th July to 4th of August, 2009. The survey line has 216 km length and 20 Ocean Bottom Seismometers (OBSs) were placed on it. We estimated 2-D P-wave velocity structure from the airgun data using the PMDM (Progressive Model Development Method; Sato and Kenett, 2000) and the FAST (First Arrival Seismic Tomography ; Zelt and Barton, 1998). Furthermore, we identified the probable reflection phases from the data and estimated the location of reflectors using Travel time mapping method (Fujie et al. 2006). We found some reflection phases from the data, and the reflectors are located near the region where P-wave velocity is 5.0 km/s. We interpret that the reflectors indicate the plate boundary between the PHS and the HIA. The variation of the intensity of reflection along the upper surface of PHS seems to be consistent with the result from previous reflection seismic experiment conducted by Kimura et

  20. "We're Here Because We're Black": The Schooling Experiences of French-Speaking African-Canadian Students with Refugee Backgrounds

    ERIC Educational Resources Information Center

    Schroeter, Sara; James, Carl E.

    2015-01-01

    This article discusses the educational experiences of a group of French-speaking Black African-born students who entered Canada as refugees. They were attending a French school and were placed in a separate programme that was designed to meet their particular needs given their limited language skills and level of education. Drawing on critical…

  1. Low-Income African-American Caregivers' Experiences of Being Referred to Mental Health Services by the School Counselor: Implications for Best Practices

    ERIC Educational Resources Information Center

    Tucker, Catherine

    2009-01-01

    Referring students for mental health care is a core job function for school counselors, and one that is often stressful for all parties involved. In this phenomenological study, six low-income African-American caregivers were interviewed about their experiences of having a son or grandson referred for mental health care by the school counselor.…

  2. The Role of Race, Racism and Power in the Experiences and Perspectives of African American Males in the Context of Their Ascendence to the Superintendency

    ERIC Educational Resources Information Center

    George, Hughes B.

    2011-01-01

    Using the lens of Critical Race Theory, I present the experiences and perspectives of African American male superintendents in the context of their ascension to the superintendency. Participants in the study are chief executive officers of a school district. The primary question of this study is what are the contributing factors, particularly the…

  3. Life Experiences of People Who Stutter, and the Perceived Impact of Stuttering on Quality of Life: Personal Accounts of South African Individuals

    ERIC Educational Resources Information Center

    Klompas, Michelle; Ross, Eleanor

    2004-01-01

    The purpose of the study was to investigate the life experiences of a group of South African adults who stutter and the impact of stuttering on their quality of life. Participants were 16 adults with a mean age of 28.9 and ranging from 20 to 59 years. Methods involved individual interviews designed to explore the life domains of education; social…

  4. The Everyday Mathematical Experiences and Understandings of Three, 4-Year-Old, African-American Children from Working-Class Backgrounds

    ERIC Educational Resources Information Center

    Benigno, Grace Marie R.

    2012-01-01

    This qualitative study examined the everyday mathematical experiences and understandings of three, 4-year-old, African-American children from working-class backgrounds. The study drew on Street, Baker, and Tomlin's (2005) broad, ideological model of mathematics as "social" and their analytic concepts of mathematical events (units of…

  5. Calculation and experiment for dynamic response of bridge in deep water under seismic excitation

    NASA Astrophysics Data System (ADS)

    Liu, Chun-guang; Sun, Guo-shuai

    2014-08-01

    The fluid-structure interaction under seismic excitation is very complicated, and thus the damage identification of the bridge in deep water is the key technique to ensure the safe service. Based on nonlinear Morison equation considering the added mass effect and the fluid-structure interaction effect, the effect of hydrodynamic pressure on the structure is analyzed. A series of underwater shaking table tests are conducted in the air and in water. The dynamic characteristics affected by hydrodynamic pressure are discussed and the distribution of hydrodynamic pressure is also analyzed. In addition, the damage of structure is distinguished through the natural frequency and the difference of modal curvature, and is then compared with the test results. The numerical simulation and test of this study indicate that the effect of hydrodynamic pressure on the structure should not be neglected. It is also found that the presence of the damage, the location of the damage and the degree of the severity can be judged through the variation of structure frequency and the difference of modal curvature.

  6. Rapid population growth and fragile environments: the sub-Saharan African and south Asian experience.

    PubMed

    Caldwell, J C; Caldwell, P

    1994-02-18

    Case studies of the world's two poorest regions, sub-Saharan Africa and South Asia, were used to illustrate the compromised standard of living of the poor and environmental damage due to continued rapid population growth. The conclusion was that the livelihoods of the poor should not be endangered for preserving the living standards of richer people. Nations must not ignore the challenges of reducing population growth as fast as can be achieved. The transitional period over the next 50 years is the main concern, because population growth rates will be slowing. Rural population growth is expected to decline from 60% of total population growth in South Asia to 7% between 2000 and 2025; similarly the decline in sub-Saharan Africa would be from 50% to 15%. Over the past 30 years, food production in South Asia has kept pace with population growth. Sub-Saharan Africa has adopted food importation to meet demand. African problems are a low resource base, faster population growth, and the fact that governments and individuals are too poor to maintain soil fertility. Long-term studies of how much soil depletion will occur are not available for these regions, and local area studies are not as pessimistic. Transition policies are needed to put "people first in terms of engineered or directed population and ecological change." The six main issues are the following: 1) the Brundtland Commission appropriately identified poverty as the main cause and effect of environmental degradation because of the threat to survival; 2) the verdict is still out about whether food production will keep pace with population growth through economic growth and investment in agriculture; 3) empirical research is needed to examine local social and regulatory institutions and the possibility of reinforcing these mechanisms rather than instituting central controls; 4) central coercion or modernizing economic policies can destroy local level controls; 5) famine is a complex ecological phenomenon and the

  7. Lithospheric structure beneath Central Europe from the POLONAISE'97, CELEBRATION 2000, ALP 2002, and SUDETES 2003 seismic refraction experiments

    NASA Astrophysics Data System (ADS)

    Guterch, A.; Grad, M.; Keller, G. R.

    2005-12-01

    Beginning in 1997, Central Europe between the Baltic and Adriatic Seas, has been covered by an unprecedented network of seismic refraction experiments POLONAISE'97, CELEBRATION 2000, ALP 2002, and SUDETES 2003, have only been possible due to a massive international consortium consisted of more than 30 institutions from 16 countries in Europe and North America. The majority of recording instruments was provided by the IRIS/PASSCAL Instrument Center and the University of Texas at El Paso (USA), and several other countries also provided instrumentation. Total length of seismic profiles in all experiments is about 20,000 km. The main results of these experiments are: 1) the delineation of the deep structure of the southwestern margin of the East European Craton (southern Baltica) and its relationship to younger terranes; delineation of the major terranes and crustal blocks in the Trans European Suture Zone; determination of the structural framework of the Pannonian basin; elucidation of the deep structure and evolution of the Western Carpathian Mountains and Eastern Alps; determination of the structural relationships between the structural elements of the Bohemian massif and adjacent features; construction of 3-D models of the lithospheric structure; and evaluation and develop geodynamic models for the tectonic evolution of the region. Experiment Working Groups Members: K. Aric, M. Behm, E. Brueckl, W. Chwatal, H. Grassl, S. Hock, V. Hoeck, F. Kohlbeck, E.-M. Rumpfhuber, Ch. Schmid, R. Schmoller, C. Tomek, Ch. Ullrich, F.Weber (Austria), A.A. Belinsky (Belarus), I. Asudeh, R. Clowes, Z. Hajnal (Canada), F. Sumanova (Croatia), M. Broz , P. Hrubcova, M. Korn, O. Karousova, J. Malek, A. Spicak (Czech Republic), S.L. Jensen, P. Joergensen, H. Thybo (Denmark), K. Komminaho, U. Luosto, T. Tiira, J. Yliniemi (Finland), F. Bleibinhaus, R. Brinkmann, B. Forkmann, H. Gebrande, H. Geissler, A. Hemmann, G. Jentzsch, D. Kracke, A. Schulze, K. Schuster (Germany), T. Bodoky, T

  8. The Grenville Front Tectonic Zone: Results from the 1986 Great Lakes Onshore Seismic Wide-Angle Reflection and Refraction Experiment

    NASA Astrophysics Data System (ADS)

    Epili, Duryodhan; Mereu, Robert F.

    1991-09-01

    The Grenville Front, which marks the orogenic boundary between the Archean Superior Structural Province and the much younger Grenville Province to the southeast, is one of the major tectonic features of the Canadian Shield. Within Canada, it is approximately 1900 km in length extending from the north shore of Lake Huron across Ontario and Quebec to Labrador. In 1986, a major coincident onship near-vertical reflection and onshore wide-angle reflection/refraction experiment (GLIMPCE-Great Lakes International Multidisciplinary Program on Crustal Evolution) was conducted along a series of lines across the Great lakes. One of the lines, line J, ran across Georgian Bay and Lake Huron for a distance of 350 km and crossed the Grenville Front Tectonic Zone (GFTZ). The seismic signals from the air gun array source were well recorded by the onshore stations up to distances of 250 km with a seismic trace spacing of 50-62.5 m. The GFTZ had a profound effect on the nature of the reflector patterns observed on the onshore seismic sections. Data recorded by the stations on the east end of the line indicate that the crustal P phases are very complex and form a "shinglelike" pattern of reflected waves. Data recorded by stations at the center and at the western end of the line show that the Pg phases are normal and lack the shinglelike appearance. This character of arrivals was also observed on the corresponding S wave sections. A combined P and S wave forward modeling analysis shows that the GFTZ is composed of bands of reflectors dipping at angles of 20°-35° extending to the lower crust. These reflectors were also well imaged on the coincident near-vertical reflection data. Reflectors under the Britt domain to the east of the GFTZ have a shallower dip than those along the zone. The structure of the crust under the Manitoulin terrane to the west of the GFTZ is laterally homogeneous with a major intracrustal reflector at a depth of 17-20 km below the surface. Poisson's ratio is

  9. The Subjective Experience of Social Class and Upward Mobility Among African American Men in Graduate School

    PubMed Central

    Sánchez, Francisco J.; Liu, William Ming; Leathers, Leslie; Goins, Joyce; Vilain, Eric

    2011-01-01

    We used Consensual Qualitative Research Methodology to analyze responses from 14 African American men (MdnAge = 25 years-old) in graduate school at a predominantly-White university in the Midwestern region of the United Sates regarding how they acquired awareness of their social-class status; how social class was related to their sense of masculinity; how social class was related to race and skin tone; and the role that education and a romantic partner could play in upward mobility. School peers were the main source for their early awareness of social class. Many believed that discrimination maintains social class stratification that disadvantages racial minorities and that one's race will always trump any personal characteristics—including having light-complected skin and an advanced degree. Finally many overcame several obstacles during their educational career, and most believed that a romantic relationship with a woman from a privileged background could facilitate upward mobility. Psychological scientists and practitioners are encouraged to consider the role that social class plays when examining men's well-being. PMID:22058659

  10. Factors affecting student success in a first-year mathematics course: a South African experience

    NASA Astrophysics Data System (ADS)

    Kizito, Rita; Munyakazi, Justin; Basuayi, Clement

    2016-01-01

    In spite of sustained efforts tertiary institutions implement to try and improve student academic performance, the number of students succeeding in first-year mathematics courses remains disturbingly low. For most students, the gap between their mathematical capability and the competencies they are expected and need to develop to function effectively in these courses persists even after course instruction. In this study, an instrument for identifying and examining factors affecting student performance and success in a first-year Mathematics university course was developed and administered to 86 students. The overall Cronbach's Alpha coefficient for the questionnaire was found to be 0.916. Having identified variables from prior research known to affect student performance, factor analysis was used to identify variables exhibiting the greatest impact on student performance. The variables included prior academic knowledge, workload, student approaches to learning, assessment, student support teaching quality, methods and resources. From the analysis, students' perceptions of their workload emerged as the factor having the greatest impact on student's performance, followed by the matriculation examination score. The findings are discussed and strategies that can be used to improve teaching and contribute to student success in a first-year mathematics course in a South African context are presented.

  11. Do experiences of racial discrimination predict cardiovascular disease among African American Men? The moderating role of internalized negative racial group attitudes

    PubMed Central

    Lincoln, Karen D; Adler, Nancy E; Syme, S. Leonard

    2010-01-01

    Studies examining associations between racial discrimination and cardiovascular health outcomes have been inconsistent, with some studies finding the highest risk of hypertension among African Americans who report no discrimination. A potential explanation of the latter is that hypertension and other cardiovascular problems are fostered by internalization and denial of racial discrimination. To explore this hypothesis, the current study examines the role of internalized negative racial group attitudes in linking experiences of racial discrimination and history of cardiovascular disease among African American men. We predicted a significant interaction between reported discrimination and internalized negative racial group attitudes in predicting cardiovascular disease. Weighted logistic regression analyses were conducted among 1216 African American men from the National Survey of American Life (NSAL; 2001– 2003). We found no main effect of racial discrimination in predicting history of cardiovascular disease. However, agreeing with negative beliefs about Blacks was positively associated with cardiovascular disease history, and also moderated the effect of racial discrimination. Reporting racial discrimination was associated with higher risk of cardiovascular disease among African American men who disagreed with negative beliefs about Blacks. However, among African American men who endorsed negative beliefs about Blacks, the risk of cardiovascular disease was greatest among those reporting no discrimination. Findings suggest that racial discrimination and the internalization of negative racial group attitudes are both risk factors for cardiovascular disease among African American men. Furthermore, the combination of internalizing negative beliefs about Blacks and the absence of reported racial discrimination appear to be associated with particularly poor cardiovascular health. Steps to address racial discrimination as well as programs aimed at developing a positive

  12. Amplitude and phase normalization of seismograms from multiple seismograph recording systems for the Yellowstone-Snake River Plain seismic refraction experiment

    SciTech Connect

    Baker, M.R.; Braile, L.W.; Smith, R.B.

    1982-04-10

    A z transform filter theory method for the normalization of the instrument responses of several seismographs is presented. In this method, an inverse filter is derived by consideration of the seismometer/recorder characteristics which may be applied to a given seismogram to convert the system frequency response to that of a reference system. Inverse filters are derived for the seismographs used on the 1978 Yellowstone-Snake River Plain seismic profiling experiment. It is shown by application to these data that the inverse filters are effective in amplitude normalization and that their use allows improvement in the amplitude and waveform character of seismic record sections.

  13. P-wave velocity structure of the southern Ryukyu margin east of Taiwan: Results from the ACTS wide-angle seismic experiment

    NASA Astrophysics Data System (ADS)

    Klingelhoefer, F.; Berthet, T.; Lallemand, S.; Schnurle, P.; Lee, C.-S.; Liu, C.-S.; McIntosh, K.; Theunissen, T.

    2012-11-01

    An active seismic experiment has been conducted across the southern Ryukyu margin east of Taiwan over the whole trench-arc-backarc system in May 2009. Twenty-four ocean bottom seismometers (OBS) were deployed from the Ryukyu trench to the southern Okinawa trough over the Ryukyu arc and forearc. Wide angle seismic data were recorded by the OBS array while coincident reflection seismic data were acquired using a 6 km long streamer and a 6600 cubic inch seismic airgun array. Results from tomographic inversion of 21091 travel time picks along this line allowed us to image crustal structures of the Ryukyu margin down to a depth of 25 km. The transect has been designed to provide a better seismic velocity structure of the subduction zone in a highly deformed area that has produced an M8 earthquake in 1920. The line crosses a seismic cluster of earthquakes which source mechanisms are still poorly understood. The subducting oceanic crust of the Huatung Basin is about 5-6 km thick. The underlying mantle exhibits low seismic velocities around 7.8 km/s suggesting some hydrothermal alterations or alteration of the upper mantle through faults generated by the flexure of the subducting plate as it enters the subduction. Low velocities, up to 4.5 km/s, associated with the accretionary wedge are well imaged from the trench back to the Nanao forearc. A major result concerns the abrupt termination of the buttress at the rear of the accretionary wedge. Despite the low resolution of the tomographic inversion near the subduction interface, several lines of evidence supporting the presence of a low velocity zone beneath the toe of the forearc buttress could be established. The Moho beneath the Ryukyu non-volcanic arc is located at a depth around 25 km depth.

  14. Lower crustal deformation beneath the central Transverse Ranges, southern California: Results from the Los Angeles Region Seismic Experiment

    USGS Publications Warehouse

    Godfrey, N.J.; Fuis, G.S.; Langenheim, V.; Okaya, D.A.

    2002-01-01

    We present a P wave velocity model derived from active source seismic data collected during the 1994 Los Angeles Region Seismic Experiment. Our model extends previously published upper crustal velocity models to mantle depths. Our model was developed by both ray tracing through a layered model and calculating travel times through a gridded model. It includes an 8-km-thick crustal root centered beneath the surface trace of the San Andreas fault, north of the highest topography in the San Gabriel Mountains. A simple mass balance calculation suggests that ???36 km of north-south shortening across the San Andreas fault in the central Transverse Ranges could have formed this root. If north-south compression began when the "Big Bend" in the San Andreas fault formed at ???5 Ma, 36 km of shortening implies a north-south contraction rate of ???7.1 mm/yr across the central Transverse Ranges. If, instead, north-south compression began when the Transverse Ranges formed at 3.4-3.9 Ma, 36 km of shortening implies a contraction rate of 9.2-10.6 mm/yr. North of the San Andreas fault, the Mojave Desert crust has a low-velocity (6.3 km/s) mid and lower crust and a 28-km-deep Moho. South of the San Andreas fault, beneath the Los Angeles and San Gabriel Valley basins, there is a fast (6.6-6.8 km/s), thick (10-12 km) lower crust with a 27-km-deep Moho. Farther south still, the lower crust of the Continental Borderland is fast (6.6-6.8 km/s) and thin (5 km) with a shallow (22 km deep) Moho.

  15. Overview of the Dust and Biomass-burning Experiment and African Monsoon Multidisciplinary Analysis Special Observing Period-0

    NASA Astrophysics Data System (ADS)

    Haywood, J. M.; Pelon, J.; Formenti, P.; Bharmal, N.; Brooks, M.; Capes, G.; Chazette, P.; Chou, C.; Christopher, S.; Coe, H.; Cuesta, J.; Derimian, Y.; Desboeufs, K.; Greed, G.; Harrison, M.; Heese, B.; Highwood, E. J.; Johnson, B.; Mallet, M.; Marticorena, B.; Marsham, J.; Milton, S.; Myhre, G.; Osborne, S. R.; Parker, D. J.; Rajot, J.-L.; Schulz, M.; Slingo, A.; Tanré, D.; Tulet, P.

    2008-12-01

    The African Monsoon Multidisciplinary Analysis (AMMA) is a major international campaign investigating far-reaching aspects of the African monsoon, climate and the hydrological cycle. A special observing period was established for the dry season (SOP0) with a focus on aerosol and radiation measurements. SOP0 took place during January and February 2006 and involved several ground-based measurement sites across west Africa. These were augmented by aircraft measurements made by the Facility for Airborne Atmospheric Measurements (FAAM) aircraft during the Dust and Biomass-burning Experiment (DABEX), measurements from an ultralight aircraft, and dedicated modeling efforts. We provide an overview of these measurement and modeling studies together with an analysis of the meteorological conditions that determined the aerosol transport and link the results together to provide a balanced synthesis. The biomass burning aerosol was significantly more absorbing than that measured in other areas and, unlike industrial areas, the ratio of excess carbon monoxide to organic carbon was invariant, which may be owing to interaction between the organic carbon and mineral dust aerosol. The mineral dust aerosol in situ filter measurements close to Niamey reveals very little absorption, while other measurements and remote sensing inversions suggest significantly more absorption. The influence of both mineral dust and biomass burning aerosol on the radiation budget is significant throughout the period, implying that meteorological models should include their radiative effects for accurate weather forecasts and climate simulations. Generally, the operational meteorological models that simulate the production and transport of mineral dust show skill at lead times of 5 days or more. Climate models that need to accurately simulate the vertical profiles of both anthropogenic and natural aerosols to accurately represent the direct and indirect effects of aerosols appear to do a reasonable job

  16. Problem-dependent 3-d Inversion of P-wave Arrivals From Local Events Recorded During The Svekalapko Deep Seismic Experiment In Finland

    NASA Astrophysics Data System (ADS)

    Kozlovskaya, E.; Hjelt, S.-E.; Yliniemi, J.; Korhonen, J.; Elo, S.; Svekalapko Seismic Tomography Working Group

    The SVEKALAPKO temporary seismic array was originally designed for studying the lithospheric structure beneath the southern Finland by means of teleseismic events. In addition, the high quality recordings of local seismic events (earthquakes and quarry blasts) registered by the SVEKALAPKO array contain a lot of information about the structure of the upper lithosphere beneath the southern Finland. However, the traditional local event tomography of SVEKALAPKO data cannot result in the ve- locity model valid for proper geological interpretation. The main reasons for this is the lack of the space resolution, which results in strong non-uniqueness of the to- mographic inversion. This problem can be treated by introducing various kinds of a-priori information into the inversion algorithm. The a-priori information available for the SVEKALAPKO study area includes not only the information from previous control source seismic experiments, but also potential fields data and petrophysical data. Usage of such a non-homogeneous a-priori information required a problem- dependent algorithm of seismic data inversion, which was developed on the base of non-probabilistic uncertainty measures. An example of this algorithm application to SVEKALAPKO local seismic event data is presented.

  17. Unwanted sexual experiences among young men in four sub-Saharan African countries: prevalence and context.

    PubMed

    Moore, Ann M; Madise, Nyovani; Awusabo-Asare, Kofi

    2012-10-01

    Unwanted sexual experiences are most frequently examined from the woman's perspective, yet these experiences happen to men as well. Part of the reason for the paucity of studies on coerced sexual experiences among men is the difficulty in gathering information about such experiences. This study examines the prevalence of unwanted sexual experiences at sexual debut as well as ever among young men aged 12-19 years old in Burkina Faso, Ghana, Malawi and Uganda. The data come from nationally-representative surveys and in-depth interviews with approximately 50 young men in each country gathered around 2004. Between 4 and 12% of young men stated that they were 'not willing at all' at sexual debut and between 3 and 6% said that they had ever experienced unwanted sex. Narratives from in-depth interviews give insights into the context surrounding men's unwanted sexual experiences. The sometimes conflicting information provided by the respondents serve to confound rather than illuminate the contexts within which these unwanted sexual experiences occurred, demonstrating that coercion for young men looks extremely different than coercion for young women, spurring us to improve our measures of sexual coercion among men. PMID:22943657

  18. Results from the latest SN-4 multi-parametric benthic observatory experiment (MARsite EU project) in the Gulf of Izmit, Turkey: oceanographic, chemical and seismic monitoring

    NASA Astrophysics Data System (ADS)

    Embriaco, Davide; Marinaro, Giuditta; Frugoni, Francesco; Giovanetti, Gabriele; Monna, Stephen; Etiope, Giuseppe; Gasperini, Luca; Çağatay, Namık; Favali, Paolo

    2015-04-01

    An autonomous and long-term multiparametric benthic observatory (SN-4) was designed to study gas seepage and seismic energy release along the submerged segment of the North Anatolian Fault (NAF). Episodic gas seepage occurs at the seafloor in the Gulf of Izmit (Sea of Marmara, NW Turkey) along this submerged segment of the NAF, which ruptured during the 1999 Mw7.4 Izmit earthquake. The SN-4 observatory already operated in the Gulf of Izmit at the western end of the 1999 Izmit earthquake rupture for about one-year at 166 m water depth during the 2009-2010 experiment (EGU2014-13412-1, EGU General Assembly 2014). SN-4 was re-deployed in the same site for a new long term mission (September 2013 - April 2014) in the framework of MARsite (New Directions in Seismic Hazard assessment through Focused Earth Observation in the Marmara Supersite, http://marsite.eu/ ) EC project, which aims at evaluating seismic risk and managing of long-term monitoring activities in the Marmara Sea. A main scientific objective of the SN-4 experiment is to investigate the possible correlations between seafloor methane seepage and release of seismic energy. We used the same site of the 2009-2010 campaign to verify both the occurrence of previously observed phenomena and the reliability of results obtained in the previous experiment (Embriaco et al., 2014, doi:10.1093/gji/ggt436). In particular, we are interested in the detection of gas release at the seafloor, in the role played by oceanographic phenomena in this detection, and in the association of gas and seismic energy release. The scientific payload included, among other instruments, a three-component broad-band seismometer, and gas and oceanographic sensors. We present a technical description of the observatory, including the data acquisition and control system, results from the preliminary analysis of this new multidisciplinary data set, and a comparison with the previous experiment.

  19. Tackling the African “poverty trap”: The Ijebu-Ode experiment

    PubMed Central

    Mabogunje, Akin L.

    2007-01-01

    An experiment in poverty reduction began in 1998 in the city of Ijebu-Ode, Nigeria (estimated 1999 population 163,000), where, without the remittances from relatives abroad, an estimated 90% of the population lived below the poverty line of $1.00 (U.S.) per person per day. Central to the experiment was whether poverty can be dramatically reduced through a city consultation process that seeks to mobilize the entire community along with its diaspora. With 7 years of experience, the Ijebu-Ode experiment has been successful in many ways. There is increasing evidence that poverty in the city has been reduced significantly through the microfinancing of existing and new productive activities and the estimated >8,000 jobs these activities have created. Training based on both sustainability science and technology and indigenous practitioner knowledge has been a critical factor in the establishment of cooperatives and the development of new enterprises in specialty crops, small animal, and fish production. Much of this success has been possible as a result of harnessing social capital, especially through the dynamic leadership of the traditional authorities of the city and by the provision of ample loanable funds through the National Poverty Eradication Program of the federal government. The city consultation process itself engendered a participatory focus to the experiment from the beginning and has encouraged sustainabaility. Yet long-term sustainability is still in question as the initial leadership needs replacement, and credit, the heart of the experiment, lacks sufficient collateral. PMID:17942687

  20. Mining-Induced Stress Transfer and Its Relation to a {M}_w 1.9 Seismic Event in an Ultra-deep South African Gold Mine

    NASA Astrophysics Data System (ADS)

    Ziegler, Moritz; Reiter, Karsten; Heidbach, Oliver; Zang, Arno; Kwiatek, Grzegorz; Stromeyer, Dietrich; Dahm, Torsten; Dresen, Georg; Hofmann, Gerhard

    2015-10-01

    On 27 December 2007, a {M}_w 1.9 seismic event occurred within a dyke in the deep-level Mponeng Gold Mine, South Africa. From the seismological network of the mine and the one from the Japanese-German Underground Acoustic Emission Research in South Africa (JAGUARS) group, the hypocentral depth (3,509 m), focal mechanism and aftershock location were estimated. Since no mining activity took place in the days before the event, dynamic triggering due to blasting can be ruled out as the cause. To investigate the hypothesis that stress transfer, due to excavation of the gold reef, induced the event, we set up a small-scale (450× 300× 310{m}^3) high-resolution three-dimensional (3D) geomechanical numerical model. The model consisted of the four different rock units present in the mine: quartzite (footwall), hard lava (hanging wall), conglomerate (gold reef) and diorite (dykes). The numerical solution was computed using a finite-element method with a discretised mesh of approximately 10^6 elements. The initial stress state of the model is in agreement with in situ data from a neighbouring mine, and the step-wise excavation was simulated by mass removal from the gold reef. The resulting 3D stress tensor and its changes due to mining were analysed based on the Coulomb failure stress changes on the fault plane of the event. The results show that the seismic event was induced regardless of how the Coulomb failure stress changes were calculated and of the uncertainties in the fault plane solution. We also used the model to assess the seismic hazard due to the excavation towards the dyke. The resulting curve of stress changes shows a significant increase in the last {˜}50 {m} in front of the dyke, indicating that small changes in the mining progress towards the dyke have a substantial impact on the stress transfer.

  1. A Grounded Theory of the College Experiences of African American Males in Black Greek-Letter Organizations

    ERIC Educational Resources Information Center

    Ford, David Julius, Jr.

    2014-01-01

    Studies have shown that involvement in a student organization can improve the academic and psychosocial outcomes of African American male students (Harper, 2006b; Robertson & Mason, 2008; Williams & Justice, 2010). Further, Harper, Byars, and Jelke (2005) stated that African American fraternities and sororities (i.e., Black Greek-letter…

  2. Understanding the Relationships and Experiences That Contribute to African Americans' Decision to Enroll in Doctoral Education

    ERIC Educational Resources Information Center

    McCallum, Carmen Michelle

    2012-01-01

    African Americans have made great advancements in postsecondary education. Over the last thirty years, enrollment and degree attainment has increased over 65% at undergraduate and graduate degree levels (National Center for Education Statistics, 2008). Yet despite these gains, African Americans continue to severely trail behind other racial and…

  3. Experiences of Reentry and Nontraditional African American Women and Their Support Networks: A Journey in Pursuit of a College Degree

    ERIC Educational Resources Information Center

    Denson, Janet L.

    2010-01-01

    This research study reports the findings of how support networks impact the success of African American women in completing their college degree. A phenomenological research methodology of 10 African American women participants of in-depth face-to-face interviews was used to collect the data. Fifty percent of the women completed their degree and…

  4. Cultural Self Meets Cultural Other in the African American Experience: Teachers' Responses to a Curriculum Content Reform.

    ERIC Educational Resources Information Center

    Shujaa, Mwalimu J.

    1995-01-01

    Discusses certain complexities of personal transformation among people implementing African and African American curriculum content reform in the Buffalo (New York) public schools, highlighting individual teachers' understanding of and responses to the reform and noting that attitudes about their own and other people's ethnicity proved important…

  5. Exploring the Lived Experiences of African American and White Female Faculty toward Tenure-Granting and Promotion Processes

    ERIC Educational Resources Information Center

    Oliver, Ralphilia C.

    2010-01-01

    Purpose:The purpose of this study was to explore African American and White female faculty members' perceptions about tenure and promotion processes at research universities. As more women enter the ranks of academia, the difficulties encountered toward attainment of tenure continue to prevail, specifically for African American women. It is hoped…

  6. Religion and Spirituality in the Meaning-Making and Coping Experiences of African American Women: A Qualitative Analysis

    ERIC Educational Resources Information Center

    Mattis, Jacqueline S.

    2002-01-01

    This qualitative study examines the ways in which African American women use religion/spirituality to cope and to construct meaning in times of adversity. Content analysis of the narratives of a sample of African American women respondents (n = 23) revealed a set of eight nonoverlapping themes that explicate religiosity/spirituality's role in…

  7. The Black Body as a Counterspace: The Experiences of African American Students at a Predominantly White Institution

    ERIC Educational Resources Information Center

    Jones-Malone, Dionne LaShell

    2011-01-01

    This qualitative study examines the use of counterspaces by eight upperclassman African American students at a predominantly White institution. This study sought to identify how counterspaces were used by African American students and how those counterspaces foster a sense of belonging for students. Field observations and semi-structured, in-depth…

  8. Behind the Miracle: Emerging Insights from South African Business Leadership Experiences

    ERIC Educational Resources Information Center

    Lynham, Susan A.; Taylor, Robert K.; Dooley, Larry M.

    2005-01-01

    The decade preceding the end of apartheid in South Africa (SA) represents a period of remarkable national leadership, and atypical business leadership. Insights from these extraordinary business leadership experiences largely remain in the form of uncaptured oral histories. Yet they are inspiring stories of practices and principles of truly…

  9. Racial Ideological Beliefs and Racial Discrimination Experiences as Predictors of Academic Engagement among African American Adolescents

    ERIC Educational Resources Information Center

    Smalls, Ciara; White, Rhonda; Chavous, Tabbye; Sellers, Robert

    2007-01-01

    Adolescents' understandings of their social identities and related personal experiences influence their adaptations and responses within domains in which those identities are salient. The authors explore associations of racial identity beliefs regarding how Blacks should act, think, and behave (racial ideologies) and racial discrimination…

  10. Predicting Substance Use Behavior among South African Adolescents: The Role of Leisure Experiences across Time

    ERIC Educational Resources Information Center

    Sharp, Erin Hiley; Coffman, Donna L.; Caldwell, Linda L.; Smith, Edward A.; Wegner, Lisa; Vergnani, Tania; Mathews, Catherine

    2011-01-01

    Using seven waves of data, collected twice a year from the 8th through the 11th grades in a low-resource community in Cape Town, South Africa, we aimed to describe the developmental trends in three specific leisure experiences (leisure boredom, new leisure interests, and healthy leisure) and substance use (cigarettes, alcohol, and marijuana)…

  11. Experiences of forced sex among female patrons of alcohol-serving venues in a South African township

    PubMed Central

    Watt, Melissa H.; Sikkema, Kathleen J.; Abler, Laurie; Velloza, Jennifer; Eaton, Lisa A.; Kalichman, Seth C.; Skinner, Donald; Pieterse, Desiree

    2014-01-01

    South Africa has among the highest rates of forced sex worldwide, and alcohol use has consistently been associated with risk of forced sex in South Africa. However, methodological challenges impact the accuracy of forced sex measurements. This study explored the assessment of forced sex among South African women attending alcohol-serving venues and identified factors associated with reporting recent forced sex. Women (n=785) were recruited from 12 alcohol-serving venues in a peri-urban township in Cape Town. Brief self-administered surveys included questions about lifetime and recent experiences of forced sex. Surveys included a single question about forced sex and detailed questions about sex by physical force, threats, verbal persuasion, trickery, and spiked drinks. We first compared the single question about forced sex to a composite variable of forced sex as unwanted sex by physical force, threats or spiked drinks. We then examined potential predictors of recent forced sex (demographics, drinking behavior, relationship to the venue, abuse experiences). The single question about forced sex had low sensitivity (0.38); over half of the respondents who reported on the detailed questions that they had experienced forced sex by physical force, threats or spiked drinks reported on the single question item that they had not experienced forced sex. Using our composite variable, 18.6% of women reported lifetime and 10.8% reported recent experiences of forced sex. In our adjusted logistic regression model, recent forced sex using the composite variable was significantly associated with hazardous drinking (OR=1.92), living farther from the venue (OR=1.81), recent intimate partner violence (OR=2.53), and a history of childhood sexual abuse (OR=4.35). The findings support the need for additional work to refine the assessment of forced sex. Efforts to prevent forced sex should target alcohol-serving venues, where norms and behaviors may present particular risks for women who

  12. Experiences of forced sex among female patrons of alcohol-serving venues in a South African township.

    PubMed

    Watt, Melissa H; Sikkema, Kathleen J; Abler, Laurie; Velloza, Jennifer; Eaton, Lisa A; Kalichman, Seth C; Skinner, Donald; Pieterse, Desiree

    2015-05-01

    South Africa has among the highest rates of forced sex worldwide, and alcohol use has consistently been associated with risk of forced sex in South Africa. However, methodological challenges affect the accuracy of forced sex measurements. This study explored the assessment of forced sex among South African women attending alcohol-serving venues and identified factors associated with reporting recent forced sex. Women (n = 785) were recruited from 12 alcohol-serving venues in a peri-urban township in Cape Town. Brief self-administered surveys included questions about lifetime and recent experiences of forced sex. Surveys included a single question about forced sex and detailed questions about sex by physical force, threats, verbal persuasion, trickery, and spiked drinks. We first compared the single question about forced sex to a composite variable of forced sex as unwanted sex by physical force, threats, or spiked drinks. We then examined potential predictors of recent forced sex (demographics, drinking behavior, relationship to the venue, abuse experiences). The single question about forced sex had low sensitivity (0.38); more than half of the respondents who reported on the detailed questions that they had experienced forced sex by physical force, threats, or spiked drinks reported on the single question item that they had not experienced forced sex. Using our composite variable, 18.6% of women reported lifetime and 10.8% reported recent experiences of forced sex. In our adjusted logistic regression model, recent forced sex using the composite variable was significantly associated with hazardous drinking (OR = 1.92), living farther from the venue (OR = 1.81), recent intimate partner violence (OR = 2.53), and a history of childhood sexual abuse (OR = 4.35). The findings support the need for additional work to refine the assessment of forced sex. Efforts to prevent forced sex should target alcohol-serving venues, where norms and behaviors may present particular

  13. Using diaries to explore the work experiences of primary health care nursing managers in two South African provinces

    PubMed Central

    Munyewende, Pascalia O.; Rispel, Laetitia C.

    2014-01-01

    Background South Africa is on the brink of another wave of major health system reforms that underscore the centrality of primary health care (PHC). Nursing managers will play a critical role in these reforms. Objective The aim of the study was to explore the work experiences of PHC clinic nursing managers through the use of reflective diaries, a method hitherto under-utilised in health systems research in low- and middle-income countries. Design During 2012, a sub-set of 22 PHC nursing managers was selected randomly from a larger nurses’ survey in two South African provinces. After informed consent, participants were requested to keep individual diaries for a period of 6 weeks, using a clear set of diary entry guidelines. Reminders consisted of weekly short message service reminders and telephone calls. Diary entries were analysed using thematic content analysis. A diary feedback meeting was held with all the participants to validate the findings. Results Fifteen diaries were received, representing a 68% response rate. The majority of respondents (14/15) were female, each with between 5 and 15 years of nursing experience. Most participants made their diary entries at home. Diaries proved to be cathartic for individual nursing managers. Although inter-related and not mutually exclusive, the main themes that emerged from the diary analysis were health system deficiencies; human resource challenges; unsupportive management environment; leadership and governance; and the emotional impact of clinic management. Conclusions Diaries are an innovative method of capturing the work experiences of managers at the PHC level, as they allow for confidentiality and anonymity, often not possible with other qualitative research methods. The expressed concerns of nursing managers must be addressed to ensure the success of South Africa's health sector reforms, particularly at the PHC level. PMID:25537937

  14. Drinking before and after pregnancy recognition among South African women: the moderating role of traumatic experiences

    PubMed Central

    2014-01-01

    Background South Africa has one of the world’s highest rates of fetal alcohol spectrum disorder (FASD) and interpersonal trauma. These co-occurring public health problems raise the need to understand alcohol consumption among trauma-exposed pregnant women in this setting. Since a known predictor of drinking during pregnancy is drinking behavior before pregnancy, this study explored the relationship between women’s drinking levels before and after pregnancy recognition, and whether traumatic experiences – childhood abuse or recent intimate partner violence (IPV) – moderated this relationship. Methods Women with incident pregnancies (N = 66) were identified from a longitudinal cohort of 560 female drinkers in a township of Cape Town, South Africa. Participants were included if they reported no pregnancy at one assessment and then reported pregnancy four months later at the next assessment. Alcohol use was measured by the Alcohol Use Disorders Identification Test (AUDIT), and traumatic experiences of childhood abuse and recent IPV were also assessed. Hierarchical linear regressions controlling for race and age examined childhood abuse and recent IPV as moderators of the effect of pre-pregnancy recognition drinking on post-pregnancy recognition AUDIT scores. Results Following pregnancy recognition, 73% of women reported drinking at hazardous levels (AUDIT ≥ 8). Sixty-four percent reported early and/or recent exposure to trauma. While drinking levels before pregnancy significantly predicted drinking levels after pregnancy recognition, t(64) = 3.50, p < .01, this relationship was moderated by experiences of childhood abuse, B = -.577, t(60) = -2.58, p = .01, and recent IPV, B = -.477, t(60) = -2.16, p = .04. Pregnant women without traumatic experiences reported drinking at levels consistent with levels before pregnancy recognition. However, women with traumatic experiences tended to report elevated AUDIT scores following pregnancy recognition, even if low

  15. Notes on some experiments on the application of subtractive compensation to USGS seismic magnetic tape recording and playback systems

    USGS Publications Warehouse

    Eaton, Jerry P.

    1975-01-01

    The purpose of these experiments is to lay the groundwork for the implementation of subtractive compensation of the USGS seismic network tape playbacks utilizing the Develco model 6203 discriminators at a x1 playback speed. Although the Develco discriminators were designed for this application and a matching Develco compensation discriminator was purchased, effective use of this system for subtractive compensation has been blocked by the inadequate (frequency dependent) matching of the phase of the compensation signal to that of the data signal at the point compensation is carried out in the data discriminators. John Van Schaack has ameliorated the phase mismatch problem by an empirical alteration of the compensation discriminator input bandpass filter. We have selected a set (of eight) Develco discriminators and adjusted their compensation signal input levels to minimize spurious signals (noise) originating from tape speed irregularities. The sensitivity of the data discriminators was adjusted so that deviations of +125 Hz and -125 Hz produced output signals of +2.00 volts and -2.00 volts, respectively. The eight data discriminators are driven by a multiplex signal on a single tape track (subcarriers 680, 1020, 1360, 1700, 2040, 2380, 2720, and 3060 Hz). The Develco-supplied compensation discriminator requires an unmodulated 3125 Hz signal on a separate tape track.

  16. Crustal structure variations along the NW-African continental margin: a comparison of new and existing models from wide angle and reflection seismic data

    NASA Astrophysics Data System (ADS)

    Biari, Y.; Klingelhoefer, F.; Sahabi, M.; Aslanian, D.; Philippe, S.; Louden, K. E.; Berglar, K.; Moulin, M.; Mehdi, K.; Graindorge, D.; Evain, M.; Benabellouahed, M.; Reichert, C. J.

    2014-12-01

    Deep seismic data represent a key to understand the geometry and mechanism of continental rifting. The passive continental margin of NW-Africa is one of the oldest on earth, formed during the Upper Triassic-Lower Liassic rifting of the central Atlantic Ocean over 200 Ma. We present new and existing wide-angle and reflection seismic data from three study regions along the margin located in the North Moroccan salt basin, on the central continental margin offshore Safi and in the south, offshore Dakhla. In each of the study areas several combined wide-angle and reflection seismic profiles perpendicular and parallel to the margin have been acquired and forward modelled using comparable methods. The thickness of unthinned continental crust decreases from 36 km in the North to about 27 km in the South. In the North Moroccan Basin continental crust thins from originally 36 km to about 8 km in a 150 km wide zone. The basin itself is underlain by highly thinned continental crust. Offshore safi thinning of the continental crust is confined to a 130 km wide zone with no neighboring sedimentary basin underlain by continental crust. In both areas the zone of crustal thinning is characterised by the presence of large blocks and abundant salt diapirs. In the south crustal thinning is more rapid in a zone of 90 km and asymmetric with the upper crust thinning more closely to the continent than the lower crust, probably due to depth-dependent stretching and the presence of the precambrian Reguibat Ridge on land. Oceanic crust is characterised by a thickness of 7-8 km along the complete margin. Relatively high velocities of up to 7.5 km/s have been imaged between magnetic anomalies S1 and M25, and are probably related to changes in the spreading velocities at the time of the Kimmeridgian/Tithonian plate reorganisation. Volcanic activity seems to be confined to the region next to the Canary Islands, and is thus not related to the initial opening of the oceanic, which was related to no

  17. Building effective public-private partnerships: experiences and lessons from the African Comprehensive HIV/AIDS Partnerships (ACHAP).

    PubMed

    Ramiah, Ilavenil; Reich, Michael R

    2006-07-01

    This paper examines the processes for building highly collaborative public-private partnerships for public health, with a focus on the efforts to manage the complex relationships that underlie these partnerships. These processes are analyzed for the African Comprehensive HIV/AIDS Partnerships (ACHAP), a 5-year partnership (2001-2005) between the government of Botswana, Merck & Co., Inc. (and its company foundation), and the Bill & Melinda Gates Foundation. ACHAP is a highly collaborative initiative. The ACHAP office in Botswana engages intensively (on a daily basis) with the government of Botswana (an ACHAP partner and ACHAP's main grantee) to support HIV/AIDS control in that country, which had an adult prevalence of 38.5% HIV infection in 2000 when ACHAP was being established. The paper discusses the development of ACHAP in four stages: the creation of ACHAP, the first year, the second and third years, and the fourth year. Based on ACHAP's experiences over these four years, the paper identifies five lessons for managing relationships in highly collaborative public-private partnerships for public health. PMID:16487640

  18. Measuring conditions and trends in ecosystem services at multiple scales: the Southern African Millennium Ecosystem Assessment (SAfMA) experience.

    PubMed

    van Jaarsveld, A S; Biggs, R; Scholes, R J; Bohensky, E; Reyers, B; Lynam, T; Musvoto, C; Fabricius, C

    2005-02-28

    The Southern African Millennium Ecosystem Assessment (SAfMA) evaluated the relationships between ecosystem services and human well-being at multiple scales, ranging from local through to sub-continental. Trends in ecosystem services (fresh water, food, fuel-wood, cultural and biodiversity) over the period 1990-2000 were mixed across scales. Freshwater resources appear strained across the continent with large numbers of people not securing adequate supplies, especially of good quality water. This translates to high infant mortality patterns across the region. In some areas, the use of water resources for irrigated agriculture and urban-industrial expansion is taking place at considerable cost to the quality and quantity of freshwater available to ecosystems and for domestic use. Staple cereal production across the region has increased but was outstripped by population growth while protein malnutrition is on the rise. The much-anticipated wood-fuel crisis on the subcontinent has not materialized but some areas are experiencing shortages while numerous others remain vulnerable. Cultural benefits of biodiversity are considerable, though hard to quantify or track over time. Biodiversity resources remain at reasonable levels, but are declining faster than reflected in species extinction rates and appear highly sensitive to land-use decisions. The SAfMA sub-global assessment provided an opportunity to experiment with innovative ways to assess ecosystem services including the use of supply-demand surfaces, service sources and sink areas, priority areas for service provision, service 'hotspots' and trade-off assessments. PMID:15814355

  19. Measuring conditions and trends in ecosystem services at multiple scales: the Southern African Millennium Ecosystem Assessment (SAfMA) experience

    PubMed Central

    van Jaarsveld, A.S; Biggs, R; Scholes, R.J; Bohensky, E; Reyers, B; Lynam, T; Musvoto, C; Fabricius, C

    2005-01-01

    The Southern African Millennium Ecosystem Assessment (SAfMA) evaluated the relationships between ecosystem services and human well-being at multiple scales, ranging from local through to sub-continental. Trends in ecosystem services (fresh water, food, fuel-wood, cultural and biodiversity) over the period 1990–2000 were mixed across scales. Freshwater resources appear strained across the continent with large numbers of people not securing adequate supplies, especially of good quality water. This translates to high infant mortality patterns across the region. In some areas, the use of water resources for irrigated agriculture and urban–industrial expansion is taking place at considerable cost to the quality and quantity of freshwater available to ecosystems and for domestic use. Staple cereal production across the region has increased but was outstripped by population growth while protein malnutrition is on the rise. The much-anticipated wood-fuel crisis on the subcontinent has not materialized but some areas are experiencing shortages while numerous others remain vulnerable. Cultural benefits of biodiversity are considerable, though hard to quantify or track over time. Biodiversity resources remain at reasonable levels, but are declining faster than reflected in species extinction rates and appear highly sensitive to land-use decisions. The SAfMA sub-global assessment provided an opportunity to experiment with innovative ways to assess ecosystem services including the use of supply–demand surfaces, service sources and sink areas, priority areas for service provision, service ‘hotspots’ and trade-off assessments. PMID:15814355

  20. Effects of mammalian herbivore declines on plant communities: observations and experiments in an African savanna

    PubMed Central

    Young, Hillary S; McCauley, Douglas J; Helgen, Kristofer M; Goheen, Jacob R; Otárola-Castillo, Erik; Palmer, Todd M; Pringle, Robert M; Young, Truman P; Dirzo, Rodolfo

    2013-01-01

    1. Herbivores influence the structure and composition of terrestrial plant communities. However, responses of plant communities to herbivory are variable and depend on environmental conditions, herbivore identity and herbivore abundance. As anthropogenic impacts continue to drive large declines in wild herbivores, understanding the context dependence of herbivore impacts on plant communities becomes increasingly important. 2. Exclosure experiments are frequently used to assess how ecosystems reorganize in the face of large wild herbivore defaunation. Yet in many landscapes, declines in large wildlife are often accompanied by other anthropogenic activities, especially land conversion to livestock production. In such cases, exclosure experiments may not reflect typical outcomes of human-driven extirpations of wild herbivores. 3. Here, we examine how plant community responses to changes in the identity and abundance of large herbivores interact with abiotic factors (rainfall and soil properties). We also explore how effects of wild herbivores on plant communities differ between large-scale herbivore exclosures and landscape sites where anthropogenic activity has caused wildlife declines, often accompanied by livestock increases. 4. Abiotic context modulated the responses of plant communities to herbivore declines with stronger effect sizes in lower-productivity environments. Also, shifts in plant community structure, composition and species richness following wildlife declines differed considerably between exclosure experiments and landscape sites in which wild herbivores had declined and were often replaced by livestock. Plant communities in low wildlife landscape sites were distinct in both composition and physical structure from both exclosure and control sites in experiments. The power of environmental (soil and rainfall) gradients in influencing plant response to herbivores was also greatly dampened or absent in the landscape sites. One likely explanation for

  1. Effects of mammalian herbivore declines on plant communities: observations and experiments in an African savanna.

    PubMed

    Young, Hillary S; McCauley, Douglas J; Helgen, Kristofer M; Goheen, Jacob R; Otárola-Castillo, Erik; Palmer, Todd M; Pringle, Robert M; Young, Truman P; Dirzo, Rodolfo

    2013-07-01

    1. Herbivores influence the structure and composition of terrestrial plant communities. However, responses of plant communities to herbivory are variable and depend on environmental conditions, herbivore identity and herbivore abundance. As anthropogenic impacts continue to drive large declines in wild herbivores, understanding the context dependence of herbivore impacts on plant communities becomes increasingly important. 2. Exclosure experiments are frequently used to assess how ecosystems reorganize in the face of large wild herbivore defaunation. Yet in many landscapes, declines in large wildlife are often accompanied by other anthropogenic activities, especially land conversion to livestock production. In such cases, exclosure experiments may not reflect typical outcomes of human-driven extirpations of wild herbivores. 3. Here, we examine how plant community responses to changes in the identity and abundance of large herbivores interact with abiotic factors (rainfall and soil properties). We also explore how effects of wild herbivores on plant communities differ between large-scale herbivore exclosures and landscape sites where anthropogenic activity has caused wildlife declines, often accompanied by livestock increases. 4. Abiotic context modulated the responses of plant communities to herbivore declines with stronger effect sizes in lower-productivity environments. Also, shifts in plant community structure, composition and species richness following wildlife declines differed considerably between exclosure experiments and landscape sites in which wild herbivores had declined and were often replaced by livestock. Plant communities in low wildlife landscape sites were distinct in both composition and physical structure from both exclosure and control sites in experiments. The power of environmental (soil and rainfall) gradients in influencing plant response to herbivores was also greatly dampened or absent in the landscape sites. One likely explanation for

  2. Seismic investigations of the Nansen Ridge during the FRAM I experiment

    NASA Astrophysics Data System (ADS)

    Kristoffersen, Y.; Husebye, E. S.; Bungum, H.; Gregersen, S.

    1982-02-01

    As part of the FRAM I ice station experiment in the Arctic Ocean during the period March 11-May 15, 1979, a sonobuoy array was kept in operation for about 6 weeks. During the last two days of the experiment the array drifted over the crestal mountains of the western flank of the Nansen Ridge. Here microearthquakes were recorded at a rate of 1-2 events per hour, with epicentral distances from 15 to 25 km. Two parallel epicenter lineations are found, a main one that coincides with the median valley and another less active one that follows the northwestern rift-valley wall. This activity may be related to the uplift of a fault block from the median valley onto the rift valley wall. A crustal model for the crestal mountain area was obtained from two unreversed refraction profiles, giving preliminary compressional velocities of 4.6 km/s at the sea floor, a 6.1 km/s refractor at 1.5 km depth, and a 7.9 km/s refractor at 6 km depth, while in the median valley a 7.2 km/s refractor is found at a depth of 3 km.

  3. iMUSH: The design of the Mount St. Helens high-resolution active source seismic experiment

    NASA Astrophysics Data System (ADS)

    Kiser, Eric; Levander, Alan; Harder, Steve; Abers, Geoff; Creager, Ken; Vidale, John; Moran, Seth; Malone, Steve

    2013-04-01

    Mount St. Helens is one of the most societally relevant and geologically interesting volcanoes in the United States. Although much has been learned about the shallow structure of this volcano since its eruption in 1980, important questions still remain regarding its magmatic system and connectivity to the rest of the Cascadia arc. For example, the structure of the magma plumbing system below the shallowest magma chamber under the volcano is still only poorly known. This information will be useful for hazard assessment for the southwest Washington area, and also for gaining insight into fundamental scientific questions such as the assimilation and differentiation processes that lead to the formation of continental crust. As part of the multi-disciplinary imaging of Magma Under St. Helens (iMUSH) experiment, funded by NSF GeoPRISMS and EarthScope, an active source seismic experiment will be conducted in late summer 2014. The experiment will utilize all of the 2600 IRIS/PASSCAL/USArray Texan instruments. The instruments will be deployed as two 1000-instrument consecutive refraction profiles (one N/S and one WNW/ESE). Each of these profiles will be accompanied by two 1600-instrument areal arrays at varying distances from Mount St. Helens. Finally, one 2600-instrument areal array will be centered on Mount St. Helens. These instruments will record a total of twenty-four 500-1000 kg shots. Each refraction profile will have an average station spacing of 150 m, and a total length of 150 km. The stations in the areal arrays will be separated by ~1 km. A critical step in the success of this project is to develop an experimental setup that can resolve the most interesting aspects of the magmatic system. In particular, we want to determine the distribution of shot locations that will provide good coverage throughout the entire model space, while still allowing us to focus on regions likely to contain the magmatic plumbing system. In this study, we approach this problem by

  4. Site Characterization of the Source Physics Experiment Phase II Location Using Seismic Reflection Data

    SciTech Connect

    Sexton, Emily; Snelson, Catherine M; Chipman, Veraun D; Emer, Dudley; White, Bob; Emmit, Ryan; Wright, Al; Drellack, Sigmund; Huckins-Gang, Heather; Mercadante, Jennifer; Floyd, Michael; McGowin, Chris; Cothrun, Chris; Bonal, Nedra

    2013-12-05

    An objective of the Source Physics Experiment (SPE) is to identify low-yield nuclear explosions from a regional distance. Low-yield nuclear explosions can often be difficult to discriminate among the clutter of natural and man-made explosive events (e.g., earthquakes and mine blasts). The SPE is broken into three phases. Phase I has provided the first of the physics-based data to test the empirical models that have been used to discriminate nuclear events. The Phase I series of tests were placed within a highly fractured granite body. The evolution of the project has led to development of Phase II, to be placed within the opposite end member of geology, an alluvium environment, thereby increasing the database of waveforms to build upon in the discrimination models. Both the granite and alluvium sites have hosted nearby nuclear tests, which provide comparisons for the chemical test data. Phase III of the SPE is yet to be determined.

  5. Challenges associated with tracking resources allocation for reproductive health in sub-Saharan African countries: the UNFPA/NIDI resource flows project experience.

    PubMed

    Sidze, Estelle M; Beekink, Erik; Maina, Beatrice W

    2015-01-01

    Universal access to reproductive health services entails strengthening health systems, but requires significant resource commitments as well as efficient and effective use of those resources. A number of international organizations and governments in developing countries are putting efforts into tracking the flow of health resources in order to inform resource mobilization and allocation, strategic planning, priority setting, advocacy and general policy making. The UNFPA/NIDI-led Resource Flows Project ("The UNFPA/NIDI RF Project") has conducted annual surveys since 1997 to monitor progress achieved by developing countries in implementing reproductive health financial targets. This commentary summarizes the Project experiences and challenges in gathering data on allocation of resources for reproductive health at the domestic level in sub-Saharan African countries. One key lesson learnt from the Project experience is the need for strengthening tracking mechanisms in sub-Saharan African countries and making information on reproductive health resources and expenditures available, in particular the private sector resources. PMID:26012472

  6. Pathways to success in science: A phenomenological study, examining the life experiences of African-American women in higher education

    NASA Astrophysics Data System (ADS)

    Giscombe, Claudette Leanora

    This study is a qualitative investigation in which five African American women science faculty, in higher education, within the age range of 45--60, were the participants. The data that was collected, over twelve months, was primarily obtained from the in-depth phenomenological interviewing method (Seidman, 1991). The interpretation of the data was the result of ongoing cross analysis of the participants' life experiences, perceptions, and beliefs of the how they navigated and negotiated pathways to careers in the natural sciences, and the meanings they attach to these experiences. The software Ethnograph (V5.0) was used to organize the participants' responses into patterns and emergent themes. The Black women in this study articulated several themes that were critical determinants of their successes and achievements in science careers. From the analysis of the data set, four major findings were identified: (1) "Black Intentional Communities" acted as social agencies for the positive development of the participants; (2) "My World Reality" which was described by the participants as their acceptance of their segregated worlds, not being victims of inequities and injustices, but being resilient and determined to forge on to early academic successes. Early academic successes were identified as precursors and external motivational stimuli to their interests and achievements in science; (3) Their experiences of "Tensions and Double Consciousness" from race and gender negative images and career stereotypes, required the women to make "intra-cultural deviations" from stereotypic career roles and to develop "pragmatic coping strategies" to achieve in science careers and; (4) "Meaning-making"---Significant to the meaning of their journey was the fact that the participants grounded their experiences in a social context rather than in a scientific context and that they ended their journey with expressions of personal satisfactions about their journey and their unique drive and

  7. Results of the South African Cloud-Seeding Experiments Using Hygroscopic Flares.

    NASA Astrophysics Data System (ADS)

    Mather, G. K.; Terblanche, D. E.; Steffens, F. E.; Fletcher, L.

    1997-11-01

    A new method of seeding convective clouds for the purpose of augmenting rainfall is being developed in South Africa. Flares that produce small salt particles (0.5-m mean diameter) are attached to the trailing edge of the wings of seeding aircraft and ignited in updrafts below the cloud base of convective storms. This method of delivery overcomes most of the difficulties encountered in the handling and the use of hygroscopic materials, difficulties that made seeding with ice nuclei (AgI) a more attractive option.The research that has led to the development of this new technique was prompted by an encounter with a storm with dramatically altered microphysics that was growing over a Kraft paper mill in the research area. Hygroscopic seeding flares were subsequently developed, and seeding trials began in October 1990. Successful seeding trials quickly led to the design and execution of a randomized convective cloud-seeding experiment, the results of which show convincing evidence of increases in the radar-measured rain mass from seeded storms when compared to the control or unseeded storms.Heightened reflectivities aloft seen by the real-time storm-tracking software and observed in the exploratory analysis raises the possibility of developing a radar-measured seeding algorithm that can recognize in almost real time a successful convective seeding event. The implications of such a development would have far-reaching effects on the conduct of future convective cloud-seeding experiments and operations.The authors' seeding hypothesis postulates that the hygroscopic seeding at cloud base accelerates the growth of large hydrometeors in the treated clouds, which harvest more of the available supercooled water before it is expelled into the anvils by the strong updrafts that are a characteristic of the local storms, thereby increasing the efficiency of the rainfall process. The validity of this hypothesis is supported by microphysical measurements made from an instrumented

  8. Fault kinematics and tectonic stress in the seismically active Manyara Dodoma Rift segment in Central Tanzania Implications for the East African Rift

    NASA Astrophysics Data System (ADS)

    Macheyeki, Athanas S.; Delvaux, Damien; De Batist, Marc; Mruma, Abdulkarim

    2008-07-01

    The Eastern Branch of the East African Rift System is well known in Ethiopia (Main Ethiopian Rift) and Kenya (Kenya or Gregory Rift) and is usually considered to fade away southwards in the North Tanzanian Divergence, where it splits into the Eyasi, Manyara and Pangani segments. Further towards the south, rift structures are more weakly expressed and this area has not attracted much attention since the mapping and exploratory works of the 1950s. In November 4, 2002, an earthquake of magnitude Mb = 5.5 struck Dodoma, the capital city of Tanzania. Analysis of modern digital relief, seismological and geological data reveals that ongoing tectonic deformation is presently affecting a broad N-S trending belt, extending southward from the North Tanzanian Divergence to the region of Dodoma, forming the proposed "Manyara-Dodoma Rift segment". North of Arusha-Ngorongoro line, the rift is confined to a narrow belt (Natron graben in Tanzania) and south of it, it broadens into a wide deformation zone which includes both the Eyasi and Manyara grabens. The two-stage rifting model proposed for Kenya and North Tanzania also applies to the Manyara-Dodoma Rift segment. In a first stage, large, well-expressed topographic and volcanogenic structures were initiated in the Natron, Eyasi and Manyara grabens during the Late Miocene to Pliocene. From the Middle Pleistocene onwards, deformations related to the second rifting stage propagated southwards to the Dodoma region. These young structures have still limited morphological expressions compared to the structures formed during the first stage. However, they appear to be tectonically active as shown by the high concentration of moderate earthquakes into earthquake swarms, the distribution of He-bearing thermal springs, the morphological freshness of the fault scarps, and the presence of open surface fractures. Fault kinematic and paleostress analysis of geological fault data in basement rocks along the active fault lines show that recent

  9. Blockage and flow: intimate experiences of condoms and microbicides in a South African clinical trial.

    PubMed

    Stadler, Jonathan; Saethre, Eirik

    2011-01-01

    Based on qualitative research undertaken during a phase-three microbicide gel trial, this paper explores female participants' experiences and perceptions of gel and condom use and the opinions of their male partners and community members. Participants were aware that condoms were effective in preventing HIV infection and that the efficacy of the microbicide was unproven. Yet, in narratives about gel and condom use, participants ascribed improvements to their reproductive health and intimate relationships with men to gel use. In contrast, condoms were believed to prevent disease, yet also embodied mistrust, were believed to contain dangerous substances and were felt to block the womb. These apparently contradictory views about condoms and gels are explored in the light of conceptions of flow and blockage. Health is achieved by maintaining a steady balance of substances within the body, while preventing fluid flow results in illness. We argue that women enrolled in the trial broadened the meaning of the gel beyond its primary intended effect of preventing HIV. Through their accounts of gel use, women 'reinvented' the gel as a substance that transformed their bodies and sexual relations. This has implications for understanding how local knowledge of health and illness intersects with biomedical knowledge. PMID:20960355

  10. The spectrum of injuries resulting from posterior abdominal stab wounds: a South African experience

    PubMed Central

    Oosthuizen, GV; Clarke, DL

    2015-01-01

    Introduction The spectrum of injury associated with anterior abdominal stab wounds (SWs) is well established. The literature on the spectrum of organ injury associated with SWs to the posterior abdomen, however, is limited. Methods We reviewed our experience of 105 consecutive patients who had established indications for laparotomy managed over a 4-year period in a high volume trauma service in South Africa. Results Of the 105 patients, 97 (92%) were male and the overall mean age was 24 years. Fifty-seven patients (54%) had immediate indications for laparotomy. The remaining 48 patients (46%) initially underwent active clinical observation and the indications for laparotomy became apparent during the observation period. Of the 105 laparotomies performed, 94 (90%) were positive and 11 (10%) were negative. Of the 94 positive laparotomies, 92 were therapeutic and 2 were non-therapeutic. A total of 176 organ injuries were identified: 50 (53%) of the 94 patients sustained a single organ injury while the remaining 44 (47%) sustained multiple organ injuries. The most commonly injured organs were the colon (n=63), spleen (n=21) and kidney (n=19). Conclusions The pattern of intra-abdominal injuries secondary to SWs to the posterior abdomen is different to that seen with the anterior abdomen. Colonic injury is most commonly encountered, followed by injuries to the spleen and kidney. Clinicians must remain vigilant because of the potential for occult injuries. PMID:26263933

  11. The GLIMPCE seismic experiment: Onshore refraction and wide-angle reflection observations from a fan line over the Lake Superior Midcontinent Rift System

    NASA Astrophysics Data System (ADS)

    Epili, Duryodhan; Mereu, Robert F.

    The 1986 GLIMPCE experiment (Great Lakes International Multidisciplinary Program for Crustal Evolution) was a combined on-ship seismic reflection and onshore seismic refraction experiment designed to determine the structure of the crust beneath the Great Lakes. The main tectonic targets of interest were the Midcontinent Rift System, the Grenville Front, the Penokean and Huronian Fold Belts and the Michipicoten Greenstone Belt. The source of the seismic energy came from a large air gun array fired at closely spaced intervals (50-350 m) over several long lines (150-350 km) crossing the lakes. Major participants of this experiment were the Geological Survey of Canada, the United States Geological Survey and a number of universities and research institutes on both sides of the border. The University of Western Ontario (UWO) collected data at five separate land stations using portable seismic refraction instruments. In this paper we present the results of a fan profile which was recorded from a UWO station on Michipicoten Island for the N-S line A which crossed the axis of the Lake Superior Synclinal Basin. The azimuth and distance ranges for this profile were 237 to 321 degrees and 120 to 170 km respectively. Detailed observations of the record sections show that p. is not a simple arrival but forms a rather complex pattern of irregular multiple arrivals. The wide-angle PmP reflection signals from the Moho are strong and well obilerved only for the shots fired near the ends of the line. The signals from the middle of the profile arrive relatively late and form very weak complex wave trains. These results indicate that the Moho in that area is probably greatly disrupted and gives added support to the rift theory for the structure under the lake. The observations also support the results of earlier crustal studies of Lake Superior which showed that the crust under the eastern part of the lake was exceedingly thick.

  12. Testing Models of Magmatic and Hydrothermal Segmentation: A Three-Dimensional Seismic Tomography Experiment at the Endeavour Ridge (Invited)

    NASA Astrophysics Data System (ADS)

    Wilcock, W. S.; Toomey, D. R.; Hooft, E. E.; Weekly, R. T.; Wells, A. E.

    2010-12-01

    Competing models for what controls the segmentation and intensity of ridge crest processes are at odds on the scale of mantle and crustal magmatic segmentation, the distribution of hydrothermal venting with respect to a volcanic segment and the properties of the thermal boundary layer that transports energy between the magmatic and hydrothermal systems. The presence of an axial magma chamber (AMC) reflector beneath the central portion of the Endeavour segment of the Juan de Fuca ridge, as well as systematic along axis changes in seafloor depth, ridge crest morphology and hydrothermal venting provide an ideal target for testing conflicting hypotheses. In late summer 2009, we conducted an active source seismic experiment on the Endeavour segment of the Juan de Fuca Ridge. A total of 5,567 airgun shots from the 36-gun, 6,600 in3 airgun array of the R/V Marcus G. Langseth were recorded by 68 short-period ocean bottom seismometers (OBSs) deployed at 64 sites. The experimental geometry utilized 3 nested scales and was designed to image (1) crustal thickness variations within 25 km of the axial high (0 to 900 kyr); (2) the map view heterogeneity and anisotropy of the topmost mantle beneath the spreading axis; (3) the three-dimensional structure of the crustal magmatic system and (4) the detailed three-dimensional, shallow crustal thermal structure beneath the Endeavour vent fields. At the segment scale, six 100-km-long ridge-parallel shot lines were obtained at distances of 16, 23 and 30 km to both sides of the ridge axis with OBSs on all but the outer lines. At the along-axis scale of the AMC reflector, shot lines are spaced 1 km apart and OBSs 8 km apart within a 60 x 20 km2 region. At the vent field scale, shots were obtained on a 500 x 500 m2 grid and OBSs spaced 5 km apart within a 20 x 10 km2 region. All the shooting lines were collected with a 9 m source depth to obtain impulsive arrivals at shorter ranges but the outer lines were also shot with a 15 m source depth

  13. Monitoring of glacial seismic events from Greenland at regional distances: experience from the POLENET/LAPNET experiment during the IPY 2007-2009

    NASA Astrophysics Data System (ADS)

    Kozlovskaya, E.; Pedersen, H.; Plomerova, J.; Achauer, U.; Kissling, E. H.; Sanina, I.; Jämsen, T.; Silvennoinen, H.; Pequegnat, C.; Hurskainen, R.; Hausmann, H.; Jedlicka, P.; Aleshine, I.; Bourova, E.; Bodvarsson, R.; Brueckl, E. P.; Eken, T.; Heikkinen, P. J.; Houseman, G. A.; Johnsen, H.; Kari, K.; Munzarova, H.; Roberts, R.; Ruzek, B.; Hosein Shomali, Z.; Schweitzer, J.; Shaumyan, A.; Vecsey, L.; Volosov, S.

    2010-12-01

    Monitoring of glacial earthquakes from Greenland was one of the major targets of the POLENET/LAPNET passive seismic experiment in northern Fennoscandia (northern parts of Finland, Sweden, Norway and Russian Karelia) during the IPY 2007-2009. The POLENET/LAPNET array, with the average spacing between stations of 70 km, was designed to solve specific tasks of polar seismology. The collected POLENET/LAPNET dataset includes high-frequency continuous data (sampling rate from 50 to 100 sps) of 37 temporary stations, which were in operation during the time frame from 01.05.2008 to 31.09.2009, and of 21 stations of selected permanent networks in Fennoscandia. The first results of the experiment have shown that the POLENET/LAPNET array, located at regional distances from Greenland, recorded more such events than it has been recorded by the Global Seismographic Network during the same observation period. The waveforms of events recorded by the array differ from both long-period waveforms of glacial earthquakes recorded at teleseismic distances and from short-period glacial rumblings recorded at local distances. Recordings of glacial earthquakes obtained by the array contain the long-period energy only. In many cases the events were recorded in groups within the time interval of up to 1 hour. Generally, the waveforms of events within the same group are different and the events not always originate from the same location. For some of the events it was possible to recognize not only dispersed long-period surface wave, but also the first arrival of a long-period P-wave. This suggests that source duration of these events was long. Diversity of the waveforms of glacial events recorded by the POLENET/LAPNET array can be considered as evidence for diversity of source mechanisms of these events.

  14. Comparative sequence stratigraphy of low-latitude versus high-latitude lacustrine rift basins: Seismic data examples from the East African and Baikal rifts

    USGS Publications Warehouse

    Scholz, C.A.; Moore, T.C., Jr.; Hutchinson, D.R.; Golmshtok, A. Ja; Klitgord, Kim D.; Kurotchkin, A.G.

    1998-01-01

    Lakes Baikal, Malawi and Tanganyika are the world's three largest rift valley lakes and are the classic modem examples of lacustrine rift basins. All the rift lakes are segmented into half-graben basins, and seismic reflection datasets reveal how this segmentation controls the filling of the rift basins through time. In the early stages of rifting, basins are fed primarily by flexural margin and axial margin drainage systems. At the climax of syn-rift sedimentation, however, when the basins are deeply subsided, almost all the margins are walled off by rift shoulder uplifts, and sediment flux into the basins is concentrated at accommodation zone and axial margin river deltas. Flexural margin unconformities are commonplace in the tropical lakes but less so in high-latitude Lake Baikal. Lake levels are extremely dynamic in the tropical lakes and in low-latitude systems in general because of the predominance of evaporation in the hydrologic cycle in those systems. Evaporation is minimized in relation to inflow in the high-latitude Lake Baikal and in most high-latitude systems, and consequently, major sequence boundaries tend to be tectonically controlled in that type of system. The acoustic stratigraphies of the tropical lakes are dominated by high-frequency and high-amplitude lake level shifts, whereas in high-latitude Lake Baikal, stratigraphic cycles are dominated by tectonism and sediment-supply variations.

  15. 1978 Yellowstone-eastern Snake River Plain seismic profiling experiment: Data and upper crustal structure of the Yellowstone region

    SciTech Connect

    Schilly, M.M.; Smith, R.B.; Braile, L.W.; Ansorge, J.

    1982-04-10

    Eleven in-line refraction profiles, recorded to distances of 300 km, and one azimuthal fan plot were constructed from data recorded with a 150-station array in the Yellowstone National Park area during the 1978 Yellowstone-Snake River Plain seismic experiment. Interpretations of the data suggest that the crustal P wave velocity model for the Yellowstone region is characterized by (1) an averaged 10-km-thick upper crustal layer, V/sub p/ = 6.0 km/s, (2) an average crustal velocity of 6.3 km/s, and (3) a total crustal thickness of 44 km. Velocity models are presented for profiles that emphasize the upper crust and show (1) a decrease in the depth to the top of the upper crustal crystalline basement from 5 km in southwestern Yellowstone near Island Park to 1 km at the northeast side of the Yellowstone Plateau that is interpreted as a progressive thinning of the silicic surface volcanic layer to the northeast and (2) evidence for a large lateral inhomogeneity interpreted to be a low-velocity body, with a decrease of at least 10% in P wave velocity, located beneath the northeast corner of the Yellowstone Plateau. The low-velocity zone coincides with a local -30-mgal residual gravity anomaly and is located beneath part of the Sour Creek resurgent dome and part of the Hot Springs Basin, the largest hydrothermal system in Yellowstone. The low-velocity body has a maximum depth to the top of 3 km and a minimum depth to the bottom of 9 km and may represent a zone of partial melt. In comparison to the thermally undisturbed upper crust of the surrounding Rocky Mountains the upper crust of the northeastern Yellowstone plateau appears laterally inhomogeneous in velocity and layer thickness, suggesting effects of thermal and magma intrusion, whereas the lower crust appears relatively homogeneous.

  16. Seismic moment tensors of acoustic emissions recorded during laboratory rock deformation experiments: sensitivity to attenuation and anisotropy

    NASA Astrophysics Data System (ADS)

    Stierle, Eva; Vavryčuk, Václav; Kwiatek, Grzegorz; Charalampidou, Elli-Maria; Bohnhoff, Marco

    2016-04-01

    Seismic moment tensors can provide information on the size and orientation of fractures producing acoustic emissions (AEs) and on the stress conditions in the sample. The moment tensor inversion of AEs is, however, a demanding procedure requiring carefully calibrated sensors and accurate knowledge of the velocity model. In field observations, the velocity model is usually isotropic and time independent. In laboratory experiments, the velocity is often anisotropic and time dependent and attenuation might be significant due to opening or closure of microcracks in the sample during loading. In this paper, we study the sensitivity of the moment tensor inversion to anisotropy of P-wave velocities and attenuation. We show that retrieved moment tensors critically depend on anisotropy and attenuation and their neglect can lead to misinterpretations of the source mechanisms. The accuracy of the inversion also depends on the fracturing mode of AEs: tensile events are more sensitive to P-wave anisotropy and attenuation than shear events. We show that geometry of faulting in anisotropic rocks should be studied using the source tensors, since the P- and T-axes of the moment tensors are affected by velocity anisotropy and deviate from the true orientation of faulting. The stronger the anisotropy is, the larger the deviations are. Finally, we prove that the moment tensor inversion applied to a large dataset of AEs can be utilized to provide information on the attenuation parameters of the rock sample. The method is capable of measuring anisotropic attenuation in the sample and allows for detection of dilatant cracking according to the stress regime.

  17. Seafloor surface processes and subsurface paleo-channel unconformities mapped using multi-channel seismic and multi-beam sonar data from the Galicia 3D seismic experiment.

    NASA Astrophysics Data System (ADS)

    Gibson, J. C.; Shillington, D. J.; Sawyer, D. S.; Jordan, B.; Morgan, J. K.; Ranero, C.; Reston, T. J.

    2015-12-01

    In this study we use geophysical methods, stratigraphic relationships, and coring/drilling leg results to assess possible controls on deep-sea channel formation in order to further constrain paleo-channel (PC) and associated unconformity timing/source processes. A series of cut and fill PC are mapped in 3D multi-channel seismic (MCS) data and compared with multi-beam (MB) sonar bathymetry/backscatter data collected during the Galicia 3D survey with the R/V Marcus G. Langseth (2013). The MCS data were collected using four 6 km streamers spaced at 200 m resulting in 25 m x 25 m common mid-point bins within the ~67 km x 20 km 3D volume. The MB data were collected at an average depth of ~4900 m with a constrained swath width of 4.5 km resulting in 11.25x overlap while enabling 25-m bathymetry and 10-m backscatter grids. The PC lie below the mouth of a submarine canyon at the edge of the Galicia abyssal plain and cut pre/syn-rift sediments; they are bound by a rift block to the north and paleo-levees to the south (maximum height of ~180m). From drilling results, the most recent PC is late Miocene in age. In this study, four PC are traced into the basin as unconformities. Several of the PC/unconformities are tentatively correlated with previously interpreted Pyrenean orogeny/compressional Miocene/Oligocene tectonic events. However, one PC/unconformity within this interval has not been previously interpreted. In order test the hypothesis that the unconformities are the result of a significant change in base level indicated by a low shale/sand (SS) ratio, we use seismic surface attributes to calculate the SS ratio and trace the horizontal extent of the unconformities. Additionally, the MB/MCS seafloor morphology reveals sedimentary waves outboard of the canyon mouth. We use backscatter data to compare the extent of recent processes (e.g., Pleistocene glaciation/de-glaciation) with the unconformities by mapping the surface/shallow subsurface SS ratio (volume scattering).

  18. Involving lay community researchers in epidemiological research: experiences from a seroprevalence study among sub-Saharan African migrants

    PubMed Central

    Nöstlinger, Christiana; Loos, Jasna

    2016-01-01

    ABSTRACT Community-based participatory research (CBPR) has received considerable attention during past decades as a method to increase community ownership in research and prevention. We discuss its application to epidemiological research using the case of second-generation surveillance conducted among sub-Saharan African (SSA) migrants in Antwerp city. To inform evidence-based prevention planning for this target group, this HIV-prevalence study used two-stage time-location sampling preceded by formative research. Extensive collaborative partnerships were built with community organizations, a Community Advisory Board provided input throughout the project, and community researchers were trained to participate in all phases of the seroprevalence study. Valid oral fluid samples for HIV testing were collected among 717 SSA migrants and linked to behavioural data assessed through an anonymous survey between December 2013 and August 2014. A qualitative content analysis of various data sources (extensive field notes, minutes of intervision, and training protocols) collected at 77 data collection visits in 51 settings was carried out to describe experiences with challenges and opportunities inherent to the CBPR approach at three crucial stages of the research process: building collaborative partnerships; implementing the study; dissemination of findings including prevention planning. The results show that CBPR is feasible in conducting scientifically sound epidemiological research, but certain requirements need to be in place. These include among others sufficient resources to train, coordinate, and supervise community researchers; continuity in the implementation; transparency about decision-taking and administrative procedures, and willingness to share power and control over the full research process. CBPR contributed to empowering community researchers on a personal level, and to create greater HIV prevention demand in the SSA communities. PMID:26885938

  19. Involving lay community researchers in epidemiological research: experiences from a seroprevalence study among sub-Saharan African migrants.

    PubMed

    Nöstlinger, Christiana; Loos, Jasna

    2016-01-01

    Community-based participatory research (CBPR) has received considerable attention during past decades as a method to increase community ownership in research and prevention. We discuss its application to epidemiological research using the case of second-generation surveillance conducted among sub-Saharan African (SSA) migrants in Antwerp city. To inform evidence-based prevention planning for this target group, this HIV-prevalence study used two-stage time-location sampling preceded by formative research. Extensive collaborative partnerships were built with community organizations, a Community Advisory Board provided input throughout the project, and community researchers were trained to participate in all phases of the seroprevalence study. Valid oral fluid samples for HIV testing were collected among 717 SSA migrants and linked to behavioural data assessed through an anonymous survey between December 2013 and August 2014. A qualitative content analysis of various data sources (extensive field notes, minutes of intervision, and training protocols) collected at 77 data collection visits in 51 settings was carried out to describe experiences with challenges and opportunities inherent to the CBPR approach at three crucial stages of the research process: building collaborative partnerships; implementing the study; dissemination of findings including prevention planning. The results show that CBPR is feasible in conducting scientifically sound epidemiological research, but certain requirements need to be in place. These include among others sufficient resources to train, coordinate, and supervise community researchers; continuity in the implementation; transparency about decision-taking and administrative procedures, and willingness to share power and control over the full research process. CBPR contributed to empowering community researchers on a personal level, and to create greater HIV prevention demand in the SSA communities. PMID:26885938

  20. Seismic structure of uppermost mantle and crust beneath West Philippine Basin and Kyusyu-Palau ridge by seafloor borehole seismometer, OBS and airgun experiment

    NASA Astrophysics Data System (ADS)

    Arisaka, M.; Shinohara, M.; Yamada, T.; Mochizuki, K.; Kaiho, Y.; Araki, E.; Nakahigashi, K.; Ito, M.; Shiobara, H.; Suehiro, K.; Kanazawa, T.

    2003-12-01

    The western Pacific area including the Philippine Sea plate is characterized by many island-arc and trench systems and back-arc basins, which are estimated to correspond to subduction of oceanic plates. The Philippine Sea plate is divided into two regions by the Kyushu-Palau Ridge running from north to south. There are the Shikoku basin and the Parece-Vela basin in the eastern part, and the West Philippine basin exists in the western part. It is important to study an uppermost mantle and crustal seismic structure of the Philippine Sea plate to consider the formation process and to estimate the development process of an island-arc and trench system. In addition, the borehole broadband seismic station (WP-1) was installed in the easternmost part of the West Philippine basin in 2001 and is in operation. To obtain the seismic structure is also important for analyses of the data retrieved from the WP-1. We conducted seismic surveys with ocean bottom seismometers (OBS), the WP-1 and controlled sources to obtain the seismic crustal structure around the WP-1 observatory March 2002, October 2002 and May 2003 using the R/V KAIREI, JAMSTEC. The total length of the profile parallel to the ridge (NS line) is about 100 km. The profile perpendicular to the ridge (EW line) has approximately 120 km long in total and crosses the ridge and the WP-1 borehole seismometer. As the controlled sources, we used a GI gun (3 liters) and Bolt 1500LL type (1500cu.in.) airguns. Number and kind of airguns differed in each experiment. Total 12 OBSs were deployed at an average interval of 10km(NS line) and 15km (EW line) for the experiments. A seismic velocity model for shallow structure is derived from using a tau-p inversion of individual OBS records. A deep structure beneath the profile is estimated by using a two-dimensional ray tracing method. The preliminary results for the NS line are obtained. P-wave velocity of the sedimentary layer is 2.7 km/s and the thickness is about 500 m. These

  1. Passive seismic experiment and receiver functions analysis to determine crustal structure at the contact of the northern Dinarides and southwestern Pannonian Basin

    NASA Astrophysics Data System (ADS)

    Šumanovac, Franjo; Hegedűs, Endre; Orešković, Jasna; Kolar, Saša; Kovács, Attila C.; Dudjak, Darko; Kovács, István J.

    2016-06-01

    Passive seismic experiment was carried out at the SW contact of the Dinarides and Pannonian basin to determine the crustal structure and velocity discontinuities. The aim of the experiment was to define the relationship between the Adriatic microplate and the Pannonian segment as a part of the European plate. Most of the temporary seismic stations were deployed in Croatia along the Alp07 profile-a part of the active-source ALP 2002 project. About 300-km-long profile stretches from Istra peninsula to the Drava river, in a WSW-ESE direction. Teleseismic events recorded on 13 temporary seismic stations along the profile were analysed by P-receiver function method. Two types of characteristic receiver functions (RF) have been identified, belonging to Dinaridic and Pannonian crusts as defined on the Alp07 profile, while in transitional zone there are both types. Three major crustal discontinuities can be identified for the Dinaridic type: sedimentary basement, intracrustal discontinuity and Mohorovičić discontinuity, whereas the Pannonian type revealed only two discontinuities. The intracrustal discontinuity was not observed in the Pannonian type, thus pointing to a single-layered crust in the Pannonian basin. Two interpretation methods were applied: forward modelling of the receiver functions and H-κ stacking method, and the results were compared with the active-source seismic data at deep refraction profile Alp07. The receiver function modelling has given reliable results of the Moho depths that are in accordance with the seismic refraction results at the end of the Alp07 profile, that is in the area of Pannonian crust characterized by simple crustal structure and low seismic velocities (Vp between 5.9 and 6.2 km s-1). In the Dinarides and its peripheral parts, receiver function modelling regularly gives greater Moho depths, up to +15 per cent, due to more complex crustal structure. The depths of the Moho calculated by the H-κ stacking method vary within wide

  2. Passive seismic experiment and receiver functions analysis to determine crustal structure at the contact of the northern Dinarides and southwestern Pannonian Basin

    NASA Astrophysics Data System (ADS)

    Šumanovac, Franjo; Hegedűs, Endre; Orešković, Jasna; Kolar, Saša; Kovács, Attila C.; Dudjak, Darko; Kovács, István J.

    2016-03-01

    Passive seismic experiment was carried out at the SW contact of the Dinarides and Pannonian basin to determine the crustal structure and velocity discontinuities. The aim of the experiment was to define the relationship between the Adriatic microplate and the Pannonian segment as a part of the European plate. Most of the temporary seismic stations were deployed in Croatia along the Alp07 profile - a part of the active-source ALP 2002 project. About 300 km long profile stretches from Istra peninsula to the Drava river, in a WSW-ESE direction. Teleseismic events recorded on 13 temporary seismic stations along the profile were analysed by P-receiver function method. Two types of characteristic receiver functions (RF) have been identified, belonging to Dinaridic and Pannonian crusts as defined on the Alp07 profile, while in transitional zone there are both types. Three major crustal discontinuities can be identified for the Dinaridic type: sedimentary basement, intracrustal discontinuity and Mohorovičić discontinuity, whereas the Pannonian type revealed only two discontinuities. The intracrustal discontinuity was not observed in the Pannonian type, thus pointing to a single-layered crust in the Pannonian basin. Two interpretation methods were applied: forward modelling of the receiver functions and H-κ stacking method, and the results were compared with the active-source seismic data at deep refraction profile Alp07. The receiver function modelling has given reliable results of the Moho depths that are in accordance with the seismic refraction results at the end of the Alp07 profile, i.e. in the area of Pannonian crust characterised by simple crustal structure and low seismic velocities (Vp between 5.9 and 6.2 km s-1). In the Dinarides and its peripheral parts, receiver function modelling regularly gives greater Moho depths, up to +15%, due to more complex crustal structure. The depths of the Moho calculated by the H-κ stacking method vary within wide limits (±13

  3. Experiences and Perspectives of African-American, Latina/o, Asian-American and European-American Psychology Graduate Students: A National Study

    PubMed Central

    Maton, Kenneth I.; Wimms, Harriette E.; Grant, Sheila K.; Wittig, Michele A.; Rogers, Margaret R.; Vasquez, Melba J. T.

    2013-01-01

    A national, web-based survey of 1,222 African-American, Latina/o, Asian-American and European-American psychology graduate students revealed both similarities and differences in experiences and perspectives. Mentoring was found to be the strongest predictor of satisfaction across groups. Academic supports and barriers, along with perceptions of diversity were also important predictors of satisfaction. Students of color differed from European-American students in perceptions of fairness of representation of their ethnic group within psychology, and in aspects of the graduate school experience perceived as linked to ethnicity. Limitations of the study and implications for future research and action are discussed. PMID:21341899

  4. Report for borehole explosion data acquired in the 1999 Los Angeles Region Seismic Experiment (LARSE II), Southern California; Part II, Data tables and plots

    USGS Publications Warehouse

    Murphy, Janice M.; Fuis, Gary S.; Okaya, D.A.; Thygesen, Kristina; Baher, Shirley A.; Rybert, Trond; Kaip, Galen; Fort, Michael D.; Asudeh, Isa; Sell, Russell

    2002-01-01

    The Los Angeles Region Seismic Experiment (LARSE), a joint project of the U.S. Geological Survey (USGS) and the Southern California Earthquake Center (SCEC), was conducted to produce seismic images of the subsurface in the Los Angeles region. Primary targets were major fault systems and sedimentary basins; the goal of the project was to address the earthquake hazard posed by these geologic features. The first phase of data collection (LARSE 1) was completed in 1994; the second phase (LARSE 2) was completed in 1999. A description of the 1999 survey and an overview of both phase I and II is given in Fuis and others (2001). In this report, we present the technical details for the explosion data collected in 1999.

  5. Building capacity for the assessment of HIV drug resistance: experiences from the PharmAccess African Studies to Evaluate Resistance network.

    PubMed

    Hamers, Raph L; Straatsma, Elske; Kityo, Cissy; Wallis, Carole L; Stevens, Wendy S; Sigaloff, Kim C E; Siwale, Margaret; Conradie, Francesca; Botes, Mariette E; Mandaliya, Kishor; Wellington, Maureen; Osibogun, Akin; van Vugt, Michèle; Rinke de Wit, Tobias F

    2012-05-01

    The PharmAccess African Studies to Evaluate Resistance (PASER) network was established as a collaborative partnership of clinical sites, laboratories, and research groups in 6 African countries; its purpose is to build research and laboratory capacity in support of a coordinated effort to assess population-level acquired and transmitted human immunodeficiency virus type-1 drug resistance (HIVDR), thus contributing to the goals of the World Health Organization Global HIV Drug Resistance Network. PASER disseminates information to medical professionals and policy makers and conducts observational research related to HIVDR. The sustainability of the network is challenged by funding limitations, constraints in human resources, a vulnerable general health infrastructure, and high cost and complexity of molecular diagnostic testing. This report highlights experiences and challenges in the PASER network from 2006 to 2010. PMID:22544185

  6. Crust Structure across the Longmen Shan Thrust Belt from Seismic Refraction and Wide-angle Reflection Experiment of Sinoprobe02

    NASA Astrophysics Data System (ADS)

    Zhu, X.; Gao, R.; Keller, R. G.; Li, Q.; Guan, Y.; Li, Y.; Li, W.; Lu, Z.; Wang, H.; Xiong, X.; Hou, H.; Dong, J.; Guo, X.; Ye, Z.; Xu, X.; Holloway, S. D.; Chang, J. C.; Kaip, G.; Ingate, S. F.

    2012-12-01

    In this study the seismic refraction and wide-angle reflection experiment has been carried out along a profile (~430 km) across the Songpan-Ganzê block of Eastern Tibet, the Longmen Shan orogenic belt to Sichuan block of the Yangtze craton. Combining with 5 wide-angle refraction seismic profiles of the Global Geoscience Transects (GGT) project carried out in 1986, a velocity model based on traveltime tomography using only the first arrivals of phases Pg and Pn has been obtained and its relative tectonic interpretation has been presented. There are strong deformations of the crust structure in the model from southern part of Songpan-Ganzê block of Eastern Tibet to the northern part of Sichuan block of the Yangtze craton. The thickness of crust varies along the profile as follow: 61~62 km in the area of Songpan-Ganzê block due to the subduction of the Tibetan plateau, 44~47 km beneath Longmen Shan orogenic belt and ~43km in the north part of the Sichuan basin. The thickness of upper crust of the Songpan-Ganzê fold belt changes regularly from the ~20km in the northwest to ~10km in the southeast. However, it is very stable in the Sichuan basin and the thickness is 16~18 km. The total thicknesses of the middle and lower crust beneath the Songpan-Ganzê fold belt change from ~50km in the Eastern Tibetan plateau to ~40km in the Western Yangtze plateau. In the frontal of Sichuan basin the thickness of them decreases to ~30km and is very stable. From the northwest to southeast , the depth of Moho varies from ~62km in the Tibetan plateau, ~60km beneath the Songpan-Ganzê fold belt in the Yangtze plateau, ~45km beneath the Longmen Shan orogenic belt, to ~43km in the Sichuan basin. The discontinuous Moho and existence of double-Moho beneath the Longmen Shan orogenic belt indicate that parts of Moho have been detached from the other parts and escaped downward from their original locations, and it has caused the uplifting and intrusion of magma from the mantle. The velocity

  7. Application of a cross correlation-based picking algorithm to active seismic signals from experiments in Tenerife Island (Canary Islands, Spain)

    NASA Astrophysics Data System (ADS)

    Garcia-Yeguas, A.; Granados, M.; Garcia, L.; Benitez, C.; De la Torre, A.; Alvarez, I.; Diaz, A.; Ibañez, J.

    2013-12-01

    The detection of the arrival time of seismic waves or picking is of great importance in many seismology applications. Traditionally, picking has been carried out by human operators. This process is not systematic and relies completely on the expertise and judgment of the analysts. The limitations of manual picking and the increasing amount of data daily stored in the seismic networks worldwide distributed led to the development of automatic picking algorithms. The accuracy of conventional 'short-term average over long-term average' (STA/LTA) algorithm, the recently developed 'Adaptive Multiband Picking Algorithm' (AMPA) and the proposed cross correlation-based picking algorithm have been assessed using a huge data set composed by active seismic signals from experiments in Tenerife Island (Canary Islands, Spain). The experiment consisted of the deployment of a dense seismic network on Tenerife Island (125 seismometers in total) and the shooting of air-guns around the island with the Spanish Oceanographic Vessel Hespérides (6459 air shots in total). Thus, more than 800.000 signals were recorded and subsequently manually picked. Since the sources and receivers locations are known and considering that the ship travelled a small distance between two consecutive shots, a picking algorithm based on cross-correlation has been proposed. The main advantage of this approach is that the algorithm does not require to set up sophisticated parameters, in contrast to other automatic algorithms. This work was supported in part by the CEI BioTic Granada project (COD55), the Spanish mineco project APASVO (TEC2012-31551), the Spanish micinn project EPHESTOS (CGL2011-29499-C02-01) and the EU project MED-SUV.

  8. The RAMESSES experiment-II. Evidence for accumulated melt beneath a slow spreading ridge from wide-angle refraction and multichannel reflection seismic profiles

    NASA Astrophysics Data System (ADS)

    Navin, D. A.; Peirce, C.; Sinha, M. C.

    1998-12-01

    The RAMESSES study (Reykjanes Axial Melt Experiment: Structural Synthesis from Electromagnetics and Seismics) targeted an apparently magmatically active axial volcanic ridge (AVR), centred on 57°45'N at the Reykjanes Ridge, with the aim of investigating the processes of crustal accretion at a slow spreading mid-ocean ridge. As part of this multicomponent experiment, airgun and explosive wide-angle seismic data were recorded by 10 digital ocean-bottom seismometers (OBSs) along profiles oriented both across- and along-axis. Coincident normal-incidence seismic, bathymetry and underway gravity and magnetic data were also collected. Forward modelling of the seismic and gravity data has revealed layer thicknesses, velocities and densities similar to those observed elsewhere within the oceanic crust near mid-ocean ridges. At 57°45'N, the Reykjanes Ridge has a crustal thickness of approximately 7.5 km on-axis. However, the crust is modelled to decrease in thickness slightly off-axis (i.e. with age), which implies that full crustal thickness is achieved on-axis and that it is subsequently thinned, most likely, by off-axis extension. Modelling also indicates that the AVR is underlain by a thin (~100 m), narrow (~4 km) melt lens some 2.5 km beneath the seafloor, which overlies a broader zone of partial melt approximately 8 km in width. Thus the results of this study provide the first clear evidence for a crustal magma chamber beneath any slow spreading ridge. The size and depth of this magma chamber (the melt lens and underlying zone of partial melt) are similar to those observed beneath fast and intermediate spreading ridges, which implies that the processes of crustal accretion are similar at all spreading rates. Hence the lack of previous observations of magma chambers beneath slow spreading ridges is probably temporally related to the periods of magmatic activity being considerably shorter and more widely spaced in time than at fast and intermediate spreading ridges.

  9. A hermeneutic phenomenological study of the experiences of female African American undergraduate engineering students at a predominantly White and an historically Black institution

    NASA Astrophysics Data System (ADS)

    Frillman, Sharron Ann

    2011-12-01

    This phenomenological study examined the experiences of twelve female African Americans enrolled as fulltime undergraduate engineering students at North Carolina Agricultural and Technical State University, an historically Black university, and seven female African Americans enrolled as undergraduate engineering students at Purdue University in West Lafayette, Indiana, a traditionally White institution. Interviews provided insights into the "lived" experiences of these young women and the factors they believe have contributed to their success in their respective engineering programs. Data analysis involved coding each participant's responses to interview questions using Atlas.ti, a powerful qualitative data analysis tool. This generated 181 codes that were further categorized into nine emergent themes, indicating the potential for extensive associations among the variables. The emergent themes are as follows: (1) Demographic information/special circumstances, (2) Personal attributes and characteristics, (3) Personal insights, (4) Sense of mission, (5) Sources of negative stress, (6) Success strategies, (7) Various forms of support, (8) Would/would not have made it to where she is now, and (9) Being African American and female in engineering. Analysis of these themes and their relationships led to the development of the Frillman Model of Emergent Themes in Female African American Engineering Students. Success. In addressing similarities and differences, three overriding theme categories emerged. These were: (1) Four personhood themes and dual social identity theme; (2) Environmental input and response theme; and (3) Outcome emergent theme of Would/Would not have made it to where she is now. Recommendations were made for future research to expand upon this exploratory study.

  10. Change Detection via Cross-Borehole and VSP Seismic Surveys for the Source Physics Experiments (SPE) at the Nevada National Security Site (NNSS)

    NASA Astrophysics Data System (ADS)

    Knox, H. A.; Abbott, R. E.; Bonal, N. D.; Aldridge, D. F.; Preston, L. A.; Ober, C.

    2012-12-01

    In support of the Source Physics Experiment (SPE) at the Nevada National Security Site (NNSS), we have conducted two cross-borehole seismic experiments in the Climax Stock. The first experiment was conducted prior to the third shot in this multi-detonation program using two available boreholes and the shot hole, while the second experiment was conducted after the shot using four of the available boreholes. The first study focused on developing a well-characterized 2D pre-explosion Vp model including two VSPs and a seismic refraction survey, as well as quantifying baseline waveform similarity at reoccupied sites. This was accomplished by recording both "sparker" and accelerated weight drop sources on a hydrophone string and surface geophones. In total more than 18,500 unique source-receiver pairs were acquired during this testing. In the second experiment, we reacquired aproximately 8,800 source-receiver pairs and performed a cross-line survey allowing for a 3D post-explosion Vp model. The data acquired from the reoccupied sites was processed using cross-correlation methods and change detection methodologies, including comparison of the tomographic images. The survey design and subsequent processing provided an opportunity to investigate seismic wave propagation through damaged rock. We also performed full waveform forward modelling for a granitic body hosting a perched aquifer. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

  11. UNDERSTANDING THE BREAST CANCER EXPERIENCE OF WOMEN: A QUALITATIVE STUDY OF AFRICAN AMERICAN, ASIAN AMERICAN, LATINA AND CAUCASIAN CANCER SURVIVORS

    PubMed Central

    ASHING-GIWA, KIMLIN TAM; PADILLA, GERALDINE; TEJERO, JUDITH; KRAEMER, JANET; WRIGHT, KAREN; COSCARELLI, ANNE; CLAYTON, SHEILA; WILLIAMS, IMANI; HILLS, DAWN

    2006-01-01

    Breast cancer is the most common form of cancer in American women across most ethnic groups. Although the psychosocial impact of breast cancer is being studied, there is little information on women from diverse ethnic and socioeconomic backgrounds. We conducted a qualitative study with breast cancer survivors (BCS) of various ethnicities. A total of 102 BCS participated in focus group interviews (24 African Americans, 34 Asians, 26 Latinas and 18 Caucasians); 20 health professionals participated in key informant interviews. Important ethnic differences in type of treatment were noted, Asians and Latinas were more likely to receive mastectomies and African American BCS were least likely to receive adjuvant therapies, including radiation and chemotherapy. These BCS enjoyed a fairly good overall health-related quality of life (HRQOL) with some persistent concerns. The prevailing concerns among all women included overall health, moderate physical concerns, cancer recurrence or metastases, psychosocial concerns related to worry about children and burdening the family, and body image and sexual health concerns. Additional challenges included: lack of knowledge about breast cancer; medical care issues such as insurance, cost and amount of time spent with physician; cultural sensitivity of providers, language barriers, cultural factors related to beliefs about illness, gender role and family obligations (e.g. self-sacrifice). These BCS, particularly the women of color, voiced that their spiritual beliefs and practices are central to their coping. This study accomplishes two goals; it adds to the sparse literature concerning the psychosocial sequelae of breast cancer among women of color, and it increases our knowledge of specific cultural influences (e.g. dietary practices, coping) and socio-ecological factors on HRQOL. More importantly, the study addressed areas that have not been studied before, specifically, an in-depth study on BCS QOL comparing multiple ethnic groups

  12. African American Preschoolers' Language, Emergent Literacy Skills, and Use of African American English: A Complex Relation

    ERIC Educational Resources Information Center

    Connor, Carol McDonald; Craig, Holly K.

    2006-01-01

    Purpose: This study examined the relation between African American preschoolers' use of African American English (AAE) and their language and emergent literacy skills in an effort to better understand the perplexing and persistent difficulties many African American children experience learning to read proficiently. Method: African American…

  13. Stress control of seismicity patterns observed during hydraulic fracturing experiments at the Fenton Hill hot dry rock geothermal energy site, New Mexico

    SciTech Connect

    Fehler, M.C.

    1987-04-13

    Seismicity accompanying hydraulic injections into granitic rock is often diffuse rather than falling along a single plane. This diffuse zone of seismicity cannot be attributed to systematic errors in locations of the events. It has often been asserted that seismicity occurs along preexisting joints in the rock that are favorably aligned with the stress field so that slip can occur along them when effective stress is reduced by increasing pore fluid pressure. A new scheme for determining orientations and locations of planes along which the microearthquakes occurred was recently developed. The basic assumption of the method, called the three point method, is that many of the events fall along well defined planes; these planes are often difficult to identify visually in the data because planes of many orientations are present. The method has been applied to four hydraulic fracturing experiments conducted at Fenton Hill as part of a hot dry rock geothermal energy project. While multiple planes are found for each experiment; one plane is common to all experiments. The ratio of shear to normal stress along planes of all orientations is calculated using a best estimate of the current stress state at Fenton Hill. The plane common to all experiments has the highest ratio of shear to normal stress acting along it, so it is the plane most likely to slip. The other planes found by the three point method all have orientations with respect to current principal stresses that are favorable for slip to occur along preexisting planes of weakness. These results are consistent with the assertion that the rock contains pre-existing joints which slip when the effective stress is reduced by the increased pore fluid pressure accompanying the hydraulic injection. Microearthquakes occur along those planes that are favorably aligned with respect to the current stress field.

  14. Experimenting in Distance Education: The African Virtual University (AVU) and the Paradox of the World Bank in Kenya

    ERIC Educational Resources Information Center

    Amutabi, M. N.; Oketch, M. O.

    2003-01-01

    This article seeks to accomplish three objectives. The first is to interrogate the efficacy of the African Virtual University (AVU), which is a satellite and information technology (IT)-based distance education system, sponsored by the World Bank in Kenya. The second is to demonstrate the failures of the AVU and the reasons why this has been the…

  15. From Victory to Freedom: The African American Experience. Curriculum Guide: Elementary and Middle School Course of Study.

    ERIC Educational Resources Information Center

    Ohio Historical Society, Columbus.

    This elementary and middle school curriculum guide contains three sections of instructional materials about three areas of African American life. The section "Community Life" includes detailed lessons on family, the church, education, business, and organizations. The section "Public Life" provides in-depth lessons on media, science and medicine,…

  16. The African Experience. Volume I: Syllabus Lectures; Volume II: Bibliographic References; Volume IIIA: Introductory Essays; Volume IIIB: Introductory Essays.

    ERIC Educational Resources Information Center

    Paden, John N.; Soja, Edward W.

    In response to demands for more and better teaching about Africa in American higher education, the US Office of Education requested that the Program of African Studies at Northwestern University generate a set of teaching materials which could be used in introductory undergraduate courses. Included in these volumes, these materials provide…

  17. Inclusive Education and Training in South African Higher Education: Mapping the Experiences of a Student with Physical Disability at University

    ERIC Educational Resources Information Center

    Ntombela, Sithabile

    2013-01-01

    The South African Constitution upholds and entrenches the human right of all citizens. Similarly, the Higher Education Act of 1997 promotes equality of access for all, especially for those previously marginalised or excluded. The study reported in this article explored challenges experienced by students with disabilities at his university. Using…

  18. Ethnic Identity, Neighborhood Risk, and Adolescent Drug and Sex Attitudes and Refusal Efficacy: The Urban African American Girls' Experience

    ERIC Educational Resources Information Center

    Corneille, Maya A.; Belgrave, Faye Z.

    2007-01-01

    This study examined the impact of ethnic identity and neighborhood risk on drug and sex attitudes and refusal efficacy among early adolescent urban African American females (n = 175). The model also predicted a moderating relationship of ethnic identity on neighborhood risk for drug and sex attitudes and refusal efficacy. Data were collected as…

  19. Interactive Reading Experiences of African American Fathers and Social Fathers and Their 4- and 5-Year-Old Children

    ERIC Educational Resources Information Center

    Jackson, Clarissa R.

    2012-01-01

    The purpose of this mixed-methods study was to investigate the patterns of book choice and interaction during book reading sessions of six African American fathers and social fathers and their 4- to 5-year-old children. The fathers/social fathers selected and read aloud expository text, narrative text, and poetry to their children while…

  20. Building the Capacity of First Year Social Work Students: Experiences from a South African Tertiary Education Institution

    ERIC Educational Resources Information Center

    Drower, Sandra J.; Kleijn, Amelia A.

    2008-01-01

    A three part Building Capacity Program developed for social work students in a South African tertiary education institution is described. The primary purpose of the Program was to build the capacity of social work students considered to be at risk of not completing their studies. The Program is located within the socio-political context of South…

  1. Retaining and Reclaiming Ourselves: Reflections on a Peer Mentoring Group Experience for New African American Women Professors

    ERIC Educational Resources Information Center

    Packer-Williams, Catherine L.; Evans, Kathy M.

    2011-01-01

    This article reports on the results of a qualitative study of new African American female professors' participation in a peer mentoring group. Three key themes that emerged from the data included peer mentoring as a vehicle to process and cope effectively with microaggressions, increase positive self-identity and self-efficacy as a scholar, and…

  2. A Peculiar Sensation: Double Consciousness and the Lived Experiences of African American Art Historians at Predominately White Institutions

    ERIC Educational Resources Information Center

    Swaidan, Christina Michelle

    2010-01-01

    Double consciousness is the identity conflict of being Black and being an American (Du Bois, 1903). Double consciousness leads to "identity confusion and inherent contradictions in the collective psyche of people of African descent" (Benjamin, 2005, p. 21.). This study employed grounded theory to collect and analyze the data that emerged from the…

  3. Executive University Managers' Experiences of Strike and Protest Activity: A Qualitative Case Study of a South African University

    ERIC Educational Resources Information Center

    Dominguez-Whitehead, Y.

    2011-01-01

    Strike and protest activity at South African universities continues to be prevalent nearly two decades after the dismantling of apartheid, although there has been a shift away from directing strikes and protests against the government (during the apartheid era), to directing them against higher education institutions and management (since the…

  4. Narratives of Agency: The Experiences of Braille Literacy Practitioners in the "Kha Ri Gude" South African Mass Literacy Campaign

    ERIC Educational Resources Information Center

    McKay, Veronica I.; Romm, Norma R. A.

    2015-01-01

    In this article, we locate the "Kha Ri Gude" South African Mass Literacy Campaign within the context of the problem of illiteracy and exclusion in South Africa, while concentrating on various post-apartheid initiatives designed to give visually challenged adults the opportunity to become literate. We shall provide a detailed account of…

  5. Detecting weak seismicity in urban areas using waveform stacking and cross correlation: Application to a stimulation experiment

    NASA Astrophysics Data System (ADS)

    Plenkers, K.; Ritter, J.; Schindler, M.

    2012-04-01

    Urban noise often prevents the detection of microseismicity (ML < 2). The problem is well known from many geotechnical production sites, where the need to perform reliable hazard assessment has increased the interest in small seismic events. We study the microseismicity (ML < 2) in the region of Landau, SW Germany. Here, due to thick sediments ( approx. 3 km) and high cultural seismic noise, the signal-to-noise ratio is in general very low for small earthquakes. To gain new insights into the occurrence of very small seismic events we developed a 3-step detection approach and are thus able to identify 207 formerly unknown microseismic events (-1 < ML < 1) with signal-to-noise ratios smaller than three. We use the recordings from a unfavourable broadband network installed for a teleseismic study with station distances of approximately 10 km. First, we apply a short term average to long term average detection algorithm for data reduction. The detection algorithm is affected severely by transient noise signals that do not differ in frequency content, duration and amplitude from the microseismic events searched for. Therefore, the most promising detections, selected by coinciding triggers and high amplitude measures, are reviewed manually. In this way we are able to identify 13 seismic events. Finally, we conduct a cross correlation analysis. As master template we use the stacked waveforms of five manually detected seismic events with a repeating waveform. This search reveals additional 194 events with a cross correlation coefficient exceeding 0.65 which ensures a stable identification. Our analysis shows that the repeating events occurred during the stimulation of a geothermal reservoir within a source region of only about (0.5 km)3.

  6. Technical Consulting: The African-American Perspective

    ERIC Educational Resources Information Center

    Whitfield, Tracy N.

    2010-01-01

    The qualitative research study explored the organizational characteristics necessary in addressing the low concentration of African American technical consultants employed in the information technology industry. Using research participants' professional experience, participants responded to a developed questionnaire. African American technical…

  7. Cooperation between scientists, NGOs and industry in support of sustainable fisheries: the South African hake Merluccius spp. trawl fishery experience.

    PubMed

    Field, J G; Attwood, C G; Jarre, A; Sink, K; Atkinson, L J; Petersen, S

    2013-10-01

    This paper examines the increasingly close interaction between natural and social scientists, non-governmental organizations (NGO) and industry, in pursuit of responsible ecosystem-based management of fisheries. South Africa has committed to implementing an ecosystem approach to fisheries management. Management advice stems from multi-stakeholder representation on government-led scientific and management working groups. In the hake Merluccius capensis and Merluccius paradoxus fishery, the primary management measure is an annual total allowable catch (TAC), the level of which is calculated using a management procedure (MP) that is revised approximately every 4 years. Revision of the MP is a consultative process involving most stakeholders, and is based on simulation modelling of projected probable scenarios of resource and fishery dynamics under various management options. NGOs, such as the Worldwide Fund for Nature in South Africa (WWF-SA), have played an important role in influencing consumers, the fishing industry and government to develop responsible fishing practices that minimize damage to marine ecosystems. Cooperation between industry, government and scientists has helped to improve sustainability and facilitated the meeting of market-based incentives for more responsible fisheries. Research includes ecosystem modelling, spatial analysis and ecosystem risk assessment with increasing research focus on social and economic aspects of the fishery. A four-year cooperative experiment to quantify the effect of trawling on benthic community structure is being planned. The food requirements of top predators still need to be included in the TAC-setting formulae and more social and economic research is needed. This paper also demonstrates how NGO initiatives such as Marine Stewardship Council certification and the Southern African Sustainable Seafood Initiative, a traffic light system of classifying seafood for consumers, have contributed to responsible fishing

  8. Towards 4-D Noise-based Seismic Probing of Volcanoes: Perspectives from a Large-N Nodal Experiment on Piton de la Fournaise Volcano

    NASA Astrophysics Data System (ADS)

    Brenguier, F.; Ackerley, N. J.; Nakata, N.; Boué, P.; Campillo, M.; Roux, P.; Shapiro, N.

    2015-12-01

    Noise-based seismology is proving to be a complementary approach to active source or earthquake-based methods for imaging and monitoring the Earth's interior and in particular volcanoes and active faults. Until recently, noise-based imaging and monitoring relied only on the inversion of surface waves reconstructed from correlations of mostly microseismic seismic noise. Compared to body-wave tomography, surface wave tomography succeeds in retrieving lateral sub-surface velocity contrasts but is less efficient in resolving velocity perturbations at depth. Moreover reflected body-waves can carry direct information about sharp interfaces at depth. Extracting body-waves from noise correlations is challenging and the use of Large-N seismic arrays proves to be of great benefit for extracting noisy body-waves from noise-correlations by stacking over a large number of receiver pairs and by applying array processing. The purpose of VolcArray Large-N seismic experiment on Piton de la Fournaise Volcano is to extract body-waves travelling directly through the active magma reservoir located at ~2.5 km depth below the summit crater using noise correlations between arrays of seismic nodes. By beamforming noise on individual arrays, we found an unusual strong directional source of body-wave noise. This is thus a favorable context for retrieving the body-wave component of the Green's function between arrays. However, standard correlation techniques between nodes do not allow deciphering between the reconstructed Green's function and artifacts from the correlation of the strong directional source of body-waves. By applying double beamforming to the noise correlations between arrays, we are able to isolate ballistic body-waves travelling across the magma storage zone at depth. The stability of these reconstructed waves over time is encouraging in the perspectives of high resolution monitoring of the volcano feeding system.

  9. Using climate model experiments to explore difference between degrees of global warming: lessons from a study of African precipitation

    NASA Astrophysics Data System (ADS)

    James, Rachel; Washington, Richard

    2015-04-01

    A 2°C increase in global mean temperature (ΔTg) has been widely adopted as a benchmark for dangerous climate change, and is currently being reviewed under the United Nations Framework Convention on Climate Change. However, there has been relatively little research into the implications of 2°C, or any other degree of global warming, for regional climate. This lack of research is particularly pressing in the case of vulnerable regions, including many in Africa. In recognition of this research gap, we conducted an in depth study of changes in African temperature and precipitation associated with 1°C, 1.5°C, 2°C, 3°C, 4°C, and beyond, using output from almost 400 climate model experiments: simulations from international modelling centres (CMIP3 and CMIP5), two perturbed physics ensembles, and a group of five regional models. The implications of global warming are different depending on which models are consulted, but each model consistently shows that temperature and precipitation anomalies are enhanced progressively with global warming. At 1°C, there is little significant change, but from 1.5°C or 2°C anomalies develop which grow in magnitude and spatial extent with global temperature, for example drying over Angola, and wetting in East Africa. The main difference between ΔTg intervals is in the magnitude and spatial extent of change. There do not appear to be rapid accelerations in the rate of change or trend reversals. This is not only true for lower levels of anthropogenic forcing, but also at higher degrees of warming up to 6°C. This finding has potential implications for policy. Given that larger changes in climate are likely to generate greater challenges for society, it suggests that global temperature should be limited to the lowest level possible. It does not imply that 2°C, or any other ΔTg increment, should be a preferred target from the perspective of regional climate. However, it is important to consider whether the approximately linear

  10. Alignment silkworms as seismic animal anomalous behavior (SAAB) and electromagnetic model of a fault: a theory and laboratory experiment

    NASA Astrophysics Data System (ADS)

    Ikeya, Motoji; Matsumoto, Hiroshi; Huang, Qing-Hua

    1998-05-01

    Alignment of silkworms and fish, observed as seismic anomalous animal behavior (SAAB) prior to the Kobe earthquake, were duplicated in a laboratory by applying a pulsed electric field assuming SAAB as electrophysiological responses to the stimuli of seismic electric signals (SES). The animals became aligned perpendicularly to the field direction since their skeletal muscle had a higher resistivity perpendicular to the field direction than parallel to it. An electromagnetic model of a fault is proposed in which dipolar charges, ±q are generated due to the change of seismic stress, σ(t). From a mathematical model, dq/dt=-α(dσ/dt) - q/ɛρ, where α is the charge generation constant like a piezoelectric coefficient, ɛ, the dielectric constant and ρ, the resistivity of bedrock granite. A fault having a length 2a and a displacement or rock rupture time τ, during which the stress is changed, gives pulsed dipolar charge surface densities, +q(t, x) and -q(t, x+2a), or an apparent electric dipole moment of P(t)=2aQ(t)=2aAq(t)=aM 0[ɛρ/(τ-ɛρ)](e-1/τ-e-1/σρ) using the earthquake moment M 0. The fault displacement, D, its initial velocity, D‧ and the stress drop, Δσ give τ=D/D‧=(Δσ/σ 0)(α/β). The field fintensity, F, and seismic current density at a fault zone, J were calculated as F=q/ɛ and J=F/ρ‧ using ρ‧ of water as to give J=0.1-1 A/m2 sufficient to cause SAAB experimentally. The near-field ultra low frequency (ULF) waves generated by P(t) give SES reciprocally proportional to the distance R.

  11. Seismic Ecology

    NASA Astrophysics Data System (ADS)

    Seleznev, V. S.; Soloviev, V. M.; Emanov, A. F.

    The paper is devoted to researches of influence of seismic actions for industrial and civil buildings and people. The seismic actions bring influence directly on the people (vibration actions, force shocks at earthquakes) or indirectly through various build- ings and the constructions and can be strong (be felt by people) and weak (be fixed by sensing devices). The great number of work is devoted to influence of violent seismic actions (first of all of earthquakes) on people and various constructions. This work is devoted to study weak, but long seismic actions on various buildings and people. There is a need to take into account seismic oscillations, acting on the territory, at construction of various buildings on urbanized territories. Essential influence, except for violent earthquakes, man-caused seismic actions: the explosions, seismic noise, emitted by plant facilities and moving transport, radiation from high-rise buildings and constructions under action of a wind, etc. can exert. Materials on increase of man- caused seismicity in a number of regions in Russia, which earlier were not seismic, are presented in the paper. Along with maps of seismic microzoning maps to be built indicating a variation of amplitude spectra of seismic noise within day, months, years. The presence of an information about amplitudes and frequencies of oscillations from possible earthquakes and man-caused oscillations in concrete regions allows carry- ing out soundly designing and construction of industrial and civil housing projects. The construction of buildings even in not seismically dangerous regions, which have one from resonance frequencies coincident on magnitude to frequency of oscillations, emitted in this place by man-caused objects, can end in failure of these buildings and heaviest consequences for the people. The practical examples of detail of engineering- seismological investigation of large industrial and civil housing projects of Siberia territory (hydro power

  12. Delineating Crustal Deformation by Onshore/Offshore Seismic Experiments in the Backstop Region of the Mediterranean Ridge

    NASA Astrophysics Data System (ADS)

    Papoulia, J. E.; Makris, J.

    2009-12-01

    In order to define the velocity structure of the crust and the sedimentary basins offshore western Peloponnese,we observed 5 seismic profiles. We used 65 4-Component Ocean Bottom Seismographs (OBS) and spaced them inline at 3 Km intervals. Line lengths varied between 60 and 180 Km. Four lines were oriented perpendicular to the coast (NE-SW orientation) and one parallel to it (NW-SE orientation) crossing three out of four NE-SW lines. The seismic energy was generated by a tuned 42 l air gun array that was fired at 125 m intervals. The evaluation procedure of the velocity modeling followed the sequence: First break tomography, layered tomography, forward modeling by two-point ray tracing and finally the Common Station Gathers were depth migrated using the velocity models. In this way we were able to develop the geometry of the crust and sediments and also map the major faults. The crust in the complete area is continental ranging between 27 Km in the north (island of Zakynthos), and 22 to 24 Km in the Kyparissiakos and Messiniakos gulfs to the south. Sedimentary thickness in these basins is significant and in the order of 8 to 10 Km. The “backstop” area that extends to the eastern limit of the Mediterranean Ridge is floored by thinned continental crust of about 20 Km, thickening to about 22 Km to the east. The sediments here are less thick and vary between 5 and 7 Km. Oceanic crust was mapped only along the western part of the two southern lines, beyond the backstop limit, under the Mediterranean Ridge. In the oceanic domain crustal thickness is about 16 Km in water depth of nearly 4 Km. The down dipping of the oceanic layer at the beginning of the subduction has strong reflectivity and clearly marks the border of the continental to the oceanic domains. The Preapulian zone is exposed on Zakynthos and the Strophades islands that tectonically build large thrusts and define the western limit of the offshore folded Ionian zone. High velocity limestone marking the

  13. Seismic reflection data imaging and interpretation from Braniewo2014 experiment using additional wide-angle refraction and reflection and well-logs data

    NASA Astrophysics Data System (ADS)

    Trzeciak, Maciej; Majdański, Mariusz; Białas, Sebastian; Gaczyński, Edward; Maksym, Andrzej

    2015-04-01

    Braniewo2014 reflection and refraction experiment was realized in cooperation between Polish Oil and Gas Company (PGNiG) and the Institute of Geophysics (IGF), Polish Academy of Sciences, near the locality of Braniewo in northern Poland. PGNiG realized a 20-km-long reflection profile, using vibroseis and dynamite shooting; the aim of the reflection survey was to characterise Silurian shale gas reservoir. IGF deployed 59 seismic stations along this profile and registered additional full-spread wide-angle refraction and reflection data, with offsets up to 12 km; maximum offsets from the seismic reflection survey was 3 km. To improve the velocity information two velocity logs from near deep boreholes were used. The main goal of the joint reflection-refraction interpretation was to find relations between velocity field from reflection velocity analysis and refraction tomography, and to build a velocity model which would be consistent for both, reflection and refraction, datasets. In this paper we present imaging results and velocity models from Braniewo2014 experiment and the methodology we used.

  14. Experiences of Discrimination and Their Impact on the Mental Health Among African American, Asian and Pacific Islander, and Latino Men Who Have Sex With Men

    PubMed Central

    Paul, Jay; Ayala, George; Boylan, Ross; Gregorich, Steven E.

    2013-01-01

    Objectives. We examined the associations between specific types and sources of discrimination and mental health outcomes among US racial/ethnic minority men who have sex with men (MSM) and how these associations varied by race/ethnicity. Methods. A chain-referral sample of 403 African American, 393 Asian and Pacific Islander (API), and 400 Latino MSM recruited in Los Angeles County, California completed a standardized questionnaire. Data were obtained from the Ethnic Minority Men’s Health Study from May 2008 to October 2009. Results. Past-year experiences of racism within the general community and perceived homophobia among heterosexual friends were positively associated with depression and anxiety. Past-year homophobia experienced within the general community was also positively associated with anxiety. These statistically significant associations did not vary across racial/ethnic groups. The positive association of perceived racism within the gay community with anxiety differed by race/ethnicity, and was statistically significant only for APIs. Perceived homophobia within the family was not associated with either depression or anxiety. Conclusions. Higher levels of experiences of discrimination were associated with psychological distress among MSM of color. However, specific types and sources of discrimination were differentially linked to negative mental health outcomes among African American, API, and Latino MSM. PMID:23488483

  15. EXPERIENCES OF HIV/AIDS STIGMA OF PERSONS LIVING WITH HIV/AIDS AND NURSES INVOLVED IN THEIR CARE FROM FIVE AFRICAN COUNTRIES

    PubMed Central

    Greeff, Minrie; Uys, Leana R; Holzemer, William L; Makoae, Lucia N; Dlamini, Priscilla S; Kohi, Thecla W; Chirwa, Maureen L; Naidoo, Joanne R; Phetlhu, Rene D.

    2009-01-01

    The concept of stigma has received significant attention in recent years in the HIV/AIDS literature. Although there is some change towards the positive, AIDS still remains a significantly stigmatized condition. AIDS stigma and discrimination continue to influence people living with and affected by HIV (PLWA), as well as their health-care providers. Unless stigma is conquered, the illness will not be defeated. Due to the burden that HIV/AIDS places on people living in Africa, a five-year project entitled Perceived AIDS Stigma: A Multinational African Study was undertaken. The focus of the first phase of this project was on exploring and describing the meaning and effect of stigma on PLWA from the experiences of PLWA and the nurses involved in their care in five African countries: Lesotho, Swaziland, Malawi, South Africa and Tanzania. An exploratory descriptive qualitative research design was used to explore and describe the experience of stigma through the critical incident method. Purposive voluntary sampling was utilized. Forty-three focus group discussions were held with respondents to relate incidences which they themselves observed, as well as those that they themselves experienced in the community and in families. The transcribed data was analyzed through the technique of open coding using the NVivo 2.0 analysis package. Three types of stigma (received stigma, internal stigma and associated stigma) and several dimensions for each of these types of stigma emerged from the data. Recommendations were made to pursue these findings further. PMID:20052299

  16. EXPERIENCES OF HIV/AIDS STIGMA OF PERSONS LIVING WITH HIV/AIDS AND NURSES INVOLVED IN THEIR CARE FROM FIVE AFRICAN COUNTRIES.

    PubMed

    Greeff, Minrie; Uys, Leana R; Holzemer, William L; Makoae, Lucia N; Dlamini, Priscilla S; Kohi, Thecla W; Chirwa, Maureen L; Naidoo, Joanne R; Phetlhu, Rene D

    2008-01-01

    The concept of stigma has received significant attention in recent years in the HIV/AIDS literature. Although there is some change towards the positive, AIDS still remains a significantly stigmatized condition. AIDS stigma and discrimination continue to influence people living with and affected by HIV (PLWA), as well as their health-care providers. Unless stigma is conquered, the illness will not be defeated. Due to the burden that HIV/AIDS places on people living in Africa, a five-year project entitled Perceived AIDS Stigma: A Multinational African Study was undertaken. The focus of the first phase of this project was on exploring and describing the meaning and effect of stigma on PLWA from the experiences of PLWA and the nurses involved in their care in five African countries: Lesotho, Swaziland, Malawi, South Africa and Tanzania. An exploratory descriptive qualitative research design was used to explore and describe the experience of stigma through the critical incident method. Purposive voluntary sampling was utilized. Forty-three focus group discussions were held with respondents to relate incidences which they themselves observed, as well as those that they themselves experienced in the community and in families. The transcribed data was analyzed through the technique of open coding using the NVivo 2.0 analysis package. Three types of stigma (received stigma, internal stigma and associated stigma) and several dimensions for each of these types of stigma emerged from the data. Recommendations were made to pursue these findings further. PMID:20052299

  17. “It's The Skin You're In”: African-American Women Talk About Their Experiences of Racism. An Exploratory Study to Develop Measures of Racism for Birth Outcome Studies

    PubMed Central

    Nuru-Jeter, Amani; Dominguez, Tyan Parker; Hammond, Wizdom Powell; Leu, Janxin; Skaff, Marilyn; Egerter, Susan; Jones, Camara P.; Braveman, Paula

    2011-01-01

    Objectives Stress due to experiences of racism could contribute to African-American women's adverse birth outcomes, but systematic efforts to measure relevant experiences among childbearing women have been limited. We explored the racism experiences of childbearing African-American women to inform subsequent development of improved measures for birth outcomes research. Methods Six focus groups were conducted with a total of 40 socioeconomically diverse African-American women of childbearing age in four northern California cities. Results Women reported experiencing racism (1) throughout the lifecourse, with childhood experiences seeming particularly salient and to have especially enduring effects (2) directly and vicariously, particularly in relation to their children; (3) in interpersonal, institutional, and internalized forms; (4) across different life domains; (5) with active and passive responses; and (6) with pervasive vigilance, anticipating threats to themselves and their children. Conclusions This exploratory study's findings support the need for measures reflecting the complexity of childbearing African-American women's racism experiences. In addition to discrete, interpersonal experiences across multiple domains and active/passive responses, which have been measured, birth outcomes research should also measure women's childhood experiences and their potentially enduring impact, perceptions of institutionalized racism and internalized negative stereotypes, vicarious experiences related to their children, vigilance in anticipating future racism events, as well as the pervasiveness and chronicity of racism exposure, all of which could be sources of ongoing stress with potentially serious implications for birth outcomes. Measures of racism addressing these issues should be developed and formally tested. PMID:18463971

  18. Emergency preparedness activities during an ongoing seismic swarm: the experience of the 2011-2012 Pollino (Southern Italy) sequence

    NASA Astrophysics Data System (ADS)

    Masi, A.; Mucciarelli, M.; Chiauzzi, L.; De Costanzo, G.; Loperte, G.

    2012-04-01

    Facing natural disasters effects can be a very difficult task lacking suitable activities and tools to preventively prepare the involved community (people, authorities, professionals, …) to the expected events. Therefore, a suite of preventive actions should be carried out to mitigate natural risks, in particular working to reduce the territorial vulnerability with respect to the specific natural hazard at hand, and to increase people response capacity. In fact, building social capacity helps to increase the risk perception and the people capacity to adapt to and cope with natural hazards. Since October 2011 a seismic swarm is affecting the Pollino mountain range, Southern Italy. At present the sequence is still ongoing, with more than 500 events with M>1, at least 40 well perceived by the population and a maximum magnitude at 3.6. The area mainly affected by the seismic sequence includes 12 villages, with a total population of about 50.000 inhabitants and, according to the current seismic hazard map it has high seismicity level. Such area was hit by a magnitude Ml=5.7 event in 1998 that produced macroseismic intensity not higher that VII-VIII degree of MCS scale and caused one dead, some injured and widespread damage in at least six municipalities. During the sequence, the National Department of Civil Protection (DPC) and the Civil Protection of Basilicata Region decided to put in action some measures aimed at verifying and enhancing emergency preparedness. These actions have been carried out with a constant and fruitful collaboration among the main stakeholders involved (scientific community, local and national governmental agencies, civil protection volunteers, etc) trough the following main activities: 1. collaboration between scientific community and the local and national offices of Civil Protection especially in the relationship with local authorities (e.g. mayors, which are civil protection authorities in their municipality); 2. interaction between DPC

  19. seismicity and seismotectonics of Libya

    NASA Astrophysics Data System (ADS)

    Ben Suleman, abdunnur

    2015-04-01

    Libya, located at the central Mediterranean margin of the African shield, underwent many episodes of orogenic activity that shaped its geological setting. The present day deformation of Libya is the result of the Eurasia-Africa continental collision. The tectonic evolution of Libya has yielded a complex crustal structure that is composed of a series of basins and uplifts. This study aims to explain in detail the seismicity and seismotectonics of Libya using new data recorded by the recently established Libyan National Seismograph Network (LNSN) incorporating other available geophysical and geological information. Detailed investigations of the Libyan seismicity indicates that Libya has experienced earthquakes of varying magnitudes The seismic activity of Libya shows dominant trends of Seismicity with most of the seismic activity concentrated along the northern coastal areas. Four major clusters of Seismicity were quit noticeable. Fault plane solution was estimated for 20 earthquakes recorded by the Libyan National Seismograph Network in northwestern and northeastern Libya. Results of fault plane solution suggest that normal faulting was dominant in the westernmost part of Libya; strike slip faulting was dominant in northern-central part of Libya. The northern-eastern part of the country suggests that dip-dip faulting were more prevalent.

  20. Next-generation seismic experiments: wide-angle, multi-azimuth, three-dimensional, full-waveform inversion

    NASA Astrophysics Data System (ADS)

    Morgan, Joanna; Warner, Michael; Bell, Rebecca; Ashley, Jack; Barnes, Danielle; Little, Rachel; Roele, Katarina; Jones, Charles

    2013-12-01

    Full-waveform inversion (FWI) is an advanced seismic imaging technique that has recently become computationally feasible in three dimensions, and that is being widely adopted and applied by the oil and gas industry. Here we explore the potential for 3-D FWI, when combined with appropriate marine seismic acquisition, to recover high-resolution high-fidelity P-wave velocity models for subsedimentary targets within the crystalline crust and uppermost mantle. We demonstrate that FWI is able to recover detailed 3-D structural information within a radially faulted dome using a field data set acquired with a standard 3-D petroleum-industry marine acquisition system. Acquiring low-frequency seismic data is important for successful FWI; we show that current acquisition techniques can routinely acquire field data from airguns at frequencies as low as 2 Hz, and that 1 Hz acquisition is likely to be achievable using ocean-bottom hydrophones in deep water. Using existing geological and geophysical models, we construct P-wave velocity models over three potential subsedimentary targets: the Soufrière Hills Volcano on Montserrat and its associated crustal magmatic system, the crust and uppermost mantle across the continent-ocean transition beneath the Campos Basin offshore Brazil, and the oceanic crust and uppermost mantle beneath the East Pacific Rise mid-ocean ridge. We use these models to generate realistic multi-azimuth 3-D synthetic seismic data, and attempt to invert these data to recover the original models. We explore resolution and accuracy, sensitivity to noise and acquisition geometry, ability to invert elastic data using acoustic inversion codes, and the trade-off between low frequencies and starting velocity model accuracy. We show that FWI applied to multi-azimuth, refracted, wide-angle, low-frequency data can resolve features in the deep crust and uppermost mantle on scales that are significantly better than can be achieved by any other geophysical technique, and

  1. The Experience of Antiretroviral Treatment for Black West African Women who are HIV Positive and Living in London: An Interpretative Phenomenological Analysis.

    PubMed

    Spiers, Johanna; Smith, Jonathan A; Poliquin, Elizabeth; Anderson, Jane; Horne, Rob

    2016-09-01

    Antiretroviral therapy (ART) offers a powerful intervention in HIV but effectiveness can be compromised by inadequate adherence. This paper is a detailed examination of the experience of medication in a purposively selected group of people living with HIV. In-depth interviews were conducted with 10 HIV positive, West African women of black heritage living in London, UK. This group was of interest since it is the second largest group affected by HIV in the UK. Interviews were subjected to interpretative phenomenological analysis, an idiographic, experiential, qualitative approach. The paper details the women's negative experience of treatment. ART can be considered difficult and unrelenting and may be disconnected from the women's sense of health or illness. Participants' social context often exacerbated the difficulties. Some reported an improvement in their feelings about the medication over time. These findings point to some intrinsic and social motivators which could act as spurs to adherence. PMID:26767539

  2. Crustal thickness and velocity structure across the Moroccan Atlas from long offset wide-angle reflection seismic data: The SIMA experiment

    NASA Astrophysics Data System (ADS)

    Ayarza, P.; Carbonell, R.; Teixell, A.; Palomeras, I.; Martí, D.; Kchikach, A.; Harnafi, M.; Levander, A.; Gallart, J.; Arboleya, M. L.; Alcalde, J.; Fernández, M.; Charroud, M.; Amrhar, M.

    2014-05-01

    crustal structure and topography of the Moho boundary beneath the Atlas Mountains of Morocco has been constrained by a controlled source, wide-angle seismic reflection transect: the SIMA experiment. This paper presents the first results of this project, consisting of an almost 700 km long, high-resolution seismic profile acquired from the Sahara craton across the High and the Middle Atlas and the Rif Mountains. The interpretation of this seismic data set is based on forward modeling by raytracing, and has resulted in a detailed crustal structure and velocity model for the Atlas Mountains. Results indicate that the High Atlas features a moderate crustal thickness, with the Moho located at a minimum depth of 35 km to the S and at around 31 km to the N, in the Middle Atlas. Upper crustal shortening is resolved at depth through a crustal root where the Saharan crust underthrusts the northern Moroccan crust. This feature defines a lower crust imbrication that, locally, places the Moho boundary at ˜40-41 km depth in the northern part of the High Atlas. The P-wave velocity model is characterized by relatively low velocities, mostly in the lower crust and upper mantle, when compared to other active orogens and continental regions. These low deep crustal velocities together with other geophysical observables such as conductivity estimates derived from MT measurements, moderate Bouguer gravity anomaly, high heat flow, and surface exposures of recent alkaline volcanism lead to a model where partial melts are currently emplaced at deep crustal levels and in the upper mantle. The resulting model supports the existence of a mantle upwelling as mechanism that would contribute significantly to sustain the High Atlas topography. However, the detailed Moho geometry deduced in this work should lead to a revision of the exact geometry and position of this mantle feature and will require new modeling efforts.

  3. Deep seismic reflection data of EDGE U.S. mid-Atlantic continental-margin experiment: Implications for Appalachian sutures and Mesozoic rifting and magmatic underplating

    NASA Astrophysics Data System (ADS)

    Sheridan, Robert E.; Musser, Douglas L.; Glover, Lynn, III; Talwani, Manik; Ewing, John I.; Holbrook, W. Steven; Purdy, G. Michael; Hawman, Robert; Smithson, Scott

    1993-06-01

    The EDGE seismic experiment across the Virginia continental margin delineated a Paleozoic suture, buried Appalachian terranes, and Mesozoic rifting and magmatic events. The seismic grid revealed that the Mesozoic Norfolk rift basin exists only in the northern one-third of the previously mapped area. The north-striking listric border fault of the Norfolk basin half-graben parallels seismic laminations in the basement. The Jurassic volcanic wedge pinches out just landward of the Baltimore Canyon trough hinge zone and downlaps on the hummocky oceanic basement under the continental rise. Under the continental slope, the volcanic wedgereaches depths >9 s (20 km). Two distinct intracrustal reflections at 4.0-5.0 s and at 7.0 s TWIT (two-way traveltime) dip southeastward at low angles (˜15°). The Moho reflection is disrupted where it is intersected by the 7.0 s reflection. Northwest of this point the Moho dips landward; seaward it is horizontal. Seaward of this point, the lower-crustal boundary laminations exist in a narrow interval (10.5-11.0 s) and are of strong amplitude. These changes in the Moho and lower crust represent the seaward edge of the Grenville-age North American crust and the landward edge of Jurassic magmatic underplating. A northwest-dipping reflection observed for the first time on the U.S. Atlantic margin may be the top of the Jurassic magmatic- underplating layer; the northwest-dipping reflection truncates the southeast- dipping 7.0 s TWTT reflection. Landward projection of the 7.0 s reflection yields a north-south trace on the postrift unconformity under the center of lower Chesapeake Bay. This trace is near a basement fault between low-grade metamorphic rocks (Carolina slate-Avalonia) on the east and high-grade rocks (Goochland terrane) on the west. This fault boundary and the southeastdipping 7.0 s reflection probably represent the Taconic suture.

  4. Lower Crustal Seismicity, Volatiles, and Evolving Strain Fields During the Initial Stages of Cratonic Rifting

    NASA Astrophysics Data System (ADS)

    Lambert, C.; Muirhead, J.; Ebinger, C. J.; Tiberi, C.; Roecker, S. W.; Ferdinand-Wambura, R.; Kianji, G.; Mulibo, G. D.

    2014-12-01

    The volcanically active East African rift system in southern Kenya and northern Tanzania transects thick cratonic lithosphere, and comprises several basins characterized by deep crustal seismicity. The US-French-Tanzania-Kenya CRAFTI project aims to understand the role of magma and volatile movement during the initiation and evolution of rifting in cratonic lithosphere. Our 38-station broadband network spans all or parts of fault-bounded rift segments, enabling comparison of lithospheric structure, fault kinematics, and seismogenic layer thickness with age and proximity to the deeply rooted Archaen craton. Seismicity levels are high in all basins, but we find profound differences in seismogenic layer thickness along the length of the rift. Seismicity in the Manyara basin occurs almost exclusively within the lower crust, and in spatial clusters that have been active since 1990. In contrast, seismicity in the ~ 5 My older Magadi basin is localized in the upper crust, and the long border fault bounding the west side of the basin is seismically inactive. Between these two basins lies the Natron rift segment, which shows seismicity between ~ 20 and ~2 km depth, and high concentrations at Oldoinyo Lengai and Gelai volcanoes. Older volcanoes on the uplifted western flank (e.g., Ngorongoro) experience swarms of activity, suggesting that active magmatism and degassing are widespread. Focal mechanisms of the frequent earthquakes recorded across the array are spatially variable, and indicate a stress field strongly influenced by (1) Holocene volcanoes, (2) mechanical interactions between adjacent rift basins, and (3) a far-field ESE-WNW extensional stress regime. We explore the spatial correlation between zones of intense degassing along fault systems and seismicity, and examine the influence of high gas pressures on lower and upper crustal seismicity in this youthful cratonic rift zone.

  5. The SOUTHERN PUNA Seismic Experiment: Shape of the Subducting Nazca Plate, Areas of Concentrated Mantle and Crustal Earthquakes, and Crustal Focal Mechanisms

    NASA Astrophysics Data System (ADS)

    Mulcahy, P.; Chen, C.; Kay, S. M.; Brown, L. D.; Alvarado, P. M.; Sandvol, E. A.; Heit, B.; Yuan, X.

    2010-12-01

    The SOUTHERN PUNA Seismic Experiment in the Central Andes between 25° - 28°S and 70° - 65°W recorded data in a 74-instrument array from Dec 07 to Nov 09 with the purpose of evaluating the structure and seismic character of the mantle and crust at the southern end of the Puna-Antiplano Plateau. Hypocenter locations for local and regional mantle earthquakes from 16 months of continuous recording confirm the persistence of the backarc teleseismic Antofalla Gap in intermediate depth mantle seismicity between 25.5° and 27.5°S consistent with the interpretation of a hot mantle wedge under this region. The best located Wadati Benioff Zone events agree with the subducting Nazca Plate contours of Cahill and Isacks (1992) north of 27°S, but show a more abrupt southward shallowing of contours in agreement with the Anderson et al. (2007) contours outlining the projected path of the already subducted Juan Fernandez Ridge. Another prominent feature in the data is the concentration of hypocenters in the Pipanaco nest to the south of the Antofalla Gap between 27° and 29°S. New PUNA results together with available HCMT solutions indicate NW oriented normal and strike-slip faulting in three general clusters within this nest at ~130km, 150km and 180km depth. Hypocenter locations and fault solutions for the Pipanaco Nest suggest flexure associated with steepening of the subducting slab consistent with the revised Wadati Benioff Zone contours. In an area of little to no crustal seismicity in global catalogs over the same time period, hundreds of well-located crustal earthquakes at depths less than 15km were recorded by the PUNA array. Among these earthquakes are three distinct clusters near relatively young volcanic centers. One cluster defines a nest northeast of the < 1 Ma Cerro Blanco caldera. The other two clusters are characterized by large quantities of earthquakes within 24-36 hours (swarms) near the Cerro Galan caldera that last erupted at ~2 Ma and near a ~1 Ma or

  6. Dynamic Assessment of Seismic Risk (DASR) by Multi-parametric Observations: Preliminary Results of PRIME experiment within the PRE-EARTHQUAKES EU-FP7 Project

    NASA Astrophysics Data System (ADS)

    Tramutoli, V.; Inan, S.; Jakowski, N.; Pulinets, S. A.; Romanov, A.; Filizzola, C.; Shagimuratov, I.; Pergola, N.; Ouzounov, D. P.; Papadopoulos, G. A.; Parrot, M.; Genzano, N.; Lisi, M.; Alparlsan, E.; Wilken, V.; Tsybukia, K.; Romanov, A.; Paciello, R.; Zakharenkova, I.; Romano, G.

    2012-12-01

    The integration of different observations together with the refinement of data analysis methods, is generally expected to improve our present knowledge of preparatory phases of earthquakes and of their possible precursors. This is also the main goal of PRE-EARTHQUAKES (Processing Russian and European EARTH observations for earthQUAKE precursors Studies) the FP7 Project which, to this aim, committed together, different international expertise and observational capabilities, in the last 2 years. In the learning phase of the project, different parameters (e.g. thermal anomalies, total electron content, radon concentration, etc.), measured from ground and satellite systems and analyzed by using different data analysis approaches, have been studied for selected geographic areas and specific seismic events in the past. Since July 2012 the PRIME (PRE-EARTHQUAKES Real-time Integration and Monitoring Experiment) started attempting to perform, on the base of independent observations collected and integrated in real-time through the PEG (PRE-EARTHQUAKES Geo-portal), a Dynamic Assessment of Seismic Risk (DASR) on selected geographic areas of Europe (Italy-Greece-Turkey) and Asia (Kamchatka, Sakhalin, Japan). In this paper, results so far achieved as well as the potential and opportunities they open for a worldwide Earthquake Observation System (EQuOS) - as a dedicated component of GEOSS (Global Earth Observation System of Systems) - will be presented.

  7. SinoProbe-02:Deep Seismic Reflection Profile (480km) experiment in North China:Acquisition and the Preliminary Processing result

    NASA Astrophysics Data System (ADS)

    Hou, H.; Gao, R.; Li, Q.; Li, W.; Kuang, Z.; Liu, J.; Zhang, J.; Guan, Y.; Keller, G.; Liu, M.; Cox, C. M.; Holloway, S.; Chang, J. C.; Kaip, G. M.; Zhang, S.

    2010-12-01

    An active-source deep seismic reflection experiment was recorded across the Central Asian and Trans-North China orogens (see Figure) last winter as part of the SinoProbe-02 program. This profile extended southeastward from Erenhot and ended in the Huailai basin near Beijing. The shot depth was 25m; the shot size was 30-50kg; and the nominal shot interval was 250 km. Additional 200-kg charges were set off every 1 km and 1 ton shots were placed at intervals of 50 km. A Sercel 408 XL recording system and 2000 strings of SM-24 geophones were deployed at a spacing of 50m. Recording was at a 2ms sample interval for a total of 30s.The typical processing stream included crooked-line binning, refraction statics, true amplitude recovery, deconvolution, detailed velocity analyses, residual statics corrections and NMO stack (see Table). To the south, a transparent granite body is indicated in the middle crust with a series of north dipping reflections structures in the lower crust. The complex structures near Sonid Youqi suggest a transparent crust due to the Solonker suture zone. Map showing deep seismic reflection profile (solid black line) across North China. Processing Parameters

  8. "Give a Brotha a Break!": The Experiences and Dilemmas of Middle-Class African American Male Students in White Suburban Schools

    ERIC Educational Resources Information Center

    Gordon, Beverly M.

    2012-01-01

    Background/Context: Today, in the era of the first African American president, approximately one third of all African Americans live in suburban communities, and their children are attending suburban schools. Although most research on the education of African American students, particularly males, focuses on their plight in urban schooling, what…

  9. Oncology pharmacy units: a safety policy for handling hazardous drugs and related waste in low- and middle-income African countries—Angolan experience

    PubMed Central

    da Conceição, Ana Vaz; Bernardo, Dora; Lopes, Lygia Vieira; Miguel, Fernando; Bessa, Fernanda; Monteiro, Fernando; Santos, Cristina; Oliveira, Blasques; Santos, Lúcio Lara

    2015-01-01

    In African countries, higher rates of late-stage cancers at the time of first diagnosis are a reality. In this context, hazardous drugs (HDs), such as chemotherapy, play an important role and have immense benefits for patients’ treatment. HDs should be handled under specific conditions. At least a class 5 environment primary engineering control (PEC), physically located in an appropriate buffer area, is mandatory for sterile HDs compounding, as well as administrative control, personal protective equipment, work practices and other engineering and environmental controls, in order to protect the environment, patient, and worker. The aim of this study is to describe the Angolan experience regarding the development of oncology pharmacy units and discuss international evidence-based guidelines on handling HDs and related waste. Measures to incorporate modern and economical solutions to upgrade or build adequate and safe facilities and staff training, in order to comply with international guidelines in this area, are crucial tasks for African countries of low and middle income. PMID:26557873

  10. Lithospheric structures and Precambrian terrane boundaries in northeastern Botswana revealed through magnetotelluric profiling as part of the Southern African Magnetotelluric Experiment

    NASA Astrophysics Data System (ADS)

    Miensopust, M. P.; Jones, A. G.; Muller, M. R.; Garcia, X.; Evans, R. L.

    2011-02-01

    Within the framework of the Southern African Magnetotelluric Experiment a focused study was undertaken to gain improved knowledge of the lithospheric geometries and structures of the westerly extension of the Zimbabwe craton (ZIM) into Botswana, with the overarching aim of increasing our understanding of southern African tectonics. The area of interest is located in northeastern Botswana, where Kalahari sands cover most of the geological terranes and very little is known about lithospheric structures and thicknesses. Some of the regional-scale terrane boundary locations, defined based on potential field data, are not sufficiently accurate for local-scale studies. Investigation of the NNW-SSE orientated, 600 km long ZIM line profile crossing the Zimbabwe craton, Magondi mobile belt, and Ghanzi-Chobe belt showed that the Zimbabwe craton is characterized by thick (˜220 km) resistive lithosphere, consistent with geochemical and geothermal estimates from kimberlite samples of the nearby Orapa and Letlhakane pipes (˜175 km west of the profile). The lithospheric mantle of the Ghanzi-Chobe belt is resistive, but its lithosphere is only about 180 km thick. At crustal depths a northward dipping boundary between the Ghanzi-Chobe and the Magondi belts is identified, and two middle to lower crustal conductors are discovered in the Magondi belt. The crustal terrane boundary between the Magondi and Ghanzi-Chobe belts is found to be located further to the north, and the southwestern boundary of the Zimbabwe craton might be further to the west, than previously inferred from the regional potential field data.

  11. Seismic Census Technique for African Elephants

    NASA Astrophysics Data System (ADS)

    Wood, J. D.; O'Connell-Rodwell, C. E.; Klemperer, S. L.

    2005-12-01

    Large mammal populations are difficult to census and monitor in remote areas. In particular, elephant populations in Central Africa are difficult to census due to dense forest making aerial surveys impractical. Conservation management would be improved by a census technique that was accurate and precise, did not require large efforts in the field, and could record numbers of animals over a period of time. We report a new detection technique that relies on sensing the footfalls of large mammals. Geophones were used to record the footfalls of elephants and other large mammal species at a water hole in Etosha National Park, Namibia. We were able to discriminate between species using the spectral content of their footfalls with an 85% accuracy rate while only using a single geophone. This was done using correlation coefficients comparing the shape of the spectra for various species. An ANOVA found significant differences between these correlation coefficients (F4,1785 = 147.78, P = 0.000). An estimate of the energy created by passing elephants (the area under the amplitude envelope) can be used to estimate the number of elephants passing the geophone. Our best regression line plotting number of elephants versus energy recorded in the geophone explained 55% of the variance in the data. Much of the unexplained variance is due to the variation in distance from the geophone to the passing elephants. By subjecting the recordings to a narrow band-pass filter and using beamforming techniques on array data, we believe that we can control for the variation in distance between animal and geophones, and thus achieve better estimates of the number of animals passing the array. Using 7 pairs of geophones in a linear array, we offset the pairs of time series to correspond with the time delay associated with the signal intersecting the pair of geophones at increments of 2 degrees. The offset time series were then summed and the RMS value calculated. The largest RMS value was then taken to indicate the most likely angle from which the signal intersected the pair of geophones. Lines were then plotted from the pairs of geophones at the angle with the highest RMS. The centroid of the line intersections was taken to be the location of the source signal. Thus far we have managed to localize the signal source within 15 meters of its true location.

  12. Lithospheric sutures, continental fragments and hot spots revealed by a transportable seismic array experiment in southeast Australia

    NASA Astrophysics Data System (ADS)

    Rawlinson, N.; Vanacore, E. A.; Pozgay, S.

    2011-12-01

    Beginning in 1998, passive seismic arrays have been progressively deployed throughout southeast Australia in an attempt to image the 3-D seismic structure of the underlying lithosphere at high resolution. To date, over 600 stations have been deployed as part of 14 separate arrays. Station spacing on the mainland is ˜50 km, which reduces to ˜20 km in Tasmania, an island that lies at the southern tip of the continent. The majority of stations use 3-component short period sensors (1 Hz natural frequency), but several of the early arrays use vertical component short period sensors, and a number of 3-component broadband sensors are distributed throughout. In the past, teleseismic traveltime tomography has been separately applied to data from most of the arrays. More recently, the emphasis has been on joint treatment of the data, with ambient noise tomography and teleseismic traveltime tomography being applied to multiple array data. The latest developments involve the use of an irregular grid approach for traveltime tomography which incorporates global ISC traveltimes as well as relative arrival times obtained from each array, thus enabling high resolution recovery of structure where justified by the path coverage. Differential attenuation tomography is also beginning to be applied, which complements the results obtained from the traveltime tomography. To date, a wealth of features have been revealed by 3-D seismic tomography, the most significant being: (1) an easterly dipping velocity transition zone which suggests that the older Delamerian Orogen extends beneath the younger Western Subprovince of the Lachlan Orogen; (2) a distinct region of low velocity in the upper mantle north of Melbourne, which can be associated with recent Quaternary hot-spot volcanism; (3) a gradual east-southeast decrease in velocity towards the coast, which is consistent with lithospheric stretching and thinning near a passive margin; (4) a zone of high velocity north of Adelaide that may

  13. Next-generation seismic experiments: wide-angle, multi-azimuth, three-dimensional, full-waveform inversion

    NASA Astrophysics Data System (ADS)

    Bell, Rebecca; Morgan, Joanna; Warner, Michael

    2016-04-01

    There are many outstanding plate-tectonic scale questions that require us to know information about sub-surface physical properties, for example ascertaining the geometry and location of magma chambers and estimating the effective stress along plate boundary faults. These important scientific targets are often too deep, impractical and expensive for extensive academic drilling. Full-waveform inversion (FWI) is an advanced seismic imaging technique that has recently become feasible in three dimensions, and has been widely adopted by the oil and gas industry to image reservoir-scale targets at shallow-to-moderate depths. In this presentation we explore the potential for 3-D FWI, when combined with appropriate marine seismic acquisition, to recover high-resolution high-fidelity P-wave velocity models for sub-sedimentary targets within the crystalline crust and uppermost mantle. Using existing geological and geophysical models, we construct P-wave velocity models over three potential sub-sedimentary targets: the Soufrière Hills Volcano on Montserrat and its associated crustal magmatic system, the downgoing oceanic plate beneath the Nankai subduction margin, and the oceanic crust-uppermost mantle beneath the East Pacific Rise mid-ocean ridge. We use these models to generate realistic multi-azimuth 3-D synthetic seismic data, and attempt to invert these data to recover the original models. We explore the resolution and accuracy, sensitivity to noise and acquisition geometry, ability to invert elastic data using acoustic inversion codes, and the trade-off between low frequencies and starting velocity model accuracy. We will show that FWI applied to multi-azimuth, refracted, wide-angle, low-frequency data can resolve features in the deep crust and uppermost mantle on scales that are significantly better than can be achieved by any other geophysical technique, and that these results can be obtained using relatively small numbers (60-90) of ocean-bottom receivers combined

  14. Nonstructural seismic restraint guidelines

    SciTech Connect

    Butler, D.M.; Czapinski, R.H.; Firneno, M.J.; Feemster, H.C.; Fornaciari, N.R.; Hillaire, R.G.; Kinzel, R.L.; Kirk, D.; McMahon, T.T.

    1993-08-01

    The Nonstructural Seismic Restraint Guidelines provide general information about how to secure or restrain items (such as material, equipment, furniture, and tools) in order to prevent injury and property, environmental, or programmatic damage during or following an earthquake. All SNL sites may experience earthquakes of magnitude 6.0 or higher on the Richter scale. Therefore, these guidelines are written for all SNL sites.

  15. The African-American History of Martha's Vineyard.

    ERIC Educational Resources Information Center

    Weintraub, Elaine

    1993-01-01

    Reports on research into African American history and experiences in Martha's Vineyard (Massachusetts). Examines primary sources and oral traditions of African American cultural and social history from 1703 to the present. Discusses African American sailors, race relations, and contributions by African American individuals to the community. (CFR)

  16. Juan de Fuca Plate Ridge-to-Trench Experiment: initial results from active source seismic imaging of the Juan de Fuca plate and Cascadia fore-arc (Invited)

    NASA Astrophysics Data System (ADS)

    Carbotte, S. M.; Canales, J.; Carton, H. D.; Han, S.; Gibson, J. C.; Janiszewski, H. A.; Horning, G.; Nedimovic, M. R.; Abers, G. A.; Trehu, A. M.

    2013-12-01

    Active source seismic data were acquired during the Juan de Fuca Ridge-to-Trench experiment (June-July 2012) to characterize the evolution and structure of the Juan de Fuca plate from formation at the ridge, through evolution in the plate interior, to subduction at the Cascadia trench. The survey provides plate-scale images of the sediments, crust, and shallowest mantle along two ridge-perpendicular transects, one extending from Axial seamount to the Oregon margin near Hydrate Ridge and the other from near Endeavour segment to Grays Harbor offshore Washington. In addition, a 450 km long trench-parallel line ~10 km seaward of the Cascadia deformation front was acquired to characterize variations in plate structure along the margin. Coincident long-streamer (8 km) multi-channel seismic (MCS) and wide-angle ocean bottom seismometer (OBS) data were collected along each transect. Using these data, our current investigations focus on the properties of the thick sediment blanket covering the Juan de Fuca plate and evidence for fluid flow at the deformation front, crustal structure within the plate interior and near the deformation front, and tracking the downgoing plate beneath the margin. Highlights include the discovery of numerous pockmarks on the seafloor providing evidence of active fluid flow up to 60 km west of the deformation front. Along the Oregon transect, a bright decollement horizon is imaged at ~1sec twtt above basement whereas at the Washington margin, protothrusts of the deformation front reach to the top of the oceanic crust. Variations in sediment properties are documented within the margin-parallel transect with changes in the stratigraphic level of decollement. While crustal thickness is quite uniform along the margin (~ 6 km), variations in crustal reflectivity and in shallowest mantle velocities are observed over ~30-50 km length scales that could be related to structural variations in the Cascadia subduction zone. Further landward, the top of the

  17. Topography and tectonics of the central New Madrid seismic zone: Results of numerical experiements using a three-dimensional boundary element program

    NASA Technical Reports Server (NTRS)

    Gomberg, Joan; Ellis, Michael

    1994-01-01

    We present results of a series of numerical experiments designed to test hypothetical mechanisms that derive deformation in the New Madrid seismic zone. Experiments are constrained by subtle topography and the distribution of seismicity in the region. We use a new boundary element algorithm that permits calcuation of the three-dimensional deformation field. Surface displacement fields are calculated for the New Madrid zone under both far-field (plate tectonics scale) and locally derived driving strains. Results demonstrate that surface displacement fields cannot distinguish between either a far-field simple or pure shear strain field or one that involves a deep shear zone beneath the upper crustal faults. Thus, neither geomorphic nor geodetic studies alone are expected to reveal the ultimate driving mechanism behind the present-day deformation. We have also tested hypotheses about strain accommodation within the New Madrid contractional step-over by including linking faults, two southwest dipping and one vertical, recently inferred from microearthquake data. Only those models with step-over faults are able to predict the observed topography. Surface displacement fields for long-term, relaxed deformation predict the distribution of uplift and subsidence in the contractional step-over remarkably well. Generation of these displacement fields appear to require slip on both the two northeast trending vertical faults and the two dipping faults in the step-over region, with very minor displacements occurring during the interseismic period when the northeast trending vertical faults are locked. These models suggest that the gently dippling central step-over fault is a reverse fault and that the steeper fault, extending to the southeast of the step-over, acts as a normal fault over the long term.

  18. "Come on Baby. You Know I Love You": African American Women's Experiences of Communication with Male Partners and Disclosure in the Context of Unwanted Sex.

    PubMed

    Gutzmer, Kyle; Ludwig-Barron, Natasha T; Wyatt, Gail E; Hamilton, Alison B; Stockman, Jamila K

    2016-05-01

    We examined African American women's experiences of communication with their male intimate partners a couple of hours before and after an incident of unwanted sex. We also examined women's experiences of disclosure following an incident of unwanted sex. Semi-structured qualitative interviews were conducted with a community-based sample of sexually active African American women (n = 19) reporting at least one incident of sexual coercion (i.e., being pressured into unwanted sex without consent) by an intimate male partner since the age of 18. Our analysis was guided by "the sexual division of power" from Connell's (1987) theory of gender and power. Data were analyzed inductively by examining the interviews for common themes in the following domains: communication before the unwanted sex, communication after the unwanted sex, and disclosure to others. Men pressured partners for unwanted sex through verbal and non-verbal tactics, ranging from pestering and blunt requests for sex to verbal bullying and violence. Many women responded by clearly saying no. However, many women also described eventually ceasing to resist their partners and engaging in unwanted sex. After the unwanted sex, men actively and passively avoided discussing the incident. Although many women discussed the unwanted sex with family and friends, less women disclosed to trained professionals. In some cases, women did not discuss the incident with anyone at all. These findings indicate that, when addressing sexual violence against women, there is a need to target men as well as the norms of masculinity that underpin physical and sexual violence against women. PMID:26892099

  19. Wide-angle seismic constraints on the nature and limits between geological domains in the Tyrrhenian basin (MEDOC-2010 experiment)

    NASA Astrophysics Data System (ADS)

    Sallares, V.; Prada, M.; Moeller, S.; Guzman, M.; Ranero, C. R.; Grevemeyer, I.; Zitellini, N.; de Franco, R.

    2012-12-01

    The Tyrrhenian Sea is a back-arc basin that opened between Neogene and present as a response to the roll-back of the subducted slab beneath the Apennines (to the West) and the Calabrian Arc (to the South). It underwent comparatively less extension in the North (offshore Corsica) than in the South, where it evolved until full continental breakup. The combination of geological observations (e.g. ODP drilling) and geophysical data (bathymetric, multichannel seismics) has provided a good background knowledge on the tectonic structure and geodynamic evolution of the basin, but the nature of the different geological domains and the limits between them remain poorly constrained. To partially overcome this issue, five wide-angle seismic (WAS) transects across the whole basin recorded by a dense array of OBH/S and landstations, were acquired in the framework of the MEDOC-2010 survey. The northernmost profile (AB) runs E-W from Southern Corsica to mainland Italy, whereas the southernmost one (MN) runs NW-SE from Southern Sardinia to Western Sicily. We present a compilation of seismic velocity models obtained by joint refraction and reflection travel-time inversion along these five profiles. The inverted models include maps of the P-wave velocity field together with the geometry of the crust-mantle boundary, providing clues on the nature of the rocks along the different transects, a key to define the parameters controlling extension. The continental crust beneath the coast in Corsica and Sardinia is similar in terms of thickness (23±2 km) and velocity. The crustal structure is clearly continental along the two northern profiles. Sediments mostly concentrate in small, isolated basins. An exception is the ~5 km-thick Corsica basin. A similar, but considerable narrower and less defined structure can also be observed offshore Sardinia. The minimum crustal thickness along profile AB is 18 km, so the corresponding stretching factor (β) is ~1.3; whereas along profile CD, it is 13

  20. Seismicity of southern Lake Tanganyika

    NASA Astrophysics Data System (ADS)

    Lavayssiere, A.; Gallacher, R. J.; Keir, D.; Ebinger, C. J.; Drooff, C.; Khalfan, M.; Bull, J. M.

    2015-12-01

    Global seismic networks document frequent and unusually deep earthquakes in East African rift sectors lacking central volcanoes. The deep seismicity means that we can use earthquakes to probe the geometry and kinematics of fault systems throughout the crust, and to understand the distribution of strain between large offset border fault systems and intrabasinal faults. The southern Tanganyika rift zone has the highest seismicity rate within East Africa during the period 1973-present, yet earlier temporary seismometer networks have been too sparse in space and time to relocate earthquakes with location and depth errors of < 5-10 km. We address this issue by recording seismicity of southern Lake Tanganyika since June 2014 using a network at 12 broadband seismic stations. The distribution of earthquakes shows that deformation primarily occurs on large offset border faults beneath the lake. Subsidiary earthquake activity occurs along the subparrallel Rukwa graben, and beneath the NE-SW striking Mweru rift. The distribution of earthquakes suggests the southern end of lake Tanganyika is characterized by a network of intersecting NNW and NE striking faults. The depths of earthquakes are distributed throughout the crust, consistent with the relatively strong lithosphere.