74,010 research outputs found
Seismic data reveal eastern Black Sea Basin structure
No full textRifted continental margins are formed by progressive extension of the lithosphere. The development of these margins plays an integral role in the plate tectonic cycle, and an understanding of the extensional process underpins much hydrocarbon exploration. A key issue is whether the lithosphere extends uniformly, or whether extension varies\ud
with depth. Crustal extension may be determined using seismic techniques. Lithospheric extension may be inferred from the waterloaded subsidence history, determined from\ud
the pattern of sedimentation during and after rifting. Unfortunately, however, many rifted margins are sediment-starved, so the subsidence history is poorly known.\ud
To test whether extension varies between the crust and the mantle, a major seismic experiment was conducted in February–March 2005 in the eastern Black Sea Basin (Figure 1), a deep basin where the subsidence history is recorded\ud
by a thick, post-rift sedimentary sequence. The seismic data from the experiment indicate the presence of a thick, low-velocity zone, possibly representing overpressured sediments. They also indicate that the basement and\ud
Moho in the center of the basin are both several kilometers shallower than previously inferred. These initial observations may have considerable impact on thermal models of the petroleum system in the basin. Understanding\ud
the thermal history of potential source rocks is key to reducing hydrocarbon exploration risk. The experiment, which involved collaboration between university groups in the United Kingdom, Ireland, and Turkey, and BP and\ud
Turkish Petroleum (TPAO), formed part of a larger project that also is using deep seismic reflection and other geophysical data held by the industry partners to determine the subsidence history and hence the strain evolution of\ud
the basin
K. M. Drew
No full textDrew sitting at a lab bench, reading a book placed next to a microscope.Inscriptions on image and/or album page: "#1600/K. M. Drew/'27"Digitized by: MBLWHOI Libraryimage/jpg black and white image reformatted digitalPhotograph
On the masses and evolutionary status of the black hole binary GX 339-4: a twin system of XTE J1550-564?
No full textWe apply the K-correction to the black hole low-mass X-ray binary (LMXB) GX 339-4 which implies MX? 6 M? by only assuming that the companion is more massive than ?0.17 M?, the lower limit allowed by applying a ‘stripped-giant’ model. This evolutionary model successfully reproduces the observed properties of the system. We obtain a maximum mass for the companion of M2? 1.1 M? and an upper limit to the mass ratio of q(=M2/MX) ? 0.125. The high X-ray activity displayed by the source suggests a relatively large mass transfer rate which, according to the model, results in M2? 0.3 M? and MX? 7 M?. We have also applied this scenario to the black hole binary XTE J1550-564, which has a similar orbital period but the donor is detected spectroscopically. The model successfully reproduces the observed stellar parameter
From Black Power to Black Studies How a Radical Social Movement Became an Academic Discipline
No full textShedding light on the black power movement, Black Studies programs, and American higher education, this historical analysis reveals how radical politics are assimilated into the university system.Intro -- Contents -- List of Figures and Tables -- Preface -- Acknowledgments -- Note on Terminology -- 1 The Movement That Became an Institution -- 2 The Road to Black Studies -- 3 Revolution at San Francisco State College -- 4 The Life and Death of Black Studies Programs -- 5 The Ford Foundation's Mission in Black Studies -- 6 Constructing the Discipline -- 7 Black Studies as the Loyal Opposition -- Appendixes -- A: Note on Research Method -- B: Archives Consulted -- C: Newspapers Consulted -- D: People Interviewed by the Author -- E: Sample Interview Questions -- F: Interviews Collected by Others -- G: Quantitative Data Used -- H: The Survey of Issues in Africana Studies -- Notes -- Index -- A -- B -- C -- D -- E -- F -- G -- H -- I -- J -- K -- L -- M -- N -- O -- P -- R -- S -- T -- U -- V -- W -- YShedding light on the black power movement, Black Studies programs, and American higher education, this historical analysis reveals how radical politics are assimilated into the university system.Description based on publisher supplied metadata and other sources.Electronic reproduction. Ann Arbor, Michigan : ProQuest Ebook Central, YYYY. Available via World Wide Web. Access may be limited to ProQuest Ebook Central affiliated libraries
Styx and Stones, and Other K/S Stories
No full textPhotocopy. Mar-87This publication may contain explicit sexual literary descriptions and/or artistic depictions
Black Hills State College football team, 1973
No full textCaption: "Jacket team members included: (Top row) M. Dutton, B. Fahey, S. Anderson, K. Williams, L. Hayes, S. Molzahn, D. Parker, L. Iverson; (second) G. Sharkey, D. Sabo, B. Krug, M. McRann, B. Handel, B. Geyer, R. Cox, B. Knapp, B. Blasy, P. Cody; (third) B. Parkyn, W. Johnson, B. Baloun, E. Sheridan, D. Broadie, R. Davis, L. Portwood, D. Mattern, J. Nieson, M. Ramey, T. Kelly; (fourth) D. Rossi, P. Dougherty, J. Perales, R. Farber, M. Miller, R. Meeker, R. Bean, R. Czmowski, M. Gabert; (bottom) M. Grossman, T. Wingerter, G. Dannenbring, D. Murphy, M. Berdahl, B. Fleak, D. Graslie, M. Kocmich, M. Bradeen, N. Anderson, T. Herman." Published in the Eociha, 1974, page 60
On the Inconsistency between the Black Hole Mass Function Inferred from M•-σ and M•-L Correlations
No full textBlack hole masses are tightly correlated with the stellar velocity dispersions of the bulges which surround them and slightly less well correlated with the bulge luminosity. It is common to use these correlations to estimate the expected abundance of massive black holes. This is usually done by starting from an observed distribution of velocity dispersions or luminosities and then changing variables. This procedure neglects the fact that there is intrinsic scatter in these black hole mass-observable correlations. Accounting for this scatter results in estimates of black hole abundances which are larger by almost an order of magnitude at masses >109 Msolar. Including this scatter is particularly important for models which seek to infer quasar lifetimes and duty cycles from the local black hole mass function. However, even when scatter has been accounted for, the M•-σ relation predicts fewer massive black holes than does the M•-L relation. This is because the σ-L relation in the black hole samples currently available is inconsistent with that in the SDSS sample from which the distributions of L or σ are based: the black hole samples have smaller L for a given σ, or larger σ for a given L. The σ-L relation in the black hole samples is similarly discrepant with that in other samples of nearby early-type galaxies. This suggests that current black hole samples are biased: if this is a selection rather than a physical effect, then the M•-σ and M•-L relations currently in the literature are also biased from their true values
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M• − σRelation For Intermediate-Mass Black Holes In Globular Clusters
No full textContext. For galaxies hosting supermassive black holes (SMBHs), it has been observed that the mass of the central black hole (M center dot) tightly correlates with the effective or central velocity dispersion (s) of the host galaxy. The origin of this M center dot - sigma scaling relation is assumed to lie in the merging history of the galaxies, but many open questions about its origin and the behavior in different mass ranges still need to be addressed. Aims. The goal of this work is to study the black-hole scaling relations for low black-hole masses, where the regime of intermediatemass black holes (IMBHs) in globular clusters (GCs) is entered. Methods. We collected all existing reports of dynamical black-hole measurements in GCs, providing black-hole masses or upper limits for 14 candidates. We plotted the black-hole masses versus different cluster parameters including total mass, velocity dispersion, concentration, and half-mass radius. We searched for trends and tested the correlations to quantify their significance using a set of different statistical approaches. For correlations with a high significance we performed a linear fit, accounting for uncertainties and upper limits. Results. We find a clear correlation between the mass of the IMBH and the velocity dispersion of the GC. As expected, the total mass of the GC then also correlates with the mass of the IMBH. While the slope of the M center dot - sigma correlation differs strongly from the one observed for SMBHs, the other scaling relations M center dot - M-tot, and M center dot - L are similar to the correlations in galaxies. Significant correlations of black-hole mass with other cluster properties were not found in the present sample.DFG cluster of excellence OriginStructure of the UniverseAustralian Research Council through Future Fellowship grant FT0991052Astronom
Braneworld black holes and black strings
No full textThis thesis involves the study of strong and weak gravity phenomenology within the braneworld paradigm. We begin with a general overview of the hypothesised concept of extra spatial dimensions and explain why they are so interesting. Turning next to the topic of classical four-dimensional black holes, we discuss their formation via gravitational collapse and indicate some of the strong observational evidence of their existence. We then merge the two independent theories of extra dimensions and black holes together to form braneworld black holes. Focusing our attention on two distinct braneworld scenarios, we examine the effects produced from either strong or weak gravity. The prospect of obtaining experimental verification of the existence of additional spacelike dimensions in the upcoming ground-based accelerators, makes the theoretical research of braneworld gravity within this thesis even more enticing. We start with a non-perturbative approach to look for exact, spherically symmetric star or black hole solutions on a Randall-Sundrum brane from the perspective of the five-dimensional spacetime. By fixing the background, we explore the permissible braneworld trajectories within it that correspond to a braneworld observer, the solutions of the brane Tolmann-Oppenheimer-Volkoff equations. A variety of static gravitating matter sources on the brane are obtained in a range of different backgrounds. Our final aim is a consistent brane embedding in a Schwarzschild- Anti de Sitter spacetime as these solutions are potential candidates for brane stars or black holes. The weak and dominant energy conditions determine the physically sensible solutions which have the interpretation of braneworld stars. We then study time-dependent trajectories as a possible description of time-dependent braneworld black holes. This work is then generalised by relaxing the simplifying assumption of Z(_2)-symmetry, previously imposed around the brane. Non-Z(_2) symmetric spacetimes are applicable in processes which concern only one side of the brane, for example black hole recoil or the emission of Hawking radiation. We determine that a subset of the allowed brane trajectories in an asymmetric background are exactly the same as the Z(_2)-symmetric case. Next, we explore perturbative gravity in the Hofava-Witten model of heterotic M-theory. The study of scalar and gravitational fluctuations determines that the radion mode is coupled to the bulk scalar field, indicating only one single degree of freedom. Our analysis also determines the instability of a black string. We then compute the complete mass spectrum of the graviton mode. Using the five-dimensional gravitational physics, we determine what the gravitational interaction an observer on the braneworld would perceive. This analysis involves the computation of the Newtonian potential between two test masses on the visible brane, together with the four-dimensional tensor structure of the massless graviton propagator. Finally, as an application to the earlier work, we comment on work which is in progress: the study of possible brane black hole solutions in low energy heterotic M-theory
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