Gender, Mentoring Experiences, and Salary Attainment among Graduates of an Historically Black University.

Science.gov (United States)

Dreher, George F.; Chargois, Josephine A.

1998-01-01

Survey responses from 170 of 685 African-American graduates of historically Black colleges revealed no gender-based pay differences. Those who had White male mentors had some pay advantages over those without mentors. (SK)

Historical Y. pestis Genomes Reveal the European Black Death as the Source of Ancient and Modern Plague Pandemics.

Science.gov (United States)

Spyrou, Maria A; Tukhbatova, Rezeda I; Feldman, Michal; Drath, Joanna; Kacki, Sacha; Beltrán de Heredia, Julia; Arnold, Susanne; Sitdikov, Airat G; Castex, Dominique; Wahl, Joachim; Gazimzyanov, Ilgizar R; Nurgaliev, Danis K; Herbig, Alexander; Bos, Kirsten I; Krause, Johannes

2016-06-08

Ancient DNA analysis has revealed an involvement of the bacterial pathogen Yersinia pestis in several historical pandemics, including the second plague pandemic (Europe, mid-14(th) century Black Death until the mid-18(th) century AD). Here we present reconstructed Y. pestis genomes from plague victims of the Black Death and two subsequent historical outbreaks spanning Europe and its vicinity, namely Barcelona, Spain (1300-1420 cal AD), Bolgar City, Russia (1362-1400 AD), and Ellwangen, Germany (1485-1627 cal AD). Our results provide support for (1) a single entry of Y. pestis in Europe during the Black Death, (2) a wave of plague that traveled toward Asia to later become the source population for contemporary worldwide epidemics, and (3) the presence of an historical European plague focus involved in post-Black Death outbreaks that is now likely extinct. Copyright © 2016 Elsevier Inc. All rights reserved.

Is It a Different World? Providing a Holistic Understanding of the Experiences and Perceptions of Non-Black Students at Historically Black Colleges and Universities

Science.gov (United States)

Arroyo, Andrew T.; Palmer, Robert T.; Maramba, Dina C.

2016-01-01

This qualitative study contributes an original holistic understanding of the perceptions and experiences of non-Black students (e.g., Asian American, Latino, and White) as they matriculate into historically Black colleges and universities (HBCUs), persist to graduation, and reflect on their experiences as graduates at HBCUs. Findings from this…

Old/Past/Ancient/Historic Frontiers in Black Hole Astrophysics

Science.gov (United States)

Trimble, Virginia

Basic questions about black holes, some of which are fairly old, include (1) What is a black hole? (2) Do black holes exist? And the answer to this depends a good deal on the answer to (1), (3) Where, when, why, and how have they formed? and (4) What are they good for? Here I attempt some elaboration of the questions and partial answers, noting that general relativity is required to described some of the phenomena, while dear old Isaac Newton is OK for others.

Low Graduation Rates among Historically Black Colleges and Universities (HBCU) Student Athletes

Science.gov (United States)

Parker, Alvin D.

2017-01-01

A review of literature reveals that there is a dearth of research examining the low graduation rates among student-athletes at historically Black colleges and universities (HBCU's). By comparison, there has been numerous studies that have examined the African American student-athlete attending predominately White institutions (PWI's). The…

The Historically Black College as Social Contract, Social Capital, and Social Equalizer.

Science.gov (United States)

Brown, M. Christopher, II; Davis, James Earl

2001-01-01

Historically black colleges and universities (HBCUs) enjoy a unique social contract in the national history, acting as social agencies for society by providing equal educational opportunity and attainment for all students. This social contract brokered between the nation and African Americans is realized through social capital or distribution and…

The Male Initiative on Leadership and Excellence (MILE) and Its Impact on Retention and Persistence of Black Men at Historically Black Colleges and Universities (HBCUs)

Science.gov (United States)

Palmer, Robert T.; Maramba, Dina C.; Dancy, T. Elon

2013-01-01

A strong body of research has documented the supportive environments of historically Black colleges and universities (HBCUs) and their impact on facilitating student success. Notwithstanding the consistency of these findings, recent reports and empirical research have highlighted the problems that HBCUs are experiencing with Black male enrollment,…

Stars Form Surprisingly Close to Milky Way's Black Hole

Science.gov (United States)

2005-10-01

The supermassive black hole at the center of the Milky Way has surprisingly helped spawn a new generation of stars, according to observations from NASA's Chandra X-ray Observatory. This novel mode of star formation may solve several mysteries about the supermassive black holes that reside at the centers of nearly all galaxies. "Massive black holes are usually known for violence and destruction," said Sergei Nayakshin of the University of Leicester, United Kingdom, and coauthor of a paper on this research in an upcoming issue of the Monthly Notices of the Royal Astronomical Society. "So it's remarkable that this black hole helped create new stars, not just destroy them." Black holes have earned their fearsome reputation because any material -- including stars -- that falls within the so-called event horizon is never seen again. However, these new results indicate that the immense disks of gas known to orbit many black holes at a "safe" distance from the event horizon can help nurture the formation of new stars. Animation of Stars Forming Around Black Hole Animation of Stars Forming Around Black Hole This conclusion came from new clues that could only be revealed in X-rays. Until the latest Chandra results, astronomers have disagreed about the origin of a mysterious group of massive stars discovered by infrared astronomers to be orbiting less than a light year from the Milky Way's central black hole, a.k.a. Sagittarius A*, or Sgr A*. At such close distances to Sgr A*, the standard model for star formation predicts that gas clouds from which stars form should have been ripped apart by tidal forces from the black hole. Two models to explain this puzzle have been proposed. In the disk model, the gravity of a dense disk of gas around Sgr A* offsets the tidal forces and allows stars to form; in the migration model, the stars formed in a star cluster far away from the black hole and migrated in to form the ring of massive stars. The migration scenario predicts about a

Business in Social Work Education: A Historically Black University's Social Work Entrepreneurship Project

Science.gov (United States)

Archibald, Paul; Muhammad, Omar; Estreet, Anthony

2016-01-01

The destabilization of the current economy has sparked increased interest in entrepreneurship, especially for underrepresented minority social work students. The entrepreneurial thinking of these social work students entering social work programs at historically Black colleges and universities needs to be fostered in a learning environment. This…

The transformation of everyday historical memory of the peasants of Central Black Earth region in the post-reform period

Directory of Open Access Journals (Sweden)

Andrei A. Linchenko

2016-09-01

Full Text Available The article deals with the metamorphosis of the everyday historical memory of the peasants of the Central Black Earth region. The common approach, linking the historical memory of the peasantry with historical knowledge about the kings, generals, historical figures exclusively is overcome on the basis of the constructive methodology for studying the historical memory. The transformation of daily historical memory of the post-reform peasants is described in the context of changing traditional notions of peasant about labor, life and leisure. The changes of traditional norms, values and objectives of economic, legal and family memory of the Russian peasantry are shown on the materials of different archival sources, the data of the Counties' statistics. It is shown that the traditional experience of the agricultural practices of the peasantry ceases to act as an important reference point of economic activity and forms another shape of economical memory that goes beyond land redistribution and traditional land inheritance. The conclusion is that the transformation of the public authorities of the peasantry in the post-reform period was associated with the overcoming of the traditional office, stereotipic behaviour of the officials. It has been shown that a significant enhancement of critical attitude to the traditions of the past is observed in the sphere of family relations.

The Relationship between Fundraising Practice and Job Satisfaction at Historically Black Colleges and Universities

Science.gov (United States)

Tindall, Natalie T. J.; Waters, Richard D.

2010-01-01

Fundraising, as studied from a communications/public relations perspective, is an understudied function. This research examines fundraising at public and private historically Black colleges and universities (HBCUs), specifically exploring how these fundraisers incorporate various fundraising strategies into their communication outreach programs…

Historically Black Colleges and Universities: Improving Operations through an Enterprise Resource Planning System

Science.gov (United States)

Hardee, Teresa

2012-01-01

There are a variety of challenges facing colleges and universities today. With shrinking public funding, many colleges and universities must rethink their operations to ensure that they are operating efficiently. Historically Black Colleges and Universities (HBCUs) have an even more daunting task in a downturned economy because they are often…

Black layers on historical architecture.

Science.gov (United States)

Toniolo, Lucia; Zerbi, Carlotta M; Bugini, Roberto

2009-03-01

The external surface of any building in urban polluted environment is unavoidably destined to be covered with layers that assume a grey to black colour and are generally called 'black crusts'. These, according to standard protocols and glossary, are deteriorated surface layers of stone material; they can have variable thickness, are hard and fragile and can detach spontaneously from the substrate, which, in general, is quite decayed. Plain visual examination may lead to consider 'black crusts' all similar, whilst only a careful diagnostic investigation can distinguish 'black crusts' and the consequences of their formation on stone substrates. In this paper, various black layers on marble are studied and compared and the morphological and compositional characteristics discussed according to the related mechanisms of formation. Differences between old (hundred years) and recent crusts (30 years) are investigated and pointed out. Samples of black crusts collected from the Milan Cathedral façade (Candoglia Marble) have been studied and compared with the careful and synergic employ of traditional techniques: optical (transmission and reflected VIS light) and electron microscopy, X-ray spectrometry and micro-Fourier transform infrared spectroscopy. Visual examination of loose fragments does not allow to point out outstanding differences amongst the various samples; black layers have similar main mineral components, gypsum and airborne particles, with different spatial distribution. The microscopic studies allowed to point out the porosity differences, the gypsum crystallisation habit, different amount of embedded particles, level and progress of marble decay. The observations lead to define three main types of black crusts: black crust deriving from marble sulphation, compact deposit and encrustation due to exogenic materials deposition. Black crusts show evidence of sulphation in progress, without a clear continuity solution between crust and marble; the lack of

75 FR 9747 - Promoting Excellence, Innovation, and Sustainability at Historically Black Colleges and Universities

Science.gov (United States)

2010-03-03

... Part V The President Executive Order 13532--Promoting Excellence, Innovation, and Sustainability..., Innovation, and Sustainability at Historically Black Colleges and Universities By the authority vested in me... the Secretary shall appoint a senior official to report directly to the department or agency head with...

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

Science.gov (United States)

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…

Understanding Richard Wright's "Black Boy": A Student Casebook to Issues, Sources, and Historical Documents.

Science.gov (United States)

Felgar, Robert

In "Black Boy," Richard Wright triumphs over an ugly, racist world by fashioning an inspiring, powerful, beautiful, and fictionalized autobiography. To help students understand and appreciate his story in the cultural, political, racial, social, and literary contexts of its time, this casebook provides primary historical documents,…

EVIDENCE FOR THREE ACCRETING BLACK HOLES IN A GALAXY AT z ∼ 1.35: A SNAPSHOT OF RECENTLY FORMED BLACK HOLE SEEDS?

International Nuclear Information System (INIS)

Schawinski, Kevin; Urry, Meg; Treister, Ezequiel; Simmons, Brooke; Natarajan, Priyamvada; Glikman, Eilat

2011-01-01

One of the key open questions in cosmology today pertains to understanding when, where, and how supermassive black holes form. While it is clear that mergers likely play a significant role in the growth cycles of black holes, the issue of how supermassive black holes form, and how galaxies grow around them, still needs to be addressed. Here, we present Hubble Space Telescope Wide Field Camera 3/IR grism observations of a clumpy galaxy at z = 1.35, with evidence for 10 6 -10 7 M ☉ rapidly growing black holes in separate sub-components of the host galaxy. These black holes could have been brought into close proximity as a consequence of a rare multiple galaxy merger or they could have formed in situ. Such holes would eventually merge into a central black hole as the stellar clumps/components presumably coalesce to form a galaxy bulge. If we are witnessing the in situ formation of multiple black holes, their properties can inform seed formation models and raise the possibility that massive black holes can continue to emerge in star-forming galaxies as late as z = 1.35 (4.8 Gyr after the big bang).

Racial Microaggressions among Asian American and Latino/a Students at a Historically Black University

Science.gov (United States)

Palmer, Robert T.; Maramba, Dina C.

2015-01-01

Research illustrates that the enrollments of Asian American and Latino/a students are increasing at historically Black colleges and universities (HBCUs). Nevertheless, research on how these students experience the institutional climates of HBCUs is nonexistent; hence, we sought to explore the college-choice process and perceptions of campus…

Historical record of black carbon in urban soils and its environmental implications

International Nuclear Information System (INIS)

He Yue; Zhang Ganlin

2009-01-01

Energy use in urbanization has fundamentally changed the pattern and fluxes of carbon cycling, which has global and local environmental impacts. Here we have investigated organic carbon (OC) and black carbon (BC) in six soil profiles from two contrast zones in an ancient city (Nanjing) in China. BC in soils was widely variable, from 0.22 to 32.19 g kg -1 . Its average concentration in an ancient residential area (Zone 1) was, 0.91 g kg -1 , whereas in Zone 2, an industrial and commercial area, the figure was 8.62 g kg -1 . The ratio of BC/OC ranged from 0.06 to 1.29 in soil profiles, with an average of 0.29. The vertical distribution of BC in soil is suggested to reflect the history of BC formation from burning of biomass and/or fossil fuel. BC in the surface layer of soils was mainly from traffic emission (especially from diesel vehicles). In contrast, in cultural layers BC was formed from historical coal use. The contents of BC and the ratio of BC/OC may reflect different human activities and pollution sources in the contrasting urban zones. In addition, the significant correlation of heavy metals (Cu, Pb, and Zn) with BC contents in some culture layers suggests the sorption of the metals by BC or their coexistence resulted from the coal-involved smelting. - Soil black carbon can reflect the pollution history of a city during urbanization.

Adaptation of warrant price with Black Scholes model and historical volatility

Science.gov (United States)

Aziz, Khairu Azlan Abd; Idris, Mohd Fazril Izhar Mohd; Saian, Rizauddin; Daud, Wan Suhana Wan

2015-05-01

This project discusses about pricing warrant in Malaysia. The Black Scholes model with non-dividend approach and linear interpolation technique was applied in pricing the call warrant. Three call warrants that are listed in Bursa Malaysia were selected randomly from UiTM's datastream. The finding claims that the volatility for each call warrants are different to each other. We have used the historical volatility which will describes the price movement by which an underlying share is expected to fluctuate within a period. The Black Scholes model price that was obtained by the model will be compared with the actual market price. Mispricing the call warrants will contribute to under or over valuation price. Other variables like interest rate, time to maturity date, exercise price and underlying stock price are involves in pricing call warrants as well as measuring the moneyness of call warrants.

NCLEX-RN Examination Performance by BSN Graduates of Four Historically Black Colleges and Universities

Science.gov (United States)

Chesney, Anita M.

2010-01-01

This qualitative multiple-case study research explored and described differences as well as NCLEX-RN preparation strategies used by Historically Black College and University (HBCU) baccalaureate nursing programs with consistent NCLEX pass rates versus those with inconsistent pass rates. Two of the four selected programs had a history of consistent…

The Crisis in Black and Black.

Science.gov (United States)

Hutchinson, Earl Ofari

These essays explore why the historic conflict between blacks and whites in the United States has become a crisis that divides many African Americans. The changing racial dynamic is not marked by conflicts. between the black middle class and the poor, black men and women, the black intellectual elite and rappers, black politicians and the urban…

Cultural Diversity in Introductory Psychology Textbook Selection: The Case for Historically Black Colleges/Universities (HBCUs)

Science.gov (United States)

Whaley, Arthur L.; Clay, William A. L.; Broussard, Dominique

2017-01-01

The present study describes a culturally relevant approach to introductory psychology textbook selection for students attending a historically Black college/university (HBCU). The following multistage procedure was used: (1) a survey of HBCU psychology departments was conducted to ascertain how they selected their introductory psychology…

Scholarly Productivity of Social Work Faculty at Historically Black Colleges and Universities: Are h-Index Scores a Suitable Measure?

Science.gov (United States)

Marshall, Isiah, Jr.; Smith, Belinda Davis; Green, Makeba T.; Anderson, Brian; Harry, Sonja V.; Byrd, Yolanda M.; Pratt-Harris, Natasha C.; Bolden, Errol S.; Hill, Solomon

2016-01-01

Faculty scholarship at historically Black colleges and universities (HBCU) has in the past served as a blueprint for the Black masses. Even today, HBCU faculty scholarship continues to be an informative source to communicate accurate information regarding marginalized groups. This study examines h-index scores of 65 faculty members at five…

A Historical Review of High Speed Metal Forming

OpenAIRE

Zittel, G.

2010-01-01

This paper will present a Historical Review of High Speed Metal Forming beginning with the first thought of forming metal by using an electromagnetic impulse to today, whereby High Speed Metal Forming is an accepted production process. Although this paper will briefly cover the basic physics of the process, it will not dwell on it. It will rather show how the industrial acceptance of High Speed Metal Forming is tightly connected to the knowledge acquired from many applications studies. These ...

Fewer Resources, More Debt: Loan Debt Burdens Students at Historically Black Colleges and Universities

Science.gov (United States)

Saunders, Katherine M.; Williams, Krystal L.; Smith, Cheryl L.

2016-01-01

Student loans have become an increasingly important way for students and their families to pay for college, but for students at historically black colleges and universities (HBCUs), student loan debt is a substantial burden. Students who attend these institutions--many of whom are low-income and first-generation--must borrow at higher rates and,…

Exploring the Impact of Historically Black Colleges in Promoting the Development of Undergraduates' Self-Concept.

Science.gov (United States)

Berger, Joseph B.; Milem, Jeffrey F.

2000-01-01

Study explores how institutional context affects the development of self-concept in a sample of 273 African American college students. Findings suggest that students attending church affiliated historically Black colleges develop significantly higher self-ratings in three domains of self-concept-psychosocial wellness, academic, and achievement…

Exploring Perspectives of Transitional Leadership Styles at Historically Black Colleges and Universities: A Case Study

Science.gov (United States)

Mosley, Melvin L.

2017-01-01

Historically Black Colleges and Universities (HBCUs) continue to strive for academic relevance in spite of the national problem of the misalignment of mission and values among their institutional leadership. The national problem was important to both the HBCU institutions and the entire academic community to establish global relevancy. The…

3 CFR 8404 - Proclamation 8404 of August 30, 2009. National Historically Black Colleges and Universities Week...

Science.gov (United States)

2010-01-01

..., to the growth of local communities, and to our Nation's overall economy. This week, we celebrate the... new, innovative, and ambitious strategies to help the next generation of Americans successfully complete college and prepare themselves for the global economy. During National Historically Black Colleges...

20 CFR 422.512 - Applications and related forms used in the black lung benefits program.

Science.gov (United States)

2010-04-01

... black lung benefits program. 422.512 Section 422.512 Employees' Benefits SOCIAL SECURITY ADMINISTRATION... black lung benefits program. (a) Application forms. The following forms are prescribed for use in... Act of 1969, as amended by the Black Lung Benefits Act of 1972: SSA-46—Application for Benefits Under...

32 CFR 22.325 - Historically Black colleges and universities (HBCUs) and other minority institutions (MIs).

Science.gov (United States)

2010-07-01

... 32 National Defense 1 2010-07-01 2010-07-01 false Historically Black colleges and universities (HBCUs) and other minority institutions (MIs). 22.325 Section 22.325 National Defense Department of Defense OFFICE OF THE SECRETARY OF DEFENSE DoD GRANT AND AGREEMENT REGULATIONS DoD GRANTS AND AGREEMENTS-AWARD AND ADMINISTRATION Competition § 22.325...

Making Bricks without Straw: The Kresge HBCU Initiative and Fundraising at Historically Black Colleges and Universities

Science.gov (United States)

Leak, Halima N.

2018-01-01

Historically Black Colleges and Universities (HBCUs) have a history of "doing more with less" and this is often reflected in their effectiveness in securing financial resources from private donors. The purpose of this study is to probe and explore how the Kresge Foundation's HBCU Initiative strengthened HBCU fundraising capacity from…

GC/MS in the study of deterioration process of historical monuments: characterization of the black crust formed in the Cathedral of Seville; GC/MS en el estudio del proceso de deterioro de monumentos historicos: caracterizacion de la costra negra presente en la Catedral de Sevilla

Energy Technology Data Exchange (ETDEWEB)

Reyes, J. [Programa de Corrosion del Golfo de Mexico. Universidad Autonoma de Campeche. Av. Agustin Melgar s/n, Campeche (Mexico); Hermosin, B.; Saiz J, C. [Instituto de Recursos Naturales y Agrobiologia de Sevilla. Avenida de la Reina Mercedes 10. Sevilla, Espana (Spain)]. e-mail: javreyes@uacam.mx

2006-07-01

Here, we present an interesting application of Gas Chromatography/Mass Spectrometry (GC/MS) technique which permitted to differentiate successfully between natural and anthropogenic compounds present in the black crust formed in the Cathedral of Seville. This building, considered as one of the most important historic and cultural European monuments suffers from intense blackening of its outside walls and sculptures due to the interaction with the urban environment. Fragment of black crusts were removed from the Cathedral walls and extraction process with organic solvents was carried out. The aliphatic, aromatic and polar fractions were separated and analyzed using GC/MS. A complex organic composition of the black crusts indicated the accumulative character of the deposition process of atmospheric particles as a function of the time. The presence of high molecular weight n-alkanes, n-fatty acids and natural molecular markers identified during the study were indicative of current biogenic contributions. It was also found an important group of petrogenic molecular markers related with diesel soot emissions from motor engines. The diesel soot and molecular markers were entrapped within the black crust mineral matrix and contribute to the observed blackening of the Seville Cathedral. (Author)

Constraints on cosmic strings due to black holes formed from collapsed cosmic string loops

International Nuclear Information System (INIS)

Caldwell, R.R.; Gates, E.

1993-05-01

The cosmological features of primordial black holes formed from collapsed cosmic string loops are studied. Observational restrictions on a population of primordial black holes are used to restrict f, the fraction of cosmic string loops which collapse to form black holes, and μ, the cosmic string mass-per-unit-length. Using a realistic model of cosmic strings, we find the strongest restriction on the parameters f and μ is due to the energy density in 100MeV photons radiated by the black holes. We also find that inert black hole remnants cannot serve as the dark matter. If earlier, crude estimates of f are reliable, our results severely restrict μ, and therefore limit the viability of the cosmic string large-scale structure scenario

Not yet human: implicit knowledge, historical dehumanization, and contemporary consequences.

Science.gov (United States)

Goff, Phillip Atiba; Eberhardt, Jennifer L; Williams, Melissa J; Jackson, Matthew Christian

2008-02-01

Historical representations explicitly depicting Blacks as apelike have largely disappeared in the United States, yet a mental association between Blacks and apes remains. Here, the authors demonstrate that U.S. citizens implicitly associate Blacks and apes. In a series of laboratory studies, the authors reveal how this association influences study participants' basic cognitive processes and significantly alters their judgments in criminal justice contexts. Specifically, this Black-ape association alters visual perception and attention, and it increases endorsement of violence against Black suspects. In an archival study of actual criminal cases, the authors show that news articles written about Blacks who are convicted of capital crimes are more likely to contain ape-relevant language than news articles written about White convicts. Moreover, those who are implicitly portrayed as more apelike in these articles are more likely to be executed by the state than those who are not. The authors argue that examining the subtle persistence of specific historical representations such as these may not only enhance contemporary research on dehumanization, stereotyping, and implicit processes but also highlight common forms of discrimination that previously have gone unrecognized. (c) 2008 APA, all rights reserved

Unfinished Business: The Uneven Past and Uncertain Future of One Historically Black University's Archives--A Personal Reflection

Science.gov (United States)

Pevar, Susan Gunn

2011-01-01

This article presents a perspective on how the restructuring of a historically black university's library and resulting closure of its special collections and archives puts important records pertaining to African American history in jeopardy. This article traces the recent history of special collections and archives at the Lincoln University…

Colorism within the Historically Black Colleges and Universities (HBCUs)

Science.gov (United States)

Gasman, Marybeth; Abiola, Ufuoma

2016-01-01

Complexion privilege and color bias have long acted in concert with racism to foster intraracial forms of stratification among African Americans such as the tendency for educational levels and other measureable outcomes (e.g., income) to correspond with skin tone. In this article, we examine the salience of color prejudice at Historically Black…

Postbaccalaureate Salaries of Psychology Majors from a Historically Black University: How Much Does a Master's Degree Add?

Science.gov (United States)

Sibulkin, Amy E.; Butler, J. S.

2016-01-01

A sample of predominantly African American psychology major baccalaureates from a historically Black university self-reported job types, salaries, and master's degree completion. For this pre-2009 recession sample, we found that (a) the rates of employment were quite high; (b) most jobs were related to health, mental health, social work, and…

Dynamics of a Successful Planned Giving Program Utilizing Shared Leadership at Historically Black Colleges and Universities (HBCUs)

Science.gov (United States)

Baldwin, Robin Lynn Brunty

2013-01-01

The purpose of this study was to evaluate the dynamics of a successful planned giving program utilizing shared leadership at Historically Black Colleges and Universities (HBCUs). This information will assist the leadership in determining if and how a successful planned giving program can be established for HBCUs. It is possible for planned gifts…

Can static regular black holes form from gravitational collapse?

International Nuclear Information System (INIS)

Zhang, Yiyang; Zhu, Yiwei; Modesto, Leonardo; Bambi, Cosimo

2015-01-01

Starting from the Oppenheimer-Snyder model, we know how in classical general relativity the gravitational collapse of matter forms a black hole with a central spacetime singularity. It is widely believed that the singularity must be removed by quantum-gravity effects. Some static quantum-inspired singularity-free black hole solutions have been proposed in the literature, but when one considers simple examples of gravitational collapse the classical singularity is replaced by a bounce, after which the collapsing matter expands for ever. We may expect three possible explanations: (i) the static regular black hole solutions are not physical, in the sense that they cannot be realized in Nature, (ii) the final product of the collapse is not unique, but it depends on the initial conditions, or (iii) boundary effects play an important role and our simple models miss important physics. In the latter case, after proper adjustment, the bouncing solution would approach the static one. We argue that the ''correct answer'' may be related to the appearance of a ghost state in de Sitter spacetimes with super Planckian mass. Our black holes have indeed a de Sitter core and the ghost would make these configurations unstable. Therefore we believe that these black hole static solutions represent the transient phase of a gravitational collapse but never survive as asymptotic states. (orig.)

“Nothing Better or Worse than Being Black, Gay, and in the Band”: A Qualitative Examination of Gay Undergraduates Participating in Historically Black College or University Marching Bands

Science.gov (United States)

Carter, Bruce Allen

2013-01-01

This collective case study examined the experiences of four African American gay band students attending historically Black colleges or universities (HCBUs) in the southern United States. This study explored influences that shaped the participants' identities as they negotiated numerous complex sociocultural discourses pervasive and challenging to…

Historically Black Colleges and Universities Radioactive Waste Management Research Program: Summary of activities, 1985-1986

International Nuclear Information System (INIS)

1986-01-01

This report summarizes the 1985 to 1986 activities of the Historically Black Colleges and Universities (HBCUs) Radioactive Waste Management Research Program sponsored by the Office of Civilian Radioactive Waste Management of the US Department of Energy (DOE). The first set of three awards was made in September,1984. In September, 1985, two of these projects were renewed and a new proposal was funded. The program has been enthusiastically received by the community of HBCUs and the program sponsor

Performance Pay Preferences of College of Education Faculty and Administrators at One Historically Black University: A Case Study

Science.gov (United States)

Jones, Corey Lee

2012-01-01

The purpose of this study was to determine the attitudes and perceptions College of Education faculty and administrators have about performance pay at a Historically Black University (HBCU). A secondary purpose of the study was to determine the performance pay plan and specific measures of faculty productivity preferred by College of Education…

Racial and Athletic Identity of African American Football Players at Historically Black Colleges and Universities and Predominantly White Institutions

Science.gov (United States)

Steinfeldt, Jesse A.; Reed, Courtney; Steinfeldt, M. Clint

2010-01-01

This study examined racial and athletic identity among African American football players at historically Black colleges and universities (HBCUs) and predominantly White institutions (PWIs). Negotiating the dualism of racial and athletic identities can be problematic because both roles are subject to prejudice and discrimination, particularly for…

Self-Esteem, Locus of Control, and First-Time NCLEX-RN Passage of BSN Students at Historically Black Colleges and Universities.

Science.gov (United States)

Chavis, Pamella Ivey

Relationships between self-esteem, locus of control (LOC), and first-time passage of National Council Licensure Examination for Registered Nurses (NCLEX-RN®) were examined at baccalaureate nursing programs at two historically black colleges and universities. Shortages continue to exceed demands for RNs prepared at the baccalaureate level. Inconsistent pass rates on the NCLEX-RN for graduates of historically black colleges and universities impede the supply of RNs. Surveys and archival data were used to examine characteristics of the sample and explore relationships among variables. All participants (N = 90) reported high self-esteem and internal LOC. Models suggested that all those with high self-esteem and internal LOC would pass the NCLEX-RN; only 85 percent passed the first time. Statistical analysis revealed a lack of statistical significance between self-esteem, LOC, and first-time passage. Variables not included in the study may have affected first-time passage.

A Delineation of Asian American and Latino/a Students' Experiences with Faculty at a Historically Black College and University

Science.gov (United States)

Palmer, Robert T.; Maramba, Dina C.

2015-01-01

Research has shown that the enrollment of Asian American and Latino/a students are increasing at historically Black colleges and universities (HBCUs). Nevertheless, research on how these students experience the institutional climate of HBCUs is nonexistent. Hence, this study sought to explore the college choice process and perceptions of campus…

Chandra Sees Wealth Of Black Holes In Star-Forming Galaxies

Science.gov (United States)

2001-06-01

NASA's Chandra X-ray Observatory has found new populations of suspected mid-mass black holes in several starburst galaxies, where stars form and explode at an unusually high rate. Although a few of these objects had been found previously, this is the first time they have been detected in such large numbers and could help explain their relationship to star formation and the production of even more massive black holes. At the 198th meeting of the American Astronomical Society in Pasadena, California, three independent teams of scientists reported finding dozens of X-ray sources in galaxies aglow with star formation. These X-ray objects appear point-like and are ten to a thousand times more luminous in X-rays than similar sources found in our Milky Way and the M81 galaxy. "Chandra gives us the ability to study the populations of individual bright X-ray sources in nearby galaxies in extraordinary detail," said Andreas Zezas, lead author from the Harvard-Smithsonian Center for Astrophysics team that observed The Antennae, a pair of colliding galaxies, and M82, a well-known starburst galaxy. "This allows us to build on earlier detections of these objects and better understand their relationship to starburst galaxies." Antennae-True Color Image True Color Image of Antennae Credit: NASA/SAO/G.Fabbiano et al. Press Image and Caption Kimberly Weaver, of NASA's Goddard Space Flight Center in Greenbelt, MD, lead scientist of the team that studied the starburst galaxy NGC 253, discussed the importance of the unusual concentration of these very luminous X-ray sources near the center of that galaxy. Four sources, which are tens to thousands of times more massive than the Sun, are located within 3,000 light years of the galaxy core. "This may imply that these black holes are gravitating toward the center of the galaxy where they could coalesce to form a single supermassive black hole," Weaver suggested. "It could be that this starburst galaxy is transforming itself into a quasar

Reimagining the Historically Black College and University (HBCU) Environment: Exposing Race Secrets and the Binding Chains of Respectability and Othermothering

Science.gov (United States)

Njoku, Nadrea; Butler, Malika; Beatty, Cameron C.

2017-01-01

This article investigates how the intersections of gender, race, policy, and student differences at historically Black colleges and universities (HBCUs) can impact student experience. Such an environment can displace and penalize those who do not adhere to the uniformity of heteronormative gender roles or respectability politics. Using…

Substance use problems reported by historically Black college students: combined marijuana and alcohol use versus alcohol alone.

Science.gov (United States)

Rhodes, Warren A; Peters, Ronald J; Perrino, Carrol S; Bryant, Sharronne

2008-06-01

Using secondary data analysis,this study compares alcohol and other drug (AOD) problems experienced by African-American students attending a historically Black university who use alcohol only versus those who use alcohol plus marijuana. Results indicate that students who used marijuana plus alcohol experienced more AOD problems than their counterparts who used alcohol only. The current findings are similar to previous research with a majority White college student population.

Institutional Retention Strategies at Historically Black Colleges and Universities and Their Effects on Cohort Default Rates: 1987-1995. Monograph Series.

Science.gov (United States)

Galloway, Fred J.; Swail, Watson Scott

This study analyzed institutional factors that significantly affect cohort default rates at historically black colleges and universities (HBCUs) and assessed the potential for reducing these rates. It has been hypothesized that the HBCUs most successful in lowering student cohort default rates are those that have also succeeded in increasing…

An Analysis of Stereotype Threat in African American Engineering Students at Predominantly White, Ethnically Diverse, and Historically Black Colleges and Universities

Science.gov (United States)

Sparks, David M.

2013-01-01

The purpose of this research was to distinguish the similarities and differences in coping strategies of African American engineering students by analyzing their perceptions of stereotype threat at three academic institution types, Predominantly White Institutions (PWI), ethnically diverse, and Historically Black Colleges and Universities (HBCUs).…

Systematic study of terahertz time-domain spectra of historically informed black inks.

Science.gov (United States)

Bardon, Tiphaine; May, Robert K; Taday, Philip F; Strlič, Matija

2013-09-07

The potential of terahertz-time domain spectroscopy (THz-TDS) as a diagnostic tool for studies of inks in historical documents is investigated in this paper. Transmission mode THz-TDS was performed on historically informed model writing and drawing inks. Carbon black, bistre and sepia inks show featureless spectra between 5 and 75 cm(-1) (0.15-2.25 THz); however, their analysis still provided useful information on the interaction of terahertz radiation with amorphous materials. On the other hand, THz-TDS can be used to distinguish different iron gall inks with respect to the amount of iron(II) sulfate contained, as sharp spectral features are observed for inks containing different ratios of iron(II) sulfate to tannic or gallic acid. Additionally, copper sulfate was found to modify the structure of iron(II) precipitate. Furthermore, Principal Component Analysis (PCA) applied to THz-TDS spectra, highlights changes in iron gall inks during thermal degradation, during which a decrease in the sharp spectral bands associated with iron(II) sulfate is observed. ATR-FTIR spectroscopy combined with THz-TDS of dynamically heated ink samples indicate that this phenomenon is due to dehydration of iron(II) sulfate heptahydrate. While this research demonstrates the potential of THz-TDS to improve monitoring of the chemical state of historical documents, the outcomes go beyond the heritage field, as it also helps to develop the theoretical knowledge on interactions between terahertz radiation and matter, particularly in studies of long-range symmetry (polymorphism) in complex molecular structures and the role played by the surrounding matrix, and also indicates the potential of THz-TDS for the optimization of contrast in terahertz imaging.

100y DASCH Search for historical outbursts of Black Hole Low Mass X-ray Binaries

Science.gov (United States)

Grindlay, Jonathan E.; Miller, George; Gomez, Sebastian

2018-01-01

Black Hole Low mass X-ray binaries (BH-LMXBs) are all transients, although several (e.g. GRS1915+109 and GX339-4) are quasi-persistent. All of the now 22 dynamically confirmed BH-LMXBs were discovered by their luminous outbursts, reaching Lx ~10^37 ergs/s, with outburst durations of typically ~1-3 months. These systems then (with few exceptions) return to a deep quiescent state, with Lx reduced by factors ~10^5-6 and hard X-ray spectra. The X-ray outbursts are accompanied by optical outbursts (if not absorbed by Galactic extinction) with ~6-9 magnitude increases and similar lightcurve shapes and durations as the X-ray (discovery) outburst. Prior to this work, only 3 BH-LMXBs have had historical (before the X-ray discovery) outbursts found in the archival data: A0620-00, the first BH-LMXB to be so identified, V404 Cyg (discoverd as "Nova Cyg" in 1938 and regarded as a classical nova), and V4641-Sgr which was given its variable star name when first noted in 1975. We report on the historical outbursts now discovered from the DASCH (Digital Access to a Sky Century @ Harvard) data from scanning and digitizing the now ~210,000 glass plates in the northern Galactic Hemisphere. This was one of the primary motivations for the DASCH project: to use the detection (or lack threof) of historic outbursts to measure or constrain the Duty Cycle of the accreting black holes in these systems. This, in turn, allows the total population of BH-LMXBs to be estimated and compared with that for the very similar systems containing neutron stars as the accretor (NS-LMXBs). Whereas the ratio of BHs/NSs from stellar evolution and IMFs is expected to be <<1, the DASCH results on half the sky point to an excess of BH-LMXBs. This must constrain the formation process for these systems, of importance for understanding both BH formation and compact binary evolution.

Owning the Journey: Using Collaborative Revisions of Little Red Riding Hood in Teaching Introduction to Literature at a Historically Black University

Science.gov (United States)

Scott, Pauline

2012-01-01

Design and implementation of a collaborative course project, using Little Red Riding Hood (LRRH) to teach and discuss the concepts of orality, cultural legacy, archetypes, adaptation/appropriation, and social criticism in an Introduction to Literature course at Historically Black Alabama State University in Montgomery, Alabama. The student groups…

Alumni Giving: A Case Study of the Factors That Influence Philanthropic Behavior of Alumni Donors of Historically Black Colleges and Universities

Science.gov (United States)

Roy-Rasheed, Lupita D.

2012-01-01

This research project was a study of the philanthropic behavior of local alumni donors at two historically Black colleges and universities (HBCUs) in the South Central Region. Specifically, the research explored HBCUs' local alumni donors' experiences, perceptions, triggers, and motivations and how these factors influence alumni giving. This…

MARTIN HEIDEGGER’S BLACK NOTEBOOKS AND POLITICAL ECONOMY OF CONTEMPORARY PHILOSOPHICAL CRITIQUE

Directory of Open Access Journals (Sweden)

A. O. Karpenko

2016-06-01

Full Text Available The purpose of the study is to determine the key strategies of philosophical criticism of Heidegger’s Black Notebooks, whose achievement is realized in the following tasks: 1 to identify the body of texts that represent the discourse of philosophical criticism of Heidegger notes; 2 to reveal the typological features of the different strategies of interpreting Black Notebooks; 3 to reconstruct a thematic horizon of Heidegger studies, opened up by discussion on published notes. The methodology combines elements of discourse analysis with traditional methods of historical and philosophical criticism. Scientific novelty is expressed in the following: 1 philosophical discourse of the Notebooks’ reception includes texts of narrowly specialized character (Gatherings collection of articles, as well as reflections of key philosophers (A. Badiou, J.-L. Nancy 2 basic strategies in philosophical critique of Black Notebooks convey the overall structure of the discourse of interpretation of Heidegger’s legacy, distributed between apologetics and ideological criticism; 3 Black Notebooks have exacerbated the problem of architectonics of Gesammtausgabe and formed the textual basis for the study of "silence" period in philosophical life of Heidegger. Conclusions. The discourse of philosophical critique of Heidegger’s notes proves evidence for ideological charge of philosophizing and justifies socially oriented approaches of historical and philosophical studies examining philosophizing as a special cultural practice, not as a form of sublime creativity.

Journalism and Mass Communication Students at Historically Black Colleges and Universities and Predominantly White Institutions: Saying Goodbye to the Digital Divide

Science.gov (United States)

Crawford, Jerry, II

2013-01-01

The digital divide has been described as the distance or gap in access to information based on race, ethnicity, income, education and geographical location. This study examined how freshmen and first-semester journalism and mass communications students at five Historically Black Colleges and Universities [HBCUs] have been able to bridge the…

Second-Class, Cash Strapped, Antiquated Institutions: Unbalanced Media Depictions of Historically Black Colleges and Universities in the "Chronicle of Higher Education"

Science.gov (United States)

Waymer, Damion; Street, Joshua

2016-01-01

Purpose: The purpose of this paper is to examine "The Chronicle of Higher Education", a leading site for higher education news and politics, and its representation of historically black colleges and universities (HBCUs). Design/methodology/approach: Frames are strong discursive tools that can help social actors achieve the following:…

Forms of presentism in the history of science. Rethinking the project of historical epistemology.

Science.gov (United States)

Loison, Laurent

2016-12-01

Since the late 1980s, presentism has seen a resurgence among some historians of science. Most of them draw a line between a good form of presentism and typical anachronism, but where the line should be drawn remains an open question. The present article aims at resolving this problem. In the first part I define the four main distinct forms of presentism at work in the history of science and the different purposes they serve. Based on this typology, the second part reconsiders what counts as anachronism, Whiggism and positivist history. This clarification is used as a basis to rethink the research program of historical epistemology in the third section. Throughout this article, I examine the conceptual core of historical epistemology more than its actual history, from Bachelard to Foucault or others. Its project should be defined - as Canguilhem suggested - as an attempt to account for both the contingency and the rationality of science. As such, historical epistemology is based on a complex fifth form of presentism, which I call critical presentism. The critical relation at stake not only works from the present to the past, because of the acknowledged rationality of science, but also from the past to the present because of the contingency and historicity of scientific knowledge. Copyright © 2016 Elsevier Ltd. All rights reserved.

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

Science.gov (United States)

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…

The Piney Woods School: An Exploration of the Historically Black Boarding School Experience in Shaping Student Achievement, Cultural Esteem, and Collegiate Integration

Science.gov (United States)

Alexander-Snow, Mia

2011-01-01

This qualitative case study explores the cultural impact the Piney Woods School, a historically Black independent boarding school, had on the social and academic experiences of four of its graduates in attendance at two traditionally White universities. The article discusses the collegiate experiences of four students: Samantha, Ira, Tony, and…

College Readiness: The Evaluation of Students Participating in the Historically Black College and University Program in Pre-Calculus and the Calculus Sequence

Science.gov (United States)

Hall, Angela Renee

2011-01-01

This investigative research focuses on the level of readiness of Science, Technology, Engineering, and Mathematics (STEM) students entering Historically Black Colleges and Universities (HBCU) in the college Calculus sequence. Calculus is a fundamental course for STEM courses. The level of readiness of the students for Calculus can very well play a…

Cultural Diversity and Best Practices in the Teaching and Learning of Statistics: A Faculty Perspective from A Historically Black College/University (HBCU)

Science.gov (United States)

Whaley, Arthur L.

2017-01-01

The literature on the teaching and learning of statistics tend not to address issues of cultural diversity. Twenty-nine students enrolled in a statistics course at a historically Black college/university (HBCU) were the focus of this pilot study. Using structural equation modeling (SEM), the study tested models of the effects of writing…

Black Musicians Leading the Way.

Science.gov (United States)

Music Educators Journal, 1982

1982-01-01

Describes the careers and musical achievements of Blacks who were forerunners in jazz, blues, gospel, music, spirituals, band music, classical music, ragtime, and opera. The list was compiled to provide teachers with historical background information for "Black History Month." (AM)

Educating the next generation of explorers at an historically Black University

Science.gov (United States)

Chaudhury, S.; Rodriguez, W. J.

2003-04-01

This paper describes the development of an innovative undergraduate research training model based at an Historically Black University in the USA that involves students with majors in diverse scientific disciplines in authentic Earth Systems Science research. Educating those who will be the next generation of explorers of earth and space poses several challenges at smaller academic institutions that might lack dedicated resources for this area of study. Over a 5-year span, Norfolk State University has been developing a program that has afforded the opportunity for students majoring in biology, chemistry, mathematics, computer science, physics, engineering and science education to work collaboratively in teams on research projects that emphasize the use of scientific visualization in studying the environment. Recently, a hands-on component has been added through partnerships with local K-12 school teachers in data collection and reporting for the GLOBE Program (GLobal Observations to Benefit the Environment). The successes and challenges of this program along with some innovative uses of technology to promote inquiry learning will be presented in this paper.

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

Science.gov (United States)

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…

Conference on energy research at historically black universities

Energy Technology Data Exchange (ETDEWEB)

1980-01-01

A conference was convened to present and discuss significant research and development in Historically Black Institutions (current and past); areas that show potential for inter-institutional collaboration and the sharing of facilities; existing capabilities to sustain funded research activities and future potential for expansion and enhancement; and appropriate arrangements for maximum interaction with industry and government agencies. Papers were presented at small group meetings in various energy research areas, and abstracts of the projects or programs are presented. The Solar Energy small group provided contributions in the areas of photovoltaics, biomass, solar thermal, and wind. Research reported on by the Fossil Fuel small group comprises efforts in the areas of fluidized bed combustion of coal, coal liquefaction, and oil shale pyrolysis. Five research programs reported on by the Conservation Research small group involve a summer workshop for high school students on energy conservation; use of industrial waste heat for a greenhouse; solar energy and energy conservation research and demonstration; energy efficiency and management; and a conservation program targeted at developing a model for educating low income families. The Environment Impact groups (2) presented contributions on physical and chemical impacts and biological monitors and impacts. The Policy Research group presented four papers on a careful analysis of the Equity issues; one on a model for examining the economic issue in looking at the interaction between energy technology and the state of the economy; and a second paper examined the institutional constraints on environmental oriented energy policy. Six additional abstracts by invited participants are presented. (MCW)

An Investigation of How Black STEM Faculty at Historically Black Colleges and Universities Approach the National Science Foundation Merit Review Process

Science.gov (United States)

Rankins, Falcon

This qualitative inquiry explored the ways in which US-born, Black faculty member participants in science, technology, engineering, and mathematics (STEM) disciplines at Historically Black Colleges and Universities (HBCUs) interact with the National Science Foundation (NSF). Eight Black HBCU STEM faculty members with a range of involvement in NSF-related activities were individually interviewed. Topics of discussion with participants included their prior experiences with NSF, their understanding of the merit review process, and their understanding of their personal and institutional relationships with NSF and the STEM community. Two broad findings emerged from the conversations. The first was that issues of communities and social identity were important to the participants' work as research scientists. Participants prioritized advancing people and communities over advancing the knowledge of ambiguous, disembodied scientific disciplines, and some participants were motivated by interests in social justice. However, participants maintained strong identities as scientists and the discussions provided no evidence that other social factors influenced their application of the scientific method. The second major finding dealt with the role participants perceived their institutions playing in their involvement with NSF. All participants described challenges associated with pursuing research in HBCU environments and, in some cases, the institutional challenges served as the motivation for participants' projects, with varying consequences. The participants' discussions about their institutions also raised important questions about how well-aligned participants' visions are with the visions of their institutional leadership, regarding how research should be incorporated into the HBCU mission. Finally, this study developed and refined a theoretical framework for explaining the underrepresentation of HBCUs in NSF funding streams. In developing this framework, a brief history of

Black, queer, and looking for a job: an exploratory study of career decision making among self-identified sexual minorities at an urban historically black college/university.

Science.gov (United States)

Harris, Latashia N

2014-01-01

This thematically analyzed study seeks to explore the career decision perceptions of sexual minority college students at an urban historically black college/university (HBCU). This qualitative focus group study delved into how sexual minorities feel their visible variables of race, gender expression, and degree of disclosure influence their career thought process. Theories relative to the study included Krumboltz's social learning theory of career decision-making, gender role theory, racial socialization, Cass's homosexual identity model, and impression management. Though participants initially proclaimed they did not allow their sexual minority identity to affect their career decisions, their overall responses indicated otherwise.

Black hole critical phenomena without black holes

Indian Academy of Sciences (India)

large values of Ф, black holes do form and for small values the scalar field ... on the near side of the ridge ultimately evolve to form black holes while those configu- ... The inset shows a bird's eye view looking down on the saddle point.

"It's Like Power to Move": Black Students' Psychosocial Experiences in Black Studies Courses at a Predominantly White Institution

Science.gov (United States)

Chapman-Hilliard, Collette; Beasley, Samuel T.

2018-01-01

This study examined Black students' experiences in culture-centered courses that focused on the historical and contemporary experiences of Blacks in America and across the African diaspora. Using a qualitative approach, the authors investigated the perceptions of how Black Studies courses shaped the psychosocial experiences and identity…

The Media: Views and Perceptions of Black Families.

Science.gov (United States)

Gill, Walter Arthur

This essay explores cultural differences in pictorial perception, cites historical developments and relationships of the media and the black family, and provides a basis for using educational media to effect positive self-concepts within the black family. The interpretation of representations of blacks in films, television, radio, recordings,…

Spherical domain wall formed by field dynamics of Hawking radiation and spontaneous charging-up of black hole

International Nuclear Information System (INIS)

Nagatani, Yukinori

2004-01-01

We investigate the Hawking radiation in the gauge Higgs-Yukawa theory. The ballistic model is proposed as an effective description of the system. We find that a spherical domain wall around the black hole is formed by field dynamics rather than thermal phase transition. The formation is a general property of the black hole whose Hawking temperature is equal to or greater than the energy scale of the theory. The formation of the electroweak wall and that of the GUT wall are shown. We also find a phenomenon of the spontaneous charging-up of the black hole by the wall. The Hawking radiation drives a mechanism of the charge transportation into the black hole when C- and CP-violation are assumed. The mechanism can strongly transport the hyper-charge into a black hole of the electroweak scale

The Media As Opiate: Blacks in the Performing Arts.

Science.gov (United States)

Staples, Robert

1986-01-01

It is ironic that the barometer of progress for Blacks has been their success in the performing arts. The film industry has historically shaped and reflected racist attitudes toward Blacks, while the popular music industry still segregates and exploits Black artists. (Author/GC)

Black on Yellow: Afro-Americans View Chinese-Americans, 1850-1935

Science.gov (United States)

Shankman, Arnold

1978-01-01

Using data collected from black newspapers, an explanation is sought for the unfavorable stereotypes blacks have held about Chinese Americans. Economic competition, cultural and religious differences, and blacks' belief that the Chinese were prejudiced against them are some of the historical factors mentioned which influenced black attitudes…

Ritual Black Drink consumption at Cahokia

Science.gov (United States)

Crown, Patricia L.; Emerson, Thomas E.; Gu, Jiyan; Hurst, W. Jeffrey; Pauketat, Timothy R.; Ward, Timothy

2012-01-01

Chemical analyses of organic residues in fragments of pottery from the large site of Cahokia and surrounding smaller sites in Illinois reveal theobromine, caffeine, and ursolic acid, biomarkers for species of Ilex (holly) used to prepare the ritually important Black Drink. As recorded during the historic period, men consumed Black Drink in portions of the American Southeast for ritual purification. This first demonstrated discovery of biomarkers for Ilex occurs in beaker vessels dating between A.D. 1050 and 1250 from Cahokia, located far north of the known range of the holly species used to prepare Black Drink during historic times. The association of Ilex and beaker vessels indicates a sustained ritual consumption of a caffeine-laced drink made from the leaves of plants grown in the southern United States. PMID:22869743

Super-Girl: Strength and Sadness in Black Girlhood

Science.gov (United States)

Nunn, Nia Michelle

2018-01-01

This paper complicates notions of Black girlhood by examining the dual experiences of gendered racism that result in both strength and sadness in Black girls' educational experiences. I highlight the need for a curriculum of liberation to combat historical and current social conditions negatively impacting school-aged Black girls, such as harsh…

Black lung: the social production of disease.

Science.gov (United States)

Smith, B E

1981-01-01

The black lung movement that erupted in West Virginia in 1968 was not simply a struggle for recognition of an occupational disease; it grew into a bitter controversy over who would control the definition of that disease. This article examines the historical background and medical politics of that controversy, arguing that black lung was socially produced and defined on several different levels. As a medical construct, the changing definitions of this disease can be traced to major shifts in the political economy of the coal industry. As an occupational disease, the history of black lung is internally related to the history of the workplace in which it is produced. As the object of a mass movement, black lung acquired a political definition that grew out of the collective experience of miners and their families. The definition of disease with which black lung activists challenged the medical establishment has historical roots and justification; their experience suggests that other health advocates may need to redefine the diseases they hope to eradicate.

Putting Barack Obama's Candidacy in Historical Perspective

Science.gov (United States)

Rogers, Ibram

2008-01-01

Senator Barack Obama's historic candidacy for president of the United States has generated an intense and thoughtful national discussion within Black America. His campaign has brought several issues to the fore. Recently, the author spoke with five of the most preeminent Black scholars in the nation to search out some of their thoughts on five key…

Mapping Violence, Naming Life: A History of Anti-Black Oppression in the Higher Education System

Science.gov (United States)

Mustaffa, Jalil Bishop

2017-01-01

The article will provide a historical overview of anti-Black violence in the higher education system across three time periods: Colonial Era, Post-Civil War, and the mid-to-late twentieth century. Mapping violence demands a focus on how higher education historically has practiced anti-Black oppression coupled with how Black people have practiced…

Black+Brown: Institutions of Higher Education

Science.gov (United States)

Frederick D. Patterson Research Institute, UNCF, 2014

2014-01-01

Historically Black Colleges and Universities (HBCUs) and Hispanic-Serving Institutions (HSIs) represent a small percentage of all institutions in the U.S. but educate a large portion of all black and Latino students, many of whom are low-income and first-generation college attendees. Given the population growth of these students overall, both HSIs…

White on black: can white parents teach black adoptive children how to understand and cope with racism?

Science.gov (United States)

Smith, Darron T; Juarez, Brenda G; Jacobson, Cardell K

2011-01-01

In this article, the authors examine White parents’ endeavors toward the racial enculturation and inculcation of their transracially adopted Black children. Drawing on in-depth interviews, the authors identify and analyze themes across the specific race socialization strategies and practices White adoptive parents used to help their adopted Black children to develop a positive racial identity and learn how to effectively cope with issues of race and racism. The central aim of this article is to examine how these lessons about race help to connect family members to U.S. society’s existing racial hierarchy and how these associations position individuals to help perpetuate or challenge the deeply embedded and historical structures of White supremacy. The authors use the notion of White racial framing to move outside of the traditional arguments for or against transracial adoption to instead explore how a close analysis of the adoptive parents’ racial instructions may serve as a learning tool to foster more democratic and inclusive forms of family and community.

76 FR 21946 - Proposed Collection; Comment Request for Form 990-BL; Schedule A (Form 990-BL), Form 6069

Science.gov (United States)

2011-04-19

... Initial Excise Tax Return for Black Lung Benefit Trusts and Certain Related Persons, and Form 6069, Return of Excise Tax on Excess Contributions to Black Lung Benefit Trust Under Section 4953 and Computation...: Form 990-BL, Schedule A (Form 990-BL), Information and Initial Excise Tax Return for Black Lung Benefit...

The Western Film: Holywood Myths and One Black Reality.

Science.gov (United States)

Gill, Waliyy

1986-01-01

Discusses the portrayal of Blacks in American Western films since the first Western was made in 1903. Also describes the changing social and historical context of the film industry as related to Blacks. (GC)

Black Women in the Academy: The Secrets to Success and Achievement.

Science.gov (United States)

Gregory, Sheila T.

This book presents selected historical data focusing on three aspects in the lives of Black women: resilience of Black women and their families; strengths of the Black church and community; and formidable gains made by Black women in the workforce. The status and achievements of Black women professors and scholars in the academy are reviewed, with…

British Dance: Black Routes

OpenAIRE

Adair, C.; Burt, Ramsay, 1953-

2016-01-01

British Dance: Black Routes re-examines the distinctive contributions made to British dance by dancers who are Black. Covering the period 1946 to the present, it presents a radical re-reading of dancers and their companies, placing their achievements within a broader historical, cultural and artistic context. The result of a two year research project, British Dance and the African Diaspora, led by editors Christy Adair and Ramsay Burt, the collection looks at artists working with contempor...

A Link to the Future: A Pilot Study Look at How Historically Black Colleges and Universities with Journalism and Mass Communications Units Use the Internet in Recruiting

Science.gov (United States)

Crawford, Jerry, II

2012-01-01

Historically Black Colleges and Universities (HBCUs) have had the ability to recruit African-American students since the 1860s by stressing a sense of inclusion and family through their mission statements and community outreach. There was little to no competition for African-American students from predominantly white institutions until integration…

The Black Teacher Shortage: A Literature Review of Historical and Contemporary Trends

Science.gov (United States)

Madkins, Tia C.

2011-01-01

Desegregation marked the beginning of a long period of loss of Black teachers within the profession. First, Black teachers were not hired in desegregated schools, and then as other professional opportunities opened up in society, fewer Blacks entered the teacher pipeline. The purpose of this literature review is to synthesize research relevant to…

The Precarious Question of Black Cultural Centers Versus Multicultural Centers.

Science.gov (United States)

Princes, Carolyn D. W.

This paper discusses the role of black cultural centers on university campuses, focusing on whether black cultural centers or multicultural centers best meet the needs of an increasingly diverse student body and society. It examines the historical role of black cultural centers as vehicles to promote educational opportunity, student retention, and…

Black, White, and Biracial Students' Engagement at Differing Institutional Types

Science.gov (United States)

Harris, Jessica C.; BrckaLorenz, Allison

2017-01-01

Within this study, the authors are interested in engagement practices for Black students, White students, and the mixed-race college student population at Historically Black Colleges and Universities (HBCUs) and non-HBCUs. The authors asked the following research questions: How does engagement compare for Black, White, and biracial students with…

Black Swan Tropical Cyclones

Science.gov (United States)

Emanuel, K.; Lin, N.

2012-12-01

Virtually all assessments of tropical cyclone risk are based on historical records, which are limited to a few hundred years at most. Yet stronger TCs may occur in the future and at places that have not been affected historically. Such events lie outside the realm of historically based expectations and may have extreme impacts. Their occurrences are also often made explainable after the fact (e.g., Hurricane Katrina). We nickname such potential future TCs, characterized by rarity, extreme impact, and retrospective predictability, "black swans" (Nassim Nicholas Taleb, 2007). As, by definition, black swan TCs have yet to happen, statistical methods that solely rely on historical track data cannot predict their occurrence. Global climate models lack the capability to predict intense storms, even with a resolution as high as 14 km (Emanuel et al. 2010). Also, most dynamic downscaling methods (e.g., Bender et al. 2010) are still limited in horizontal resolution and are too expensive to implement to generate enough events to include rare ones. In this study, we apply a simpler statistical/deterministic hurricane model (Emanuel et al. 2006) to simulate large numbers of synthetic storms under a given (observed or projected) climate condition. The method has been shown to generate realistic extremes in various basins (Emanuel et al. 2008 and 2010). We also apply a hydrodynamic model (ADCIRC; Luettich et al. 1992) to simulate the storm surges generated by these storms. We then search for black swan TCs, in terms of the joint wind and surge damage potential, in the generated large databases. Heavy rainfall is another important TC hazard and will be considered in a future study. We focus on three areas: Tampa Bay in the U.S., the Persian Gulf, and Darwin in Australia. Tampa Bay is highly vulnerable to storm surge as it is surrounded by shallow water and low-lying lands, much of which may be inundated by a storm tide of 6 m. High surges are generated by storms with a broad

Aerial Photography and Imagery, Ortho-Corrected, Historic 1958 black and white aerial photography for Wicomico County, Maryland. Imagery was scanned from historic hard copy images and georeferenced to current imagery. This data is available via map service., Published in 2010, 1:12000 (1in=1000ft) scale, Eastern Shore Regional GIS Cooperative.

Data.gov (United States)

NSGIC Regional | GIS Inventory — Aerial Photography and Imagery, Ortho-Corrected dataset current as of 2010. Historic 1958 black and white aerial photography for Wicomico County, Maryland. Imagery...

Assessment of the DOE/NREL Historically Black College and University Photovoltaic Research Associates Program

Energy Technology Data Exchange (ETDEWEB)

Posey-Eddy, F.; McConnell, R. D.

2002-08-01

This report details the DOE/NREL Historically Black College and University (HBCU) Photovoltaic Research Associates Program, a small but remarkable program that directly affected dozens of minority undergraduate students in ways that changed many of their lives. The progress and accomplishments of undergraduates within the nine participating universities were monitored and assessed through their presentations at an annual NREL-sponsored HBCU conference. Although the funding was small, typically $400,000 per year, the money made a significant impact. The best students sometimes went on to the nation's top graduate schools (e.g., MIT) or important management positions in large companies. Other students had opportunities to learn how renewable energy could positively affect their lives and their neighbors' lives. A few were lucky enough to install photovoltaic lighting and water-pumping systems in Africa, and to see and feel firsthand the technical and emotional benefits of this technology for families and villages. Two of the schools, Texas Southern University and Central State University, were particularly successful in leveraging their DOE/NREL funding to obtain additional funding for expanded programs.

Touchdowns and Honor Societies: Expanding the Focus of Black Male Excellence

Science.gov (United States)

Morris, Jerome E.; Adeyemo, Adeoye O.

2012-01-01

The athletic/academic paradox for black males is historically rooted in rank-and-file notions of black people primarily as workers rather than thinkers. Policymakers, educators, and administrators should think more deeply about how societal perceptions of black males as "natural" athletes, rather than intelligent students adversely influences how…

Unpacking Pat Parker: Intersections and Revolutions in "Movement in Black".

Science.gov (United States)

Washburn, Amy

2015-01-01

This article explores Pat Parker's poem "Movement in Black." It examines the ways in which she emblematizes intersectionality and simultaneity as forms of revolution in struggles of self and society. It begins with a theoretical and historical apparatus to contextualize Parker as an artist and activist. Then it offers a literary analysis of the poem, focusing on themes of time and space, marginalization and movement, difference and power, visibility and invisibility, and history and memory. It argues that Parker uses autobiographical writing to fuse personal and political sites of resistance.

A Review of Our Roots: Blacks in Gerontology

Science.gov (United States)

Brown, Candace S.; Baker, Tamara A.; Mingo, Chivon A.; Harden, J. Taylor; Whitfield, Keith; Aiken-Morgan, Adrienne T.; Phillips, Karon L.; Washington, Tiffany

2014-01-01

The historical underpinnings in the field of gerontology rest on the contributions of scholars across a myriad of racial and ethnic backgrounds. With the increasing diversity of the adult population, there is a need to increase the number of researchers who study older adults from diverse racial and ethnic populations in general and Black elderly people in particular. Furthermore, it is important to document the participation of Black older adults in our earliest and continuing research efforts. Understanding the historical context and the foundational influence of Black scholars in this field is critical. To realize its humble beginnings, one must become aware of the contributions by Black scholars who have a vested interest in the aging process. With universal similarities and unique differences among older adults, there is a need to acknowledge the past and current scholarship of those who study the aging processes of Blacks while marveling over the future possibilities. The purpose of this review is to elucidate the legacy and current contributions, philosophies, and research of Black scholars in the field of gerontology. In addition, exploration of the theoretical and conceptual frameworks used to establish national and organizational initiatives is reviewed. The impetus in initiating and continuing this work requires a “knowledge of our roots” while moving into the future. It is important to learn the history and significance of Black scholars in gerontology, the contributions of older Blacks, and appreciate the resiliency and marveled life course of this unique population. PMID:24022695

The Historically Black Colleges and Universities/Minority Institutions Environmental Technology Consortium annual report draft, 1995--1996

Energy Technology Data Exchange (ETDEWEB)

NONE

1998-07-01

The HBCU/MI ET Consortium was established in January 1990, through a memorandum of Understanding (MOU) among its member institutions. This group of research-oriented Historically Black Colleges and Universities and Minority Institutions (HBCUs/MIs) agreed to work together to initiate or revise educational programs, develop research partnerships with public and private sector organizations, and promote technology development and transfer to address the nation`s critical environmental problems. While the Consortium`s Research, Education and Technology Transfer (RETT) Plan is the cornerstone of its overall program efforts, the initial programmatic activities of the Consortium focused on environmental education at all levels with the objective of addressing the underrepresentation of minorities in the environmental professions. This 1996 Annual Report provides an update on the activities of the Consortium with a focus on environmental curriculum development for the Technical Qualifications Program (TQP) and Education for Sustainability.

Gendered racism and the sexual and reproductive health of Black and Latina Women.

Science.gov (United States)

Rosenthal, Lisa; Lobel, Marci

2018-02-15

To understand health disparities, it is important to use an intersectional framework that examines unique experiences of oppression faced by particular groups due to their intersecting identities and social positions linked to societal structures. We focus on Black and Latina women and their experiences with 'gendered racism' - unique forms of oppression due to the intersection of race/ethnicity and gender - to foster understanding of disparities between Black and Latina versus White women in sexual and reproductive health outcomes in the U.S. Specifically, we focus on stereotype-related gendered racism (ongoing discrimination and stereotype threat based on historically-rooted stereotypes about Black and Latina women's sexuality and motherhood) and birth control-related mistrust (ongoing mistrust of the government and medical system related to birth control due to historical and current abuses). We analyzed data from two survey studies with adult women in New York (Study 1: paper-and-pencil community data collection, N = 135, M age  = 43.35) and across the U.S. (Study 2: online data collection, N = 343, M age  = 29.49) who were currently pregnant or had at least one child and identified as Black, Latina, or White. Black and Latina women reported greater frequency of and concern over stereotype-related gendered racism (F(3,131) = 17.90, p stereotype-related gendered racism was positively associated with pregnancy-specific stress (ß = .40, p gendered racism may play an important role in existing racial/ethnic disparities in women's sexual and reproductive health outcomes, and interventions addressing gendered racism at multiple levels are needed to promote health equity.

Historical Dialectics of Black Nationalist Movements in America.

Science.gov (United States)

Turner, James E.

1977-01-01

The development of Africa-oriented social movements is divided into five periods: (1) the genesis of the return-to-Africa movement, 1790-1840; (2) the quest for nationality, 1845-1861; (3) the roots of Pan-Africanism, 1870-1915; (4) the Garvey movement, 1916-1930; and (5) the recent Black liberation movement, inspired by Malcolm X and operating in…

Black Artists' Music Videos: Three Successful Strategies

Science.gov (United States)

Peterson-Lewis, Sonja; Chennault, Shirley A.

1986-01-01

Identifies three successful self-presentational patterns used by black artists to penetrate the music television market. Discusses the historical relationship between minorities and the mass media. (MS)

On the Ontogeny of Display Behaviour in the Black-Headed Gull : I. The Gradual Emergence of the Adult Forms

NARCIS (Netherlands)

Groothuis, Ton

1989-01-01

The central question in this paper concerns the mechanism by which displays develop their species-specific sterotyped form. To this end the ontogeny of display behaviour in the black-headed gull was studied in birds kept and raised in aviaries. First it was analyzed whether the complete adult form

Suburban Black Lives Matter

Science.gov (United States)

Lewis-McCoy, R. L'Heureux

2018-01-01

This article explores the range of experiences and meanings of Black life in suburban space. Drawing from educational, historical, and sociological literatures, I argue that an underconsideration of suburban space has left many portraits of educational inequality incomplete. The article outlines the emergence of American suburbs and the formation…

Advantages of using microbial technology over traditional chemical technology in removal of black crusts from stone surfaces of historical monuments.

Science.gov (United States)

Cappitelli, Francesca; Toniolo, Lucia; Sansonetti, Antonio; Gulotta, Davide; Ranalli, Giancarlo; Zanardini, Elisabetta; Sorlini, Claudia

2007-09-01

This study compares two cleaning methods, one involving an ammonium carbonate-EDTA mixture and the other involving the sulfate-reducing bacterium Desulfovibrio vulgaris subsp. vulgaris ATCC 29579, for the removal of black crust (containing gypsum) on marble of the Milan Cathedral (Italy). In contrast to the chemical cleaning method, the biological procedure resulted in more homogeneous removal of the surface deposits and preserved the patina noble under the black crust. Whereas both of the treatments converted gypsum to calcite, allowing consolidation, the chemical treatment also formed undesirable sodium sulfate.

Advantages of Using Microbial Technology over Traditional Chemical Technology in Removal of Black Crusts from Stone Surfaces of Historical Monuments▿

Science.gov (United States)

Cappitelli, Francesca; Toniolo, Lucia; Sansonetti, Antonio; Gulotta, Davide; Ranalli, Giancarlo; Zanardini, Elisabetta; Sorlini, Claudia

2007-01-01

This study compares two cleaning methods, one involving an ammonium carbonate-EDTA mixture and the other involving the sulfate-reducing bacterium Desulfovibrio vulgaris subsp. vulgaris ATCC 29579, for the removal of black crust (containing gypsum) on marble of the Milan Cathedral (Italy). In contrast to the chemical cleaning method, the biological procedure resulted in more homogeneous removal of the surface deposits and preserved the patina noble under the black crust. Whereas both of the treatments converted gypsum to calcite, allowing consolidation, the chemical treatment also formed undesirable sodium sulfate. PMID:17601804

A Brief History of Black Holes

Directory of Open Access Journals (Sweden)

Crothers S. J.

2006-04-01

Full Text Available Neither the layman nor the specialist, in general, have any knowledge of the historical circumstances underlying the genesis of the idea of the Black Hole. Essentially, almost all and sundry simply take for granted the unsubstantiated allegations of some ostentatious minority of the relativists. Unfortunately, that minority has been rather careless with the truth and is quite averse to having its claims corrected, notwithstanding the documentary evidence on the historical record. Furthermore, not a few of that vainglorious and disingenuous coterie, particularly amongst those of some notoriety, attempt to dismiss the testimony of the literature with contempt, and even deliberate falsehoods, claiming that history is of no importance. The historical record clearly demonstrates that the Black Hole has been conjured up by combination of confusion, superstition and ineptitude, and is sustained by widespread suppression of facts, both physical and theoretical. The following essay provides a brief but accurate account of events, verifiable by reference to the original papers, by which the scandalous manipulation of both scientific and public opinion is revealed

Black Males and Television: New Images Versus Old Stereotypes.

Science.gov (United States)

Douglas, Robert L.

1987-01-01

This paper focuses on historic portrayal of black males in service and support roles in the media and their relation to social reality. Both television and films use glamorous sophisticated trappings seemingly to enhance the image of black males, but the personalities of the characters they play remain stereotypic. (VM)

Pilot Design and Implementation of an Innovative Mental Health and Wellness Clinic at a Historically Black College/University.

Science.gov (United States)

Moore, Jessica R; Pollio, David E; Hong, Barry A; Valencia, Celeste; Sorrell, Michael; North, Carol S

2018-05-01

A pilot mental health and wellness clinic was developed and implemented on the campus of Paul Quinn College, a small Historically Black College and University (HBCU) in Dallas, TX, to address mental health disparities in an African-American student population. Additionally, a series of student engagement activities was developed and implemented to address stigma and enhance linkage to the clinic. The student engagement activities were well attended. In all, 14 students requested a total of 97 appointments during the spring 2016 semester, but attended only 41 appointments. Students sought treatment of a variety of psychiatric disorders, most commonly major depressive disorder and adjustment disorder. A model based on this program could conceivably be extended to serve students more broadly in other HBCUs as well as in community colleges.

The Historically Black Colleges and Universities/Minority Institutions Environmental Technology and Waste Management Consortium annual report, 1990--1991

Energy Technology Data Exchange (ETDEWEB)

NONE

1991-12-31

The HBCU/MI Environmental Technology and Waste Management Consortium was established in January 1990, through a Memorandum of Understanding (MOU) among the member institutions. This group of research-oriented Historically Black Colleges and Universities and Minority Institutions (HBCU/MI) agreed to work together to initiate research, technology development and education programs to address the nation`s critical environmental problems. As a group the HBCU/MI Consortium is uniquely positioned to reach women and the minority populations of African Americans, Hispanics and American Indians. As part of their initial work, they developed the Research, Education, and Technology Transfer (RETT) Plan to actualize the Consortium`s guiding principles. In addition to developing a comprehensive research agenda, four major programs were begun to meet these goals. This report summarizes the 1990--1991 progress.

Socioeconomic Factors Affecting Local Support for Black Bear Recovery Strategies(AED)

Science.gov (United States)

There is global interest in recovering locally extirpated carnivore species. Successful efforts to recover Louisiana black bear in Louisiana have prompted interest in recovery throughout the species’ historical range. We evaluated support for three potential black bear recovery s...

The Historically Black Colleges and Universities/Minority Institutions Environmental Technology Consortium annual report 1994--1995

Energy Technology Data Exchange (ETDEWEB)

NONE

1998-07-01

The HBCU/MI ET Consortium was established in January 1990, through a Memorandum of Understanding (MOU) among its member institutions. This group of research oriented Historically Black Colleges and Universities and Minority Institutions (HBCU/MIs) agreed to work together to initiate or revise education programs, develop research partnerships with public and private sector organizations, and promote technology development to address the nation`s critical environmental contamination problems. The Consortium`s Research, Education and Technology Transfer (RETT) Plan became the working agenda. The Consortium is a resource for collaboration among the member institutions and with federal an state agencies, national and federal laboratories, industries, (including small businesses), majority universities, and two and four-year technical colleges. As a group of 17 institutions geographically located in the southern US, the Consortium is well positioned to reach a diverse group of women and minority populations of African Americans, Hispanics and American Indians. This Report provides a status update on activities and achievements in environmental curriculum development, outreach at the K--12 level, undergraduate and graduate education, research and development, and technology transfer.

Black hole — never forms, or never evaporates

International Nuclear Information System (INIS)

Sun, Yi

2011-01-01

Many discussion about the black hole conundrums, such like singularity and information loss, suggested that there must be some essential irreconcilable conflict between quantum theory and classical gravity theory, which cannot be solved with any semiclassical quantized model of gravity, the only feasible way must be some complete unified quantum theory of gravity. In Vachaspati, the arguments indicate the possibility of an alternate outcome of gravitational collapse which avoids the information loss problem. In this paper, also with semiclassical analysis, it shows that so long as the mechanism of black hole evaporation satisfies a quite loose condition that the evaporation lifespan is finite for external observers, regardless of the detailed mechanism and process of evaporation, the conundrums above can be naturally avoided. This condition can be satisfied with Hawking-Unruh mechanism. Thus, the conflict between quantum theory and classical gravity theory may be not as serious as it seemed to be, the effectiveness of semiclassical methods might be underestimated. An exact universal solution with spherical symmetry of Einstein field equation has been derived in this paper. All possible solutions with spherical symmetry of Einstein field equation are its special cases. In addition, some problems of the Penrose diagram of an evaporating black hole first introduced by Hawking in 1975 are clarified

External Labor Markets and the Distribution of Black Scientists and Engineers in Academia.

Science.gov (United States)

Kulis, Stephen; Shaw, Heather; Chong, Yinong

2000-01-01

Analyzes data from the 1989 Survey of Doctorate Recipients to evaluate racial segmentation of the academic labor market along geographic and disciplinary lines. Finds that black faculty in the sciences and engineering are found disproportionately in southern, historically black institutions; areas with sizable black populations; and, independent…

Obesity among Black Adolescent Girls: Genetic, Psychosocial, and Cultural Influences

Science.gov (United States)

Alleyne, Sylvan I.; LaPoint, Velma

2004-01-01

This article focuses on the causes, consequences, and prevention of obesity among a subgroup of the American population, Black adolescent girls. Using an ecological perspective on obesity among Black adolescent girls, including feminist-womanist perspectives and historical and medical sociological perspectives, the authors discuss genetic,…

Historical analysis of Newfoundland dog fur colour genetics

Directory of Open Access Journals (Sweden)

J. Bondeson

2015-06-01

Full Text Available This article makes use of digitized historic newspapers to analyze Newfoundland dog fur colour genetics, and fur colour variations over time. The results indicate that contrary to the accepted view, the ‘Solid’ gene was introduced into the British population of Newfoundland dogs in the 1840s. Prior to that time, the dogs were white and black (Landseer or white and brown, and thus spotted/spotted homozygotes. Due to ‘Solid’ being dominant over ‘spotted’, and selective breeding, today the majority of Newfoundland dogs are solid black. Whereas small white marks on the chest and/or paw appears to be a random event, the historical data supports the existence of an ‘Irish spotted’ fur colour pattern, with white head blaze, breast, paws and tail tip, in spotted/spotted homozygotes.

Satellite-Observed Black Water Events off Southwest Florida: Implications for Coral Reef Health in the Florida Keys National Marine Sanctuary

Directory of Open Access Journals (Sweden)

Brian Lapointe

2013-01-01

Full Text Available A “black water” event, as observed from satellites, occurred off southwest Florida in 2012. Satellite observations suggested that the event started in early January and ended in mid-April 2012. The black water patch formed off central west Florida and advected southward towards Florida Bay and the Florida Keys with the shelf circulation, which was confirmed by satellite-tracked surface drifter trajectories. Compared with a previous black water event in 2002, the 2012 event was weaker in terms of spatial and temporal coverage. An in situ survey indicated that the 2012 black water patch contained toxic K. brevis and had relatively low CDOM (colored dissolved organic matter and turbidity but high chlorophyll-a concentrations, while salinity was somewhat high compared with historical values. Further analysis revealed that the 2012 black water was formed by the K. brevis bloom initiated off central west Florida in late September 2011, while river runoff, Trichodesmium and possibly submarine groundwater discharge also played important roles in its formation. Black water patches can affect benthic coral reef communities by decreasing light availability at the bottom, and enhanced nutrient concentrations from black water patches support massive macroalgae growth that can overgrow coral reefs. It is thus important to continue the integrated observations where satellites provide synoptic and repeated observations of such adverse water quality events.

Leadership, Governance, and Sustainability of Black Colleges and Universities

Science.gov (United States)

Ezzell, Jack L., Jr.; Schexnider, Alvin J.

2010-01-01

A topic of continuing interest in American higher education and society is the future of historically black colleges and universities, commonly referred to as HBCUs. The nation's public and private black institutions of higher education have proved their mettle, and yet they face persistent challenges to survive. A huge part of the challenge black…

Coming to UCT: Black Students, Transformation and Discourses of Race

Science.gov (United States)

Kessi, Shose; Cornell, Josephine

2015-01-01

Since the dismantling of apartheid in South Africa, increasing numbers of black students have been enrolling at historically whites-only universities. This situation has been paralleled by a resurgence of racialising discourses that represent black students as lacking in competencies, lowering academic standards and undeserving of their places at…

Black Students in Protest: A Study of the Origins of the Black Student Movement. The Arnold and Caroline Rose Monograph Series in Sociology.

Science.gov (United States)

Orum, Anthony M.

The present study is a sociological rather than an historical treatment of the role of black college students in the civil rights movement. We will determine the characteristic motivation of the typical black student protestor as well as the social and economic conditions that provoked him to protest. The data for our analysis will consist…

Bird specimens track 135 years of atmospheric black carbon and environmental policy

Science.gov (United States)

DuBay, Shane G.; Fuldner, Carl C.

2017-10-01

Atmospheric black carbon has long been recognized as a public health and environmental concern. More recently, black carbon has been identified as a major, ongoing contributor to anthropogenic climate change, thus making historical emission inventories of black carbon an essential tool for assessing past climate sensitivity and modeling future climate scenarios. Current estimates of black carbon emissions for the early industrial era have high uncertainty, however, because direct environmental sampling is sparse before the mid-1950s. Using photometric reflectance data of >1,300 bird specimens drawn from natural history collections, we track relative ambient concentrations of atmospheric black carbon between 1880 and 2015 within the US Manufacturing Belt, a region historically reliant on coal and dense with industry. Our data show that black carbon levels within the region peaked during the first decade of the 20th century. Following this peak, black carbon levels were positively correlated with coal consumption through midcentury, after which they decoupled, with black carbon concentrations declining as consumption continued to rise. The precipitous drop in atmospheric black carbon at midcentury reflects policies promoting burning efficiency and fuel transitions rather than regulating emissions alone. Our findings suggest that current emission inventories based on predictive modeling underestimate levels of atmospheric black carbon for the early industrial era, suggesting that the contribution of black carbon to past climate forcing may also be underestimated. These findings build toward a spatially dynamic emission inventory of black carbon based on direct environmental sampling.

Low-mass black holes as the remnants of primordial black hole formation.

Science.gov (United States)

Greene, Jenny E

2012-01-01

Bridging the gap between the approximately ten solar mass 'stellar mass' black holes and the 'supermassive' black holes of millions to billions of solar masses are the elusive 'intermediate-mass' black holes. Their discovery is key to understanding whether supermassive black holes can grow from stellar-mass black holes or whether a more exotic process accelerated their growth soon after the Big Bang. Currently, tentative evidence suggests that the progenitors of supermassive black holes were formed as ∼10(4)-10(5) M(⊙) black holes via the direct collapse of gas. Ongoing searches for intermediate-mass black holes at galaxy centres will help shed light on this formation mechanism.

Recombinant F1-V fusion protein protects black-footed ferrets (Mustela nigripes) against virulent Yersinia pestis infection

Science.gov (United States)

Rocke, Tonie E.; Mencher, J.; Smith, Susan; Friedlander, A.M.; Andrews, G.P.; Baeten, L.A.

2004-01-01

Black-footed ferrets (Mustela nigripes) are highly susceptible to sylvatic plague, caused by the bacterium Yersinia pestis, and this disease has severely hampered efforts to restore ferrets to their historic range. A study was conducted to assess the efficacy of vaccination of black-footed ferrets against plague using a recombinant protein vaccine, designated F1-V, developed by personnel at the U.S. Army Medical Research Institute of Infectious Diseases. Seven postreproductive black-footed ferrets were immunized with the vaccine, followed by two booster immunizations on days 23 and 154; three control black-footed ferrets received a placebo. After the second immunization, antibody titers to both F1 and V antigen were found to be significantly higher in vaccinates than controls. On challenge with 7,800 colony-forming units of virulent plague by s.c. injection, the three control animals died within 3 days, but six of seven vaccinates survived with no ill effects. The seventh vaccinate died on day 8. These results indicate that black-footed ferrets can be immunized against plague induced by the s.c. route, similar to fleabite injection.

Know Your Role: Black College Students, Racial Identity, and Performance

Science.gov (United States)

Stewart, Dafina-Lazarus

2015-01-01

This article is a report of a critical constructivist study of racial identity and performance among 13 Black, traditional-age students enrolled at three different colleges, two historically Black and one predominantly White. The study's approach understood identity to be socially constructed and reliant upon community affirmation and validation.…

Black Womanhood and Feminist Standpoints.

Science.gov (United States)

Allen, Brenda J.

1998-01-01

Discusses challenges and consequences of being a member of two historically oppressed groups in the United States--Blacks and females. Relies on feminist standpoint theory--a distinctive element of contemporary feminist thought about how knowledge is constructed. Focuses on academe as a discursive site for constructing identity. (PA)

Experiences of Black MSM at an HBCU Regarding Stigma and HIV Risk Behavior

Science.gov (United States)

Jeter, Natasha Harden

2016-01-01

Black men who have sex with men (MSM) on Historically Black College/University (HBCU) campuses face a unique set of challenges. In addition to being disproportionately affected by HIV, Black MSM are impacted by risk behavior, stigma, and environmental policies and practices that adversely influence their experiences. The purpose of this study was…

Using Focus Groups to Explore the Stressful Life Events of Black College Men

Science.gov (United States)

Watkins, Daphne C.; Green, B. Lee; Goodson, Patricia; Guidry, Jeffrey Joseph; Stanley, Christine A.

2007-01-01

Black students who attend predominately White institutions (PWI) face many obstacles. This study identified the stressful life events of Black college men via focus group discussions and examined how these events impact their mental health and health behaviors. Forty-six participants from a PWI and a historically Black college/university (HBCU)…

Historical sources of black carbon identified by PAHs and δ13C in Sanjiang Plain of Northeastern China

Science.gov (United States)

Gao, Chuanyu; Liu, Hanxiang; Cong, Jinxin; Han, Dongxue; Zhao, Winston; Lin, Qianxin; Wang, Guoping

2018-05-01

Black carbon (BC), the byproduct of incomplete combustion of fossil fuels and biomass can be stored in soil for a long time and potentially archive changes in natural and human activities. Increasing amounts of BC has been produced from human activities during the past 150 years and has influenced global climate change and carbon cycle. Identifying historical BC sources is important in knowing how historical human activities influenced BC and BC transportation processes in the atmosphere. In this study, PAH components and δ13C-BC in peatland in the Sanjiang Plain were used for identifying and verifying regional BC sources during the last 150 years. Results showed that environment-unfriendly industry developed at the end of the 1950s produced a great amount of BC and contributed the most BC in this period. In other periods, however, BC in the Sanjiang Plain was mainly produced from incomplete biomass burning before the 1990s; particularly, slash-and-burn of pastures and forests during regional reclamation periods between the 1960s and 1980s produced a huge amount of biomass burning BC, which then deposited into the surrounding ecosystems. With the regional reclamation decreasing and environment-friendly industry developing, the proportion of BC emitted and deposited from transportation sources increased and transportation source became an important BC source in the Sanjiang Plain after the 1990s.

Teaching Celia in the Age of Black Lives Matter

OpenAIRE

Brandon R. Byrd

2016-01-01

The emergence of Black Lives Matter has introduced a language of black liberation to a new generation of students. In doing so, it has provided an opportunity for historical study. Teacher-scholars can and should take advantage of the renewed interest in systemic threats to black life in the United States when teaching about past victims of state-sanctioned violence including Celia, an enslaved teenager executed for killing her master after years of sexual abuse. In doing so, they can not onl...

SUPERMASSIVE BLACK HOLES IN A STAR-FORMING GASEOUS CIRCUMNUCLEAR DISK

Energy Technology Data Exchange (ETDEWEB)

Del Valle, L.; Escala, A.; Molina, J. [Departamento de Astronomía, Universidad de Chile (Chile); Maureira-Fredes, C.; Amaro-Seoane, P. [Max Planck Institut fur Gravitationsphysik (Albert-Einstein-Institut), D-14476 Potsdam (Germany); Cuadra, J., E-mail: ldelvalleb@gmail.com [Instituto de Astrofísica, Pontificia Universidad Catolica de Chile (Chile)

2015-09-20

Using N-body/smoothed particle hydrodynamics simulations we study the evolution of the separation of a pair of supermassive black holes (SMBHs) embedded in a star-forming circumnuclear disk (CND). This type of disk is expected to be formed in the central kiloparsec of the remnant of gas-rich galaxy mergers. Our simulations indicate that orbital decay of the SMBHs occurs more quickly when the mean density of the CND is higher, due to increased dynamical friction. However, in simulations where the CND is fragmented in high-density gaseous clumps (clumpy CND), the orbits of the SMBHs are erratically perturbed by the gravitational interaction with these clumps, delaying, in some cases, the orbital decay of the SMBHs. The densities of these gaseous clumps in our simulations and in recent studies of clumpy CNDs are two orders of magnitude higher than the observed density of molecular clouds in isolated galaxies or ultraluminous infrared galaxies (ULIRGs), thus, we expect that SMBH orbits are perturbed less in real CNDs than in the simulated CNDs of this study and other recent studies. We also find that the migration timescale has a weak dependence on the star formation rate of the CND. Furthermore, the migration timescale of an SMBH pair in a star-forming clumpy CND is at most a factor of three longer than the migration timescale of a pair of SMBHs in a CND modeled with more simple gas physics. Therefore, we estimate that the migration timescale of the SMBHs in a clumpy CND is on the order of 10{sup 7} years.

Teaching Celia in the Age of Black Lives Matter

Directory of Open Access Journals (Sweden)

Brandon R. Byrd

2016-11-01

Full Text Available The emergence of Black Lives Matter has introduced a language of black liberation to a new generation of students. In doing so, it has provided an opportunity for historical study. Teacher-scholars can and should take advantage of the renewed interest in systemic threats to black life in the United States when teaching about past victims of state-sanctioned violence including Celia, an enslaved teenager executed for killing her master after years of sexual abuse. In doing so, they can not only draw useful connections between the past and present but also lay the foundations for a more meaningful study of black radicalism and black resistance in the United States.

"Losing an Arm": Schooling as a Site of Black Suffering

Science.gov (United States)

Dumas, Michael J.

2014-01-01

Drawing on data from a historical-ethnographic study of the cultural politics of school desegregation in Seattle, USA, the author explores suffering as a recurring theme in the narratives of four black leaders, educators and activists involved in the struggle for black educational opportunity in that city during the post-Civil Rights Era. As these…

Multiple geographic origins of commensalism and complex dispersal history of Black Rats.

Science.gov (United States)

Aplin, Ken P; Suzuki, Hitoshi; Chinen, Alejandro A; Chesser, R Terry; Ten Have, José; Donnellan, Stephen C; Austin, Jeremy; Frost, Angela; Gonzalez, Jean Paul; Herbreteau, Vincent; Catzeflis, Francois; Soubrier, Julien; Fang, Yin-Ping; Robins, Judith; Matisoo-Smith, Elizabeth; Bastos, Amanda D S; Maryanto, Ibnu; Sinaga, Martua H; Denys, Christiane; Van Den Bussche, Ronald A; Conroy, Chris; Rowe, Kevin; Cooper, Alan

2011-01-01

The Black Rat (Rattus rattus) spread out of Asia to become one of the world's worst agricultural and urban pests, and a reservoir or vector of numerous zoonotic diseases, including the devastating plague. Despite the global scale and inestimable cost of their impacts on both human livelihoods and natural ecosystems, little is known of the global genetic diversity of Black Rats, the timing and directions of their historical dispersals, and the risks associated with contemporary movements. We surveyed mitochondrial DNA of Black Rats collected across their global range as a first step towards obtaining an historical genetic perspective on this socioeconomically important group of rodents. We found a strong phylogeographic pattern with well-differentiated lineages of Black Rats native to South Asia, the Himalayan region, southern Indochina, and northern Indochina to East Asia, and a diversification that probably commenced in the early Middle Pleistocene. We also identified two other currently recognised species of Rattus as potential derivatives of a paraphyletic R. rattus. Three of the four phylogenetic lineage units within R. rattus show clear genetic signatures of major population expansion in prehistoric times, and the distribution of particular haplogroups mirrors archaeologically and historically documented patterns of human dispersal and trade. Commensalism clearly arose multiple times in R. rattus and in widely separated geographic regions, and this may account for apparent regionalism in their associated pathogens. Our findings represent an important step towards deeper understanding the complex and influential relationship that has developed between Black Rats and humans, and invite a thorough re-examination of host-pathogen associations among Black Rats.

Historic and Cultural Roots of Apartheid.

Science.gov (United States)

Chonco, Seshi

1987-01-01

Reviews the historical and cultural roots of the South African system of apartheid. Covers early Dutch settlement, the Anglo-Boer War, the Native Land Act of 1913, and the rise of the National Party. Concludes with a discussion of the different perspectives held by black and white South Africans on the "progress" made in recent years.…

Black-spot poison ivy.

Science.gov (United States)

Schram, Sarah E; Willey, Andrea; Lee, Peter K; Bohjanen, Kimberly A; Warshaw, Erin M

2008-01-01

In black-spot poison ivy dermatitis, a black lacquerlike substance forms on the skin when poison ivy resin is exposed to air. Although the Toxicodendron group of plants is estimated to be the most common cause of allergic contact dermatitis in the United States, black-spot poison ivy dermatitis is relatively rare.

HMI - historical flashback

International Nuclear Information System (INIS)

Weiss, B.

1993-01-01

This brochure is based on a paper read at a HMI colloquium on 14 Juni 1993. The historical information is based on a detailed historical study published in book form under the title ''Industrial-scale Research in Berlin''. (orig./HSCH) [de

Statistical black-hole thermodynamics

International Nuclear Information System (INIS)

Bekenstein, J.D.

1975-01-01

Traditional methods from statistical thermodynamics, with appropriate modifications, are used to study several problems in black-hole thermodynamics. Jaynes's maximum-uncertainty method for computing probabilities is used to show that the earlier-formulated generalized second law is respected in statistically averaged form in the process of spontaneous radiation by a Kerr black hole discovered by Hawking, and also in the case of a Schwarzschild hole immersed in a bath of black-body radiation, however cold. The generalized second law is used to motivate a maximum-entropy principle for determining the equilibrium probability distribution for a system containing a black hole. As an application we derive the distribution for the radiation in equilibrium with a Kerr hole (it is found to agree with what would be expected from Hawking's results) and the form of the associated distribution among Kerr black-hole solution states of definite mass. The same results are shown to follow from a statistical interpretation of the concept of black-hole entropy as the natural logarithm of the number of possible interior configurations that are compatible with the given exterior black-hole state. We also formulate a Jaynes-type maximum-uncertainty principle for black holes, and apply it to obtain the probability distribution among Kerr solution states for an isolated radiating Kerr hole

Why Not Academia?--The Streamlined Career Choice Process of Black African Women Engineers: A Grounded Theory Study

Science.gov (United States)

Mlambo, Yeukai Angela

2017-01-01

Black African women are grossly underrepresented as academic staff in engineering programs at South African universities. The problem is exacerbated at historically White institutions (HWI) where Black women are simply absent as engineering research and teaching staff. The absence of Black African women in the academy occurs despite Black African…

Conserved current for the Cotton tensor, black hole entropy and equivariant Pontryagin forms

Energy Technology Data Exchange (ETDEWEB)

Ferreiro Perez, Roberto, E-mail: roferreiro@ccee.ucm.e [Departamento de Economia Financiera y Contabilidad I Facultad de Ciencias Economicas y Empresariales, UCM Campus de Somosaguas, 28223-Pozuelo de Alarcon (Spain)

2010-07-07

The Chern-Simons Lagrangian density in the space of metrics of a three-dimensional manifold M is not invariant under the action of diffeomorphisms on M. However, its Euler-Lagrange operator can be identified with the Cotton tensor, which is invariant under diffeomorphims. As the Lagrangian is not invariant, the Noether theorem cannot be applied to obtain conserved currents. We show that it is possible to obtain an equivariant conserved current for the Cotton tensor by using the first equivariant Pontryagin form on the bundle of metrics. Finally we define a Hamiltonian current which gives the contribution of the Chern-Simons term to the black hole entropy, energy and angular momentum.

Conserved current for the Cotton tensor, black hole entropy and equivariant Pontryagin forms

International Nuclear Information System (INIS)

Ferreiro Perez, Roberto

2010-01-01

The Chern-Simons Lagrangian density in the space of metrics of a three-dimensional manifold M is not invariant under the action of diffeomorphisms on M. However, its Euler-Lagrange operator can be identified with the Cotton tensor, which is invariant under diffeomorphims. As the Lagrangian is not invariant, the Noether theorem cannot be applied to obtain conserved currents. We show that it is possible to obtain an equivariant conserved current for the Cotton tensor by using the first equivariant Pontryagin form on the bundle of metrics. Finally we define a Hamiltonian current which gives the contribution of the Chern-Simons term to the black hole entropy, energy and angular momentum.

Primary black holes

International Nuclear Information System (INIS)

Novikov, I.; Polnarev, A.

1981-01-01

Proves are searched for of the formation of the so-called primary black holes at the very origin of the universe. The black holes would weigh less than 10 13 kg. The formation of a primary black hole is conditional on strong fluctuations of the gravitational field corresponding roughly to a half of the fluctuation maximally permissible by the general relativity theory. Only big fluctuations of the gravitational field can overcome the forces of the hot gas pressure and compress the originally expanding matter into a black hole. Low-mass black holes have a temperature exceeding that of the black holes formed from stars. A quantum process of particle formation, the so-called evaporation takes place in the strong gravitational field of a black hole. The lower the mass of the black hole, the shorter the evaporation time. The analyses of processes taking place during the evaporation of low-mass primary black holes show that only a very small proportion of the total mass of the matter in the universe could turn into primary black holes. (M.D.)

The angry black woman: the impact of pejorative stereotypes on psychotherapy with black women.

Science.gov (United States)

Ashley, Wendy

2014-01-01

In the aftermath of slavery and the resulting social, economic, and political effects, Black women have become the victims of negative stereotyping in mainstream American culture. Such stereotypes include the myth of the angry Black woman that characterizes these women as aggressive, ill tempered, illogical, overbearing, hostile, and ignorant without provocation. Symptoms presented by Black women during mental health treatment may reinforce this myth. However, many of the negative characteristics of the angry Black woman developed in response to external stressors and historical factors. Black women also have a unique experience with and expressions of anger that shape the presenting symptoms interpreted by the mental health clinician. This myth and corresponding negative stereotypes significantly affect Black women intrapsychically, interpersonally, and are likely to influence the efficacy of mental health treatment. Understanding and treatment of Black women in a mental health context should be influenced by the cultural norms and sociopolitical dynamics affecting these clients. Successful mental health treatment requires cultural competence and clinicians who are well prepared to navigate the inherent complexities of culture with clients. Awareness of the angry Black woman mythology, including its genesis, manifestations, and the unique experiences of Black women, may raise the standards of cultural competence for clinicians and provide more successful treatment outcomes in working with this population. A case example illustrates the assiduity essential to practicing in a culturally competent manner. A client is presented from a traditional psychotherapeutic perspective and then viewed through a lens that integrates psychotherapeutic practice with conscious awareness of the mythology and stereotypes impacting Black women. Implications for culturally relevant practice are discussed.

Exploring the Perceptions of HBCU Student Affairs Practitioners toward the Racial Diversification of Black Colleges

Science.gov (United States)

Palmer, Robert T.; Arroyo, Andrew T.; Maramba, Dina C.

2018-01-01

While research has shown that the racial diversity of historically Black colleges and universities (HBCUs) is increasing, literature suggests that some stakeholders at HBCUs feel the diversification of Black colleges could change their culture, which some see as vital for promoting the success of Black students. Given this, the following study…

Harriet Powers: Portrait of a Black Quilter.

Science.gov (United States)

Frye, Gladys-Marie

1987-01-01

Discusses the following aspects of the life and art of Harriet Powers (born 1837), a Black quilter from Georgia: (1) subject matter of quilts; (2) African continuity; (3) provenance of quilts; (4) Powers' personal history; and (5) historical context of quilts. (BJV)

Einstein's enigma or black holes in my bubble bath

CERN Document Server

Vishveshwara, C V

2006-01-01

A funny rendition of the story of gravitation theory from the early historic origins to the developments in astrophysics, focusing on Albert Einstein''s theory of general relativity and black-hole physics.

Estimates of tsunami damage for Russian coast of the Black Sea

Science.gov (United States)

Zaytsev, Andrey; Yalciner, Ahmet; Pelinovsky, Efim

2010-05-01

The historic database of tsunamis in the Black Sea contains 20 - 30 events with different level of validity, and at least six events occurred in 20th century. Numerical modeling of the last historic events is performed in the framework of shallow-water theory with use of code NAMI-DANCE. The computed tide-gauge records in Russian coastal locations are in good agreement with instrumental data for the 1939 and 1966 tsunamis. The tsunami of the landslide origin occurred in Sochi in 1970 is modeled in the framework of the two-layer model realized in TUNAMI. Also, some hypothetic tsunamis generated in the open part of the Black Sea are computed and the distribution of the tsunami height along the Russian and Turkish coast ais found. In particular, the tsunami amplification near Sochi is highest to compare with other coastal locations on the Russian coast of Black Sea.

Black spruce growth forms as a record of a changing winter environment at treeline, Quebec, Canada

International Nuclear Information System (INIS)

Lavoie, C.; Payette, S.

1992-01-01

The environmental conditions prevailing at treeline in subarctic Quebec have been reconstructed over the past 400 yr through a comparative analysis of tree rings and growth forms of black spruce (Picea mariana [Mill.] B.S.P.). Because black spruce growth forms are closely associated with the winter environment, they are a direct response to conditions of low temperature and windblown snow abrasion affecting living tissues at the snow-air interface. The age structure of supranival shoot populations was closely associated with periods of higher stem survival in winter most likely under snowier and windless conditions. Spruce growth on slopes and in the valley revealed periods of low tree-ring growth between 1601 and 1663 and between 1700 and 1904, respectively. A long-lasting period of low radial growth 1697 and 1939 prevailed in the hilltop site. During the 20th century, spruce height increased from 0.8 to 1.6 m on slopes and in the valley, while the basal level of abrasion from windblown snow increased from 0.1 to 0.5 m, suggesting an increasing trend towards warmer and snowier conditions. Abraded spruces growing during the Little Ice Age (1570-1880) were replaced by symmetrical trees during the 20th century. Supranival skirted and whorled spruces which dominated on the hilltop site during the 16th century reverted to infranival cushion and mat growth forms during the Little Ice Age. These stunted spruces were unable to recover during the recent warming because of their inability to catch enough drifting snow to allow vertical growth

Quasar Formation and Energy Emission in Black Hole Universe

Directory of Open Access Journals (Sweden)

Zhang T. X.

2012-07-01

Full Text Available Formation and energy emission of quasars are investigated in accord with the black hole universe, a new cosmological model recently developed by Zhang. According to this new cosmological model, the universe originated from a star-like black hole and grew through a supermassive black hole to the present universe by accreting ambient matter and merging with other black holes. The origin, structure, evolution, expansion, and cosmic microwave background radiation of the black hole universe have been fully ex- plained in Paper I and II. This study as Paper III explains how a quasar forms, ignites and releases energy as an amount of that emitted by dozens of galaxies. A main sequence star, after its fuel supply runs out, will, in terms of its mass, form a dwarf, a neutron star, or a black hole. A normal galaxy, after its most stars have run out of their fuels and formed dwarfs, neutron stars, and black holes, will eventually shrink its size and collapse towards the center by gravity to form a supermassive black hole with billions of solar masses. This collapse leads to that extremely hot stellar black holes merge each other and further into the massive black hole at the center and meantime release a huge amount of radiation energy that can be as great as that of a quasar. Therefore, when the stellar black holes of a galaxy collapse and merge into a supermassive black hole, the galaxy is activated and a quasar is born. In the black hole universe, the observed dis- tant quasars powered by supermassive black holes can be understood as donuts from the mother universe. They were actually formed in the mother universe and then swallowed into our universe. The nearby galaxies are still very young and thus quiet at the present time. They will be activated and further evolve into quasars after billions of years. At that time, they will enter the universe formed by the currently observed distant quasars as similar to the distant quasars entered our universe

Black Hole Paradoxes

International Nuclear Information System (INIS)

Joshi, Pankaj S.; Narayan, Ramesh

2016-01-01

We propose here that the well-known black hole paradoxes such as the information loss and teleological nature of the event horizon are restricted to a particular idealized case, which is the homogeneous dust collapse model. In this case, the event horizon, which defines the boundary of the black hole, forms initially, and the singularity in the interior of the black hole at a later time. We show that, in contrast, gravitational collapse from physically more realistic initial conditions typically leads to the scenario in which the event horizon and space-time singularity form simultaneously. We point out that this apparently simple modification can mitigate the causality and teleological paradoxes, and also lends support to two recently suggested solutions to the information paradox, namely, the ‘firewall’ and ‘classical chaos’ proposals. (paper)

Caged black holes: Black holes in compactified spacetimes. I. Theory

International Nuclear Information System (INIS)

Kol, Barak; Sorkin, Evgeny; Piran, Tsvi

2004-01-01

In backgrounds with compact dimensions there may exist several phases of black objects including a black hole and a black string. The phase transition between them raises questions and touches on fundamental issues such as topology change, uniqueness, and cosmic censorship. No analytic solution is known for the black hole, and moreover one can expect approximate solutions only for very small black holes, while phase transition physics happens when the black hole is large. Hence we turn to numerical solutions. Here some theoretical background to the numerical analysis is given, while the results will appear in a subsequent paper. The goals for a numerical analysis are set. The scalar charge and tension along the compact dimension are defined and used as improved order parameters which put both the black hole and the black string at finite values on the phase diagram. The predictions for small black holes are presented. The differential and the integrated forms of the first law are derived, and the latter (Smarr's formula) can be used to estimate the 'overall numerical error'. Field asymptotics and expressions for physical quantities in terms of the numerical values are supplied. The techniques include the 'method of equivalent charges', free energy, dimensional reduction, and analytic perturbation for small black holes

The Relationship between Identity-Related Constructs and Positive Mental Health in Black College Students

Science.gov (United States)

Mushonga, Dawnsha R.

2017-01-01

This cross-sectional, exploratory study examined positive mental health (PMH) in 156 Black college students, ages 18-25, attending Historically Black Colleges and Universities (HBCUs) and Predominantly White Institutions (PWIs). In addition, identity-related constructs such as spirituality, self-esteem, social support, life satisfaction, racial…

Morphometric variation among spawning cisco aggregations in the Laurentian Great Lakes: are historic forms still present?

Science.gov (United States)

Yule, Daniel L.; Moore, Seth A.; Ebener, Mark P.; Claramunt, Randall M.; Pratt, Thomas C.; Salawater, Lorrie L.; Connerton, Michael J.

2013-01-01

Cisco (Coregonus artedi Leseur, formerly lake herring Leucichthys artedi Leseur) populations in each of the Laurentian Great Lakes collapsed between the late 1920s and early 1960s following a multitude of stressors, and never recovered in Lakes Michigan, Erie and Ontario. Prior to their collapse, Koelz (1929) studied Leucichthys spp. in the Great Lakes basin and provided a description of their diversity. Three cisco morphotypes were described; a ‘slim terete’morphotype (L. artedi artedi), a ‘deep compressed’ morphotype (L. artedi albus), and a deep-bodied form resembling tullibee in western Canadian lakes (L. artedi manitoulinus). Based on body measurements of 159 individuals (Koelz 1929), we used discriminant function analysis (DFA) to discriminate historic morphotypes. Shapes of historic morphotypes were found to vary significantly (Pillai’s trace = 1.16, P cisco. Important discriminating measurements included body depth, eye diameter, and dorsal fin base and height. Between October-November of 2007-2011, we sampled cisco from 16 Great Lakes sites collecting digital photographs of over 1, 700 individuals. We applied the DFA model to their body measurements and classified each individual to a morphotype. Contemporary cisco from Lakes Superior, Ontario and Michigan were predominantly classified as artedi, while the most common classifications from northern Lake Huron were albus and manitoulinus. Finding historic morphotypes is encouraging because it suggests that the morphological variation present prior to their collapse still exists. We conclude that contemporary cisco having shapes matching the missing historic morphotypes in the lower lakes warrant special consideration as potential donor populations in reestablishment efforts.

An HBCU-Based Educational Approach for Black College Student Success: Toward a Framework with Implications for All Institutions

Science.gov (United States)

Arroyo, Andrew T.; Gasman, Marybeth

2014-01-01

This conceptual study builds an institution-focused, non-Eurocentric, theoretical framework of black college student success. Specifically, the study synthesizes the relevant empirical research on the contributions historically black colleges and universities (HBCUs) have made for black student success, leading to an original model that all…

Revolutionary Black Culture: The Cultural Arm of Revolutionary Nationalism

Science.gov (United States)

Mkalimoto, Ernie

1969-01-01

Emphasizes that armed might is not the only form, nor the only necessary form of struggle in Black revolutionary nationalism; that Black poets, actors, writers, and artists, as well as political and military cadres, must unite with the Black masses in one common effort. (RJ)

Forging a Black identity

Directory of Open Access Journals (Sweden)

Barry Chevannes

1992-07-01

Full Text Available [First paragraph] The Rastafarians: sounds of cultural dissonance [revised and updated editionj. LEONARD E. BARRETT, SR. Boston: Beacon Press, 1988. xviii + 302 pp. (Paper US$ 11.95 Rasta and resistance: from Marcus Garvey to Walter Rodney. HORACE CAMPBELL. Trenton NJ: Africa World Press, 1987. xiii + 236 pp. (Cloth US$32.95, Paper US$ 10.95 Garvey's children: the legacy of Marcus Garvey. TONY SEWELL. London: Macmillan Caribbean, 1990. 128 pp. (Paper £ 17.95 The central theme linking these three titles is the evolution of a black identity among English-speaking Caribbean peoples, in particular Jamaicans. Consequently all three authors cover the two most important historical phenomena in Caribbean black nationalism, namely Garveyism and Rastafari, one focusing on the former and the other two focusing on the latter.

Cross-Cultural Peer Mentoring: One Approach to Enhancing White Faculty Adjustment at Black Colleges

Science.gov (United States)

Louis, Dave A.

2015-01-01

White faculty members at Black colleges in the United States face numerous social obstacles. Exploring the experiences of White faculty members at four historically Black colleges and universities (HBCUs) and their adjustment to a minority status assists the comprehension of issues surrounding this subgroup. Utilizing a phenomenological approach,…

Surprise: Dwarf Galaxy Harbors Supermassive Black Hole

Science.gov (United States)

2011-01-01

The surprising discovery of a supermassive black hole in a small nearby galaxy has given astronomers a tantalizing look at how black holes and galaxies may have grown in the early history of the Universe. Finding a black hole a million times more massive than the Sun in a star-forming dwarf galaxy is a strong indication that supermassive black holes formed before the buildup of galaxies, the astronomers said. The galaxy, called Henize 2-10, 30 million light-years from Earth, has been studied for years, and is forming stars very rapidly. Irregularly shaped and about 3,000 light-years across (compared to 100,000 for our own Milky Way), it resembles what scientists think were some of the first galaxies to form in the early Universe. "This galaxy gives us important clues about a very early phase of galaxy evolution that has not been observed before," said Amy Reines, a Ph.D. candidate at the University of Virginia. Supermassive black holes lie at the cores of all "full-sized" galaxies. In the nearby Universe, there is a direct relationship -- a constant ratio -- between the masses of the black holes and that of the central "bulges" of the galaxies, leading them to conclude that the black holes and bulges affected each others' growth. Two years ago, an international team of astronomers found that black holes in young galaxies in the early Universe were more massive than this ratio would indicate. This, they said, was strong evidence that black holes developed before their surrounding galaxies. "Now, we have found a dwarf galaxy with no bulge at all, yet it has a supermassive black hole. This greatly strengthens the case for the black holes developing first, before the galaxy's bulge is formed," Reines said. Reines, along with Gregory Sivakoff and Kelsey Johnson of the University of Virginia and the National Radio Astronomy Observatory (NRAO), and Crystal Brogan of the NRAO, observed Henize 2-10 with the National Science Foundation's Very Large Array radio telescope and

Segregation or "Thinking Black"?: Community Activism and the Development Of Black-Focused Schools in Toronto and London, 1968-2008

Science.gov (United States)

Johnson, Lauri

2013-01-01

Background/Context: On January 29, 2008 the Toronto District School Board (TDSB) approved a city-wide Africentric elementary school under their Alternative School policy, sparking a contentious debate. Calls for Black-focused schools also arose in 2008 in London in response to the disengagement of African Caribbean youth. The historical record…

Review of black-tailed prairie dog reintroduction strategies and site selection: Arizona reintroduction

Science.gov (United States)

Sarah L. Hale; John L. Koprowski; Holly Hicks

2013-01-01

The black-tailed prairie dog (Cynomys ludovicianus) was once widely distributed throughout the western United States; however, anthropogenic influences have reduced the species’ numbers to 2 percent of historical populations. Black-tailed prairie dogs are described as a keystone species in the grassland ecosystem, and provide many unique services, including burrows for...

Black Lives Matter: A Call to Action for Counseling Psychology Leaders.

Science.gov (United States)

Crowell, Candice; Mosley, Della; Falconer, Jameca; Faloughi, Reuben; Singh, Anneliese; Stevens-Watkins, Danelle; Cokley, Kevin

2017-08-01

Police brutality and widespread systemic racism represent historical and current sources of trauma in Black communities. Both the Black Lives Matter movement and counseling psychology propose to confront these realities at multiple levels. Black Lives Matter seeks to increase awareness about systemic racism and promote resilience among Black people. Counseling psychology states values of multiculturalism, social justice, and advocacy. Executive leadership in counseling psychology may seek to promote racial justice, yet struggle with how to participate in Black Lives Matter movements and address racial discrimination within larger systems spontaneously and consistently. However, counseling psychology trainees and professionals are actively involved in the Black Lives Matter movement, leading the way forward. Through the framework of spontaneity in social movements, this manuscript highlights what counseling psychologists are currently contributing to Black Lives Matter and makes recommendations that build on the opportunity counseling psychologists have for further involvement in the movement.

Statistical clustering of primordial black holes

Energy Technology Data Exchange (ETDEWEB)

Carr, B J [Cambridge Univ. (UK). Inst. of Astronomy

1977-04-01

It is shown that Meszaros theory of galaxy formation, in which galaxies form from the density perturbations associated with the statistical fluctuation in the number density of primordial black holes, must be modified if the black holes are initially surrounded by regions of lower radiation density than average (as is most likely). However, even in this situation, the sort of effect Meszaros envisages does occur and could in principle cause galactic mass-scales to bind at the conventional time. In fact, the requirement that galaxies should not form prematurely implies that black holes could not have a critical density in the mass range above 10/sup 5/ M(sun). If the mass spectrum of primordial black holes falls off more slowly than m/sup -3/ (as expected), then the biggest black holes have the largest clustering effect. In this case the black hole clustering theory of galaxy formation reduces to the black hole seed theory of galaxy formation, in which each galaxy becomes bound under the gravitational influence of a single black hole nucleus. The seed theory could be viable only if the early Universe had a soft equation of state until a time exceeding 10/sup -4/ s or if something prevented black hole formation before 1 s.

Repackaging SRS Black Box TRU Waste

International Nuclear Information System (INIS)

Swale, D. J.; Stone, K.A.; Milner, T. N.

2006-01-01

Historically, large items of TRU Waste, which were too large to be packaged in drums for disposal have been packaged in various sizes of custom made plywood boxes at the Savannah River Site (SRS), for many years. These boxes were subsequently packaged into large steel ''Black Boxes'' for storage at SRS, pending availability of Characterization and Certification capability, to facilitate disposal of larger items of TRU Waste. There are approximately 107 Black Boxes in inventory at SRS, each measuring some 18' x 12' x 7', and weighing up to 45,000 lbs. These Black Boxes have been stored since the early 1980s. The project to repackage this waste into Standard Large Boxes (SLBs), Standard Waste Boxes (SWB) and Ten Drum Overpacks (TDOP), for subsequent characterization and WIPP disposal, commenced in FY04. To date, 10 Black Boxes have been repackaged, resulting in 40 SLB-2's, and 37 B25 overpack boxes, these B25's will be overpacked in SLB-2's prior to shipping to WIPP. This paper will describe experience to date from this project

The Tuskegee Syphilis Study, 1932 to 1972: implications for HIV education and AIDS risk education programs in the black community.

Science.gov (United States)

Thomas, S B; Quinn, S C

1991-01-01

The Tuskegee study of untreated syphilis in the Negro male is the longest nontherapeutic experiment on human beings in medical history. The strategies used to recruit and retain participants were quite similar to those being advocated for HIV/AIDS prevention programs today. Almost 60 years after the study began, there remains a trail of distrust and suspicion that hampers HIV education efforts in Black communities. The AIDS epidemic has exposed the Tuskegee study as a historical marker for the legitimate discontent of Blacks with the public health system. The belief that AIDS is a form of genocide is rooted in a social context in which Black Americans, faced with persistent inequality, believe in conspiracy theories about Whites against Blacks. These theories range from the belief that the government promotes drug abuse in Black communities to the belief that HIV is a manmade weapon of racial warfare. An open and honest discussion of the Tuskegee Syphilis Study can facilitate the process of rebuilding trust between the Black community and public health authorities. This dialogue can contribute to the development of HIV education programs that are scientifically sound, culturally sensitive, and ethnically acceptable. Images p1500-a p1502-a p1503-a PMID:1951814

A New Model of Black Hole Formation

Directory of Open Access Journals (Sweden)

Thayer G. D.

2013-10-01

Full Text Available The formation of a black hole and its event horizon are described. Conclusions, which are the result of a thought experiment, show that Schwarzschild [1] was correct: A singularity develops at the event horizon of a newly-formed black hole. The intense gravitational field that forms near the event horizon results in the mass-energy of the black hole accumulating in a layer just inside the event horizon, rather than collapsing into a central singularity.

The Black Swan and the owl of Minerva: Nassim Nicholas Taleb and the historians

OpenAIRE

Bennett, Bruce S.

2014-01-01

In The Black Swan, Nassim Nicholas Taleb considers the importance in human affairs of "Black Swan" events of low probability but high impact. In the process he argues, in a confrontational manner, that historians' causal narratives are mainly invalid on a number of grounds but especially because the unpredictability of Black Swan (or other) events implies that subsequent narratives connecting events are merely "good-sounding stories". This article analyses Taleb's arguments against historical...

Magnetohydrodynamics near a black hole

International Nuclear Information System (INIS)

Wilson, J.R.

1975-01-01

A numerical computer study of hydromagnetic flow near a black hole is presented. First, the equations of motion are developed to a form suitable for numerical computations. Second, the results of calculations describing the magnetic torques exerted by a rotating black hole on a surrounding magnetic plasma and the electric charge that is induced on the surface of the black hole are presented. (auth)

Black Americans, Africa and History: A Reassessment of the Pan-African and Identity Paradigms.

Science.gov (United States)

Adeleke, Tunde

1998-01-01

Examines the paradigm of Pan-Africanism and the identity construct in the historic and cultural contexts of blacks outside of Africa, critiquing theories on the African identity construct. Suggests that black American identity is too complex for this simplification and must be considered within the context of world acculturation. Contains 34…

Relationships, Being-ness, and Voice: Exploring Multiple Dimensions of Humanizing Work with Black Girls

Science.gov (United States)

Edwards, Erica; McArthur, Sherell A.; Russell-Owens, LaToya

2016-01-01

This work argues for an approach to research and education practices that considers the historically deficit-based research practices and views on Black girls and develops humanizing research methods that consider the multiple oppressions that act as barriers for this group. Research must acknowledge the precarious position of Black girls in order…

From "brute" to "thug:" the demonization and criminalization of unarmed Black male victims in America.

Science.gov (United States)

Smiley, CalvinJohn; Fakunle, David

The synonymy of Blackness with criminality is not a new phenomenon in America. Documented historical accounts have shown how myths, stereotypes, and racist ideologies led to discriminatory policies and court rulings that fueled racial violence in a post-Reconstruction era and has culminated in the exponential increase of Black male incarceration today. Misconceptions and prejudices manufactured and disseminated through various channels such as the media included references to a " brute " image of Black males. In the 21 st century, this negative imagery of Black males has frequently utilized the negative connotation of the terminology " thug ." In recent years, law enforcement agencies have unreasonably used deadly force on Black males allegedly considered to be "suspects" or "persons of interest." The exploitation of these often-targeted victims' criminal records, physical appearances, or misperceived attributes has been used to justify their unlawful deaths. Despite the connection between disproportionate criminality and Black masculinity, little research has been done on how unarmed Black male victims, particularly but not exclusively at the hands of law enforcement, have been posthumously criminalized. This paper investigates the historical criminalization of Black males and its connection to contemporary unarmed victims of law enforcement. Action research methodology in the data collection process is utilized to interpret how Black male victims are portrayed by traditional mass media, particularly through the use of language, in ways that marginalize and de-victimize these individuals. This study also aims to elucidate a contemporary understanding of race relations, racism, and the plight of the Black male in a 21-century "post-racial" America.

Cosmology with primordial black holes

International Nuclear Information System (INIS)

Lindley, D.

1981-09-01

Cosmologies containing a substantial amount of matter in the form of evaporating primordial black holes are investigated. A review of constraints on the numbers of such black holes, including an analysis of a new limit found by looking at the destruction of deuterium by high energy photons, shows that there must be a negligible population of small black holes from the era of cosmological nucleosynthesis onwards, but that there are no strong constraints before this time. The major part of the work is based on the construction of detailed, self-consistent cosmological models in which black holes are continually forming and evaporating The interest in these models centres on the question of baryon generation, which occurs via the asymmetric decay of a new type of particle which appears as a consequence of the recently developed Grand Unified Theories of elementary particles. Unfortunately, there is so much uncertainty in the models that firm conclusions are difficult to reach; however, it seems feasible in principle that primordial black holes could be responsible for a significant part of the present matter density of the Universe. (author)

Black holes and the multiverse

International Nuclear Information System (INIS)

Garriga, Jaume; Vilenkin, Alexander; Zhang, Jun

2016-01-01

Vacuum bubbles may nucleate and expand during the inflationary epoch in the early universe. After inflation ends, the bubbles quickly dissipate their kinetic energy; they come to rest with respect to the Hubble flow and eventually form black holes. The fate of the bubble itself depends on the resulting black hole mass. If the mass is smaller than a certain critical value, the bubble collapses to a singularity. Otherwise, the bubble interior inflates, forming a baby universe, which is connected to the exterior FRW region by a wormhole. A similar black hole formation mechanism operates for spherical domain walls nucleating during inflation. As an illustrative example, we studied the black hole mass spectrum in the domain wall scenario, assuming that domain walls interact with matter only gravitationally. Our results indicate that, depending on the model parameters, black holes produced in this scenario can have significant astrophysical effects and can even serve as dark matter or as seeds for supermassive black holes. The mechanism of black hole formation described in this paper is very generic and has important implications for the global structure of the universe. Baby universes inside super-critical black holes inflate eternally and nucleate bubbles of all vacua allowed by the underlying particle physics. The resulting multiverse has a very non-trivial spacetime structure, with a multitude of eternally inflating regions connected by wormholes. If a black hole population with the predicted mass spectrum is discovered, it could be regarded as evidence for inflation and for the existence of a multiverse

Black holes and the multiverse

Energy Technology Data Exchange (ETDEWEB)

Garriga, Jaume [Departament de Fisica Fonamental i Institut de Ciencies del Cosmos, Universitat de Barcelona, Marti i Franques, 1, Barcelona, 08028 Spain (Spain); Vilenkin, Alexander; Zhang, Jun, E-mail: jaume.garriga@ub.edu, E-mail: vilenkin@cosmos.phy.tufts.edu, E-mail: jun.zhang@tufts.edu [Institute of Cosmology, Tufts University, 574 Boston Ave, Medford, MA, 02155 (United States)

2016-02-01

Vacuum bubbles may nucleate and expand during the inflationary epoch in the early universe. After inflation ends, the bubbles quickly dissipate their kinetic energy; they come to rest with respect to the Hubble flow and eventually form black holes. The fate of the bubble itself depends on the resulting black hole mass. If the mass is smaller than a certain critical value, the bubble collapses to a singularity. Otherwise, the bubble interior inflates, forming a baby universe, which is connected to the exterior FRW region by a wormhole. A similar black hole formation mechanism operates for spherical domain walls nucleating during inflation. As an illustrative example, we studied the black hole mass spectrum in the domain wall scenario, assuming that domain walls interact with matter only gravitationally. Our results indicate that, depending on the model parameters, black holes produced in this scenario can have significant astrophysical effects and can even serve as dark matter or as seeds for supermassive black holes. The mechanism of black hole formation described in this paper is very generic and has important implications for the global structure of the universe. Baby universes inside super-critical black holes inflate eternally and nucleate bubbles of all vacua allowed by the underlying particle physics. The resulting multiverse has a very non-trivial spacetime structure, with a multitude of eternally inflating regions connected by wormholes. If a black hole population with the predicted mass spectrum is discovered, it could be regarded as evidence for inflation and for the existence of a multiverse.

Slowly balding black holes

International Nuclear Information System (INIS)

Lyutikov, Maxim; McKinney, Jonathan C.

2011-01-01

The 'no-hair' theorem, a key result in general relativity, states that an isolated black hole is defined by only three parameters: mass, angular momentum, and electric charge; this asymptotic state is reached on a light-crossing time scale. We find that the no-hair theorem is not formally applicable for black holes formed from the collapse of a rotating neutron star. Rotating neutron stars can self-produce particles via vacuum breakdown forming a highly conducting plasma magnetosphere such that magnetic field lines are effectively ''frozen in'' the star both before and during collapse. In the limit of no resistivity, this introduces a topological constraint which prohibits the magnetic field from sliding off the newly-formed event horizon. As a result, during collapse of a neutron star into a black hole, the latter conserves the number of magnetic flux tubes N B =eΦ ∞ /(πc(ℎ/2π)), where Φ ∞ ≅2π 2 B NS R NS 3 /(P NS c) is the initial magnetic flux through the hemispheres of the progenitor and out to infinity. We test this theoretical result via 3-dimensional general relativistic plasma simulations of rotating black holes that start with a neutron star dipole magnetic field with no currents initially present outside the event horizon. The black hole's magnetosphere subsequently relaxes to the split-monopole magnetic field geometry with self-generated currents outside the event horizon. The dissipation of the resulting equatorial current sheet leads to a slow loss of the anchored flux tubes, a process that balds the black hole on long resistive time scales rather than the short light-crossing time scales expected from the vacuum no-hair theorem.

ULTRAMASSIVE BLACK HOLE COALESCENCE

International Nuclear Information System (INIS)

Khan, Fazeel Mahmood; Holley-Bockelmann, Kelly; Berczik, Peter

2015-01-01

Although supermassive black holes (SMBHs) correlate well with their host galaxies, there is an emerging view that outliers exist. Henize 2-10, NGC 4889, and NGC 1277 are examples of SMBHs at least an order of magnitude more massive than their host galaxy suggests. The dynamical effects of such ultramassive central black holes is unclear. Here, we perform direct N-body simulations of mergers of galactic nuclei where one black hole is ultramassive to study the evolution of the remnant and the black hole dynamics in this extreme regime. We find that the merger remnant is axisymmetric near the center, while near the large SMBH influence radius, the galaxy is triaxial. The SMBH separation shrinks rapidly due to dynamical friction, and quickly forms a binary black hole; if we scale our model to the most massive estimate for the NGC 1277 black hole, for example, the timescale for the SMBH separation to shrink from nearly a kiloparsec to less than a parsec is roughly 10 Myr. By the time the SMBHs form a hard binary, gravitational wave emission dominates, and the black holes coalesce in a mere few Myr. Curiously, these extremely massive binaries appear to nearly bypass the three-body scattering evolutionary phase. Our study suggests that in this extreme case, SMBH coalescence is governed by dynamical friction followed nearly directly by gravitational wave emission, resulting in a rapid and efficient SMBH coalescence timescale. We discuss the implications for gravitational wave event rates and hypervelocity star production

Black holes new horizons

CERN Document Server

Hayward, Sean Alan

2013-01-01

Black holes, once just fascinating theoretical predictions of how gravity warps space-time according to Einstein's theory, are now generally accepted as astrophysical realities, formed by post-supernova collapse, or as supermassive black holes mysteriously found at the cores of most galaxies, powering active galactic nuclei, the most powerful objects in the universe. Theoretical understanding has progressed in recent decades with a wider realization that local concepts should characterize black holes, rather than the global concepts found in textbooks. In particular, notions such as trapping h

Investing in Diversity in London Schools: Leadership Preparation for Black and Global Majority Educators

Science.gov (United States)

Johnson, Lauri; Campbell-Stephens, Rosemary

2010-01-01

This article traces the historical roots, describes the philosophy and curriculum, and analyzes the approach to leadership in Investing in Diversity, a 1-year Black-led leadership development course in the London schools. An exploratory qualitative case study approach was used to collect historical and empirical data about the program over a…

'Black Athena' and Africa's contribution to global cultural history

NARCIS (Netherlands)

Binsbergen, van W.M.J.

1996-01-01

Martin Bernal's 'Black Athena' has evoked three kinds of reaction: scholarly evaluation of the historical evidence for Bernal's claims, both of Ancient Europe's indebtedness to West Asia and Northeast Africa, and of the construction in recent centuries of the Greek miracle as a Eurocentric,

Relativistic hydrodynamic evolutions with black hole excision

International Nuclear Information System (INIS)

Duez, Matthew D.; Shapiro, Stuart L.; Yo, H.-J.

2004-01-01

We present a numerical code designed to study astrophysical phenomena involving dynamical spacetimes containing black holes in the presence of relativistic hydrodynamic matter. We present evolutions of the collapse of a fluid star from the onset of collapse to the settling of the resulting black hole to a final stationary state. In order to evolve stably after the black hole forms, we excise a region inside the hole before a singularity is encountered. This excision region is introduced after the appearance of an apparent horizon, but while a significant amount of matter remains outside the hole. We test our code by evolving accurately a vacuum Schwarzschild black hole, a relativistic Bondi accretion flow onto a black hole, Oppenheimer-Snyder dust collapse, and the collapse of nonrotating and rotating stars. These systems are tracked reliably for hundreds of M following excision, where M is the mass of the black hole. We perform these tests both in axisymmetry and in full 3+1 dimensions. We then apply our code to study the effect of the stellar spin parameter J/M 2 on the final outcome of gravitational collapse of rapidly rotating n=1 polytropes. We find that a black hole forms only if J/M 2 2 >1, the collapsing star forms a torus which fragments into nonaxisymmetric clumps, capable of generating appreciable 'splash' gravitational radiation

Research, Ideology, and the Brown Decision: Counter-Narratives to the Historical and Contemporary Representation of Black Schooling

Science.gov (United States)

Morris, Jerome

2008-01-01

Background/Context: Most narratives of Brown v. Board of Education primarily focus on integrated schooling as the ultimate objective in Black people's quest for quality schooling. Rather than uniformly assuming integration as Black people's ideological model, the push by Black people for quality schooling instead should be viewed within the…

Black holes a very short introduction

CERN Document Server

Blundell, Katherine

2015-01-01

Black holes are a constant source of fascination to many due to their mysterious nature. Black Holes: A Very Short Introduction addresses a variety of questions, including what a black hole actually is, how they are characterized and discovered, and what would happen if you came too close to one. It explains how black holes form and grow—by stealing material that belongs to stars—as well as how many there may be in the Universe. It also explores the large black holes found in the centres of galaxies, and how black holes power quasars and lie behind other spectacular phenomena in the cosmos.

Partnership Opportunities In Earth System Science Education Between Historically Black and Historically White Universities: Elizabeth City State University and the University of New Hampshire

Science.gov (United States)

Williams, J. E.; Hayden, L. B.; Wake, C. P.; Varner, R. K.; Graham, K.; Rock, B. N.; Hale, S.; Hurtt, G. C.; Porter, W.; Blackmon, R.; Bryce, J. G.; Branch, B. D.; Johnson, J. E.

2009-12-01

Federal efforts to promote the participation of underrepresented students in the science, technology, engineering and mathematics disciplines (STEM) in higher education have been in effect over several decades. The Science and Engineering Equal Opportunities Act of 1980 aimed to create equal opportunity in the STEM disciplines by promoting and broadening the participation of underrepresented talent in science and engineering. Since that time, federal agencies such as the National Science Foundation, NOAA and NASA, scientific organizations such as the American Geophysical Union, and other organizations such as the Educational Testing Service have created programs, diversity plans and cutting edge reports designed to further explicate the need to broaden the participation of underrepresented student talent in these disciplines. Despite increases in the degrees awarded to underrepresented students in the STEM disciplines, enhancing diversity in these disciplines continues to remain a significant challenge. This paper describes a strategic approach to this challenge via the development of a collaborative partnership model between two universities: the historically black Elizabeth City State University (ESCU) and the historically white University of New Hampshire (UNH). The alliance, built on a mutually-agreed upon set of partnership principles, strives to enhance opportunities for underrepresented students to pursue careers in STEM disciplines, specifically those in Earth system science and remote sensing. In examining the partnership, six promising practices that help advance its success come to the forefront. These practices include institutional commitment and faculty engagement, mutual respect and shared time commitment, identifying engaged leadership, engaging critical change agents, initiating difficult dialogues, and preparing for growth and evolution. Outcomes of the partnership to date include the successful submission and funding of four collaborative

The statistical clustering of primordial black holes

International Nuclear Information System (INIS)

Carr, B.J.

1977-01-01

It is shown that Meszaros theory of galaxy formation, in which galaxies form from the density perturbations associated with the statistical fluctuation in the number density of primordial black holes, must be modified if the black holes are initially surrounded by regions of lower radiation density than average (as is most likely). However, even in this situation, the sort of effect Meszaros envisages does occur and could in principle cause galactic mass-scales to bind at the conventional time. In fact, the requirement that galaxies should not form prematurely implies that black holes could not have a critical density in the mass range above 10 5 M(sun). If the mass spectrum of primordial black holes falls off more slowly than m -3 (as expected), then the biggest black holes have the largest clustering effect. In this case the black hole clustering theory of galaxy formation reduces to the black hole seed theory of galaxy formation, in which each galaxy becomes bound under the gravitational influence of a single black hole nucleus. The seed theory could be viable only if the early Universe had a soft equation of state until a time exceeding 10 -4 s or if something prevented black hole formation before 1 s. (orig.) [de

The Weak Gravity Conjecture and the axionic black hole paradox

Science.gov (United States)

Hebecker, Arthur; Soler, Pablo

2017-09-01

In theories with a perturbatively massless 2-form (dual to an axion), a paradox may arise in the process of black hole evaporation. Schwarzschild black holes can support a non-trivial Wilson-line-type field, the integral of the 2-form around their horizon. After such an `axionic black hole' evaporates, the Wilson line must be supported by the corresponding 3-form field strength in the region formerly occupied by the black hole. In the limit of small axion decay-constant f, the energy required for this field configuration is too large. Thus, energy cannot be conserved in the process of black hole evaporation. The natural resolution of this paradox is through the presence of light strings, which allow the black hole to "shed" its axionic hair sufficiently early. This gives rise to a new Weak-Gravity-type argument in the 2-form context: small coupling, in this case f , enforces the presence of light strings or a low cutoff. We also discuss how this argument may be modified in situations where the weak coupling regime is achieved in the low-energy effective theory through an appropriate gauging of a model with a vector field and two 2-forms.

Historical and projected carbon balance of mature black spruce ecosystems across north america: The role of carbon-nitrogen interactions

Science.gov (United States)

Clein, Joy S.; McGuire, A.D.; Zhang, X.; Kicklighter, D.W.; Melillo, J.M.; Wofsy, S.C.; Jarvis, P.G.; Massheder, J.M.

2002-01-01

simulated NEP (R2 = 0.36, 0.20 for coupled and uncoupled simulations, respectively) was similar to the correlations at the northern site. To evaluate the role of N dynamics in C balance of black spruce ecosystems across North America, we simulated historical and projected C dynamics from 1900 to 2100 with a global-based climatology at 0.5?? resolution (latitude ?? longitude) with both the coupled and uncoupled parameterizations of TEM. From analyses at the northern site, several consistent patterns emerge. There was greater inter-annual variability in net primary production (NPP) simulated by the uncoupled parameterization as compared to the coupled parameterization, which led to substantial differences in inter-annual variability in NEP between the parameterizations. The divergence between NPP and heterotrophic respiration was greater in the uncoupled simulation, resulting in more C sequestration during the projected period. These responses were the result of fundamentally different responses of the coupled and uncoupled parameterizations to changes in CO2 and climate. Across North American black spruce ecosystems, the range of simulated decadal changes in C storage was substantially greater for the uncoupled parameterization than for the coupled parameterization. Analysis of the spatial variability in decadal responses of C dynamics revealed that C fluxes simulated by the coupled and uncoupled parameterizations have different sensitivities to climate and that the climate sensitivities of the fluxes change over the temporal scope of the simulations. The results of this study suggest that uncertainties can be reduced through (1) factorial studies focused on elucidating the role of C and N interactions in the response of mature black spruce ecosystems to manipulations of atmospheric CO2 and climate, (2) establishment of a network of continuous, long-term measurements of C dynamics across the range of mature black spruce ecosystems in North America, and (3) ancillary

Identité et marchandisation : Le cas des black memorabilia et black collectibles Identity and Commodification: The Case of Black Memorabilia and Black Collectibles

Directory of Open Access Journals (Sweden)

Eliane Elmaleh

2009-07-01

Full Text Available The aim of this article is to raise the issue of the commodification of African American culture, mainly through a certain form of art that has re-emerged with Black memorabilia which paradoxically fit into a black-driven market. However, these items penetrated American culture from 1920 to the 1950s to convey images of black people as lazy, stupid, childlike and happy. This condition of permanent happiness, typified by a broad smile and white teeth, was a fundamental component of this racist and stereotyped imagery. Thus, this article focuses on the thin border between racism and the denunciation of racism, commodification and denunciation of commodification, art and its by-products being always co-opted in the specific logic of private productivity.

Liberation Through Education: Teaching #BlackLivesMatter in Africana Studies

OpenAIRE

Danielle M. Wallace

2016-01-01

This paper is based on teaching about #BlackLivesMatter in Africana Studies in two seminar courses during the Spring of 2015 and 2016, respectively. Guided by a pedagogy grounded in the belief that education can be a tool of social justice, arguments are made for how to frame discussions of #BlackLivesMatter in regard to the socio-historical circumstances that inform and shape the modern day movement. In addition, suggestions are made for including a discussion of the tradition of activism wi...

Tachyon hair on two-dimensional black holes

International Nuclear Information System (INIS)

Peet, A.; Susskind, L.; Thorlacius, L.

1993-01-01

Static black holes in two-dimensional string theory can carry tachyon hair. Configurations which are nonsingular at the event horizon have a nonvanishing asymptotic energy density. Such solutions can be smoothly extended through the event horizon and have a nonvanishing energy flux emerging from the past singularity. Dynamical processes will not change the amount of tachyon hair on a black hole. In particular, there will be no tachyon hair on a black hole formed in gravitational collapse if the initial geometry is the linear dilaton vacuum. There also exist static solutions with a finite total energy, which have singular event horizons. Simple dynamical arguments suggest that black holes formed in gravitational collapse will not have tachyon hair of this type

Energy level diagrams for black hole orbits

Science.gov (United States)

Levin, Janna

2009-12-01

A spinning black hole with a much smaller black hole companion forms a fundamental gravitational system, like a colossal classical analog to an atom. In an appealing if imperfect analogy with atomic physics, this gravitational atom can be understood through a discrete spectrum of periodic orbits. Exploiting a correspondence between the set of periodic orbits and the set of rational numbers, we are able to construct periodic tables of orbits and energy level diagrams of the accessible states around black holes. We also present a closed-form expression for the rational q, thereby quantifying zoom-whirl behavior in terms of spin, energy and angular momentum. The black hole atom is not just a theoretical construct, but corresponds to extant astrophysical systems detectable by future gravitational wave observatories.

Energy level diagrams for black hole orbits

International Nuclear Information System (INIS)

Levin, Janna

2009-01-01

A spinning black hole with a much smaller black hole companion forms a fundamental gravitational system, like a colossal classical analog to an atom. In an appealing if imperfect analogy with atomic physics, this gravitational atom can be understood through a discrete spectrum of periodic orbits. Exploiting a correspondence between the set of periodic orbits and the set of rational numbers, we are able to construct periodic tables of orbits and energy level diagrams of the accessible states around black holes. We also present a closed-form expression for the rational q, thereby quantifying zoom-whirl behavior in terms of spin, energy and angular momentum. The black hole atom is not just a theoretical construct, but corresponds to extant astrophysical systems detectable by future gravitational wave observatories.

On Quantum Contributions to Black Hole Growth

NARCIS (Netherlands)

Spaans, M.

2013-01-01

The effects of Wheeler’s quantum foam on black hole growth are explored from an astrophysical per- spective. Quantum fluctuations in the form of mini (10−5 g) black holes can couple to macroscopic black holes and allow the latter to grow exponentially in mass on a time scale of 109 years.

Black and white holes

International Nuclear Information System (INIS)

Zeldovich, Ya.; Novikov, I.; Starobinskij, A.

1978-01-01

The theory is explained of the origination of white holes as a dual phenomenon with regard to the formation of black holes. Theoretically it is possible to derive the white hole by changing the sign of time in solving the general theory of relativity equation implying the black hole. The white hole represents the amount of particles formed in the vicinity of a singularity. For a distant observer, matter composed of these particles expands and the outer boundaries of this matter approach from the inside the gravitational radius Rsub(r). At t>>Rsub(r)/c all radiation or expulsion of matter terminates. For the outside observer the white hole exists for an unlimited length of time. In fact, however, it acquires the properties of a black hole and all processes in it cease. The qualitative difference between a white hole and a black hole is in that a white hole is formed as the result of an inner quantum explosion from the singularity to the gravitational radius and not as the result of a gravitational collapse, i.e., the shrinkage of diluted matter towards the gravitational radius. (J.B.)

Black and white holes

Energy Technology Data Exchange (ETDEWEB)

Zeldovich, Ya; Novikov, I; Starobinskii, A

1978-07-01

The theory is explained of the origination of white holes as a dual phenomenon with regard to the formation of black holes. Theoretically it is possible to derive the white hole by changing the sign of time in solving the general theory of relativity equation implying the black hole. The white hole represents the amount of particles formed in the vicinity of a singularity. For a distant observer, matter composed of these particles expands and the outer boundaries of this matter approach from the inside the gravitational radius R/sub r/. At t>>R/sub r//c all radiation or expulsion of matter terminates. For the outside observer the white hole exists for an unlimited length of time. In fact, however, it acquires the properties of a black hole and all processes in it cease. The qualitative difference between a white hole and a black hole is in that a white hole is formed as the result of an inner quantum explosion from the singularity to the gravitational radius and not as the result of a gravitational collapse, i.e., the shrinkage of diluted matter towards the gravitational radius.

BHDD: Primordial black hole binaries code

Science.gov (United States)

Kavanagh, Bradley J.; Gaggero, Daniele; Bertone, Gianfranco

2018-06-01

BHDD (BlackHolesDarkDress) simulates primordial black hole (PBH) binaries that are clothed in dark matter (DM) halos. The software uses N-body simulations and analytical estimates to follow the evolution of PBH binaries formed in the early Universe.

Notes on Phase Transition of Nonsingular Black Hole

International Nuclear Information System (INIS)

Ma Meng-Sen; Zhao Ren

2015-01-01

On the belief that a black hole is a thermodynamic system, we study the phase transition of nonsingular black holes. If the black hole entropy takes the form of the Bekenstein—Hawking area law, the black hole mass M is no longer the internal energy of the black hole thermodynamic system. Using the thermodynamic quantities, we calculate the heat capacity, thermodynamic curvature and free energy. It is shown that there will be a larger black hole/smaller black hole phase transition for the nonsingular black hole. At the critical point, the second-order phase transition appears. (paper)

Popular Music: An Untapped Resource for Teaching Contemporary Black History.

Science.gov (United States)

Cooper, B. Lee

1979-01-01

This essay suggests two innovative instructional approaches for using popular Black music as a model for historical study in the classroom: (1) biographies of popular music artists; and (2) lyrical demonstration of social themes. A list of lyric and album resources is provided. (Author/EB)

Racial Battle Fatigue and the "Mis"Education of Black Men: Racial Microaggressions, Societal Problems, and Environmental Stress

Science.gov (United States)

Smith, William A.; Hung, Man; Franklin, Jeremy D.

2011-01-01

Black men's lives are racialized contradictions, They are told that contemporary educational and professional institutions--particularly historically White institutions (HWls)--are places where, through hard work, they can achieve the so-called American dream. However, for far too many Black men, HWIs represent racial climates that are replete…

Prissy’s Quittin’ Time: The Black Camp Aesthetics of Kara Walker

Directory of Open Access Journals (Sweden)

Stephens Brian

2017-12-01

Full Text Available Through a close reading of Walker’s first silhouette instalment-the audaciously titled Gone, An Historical Romance of a Civil War as it Occurred Between the Dusky Thighs of One Young Negress and Her Heart (1994-this article examines how Walker utilises black camp to undermine both white supremacist and restrictive black uplift discourse. To be sure, the article is not an attempt to conflate these two, for the former is powerfully worse than the latter. However, it is necessary to explore how both discourses reinforce essentialist articulations of blackness and also to examine how black camp is a provocative analytic for their simultaneous disruption. Camp is usually understood as a queer-derived cultural practice that inflates identity to expose the constructed nature of gender. However, this article shows that black articulations of camp inflate identity to demonstrate the fiction of race as well.

Black smokers and the Tree of Life

Science.gov (United States)

Linich, Michael

The molecular biology revolution has turned the classification of life on its head. Is Whittaker's five-kingdom scheme for the classification of living things no longer relevant to life science education? Coupled with this is the discovery that most microscopic life cannot yet be brought into culture. One of the key organisms making this knowledge possible is Methanococcus jannishi a microorganism found in black smokers. This workshop presents the development of the Universal Tree of Life in a historical context and then links together major concepts in the New South Wales senior science programs of Earth and Environmental Science and Biology by examining the biological and geological aspects of changes to black smokers over geological time.

Black Holes, the Brightest Objects in the Universe

Energy Technology Data Exchange (ETDEWEB)

McKinney, Jonathan (Stanford University)

2009-04-28

Black holes are everywhere in the Universe. They form when massive stars end their life in a simultaneous violent collapse and energetic explosion. Galaxies end up littered with small black holes, each roughly the mass of ten Suns. Nearly every galaxy center ends up with a single huge black hole, with the mass of a million to a billion Suns. During their lifetimes, black holes chew up their surroundings and spew out ultra-energetic beams of radiation and matter that are visible from across the Universe. In this lecture, I will discuss how black holes form, outline how we detect them, and show movies that illustrate how they work according to Einstein and state-of-the-art computer simulations. We will see that these blackest of all objects in the Universe actually shine the brightest.

A Historical Account of Physical Education in the Cape Colony and ...

African Journals Online (AJOL)

A sport-historical investigation was undertaken based on literature in dissertations, academic and non-academic journals and general publications. ... In Black schools, Drill and later PE was introduced mainly for the purposes of discipline and social control, as well as the commonly known idea of medical and health ...

Topics in black-hole physics: geometric constraints on noncollapsing, gravitating systems, and tidal distortions of a Schwarzschild black hole

International Nuclear Information System (INIS)

Redmount, I.H.

1984-01-01

This dissertation consists of two studies on the general-relativistic theory of black holes. The first work concerns the fundamental issue of black-hole formation: in it geometric constraints are sought on gravitating matter systems, in the special case of axial symmetry, which determine whether or not those systems undergo gravitational collapse to form black holes. The second project deals with mechanical behavior of a black hole: specifically, the tidal deformation of a static black hole is studied by the gravitational fields of external bodies

The Origin of Black Smock and White Collar

Science.gov (United States)

Hesapcioglu, Muhsin; Meseci Giorgetti, Filiz

2009-01-01

Although there are many empirical studies on the functions of school uniform, studies which focus on the origins of school uniform are neglected. Purpose of this study is to reveal historical origins of black smock and white collar. To achieve this purpose, a qualitative research method was adopted. As a result of the research, it was determined…

Black supernovae and black holes in non-local gravity

Energy Technology Data Exchange (ETDEWEB)

Bambi, Cosimo [Center for Field Theory and Particle Physics and Department of Physics, Fudan University,200433 Shanghai (China); Theoretical Astrophysics, Eberhard-Karls Universität Tübingen,72076 Tübingen (Germany); Malafarina, Daniele [Department of Physics, Nazarbayev University,010000 Astana (Kazakhstan); Modesto, Leonardo [Center for Field Theory and Particle Physics and Department of Physics, Fudan University,200433 Shanghai (China)

2016-04-22

In a previous paper, we studied the interior solution of a collapsing body in a non-local theory of gravity super-renormalizable at the quantum level. We found that the classical singularity is replaced by a bounce, after which the body starts expanding. A black hole, strictly speaking, never forms. The gravitational collapse does not create an event horizon but only an apparent one for a finite time. In this paper, we solve the equations of motion assuming that the exterior solution is static. With such an assumption, we are able to reconstruct the solution in the whole spacetime, namely in both the exterior and interior regions. Now the gravitational collapse creates an event horizon in a finite comoving time, but the central singularity is approached in an infinite time. We argue that these black holes should be unstable, providing a link between the scenarios with and without black holes. Indeed, we find a non catastrophic ghost-instability of the metric in the exterior region. Interestingly, under certain conditions, the lifetime of our black holes exactly scales as the Hawking evaporation time.

A hermeneutic phenomenological study of the experiences of female African American undergraduate engineering students at a predominantly White and an historically Black institution

Science.gov (United States)

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.

Black holes in the early Universe.

Science.gov (United States)

Volonteri, Marta; Bellovary, Jillian

2012-12-01

The existence of massive black holes (MBHs) was postulated in the 1960s, when the first quasars were discovered. In the late 1990s their reality was proven beyond doubt in the Milky way and a handful nearby galaxies. Since then, enormous theoretical and observational efforts have been made to understand the astrophysics of MBHs. We have discovered that some of the most massive black holes known, weighing billions of solar masses, powered luminous quasars within the first billion years of the Universe. The first MBHs must therefore have formed around the time the first stars and galaxies formed. Dynamical evidence also indicates that black holes with masses of millions to billions of solar masses ordinarily dwell in the centers of today's galaxies. MBHs populate galaxy centers today, and shone as quasars in the past; the quiescent black holes that we detect now in nearby bulges are the dormant remnants of this fiery past. In this review we report on basic, but critical, questions regarding the cosmological significance of MBHs. What physical mechanisms led to the formation of the first MBHs? How massive were the initial MBH seeds? When and where did they form? How is the growth of black holes linked to that of their host galaxy? The answers to most of these questions are works in progress, in the spirit of these reports on progress in physics.

Black holes in the early Universe

International Nuclear Information System (INIS)

Volonteri, Marta; Bellovary, Jillian

2012-01-01

The existence of massive black holes (MBHs) was postulated in the 1960s, when the first quasars were discovered. In the late 1990s their reality was proven beyond doubt in the Milky way and a handful nearby galaxies. Since then, enormous theoretical and observational efforts have been made to understand the astrophysics of MBHs. We have discovered that some of the most massive black holes known, weighing billions of solar masses, powered luminous quasars within the first billion years of the Universe. The first MBHs must therefore have formed around the time the first stars and galaxies formed. Dynamical evidence also indicates that black holes with masses of millions to billions of solar masses ordinarily dwell in the centers of today's galaxies. MBHs populate galaxy centers today, and shone as quasars in the past; the quiescent black holes that we detect now in nearby bulges are the dormant remnants of this fiery past. In this review we report on basic, but critical, questions regarding the cosmological significance of MBHs. What physical mechanisms led to the formation of the first MBHs? How massive were the initial MBH seeds? When and where did they form? How is the growth of black holes linked to that of their host galaxy? The answers to most of these questions are works in progress, in the spirit of these reports on progress in physics. (review article)

"Less than a Vapor": Positioning Black lesbian women in history teacher education.

Science.gov (United States)

Woodson, Ashley N

2017-10-02

In this article, I discuss the possibilities and implications of centering Black lesbian identities and relationships in history teacher education through a case study with one straight Black woman preservice history teacher named Danitra. Danitra's understanding and navigation of historical research on Black lesbians are discussed in relation to core themes of lesbian historiography and emancipatory historiography. Though the literature on this group is limited, I argue that critical considerations of Black lesbians' interests and experiences help educators to conceive of and teach about history, citizenship, justice, and sexuality in more liberatory ways. I conclude by offering recommendations to history teachers and teacher educators who hope to draw on lesbian and emancipatory historiographies to challenge discourses of invisibility in history teacher education classrooms.

Destroying black holes with test bodies

Energy Technology Data Exchange (ETDEWEB)

Jacobson, Ted [Center for Fundamental Physics, University of Maryland, College Park, MD 20742-4111 (United States); Sotiriou, Thomas P, E-mail: jacobson@umd.ed, E-mail: T.Sotiriou@damtp.cam.ac.u [Department of Applied Mathematics and Theoretical Physics, Centre for Mathematical Sciences, University of Cambridge, Wilberforce Road, Cambridge, CB3 0WA (United Kingdom)

2010-04-01

If a black hole can accrete a body whose spin or charge would send the black hole parameters over the extremal limit, then a naked singularity would presumably form, in violation of the cosmic censorship conjecture. We review some previous results on testing cosmic censorship in this way using the test body approximation, focusing mostly on the case of neutral black holes. Under certain conditions a black hole can indeed be over-spun or over-charged in this approximation, hence radiative and self-force effects must be taken into account to further test cosmic censorship.

Destroying black holes with test bodies

International Nuclear Information System (INIS)

Jacobson, Ted; Sotiriou, Thomas P

2010-01-01

If a black hole can accrete a body whose spin or charge would send the black hole parameters over the extremal limit, then a naked singularity would presumably form, in violation of the cosmic censorship conjecture. We review some previous results on testing cosmic censorship in this way using the test body approximation, focusing mostly on the case of neutral black holes. Under certain conditions a black hole can indeed be over-spun or over-charged in this approximation, hence radiative and self-force effects must be taken into account to further test cosmic censorship.

Masculine ideology, norms, and HIV prevention among young Black men

Science.gov (United States)

Hall, Naomi M.; Applewhite, Sheldon

2014-01-01

This study examines the relationship between masculine ideology, adherence to norms, and HIV prevention among young Black heterosexual and gay men on the campus of a historically Black college/university. The data from four focus groups and nine individual interviews (N = 35) were aggregated and two recurring themes emerged: sexual communication, and mate availability. Additional themes related to HIV prevention were stigma, protection, and testing. The importance of investigating masculinity with young men is highlighted and implications for professionals working with college students to prevent the transmission of HIV are included. PMID:25525415

Masculine ideology, norms, and HIV prevention among young Black men.

Science.gov (United States)

Hall, Naomi M; Applewhite, Sheldon

2013-01-01

This study examines the relationship between masculine ideology, adherence to norms, and HIV prevention among young Black heterosexual and gay men on the campus of a historically Black college/university. The data from four focus groups and nine individual interviews (N = 35) were aggregated and two recurring themes emerged: sexual communication, and mate availability. Additional themes related to HIV prevention were stigma, protection, and testing. The importance of investigating masculinity with young men is highlighted and implications for professionals working with college students to prevent the transmission of HIV are included.

Black brant from Alaska staging and wintering in Japan

Science.gov (United States)

Derksen, Dirk V.; Bollinger, K.S.; Ward, David H.; Sedinger, J.S.; Miyabayashi, Y.

1996-01-01

Black brant (Branta bernicla nigricans) nest in colonies in arctic Canada, Alaska, and Russia (Derksen and Ward 1993, Sedinger et al. 1993). Virtually the entire population stages in fall at Izembek Lagoon near the tip of the Alaska Peninsula (Bellrose 1976) before southward migration (Dau 1992) to winter habitats in British Columbia, Washington, Oregon, California, and Baja California (Subcommittee on Black Brant 1992). A small number of black brant winter in Japan, Korea, and China (Owen 1980). In Japan 3,000–5,000 brant of unknown origin stop over in fall, and a declining population (in the northern islands (Brazil 1991, Miyabayashi et al. 1994). Here, we report sightings of brant in Japan that were marked in Alaska and propose a migration route based on historical and recent observations and weather patterns.

"To Kill a Mockingbird": An Historical Perspective. Learning Page Lesson Plan.

Science.gov (United States)

Prody, Kathleen; Whearty, Nicolet

Students gain from a sense of the living history that surrounds Harper Lee's novel, "To Kill a Mockingbird." Through studying primary source materials from American Memory and other online sources, students of all backgrounds may better grasp how historical events and human forces have shaped relationships between black and white and…

Ninth Annual "Brown" Lecture in Education Research: Black Educators as Educational Advocates in the Decades before "Brown v. Board of Education"

Science.gov (United States)

Walker, Vanessa Siddle

2013-01-01

This research sought to extend the historical record of advocacy for Black education by exploring the role of Black educators in the decades before the "Brown v. Board of Education" decision. It addressed (a) the ways the educators were involved in advocating for Black schools and (b) the relationship of the activities to the more…

Along Freedom Road. Hyde County, North Carolina and the Fate of Black Schools in the South.

Science.gov (United States)

Cecelski, David S.

The 1968-69 school boycott in Hyde County (North Carolina) was one of the most sustained and successful protests of the civil rights movement. For a year, the county's black citizens refused to send their children to school in protest of a desegregation plan that required closing two historically black schools in their remote coastal community.…

Hydrologic modeling of flood conveyance and impacts of historic overbank sedimentation on West Fork Black's Fork, Uinta Mountains, northeastern Utah, USA

Science.gov (United States)

Carson, Eric C.

2006-05-01

This study assesses historic overbank alluvial sedimentation along a low-gradient reach of West Fork Black's Fork in the northern Uinta Mountains, Utah. In this previously glaciated setting, an alluvial floodplain that is approximately 400 m wide by 1500 m long has been modified by the combined effects of valley morphometry and the recent history of clear-cut logging during the late 19th and early 20th Centuries. To quantify the effects on sedimentation and flow conveyance, three natural streambank exposures were sampled and analyzed for nuclear bomb fallout 137Cs. The distribution of 137Cs within the three profiles suggests that a remnant outwash terrace exerts a first-order control over the deposition of overbank alluvium. Upstream from a constriction in the floodplain caused by the terrace remnant, as much as 40 cm of overbank alluvium has been deposited since the beginning of clear-cut logging. Immediately downstream of that constriction, no evidence exists for any overbank sedimentation during that same period. Vibracore samples and Oakfield soil probe sampling throughout the study reach quantified the geographic extent and thicknesses of the historic alluvial package. Flood conveyance through the study area was modeled using the U.S. Army Corps of Engineers HEC-RAS modeling program. Model simulations were run for modern conditions (using surveyed topography) and for prehistoric conditions (using the modern topography less the historic alluvial package determined by 137Cs analyses). Model results indicate that the floodplain constriction caused a significant impediment to flood conveyance at even modest discharges during prehistoric conditions. This promoted ponding of floodwaters upstream of the constriction and deposition of alluvium. This has increased bank heights upstream of the constriction, to the point that under modern conditions 1- to 5-year recurrence interval floods are largely confined within the channel. These results confirm the validity of this

Boundary Spanners and Advocacy Leaders: Black Educators and Race Equality Work in Toronto and London, 1968-1995

Science.gov (United States)

Johnson, Lauri

2016-01-01

This comparative study examines the historical development of race equality efforts during the 1970s and 1980s in two global cities--Toronto and London--and the role of African Canadian and Black British educators in longstanding school-community partnerships. I characterize the leadership stance of Black educators as boundary spanners and…

Why New Hybrid Organizations are Formed: Historical Perspectives on Epistemic and Academic Drift.

Science.gov (United States)

Kaiserfeld, Thomas

2013-06-01

By comparing three types of hybrid organizations-18th-century scientific academies, 19th-century institutions of higher vocational education, and 20th-century industrial research institutes-it is the purpose here to answer the question of why new hybrid organizations are continuously formed. Traditionally, and often implicitly, it is often assumed that emerging groups of potential knowledge users have their own organizational preferences and demands influencing the setup of new hybrid organizations. By applying the concepts epistemic and academic drift, it will be argued here, however, that internal organizational dynamics are just as important as changing historical conjunctures in the uses of science when understanding why new hybrid organizations are formed. Only seldom have older hybrid organizations sought to make themselves relevant to new categories of knowledge users as the original ones have been marginalized. Instead, they have tended to accede to ideals supported by traditional academic organizations with higher status in terms of knowledge management, primarily universities. Through this process, demand has been generated for the founding of new hybrid organizations rather than the transformation of existing ones. Although this study focuses on Swedish cases, it is argued that since Sweden strove consistently to implement existing international policy trends during the periods in question, the observations may be generalized to apply to other national and transnational contexts.

Disease limits populations: plague and black-tailed prairie dogs

Science.gov (United States)

Cully, Jack F.; Johnson, T.; Collinge, S.K.; Ray, C.

2010-01-01

Plague is an exotic vector-borne disease caused by the bacterium Yersinia pestis that causes mortality rates approaching 100% in black-tailed prairie dogs (Cynomys ludovicianus). We mapped the perimeter of the active portions of black-tailed prairie dog colonies annually between 1999 and 2005 at four prairie dog colony complexes in areas with a history of plague, as well as at two complexes that were located outside the distribution of plague at the time of mapping and had therefore never been affected by the disease. We hypothesized that the presence of plague would significantly reduce overall black-tailed prairie dog colony area, reduce the sizes of colonies on these landscapes, and increase nearest-neighbor distances between colonies. Within the region historically affected by plague, individual colonies were smaller, nearest-neighbor distances were greater, and the proportion of potential habitat occupied by active prairie dog colonies was smaller than at plague-free sites. Populations that endured plague were composed of fewer large colonies (>100 ha) than populations that were historically plague free. We suggest that these differences among sites in colony size and isolation may slow recolonization after extirpation. At the same time, greater intercolony distances may also reduce intercolony transmission of pathogens. Reduced transmission among smaller and more distant colonies may ultimately enhance long-term prairie dog population persistence in areas where plague is present.

Event horizon image within black hole shadow

OpenAIRE

Dokuchaev, V. I.; Nazarova, N. O.

2018-01-01

The external border of the black hole shadow is washed out by radiation from matter plunging into black hole and approaching the event horizon. This effect will crucially influence the results of future observations by the Event Horizon Telescope. We show that gravitational lensing of the luminous matter plunging into black hole provides the event horizon visualization within black hole shadow. The lensed image of the event horizon is formed by the last highly red-shifted photons emitted by t...

Black holes and Higgs stability

CERN Document Server

Tetradis, Nikolaos

2016-09-20

We study the effect of primordial black holes on the classical rate of nucleation of AdS regions within the standard electroweak vacuum. We find that the energy barrier for transitions to the new vacuum, which characterizes the exponential suppression of the nucleation rate, can be reduced significantly in the black-hole background. A precise analysis is required in order to determine whether the the existence of primordial black holes is compatible with the form of the Higgs potential at high temperature or density in the Standard Model or its extensions.

Black to Black

DEFF Research Database (Denmark)

Langkjær, Michael Alexander

2012-01-01

Pop musicians performing in black stage costume take advantage of cultural traditions relating to matters black. Stylistically, black is a paradoxical color: although a symbol of melancholy, pessimism, and renunciation, black also expresses minimalist modernity and signifies exclusivity (as is hi...

Black Populations and Identity Issues in Latin America

Directory of Open Access Journals (Sweden)

Peter Wade

2008-02-01

Full Text Available In this article, I explore the basis for black identity in Latin America. I begin with a general consideration of the position of black populations in the framework of Latin American nationalism, taking into account the transnational dimensions of this position and then analyzing in theoretical terms the tension between particularism and universalism in ideologies of nationalism and racism. In the second part of the article, I examine some concrete historical cases of Afrodescendent mobilization and/or opening towards racial diversity in order to evaluate these as bases for a Latin American black identity in general (the racial war in Cuba in 1912, the Frente Negra Brasileira of the 1930s, the Creoles in the Sandinista regime in Nicaragua, the official multiculturalism of various Latin American countries in the 1990s, and the image of “Africa” as the basis for Afrodescendant identification.

Socioeconomic Factors Affecting Local Support for Black Bear Recovery Strategies

Science.gov (United States)

Morzillo, Anita T.; Mertig, Angela G.; Hollister, Jeffrey W.; Garner, Nathan; Liu, Jianguo

2010-06-01

There is global interest in recovering locally extirpated carnivore species. Successful efforts to recover Louisiana black bear in Louisiana have prompted interest in recovery throughout the species’ historical range. We evaluated support for three potential black bear recovery strategies prior to public release of a black bear conservation and management plan for eastern Texas, United States. Data were collected from 1,006 residents living in proximity to potential recovery locations, particularly Big Thicket National Preserve. In addition to traditional logistic regression analysis, we used conditional probability analysis to statistically and visually evaluate probabilities of public support for potential black bear recovery strategies based on socioeconomic characteristics. Allowing black bears to repopulate the region on their own (i.e., without active reintroduction) was the recovery strategy with the greatest probability of acceptance. Recovery strategy acceptance was influenced by many socioeconomic factors. Older and long-time local residents were most likely to want to exclude black bears from the area. Concern about the problems that black bears may cause was the only variable significantly related to support or non-support across all strategies. Lack of personal knowledge about black bears was the most frequent reason for uncertainty about preferred strategy. In order to reduce local uncertainty about possible recovery strategies, we suggest that wildlife managers focus outreach efforts on providing local residents with general information about black bears, as well as information pertinent to minimizing the potential for human-black bear conflict.

Thermodynamic theory of black holes

Energy Technology Data Exchange (ETDEWEB)

Davies, P C.W. [King' s Coll., London (UK). Dept. of Mathematics

1977-04-21

The thermodynamic theory underlying black hole processes is developed in detail and applied to model systems. It is found that Kerr-Newman black holes undergo a phase transition at a = 0.68M or Q = 0.86M, where the heat capacity has an infinite discontinuity. Above the transition values the specific heat is positive, permitting isothermal equilibrium with a surrounding heat bath. Simple processes and stability criteria for various black hole situations are investigated. The limits for entropically favoured black hole formation are found. The Nernst conditions for the third law of thermodynamics are not satisfied fully for black holes. There is no obvious thermodynamic reason why a black hole may not be cooled down below absolute zero and converted into a naked singularity. Quantum energy-momentum tensor calculations for uncharged black holes are extended to the Reissner-Nordstrom case, and found to be fully consistent with the thermodynamic picture for Q < M. For Q < M the model predicts that 'naked' collapse also produces radiation, with such intensity that the collapsing matter is entirely evaporated away before a naked singularity can form.

Senior Level Administrators and HBCUs: The Role of Support for Black Women’s Success in STEM

Directory of Open Access Journals (Sweden)

Amanda Washington Lockett

2018-04-01

Full Text Available While it is important for college and university senior administrators to embrace the traditional roles of their administrative positions, senior administrators’ interactions with students also shape institutional culture, students’ engagement, and ultimately play a role in students’ motivation to succeed. This engagement is especially evident in the Historically Black College and University (HBCU context as senior administrators’ engagement with students can directly or indirectly affect how students perceive themselves and their ability to succeed. This article aims to illuminate the role that HBCU senior level administrators play in students’ motivation toward success. We also highlight the notion that senior level administrators’ role in organizational culture ultimately led historically-disempowered Black women students toward success in even the most historically inaccessible pathways in the science, technology, engineering, and math (STEM fields. The study used semi-structured interviews with 71 Black women STEM students across 10 HBCUs and asked questions to better understand how events in their lives and on their campuses shaped their choice to pursue and persist through a STEM degree program. The study found that the women were highly motivated by their HBCUs’ family-like community of support. Integral to this article, this support was not confined to professors and peers, but extended to senior administrators. We conclude that Black women STEM students’ perception of their ability to succeed and their motivation is influenced by the institutions’ senior administration.

Black holes, pregalactic stars, and the dark matter problem

International Nuclear Information System (INIS)

Carr, B.J.

1985-06-01

We review the different ways in which black holes might form and discuss their various astrophysical and cosmological consequences. We then consider the various constraints on the form of the dark matter and conclude that black holes could have a significant cosmological density only if they are of primordial origin or remnants of a population of pregalactic stars. This leads us to discuss the other cosmological effects of primordial black holes and pregalactic stars. 239 refs., 7 figs., 5 tabs

GRAVITATIONAL WAVE SIGNATURES IN BLACK HOLE FORMING CORE COLLAPSE

Energy Technology Data Exchange (ETDEWEB)

Cerdá-Durán, Pablo; DeBrye, Nicolas; Aloy, Miguel A.; Font, José A.; Obergaulinger, Martin, E-mail: pablo.cerda@uv.es [Departamento de Astronomia y Astrofísica, Universidad de Valencia, c/Dr. Moliner 50, E-46100-Burjassot (Spain)

2013-12-20

We present general relativistic numerical simulations of collapsing stellar cores. Our initial model consists of a low metallicity rapidly-rotating progenitor which is evolved in axisymmetry with the latest version of our general relativistic code CoCoNuT, which allows for black hole formation and includes the effects of a microphysical equation of state (LS220) and a neutrino leakage scheme to account for radiative losses. The motivation of our study is to analyze in detail the emission of gravitational waves in the collapsar scenario of long gamma-ray bursts. Our simulations show that the phase during which the proto-neutron star (PNS) survives before ultimately collapsing to a black hole is particularly optimal for gravitational wave emission. The high-amplitude waves last for several seconds and show a remarkable quasi-periodicity associated with the violent PNS dynamics, namely during the episodes of convection and the subsequent nonlinear development of the standing-accretion shock instability (SASI). By analyzing the spectrogram of our simulations we are able to identify the frequencies associated with the presence of g-modes and with the SASI motions at the PNS surface. We note that the gravitational waves emitted reach large enough amplitudes to be detected with third-generation detectors such as the Einstein Telescope within a Virgo Cluster volume at rates ≲ 0.1 yr{sup –1}.

Black Edens, country Eves: Listening, performance, and black queer longing in country music.

Science.gov (United States)

Royster, Francesca T

2017-07-03

This article explores Black queer country music listening, performance, and fandom as a source of pleasure, nostalgia, and longing for Black listeners. Country music can be a space for alliance and community, as well as a way of accessing sometimes repressed cultural and personal histories of violence: lynching and other forms of racial terror, gender surveillance and disciplining, and continued racial and economic segregation. For many Black country music listeners and performers, the experience of being a closeted fan also fosters an experience of ideological hailing, as well as queer world-making. Royster suggests that through Black queer country music fandom and performance, fans construct risky and soulful identities. The article uses Tina Turner's solo album, Tina Turns the Country On! (1974) as an example of country music's power as a tool for resistance to racial, sexual, and class disciplining.

Einstein's Enigma of black holes in my bubble bath

International Nuclear Information System (INIS)

Vishveshwara, C.

2006-01-01

Einstein's Enigma or Black Holes in My Bubble Bath is a humorous and informal rendition of the story of gravitation theory from the early historic origins to the latest developments in astrophysics, focusing on Albert Einstein's theory of general relativity and black-hole physics. Through engaging conversations and napkin-scribbled diagrams come tumbling the rudiments of relativity, spacetime and much of modern physics, narrated with high didactic and literary talent, and each embedded in casual lessons given by a worldly astrophysicist to his friend. Join the intellectual fun and exalt in the frothy ideas while vicariously taking relaxing baths in this magical bathtub. (orig.)

Historical Slovenian Language Resources

Directory of Open Access Journals (Sweden)

Tomaž Erjavec

2013-09-01

Full Text Available EXTENDED ABSTRACT:The paper presents three language resources enabling better full-text access to digitised printed historical Slovenian texts: a hand-annotated corpus, a hand-annotated lexicon of historical words and a collection of transcribed texts. The aim of the resources is twofold: on one hand they support empirical linguistic research (corpus, collection and represent a reference tool for the research of historical Slovenian (lexicon while on the other hand they may serve as training data for the development of Human Language Technologies enabling better full-text search in digital libraries containing Slovenian written cultural heritage, modernisation of historical texts, and the development of better technological solutions for text recognition and scanning. The hand annotated corpus of historical Slovenian contains the text from 1,000 pages sampled from the years 1750 to 1900, two texts date to the end of the 16th or 17th century. The corpus contains a little more than 250,000 word tokens; each of them being annotated with hand validated linguistic features: modernised form, lemma or base form, and morhpo-syntactic description. Thus the word token »ajfram« is annotated with the normalised form »ajfrom«, by the lemma »ajfer« and morphosyntactic description »Som« or »Samostalnik« (noun, »občni« (common, »moški« (masculine and a modernised form »gorečnost« (fervour. At first the corpus was annotated automatically and then manually verified and corrected. The lexicon was created automatically from the hand-annotated corpus. It contains only attested word-forms and examples of use. The word-forms are ordered under their modern equivalents. All the modern forms of a particular word constitute a dictionary entry, defined by its lemma with conjoint information i.e. the morpho-syntactic description and the closest contemporary synonyms. Thus the entry »ajfrer/Som/gorečnost« is annotated by two modernised words »ajfra �

From “brute” to “thug:” the demonization and criminalization of unarmed Black male victims in America

Science.gov (United States)

Smiley, CalvinJohn; Fakunle, David

2016-01-01

The synonymy of Blackness with criminality is not a new phenomenon in America. Documented historical accounts have shown how myths, stereotypes, and racist ideologies led to discriminatory policies and court rulings that fueled racial violence in a post-Reconstruction era and has culminated in the exponential increase of Black male incarceration today. Misconceptions and prejudices manufactured and disseminated through various channels such as the media included references to a “brute” image of Black males. In the 21st century, this negative imagery of Black males has frequently utilized the negative connotation of the terminology “thug.” In recent years, law enforcement agencies have unreasonably used deadly force on Black males allegedly considered to be “suspects” or “persons of interest.” The exploitation of these often-targeted victims' criminal records, physical appearances, or misperceived attributes has been used to justify their unlawful deaths. Despite the connection between disproportionate criminality and Black masculinity, little research has been done on how unarmed Black male victims, particularly but not exclusively at the hands of law enforcement, have been posthumously criminalized. This paper investigates the historical criminalization of Black males and its connection to contemporary unarmed victims of law enforcement. Action research methodology in the data collection process is utilized to interpret how Black male victims are portrayed by traditional mass media, particularly through the use of language, in ways that marginalize and de-victimize these individuals. This study also aims to elucidate a contemporary understanding of race relations, racism, and the plight of the Black male in a 21-century “post-racial” America. PMID:27594778

Family identity: black-white interracial family health experience.

Science.gov (United States)

Byrd, Marcia Marie; Garwick, Ann Williams

2006-02-01

The purpose of this interpretive descriptive study was to describe how eight Black-White couples with school-aged children constructed their interracial family identity through developmental transitions and interpreted race to their children. Within and across-case data analytic strategies were used to identify commonalities and variations in how Black men and White women in couple relationships formed their family identities over time. Coming together was the core theme described by the Black-White couples as they negotiated the process of forming a family identity. Four major tasks in the construction of interracial family identity emerged: (a) understanding and resolving family of origin chaos and turmoil, (b) transcending Black-White racial history, (c) articulating the interracial family's racial standpoint, and (d) explaining race to biracial children across the developmental stages. The findings guide family nurses in promoting family identity formation as a component of family health within the nurse-family partnership with Black-White mixed-race families.

Remnant for all black objects due to gravity's rainbow

Energy Technology Data Exchange (ETDEWEB)

Ali, Ahmed Farag, E-mail: afarag@zewailcity.edu.eg [Department of Physics, Florida State University, Tallahassee, FL 32306 (United States); Center for Fundamental Physics, Zewail City of Science and Technology, Giza 12588 (Egypt); Department of Physics, Faculty of Science, Benha University, Benha 13518 (Egypt); Faizal, Mir, E-mail: f2mir@uwaterloo.ca [Department of Physics and Astronomy, University of Waterloo, Waterloo, Ontario, N2L 3G1 (Canada); Khalil, Mohammed M., E-mail: moh.m.khalil@gmail.com [Department of Electrical Engineering, Alexandria University, Alexandria 12544 (Egypt)

2015-05-15

We argue that a remnant is formed for all black objects in gravity's rainbow. This will be based on the observation that a remnant depends critically on the structure of the rainbow functions, and this dependence is a model independent phenomena. We thus propose general relations for the modified temperature and entropy of all black objects in gravity's rainbow. We explicitly check this to be the case for Kerr, Kerr–Newman-dS, charged-AdS, and higher dimensional Kerr–AdS black holes. We also try to argue that a remnant should form for black saturn in gravity's rainbow. This work extends our previous results on remnants of Schwarzschild black holes and black rings.

Entropy of black holes with multiple horizons

Science.gov (United States)

He, Yun; Ma, Meng-Sen; Zhao, Ren

2018-05-01

We examine the entropy of black holes in de Sitter space and black holes surrounded by quintessence. These black holes have multiple horizons, including at least the black hole event horizon and a horizon outside it (cosmological horizon for de Sitter black holes and "quintessence horizon" for the black holes surrounded by quintessence). Based on the consideration that the two horizons are not independent each other, we conjecture that the total entropy of these black holes should not be simply the sum of entropies of the two horizons, but should have an extra term coming from the correlations between the two horizons. Different from our previous works, in this paper we consider the cosmological constant as the variable and employ an effective method to derive the explicit form of the entropy. We also try to discuss the thermodynamic stabilities of these black holes according to the entropy and the effective temperature.

Black hole entropy, curved space and monsters

International Nuclear Information System (INIS)

Hsu, Stephen D.H.; Reeb, David

2008-01-01

We investigate the microscopic origin of black hole entropy, in particular the gap between the maximum entropy of ordinary matter and that of black holes. Using curved space, we construct configurations with entropy greater than the area A of a black hole of equal mass. These configurations have pathological properties and we refer to them as monsters. When monsters are excluded we recover the entropy bound on ordinary matter S 3/4 . This bound implies that essentially all of the microstates of a semiclassical black hole are associated with the growth of a slightly smaller black hole which absorbs some additional energy. Our results suggest that the area entropy of black holes is the logarithm of the number of distinct ways in which one can form the black hole from ordinary matter and smaller black holes, but only after the exclusion of monster states

Recovering from "Yo Mama Is so Stupid": (En)gendering a Critical Paradigm on Black Feminist Theory and Pedagogy

Science.gov (United States)

Brock, Rochelle

2011-01-01

This article offers an analysis of the dozens using Black feminist theory. The dozens are a ritualized verbal game of insults that historically have used sexual offenses against Black women as the vehicle for insults. Rather than simply viewing the dozens as a cultural phenomenon, the article draws a connection between its occurrence in West…

If This Is a "Real" Housewife, Who Are All These Women Around Me?: An Examination of The Real Housewives of Atlanta and the Persistence of Historically Stereotypical Images of Black Women in Popular Reality Television.

OpenAIRE

Bunai, Dominique Christabel

2014-01-01

Stereotypical images of blacks have persisted throughout multiple forms of media for decades, with one of the most recent arenas being reality television programming. This study examines the Bravo Television network series The Real Housewives of Atlanta to consider the impact of reality television on the image of black women in America today. This increasingly popular show is the most viewed in The Real Housewives franchise, and demonstrates that black women in America do not embody any one h...

Binary Black Hole Mergers from Globular Clusters: Implications for Advanced LIGO.

Science.gov (United States)

Rodriguez, Carl L; Morscher, Meagan; Pattabiraman, Bharath; Chatterjee, Sourav; Haster, Carl-Johan; Rasio, Frederic A

2015-07-31

The predicted rate of binary black hole mergers from galactic fields can vary over several orders of magnitude and is extremely sensitive to the assumptions of stellar evolution. But in dense stellar environments such as globular clusters, binary black holes form by well-understood gravitational interactions. In this Letter, we study the formation of black hole binaries in an extensive collection of realistic globular cluster models. By comparing these models to observed Milky Way and extragalactic globular clusters, we find that the mergers of dynamically formed binaries could be detected at a rate of ∼100 per year, potentially dominating the binary black hole merger rate. We also find that a majority of cluster-formed binaries are more massive than their field-formed counterparts, suggesting that Advanced LIGO could identify certain binaries as originating from dense stellar environments.

REGIONAL COOPERATION IN THE BLACK SEA BASIN

Directory of Open Access Journals (Sweden)

Anastasiia GAVUIK

2015-07-01

Full Text Available Topicality. The Black Sea region is situated in a very important geopolitical manner. Consequently, a large-scale regional collaboration becomes possible within the Black Sea zone and countries get appropriate conditions to launch their activity in this context. Aim: The body of the article is going to analyze the BSEC as one of the most successful regional organizations in the Black Sea area. The paper aims to provide an overview of the regional players’ activity in the framework of the BSEC which are involved in sustaining and strengthening of this organization and also in continuing the reform process in it, developing in the same time relations of cooperation with the EU and other regional initiatives. Methods. This article embraces a row of different scientific methods of data analysis, predictive analytics, historical and statistical overview, descriptive method, case study etc. Results. The countries from the Black Sea basin are the most vulnerable to potential risks and shocks due to the instability of the region. This requires the interstate cooperation in the Black Sea area with no tradition in this field several decades ago. In the same time, countries like Turkey, Romania or Russia aspire to play the role of the regional leader, which can cause regional rivalries. With the help of the regional cooperation and the BSEC in particular, regional countries could learn how to work together for the common benefit. The creation of stable markets, interconnected and transparent regional organizations and initiatives would largely contribute to the security and stability of the Black Sea region.

Historiography of the Epidemic of “Black Death” on the Territory of Juchid Ulus (1814–2016

Directory of Open Access Journals (Sweden)

T.F. Khaydarov

2017-03-01

thorough theoretical study of a subject in the field of biology of the plague, a historical study on the “Black Death in Russia” is extremely inconsistent and did not yet form a united research school. Against this background, the historiography of the epidemic “Black Death” in the Juchid ulus is situated in a better position than the research on the plague in the North-Western Rus’.

Action growth for black holes in modified gravity

Science.gov (United States)

Sebastiani, Lorenzo; Vanzo, Luciano; Zerbini, Sergio

2018-02-01

The general form of the action growth for a large class of static black hole solutions in modified gravity which includes F (R ) -gravity models is computed. The cases of black hole solutions with nonconstant Ricci scalar are also considered, generalizing the results previously found and valid only for black holes with constant Ricci scalar. An argument is put forward to provide a physical interpretation of the results, which seem tightly connected with the generalized second law of black hole thermodynamics.

Entropy of black holes with multiple horizons

Directory of Open Access Journals (Sweden)

Yun He

2018-05-01

Full Text Available We examine the entropy of black holes in de Sitter space and black holes surrounded by quintessence. These black holes have multiple horizons, including at least the black hole event horizon and a horizon outside it (cosmological horizon for de Sitter black holes and “quintessence horizon” for the black holes surrounded by quintessence. Based on the consideration that the two horizons are not independent each other, we conjecture that the total entropy of these black holes should not be simply the sum of entropies of the two horizons, but should have an extra term coming from the correlations between the two horizons. Different from our previous works, in this paper we consider the cosmological constant as the variable and employ an effective method to derive the explicit form of the entropy. We also try to discuss the thermodynamic stabilities of these black holes according to the entropy and the effective temperature.

Training the Next Generation: Developing Health Education Skills in Undergraduate Public Health Students at a Historically Black College and University

Directory of Open Access Journals (Sweden)

Krista Mincey

2017-10-01

Full Text Available With the looming workforce crisis, undergraduate public health students could be an important link in filling this demand. As public health continues to face challenges in the future, it is important that the future workforce is not only diverse but also trained in a manner that exposes them to real-world experiences that give them an opportunity to apply coursework to solve problems. This article outlines how a health program planning course was taught at a Historically Black College and University using assignments that promote active learning. Students were assessed on their ability to plan and implement a health activity based on a developed metric. Student and instructor reflections were collected from final assessments of the health programs by both groups. All elements of the course are discussed from course design, structure, assignments, and outcomes along with student and instructor reflections and lessons learned. Results suggest that including assignments focused on active learning are beneficial to helping students learn course material. As public health continues to change, more work needs to focus on teaching pedagogies that better prepare students to address future public health issues.

Black holes by analytic continuation

CERN Document Server

Amati, Daniele

1997-01-01

In the context of a two-dimensional exactly solvable model, the dynamics of quantum black holes is obtained by analytically continuing the description of the regime where no black hole is formed. The resulting spectrum of outgoing radiation departs from the one predicted by the Hawking model in the region where the outgoing modes arise from the horizon with Planck-order frequencies. This occurs early in the evaporation process, and the resulting physical picture is unconventional. The theory predicts that black holes will only radiate out an energy of Planck mass order, stabilizing after a transitory period. The continuation from a regime without black hole formation --accessible in the 1+1 gravity theory considered-- is implicit in an S matrix approach and provides in this way a possible solution to the problem of information loss.

The Challenges and Success of Implementing Climate Studies Lessons for Pre-Professional Teachers at a Small Historically Black College to Engage Student Teaching of Science Pedagogy and Content Skill Based Learning.

Science.gov (United States)

Arnold, J.; Wider-Lewis, F.; Miller-Jenkins, A.

2017-12-01

This poster is a description of the challenges and success of implementing climate studies lessons for pre-service teachers to engage student teaching pedagogy and content skill based learning. Edward Waters College is a historical black college with an elementary education teacher program focused on urban elementary school teaching and learning. Pre-Service Elementary Educator Students often have difficulty with science and mathematics content and pedagogy. This poster will highlight the barriers and successes of using climate studies lessons to develop and enhance pre-service teachers' knowledge of elementary science principles particularly related to climate studies, physical and earth space science.

Rotating black holes in dilatonic Einstein-Gauss-Bonnet theory.

Science.gov (United States)

Kleihaus, Burkhard; Kunz, Jutta; Radu, Eugen

2011-04-15

We construct generalizations of the Kerr black holes by including higher-curvature corrections in the form of the Gauss-Bonnet density coupled to the dilaton. We show that the domain of existence of these Einstein-Gauss-Bonnet-dilaton (EGBD) black holes is bounded by the Kerr black holes, the critical EGBD black holes, and the singular extremal EGBD solutions. The angular momentum of the EGBD black holes can exceed the Kerr bound. The EGBD black holes satisfy a generalized Smarr relation. We also compare their innermost stable circular orbits with those of the Kerr black holes and show the existence of differences which might be observable in astrophysical systems.

The Black Rock Forest Consortium: A narrative

Science.gov (United States)

Buzzetto-More, Nicole Antoinette

The Black Rock Forest is a 3,785-acre wilderness area whose richly forested landscape represents the splendor of the Hudson Valley Region of New York State. Although originally intended to become the home of wealthy banker James Stillman, it was his son Ernest whose love of conservation caused him to embrace the then new and revolutionary practice of sustainable forestry and establish Black Rock in 1928. Due to Ernest Stillman's foresight, the property was protected from development and bequeathed to Harvard University following his death for the establishment of an experimental forest. The modern environmental movement in America began when the Black Rock Forest was threatened with development by Consolidated Edison, and the people of the surrounding community banded together, battling tirelessly for over 17 years to stop the degradation of this historic forest. The outcome of this crusade marked a hallmark win for the environment leaving an illustrious and inveterate legacy. The campaign resulted in the watershed legislation the National Environmental Policy Act, the formation of several environmental advocacy groups, the creation of the Council on Environmental Quality of the Executive Office of the President, as well as set a precedent for communities to initiate and win cases against major corporations in order to safeguard natural resources. In the midst of the controversy it became apparent that alternative futures for the Forest needed to be explored. As a result of a committee report and one man's vision, the idea emerged to create a consortium that would purchase and steward the Forest. With a formation that took nearly fifteen years, the Black Rock Forest Consortium was formed, a unique amalgamation of K--12 public and private schools, colleges and universities, and science and cultural centers that successfully collaborate to enhance scientific research, environmental conservation, and education. The Consortium works to bridge the gaps between learners

Stereotypes of Black American Women Related to Sexuality and Motherhood

Science.gov (United States)

Rosenthal, Lisa; Lobel, Marci

2016-01-01

Intersectionality theorists and researchers suggest the importance of examining unique stereotypes associated with intersecting group identities. We focus on the unique stereotypes of Black women in the United States related to sexuality and motherhood. In an online experimental study, 435 undergraduates from a Northeastern U.S. university were randomly assigned to one of the four conditions in which they viewed a photograph and read a description of a target young woman. The target’s race (Black vs. White) and pregnancy status (pregnant vs. no pregnancy information) were varied. A Black female target (pregnant or not) was perceived more negatively on items related to historically rooted societal stereotypes about sexual activity, sexual risk, motherhood status, and socioeconomic status than was a White female target, but there were no differences on items unrelated to societal stereotypes. A Black target described as pregnant was also perceived as more likely to be a single mother and to need public assistance than was a White target described as pregnant. Current findings, along with evidence that societal stereotypes have damaging effects, underscore the importance of diversifying images of Black women and increasing awareness of how stereotypes affect perceptions of Black women. Findings also highlight the value of research employing intersectionality to understand stereotypes. PMID:27821904

Stereotypes of Black American Women Related to Sexuality and Motherhood.

Science.gov (United States)

Rosenthal, Lisa; Lobel, Marci

2016-09-01

Intersectionality theorists and researchers suggest the importance of examining unique stereotypes associated with intersecting group identities. We focus on the unique stereotypes of Black women in the United States related to sexuality and motherhood. In an online experimental study, 435 undergraduates from a Northeastern U.S. university were randomly assigned to one of the four conditions in which they viewed a photograph and read a description of a target young woman. The target's race (Black vs. White) and pregnancy status (pregnant vs. no pregnancy information) were varied. A Black female target (pregnant or not) was perceived more negatively on items related to historically rooted societal stereotypes about sexual activity, sexual risk, motherhood status, and socioeconomic status than was a White female target, but there were no differences on items unrelated to societal stereotypes. A Black target described as pregnant was also perceived as more likely to be a single mother and to need public assistance than was a White target described as pregnant. Current findings, along with evidence that societal stereotypes have damaging effects, underscore the importance of diversifying images of Black women and increasing awareness of how stereotypes affect perceptions of Black women. Findings also highlight the value of research employing intersectionality to understand stereotypes.

Stochastic Gravitational-Wave Background due to Primordial Binary Black Hole Mergers.

Science.gov (United States)

Mandic, Vuk; Bird, Simeon; Cholis, Ilias

2016-11-11

Recent Advanced LIGO detections of binary black hole mergers have prompted multiple studies investigating the possibility that the heavy GW150914 binary system was of primordial origin, and hence could be evidence for dark matter in the form of black holes. We compute the stochastic background arising from the incoherent superposition of such primordial binary black hole systems in the Universe and compare it to the similar background spectrum due to binary black hole systems of stellar origin. We investigate the possibility of detecting this background with future gravitational-wave detectors, and conclude that constraining the dark matter component in the form of black holes using stochastic gravitational-wave background measurements will be very challenging.

Fermion tunneling from higher-dimensional black holes

International Nuclear Information System (INIS)

Lin Kai; Yang Shuzheng

2009-01-01

Via the semiclassical approximation method, we study the 1/2-spin fermion tunneling from a higher-dimensional black hole. In our work, the Dirac equations are transformed into a simple form, and then we simplify the fermion tunneling research to the study of the Hamilton-Jacobi equation in curved space-time. Finally, we get the fermion tunneling rates and the Hawking temperatures at the event horizon of higher-dimensional black holes. We study fermion tunneling of a higher-dimensional Schwarzschild black hole and a higher-dimensional spherically symmetric quintessence black hole. In fact, this method is also applicable to the study of fermion tunneling from four-dimensional or lower-dimensional black holes, and we will take the rainbow-Finsler black hole as an example in order to make the fact explicit.

Hawking temperature of constant curvature black holes

International Nuclear Information System (INIS)

Cai Ronggen; Myung, Yun Soo

2011-01-01

The constant curvature (CC) black holes are higher dimensional generalizations of Banados-Teitelboim-Zanelli black holes. It is known that these black holes have the unusual topology of M D-1 xS 1 , where D is the spacetime dimension and M D-1 stands for a conformal Minkowski spacetime in D-1 dimensions. The unusual topology and time-dependence for the exterior of these black holes cause some difficulties to derive their thermodynamic quantities. In this work, by using a globally embedding approach, we obtain the Hawking temperature of the CC black holes. We find that the Hawking temperature takes the same form when using both the static and global coordinates. Also, it is identical to the Gibbons-Hawking temperature of the boundary de Sitter spaces of these CC black holes.

“How It’s Done”: The Role of Mentoring and Advice in Preparing the Next Generation of Historically Black College and University Presidents

Directory of Open Access Journals (Sweden)

Felecia Commodore

2016-06-01

Full Text Available The college and university presidency is one of the most coveted positions in academe. Due to the projected retirements of current Historically Black College and University (HBCU presidents, the researchers interviewed 21 current presidents, institutional board members, and presidential search firm personnel to explore what current HBCU leadership identifies as important mentoring/mentee practices, mentoring/mentee opportunities, and professional advice for HBCU presidential aspirants to consider. The findings, based on the coding and analysis of semi-structured qualitative interviews, revealed that self-awareness, focusing on the essential aspects of the job and not merely the perks, openness to being mentored and willingness to shadow a successful leader, experience in serving in various administrative capacities, participating in professional leadership development activities, earning of a terminal degree, displaying humility, understanding academic politics, and learning how to present oneself as an executive is important in the preparation of a leader of an HBCU.

LIGO Discovers the Merger of Two Black Holes

Science.gov (United States)

Kohler, Susanna

2016-02-01

Big news: the Laser Interferometer Gravitational-Wave Observatory (LIGO) has detected its first gravitational-wave signal! Not only is the detection of this signal a major technical accomplishment and an exciting confirmation of general relativity, but it also has huge implications for black-hole astrophysics.What did LIGO see?LIGO is designed to detect the ripples in space-time created by two massive objects orbiting each other. These waves can reach observable amplitudes when a binary system consisting of two especially massive objects i.e., black holes or neutron stars reach the end of their inspiral and merge.LIGO has been unsuccessfully searching for gravitational waves since its initial operations in 2002, but a recent upgrade in its design has significantly increased its sensitivity and observational range. The first official observing run of Advanced LIGO began 18 September 2015, but the instruments were up and running in engineering mode several weeks before that. And it was in this time frame before official observing even began! that LIGO spotted its first gravitational wave signal: GW150914.One of LIGOs two detection sites, located near Hanford in eastern Washington. [LIGO]The signal, detected on 14 September, 2015, provides astronomers with a remarkable amount of information about the merger that caused it. From the detection, the LIGO team has extracted the masses of the two black holes that merged, 36+5-4 and 29+4-4 solar masses, as well as the mass of the final black hole formed by the merger, ~62 solar masses. The team also determined that the merger happened roughly a billion light-years away (at a redshift of z~0.1), and the direction of the signal was localized to an area of ~600 square degrees (roughly 1% of the sky).Why is this detection a big deal?This is the firstdirect detection of gravitational waves, providing spectacular further confirmation of Einsteins theory of general relativity. But the implications of GW150914 go far beyond this

Deforming black hole and cosmological solutions by quasiperiodic and/or pattern forming structures in modified and Einstein gravity

Science.gov (United States)

Bubuianu, Laurenţiu; Vacaru, Sergiu I.

2018-05-01

We elaborate on the anholonomic frame deformation method, AFDM, for constructing exact solutions with quasiperiodic structure in modified gravity theories, MGTs, and general relativity, GR. Such solutions are described by generic off-diagonal metrics, nonlinear and linear connections and (effective) matter sources with coefficients depending on all spacetime coordinates via corresponding classes of generation and integration functions and (effective) matter sources. There are studied effective free energy functionals and nonlinear evolution equations for generating off-diagonal quasiperiodic deformations of black hole and/or homogeneous cosmological metrics. The physical data for such functionals are stated by different values of constants and prescribed symmetries for defining quasiperiodic structures at cosmological scales, or astrophysical objects in nontrivial gravitational backgrounds some similar forms as in condensed matter physics. It is shown how quasiperiodic structures determined by general nonlinear, or additive, functionals for generating functions and (effective) sources may transform black hole like configurations into cosmological metrics and inversely. We speculate on possible implications of quasiperiodic solutions in dark energy and dark matter physics. Finally, it is concluded that geometric methods for constructing exact solutions consist an important alternative tool to numerical relativity for investigating nonlinear effects in astrophysics and cosmology.

Black hole formation in a contracting universe

Energy Technology Data Exchange (ETDEWEB)

Quintin, Jerome; Brandenberger, Robert H., E-mail: jquintin@physics.mcgill.ca, E-mail: rhb@hep.physics.mcgill.ca [Department of Physics, McGill University, 3600 rue University, Montréal, QC, H3A 2T8 Canada (Canada)

2016-11-01

We study the evolution of cosmological perturbations in a contracting universe. We aim to determine under which conditions density perturbations grow to form large inhomogeneities and collapse into black holes. Our method consists in solving the cosmological perturbation equations in complete generality for a hydrodynamical fluid. We then describe the evolution of the fluctuations over the different length scales of interest and as a function of the equation of state for the fluid, and we explore two different types of initial conditions: quantum vacuum and thermal fluctuations. We also derive a general requirement for black hole collapse on sub-Hubble scales, and we use the Press-Schechter formalism to describe the black hole formation probability. For a fluid with a small sound speed (e.g., dust), we find that both quantum and thermal initial fluctuations grow in a contracting universe, and the largest inhomogeneities that first collapse into black holes are of Hubble size and the collapse occurs well before reaching the Planck scale. For a radiation-dominated fluid, we find that no black hole can form before reaching the Planck scale. In the context of matter bounce cosmology, it thus appears that only models in which a radiation-dominated era begins early in the cosmological evolution are robust against the formation of black holes. Yet, the formation of black holes might be an interesting feature for other models. We comment on a number of possible alternative early universe scenarios that could take advantage of this feature.

Black hole formation in a contracting universe

International Nuclear Information System (INIS)

Quintin, Jerome; Brandenberger, Robert H.

2016-01-01

We study the evolution of cosmological perturbations in a contracting universe. We aim to determine under which conditions density perturbations grow to form large inhomogeneities and collapse into black holes. Our method consists in solving the cosmological perturbation equations in complete generality for a hydrodynamical fluid. We then describe the evolution of the fluctuations over the different length scales of interest and as a function of the equation of state for the fluid, and we explore two different types of initial conditions: quantum vacuum and thermal fluctuations. We also derive a general requirement for black hole collapse on sub-Hubble scales, and we use the Press-Schechter formalism to describe the black hole formation probability. For a fluid with a small sound speed (e.g., dust), we find that both quantum and thermal initial fluctuations grow in a contracting universe, and the largest inhomogeneities that first collapse into black holes are of Hubble size and the collapse occurs well before reaching the Planck scale. For a radiation-dominated fluid, we find that no black hole can form before reaching the Planck scale. In the context of matter bounce cosmology, it thus appears that only models in which a radiation-dominated era begins early in the cosmological evolution are robust against the formation of black holes. Yet, the formation of black holes might be an interesting feature for other models. We comment on a number of possible alternative early universe scenarios that could take advantage of this feature.

Seeding black holes in cosmological simulations

Science.gov (United States)

Taylor, P.; Kobayashi, C.

2014-08-01

We present a new model for the formation of black holes in cosmological simulations, motivated by the first star formation. Black holes form from high density peaks of primordial gas, and grow via both gas accretion and mergers. Massive black holes heat the surrounding material, suppressing star formation at the centres of galaxies, and driving galactic winds. We perform an investigation into the physical effects of the model parameters, and obtain a `best' set of these parameters by comparing the outcome of simulations to observations. With this best set, we successfully reproduce the cosmic star formation rate history, black hole mass-velocity dispersion relation, and the size-velocity dispersion relation of galaxies. The black hole seed mass is ˜103 M⊙, which is orders of magnitude smaller than that which has been used in previous cosmological simulations with active galactic nuclei, but suggests that the origin of the seed black holes is the death of Population III stars.

Historical analysis of Newfoundland dog fur colour genetics

OpenAIRE

Bondeson, J.

2015-01-01

This article makes use of digitized historic newspapers to analyze Newfoundland dog fur colour genetics, and fur colour variations over time. The results indicate that contrary to the accepted view, the ‘Solid’ gene was introduced into the British population of Newfoundland dogs in the 1840s. Prior to that time, the dogs were white and black (Landseer) or white and brown, and thus spotted/spotted homozygotes. Due to ‘Solid’ being dominant over ‘spotted’, and selective breeding, today the majo...

Trayvon Martin: Racial Profiling, Black Male Stigma, and Social Work Practice.

Science.gov (United States)

Teasley, Martell Lee; Schiele, Jerome H; Adams, Charles; Okilwa, Nathern S

2018-01-01

To address a critical gap in the social work literature, this article examines the deleterious effects of racial profiling as it pertains to police targeting of male African Americans. The authors use the Trayvon Martin court case to exemplify how racial profiling and black male stigma help perpetuate social inequality and injustice for black men. A racism-centered perspective is examined historically and contemporarily as a theoretical approach to understanding the role that race plays in social injustice through racial profiling. Implications for social work research design and practice aimed at increasing the social work knowledge base on racial profiling are discussed. The authors call for attention and advocacy by major social work organizations in the reduction of black male stigma and racial profiling. © 2017 National Association of Social Workers.

Grumblings from an Awakening Black Hole

Science.gov (United States)

Kohler, Susanna

2015-11-01

In June of this year, after nearly three decades of sleep, the black hole V404 Cygni woke up and began grumbling. Scientists across the globe scrambled to observe the sudden flaring activity coming from this previously peaceful black hole. And now were getting the first descriptions of what weve learned from V404 Cygs awakening!Sudden OutburstV404 Cyg is a black hole of roughly nine solar masses, and its in a binary system with a low-mass star. The black hole pulls a stream of gas from the star, which then spirals in around the black hole, forming an accretion disk. Sometimes the material simply accumulates in the disk but every two or three decades, the build-up of gas suddenly rushes toward the black hole as if a dam were bursting.The sudden accretion in these events causes outbursts of activity from the black hole, its flaring easily visible to us. The last time V404 Cyg exhibited such activity was in 1989, and its been rather quiet since then. Our telescopes are of course much more powerful and sensitive now, nearly three decades later so when the black hole woke up and began flaring in June, scientists were delighted at the chance to observe it.The high variability of V404 Cyg is evident in this example set of spectra, where time increases from the bottom panel to the top. [King et al. 2015]Led by Ashley King (Einstein Fellow at Stanford University), a team of scientists observed V404 Cyg with the Chandra X-ray Observatory, obtaining spectra of the black hole during its outbursts. The black hole flared so brightly during its activity that the team had to take precautions to protect the CCDs in their detector from radiation damage! Now the group has released the first results from their analysis.Windy DiskThe primary surprise from V404 Cyg is its winds. Many stellar-mass black holes have outflows of mass, either in the form of directed jets emitted from their centers, or in the form of high-energy winds isotropically emitted from their accretion disks. But V404

Introduction to General Relativity and Black Holes (5/5)

CERN Multimedia

CERN. Geneva

2001-01-01

Conceptual foundations of General Relativity (GR). Uniqueness of GR. Mathematical framework: tensor calculus, Riemannian geometry, connection, 'spin' connection, curvature, Cartan's form calculus. Hilbert-Einstein action, Einstein equations. Weak gravitational fields. Post Newtonian Approximation. Gravitanional Waves. Exact solutions. Killing vectors. Experimental tests. Black Holes: extensions of the Schwarzschild solution; Kerr-Newman holes; no-hair theorems; energtics of black holes; the membrane approach; quantum mechanics of black holes; Bekenstein entropy; Hawking temperature; black holes and string theory.

Introduction to General Relativity and Black Holes (3/5)

CERN Multimedia

CERN. Geneva

2001-01-01

Conceptual foundations of General Relativity (GR). Uniqueness of GR. Mathematical framework: tensor calculus, Riemannian geometry, connection, 'spin' connection, curvature, Cartan's form calculus. Hilbert-Einstein action, Einstein equations. Weak gravitational fields. Post Newtonian Approximation. Gravitanional Waves. Exact solutions. Killing vectors. Experimental tests. Black Holes: extensions of the Schwarzschild solution; Kerr-Newman holes; no-hair theorems; energtics of black holes; the membrane approach; quantum mechanics of black holes; Bekenstein entropy; Hawking temperature; black holes and string theory.

Introduction to General Relativity and Black Holes (1/5)

CERN Multimedia

CERN. Geneva

2001-01-01

Conceptual foundations of General Relativity (GR). Uniqueness of GR. Mathematical framework: tensor calculus, Riemannian geometry, connection, 'spin' connection, curvature, Cartan's form calculus. Hilbert-Einstein action, Einstein equations. Weak gravitational fields. Post Newtonian Approximation. Gravitanional Waves. Exact solutions. Killing vectors. Experimental tests. Black Holes: extensions of the Schwarzschild solution; Kerr-Newman holes; no-hair theorems; energtics of black holes; the membrane approach; quantum mechanics of black holes; Bekenstein entropy; Hawking temperature; black holes and string theory.

Introduction to General Relativity and Black Holes (2/5)

CERN Multimedia

CERN. Geneva

2001-01-01

Conceptual foundations of General Relativity (GR). Uniqueness of GR. Mathematical framework: tensor calculus, Riemannian geometry, connection, 'spin' connection, curvature, Cartan's form calculus. Hilbert-Einstein action, Einstein equations. Weak gravitational fields. Post Newtonian Approximation. Gravitanional Waves. Exact solutions. Killing vectors. Experimental tests. Black Holes: extensions of the Schwarzschild solution; Kerr-Newman holes; no-hair theorems; energtics of black holes; the membrane approach; quantum mechanics of black holes; Bekenstein entropy; Hawking temperature; black holes and string theory.

Introduction to General Relativity and Black Holes (4/5)

CERN Multimedia

CERN. Geneva

2001-01-01

Conceptual foundations of General Relativity (GR). Uniqueness of GR. Mathematical framework: tensor calculus, Riemannian geometry, connection, 'spin' connection, curvature, Cartan's form calculus. Hilbert-Einstein action, Einstein equations. Weak gravitational fields. Post Newtonian Approximation. Gravitanional Waves. Exact solutions. Killing vectors. Experimental tests. Black Holes: extensions of the Schwarzschild solution; Kerr-Newman holes; no-hair theorems; energtics of black holes; the membrane approach; quantum mechanics of black holes; Bekenstein entropy; Hawking temperature; black holes and string theory.

76 FR 36150 - Notice of Inventory Completion: Florida Department of State/Division of Historical Resources...

Science.gov (United States)

2011-06-21

....A. Pound Human Identification Laboratory and Dr. John Krigbaum, University of Florida, Department of... described as a multi-component black earth midden deposit on a relict Everglades tree island, associated... to the Florida Department of State/Division of Historical Resources for identification pending...

Black Hole Interior in Quantum Gravity.

Science.gov (United States)

Nomura, Yasunori; Sanches, Fabio; Weinberg, Sean J

2015-05-22

We discuss the interior of a black hole in quantum gravity, in which black holes form and evaporate unitarily. The interior spacetime appears in the sense of complementarity because of special features revealed by the microscopic degrees of freedom when viewed from a semiclassical standpoint. The relation between quantum mechanics and the equivalence principle is subtle, but they are still consistent.

Theorizing black (African) transnational masculinities

OpenAIRE

Pasura, Dominic; Christou, Anastasia

2017-01-01

Just as masculinity is crucial in the construction of nationhood, masculinity is also significant in the making and unmaking of transnational communities. This article focuses on how black African men negotiate and perform respectable masculinity in transnational settings, such as the workplace, community, and family. Moving away from conceptualizations of black transnational forms of masculinities as in perpetual crisis and drawing on qualitative data collected from the members of the new Af...

An Historical Overview of the Political Status of Blacks in England, since 1945.

Science.gov (United States)

Lindsey, Lydia

1989-01-01

Argues that the present status of Blacks in England has been shaped by the changing nature of the Empire and Commonwealth, the declining British economy, and political underrepresentation, and that it reflects immigration restrictions and the British polity's refusal to acknowledge the effect of adverse racial, colonial, and political factors. (AF)

Young, Gifted, and Black: Promoting High Achievement among African-American Students.

Science.gov (United States)

Perry, Theresa; Steele, Claude; Hilliard, Asa G., III

In three linked but separate essays, this book explores how African-American students experience school in a society that has historically devalued their intellectual abilities. It calls for a new understanding of the unique obstacles black students face in American schools and points to a variety of educational practices that can mitigate those…

Binary pairs of supermassive black holes - Formation in merging galaxies

Energy Technology Data Exchange (ETDEWEB)

Valtaoja, L.; Valtonen, M.J.; Byrd, G.G. (Turku Univ. (Finland); Alabama Univ., Tuscaloosa (USA))

1989-08-01

A process in which supermassive binary blackholes are formed in nuclei of supergiant galaxies due to galaxy mergers is examined. There is growing evidence that mergers of galaxies are common and that supermassive black holes in center of galaxies are also common. Consequently, it is expected that binary black holes should arise in connection with galaxy mergers. The merger process in a galaxy modeled after M87 is considered. The capture probability of a companion is derived as a function of its mass. Assuming a correlation between the galaxy mass and the blackholes mass, the expected mass ratio in binary black holes is calculated. The binary black holes formed in this process are long lived, surviving longer than the Hubble time unless they are perturbed by black holes from successive mergers. The properties of these binaries agree with Gaskell's (1988) observational work on quasars and its interpretation in terms of binary black holes. 39 refs.

Massive Binary Black Holes in the Cosmic Landscape

Science.gov (United States)

Colpi, Monica; Dotti, Massimo

2011-02-01

Binary black holes occupy a special place in our quest for understanding the evolution of galaxies along cosmic history. If massive black holes grow at the center of (pre-)galactic structures that experience a sequence of merger episodes, then dual black holes form as inescapable outcome of galaxy assembly, and can in principle be detected as powerful dual quasars. But, if the black holes reach coalescence, during their inspiral inside the galaxy remnant, then they become the loudest sources of gravitational waves ever in the universe. The Laser Interferometer Space Antenna is being developed to reveal these waves that carry information on the mass and spin of these binary black holes out to very large look-back times. Nature seems to provide a pathway for the formation of these exotic binaries, and a number of key questions need to be addressed: How do massive black holes pair in a merger? Depending on the properties of the underlying galaxies, do black holes always form a close Keplerian binary? If a binary forms, does hardening proceed down to the domain controlled by gravitational wave back reaction? What is the role played by gas and/or stars in braking the black holes, and on which timescale does coalescence occur? Can the black holes accrete on flight and shine during their pathway to coalescence? After outlining key observational facts on dual/binary black holes, we review the progress made in tracing their dynamics in the habitat of a gas-rich merger down to the smallest scales ever probed with the help of powerful numerical simulations. N-Body/hydrodynamical codes have proven to be vital tools for studying their evolution, and progress in this field is expected to grow rapidly in the effort to describe, in full realism, the physics of stars and gas around the black holes, starting from the cosmological large scale of a merger. If detected in the new window provided by the upcoming gravitational wave experiments, binary black holes will provide a deep view

Super-horizon primordial black holes

International Nuclear Information System (INIS)

Harada, Tomohiro; Carr, B.J.

2005-01-01

We discuss a new class of solutions to the Einstein equations which describe a primordial black hole (PBH) in a flat Friedmann background. Such solutions arise if a Schwarzschild black hole is patched onto a Friedmann background via a transition region. They are possible providing the black hole event horizon is larger than the cosmological apparent horizon. Such solutions have a number of strange features. In particular, one has to define the black hole and cosmological horizons carefully and one then finds that the mass contained within the black hole event horizon decreases when the black hole is larger than the Friedmann cosmological apparent horizon, although its area always increases. These solutions involve two distinct future null infinities and are interpreted as the conversion of a white hole into a black hole. Although such solutions may not form from gravitational collapse in the same way as standard PBHs, there is nothing unphysical about them, since all energy and causality conditions are satisfied. Their conformal diagram is a natural amalgamation of the Kruskal diagram for the extended Schwarzschild solution and the conformal diagram for a black hole in a flat Friedmann background. In this paper, such solutions are obtained numerically for a spherically symmetric universe containing a massless scalar field, but it is likely that they exist for more general matter fields and less symmetric systems

The renaissance of black phosphorus.

Science.gov (United States)

Ling, Xi; Wang, Han; Huang, Shengxi; Xia, Fengnian; Dresselhaus, Mildred S

2015-04-14

One hundred years after its first successful synthesis in the bulk form in 1914, black phosphorus (black P) was recently rediscovered from the perspective of a 2D layered material, attracting tremendous interest from condensed matter physicists, chemists, semiconductor device engineers, and material scientists. Similar to graphite and transition metal dichalcogenides (TMDs), black P has a layered structure but with a unique puckered single-layer geometry. Because the direct electronic band gap of thin film black P can be varied from 0.3 eV to around 2 eV, depending on its film thickness, and because of its high carrier mobility and anisotropic in-plane properties, black P is promising for novel applications in nanoelectronics and nanophotonics different from graphene and TMDs. Black P as a nanomaterial has already attracted much attention from researchers within the past year. Here, we offer our opinions on this emerging material with the goal of motivating and inspiring fellow researchers in the 2D materials community and the broad readership of PNAS to discuss and contribute to this exciting new field. We also give our perspectives on future 2D and thin film black P research directions, aiming to assist researchers coming from a variety of disciplines who are desirous of working in this exciting research field.

Black-Litterman model on non-normal stock return (Case study four banks at LQ-45 stock index)

Science.gov (United States)

Mahrivandi, Rizki; Noviyanti, Lienda; Setyanto, Gatot Riwi

2017-03-01

The formation of the optimal portfolio is a method that can help investors to minimize risks and optimize profitability. One model for the optimal portfolio is a Black-Litterman (BL) model. BL model can incorporate an element of historical data and the views of investors to form a new prediction about the return of the portfolio as a basis for preparing the asset weighting models. BL model has two fundamental problems, the assumption of normality and estimation parameters on the market Bayesian prior framework that does not from a normal distribution. This study provides an alternative solution where the modelling of the BL model stock returns and investor views from non-normal distribution.

Teaching Speech Communication in a Black College: Does Technology Make a Difference?

Science.gov (United States)

Nwadike, Fellina O.; Ekeanyanwu, Nnamdi T.

2011-01-01

Teaching a speech communication course in typical HBCUs (historically black colleges and universities) comes with many issues, because the application of technology in some minority institutions differs. The levels of acceptability as well as affordability are also core issues that affect application. Using technology in the classroom means many…

Aharonov–Bohm protection of black hole's baryon/skyrmion hair

Directory of Open Access Journals (Sweden)

Gia Dvali

2017-05-01

Full Text Available The baryon/skyrmion correspondence implies that the baryon number is encoded into a topological surface integral. Under certain conditions that we clarify, this surface integral can be measured by an asymptotic observer in form of an Aharonov–Bohm phase-shift in an experiment in which the skyrmion passes through a loop of a probe string. In such a setup the baryon/skyrmion number must be respected by black holes, despite the fact that it produces no long-range classical field. If initially swallowed by a black hole, the baryon number must resurface in form of a classical skyrmion hair, after the black hole evaporates below a certain critical size. Needless to say, the respect of the baryon number by black holes is expected to have potentially-interesting astrophysical consequences.

Sizes of Black Holes Throughout the Universe

Science.gov (United States)

Kohler, Susanna

2018-05-01

What is the distribution of sizes of black holes in our universe? Can black holes of any mass exist, or are there gaps in their possible sizes? The shape of this black-hole mass function has been debated for decades and the dawn of gravitational-wave astronomy has only spurred further questions.Mind the GapsThe starting point for the black-hole mass function lies in the initial mass function (IMF) for stellar black holes the beginning size distribution of black holes after they are born from stars. Instead of allowing for the formation of stellar black holes of any mass, theoretical models propose two gaps in the black-hole IMF:An upper mass gap at 50130 solar masses, due to the fact that stellar progenitors of black holes in this mass range are destroyed by pair-instability supernovae.A lower mass gap below 5 solar masses, which is argued to arise naturally from the mechanics of supernova explosions.Missing black-hole (BH) formation channels due to the existence of the lower gap (LG) and the upper gap (UG) in the initial mass function. a) The number of BHs at all scales are lowered because no BH can merge with BHs in the LG to form a larger BH. b) The missing channel responsible for the break at 10 solar masses, resulting from the LG. c) The missing channel responsible for the break at 60 solar masses, due to the interaction between the LG and the UG. [Christian et al. 2018]We can estimate the IMF for black holes by scaling a typical IMF for stars and then adding in these theorized gaps. But is this initial distribution of black-hole masses the same as the distribution that we observe in the universe today?The Influence of MergersBased on recent events, the answer appears to be no! Since the first detections of gravitational waves in September 2015, we now know that black holes can merge to form bigger black holes. An initial distribution of black-hole masses must therefore evolve over time, as mergers cause the depletion of low-mass black holes and an increase in

To Address Suffering That the Majority Can't See: Lessons from Black Women's Leadership in the Workplace

Science.gov (United States)

Dillard, Cynthia B.

2016-01-01

This chapter explores how both historically and in contemporary times of escalating violence against our bodies, minds, and spirits worldwide, Black women lead, love, and live within contexts of suffering.

Crossing Boundaries: Exploring Black Middle and Upper Class Preservice Teachers' Perceptions of Teaching and Learning in High Poverty Urban Schools

Science.gov (United States)

Lewis, Andrea D.

2012-01-01

The intent of this study was to explore the perceptions of Black middle and upper class preservice teachers as they relate to teaching and learning in high poverty urban schools. Participants included 11 senior early childhood education preservice teachers at a historically Black college in the southeast region of the United States. The study was…

On algebraically special perturbations of black holes

International Nuclear Information System (INIS)

Chandrasekhar, S.

1984-01-01

Algebraically special perturbations of black holes excite gravitational waves that are either purely ingoing or purely outgoing. Solutions, appropriate to such perturbations of the Kerr, the Schwarzschild, and the Reissner-Nordstroem black-holes, are obtained in explicit forms by different methods. The different methods illustrate the remarkable inner relations among different facets of the mathematical theory. In the context of the Kerr black-hole they derive from the different ways in which the explicit value of the Starobinsky constant emerges, and in the context of the Schwarzschild and the Reissner-Nordstroem black-holes they derive from the potential barriers surrounding them belonging to a special class. (author)

Glory scattering by black holes

International Nuclear Information System (INIS)

Matzner, R.A.; DeWitte-Morette, C.; Nelson, B.; Zhang, T.

1985-01-01

We present a physically motivated derivation of the JWKB backward glory-scattering cross section of massless waves by Schwarzschild black holes. The angular dependence of the cross section is identical with the one derived by path integration, namely, dsigma/dΩ = 4π 2 lambda -1 B/sub g/ 2 (dB mWπ, where lambda is the wavelength, B(theta) is the inverse of the classical deflection function CTHETA(B), B/sub g/ is the glory impact parameter, s is the helicity of the scattered wave, and J/sub 2s/ is the Bessel function of order 2s. The glory rings formed by scalar waves are bright at the center; those formed by polarized waves are dark at the center. For scattering of massless particles by a spherical black hole of mass M, B(theta)/Mapprox.3 √3 + 3.48 exp(-theta), theta > owigπ. The numerical values of dsigma/dΩ for this deflection function are found to agree with earlier computer calculations of glory cross sections from black holes

Formation of black hole and emission of gravitational waves.

Science.gov (United States)

Nakamura, Takashi

2006-12-01

Numerical simulations were performed for the formation process of rotating black holes. It is suggested that Kerr black holes are formed for wide ranges of initial parameters. The nature of gravitational waves from a test particle falling into a Kerr black hole as well as the development of 3D numerical relativity for the coalescing binary neutron stars are discussed.

Black branes and black strings in the astrophysical and cosmological context

Science.gov (United States)

Akarsu, Özgür; Chopovsky, Alexey; Zhuk, Alexander

2018-03-01

We consider Kaluza-Klein models where internal spaces are compact flat or curved Einstein spaces. This background is perturbed by a compact gravitating body with the dust-like equation of state (EoS) in the external/our space and an arbitrary EoS parameter Ω in the internal space. Without imposing any restrictions on the form of the perturbed metric and the distribution of the perturbed energy densities, we perform the general analysis of the Einstein and conservation equations in the weak-field limit. All conclusions follow from this analysis. For example, we demonstrate that the perturbed model is static and perturbed metric preserves the block-diagonal form. In a particular case Ω = - 1 / 2, the found solution corresponds to the weak-field limit of the black strings/branes. The black strings/branes are compact gravitating objects which have the topology (four-dimensional Schwarzschild spacetime) × (d-dimensional internal space) with d ≥ 1. We present the arguments in favour of these objects. First, they satisfy the gravitational tests for the parameterized post-Newtonian parameter γ at the same level of accuracy as General Relativity. Second, they are preferable from the thermodynamical point of view. Third, averaging over the Universe, they do not destroy the stabilization of the internal space. These are the astrophysical and cosmological aspects of the black strings/branes.

Quasistationary solutions of scalar fields around accreting black holes

Science.gov (United States)

Sanchis-Gual, Nicolas; Degollado, Juan Carlos; Izquierdo, Paula; Font, José A.; Montero, Pedro J.

2016-08-01

Massive scalar fields can form long-lived configurations around black holes. These configurations, dubbed quasibound states, have been studied both in the linear and nonlinear regimes. In this paper, we show that quasibound states can form in a dynamical scenario in which the mass of the black hole grows significantly due to the capture of infalling matter. We solve the Klein-Gordon equation numerically in spherical symmetry, mimicking the evolution of the spacetime through a sequence of analytic Schwarzschild black hole solutions of increasing mass. It is found that the frequency of oscillation of the quasibound states decreases as the mass of the black hole increases. In addition, accretion leads to an increase of the exponential decay of the scalar field energy. We compare the black hole mass growth rates used in our study with estimates from observational surveys and extrapolate our results to values of the scalar field masses consistent with models that propose scalar fields as dark matter in the universe. We show that, even for unrealistically large mass accretion rates, quasibound states around accreting black holes can survive for cosmological time scales. Our results provide further support to the intriguing possibility of the existence of dark matter halos based on (ultralight) scalar fields surrounding supermassive black holes in galactic centers.

Combustion-derived substances in deep basins of Puget Sound: Historical inputs from fossil fuel and biomass combustion

International Nuclear Information System (INIS)

Kuo, Li-Jung; Louchouarn, Patrick; Herbert, Bruce E.; Brandenberger, Jill M.; Wade, Terry L.; Crecelius, Eric

2011-01-01

Reconstructions of 250 years historical inputs of two distinct types of black carbon (soot/graphitic black carbon (GBC) and char-BC) were conducted on sediment cores from two basins of the Puget Sound, WA. Signatures of polycyclic aromatic hydrocarbons (PAHs) were also used to support the historical reconstructions of BC to this system. Down-core maxima in GBC and combustion-derived PAHs occurred in the 1940s in the cores from the Puget Sound Main Basin, whereas in Hood Canal such peak was observed in the 1970s, showing basin-specific differences in inputs of combustion byproducts. This system showed relatively higher inputs from softwood combustion than the northeastern U.S. The historical variations in char-BC concentrations were consistent with shifts in climate indices, suggesting an influence of climate oscillations on wildfire events. Environmental loading of combustion byproducts thus appears as a complex function of urbanization, fuel usage, combustion technology, environmental policies, and climate conditions. - Research highlights: → We reconstructed the historical inputs of GBC and char-BC in Puget Sound, WA, USA. → Temporal trend of GBC was linked to human activities (urbanization, fuel usage). → Temporal trend of char-BC was more likely driven by regional climate oscillations. → Historical trends of combustion byproducts show the geographical heterogeneities. - Temporal trend of GBC was directly linked to human activities, while the input of char-BC in Puget Sound was more likely driven by regional climate oscillations.

The Longue Durée of Black Lives Matter.

Science.gov (United States)

Nelson, Alondra

2016-10-01

Black Lives Matter was first articulated just a few years ago, but it has been the leitmotif of antiracist struggles for generations. The Movement for Black Lives extends the work of previous movements that challenged forms of oppression that act on Black bodies with impunity. It should be understood in the context of Ida B. Wells' anti-lynching campaign, Fannie Lou Hamer's reproductive justice demands, and the Black Panther Party's health activism. The 50th anniversary of the Black Panther Party is an occasion to recall that its work confronted the callous neglect and the corporeal surveillance and abuse of poor Black communities. Similar demands have been the centrifugal force of social movements that for centuries have refused to have Black lives cast beyond the human boundary.

Predictors of Grades for Black Americans in a Non-Calculus, Preprofessional Physics Sequence.

Science.gov (United States)

Vincent, Harold A.; And Others

Variables to predict grades in a noncalculus, preprofessional college physics course at Xavier University of Louisiana, a historically-black institution, were identified using linear regression. The two-semester, noncalculus physics course emphasizes the application of physics in the health professions. The study population consisted of 123…

Feedback Limits to Maximum Seed Masses of Black Holes

International Nuclear Information System (INIS)

Pacucci, Fabio; Natarajan, Priyamvada; Ferrara, Andrea

2017-01-01

The most massive black holes observed in the universe weigh up to ∼10 10 M ⊙ , nearly independent of redshift. Reaching these final masses likely required copious accretion and several major mergers. Employing a dynamical approach that rests on the role played by a new, relevant physical scale—the transition radius—we provide a theoretical calculation of the maximum mass achievable by a black hole seed that forms in an isolated halo, one that scarcely merged. Incorporating effects at the transition radius and their impact on the evolution of accretion in isolated halos, we are able to obtain new limits for permitted growth. We find that large black hole seeds ( M • ≳ 10 4 M ⊙ ) hosted in small isolated halos ( M h ≲ 10 9 M ⊙ ) accreting with relatively small radiative efficiencies ( ϵ ≲ 0.1) grow optimally in these circumstances. Moreover, we show that the standard M • – σ relation observed at z ∼ 0 cannot be established in isolated halos at high- z , but requires the occurrence of mergers. Since the average limiting mass of black holes formed at z ≳ 10 is in the range 10 4–6 M ⊙ , we expect to observe them in local galaxies as intermediate-mass black holes, when hosted in the rare halos that experienced only minor or no merging events. Such ancient black holes, formed in isolation with subsequent scant growth, could survive, almost unchanged, until present.

Characterization of microorganisms isolated from the black dirt of toilet bowls and componential analysis of the black dirt.

Science.gov (United States)

Mori, Miho; Nagata, Yusuke; Niizeki, Kazuma; Gomi, Mitsuhiro; Sakagami, Yoshikazu

2014-01-01

We have previously conducted a microflora analysis and examined the biofilm-forming activity of bacteria isolated from toilet bowl biofilms. In the present investigation, to reveal the strain involved in the formation of black dirt in toilet bowls, we performed a microflora analysis of the bacteria and fungi isolated from the black dirt of toilet bowls at ten homes. Among samples from different isolation sites and sampling seasons, although a similar tendency was not seen in bacterial microflora, Exophiala sp. was detected in the fungal microflora from all samples of black dirt except for one, and constituted the major presence. By scanning electron microscope (SEM) analysis of the formed black dirt, SEM image at × 1,000 and × 5,000 magnification showed objects like hyphae and many bacteria adhering to them, respectively. Micro fourier transform infrared spectroscopy (micro FT-IR) and SEM with X-ray microanalysis (SEM-XMA) were used to investigate the components of black dirt. IR spectra of micro-FT-IR showed typical absorptions associated with amide compounds and protein, and the elements such as C, N, O, Na, Mg, Al, Si, P, S, K, and Ba were detected with SEM-XMA. These results showed that black dirt had living body ingredients. Furthermore, Exophiala sp. and Cladosporium sp. strains, which were observed at a high frequency, accumulated 2-hydroxyjuglone (2-HJ) and flaviolin as one of the intermediates in the melanin biosynthetic pathway by the addition of a melanin synthesis inhibitor (tricyclazole) at the time of cultivation. These results suggested strongly that the pigment of black dirt in toilet bowls was melanin produced by Exophiala sp. and Cladosporium sp. strains.

Distinguishing Between Formation Channels for Binary Black Holes with LISA

Science.gov (United States)

Breivik, Katelyn; Rodriguez, Carl L.; Larson, Shane L.; Kalogera, Vassiliki; Rasio, Frederic A.

2017-01-01

The recent detections of GW150914 and GW151226 imply an abundance of stellar-mass binary-black-hole mergers in the local universe. While ground-based gravitational-wave detectors are limited to observing the final moments before a binary merges, space-based detectors, such as the Laser Interferometer Space Antenna (LISA), can observe binaries at lower orbital frequencies where such systems may still encode information about their formation histories. In particular, the orbital eccentricity and mass of binary black holes in the LISA frequency band can be used together to discriminate between binaries formed in isolation in galactic fields and those formed in dense stellar environments such as globular clusters. In this letter, we explore the orbital eccentricity and mass of binary-black-hole populations as they evolve through the LISA frequency band. Overall we find that there are two distinct populations discernible by LISA. We show that up to ~90% of binaries formed either dynamically or in isolation have eccentricities measurable by LISA. Finally, we note how measured eccentricities of low-mass binary black holes evolved in isolation could provide detailed constraints on the physics of black-hole natal kicks and common-envelope evolution.

Selected problems of protecting and managing historical ruins in Poland

Directory of Open Access Journals (Sweden)

Anna Fortuna-Marek

2017-12-01

Full Text Available Historical ruins have long been the object of interest for the research –workers of various disciplines as well as the conservators of historical monuments. The main problem is the form of protection. The standard of protecting ruins in the so-called permanent ruin form was elaborated two centuries ago, however, it is still the subject of numerous discussions, conferences, scientific-research works. The main source of doubts as to the permanent ruin is its incompleteness,(deficiency illegibility and the highly restricted possibilities of making any use of it, whereas the contemporary protection of monuments assumes their accessibility and the widest possible use for contemporary functions. That is why the main issue in contemporary maintenance of historical ruins is to ensure them a proper management system. The problem of protecting historical ruins has universal character. In Poland it concerns the resources of about 200 historical ruins, first and foremost of the mediaeval castles. That is why the Polish conservator circles have intensified the works aiming at the solution of the problem through the organization of programs, projects and conferences. A highly estimated result of those efforts is a programmatic document entitled “The Protection Charter of Historical Ruins”. It comprises a set of rules that determine the form of maintenance of historical ruins. However, the issues of management, development and use of the historical ruins still await a solution.

Rotating dilaton black holes with hair

International Nuclear Information System (INIS)

Kleihaus, Burkhard; Kunz, Jutta; Navarro-Lerida, Francisco

2004-01-01

We consider stationary rotating black holes in SU(2) Einstein-Yang-Mills theory, coupled to a dilaton. The black holes possess nontrivial non-Abelian electric and magnetic fields outside their regular event horizon. While generic solutions carry no non-Abelian magnetic charge, but non-Abelian electric charge, the presence of the dilaton field allows also for rotating solutions with no non-Abelian charge at all. As a consequence, these special solutions do not exhibit the generic asymptotic noninteger power falloff of the non-Abelian gauge field functions. The rotating black hole solutions form sequences, characterized by the winding number n and the node number k of their gauge field functions, tending to embedded Abelian black holes. The stationary non-Abelian black hole solutions satisfy a mass formula, similar to the Smarr formula, where the dilaton charge enters instead of the magnetic charge. Introducing a topological charge, we conjecture that black hole solutions in SU(2) Einstein-Yang-Mills-dilaton theory are uniquely characterized by their mass, their angular momentum, their dilaton charge, their non-Abelian electric charge, and their topological charge

Black-hole driven winds

International Nuclear Information System (INIS)

Punsly, B.M.

1988-01-01

This dissertation is a study of the physical mechanism that allows a large scale magnetic field to torque a rapidly rotating, supermassive black hole. This is an interesting problem as it has been conjectured that rapidly rotating black holes are the central engines that power the observed extragalactic double radio sources. Axisymmetric solutions of the curved space-time version of Maxwell's equations in the vacuum do not torque black holes. Plasma must be introduced for the hole to mechanically couple to the field. The dynamical aspect of rotating black holes that couples the magnetic field to the hole is the following. A rotating black hole forces the external geometry of space-time to rotate (the dragging of inertial frames). Inside of the stationary limit surface, the ergosphere, all physical particle trajectories must appear to rotate in the same direction as the black hole as viewed by the stationary observers at asymptotic infinity. In the text, it is demonstrated how plasma that is created on field lines that thread both the ergosphere and the equatorial plane will be pulled by gravity toward the equator. By the aforementioned properties of the ergosphere, the disk must rotate. Consequently, the disk acts like a unipolar generator. It drives a global current system that supports the toroidal magnetic field in an outgoing, magnetically dominated wind. This wind carries energy (mainly in the form of Poynting flux) and angular momentum towards infinity. The spin down of the black hole is the ultimate source of this energy and angular momentum flux

Gayl Jones’s Corregidora and Song For Anninho: Historical Revision, Female Diaspora, and Music

Directory of Open Access Journals (Sweden)

María Rocío Cobo Piñero

2014-12-01

Full Text Available http://dx.doi.org/10.5007/2175-8026.2014n67p37 In this article I analyze how black music may be used to (reinterpret the legacy of slavery in Gayl Jones’s literary works Corregidora (1975 and Song for Anninho (1981. I argue that female Classic Blues from the 1920s functions as a testimony of resistance and as a means to recount the stories featured in these two texts. The U.S. black author uses the cadences, themes, and tropes of the blues in order to decode female versions of the black diaspora in the Americas. In addition, by setting her literary work in Brazil, Jones establishes an inter-American dialogue and imagines polyphonic and syncretic spaces where the blues is the model for historical revision. Inscribing my study within the theoretical frame of black feminist cultural studies, I emphasize the importance of the first person enunciative voice in female blues, as well as in the texts selected.

Understanding the fate of merging supermassive black holes

International Nuclear Information System (INIS)

Campanelli, Manuela

2005-01-01

Understanding the fate of merging supermassive black holes in galactic mergers, and the gravitational wave emission from this process, are important LISA science goals. To this end, we present results from numerical relativity simulations of binary black hole mergers using the so-called Lazarus approach to model gravitational radiation from these events. In particular, we focus here on some recent calculations of the final spin and recoil velocity of the remnant hole formed at the end of a binary black hole merger process, which may constrain the growth history of massive black holes at the core of galaxies and globular clusters

Black hole radiation in the brane world and the recoil effect

International Nuclear Information System (INIS)

Frolov, Valeri; Stojkovic, Dejan

2002-01-01

A black hole attached to a brane in a higher-dimensional space emitting quanta into the bulk may leave the brane as a result of a recoil. We study this effect. We consider black holes which have a size much smaller than the characteristic size of extra dimensions. Such a black hole can be effectively described as a massive particle with internal degrees of freedom. We consider an interaction of such particles with a scalar massless field and prove that for a special choice of the coupling constant describing the transition of the particle to a state with smaller mass the probability of massless quanta emission takes the form identical to the probability of the black hole emission. Using this model we calculate the probability for a black hole to leave the brane and study its properties. The discussed recoil effect implies that, for black holes which might be created in the interaction of high energy particles in colliders, the thermal emission of the formed black hole could be terminated and the energy nonconservation can be observed in brane experiments

Virtual Black Holes and Space-Time Structure

Science.gov (United States)

't Hooft, Gerard

2018-01-01

In the standard formalism of quantum gravity, black holes appear to form statistical distributions of quantum states. Now, however, we can present a theory that yields pure quantum states. It shows how particles entering a black hole can generate firewalls, which however can be removed, replacing them by the `footprints' they produce in the out-going particles. This procedure can preserve the quantum information stored inside and around the black hole. We then focus on a subtle but unavoidable modification of the topology of the Schwarzschild metric: antipodal identification of points on the horizon. If it is true that vacuum fluctuations include virtual black holes, then the structure of space-time is radically different from what is usually thought.

Hydrodynamics and Elasticity of Charged Black Branes

DEFF Research Database (Denmark)

Gath, Jakob

We consider long-wavelength perturbations of charged black branes to first order in a uidelastic derivative expansion. At first order the perturbations decouple and we treat the hydrodynamic and elastic perturbations separately. To put the results in a broader perspective, we present the rst...... as a seed solution, we obtain a class of charged black brane geometries carrying smeared Maxwell charge in Einstein-Maxwell-dilaton theory. In the specific case of ten-dimensional space-time we furthermore use T-duality to generate bent black branes with higher-form charge, including smeared D...

Depilating Global Charge From Thermal Black Holes

CERN Document Server

March-Russell, John David; March-Russell, John; Wilczek, Frank

2001-01-01

At a formal level, there appears to be no difficulty involved in introducing a chemical potential for a globally conserved quantum number into the partition function for space-time including a black hole. Were this possible, however, it would provide a form of black hole hair, and contradict the idea that global quantum numbers are violated in black hole evaporation. We demonstrate dynamical mechanisms that negate the formal procedure, both for topological charge (Skyrmions) and complex scalar-field charge. Skyrmions collapse to the horizon; scalar-field charge fluctuates uncontrollably.

Looking for the invisible universe - Black matter, black energy, black holes

International Nuclear Information System (INIS)

Elbaz, David

2016-01-01

As the discovery of the expansion of the universe and of black holes put the study of cosmology into question again because it now refers to invisible things such as black holes, black energy and black matter, the author proposes an other view on the universe within such a context. He first discusses these three enigmas of black matter, black energy and black holes. In a second part, he addresses, discusses and comments five illusions: the Uranian illusion (questions of the existence of an anti-world, of black matter temperature), the Mercurian illusion (quantum gravity, the string theory), the Martian illusion (a patchwork universe, the illusion of the infinite), the cosmic Maya (the John Wheeler's cup, the holographic universe), and the narcissistic illusion

Two stellar-mass black holes in the globular cluster M22.

Science.gov (United States)

Strader, Jay; Chomiuk, Laura; Maccarone, Thomas J; Miller-Jones, James C A; Seth, Anil C

2012-10-04

Hundreds of stellar-mass black holes probably form in a typical globular star cluster, with all but one predicted to be ejected through dynamical interactions. Some observational support for this idea is provided by the lack of X-ray-emitting binary stars comprising one black hole and one other star ('black-hole/X-ray binaries') in Milky Way globular clusters, even though many neutron-star/X-ray binaries are known. Although a few black holes have been seen in globular clusters around other galaxies, the masses of these cannot be determined, and some may be intermediate-mass black holes that form through exotic mechanisms. Here we report the presence of two flat-spectrum radio sources in the Milky Way globular cluster M22, and we argue that these objects are black holes of stellar mass (each ∼10-20 times more massive than the Sun) that are accreting matter. We find a high ratio of radio-to-X-ray flux for these black holes, consistent with the larger predicted masses of black holes in globular clusters compared to those outside. The identification of two black holes in one cluster shows that ejection of black holes is not as efficient as predicted by most models, and we argue that M22 may contain a total population of ∼5-100 black holes. The large core radius of M22 could arise from heating produced by the black holes.

Kaleidoscoping the Simple: Graphic Representations and Form in The Black Key’s "Lonely Boy"

Directory of Open Access Journals (Sweden)

Alessandro Bratus

2016-02-01

Full Text Available Formal definition of songs in popular music is often thought of as a simple operation of detecting the juxtaposition of sections such as verse, chorus, bridge, special and so on. In the first part of my paper I propose a different theoretical outlook on the problem of form, showing how it can be fruitfully approached if considered as a system of four underlying principles in a dynamic equilibrium: repetition, superimposition, modularity and stratification. In the second part of the paper a quick survey on the specific case study of The Black Key’s "Lonely boy" shows these different forces at work. The relationships between the various formal principles can be best understood through different sorts of graphic representational strategies, gaining different perspectives on the same object. This multiplication of viable vantage points presents a twofold analytical relevance: it opens the interpretation of the structural traits of cultural objects as part of a complex semiotic system, at same time helping reconstruct a network of meanings which represents their own unique features.

Science self-efficacy of African Americans enrolled in freshman level physical science courses in two historically black institutions

Science.gov (United States)

Prihoda, Belinda Ann

2011-12-01

Science education must be a priority for citizens to function and be productive in a global, technological society. African Americans receive fewer science degrees in proportion to the Caucasian population. The primary purposes of this study were to determine the difference between the pretest and posttest science self-efficacy scores of African-American nonscience majors, the difference between the pretest and posttest science self-efficacy scores of African-American science majors, the relationship between science self-efficacy and course grade, the relationship between gender and science self-efficacy score, and the relationship between science self-efficacy score and course withdrawal. This study utilized a Likert survey instrument. All participants were enrolled in freshman level courses in the physical sciences at a historically black institution: a college or university. Participants completed the pretest survey within two weeks after the 12th class day of the semester. Initially, 458 participants completed the pretest survey. The posttest was administered within two weeks before the final exam. Only 245 participants completed the posttest survey. Results indicate that there is a difference in science self-efficacy of science majors and nonscience majors. There was no significant difference between the pretest and posttest science self-efficacy scores of African-American science majors and nonscience majors. There was no significant relationship between science self-efficacy and course grade, gender and science self-efficacy score, and course withdrawal and science self-efficacy score.

Black Tourism in the United States of America

OpenAIRE

Solgaard, Emilie Olivia Dam; Kovacova, Nikola; Munk, Jakob; Chinan, Ovidiu; Krin, Riccardo

2013-01-01

This study investigates elements of black tourism, and visitor motivations. Our goal is to reach an understanding of visitor motivations, and how dark sites and their symbols may have an impact on its visitors. Through theories of semiotics, classification, and historical processes, we have reached a satisfying conclusion, but theoretical data was not our only tool to reach this conclusion. Relevant research questions, study cases and methods played a big role in our project report. We used t...

Race, Housing, and the Federal Government: Black Lives on the Margins of the American Dream

Directory of Open Access Journals (Sweden)

Richard Hughes

2016-11-01

Full Text Available As historians have increasingly explored the complex historical relationship between race, class, and institutions such as the federal government in shaping contemporary American society, historical sources such as the Federal Housing Association’s Underwriting Manual (1938 provide provocative opportunities for teaching. Brief excerpts from the Manual are a small window through which to examine the underappreciated role of the U.S. federal government in creating and sustaining a racialized version of the American Dream. The result is an opportunity to equip students, as citizens, with the historical thinking skills and sources to examine the enduring historical arc of racial injustice and resistance in the United States that serves as the foundation for the Black Lives Matter movement.

Interior structure of rotating black holes. III. Charged black holes

International Nuclear Information System (INIS)

Hamilton, Andrew J. S.

2011-01-01

This paper extends to the case of charged rotating black holes the conformally stationary, axisymmetric, conformally separable solutions presented for uncharged rotating black holes in a companion paper. In the present paper, the collisionless fluid accreted by the black hole may be charged. The charge of the black hole is determined self-consistently by the charge accretion rate. As in the uncharged case, hyper-relativistic counterstreaming between ingoing and outgoing streams drives inflation at (just above) the inner horizon, followed by collapse. If both ingoing and outgoing streams are charged, then conformal separability holds during early inflation, but fails as inflation develops. If conformal separability is imposed throughout inflation and collapse, then only one of the ingoing and outgoing streams can be charged: the other must be neutral. Conformal separability prescribes a hierarchy of boundary conditions on the ingoing and outgoing streams incident on the inner horizon. The dominant radial boundary conditions require that the incident ingoing and outgoing number densities be uniform with latitude, but the charge per particle must vary with latitude such that the incident charge densities vary in proportion to the radial electric field. The subdominant angular boundary conditions require specific forms of the incident number- and charge-weighted angular motions. If the streams fall freely from outside the horizon, then the prescribed angular conditions can be achieved by the charged stream, but not by the neutral stream. Thus, as in the case of an uncharged black hole, the neutral stream must be considered to be delivered ad hoc to just above the inner horizon.

Magnetic charge, black holes, and cosmic censorship

International Nuclear Information System (INIS)

Hiscock, W.H.

1981-01-01

The possibility of converting a Reissner-Nordstroem black hole into a naked singularity by means of test particle accretion is considered. The dually charged Reissner-Nordstroem metric describes a black hole only when M 2 >Q 2 +P 2 . The test particle equations of motion are shown to allow test particles with arbitrarily large magnetic charge/mass ratios to fall radially into electrically charged black holes. To determine the nature of the final state (black hole or naked singularity) an exact solution of Einstein's equations representing a spherical shell of magnetically charged dust falling into an electrically charged black hole is studied. Naked singularities are never formed so long as the weak energy condition is obeyed by the infalling matter. The differences between the spherical shell model and an infalling point test particle are examined and discussed

Black Skin, White Pioneer: Non-Traditional Casting in an Israeli School Pageant

Science.gov (United States)

Shem-Tov, Naphtaly

2013-01-01

The casting of a black Ethiopian Jewish girl to play a white Zionist pioneer character in an Israeli school pageant causes feelings of discomfort among the teachers, especially the vice-principal. The vice-principal uses theatrical and historical reasons to justify her opposition to the casting which can actually be perceived as new/colour-blind…

The Formation and Evolution of the First Massive Black Holes

OpenAIRE

Haiman, Zoltan; Quataert, Eliot

2004-01-01

The first massive astrophysical black holes likely formed at high redshifts (z>10) at the centers of low mass (~10^6 Msun) dark matter concentrations. These black holes grow by mergers and gas accretion, evolve into the population of bright quasars observed at lower redshifts, and eventually leave the supermassive black hole remnants that are ubiquitous at the centers of galaxies in the nearby universe. The astrophysical processes responsible for the formation of the earliest seed black holes...

Can superconducting cosmic strings piercing seed black holes generate supermassive black holes in the early universe?

Energy Technology Data Exchange (ETDEWEB)

Lake, Matthew J. [The Institute for Fundamental Study, ' ' The Tah Poe Academia Institute' ' , Naresuan University, Phitsanulok (Thailand); Thailand Center of Excellence in Physics, Ministry of Education, Bangkok (Thailand); Harko, Tiberiu [Department of Physics, Babes-Bolyai University, Cluj-Napoca (Romania); Department of Mathematics, University College London (United Kingdom)

2017-10-15

The discovery of a large number of supermassive black holes (SMBH) at redshifts z > 6, when the Universe was only 900 million years old, raises the question of how such massive compact objects could form in a cosmologically short time interval. Each of the standard scenarios proposed, involving rapid accretion of seed black holes or black hole mergers, faces severe theoretical difficulties in explaining the short-time formation of supermassive objects. In this work we propose an alternative scenario for the formation of SMBH in the early Universe, in which energy transfer from superconducting cosmic strings piercing small seed black holes is the main physical process leading to rapid mass increase. As a toy model, the accretion rate of a seed black hole pierced by two antipodal strings carrying constant current is considered. Using an effective action approach, which phenomenologically incorporates a large class of superconducting string models, we estimate the minimum current required to form SMBH with masses of order M = 2 x 10{sup 9} M {sub CircleDot} by z = 7.085. This corresponds to the mass of the central black hole powering the quasar ULAS J112001.48+064124.3 and is taken as a test case scenario for early-epoch SMBH formation. For GUT scale strings, the required fractional increase in the string energy density, due to the presence of the current, is of order 10{sup -7}, so that their existence remains consistent with current observational bounds on the string tension. In addition, we consider an ''exotic'' scenario, in which an SMBH is generated when a small seed black hole is pierced by a higher-dimensional F-string, predicted by string theory. We find that both topological defect strings and fundamental strings are able to carry currents large enough to generate early-epoch SMBH via our proposed mechanism. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Will we observe black holes at the LHC?

International Nuclear Information System (INIS)

Cavaglia, Marco; Das, Saurya; Maartens, Roy

2003-01-01

The generalized uncertainty principle, motivated by string theory and non-commutative quantum mechanics, suggests significant modifications to the Hawking temperature and evaporation process of black holes. For extra-dimensional gravity with Planck scale O(TeV), this leads to important changes in the formation and detection of black holes at the large hadron collider. The number of particles produced in Hawking evaporation decreases substantially. The evaporation ends when the black-hole mass is Planck scale, leaving a remnant and a consequent missing energy of order TeV. Furthermore, the minimum energy for black-hole formation in collisions is increased, and could even be increased to such an extent that no black holes are formed at LHC energies. (letter to the editor)

Rural and historical tourism in Dobrugea

OpenAIRE

Sima, Elena

2014-01-01

By its geographical location, the rural area from Dobrudgea has a diversified tourism potential, provided by the contrasting natural environmental factors, ranging from the oldest to the youngest relief units, natural protected areas, balneary resources and cultural, historical, religious sites, as well as multicultural local customs and traditions of the rural area. This potential can be used under various forms in the rural area: cultural tourism, historical tourism, religious tourism, ecot...

Rural and historical tourism in Dobrogea

OpenAIRE

Sima, Elena

2014-01-01

By its geographical location, the rural area from Dobrudgea has a diversified tourism potential, provided by the contrasting natural environmental factors, ranging from the oldest to the youngest relief units, natural protected areas, balneary resources and cultural, historical, religious sites, as well as multicultural local customs and traditions of the rural area. This potential can be used under various forms in the rural area: cultural tourism, historical tourism, religious tourism, ecot...

Automorphic black holes as probes of extra dimensions

Energy Technology Data Exchange (ETDEWEB)

Cassella, Kayleigh, E-mail: kcassell@berkeley.edu [Department of Physics, Indiana University South Bend, 1700 Mishawaka Ave., South Bend, IN 46634 (United States); Schimmrigk, Rolf, E-mail: netahu@yahoo.com [Max-Planck-Institut fuer Physik, Foehringer Ring 6, 80805 Muenchen (Germany)

2012-05-11

Recent progress in the understanding of the statistical nature of black hole entropy shows that the counting functions in certain classes of models are determined by automorphic forms of higher rank. In this paper we combine these results with Langlands' reciprocity conjecture to view black holes as probes of the geometry of spacetime. This point of view can be applied in any framework leading to automorphic forms, independently of the degree of supersymmetry of the models. In the present work we focus on the class of Chaudhuri-Hockney-Lykken compactifications defined as quotients associated to Z{sub N} groups. We show that the black hole entropy of these CHL{sub N} models can be derived from elliptic motives, thereby providing the simplest possible geometric building blocks of the Siegel type entropy count.

Feedback Limits to Maximum Seed Masses of Black Holes

Energy Technology Data Exchange (ETDEWEB)

Pacucci, Fabio; Natarajan, Priyamvada [Department of Physics, Yale University, P.O. Box 208121, New Haven, CT 06520 (United States); Ferrara, Andrea [Scuola Normale Superiore, Piazza dei Cavalieri 7, I-56126 Pisa (Italy)

2017-02-01

The most massive black holes observed in the universe weigh up to ∼10{sup 10} M {sub ⊙}, nearly independent of redshift. Reaching these final masses likely required copious accretion and several major mergers. Employing a dynamical approach that rests on the role played by a new, relevant physical scale—the transition radius—we provide a theoretical calculation of the maximum mass achievable by a black hole seed that forms in an isolated halo, one that scarcely merged. Incorporating effects at the transition radius and their impact on the evolution of accretion in isolated halos, we are able to obtain new limits for permitted growth. We find that large black hole seeds ( M {sub •} ≳ 10{sup 4} M {sub ⊙}) hosted in small isolated halos ( M {sub h} ≲ 10{sup 9} M {sub ⊙}) accreting with relatively small radiative efficiencies ( ϵ ≲ 0.1) grow optimally in these circumstances. Moreover, we show that the standard M {sub •}– σ relation observed at z ∼ 0 cannot be established in isolated halos at high- z , but requires the occurrence of mergers. Since the average limiting mass of black holes formed at z ≳ 10 is in the range 10{sup 4–6} M {sub ⊙}, we expect to observe them in local galaxies as intermediate-mass black holes, when hosted in the rare halos that experienced only minor or no merging events. Such ancient black holes, formed in isolation with subsequent scant growth, could survive, almost unchanged, until present.

Staying in the Hood: Black Lesbian and Transgender Women and Identity Management in North Philadelphia.

Science.gov (United States)

Brooks, Siobhan

2016-12-01

The concept Don't Ask, Don't Tell regarding Black LGBT sexuality in Black communities has been an acceptable form of identity management for Black LGBT people. In other words, Black LGBT people are accepted as long as they are not vocal about their sexuality. However, this is changing with the issue of gay marriage, which is creating a space where Black LGBT people are more open about their gender identity and sexuality in heterosexual Black spaces. This new form of openness allows Black LGBT people to "stay in" their communities, as opposed to coming out. In this article I examine how Black LGBT women in North Philadelphia stay in their communities: being politically active regarding LGBT issues, disengaging from LGBT issues, passing, and educating straight Black people about issues affecting the Black LGBT community. I conclude with implications of staying in and intersectionality among Black heterosexual and LGBT women fighting for social change.

76 FR 375 - Notice of Availability: Notice of Funding Availability (NOFA) for Fiscal Year 2010; Historically...

Science.gov (United States)

2011-01-04

...: Notice of Funding Availability (NOFA) for Fiscal Year 2010; Historically Black Colleges and Universities... Fiscal Year 2010. This NOFA is governed by the information and instructions found in HUD's Fiscal Year 2010 Notice of Funding Availability (NOFA) Policy Requirements and General Section that HUD issued on...

Seasonal mercury concentrations and {delta}{sup 15}N and {delta}{sup 13}C values of benthic macroinvertebrates and sediments from a historically polluted estuary in south central Chile

Energy Technology Data Exchange (ETDEWEB)

Diaz-Jaramillo, Mauricio, E-mail: mdiazjaramillo@conicet.gov.ar [Aquatic Systems Research Unit, EULA Chile Environmental Sciences Centre, Universidad de Concepcion (Chile); Munoz, Claudia; Rudolph, Ignacio [Aquatic Systems Research Unit, EULA Chile Environmental Sciences Centre, Universidad de Concepcion (Chile); Servos, Mark [Department of Biology, University of Waterloo, ON (Canada); Barra, Ricardo [Aquatic Systems Research Unit, EULA Chile Environmental Sciences Centre, Universidad de Concepcion (Chile)

2013-01-01

The Lenga Estuary is one of the most industrialized sites in south central Chile where the historic operation of chlor-alkali plants resulted in large quantities of mercury (Hg) being deposited into the estuary. This historical contamination may still represent a risk to the biota in the estuary. To investigate this four macroinvertebrates, Neotrypaea uncinata (ghostshrimp), Elminius kingii (barnacle), Hemigrapsus crenulatus (shore crab) and Perinereis gualpensis (ragworm) were collected seasonally from three different sites in the Lenga Estuary and one in a reference estuary (Tubul Estuary), and analyzed for Hg and stable isotopes ({delta}{sup 15}N and {delta}{sup 13}C). Mercury concentrations in Lenga sediments ranged from 0.4 {+-} 0.1 to 13 {+-} 3 mg/kg, while those in Tubul sediments ranged from 0.02 {+-} 0.01 to 0.07 {+-} 0.09 mg/kg. Total Hg concentrations of invertebrates were significantly different between estuaries (p < 0.05), but not by species or season for each estuary (p > 0.05). In contrast, organic Hg concentrations were different by species and season with shore crab muscle tissues exhibiting the greatest percent difference. Site-specific relationships demonstrated that total Hg concentrations in ragworm best reflected the total Hg sediment mercury concentrations. Signatures of {delta}{sup 13}C were correlated to the organic Hg % rather than total Hg. This suggests that organic Hg concentrations in these species were related to the carbon sources. -- Highlights: Black-Right-Pointing-Pointer Hg in sediments and biota from Lenga Estuary were elevated compared to nearby estuary. Black-Right-Pointing-Pointer Invertebrates showed interspecific and seasonal differences in terms of organic Hg %. Black-Right-Pointing-Pointer Total Hg levels in the ragworm best reflect Hg sediment gradient in Lenga Estuary. Black-Right-Pointing-Pointer Interspecific variation in {delta}{sup 13}C signatures indicated different feeding modes. Black

Excluding black hole firewalls with extreme cosmic censorship

Energy Technology Data Exchange (ETDEWEB)

Page, Don N., E-mail: profdonpage@gmail.com [Department of Physics, 4-183 CCIS, University of Alberta, Edmonton, Alberta T6G 2E1 (Canada)

2014-06-01

The AMPS argument for black hole firewalls seems to arise not only from the assumption of local effective field theory outside the stretched horizon but also from an overcounting of internal black hole states that include states that are singular in the past. Here I propose to exclude such singular states by Extreme Cosmic Censorship (the conjectured principle that the universe is entirely nonsingular, except for transient singularities inside black and/or white holes). I argue that the remaining set of nonsingular realistic states do not have firewalls but yet preserve information in Hawking radiation from black holes that form from nonsingular initial states.

Excluding black hole firewalls with extreme cosmic censorship

International Nuclear Information System (INIS)

Page, Don N.

2014-01-01

The AMPS argument for black hole firewalls seems to arise not only from the assumption of local effective field theory outside the stretched horizon but also from an overcounting of internal black hole states that include states that are singular in the past. Here I propose to exclude such singular states by Extreme Cosmic Censorship (the conjectured principle that the universe is entirely nonsingular, except for transient singularities inside black and/or white holes). I argue that the remaining set of nonsingular realistic states do not have firewalls but yet preserve information in Hawking radiation from black holes that form from nonsingular initial states

Precocious Supermassive Black Holes Challenge Theories

Science.gov (United States)

2004-11-01

NASA's Chandra X-ray Observatory has obtained definitive evidence that a distant quasar formed less than a billion years after the Big Bang contains a fully-grown supermassive black hole generating energy at the rate of twenty trillion Suns. The existence of such massive black holes at this early epoch of the Universe challenges theories of the formation of galaxies and supermassive black holes. Astronomers Daniel Schwartz and Shanil Virani of the Harvard-Smithsonian Center for Astrophysics in Cambridge, MA observed the quasar, known as SDSSp J1306, which is 12.7 billion light years away. Since the Universe is estimated to be 13.7 billion years old, we see the quasar as it was a billion years after the Big Bang. They found that the distribution of X-rays with energy, or X-ray spectrum, is indistinguishable from that of nearby, older quasars. Likewise, the relative brightness at optical and X-ray wavelengths of SDSSp J1306 was similar to that of the nearby group of quasars. Optical observations suggest that the mass of the black hole is about a billion solar masses. Illustration of Quasar SDSSp J1306 Illustration of Quasar SDSSp J1306 Evidence of another early-epoch supermassive black hole was published previously by a team of scientists from the California Institute of Technology and the United Kingdom using the XMM-Newton X-ray satellite. They observed the quasar SDSSp J1030 at a distance of 12.8 billion light years and found essentially the same result for the X-ray spectrum as the Smithsonian scientists found for SDSSp J1306. Chandra's precise location and spectrum for SDSSp J1306 with nearly the same properties eliminate any lingering uncertainty that precocious supermassive black holes exist. "These two results seem to indicate that the way supermassive black holes produce X-rays has remained essentially the same from a very early date in the Universe," said Schwartz. "This implies that the central black hole engine in a massive galaxy was formed very soon

Old ages of two historical Romanian trees assessed by AMS radiocarbon dating

Energy Technology Data Exchange (ETDEWEB)

Patrut, Adrian, E-mail: apatrut@gmail.com [Babes-Bolyai University, Department of Chemistry, Arany Janos 11, 400028 Cluj-Napoca (Romania); Reden, Karl F. von [Woods Hole Oceanographic Institution, Department of Geology and Geophysics, NOSAMS Facility, 360 Woods Hole Rd., Mailstop 8, Woods Hole, MA 02543 (United States); Lowy, Daniel A. [FlexEl, LLC, 387 Technology Drive, College Park, MD 20742 (United States); Patrut, Roxana T. [Babes-Bolyai University, Department of Biology and Geology, Gh. Bilascu 44, 400015 Cluj-Napoca (Romania); Lucian Vaida, D. [Museum of Border Regiment Nasaud, Granicerilor 19, 425200 Nasaud (Romania); Margineanu, Dragos [Babes-Bolyai University, Department of Chemistry, Arany Janos 11, 400028 Cluj-Napoca (Romania)

2013-01-15

Two large Romanian poplars are considered to be associated with significant historical events of the past. In order to verify these claims, wood samples collected from the broken trunks of the two poplars were radiocarbon dated by AMS. The oldest radiocarbon dates were found to be 275 {+-} 20 bp for the black poplar of Mocod and 316 {+-} 22 bp for the gray poplar of Rafaila. These values correspond to calibrated ages of 365 {+-} 10 and 465 {+-} 25 years, respectively. The dating results indicate old ages for the two trees, i.e., 455 years for the Mocod poplar and 560 years for the Rafaila poplar. Such age values validate historical information on the two large Romanian trees.

Ineffective higher derivative black hole hair

Science.gov (United States)

Goldstein, Kevin; Mashiyane, James Junior

2018-01-01

Inspired by the possibility that the Schwarzschild black hole may not be the unique spherically symmetric vacuum solution to generalizations of general relativity, we consider black holes in pure fourth order higher derivative gravity treated as an effective theory. Such solutions may be of interest in addressing the issue of higher derivative hair or during the later stages of black hole evaporation. Non-Schwarzschild solutions have been studied but we have put earlier results on a firmer footing by finding a systematic asymptotic expansion for the black holes and matching them with known numerical solutions obtained by integrating out from the near-horizon region. These asymptotic expansions can be cast in the form of trans-series expansions which we conjecture will be a generic feature of non-Schwarzschild higher derivative black holes. Excitingly we find a new branch of solutions with lower free energy than the Schwarzschild solution, but as found in earlier work, solutions only seem to exist for black holes with large curvatures, meaning that one should not generically neglect even higher derivative corrections. This suggests that one effectively recovers the nonhair theorems in this context.

Divergent discourse between protests and counter-protests: #BlackLivesMatter and #AllLivesMatter.

Science.gov (United States)

Gallagher, Ryan J; Reagan, Andrew J; Danforth, Christopher M; Dodds, Peter Sheridan

2018-01-01

Since the shooting of Black teenager Michael Brown by White police officer Darren Wilson in Ferguson, Missouri, the protest hashtag #BlackLivesMatter has amplified critiques of extrajudicial killings of Black Americans. In response to #BlackLivesMatter, other Twitter users have adopted #AllLivesMatter, a counter-protest hashtag whose content argues that equal attention should be given to all lives regardless of race. Through a multi-level analysis of over 860,000 tweets, we study how these protests and counter-protests diverge by quantifying aspects of their discourse. We find that #AllLivesMatter facilitates opposition between #BlackLivesMatter and hashtags such as #PoliceLivesMatter and #BlueLivesMatter in such a way that historically echoes the tension between Black protesters and law enforcement. In addition, we show that a significant portion of #AllLivesMatter use stems from hijacking by #BlackLivesMatter advocates. Beyond simply injecting #AllLivesMatter with #BlackLivesMatter content, these hijackers use the hashtag to directly confront the counter-protest notion of "All lives matter." Our findings suggest that Black Lives Matter movement was able to grow, exhibit diverse conversations, and avoid derailment on social media by making discussion of counter-protest opinions a central topic of #AllLivesMatter, rather than the movement itself.

A Linear Algorithm for Black Scholes Economic Model

Directory of Open Access Journals (Sweden)

Dumitru FANACHE

2008-01-01

Full Text Available The pricing of options is a very important problem encountered in financial domain. The famous Black-Scholes model provides explicit closed form solution for the values of certain (European style call and put options. But for many other options, either there are no closed form solution, or if such closed form solutions exist, the formulas exhibiting them are complicated and difficult to evaluate accurately by conventional methods. The aim of this paper is to study the possibility of obtaining the numerical solution for the Black-Scholes equation in parallel, by means of several processors, using the finite difference method. A comparison between the complexity of the parallel algorithm and the serial one is given.

Risky sexual behaviors among sexually active first-year students matriculating at a historically Black college: Is a positive self-image an instigator?

Science.gov (United States)

Ellis, Walter L

2016-01-01

A sample of 498 sexually active first-year students matriculating at a historically Black college in North Carolina was used to determine correlates of risky sexual behaviors. In an Ordinary Least Squares regression, the self-esteem element "I take a positive attitude toward myself" (B = 1.12, p = .05), non-condom use because of partner issues (B = .53, p = .05) and being drunk or high (B = 1.20, p = .001), oral sex (B = 1.74, p = .001), anal sex (B = .61, p = .04), and bisexuality (B = .85, p = .03) all increased the number of these behaviors. Higher scores on the condom usage scale (B = -.38, p = .002) were found to decrease the number of risky sexual behaviors. Illicit drug use was an underpinning of the surprisingly positive relationship between positive self-image and risky sexual behaviors. It was concluded that school-based social workers, mental health care professionals, and community-based prevention providers can play a critical role in the training of peer facilitators, development, and supervision of peer-driven risk-reduction programs to address the complex interplay among self-esteem, sex, and substances.

Dynamical evolution of quasicircular binary black hole data

International Nuclear Information System (INIS)

Alcubierre, Miguel; Bruegmann, Bernd; Diener, Peter; Guzman, F. Siddhartha; Hawke, Ian; Hawley, Scott; Herrmann, Frank; Pollney, Denis; Thornburg, Jonathan; Koppitz, Michael; Seidel, Edward

2005-01-01

We study the fully nonlinear dynamical evolution of binary black hole data, whose orbital parameters are specified via the effective potential method for determining quasicircular orbits. The cases studied range from the Cook-Baumgarte innermost stable circular orbit (ISCO) to significantly beyond that separation. In all cases we find the black holes to coalesce (as determined by the appearance of a common apparent horizon) in less than half an orbital period. The results of the numerical simulations indicate that the initial holes are not actually in quasicircular orbits, but that they are in fact nearly plunging together. The dynamics of the final horizon are studied to determine physical parameters of the final black hole, such as its spin, mass, and oscillation frequency, revealing information about the inspiral process. We show that considerable resolution is required to extract accurate physical information from the final black hole formed in the merger process, and that the quasinormal modes of the final hole are strongly excited in the merger process. For the ISCO case, by comparing physical measurements of the final black hole formed to the initial data, we estimate that less than 3% of the total energy is radiated in the merger process

Measuring the spins of accreting black holes

International Nuclear Information System (INIS)

McClintock, Jeffrey E; Narayan, Ramesh; Gou, Lijun; Kulkarni, Akshay; Penna, Robert F; Steiner, James F; Davis, Shane W; Orosz, Jerome A; Remillard, Ronald A

2011-01-01

A typical galaxy is thought to contain tens of millions of stellar-mass black holes, the collapsed remnants of once massive stars, and a single nuclear supermassive black hole. Both classes of black holes accrete gas from their environments. The accreting gas forms a flattened orbiting structure known as an accretion disk. During the past several years, it has become possible to obtain measurements of the spins of the two classes of black holes by modeling the x-ray emission from their accretion disks. Two methods are employed, both of which depend upon identifying the inner radius of the accretion disk with the innermost stable circular orbit, whose radius depends only on the mass and spin of the black hole. In the Fe Kα method, which applies to both classes of black holes, one models the profile of the relativistically broadened iron line with a special focus on the gravitationally redshifted red wing of the line. In the continuum-fitting (CF) method, which has so far only been applied to stellar-mass black holes, one models the thermal x-ray continuum spectrum of the accretion disk. We discuss both methods, with a strong emphasis on the CF method and its application to stellar-mass black holes. Spin results for eight stellar-mass black holes are summarized. These data are used to argue that the high spins of at least some of these black holes are natal, and that the presence or absence of relativistic jets in accreting black holes is not entirely determined by the spin of the black hole.

7000 years of Emiliania huxleyi viruses in the Black Sea.

Science.gov (United States)

Coolen, Marco J L

2011-07-22

A 7000-year record of Coccolithovirus and its host, the calcifying haptophyte Emiliania huxleyi, was reconstructed on the basis of genetic signatures preserved in sediments underlying the Black Sea. The data show that the same virus and host populations can persist for centuries. Major changes in virus and host populations occurred during early sapropel deposition, ~5600 years ago, and throughout the formation of the coccolith-bearing sediments of Unit I during the past 2500 years, when the Black Sea experienced dramatic changes in hydrologic and nutrient regimes. Unit I saw a reoccurrence of the same host genotype thousands of years later in the presence of a different subset of viruses. Historical plankton virus populations can thus be included in paleoecological and paleoenvironmental studies.

The Intersection of Race and Gender in School Leadership for Three Black Female Principals

Science.gov (United States)

Reed, Latish Cherie

2012-01-01

Using four assumptions of Black feminism, this qualitative study describes the practice of three African-American female principals in predominantly African-American, urban high schools. First, in general, the principals seemed to understand their experiences as part of a larger historical context. Second, given the shared racial and gender…

Youth Historians in Harlem: An After-School Blueprint for History Engagement through the Historical Process

Science.gov (United States)

Goldenberg, Barry M.

2016-01-01

This manuscript, written with the educator in mind, describes the Youth Historians in Harlem (YHH) program, a twenty-week after-school history program that engaged urban students in history by immersing them in aspects of the historical process. Throughout the program, a group of Black male high school students were apprenticed as historical…

Gammaherpesvirus carrier status of black wildebeest (Connochaetes gnou in South Africa

Directory of Open Access Journals (Sweden)

J.A. Pretorius

2008-05-01

Full Text Available Malignant catarrhal fever (MCF is an economically important disease primarily of domestic cattle with a high case fatality rate. It is caused by either alcelaphine herpesvirus type 1 (AlHV-1 or ovine herpesvirus type 2 (OvHV-2. The major reservoir host of AlHV-1 is the blue wildebeest (Connochaetes taurinus, but it is generally accepted that the black wildebeest (Connochaetes gnou is also a reservoir host. No viral studies in the black wildebeest have been reported and the carrier status of black wildebeest has not been documented. Specimens were collected from several game farms and conservation areas in central South Africa representing the geographical area historically linked to the natural habitat of the black wildebeest. Specimens were obtained from 304 black wildebeest of different ages and sex, as well as 51 black wildebeest foetuses at different stages of gestation. Virus was isolated from a black wildebeest calf. Morphological features and antigenic characteristics suggested it to be a gammaherpesvirus closely related to AlHV-1. All serum samples tested positive with a competitive inhibition enzyme-linked immunosorbent assay (CI-ELISA for group-specific malignant catarrhal fever virus antibody. ASYBR Green real-time PCR assay was developed for the detection of gammaherpesviral DNA. Only 15.8 % of the animals tested positive with the real-time PCR assay whereas 90 % of the foetuses tested positive. This finding suggests that, unlike OvHV-2 infection in lambs in which the infection takes place after weaning, the virus in black wildebeest is mainly transmitted in utero or soon after birth. The results suggest that black wildebeest are latent carriers of a gammaherpesvirus similar or closely related to AlHV-1 present in blue wildebeest and that it is likely that all black wildebeest are persistently infected.

Thermodynamics of higher dimensional black holes

International Nuclear Information System (INIS)

Accetta, F.S.; Gleiser, M.

1986-05-01

We discuss the thermodynamics of higher dimensional black holes with particular emphasis on a new class of spinning black holes which, due to the increased number of Casimir invariants, have additional spin degrees of freedom. In suitable limits, analytic solutions in arbitrary dimensions are presented for their temperature, entropy, and specific heat. In 5 + 1 and 9 + 1 dimensions, more general forms for these quantities are given. It is shown that the specific heat for a higher dimensional black hole is negative definite if it has only one non-zero spin parameter, regardless of the value of this parameter. We also consider equilibrium configurations with both massless particles and massive string modes. 16 refs., 3 figs

Thermodynamics of higher dimensional black holes

Energy Technology Data Exchange (ETDEWEB)

Accetta, F.S.; Gleiser, M.

1986-05-01

We discuss the thermodynamics of higher dimensional black holes with particular emphasis on a new class of spinning black holes which, due to the increased number of Casimir invariants, have additional spin degrees of freedom. In suitable limits, analytic solutions in arbitrary dimensions are presented for their temperature, entropy, and specific heat. In 5 + 1 and 9 + 1 dimensions, more general forms for these quantities are given. It is shown that the specific heat for a higher dimensional black hole is negative definite if it has only one non-zero spin parameter, regardless of the value of this parameter. We also consider equilibrium configurations with both massless particles and massive string modes. 16 refs., 3 figs.

A VERY CLOSE BINARY BLACK HOLE IN A GIANT ELLIPTICAL GALAXY 3C 66B AND ITS BLACK HOLE MERGER

International Nuclear Information System (INIS)

Iguchi, Satoru; Okuda, Takeshi; Sudou, Hiroshi

2010-01-01

Recent observational results provide possible evidence that binary black holes (BBHs) exist in the center of giant galaxies and may merge to form a supermassive black hole in the process of their evolution. We first detected a periodic flux variation on a cycle of 93 ± 1 days from the 3 mm monitor observations of a giant elliptical galaxy 3C 66B for which an orbital motion with a period of 1.05 ± 0.03 yr had been already observed. The detected signal period being shorter than the orbital period can be explained by taking into consideration the Doppler-shifted modulation due to the orbital motion of a BBH. Assuming that the BBH has a circular orbit and that the jet axis is parallel to the binary angular momentum, our observational results demonstrate the presence of a very close BBH that has a binary orbit with an orbital period of 1.05 ± 0.03 yr, an orbital radius of (3.9 ± 1.0) x 10 -3 pc, an orbital separation of (6.1 +1.0 -0.9 ) x 10 -3 pc, a larger black hole mass of (1.2 +0.5 -0.2 ) x 10 9 M sun , and a smaller black hole mass of (7.0 +4.7 -6.4 ) x 10 8 M sun . The BBH decay time of (5.1 +60.5 -2.5 ) x 10 2 yr provides evidence for the occurrence of black hole mergers. This Letter will demonstrate the interesting possibility of black hole collisions to form a supermassive black hole in the process of evolution, one of the most spectacular natural phenomena in the universe.

Distinguishing spin-aligned and isotropic black hole populations with gravitational waves.

Science.gov (United States)

Farr, Will M; Stevenson, Simon; Miller, M Coleman; Mandel, Ilya; Farr, Ben; Vecchio, Alberto

2017-08-23

The direct detection of gravitational waves from merging binary black holes opens up a window into the environments in which binary black holes form. One signature of such environments is the angular distribution of the black hole spins. Binary systems that formed through dynamical interactions between already-compact objects are expected to have isotropic spin orientations (that is, the spins of the black holes are randomly oriented with respect to the orbit of the binary system), whereas those that formed from pairs of stars born together are more likely to have spins that are preferentially aligned with the orbit. The best-measured combination of spin parameters for each of the four likely binary black hole detections GW150914, LVT151012, GW151226 and GW170104 is the 'effective' spin. Here we report that, if the magnitudes of the black hole spins are allowed to extend to high values, the effective spins for these systems indicate a 0.015 odds ratio against an aligned angular distribution compared to an isotropic one. When considering the effect of ten additional detections, this odds ratio decreases to 2.9 × 10 -7 against alignment. The existing preference for either an isotropic spin distribution or low spin magnitudes for the observed systems will be confirmed (or overturned) confidently in the near future.

Effect of Copper on the Carrier Lifetime in Black Silicon

DEFF Research Database (Denmark)

Porte, Henrik; Turchinovich, Dmitry; Persheyev, Saydulla

2011-01-01

Black silicon is produced by laser annealing of a-Si:H films. During annealing, silicon microstructures are formed on the surface. We use time-resolved terahertz spectroscopy to study the photoconductivity dynamics in black silicon. We find that when a copper film is deposited on top of the a......-Si:H layer prior to laser annealing, the carrier lifetime of black silicon is significantly reduced....

Papulo-Nodular Reactions in Black Tattoos as Markers of Sarcoidosis: Study of 92 Tattoo Reactions from a Hospital Material.

Science.gov (United States)

Sepehri, Mitra; Hutton Carlsen, Katrina; Serup, Jørgen

2016-01-01

Sarcoidosis is, from historical data, suggested to be more prevalent among patients with tattoo reactions. We aimed to evaluate this association in a systematic study. This is a consecutive study of patients with tattoo complications, diagnosed in the "Tattoo Clinic" at Bispebjerg University Hospital in Copenhagen, Denmark, from 2008 to 2015, based on clinical assessment and histology. From the overall group of 494 tattoo complications in 406 patients, 92 reactions in 72 patients showed a papulo-nodular pattern studied for local and systemic sarcoidosis, since sarcoidosis is expected to be nodular. Of the 92 reactions with a papulo-nodular pattern, 27 (29%) reactions in 19 patients were diagnosed as cutaneous or systemic sarcoidosis, supported by histology; 65 (71%) were diagnosed as non-sarcoidosis due to histology and no clinical sarcoid manifestations. "Rush phenomenon" with concomitant reaction in many other black tattoos, triggered by a recent tattoo with a papulo-nodular reaction, was observed in 70% in the sarcoidosis group and 28% in the non-sarcoidosis group, indicating a predisposing factor which may be autoimmune and linked with sarcoidosis. Agglomerates of black pigment forming foreign bodies may in the predisposed individual trigger widespread reaction in the skin and internal organs. Black tattoos with papulo-nodular reactions should be seen as markers of sarcoidosis. Papulo-nodular reactions may, as triggers, induce widespread reactions in other black tattoos - a "rush phenomenon" - depending on individual predisposition. Sarcoidosis is estimated to be 500-fold increased in papulo-nodular reactions compared to the prevalence in the general population, and the association with black tattoos is strong. © 2017 S. Karger AG, Basel.

BOOK REVIEW: Introduction to Black Hole Physics Introduction to Black Hole Physics

Science.gov (United States)

Tanaka, Takahiro

2012-07-01

expected in the near future. Such hot topics are presented in Section 10: 'Black Holes and All That Jazz'. I would also consider the historical overview of the research on black holes given in Section 1 to be very interesting. Overall, I strongly recognised the intention of the authors not to go into too much detail; in this sense, I would say that the book has the aspect of a showcase of the frontiers of black hole physics. There are many topics which are very interesting but mathematically a little complicated; however, those subjects are appropriately treated so that the reader will not be overloaded with mathematical complexity. For example, in the discussion of black hole perturbation, only scalar field perturbation is discussed. The authors might have discussed gravitational wave perturbation, but this is much more complicated and the essential physics is mostly included in the simplest example of the scalar field. If I were one of the authors, I would consider adding more detailed explanations about several such advanced topics. However, the authors well know that such a challenge just presents a barrier to young students who are going to read this book, and really it is only an introduction to this interesting research field. This style might be the result of the long experience from the lectures over 30 years: the explanations of the subjects that the authors describe in detail are very carefully presented, avoiding logical gaps. In the preface, the authors state that they tried hard to answer students' questions as much as possible; I think that the authors' method in this respect is very successful.

Rotating circular strings, and infinite non-uniqueness of black rings

International Nuclear Information System (INIS)

Emparan, Roberto

2004-01-01

We present new self-gravitating solutions in five dimensions that describe circular strings, i.e., rings, electrically coupled to a two-form potential (as e.g., fundamental strings do), or to a dual magnetic one-form. The rings are prevented from collapsing by rotation, and they create a field analogous to a dipole, with no net charge measured at infinity. They can have a regular horizon, and we show that this implies the existence of an infinite number of black rings, labeled by a continuous parameter, with the same mass and angular momentum as neutral black rings and black holes. We also discuss the solution for a rotating loop of fundamental string. We show how more general rings arise from intersections of branes with a regular horizon (even at extremality), closely related to the configurations that yield the four-dimensional black hole with four charges. We reproduce the Bekenstein-Hawking entropy of a large extremal ring through a microscopic calculation. Finally, we discuss some qualitative ideas for a microscopic understanding of neutral and dipole black rings. (author)

ILLUMINATING BLACK HOLE BINARY FORMATION CHANNELS WITH SPINS IN ADVANCED LIGO

Energy Technology Data Exchange (ETDEWEB)

Rodriguez, Carl L. [MIT-Kavli Institute for Astrophysics and Space Research, 77 Massachusetts Avenue, 37-664H, Cambridge, MA 02139 (United States); Zevin, Michael; Pankow, Chris; Kalogera, Vasilliki; Rasio, Frederic A. [Center for Interdisciplinary Exploration and Research in Astrophysics (CIERA) and Department of Physics and Astronomy, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208 (United States)

2016-11-20

The recent detections of the binary black hole mergers GW150914 and GW151226 have inaugurated the field of gravitational-wave astronomy. For the two main formation channels that have been proposed for these sources, isolated binary evolution in galactic fields and dynamical formation in dense star clusters, the predicted masses and merger rates overlap significantly, complicating any astrophysical claims that rely on measured masses alone. Here, we examine the distribution of spin–orbit misalignments expected for binaries from the field and from dense star clusters. Under standard assumptions for black hole natal kicks, we find that black hole binaries similar to GW150914 could be formed with significant spin–orbit misalignment only through dynamical processes. In particular, these heavy-black hole binaries can only form with a significant spin–orbit anti -alignment in the dynamical channel. Our results suggest that future detections of merging black hole binaries with measurable spins will allow us to identify the main formation channel for these systems.

Aharonov–Bohm protection of black hole's baryon/skyrmion hair

Energy Technology Data Exchange (ETDEWEB)

Dvali, Gia [Arnold-Sommerfeld-Center for Theoretical Physics, Ludwig-Maximilians-Universität, 80333 München (Germany); Max-Planck-Institut für Physik, Werner-Heisenberg-Institut, 80805 München (Germany); Center for Cosmology and Particle Physics, Department of Physics, New York University, 4 Washington Place, New York, NY 10003 (United States); Gußmann, Alexander, E-mail: alexander.gussmann@physik.uni-muenchen.de [Arnold-Sommerfeld-Center for Theoretical Physics, Ludwig-Maximilians-Universität, 80333 München (Germany)

2017-05-10

The baryon/skyrmion correspondence implies that the baryon number is encoded into a topological surface integral. Under certain conditions that we clarify, this surface integral can be measured by an asymptotic observer in form of an Aharonov–Bohm phase-shift in an experiment in which the skyrmion passes through a loop of a probe string. In such a setup the baryon/skyrmion number must be respected by black holes, despite the fact that it produces no long-range classical field. If initially swallowed by a black hole, the baryon number must resurface in form of a classical skyrmion hair, after the black hole evaporates below a certain critical size. Needless to say, the respect of the baryon number by black holes is expected to have potentially-interesting astrophysical consequences.

Spawning of bluefin tuna in the black sea: historical evidence, environmental constraints and population plasticity

DEFF Research Database (Denmark)

Mackenzie, Brian R; Mariani, Patrizio

2012-01-01

The lucrative and highly migratory Atlantic bluefin tuna, Thunnus thynnus (Linnaeus 1758; Scombridae), used to be distributed widely throughout the north Atlantic Ocean, Mediterranean Sea and Black Sea. Its migrations have supported sustainable fisheries and impacted local cultures since antiquity...

Mutant of Japanese pear resistant to Black Spot Disease

International Nuclear Information System (INIS)

Sanada, T.; Nishida, T.; Ikeda, F.

1987-01-01

Full text: Nijisseike is one of the leading cultivars of Japanese pear (Pyrus serotinea Rehd.), but susceptible to black spot disease. Farmers try to prevent this disease by wrapping the fruit with a paper bag and by repeated spraying of fungicides. The disease is caused by a Japanese pear pathotype of Alternaria alternata (Fr.) Keissler. Susceptibility is controlled by a single dominant gene. In 1962, grafted trees of this cultivar were planted at a distance between 53 and 93 m from the 60 Co source in the gamma-field (daily dose 15-4 rad). One branch on a tree planted at 53 m was detected as resistant in 1981. Under field conditions, black spots were observed on many fruits and leaves of the original trees by natural infection in early July, however, they were not observed on the mutant. To examine the resistance of the mutant, artificial inoculations were made using spores of the pathogen and the host specific toxin produced by germinating spores. When some drops of the spore suspension are placed on leaves, the formation of black spots depends upon the leaf age. In a resistant cv. as Chojuro, black spot symptoms are formed only when inoculated on young leaves. An intermediate reaction was observed in the mutant, whereas the original Nijisseiki showed severe symptoms. When inoculation was made on matured fruit skins, no black spot was formed on the mutant just like on the resistant cv. Chojuro, while many small black spots were formed and grew into large spots overlapping each other on the susceptible cv. Nijisseiki. In case of the crude toxin inoculation (4-0.04 ppm) of cv. Nijisseiki black spots were formed on the surface of the susceptible fruit skin, and necrotic lesions at the cut end of detached small pieces of leaves, although reaction on fruit skins was weaker compared with inoculation by spores. However, no symptoms were observed from the toxin application on the mutant and the resistant cv. Chojuro. That the resistance of the mutant is classified as

State-space Manifold and Rotating Black Holes

CERN Document Server

Bellucci, Stefano

2010-01-01

We study a class of fluctuating higher dimensional black hole configurations obtained in string theory/ $M$-theory compactifications. We explore the intrinsic Riemannian geometric nature of Gaussian fluctuations arising from the Hessian of the coarse graining entropy, defined over an ensemble of brane microstates. It has been shown that the state-space geometry spanned by the set of invariant parameters is non-degenerate, regular and has a negative scalar curvature for the rotating Myers-Perry black holes, Kaluza-Klein black holes, supersymmetric $AdS_5$ black holes, $D_1$-$D_5$ configurations and the associated BMPV black holes. Interestingly, these solutions demonstrate that the principal components of the state-space metric tensor admit a positive definite form, while the off diagonal components do not. Furthermore, the ratio of diagonal components weakens relatively faster than the off diagonal components, and thus they swiftly come into an equilibrium statistical configuration. Novel aspects of the scali...

Quasinormal modes of Kerr-de Sitter black holes

International Nuclear Information System (INIS)

Yoshida, Shijun; Uchikata, Nami; Futamase, Toshifumi

2010-01-01

We calculate the fundamental quasinormal modes of the Kerr-de Sitter black hole for the first time. In order to calculate the quasinormal modes, we employ the master equations derived by Suzuki, Takasugi, and Umetsu, who transform the Teukolsky equations for the Kerr-de Sitter black hole into the standard form of the Heun's equation. The transformed functions are expanded around the outer horizon of the black hole or the symmetric axis in the Froebenius series whose coefficients satisfy a three-term recurrence relation. These three-term recurrence relations allow us to use Leaver's continued fraction method to calculate the angular separation constant and the quasinormal mode frequency. Any unstable fundamental quasinormal mode is not found in this paper. It is also observed that for some black holes characterized by a large mass parameter, some retrograde modes in the slow rotation limit become prograde as the black hole spin increases. This phenomenon does not occur for the fundamental modes of the Kerr black hole.

Pilot Survey On The Conservation Of Historical Buildings In Malaysia

OpenAIRE

Kamal, Kamarul_Syahril; AbWahab, Lilawati; Ahmad, A_Ghafar

2008-01-01

Historic buildings basically represents the single most visible aspect of our past history and culture. Like most other countries in the world, Malaysia has a rich legacy of historic buildings with outstanding craftsmanship and architecture quality. They form an impressive historic features and heritage of the past work of man. It is important to conserve and preserve historic buildings because they provide a sense of identity and continuity in a fast changing world for future generations. Ho...

Black Hole Solution of Einstein-Born-Infeld-Yang-Mills Theory

Directory of Open Access Journals (Sweden)

Kun Meng

2017-01-01

Full Text Available A new four-dimensional black hole solution of Einstein-Born-Infeld-Yang-Mills theory is constructed; several degenerated forms of the black hole solution are presented. The related thermodynamical quantities are calculated, with which the first law of thermodynamics is checked to be satisfied. Identifying the cosmological constant as pressure of the system, the phase transition behaviors of the black hole in the extended phase space are studied.

Black-hole-regulated star formation in massive galaxies

Science.gov (United States)

Martín-Navarro, Ignacio; Brodie, Jean P.; Romanowsky, Aaron J.; Ruiz-Lara, Tomás; van de Ven, Glenn

2018-01-01

Supermassive black holes, with masses more than a million times that of the Sun, seem to inhabit the centres of all massive galaxies. Cosmologically motivated theories of galaxy formation require feedback from these supermassive black holes to regulate star formation. In the absence of such feedback, state-of-the-art numerical simulations fail to reproduce the number density and properties of massive galaxies in the local Universe. There is, however, no observational evidence of this strongly coupled coevolution between supermassive black holes and star formation, impeding our understanding of baryonic processes within galaxies. Here we report that the star formation histories of nearby massive galaxies, as measured from their integrated optical spectra, depend on the mass of the central supermassive black hole. Our results indicate that the black-hole mass scales with the gas cooling rate in the early Universe. The subsequent quenching of star formation takes place earlier and more efficiently in galaxies that host higher-mass central black holes. The observed relation between black-hole mass and star formation efficiency applies to all generations of stars formed throughout the life of a galaxy, revealing a continuous interplay between black-hole activity and baryon cooling.

Black-hole-regulated star formation in massive galaxies.

Science.gov (United States)

Martín-Navarro, Ignacio; Brodie, Jean P; Romanowsky, Aaron J; Ruiz-Lara, Tomás; van de Ven, Glenn

2018-01-18

Supermassive black holes, with masses more than a million times that of the Sun, seem to inhabit the centres of all massive galaxies. Cosmologically motivated theories of galaxy formation require feedback from these supermassive black holes to regulate star formation. In the absence of such feedback, state-of-the-art numerical simulations fail to reproduce the number density and properties of massive galaxies in the local Universe. There is, however, no observational evidence of this strongly coupled coevolution between supermassive black holes and star formation, impeding our understanding of baryonic processes within galaxies. Here we report that the star formation histories of nearby massive galaxies, as measured from their integrated optical spectra, depend on the mass of the central supermassive black hole. Our results indicate that the black-hole mass scales with the gas cooling rate in the early Universe. The subsequent quenching of star formation takes place earlier and more efficiently in galaxies that host higher-mass central black holes. The observed relation between black-hole mass and star formation efficiency applies to all generations of stars formed throughout the life of a galaxy, revealing a continuous interplay between black-hole activity and baryon cooling.

Chandra Catches "Piranha" Black Holes

Science.gov (United States)

2007-07-01

had good evidence until now," said co-author Paul Martini, also of OSU. "This can help solve a couple of mysteries about galaxy clusters." One mystery is why there are so many blue, star-forming galaxies in young, distant clusters and fewer in nearby, older clusters. AGN are believed to expel or destroy cool gas in their host galaxy through powerful eruptions from the black hole. This may stifle star formation and the blue, massive stars will then gradually die off, leaving behind only the old, redder stars. This process takes about a billion years or more to take place, so a dearth of star-forming galaxies is only noticeable for older clusters. The process that sets the temperature of the hot gas in clusters when they form is also an open question. These new results suggest that even more AGN may have been present when most clusters were forming about ten billion years ago. Early heating of a cluster by large numbers of AGN can have a significant, long-lasting effect on the structure of a cluster by "puffing up" the gas. "In a few nearby clusters we've seen evidence for huge eruptions generated by supermassive black holes. But this is sedate compared to what might be going on in younger clusters," said Eastman. These results appeared in the July 20th issue of The Astrophysical Journal Letters. NASA's Marshall Space Flight Center, Huntsville, Ala., manages the Chandra program for the agency's Science Mission Directorate. The Smithsonian Astrophysical Observatory controls science and flight operations from the Chandra X-ray Center in Cambridge, Mass. Additional information and images are available at: Additional information and images are available at: http://chandra.harvard.edu and http://chandra.nasa.gov

"Thank You, Black Twitter": State Violence, Digital Counterpublics, and Pedagogies of Resistance

Science.gov (United States)

Hill, Marc Lamont

2018-01-01

In this article, I examine the role of Black Twitter as a "digital counterpublic" that enables critical pedagogy, political organizing, and both symbolic and material forms of resistance to anti-Black state violence within the United States. Focusing primarily on post-Ferguson events, I spotlight the ways that Black people have used…

"Community Psychology Is for Poor, Black People": Pedagogy and Teaching of Community Psychology in South Africa

Science.gov (United States)

Carolissen, Ronelle; Rohleder, Poul; Bozalek, Vivienne; Swartz, Leslie; Leibowitz, Brenda

2010-01-01

The term "community" holds historical connotations of political, economic, and social disadvantage in South Africa. Many South African students tend to interpret the term "community" in ways that suggest that community and community psychology describe the experiences of exclusively poor, black people. Critical pedagogies that…

Heaviest Stellar Black Hole Discovered in Nearby Galaxy

Science.gov (United States)

2007-10-01

Astronomers have located an exceptionally massive black hole in orbit around a huge companion star. This result has intriguing implications for the evolution and ultimate fate of massive stars. The black hole is part of a binary system in M33, a nearby galaxy about 3 million light years from Earth. By combining data from NASA's Chandra X-ray Observatory and the Gemini telescope on Mauna Kea, Hawaii, the mass of the black hole, known as M33 X-7, was determined to be 15.7 times that of the Sun. This makes M33 X-7 the most massive stellar black hole known. A stellar black hole is formed from the collapse of the core of a massive star at the end of its life. Chandra X-ray Image of M33 X-7 Chandra X-ray Image of M33 X-7 "This discovery raises all sorts of questions about how such a big black hole could have been formed," said Jerome Orosz of San Diego State University, lead author of the paper appearing in the October 18th issue of the journal Nature. M33 X-7 orbits a companion star that eclipses the black hole every three and a half days. The companion star also has an unusually large mass, 70 times that of the Sun. This makes it the most massive companion star in a binary system containing a black hole. Hubble Optical Image of M33 X-7 Hubble Optical Image of M33 X-7 "This is a huge star that is partnered with a huge black hole," said coauthor Jeffrey McClintock of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass. "Eventually, the companion will also go supernova and then we'll have a pair of black holes." The properties of the M33 X-7 binary system - a massive black hole in a close orbit around a massive companion star - are difficult to explain using conventional models for the evolution of massive stars. The parent star for the black hole must have had a mass greater than the existing companion in order to have formed a black hole before the companion star. Gemini Optical Image of M33 X-7 Gemini Optical Image of M33 X-7 Such a massive star would

NASA's Chandra Finds Black Holes Are "Green"

Science.gov (United States)

2006-04-01

Black holes are the most fuel efficient engines in the Universe, according to a new study using NASA's Chandra X-ray Observatory. By making the first direct estimate of how efficient or "green" black holes are, this work gives insight into how black holes generate energy and affect their environment. The new Chandra finding shows that most of the energy released by matter falling toward a supermassive black hole is in the form of high-energy jets traveling at near the speed of light away from the black hole. This is an important step in understanding how such jets can be launched from magnetized disks of gas near the event horizon of a black hole. Illustration of Fuel for a Black Hole Engine Illustration of Fuel for a Black Hole Engine "Just as with cars, it's critical to know the fuel efficiency of black holes," said lead author Steve Allen of the Kavli Institute for Particle Astrophysics and Cosmology at Stanford University, and the Stanford Linear Accelerator Center. "Without this information, we cannot figure out what is going on under the hood, so to speak, or what the engine can do." Allen and his team used Chandra to study nine supermassive black holes at the centers of elliptical galaxies. These black holes are relatively old and generate much less radiation than quasars, rapidly growing supermassive black holes seen in the early Universe. The surprise came when the Chandra results showed that these "quiet" black holes are all producing much more energy in jets of high-energy particles than in visible light or X-rays. These jets create huge bubbles, or cavities, in the hot gas in the galaxies. Animation of Black Hole in Elliptical Galaxy Animation of Black Hole in Elliptical Galaxy The efficiency of the black hole energy-production was calculated in two steps: first Chandra images of the inner regions of the galaxies were used to estimate how much fuel is available for the black hole; then Chandra images were used to estimate the power required to produce

Old ages of two historical Romanian trees assessed by AMS radiocarbon dating

International Nuclear Information System (INIS)

Patrut, Adrian; Reden, Karl F. von; Lowy, Daniel A.; Patrut, Roxana T.; Lucian Vaida, D.; Margineanu, Dragos

2013-01-01

Two large Romanian poplars are considered to be associated with significant historical events of the past. In order to verify these claims, wood samples collected from the broken trunks of the two poplars were radiocarbon dated by AMS. The oldest radiocarbon dates were found to be 275 ± 20 bp for the black poplar of Mocod and 316 ± 22 bp for the gray poplar of Rafaila. These values correspond to calibrated ages of 365 ± 10 and 465 ± 25 years, respectively. The dating results indicate old ages for the two trees, i.e., 455 years for the Mocod poplar and 560 years for the Rafaila poplar. Such age values validate historical information on the two large Romanian trees.

Historical Medical Value of Donguibogam

Directory of Open Access Journals (Sweden)

Bong-Keun Song

2016-03-01

Full Text Available Oriental medicine, since its origin in China, has had a long history extending over 2000 years. Today, it comprises several types of medicine predominately practiced in East Asia, including traditional Chinese, traditional Korean, and Kampo medicine. The distinctive medical system of traditional Korean medicine was established shortly after the publication of Donguibogam by Dr. Heo Jun in 1613. Donguibogam is highly acclaimed across East Asia; in 2009, in light of its historical medical value, the United Nations Educational, Scientific, and Cultural Organization registered the book on its cultural heritage list. Here, we review the historical medical value of Donguibogam. The findings confirm that Donguibogam developed a unique and independent form of traditional Korean medicine and innovatively reformed the disease classification system. Moreover, Donguibogam emphasized the importance of disease prevention and medical pragmatism. This book also accelerated the development of folk medicine. Owing to its historical medical value, Donguibogam is now considered the 'bible' of Oriental medicine. Its wide acceptance has contributed to the expansion of Korean medicine utilization among the general public. Donguibogam has also played an important role in the establishment of traditional Korean medicine as a universally valid and original form of medicine, independent of traditional Chinese medicine.

Black holes and beyond

Energy Technology Data Exchange (ETDEWEB)

NONE

2002-02-01

Belief in the existence of black holes is the ultimate act of faith for a physicist. First suggested by the English clergyman John Michell in the year 1784, the gravitational pull of a black hole is so strong that nothing - not even light - can escape. Gravity might be the weakest of the fundamental forces but black-hole physics is not for the faint-hearted. Black holes present obvious problems for would-be observers because they cannot, by definition, be seen with conventional telescopes - although before the end of the decade gravitational-wave detectors should be able to study collisions between black holes. Until then astronomers can only infer the existence of a black hole from its gravitational influence on other matter, or from the X-rays emitted by gas and dust as they are dragged into the black hole. However, once this material passes through the 'event horizon' that surrounds the black hole, we will never see it again - not even with X-ray specs. Despite these observational problems, most physicists and astronomers believe that black holes do exist. Small black holes a few kilometres across are thought to form when stars weighing more than about two solar masses collapse under the weight of their own gravity, while supermassive black holes weighing millions of solar masses appear to be present at the centre of most galaxies. Moreover, some brave physicists have proposed ways to make black holes - or at least event horizons - in the laboratory. The basic idea behind these 'artificial black holes' is not to compress a large amount of mass into a small volume, but to reduce the speed of light in a moving medium to less than the speed of the medium and so create an event horizon. The parallels with real black holes are not exact but the experiments could shed new light on a variety of phenomena. The first challenge, however, is to get money for the research. One year on from a high-profile meeting on artificial black holes in London, for

Black hole state evolution, final state and Hawking radiation

International Nuclear Information System (INIS)

Ahn, D

2012-01-01

The effect of a black hole state evolution on the Hawking radiation is studied using the final state boundary condition. It is found that the thermodynamic or statistical mechanical properties of a black hole depend strongly on the unitary evolution operator S, which determines the black hole state evolution. When the operator S is random unitary or pseudo-random unitary, a black hole emits thermal radiation as predicted by Hawking three decades ago. In particular, when the black hole mass of the final state vanishes, Hawking’s original result is retrieved. On the other hand, it is found that the emission of the Hawking radiation could be suppressed when the evolution of a black hole state is determined by the generator of the coherent state. Such a case can occur for some primordial black holes with Planck scale mass formed by primordial density fluctuations through the process of squeezing the zero-point quantum fluctuation of a scalar field. Those primordial black holes can survive until the present time and can contribute to cold dark matter. (paper)

Drifting black aurorae?

International Nuclear Information System (INIS)

Schoute-Vanneck, H.; Scourfield, M.W.J.; Nielsen, E.

1990-01-01

Characteristics of eastward drifting forms, previously described in the literature as black aurorae, have been identified in low-light level TV camera data. The TV field of view was within the field of view of STARE and that of an all-sky camera. On the basis of these observations the authors propose that these auroral forms are a manifestation of folds or waves on the borders of auroral bands propagating along the dark regions between neighboring auroral bands. Conditions under which the folds or waves occur are compatible with their formation by the Kelvin-Helmholtz electrostatic instability

Black holes in massive close binaries - observational data and evolutionary status

International Nuclear Information System (INIS)

Tutukov, A.V.; Cherepashchuk, A.M.; Moskovskii Gosudarstvennyi Universitet, Moscow, USSR)

1985-01-01

The available information on the mass of four candidate black holes in X-ray binary systems is summarized; these systems are compared with neutron star binaries with regard to the mass of their components. In mass, the relativistic objects form two distinct groups, neutron stars with masses equal to about 1-2 solar masses and black hole candidates with masses equal to about 10-60 solar masses (there seem to be no intermediate cases), but there is no correlation with the mass of the optical star. Mass exchange between the optical component of a close binary and its neutron star companion would be unlikely to produce a black hole more massive than 5-7 solar masses. Instead, the black holes having masses greater than about 10 solar masses might result from core collapse in stars of initial mass equating 20-100 solar masses through either a rise in the presupernova core mass or weakness of the magnetic field. The (10-30)-fold disparity in the incidence of black holes coupled with OB stars and with radio pulsars could indicate that black holes tend to form in pairs. 36 references

Black-on-white polymer-stabilized cholesteric formulations

Science.gov (United States)

West, John L.; Magyar, Gregory R.; Francl, James J.; Nixon, Christine M.

1995-08-01

Recent research by Doane, Yang, and Chien demonstrated the use of cholesteric liquid crystals in multiplexed, high resolution, reflective diplays. These materials utilize the bistability of the cholesteric planar and focal conic states for displays with a colored image on a black background. Many commercial applications of these materials, such as electronic books and newspapers, portable faxes and personal data assistants, require, or at least prefer, black-on- white images. We report on relatively high polymer content (equalsV 20% by weight) dispersions of cholesteric liquid crystals that produce a white, reflecting, planar state. The polymer network appears to form cholesteric domains with varying pitch lengths resulting in planar states that reflect in the red, green, and blue portions of the spectrum. Utilizing a black absorbing layer behind a display using these materials offers white images on a black background, or vice-versa.

Enthalpy and the mechanics of AdS black holes

International Nuclear Information System (INIS)

Kastor, David; Traschen, Jennie; Ray, Sourya

2009-01-01

We present geometric derivations of the Smarr formula for static AdS black holes and an expanded first law that includes variations in the cosmological constant. These two results are further related by a scaling argument based on Euler's theorem. The key new ingredient in the constructions is a two-form potential for the static Killing field. Surface integrals of the Killing potential determine the coefficient of the variation of Λ in the first law. This coefficient is proportional to a finite, effective volume for the region outside the AdS black hole horizon, which can also be interpreted as minus the volume excluded from a spatial slice by the black hole horizon. This effective volume also contributes to the Smarr formula. Since Λ is naturally thought of as a pressure, the new term in the first law has the form of effective volume times change in pressure that arises in the variation of the enthalpy in classical thermodynamics. This and related arguments suggest that the mass of an AdS black hole should be interpreted as the enthalpy of the spacetime.

To Test or Not to Test: Barriers and Solutions to Testing African American College Students for HIV at a Historically Black College/University.

Science.gov (United States)

Hall, Naomi M; Peterson, Jennifer; Johnson, Malynnda

2014-01-01

Young African Americans are disproportionately affected by sexually transmitted infections, including HIV. The purpose was to identify reasons that African American college students at a historically Black college/university (HBCU) identified as barriers to HIV testing, and how these barriers can be removed. Fifty-seven heterosexual-identified undergraduate students (ages 18-25) attending an HBCU in the southeastern US participated in a mixed method study. Latent content analytic techniques were used to code the transcripts for themes and categories, and representative quotations were used in the findings. Quantitative data indicates high levels of perceived knowledge about HIV transmission, low perception of risk and concern of contracting HIV, yet continued sexual risk behavior. Qualitative data indicates three main themes used to avoid testing and three themes to encourage testing. Students were forthcoming in discussing the themes around avoidance of HIV testing (being scared to know, preferring not to know, and lack of discussion about HIV) and encouraging testing (group testing, increasing basic knowledge, and showing the reality of HIV). It is important for college healthcare professionals, researchers, and officials to identify appropriate ways to encourage HIV testing, and promote testing as part of overall health.

The historical character of human nature in Freud's theories.

Science.gov (United States)

Zilbersheid, Uri

2013-06-01

In Freud' theories of human development, human nature is described and analyzed as essentially historical. At the core of human history is the restructuring of the sexual instinct and the death instinct (or its unique form as destructive impulses). The conscious, asked-for shaping of these two instincts, under the rule of the "reality principle", forms the basis of human society at all stages. This conscious restructuring has also unintended, unasked-for results, which are part of the historically developing human nature. The historical choice has been the building of human society as a social complex based on the de-eroticization of both the individual and society. Freud suggested that the historical process of changing human nature and maintaining the achieved new structure has mainly been an enterprise of enlightened political elite, which has imposed (in all societies) the various elements of the new nature upon the ordinary people. Human history is essentially a deed of the political sphere. In viewing human nature as consisting of both asked-for and unasked-for results of human conscious purposeful activity Freud belongs to the same historical school as Marx.

Quantitative approaches to information recovery from black holes

Energy Technology Data Exchange (ETDEWEB)

Balasubramanian, Vijay [David Rittenhouse Laboratory, University of Pennsylvania, 209 South 33rd Street, Philadelphia, PA 19104 (United States); Czech, Bartlomiej, E-mail: vijay@physics.upenn.edu, E-mail: czech@phas.ubc.ca [Department of Physics and Astronomy, University of British Columbia, 6224 Agricultural Road, Vancouver, BC V6T 1Z1 (Canada)

2011-08-21

The evaporation of black holes into apparently thermal radiation poses a serious conundrum for theoretical physics: at face value, it appears that in the presence of a black hole, quantum evolution is non-unitary and destroys information. This information loss paradox has its seed in the presence of a horizon causally separating the interior and asymptotic regions in a black hole spacetime. A quantitative resolution of the paradox could take several forms: (a) a precise argument that the underlying quantum theory is unitary, and that information loss must be an artifact of approximations in the derivation of black hole evaporation, (b) an explicit construction showing how information can be recovered by the asymptotic observer, (c) a demonstration that the causal disconnection of the black hole interior from infinity is an artifact of the semiclassical approximation. This review summarizes progress on all these fronts. (topical review)

Radiation transport around Kerr black holes

Science.gov (United States)

Schnittman, Jeremy David

This Thesis describes the basic framework of a relativistic ray-tracing code for analyzing accretion processes around Kerr black holes. We begin in Chapter 1 with a brief historical summary of the major advances in black hole astrophysics over the past few decades. In Chapter 2 we present a detailed description of the ray-tracing code, which can be used to calculate the transfer function between the plane of the accretion disk and the detector plane, an important tool for modeling relativistically broadened emission lines. Observations from the Rossi X-Ray Timing Explorer have shown the existence of high frequency quasi-periodic oscillations (HFQPOs) in a number of black hole binary systems. In Chapter 3, we employ a simple "hot spot" model to explain the position and amplitude of these HFQPO peaks. The power spectrum of the periodic X-ray light curve consists of multiple peaks located at integral combinations of the black hole coordinate frequencies, with the relative amplitude of each peak determined by the orbital inclination, eccentricity, and hot spot arc length. In Chapter 4, we introduce additional features to the model to explain the broadening of the QPO peaks as well as the damping of higher frequency harmonics in the power spectrum. The complete model is used to fit the power spectra observed in XTE J1550-564, giving confidence limits on each of the model parameters. In Chapter 5 we present a description of the structure of a relativistic alpha- disk around a Kerr black hole. Given the surface temperature of the disk, the observed spectrum is calculated using the transfer function mentioned above. The features of this modified thermal spectrum may be used to infer the physical properties of the accretion disk and the central black hole. In Chapter 6 we develop a Monte Carlo code to calculate the detailed propagation of photons from a hot spot emitter scattering through a corona surrounding the black hole. The coronal scattering has two major observable

National Register of Historic Places multiple property documentation form -- Historic, archaeological, and traditional cultural properties of the Hanford Site, Washington

Energy Technology Data Exchange (ETDEWEB)

Nickens, P.R.

1997-08-01

The US Department of Energy`s Hanford Site encompasses an area of 560 square miles on the Columbia River in southeastern Washington. Since 1943, the Hanford Site has existed as a protected area for activities primarily related to the production of radioactive materials for national defense uses. For cultural resources on the Hanford Site, establishment of the nuclear reservation as a high security area, with public access restricted, has resulted in a well-protected status, although no deliberate resource protection measures were in effect to mitigate effects of facilities construction and associated activities. Thus, the Hanford Site contains an extensive record of aboriginal archaeological sites and Native American cultural properties, along with pre-Hanford Euro-American sites (primarily archaeological in nature with the removal of most pre-1943 structures), and a considerable number of Manhattan Project/Cold War era buildings and structures. The recent mission change from production to clean up and disposal of DOE lands created a critical need for development and implementation of new and different cultural resource management strategies. DOE-RL has undertaken a preservation planning effort for the Hanford Site. The intent of this Plan is to enable DOE-RL to organize data and develop goals, objectives, and priorities for the identification, evaluation, registration, protection, preservation, and enhancement of the Site`s historical and cultural properties. Decisions made about the identification, evaluation, registration and treatment of historic properties are most aptly made when relationships between individual properties and other similar properties are considered. The historic context and the multiple property documentation (NTD) process provides DOE-RL the organizational framework for these decisions. Once significant patterns are identified, contexts developed, and expected properties are defined, the NTD process provides the foundation for future

Massive Black Holes and Galaxies

CERN Multimedia

CERN. Geneva

2016-01-01

Evidence has been accumulating for several decades that many galaxies harbor central mass concentrations that may be in the form of black holes with masses between a few million to a few billion time the mass of the Sun. I will discuss measurements over the last two decades, employing adaptive optics imaging and spectroscopy on large ground-based telescopes that prove the existence of such a massive black hole in the Center of our Milky Way, beyond any reasonable doubt. These data also provide key insights into its properties and environment. Most recently, a tidally disrupting cloud of gas has been discovered on an almost radial orbit that reached its peri-distance of ~2000 Schwarzschild radii in 2014, promising to be a valuable tool for exploring the innermost accretion zone. Future interferometric studies of the Galactic Center Black hole promise to be able to test gravity in its strong field limit.

ECOLOGICAL SAFETY OF CITIZENS OF RECREATIONAL ZONES OF THE BLACK SEA

Directory of Open Access Journals (Sweden)

Г. Білявський

2012-04-01

Full Text Available The article is devoted to meaningfulness estimation of ecological control of sea aquatory in forming ofsafety ecological conditions for citizens of the Black Sea. The pecularity and the role of technogenic pollution ofsea aquatory of the Black Sea are estimated. The degrees of ecological safety and negative influences of technogenicobjects on people living in the Black Sea coast are defined. The reccomendations for ecologization of recreationalzones of the Black Seat are characterized. The main goal of the work is the ecological estimation of livingconditions for sitizens in the Black Sea on the bases of using of methodology of complex searching andmarking of protecting laws

Identification and synthetic modeling of factors affecting American black duck populations

Science.gov (United States)

Conroy, Michael J.; Miller, Mark W.; Hines, James E.

2002-01-01

We reviewed the literature on factors potentially affecting the population status of American black ducks (Anas rupribes). Our review suggests that there is some support for the influence of 4 major, continental-scope factors in limiting or regulating black duck populations: 1) loss in the quantity or quality of breeding habitats; 2) loss in the quantity or quality of wintering habitats; 3) harvest, and 4) interactions (competition, hybridization) with mallards (Anas platyrhychos) during the breeding and/or wintering periods. These factors were used as the basis of an annual life cycle model in which reproduction rates and survival rates were modeled as functions of the above factors, with parameters of the model describing the strength of these relationships. Variation in the model parameter values allows for consideration of scientific uncertainty as to the degree each of these factors may be contributing to declines in black duck populations, and thus allows for the investigation of the possible effects of management (e.g., habitat improvement, harvest reductions) under different assumptions. We then used available, historical data on black duck populations (abundance, annual reproduction rates, and survival rates) and possible driving factors (trends in breeding and wintering habitats, harvest rates, and abundance of mallards) to estimate model parameters. Our estimated reproduction submodel included parameters describing negative density feedback of black ducks, positive influence of breeding habitat, and negative influence of mallard densities; our survival submodel included terms for positive influence of winter habitat on reproduction rates, and negative influences of black duck density (i.e., compensation to harvest mortality). Individual models within each group (reproduction, survival) involved various combinations of these factors, and each was given an information theoretic weight for use in subsequent prediction. The reproduction model with highest

Information field for historical research

Directory of Open Access Journals (Sweden)

Sviatets, Yu. A.

2017-09-01

Full Text Available The article analyzes the main information collision of historical knowledge, which consists in physical inaccessibility of events and phenomena of the past as an object of historical science for a historian as an investigator. The aim of the research is to formulate and discuss a working hypothesis about the information field of historical science. The article provides an analytical background on the main ideas and approaches in the field of modern information field theory. The author carries out the projection of the main provisions of the information field theory on historical research. It is shown that the information field is a really existing information carrier that provides its acquisition, transportation, storage and visualization, as well as provides information and knowledge recorded in various forms, realizes cultural communications. One of the manifestations of such a culture is the sign systems, which determine certain contexts. Signs are characterized by polysemy. Despite artificial origin, semiotic reality is objective. Simultaneously, signs provide intellectual activity of people. Mental signs in the historical process of use by society acquire additional meanings, generating new symbols. Polysemy shapes the problem of epistemological uncertainty of two stages – identifying the problem and solving it. Historians as researchers resort to cognitive models, which, thanks to the translational function, ensure the transfer of information from the known to the unknown. One of the explanations of polysemy is the theory of conceptual integration, according to which the structures of the original mental spaces are projected onto a new, constructed, mental space – blend. This is the result of a personʼs intellectual ability to create new meanings on the basis of the available ones. Since signs and symbols are multi-valued, they form a multiplicity of retrospective scenarios of historical research at the stage of problem formulation

Black Silicon Solar Cells with Black Ribbons

DEFF Research Database (Denmark)

Davidsen, Rasmus Schmidt; Tang, Peter Torben; Mizushima, Io

2016-01-01

We present the combination of mask-less reactive ion etch (RIE) texturing and blackened interconnecting ribbons as a method for obtaining all-black solar panels, while using conventional, front-contacted solar cells. Black silicon made by mask-less reactive ion etching has total, average...... in the range 15.7-16.3%. The KOH-textured reference cell had an efficiency of 17.9%. The combination of black Si and black interconnecting ribbons may result in aesthetic, all-black panels based on conventional, front-contacted silicon solar cells....... reflectance below 0.5% across a 156x156 mm2 silicon (Si) wafer. Black interconnecting ribbons were realized by oxidizing copper resulting in reflectance below 3% in the visible wavelength range. Screen-printed Si solar cells were realized on 156x156 mm2 black Si substrates with resulting efficiencies...

Inventory of coastal protected areas and historical heritage sites (North Bulgarian coast)

Science.gov (United States)

Palazov, Atanas; Stancheva, Margarita; Stanchev, Hristo; Krastev, Anton; Peev, Preslav

2015-04-01

Coastal protected areas and historical heritage sites in Bulgaria are established by national policy instruments/laws and EU Directives to protect a wide range of natural and cultural resources along the coast. Within the framework of HERAS Project (Submarine Archaeological Heritage of the Western Black Sea Shelf), financed by European Union under the CBC Program Romania-Bulgaria, we made an inventory and identification of protected areas, nature reserves, monuments, parks and onshore historical sites along the North Bulgarian coast (NUTS III level). The adjacent coastline is 96 km long between cape Sivriburun to the border of Romania on the north and cape Ekrene on the south. Coastal zone here is mostly undeveloped and low urbanized compared to other coastal regions in Bulgaria. It comprises of large sand beaches, vast sand dunes, up to 70 m spectacular high limestone cliffs, coastal fresh-water lakes, wetlands etc. This coastal section includes also one of the most important wetlands and it is migration corridor for many protected birds in Bulgaria, that host one of the rarest ecosystem types with national and international conservational value. Added to ecosystem values, the region is also an archeologically important area, where numerous underwater and coastal archaeological sites from different periods have been discovered - Prehistory, Antiquity (ancient Greek, Hellenistic, Roman), Mediaeval (Early Byzantium, Bulgarian). Research was made within 2100 m zone from the coastline (in accordance with zones defined by the Black Sea Coastal Development Act) for territories with protected status in the framework of many national laws and EU Directives. The total area of this strip zone is 182, 6 km2 and around 67% is under protection. There are 11 unique NATURA 2000 protected areas (6 Special Protection Areas (SPAs) and 5 Sites of Communities Importance (SCI), 2 nature reserves and 1 Nature Park. Some of them are also onshore historical sites. In Bulgaria such sites

This Bridge Called My Leadership: An Essay on Black Women as Bridge Leaders in Education

Science.gov (United States)

Horsford, Sonya Douglass

2012-01-01

The purpose of this essay is to contextualize the existing research literature on leadership for diversity, equity, and social justice in education with "bridge leadership" as historically practiced by Black women leaders in the USA. Its primary aim is to demonstrate how the intersection of race and gender as experienced by the Black…

Dark matter influence on black objects thermodynamics

Science.gov (United States)

Rogatko, Marek; Wojnar, Aneta

2018-05-01

Physical process version of the first law of black hole thermodynamics in Einstein-Maxwell dark matter gravity was derived. The dark matter sector is mimicked by the additional U(1)-gauge field coupled to the ordinary Maxwell one. By considering any cross section of the black hole event horizon to the future of the bifurcation surface, the equilibrium state version of the first law of black hole mechanics was achieved. The considerations were generalized to the case of Einstein-Yang-Mills dark matter gravity theory. The main conclusion is that the influence of dark matter is crucial in the formation process of black objects. This fact may constitute the explanation of the recent observations of the enormous mass of the super luminous quasars formed in a relatively short time after Big Bang. We also pay attention to the compact binaries thermodynamics, when dark matter sector enters the game.

Rethinking historical trauma.

Science.gov (United States)

Kirmayer, Laurence J; Gone, Joseph P; Moses, Joshua

2014-06-01

Recent years have seen the rise of historical trauma as a construct to describe the impact of colonization, cultural suppression, and historical oppression of Indigenous peoples in North America (e.g., Native Americans in the United States, Aboriginal peoples in Canada). The discourses of psychiatry and psychology contribute to the conflation of disparate forms of violence by emphasizing presumptively universal aspects of trauma response. Many proponents of this construct have made explicit analogies to the Holocaust as a way to understand the transgenerational effects of genocide. However, the social, cultural, and psychological contexts of the Holocaust and of post-colonial Indigenous "survivance" differ in many striking ways. Indeed, the comparison suggests that the persistent suffering of Indigenous peoples in the Americas reflects not so much past trauma as ongoing structural violence. The comparative study of genocide and other forms of massive, organized violence can do much to illuminate both common mechanisms and distinctive features, and trace the looping effects from political processes to individual experience and back again. The ethics and pragmatics of individual and collective healing, restitution, resilience, and recovery can be understood in terms of the self-vindicating loops between politics, structural violence, public discourse, and embodied experience. © The Author(s) 2014 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

Historical Submerged Aquatic Vegetation (SAV) Distributions from Coastal Alabama, Gulf of Mexico from 1940-01-01 to 1966-10-21 (NCEI Accession 0162477)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Historic black and white aerial photographs of coastal Alabama (Mobile Bay and adjacent waters) from 1940, 1955, and 1966 were digitized and georeferenced using Blue...

D Visualization of a Timber Frame Historic Building: Partite Usage and its Impact on the Structural System

Science.gov (United States)

Günay, S.

2017-08-01

Throughout their lifetime, historic buildings might be altered for different kind of usage for different purposes. If this new function or new usage requires utilization of the building in separate units, this separation might affect the historic building's functionality and structure and as a result its overall condition. Yorguc Pasa Mansion conservation project was prepared as a part of the Middle East Technical University (METU) Master's Program in Documentation and Conservation of Historic Monuments and Sites for the historic Yorguc Pasa Mansion. The mansion is a 19th century Ottoman Period timber frame building in Amasya, a Black Sea Region city in Turkey that has traces from different civilizations such as Hittites, Greeks, Romans and Ottomans. This paper aims to discuss the affects of the partite usage on structural conditions of timber frame buildings with the case study of Amasya Yorguc Pasa Mansion through the 3D visualized structural systems.

Black-White Disparities in Breast Cancer Subtype: The Intersection of Socially Patterned Stress and Genetic Expression

Directory of Open Access Journals (Sweden)

Erin Linnenbringer

2017-11-01

Full Text Available Hormone receptor negative (HR- breast cancer subtypes are etiologically distinct from the more common, less aggressive, and more treatable form of estrogen receptor positive (ER+ breast cancer. Numerous population-based studies have found that, in the United States, Black women are 2 to 3 times more likely to develop HR- breast cancer than White women. Much of the existing research on racial disparities in breast cancer subtype has focused on identifying predisposing genetic factors associated with African ancestry. This approach fails to acknowledge that racial stratification shapes a wide range of environmental and social exposures over the life course. Human stress genomics considers the role of individual stress perceptions on gene expression. Yet, the role of structurally rooted biopsychosocial processes that may be activated by the social patterning of stressors in an historically unequal society, whether perceived by individual black women or not, could also impact cellular physiology and gene expression patterns relevant to HR- breast cancer etiology. Using the weathering hypothesis as our conceptual framework, we develop a structural perspective for examining racial disparities in breast cancer subtypes, integrating important findings from the stress biology, breast cancer epidemiology, and health disparities literatures. After integrating key findings from these largely independent literatures, we develop a theoretically and empirically guided framework for assessing potential multilevel factors relevant to the development of HR- breast cancer disproportionately among Black women in the US. We hypothesize that a dynamic interplay among socially patterned psychosocial stressors, physiological & behavioral responses, and genomic pathways contribute to the increased risk of HR- breast cancer among Black women. This work provides a basis for exploring potential alternative pathways linking the lived experience of race to the risk of HR

Black-White Disparities in Breast Cancer Subtype: The Intersection of Socially Patterned Stress and Genetic Expression.

Science.gov (United States)

Linnenbringer, Erin; Gehlert, Sarah; Geronimus, Arline T

2017-01-01

Hormone receptor negative (HR-) breast cancer subtypes are etiologically distinct from the more common, less aggressive, and more treatable form of estrogen receptor positive (ER+) breast cancer. Numerous population-based studies have found that, in the United States, Black women are 2 to 3 times more likely to develop HR- breast cancer than White women. Much of the existing research on racial disparities in breast cancer subtype has focused on identifying predisposing genetic factors associated with African ancestry. This approach fails to acknowledge that racial stratification shapes a wide range of environmental and social exposures over the life course. Human stress genomics considers the role of individual stress perceptions on gene expression. Yet, the role of structurally rooted biopsychosocial processes that may be activated by the social patterning of stressors in an historically unequal society, whether perceived by individual black women or not, could also impact cellular physiology and gene expression patterns relevant to HR- breast cancer etiology. Using the weathering hypothesis as our conceptual framework, we develop a structural perspective for examining racial disparities in breast cancer subtypes, integrating important findings from the stress biology, breast cancer epidemiology, and health disparities literatures. After integrating key findings from these largely independent literatures, we develop a theoretically and empirically guided framework for assessing potential multilevel factors relevant to the development of HR- breast cancer disproportionately among Black women in the US. We hypothesize that a dynamic interplay among socially patterned psychosocial stressors, physiological & behavioral responses, and genomic pathways contribute to the increased risk of HR- breast cancer among Black women. This work provides a basis for exploring potential alternative pathways linking the lived experience of race to the risk of HR- breast cancer, and

Primordial Regular Black Holes: Thermodynamics and Dark Matter

Directory of Open Access Journals (Sweden)

José Antonio de Freitas Pacheco

2018-05-01

Full Text Available The possibility that dark matter particles could be constituted by extreme regular primordial black holes is discussed. Extreme black holes have zero surface temperature, and are not subjected to the Hawking evaporation process. Assuming that the common horizon radius of these black holes is fixed by the minimum distance that is derived from the Riemann invariant computed from loop quantum gravity, the masses of these non-singular stable black holes are of the order of the Planck mass. However, if they are formed just after inflation, during reheating, their initial masses are about six orders of magnitude higher. After a short period of growth by the accretion of relativistic matter, they evaporate until reaching the extreme solution. Only a fraction of 3.8 × 10−22 of relativistic matter is required to be converted into primordial black holes (PBHs in order to explain the present abundance of dark matter particles.

Status of underrepresented minority and female faculty at medical schools located within Historically Black Colleges and in Puerto Rico

Directory of Open Access Journals (Sweden)

Emily M. Mader

2016-03-01

Full Text Available Background and objectives: To assess the impact of medical school location in Historically Black Colleges and Universities (HBCU and Puerto Rico (PR on the proportion of underrepresented minorities in medicine (URMM and women hired in faculty and leadership positions at academic medical institutions. Method: AAMC 2013 faculty roster data for allopathic medical schools were used to compare the racial/ethnic and gender composition of faculty and chair positions at medical schools located within HBCU and PR to that of other medical schools in the United States. Data were compared using independent sample t-tests. Results: Women were more highly represented in HBCU faculty (mean HBCU 43.5% vs. non-HBCU 36.5%, p=0.024 and chair (mean HBCU 30.1% vs. non-HBCU 15.6%, p=0.005 positions and in PR chair positions (mean PR 38.23% vs. non-PR 15.38%, p=0.016 compared with other allopathic institutions. HBCU were associated with increased African American representation in faculty (mean HBCU 59.5% vs. non-HBCU 2.6%, p=0.011 and chair (mean HBCU 73.1% vs. non-HBCU 2.2%, p≤0.001 positions. PR designation was associated with increased faculty (mean PR 75.40% vs. non-PR 3.72%, p≤0.001 and chair (mean PR 75.00% vs. non-PR 3.54%, p≤0.001 positions filled by Latinos/Hispanics. Conclusions: Women and African Americans are better represented in faculty and leadership positions at HBCU, and women and Latino/Hispanics at PR medical schools, than they are at allopathic peer institutions.

The black Arab as a substitution for sin and guilt

Directory of Open Access Journals (Sweden)

Petrović Radmilo

2009-01-01

Full Text Available The figure of the Black Arab as a form of guilt and sin is a well-established memorial pattern throughout the Mediterranean world, having already existed for more than 3000 years. This text is focused on two different types of interpretation of the Black Stone and its semantic relation with the symbolized figure of Black Arab in the oral traditions of Mediterranean peoples - Jewish religion and Islamic eschatology. The transformation of the signification of the Black Stone was transferred to the Islamic religion in the act of pilgrimage. The Jewish practice of transferring sin and guilt is related with the Iranian-Manichean Ahura Mazda-Ahriman, and the ancient Greek goddess Hecate. All manifestations of the Black Arab left a deep trace on Slavic spiritual life through the Slavic gods Chernobog, Triglav and Toyan and consequently on the deeply rooted conception of all Slavic peoples that the Black Arab was a black demon of death and the underworld.

Survival advantage in black versus white men with CKD: effect of estimated GFR and case mix.

Science.gov (United States)

Kovesdy, Csaba P; Quarles, L Darryl; Lott, Evan H; Lu, Jun Ling; Ma, Jennie Z; Molnar, Miklos Z; Kalantar-Zadeh, Kamyar

2013-08-01

Black dialysis patients have significantly lower mortality compared with white patients, in contradistinction to the higher mortality seen in blacks in the general population. It is unclear whether a similar paradox exists in patients with non-dialysis-dependent chronic kidney disease (CKD), and if it does, what its underlying reasons are. Historical cohort. 518,406 white and 52,402 black male US veterans with non-dialysis-dependent CKD stages 3-5. Black race. We examined overall and CKD stage-specific all-cause mortality using parametric survival models. The effect of sociodemographic characteristics, comorbid conditions, and laboratory characteristics on the observed differences was explored in multivariable models. During a median follow-up of 4.7 years, 172,093 patients died (mortality rate, 71.0 [95% CI, 70.6-71.3] per 1,000 patient-years). Black race was associated with significantly lower crude mortality (HR, 0.95; 95% CI, 0.94-0.97; P case-mix and laboratory characteristics occurring during the course of kidney disease. Published by Elsevier Inc. on behalf of the National Kidney Foundation, Inc.

Clustering of 18 Local Black Rice Base on Total Anthocyanin

Directory of Open Access Journals (Sweden)

Kristamtini Kristamtini

2017-10-01

Full Text Available Black rice has a high anthocyanin content in the pericarp layer, which provides a dark purple color. Anthocyanin serve as an antioxidant that control cholesterol level in the blood, prevent anemia, potentially improve the body's resistance to disease, improve damage to liver cells (hepatitis and chirrosis, prevent impaired kidney function, prevent cancer/tumors, slows down antiaging, and prevent atherosclerosis and cardiovascular disease. Exploration results at AIAT Yogyakarta, Indonesia from 2011 to 2014 obtained 18 cultivar of local black rice Indonesia. The names of the rice are related to the color (black, red or purple formed by anthocyanin deposits in the pericarp layer, seed coat or aleuron. The objective of the study was to classify several types of local black rice from explorations based on the total anthocyanin content. The study was conducted by clustering analyzing the total anthocyanin content of 18 local black rice cultivars in Indonesia. Cluster analysis of total anthocyanin content were done using SAS ver. 9.2. Clustering dendogram shows that there were 4 groups of black rice cultivars based on the total anthocyanin content. Group I consists of Melik black rice, Patalan black rice, Yunianto black rice, Muharjo black rice, Ngatijo black rice, short life of Tugiyo black rice, Andel hitam 1, Jlitheng, and Sragen black rice. Group II consists of Pari ireng, Magelang black hairy rice, Banjarnegara-Wonosobo black rice, and Banjarnegara black rice. Group III consists of NTT black rice, Magelang non hairy black rice, Sembada hitam, and longevity Tugiyo black rice. Group IV consist only one type of black rice namely Cempo ireng. The grouping result indicate the existence of duplicate names among the black rice namely Patalan with Yunianto black rice, and short life Tugiyo with Andel hitam 1 black rice.

Inside and outside stories of black-branes in anti de Sitter space

International Nuclear Information System (INIS)

Hansen, Jakob; Lee, Bum-Hoon; Park, Chanyong; Yeom, Dong-han

2013-01-01

In this paper, we investigate the dynamics inside and outside of black-branes in anti de Sitter space by numerical simulations using double-null formalism. We prepare a charged planar matter shell which, due to a negative cosmological constant, collapses and dynamically forms a black-brane with an apparent horizon, a singularity and a Cauchy horizon. The gravitational collapse cannot form a naked overcharged black-brane and hence weak cosmic censorship is safe. Although mass inflation occurs, the effect is much milder than in the case of charged black holes; hence, strong cosmic censorship seems not to be safe. We observed the scalar field dynamics outside the horizon. There should remain a non-trivial scalar field combination—‘charge cloud’—between the horizon and the boundary. This can give some meaning in terms of the AdS/CFT correspondence. (paper)

Validation of inverse seasonal peak mortality in medieval plagues, including the Black Death, in comparison to modern Yersinia pestis-variant diseases.

Science.gov (United States)

Welford, Mark R; Bossak, Brian H

2009-12-22

Recent studies have noted myriad qualitative and quantitative inconsistencies between the medieval Black Death (and subsequent "plagues") and modern empirical Y. pestis plague data, most of which is derived from the Indian and Chinese plague outbreaks of A.D. 1900+/-15 years. Previous works have noted apparent differences in seasonal mortality peaks during Black Death outbreaks versus peaks of bubonic and pneumonic plagues attributed to Y. pestis infection, but have not provided spatiotemporal statistical support. Our objective here was to validate individual observations of this seasonal discrepancy in peak mortality between historical epidemics and modern empirical data. We compiled and aggregated multiple daily, weekly and monthly datasets of both Y. pestis plague epidemics and suspected Black Death epidemics to compare seasonal differences in mortality peaks at a monthly resolution. Statistical and time series analyses of the epidemic data indicate that a seasonal inversion in peak mortality does exist between known Y. pestis plague and suspected Black Death epidemics. We provide possible explanations for this seasonal inversion. These results add further evidence of inconsistency between historical plagues, including the Black Death, and our current understanding of Y. pestis-variant disease. We expect that the line of inquiry into the disputed cause of the greatest recorded epidemic will continue to intensify. Given the rapid pace of environmental change in the modern world, it is crucial that we understand past lethal outbreaks as fully as possible in order to prepare for future deadly pandemics.

Black holes

International Nuclear Information System (INIS)

Feast, M.W.

1981-01-01

This article deals with two questions, namely whether it is possible for black holes to exist, and if the answer is yes, whether we have found any yet. In deciding whether black holes can exist or not the central role in the shaping of our universe played by the forse of gravity is discussed, and in deciding whether we are likely to find black holes in the universe the author looks at the way stars evolve, as well as white dwarfs and neutron stars. He also discusses the problem how to detect a black hole, possible black holes, a southern black hole, massive black holes, as well as why black holes are studied

Varying constants, black holes, and quantum gravity

International Nuclear Information System (INIS)

Carlip, S.

2003-01-01

Tentative observations and theoretical considerations have recently led to renewed interest in models of fundamental physics in which certain 'constants' vary in time. Assuming fixed black hole mass and the standard form of the Bekenstein-Hawking entropy, Davies, Davis and Lineweaver have argued that the laws of black hole thermodynamics disfavor models in which the fundamental electric charge e changes. I show that with these assumptions, similar considerations severely constrain 'varying speed of light' models, unless we are prepared to abandon cherished assumptions about quantum gravity. Relaxation of these assumptions permits sensible theories of quantum gravity with ''varying constants,'' but also eliminates the thermodynamic constraints, though the black hole mass spectrum may still provide some restrictions on the range of allowable models

From Pinholes to Black Holes

Energy Technology Data Exchange (ETDEWEB)

Fenimore, Edward E. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

2014-10-06

Pinhole photography has made major contributions to astrophysics through the use of “coded apertures”. Coded apertures were instrumental in locating gamma-ray bursts and proving that they originate in faraway galaxies, some from the birth of black holes from the first stars that formed just after the big bang.

Racism in the form of micro aggressions and the risk of preterm birth among Black women

Science.gov (United States)

Slaughter-Acey, Jaime C.; Sealy-Jefferson, Shawnita; Helmkamp, Laura; Caldwell, Cleopatra H; Osypuk, Theresa L.; Platt, Robert W.; Straughen, Jennifer K.; Dailey-Okezie, Rhonda K.; Abeysekara, Purni; Misra, Dawn P.

2015-01-01

Purpose This study sought to examine whether perceived interpersonal racism in the form of racial micro aggressions was associated with preterm birth (PTB) and whether the presence of depressive symptoms and perceived stress modified the association. Methods Data stem from a cohort of 1410 Black women residing in Metropolitan Detroit, Michigan enrolled into the Life-course Influences on Fetal Environments (LIFE) Study. The Daily Life Experiences of Racism and Bother (DLE-B) scale measured the frequency and perceived stressfulness of racial micro aggressions experienced during the past year. Severe past-week depressive symptomatology was measured by the Centers for Epidemiologic Studies-Depression scale (CES-D) dichotomized at ≥23. Restricted cubic splines were used to model non-linearity between perceived racism and PTB. We used the Perceived Stress Scale (PSS) to assess general stress perceptions. Results Stratified spline regression analysis demonstrated that among those with severe depressive symptoms, perceived racism was not associated with PTB. However, perceived racism was significantly associated with PTB among women with mild to moderate (CES-D score ≤22) depressive symptoms. Perceived racism was not associated with PTB among women with or without high amounts of perceived stress. Conclusions Our findings suggest that racism, at least in the form of racial micro aggressions, may not further impact a group already at high risk for PTB (those with severe depressive symptoms), but may increase the risk of PTB for women at lower baseline risk. PMID:26549132

Racism in the form of micro aggressions and the risk of preterm birth among black women.

Science.gov (United States)

Slaughter-Acey, Jaime C; Sealy-Jefferson, Shawnita; Helmkamp, Laura; Caldwell, Cleopatra H; Osypuk, Theresa L; Platt, Robert W; Straughen, Jennifer K; Dailey-Okezie, Rhonda K; Abeysekara, Purni; Misra, Dawn P

2016-01-01

This study sought to examine whether perceived interpersonal racism in the form of racial micro aggressions was associated with preterm birth (PTB) and whether the presence of depressive symptoms and perceived stress modified the association. Data stem from a cohort of 1410 black women residing in Metropolitan Detroit, Michigan, enrolled into the Life-course Influences on Fetal Environments (LIFE) study. The Daily Life Experiences of Racism and Bother (DLE-B) scale measured the frequency and perceived stressfulness of racial micro aggressions experienced during the past year. Severe past-week depressive symptomatology was measured by the Centers for Epidemiologic Studies-Depression scale (CES-D) dichotomized at ≥ 23. Restricted cubic splines were used to model nonlinearity between perceived racism and PTB. We used the Perceived Stress Scale to assess general stress perceptions. Stratified spline regression analysis demonstrated that among those with severe depressive symptoms, perceived racism was not associated with PTB. However, perceived racism was significantly associated with PTB among women with mild to moderate (CES-D score ≤ 22) depressive symptoms. Perceived racism was not associated with PTB among women with or without high amounts of perceived stress. Our findings suggest that racism, at least in the form of racial micro aggressions, may not further impact a group already at high risk for PTB (those with severe depressive symptoms), but may increase the risk of PTB for women at lower baseline risk. Copyright © 2016 Elsevier Inc. All rights reserved.

The Impact of Religious Faith and Internalized Homonegativity on Resiliency for Black Lesbian, Gay, and Bisexual Emerging Adults

Science.gov (United States)

Walker, Ja'Nina J.; Longmire-Avital, Buffie

2013-01-01

Religious faith has been instrumental in fostering positive mental health outcomes for historically disenfranchised populations, such as Black Americans. However, the religious institutional devaluing of same-sex behavior and identity fuels internalized homonegativity (i.e., negative thoughts regarding one's same-sex sexual behavior) for…

Black silicon with black bus-bar strings

DEFF Research Database (Denmark)

Davidsen, Rasmus Schmidt; Tang, Peter Torben; Mizushima, Io

2016-01-01

We present the combination of black silicon texturing and blackened bus-bar strings as a potential method for obtaining all-black solar panels, while using conventional, front-contacted solar cells. Black silicon was realized by mask-less reactive ion etching resulting in total, average reflectance...... below 0.5% across a 156x156 mm2 silicon wafer. Black bus-bars were realized by oxidized copper resulting in reflectance below 3% in the entire visible wavelength range. The combination of these two technologies may result in aesthetic, all-black panels based on conventional, front-contacted solar cells...

Selections from 2016: Primordial Black Holes as Dark Matter

Science.gov (United States)

Kohler, Susanna

2016-12-01

Editors note:In these last two weeks of 2016, well be looking at a few selections that we havent yet discussed on AAS Nova from among the most-downloaded paperspublished in AAS journals this year. The usual posting schedule will resume after the AAS winter meeting.LIGO Gravitational Wave Detection, Primordial Black Holes, and the Near-IR Cosmic Infrared Background AnisotropiesPublished May2016Main takeaway:A study by Alexander Kashlinsky (NASA Goddard SFC) proposes that the cold dark matter that makes up the majority of the universes matter may be made of black holes. These black holes, Kashlinsky suggests, are primordial: they collapsed directly from dense regions of the universe soon after the Big Bang.Why its interesting:This model would simultaneously explain several observations. In particular, we see similarities in patterns between the cosmic infrared and X-ray backgrounds. This would make sense if accretion onto primordial black holes in halos produced the X-ray background in the same regions where the first stars also formed, producing the infrared background.What this means for current events:In Kashlinskys model, primordial black holes would occasionally form binary pairs and eventually spiral in and merge. The release of energy from such an event would then be observable by gravitational-wave detectors. Could the gravitational-wave signal that LIGO detected last year have been two primordial black holes merging? More observations will be needed to find out.CitationA. Kashlinsky 2016 ApJL 823 L25. doi:10.3847/2041-8205/823/2/L25

Primordial Black Holes from First Principles (Overview)

Science.gov (United States)

Lam, Casey; Bloomfield, Jolyon; Moss, Zander; Russell, Megan; Face, Stephen; Guth, Alan

2017-01-01

Given a power spectrum from inflation, our goal is to calculate, from first principles, the number density and mass spectrum of primordial black holes that form in the early universe. Previously, these have been calculated using the Press- Schechter formalism and some demonstrably dubious rules of thumb regarding predictions of black hole collapse. Instead, we use Monte Carlo integration methods to sample field configurations from a power spectrum combined with numerical relativity simulations to obtain a more accurate picture of primordial black hole formation. We demonstrate how this can be applied for both Gaussian perturbations and the more interesting (for primordial black holes) theory of hybrid inflation. One of the tools that we employ is a variant of the BBKS formalism for computing the statistics of density peaks in the early universe. We discuss the issue of overcounting due to subpeaks that can arise from this approach (the ``cloud-in-cloud'' problem). MIT UROP Office- Paul E. Gray (1954) Endowed Fund.

Educating Our Own: The Historical Legacy of HBCUs and Their Relevance for Educating a New Generation of Leaders

Science.gov (United States)

Albritton, Travis J.

2012-01-01

Providing a brief history of historically Black colleges and universities (HBCUs)--including how and why they were founded, funding sources and needs over time, and an examination of mission statements--the author considers the relevance of HBCUs in the current twenty-first century context. He makes an argument that the educational opportunities…

The Semantics of White and Black in Italian and Spanish Phraseology

Directory of Open Access Journals (Sweden)

Daša Stanič

2012-12-01

Full Text Available This article considers the semantic values of "white" and "black" in Italian and Spanish phraseology. These two colors are among all those that form the greatest number of phraseological units. Consulting Italian and Spanish dictionaries, bilingual dictionaries, phraseological dictionaries and chosen corpora of the two languages, 232 phraseological units with "white" and "black" were found. The most common type are collocations of the type adjective plus noun. In this paper, the phraseological units are classified according to their semantic values. It has been discovered that while the semantic values of "white" can in both languages be positive (in the majority and negative, the values of "black" are almost all negative. Variants of phraseological units that can be formed with both colours as well as examples of phraseological units containing both colours were highlighted. In most of these examples the "white" and "black" represent the opposite. Only a few phraseological units with "white" and "black" directly linked to the Italian and Spanish culture were found. They refer to mafia, football, fascism and bullfighting.

Black American Literature and the Problem of Racism, Slavery and ...

African Journals Online (AJOL)

The problem created by racism could be traced to be the major factor behind most Black literature through the ages. In America, this gave rise to a new form of literary expression known as the Black American Literature or African American Literature. The main concern of this sub-genre of literature is to redeem the face of ...

Cosmic censorship principle in two-dimensional charged extreme black hole

Energy Technology Data Exchange (ETDEWEB)

Wang Bin; Ru Keng Su [Fudan Univ., Shanghai (China). Dept. of Physics; Cheung, T. [Hong Kong City Univ., Hong Kong (China). Dept. of Physics

1999-10-01

By constructing a gedanken experiment, the authors prove that the event horizon of a two-dimensional charged extreme black hole cannot be removed. Singularities are found to be formed on the horizon through analyzing the fate of Hawking partner and application of Helliwell-Konkowski conjecture. The cosmic censorship principle is well protected in this black hole.

Theological training in the black Reformed Churches in South Africa (RCSA

Directory of Open Access Journals (Sweden)

Hulisani Ramantswana

2015-03-01

Full Text Available This article presents a historic analysis of theological training in the black Reformed Churches in South Africa (RCSA − Southland Synod (Coloured, Synod Midlands (black and Synod Soutpansberg (black − and highlights the major trends with regard to theological training. Four phases are identified: (1 1910–1951, informal training of evangelists and ministers on a local basis; (2 1952–1960, the beginning of formal training of ministers and evangelists; (3 1961–1989, training under the 1961 Theological Training Policy for the black RCSA; and (4 1990 to today, theological training in the black RCSA in the context of the new South Africa. Teologiese opleiding in die swart Gereformeerde Kerke in Suid-Afrika (GKSA. Die artikel bied ’n historiese ontleding van teologiese opleiding in die swart Gereformeerde Kerke in Suid-Afrika − Suidland Sinode (Kleurling, Middellande Sinode (swart en Soutpansberg Sinode (swart − en beklemtoon die belangrikste tendense met betrekking tot teologiese opleiding. Vier fases word in die artikel geïdentifiseer: (1 1910–1951, informele opleiding van evangeliste en leraars op ’n plaaslike basis; (2 1952–1960, die begin van die formele opleiding van predikante en evangeliste; (3 1961–1989, opleiding onder die 1961 Teologiese Opleidingsbeleid in die swart GKSA; en (4 1990 tot vandag, teologiese opleiding in die swart GKSA in die konteks van die nuwe Suid-Afrika.

Patterns in Nuclear and Mitochondrial DNA Reveal Historical and Recent Isolation in the Black-Tailed Godwit (

NARCIS (Netherlands)

Trimbos, K.B.; Doorenweerd, C.; Kraaijeveld, K.; Musters, C.J.M.; Groen, N.M.; de Knijff, P.; Piersma, T.; de Snoo, G.R.

2014-01-01

On the basis of morphological differences, three subspecies of Black-tailed Godwit (Limosa limosa) have been recognized (L. l. limosa, L. l. islandica and L. l. melanuroides). In previous studies mitochondrial DNA (mtDNA) sequence data showed minimal genetic divergence between the three subspecies

Visualizing, Approximating, and Understanding Black-Hole Binaries

Science.gov (United States)

Nichols, David A.

Numerical-relativity simulations of black-hole binaries and advancements in gravitational-wave detectors now make it possible to learn more about the collisions of compact astrophysical bodies. To be able to infer more about the dynamical behavior of these objects requires a fuller analysis of the connection between the dynamics of pairs of black holes and their emitted gravitational waves. The chapters of this thesis describe three approaches to learn more about the relationship between the dynamics of black-hole binaries and their gravitational waves: modeling momentum flow in binaries with the Landau-Lifshitz formalism, approximating binary dynamics near the time of merger with post-Newtonian and black-hole-perturbation theories, and visualizing spacetime curvature with tidal tendexes and frame-drag vortexes. In Chapters 2--4, my collaborators and I present a method to quantify the flow of momentum in black-hole binaries using the Landau-Lifshitz formalism. Chapter 2 reviews an intuitive version of the formalism in the first-post-Newtonian approximation that bears a strong resemblance to Maxwell's theory of electromagnetism. Chapter 3 applies this approximation to relate the simultaneous bobbing motion of rotating black holes in the superkick configuration---equal-mass black holes with their spins anti-aligned and in the orbital plane---to the flow of momentum in the spacetime, prior to the black holes' merger. Chapter 4 then uses the Landau-Lifshitz formalism to explain the dynamics of a head-on merger of spinning black holes, whose spins are anti-aligned and transverse to the infalling motion. Before they merge, the black holes move with a large, transverse, velocity, which we can explain using the post-Newtonian approximation; as the holes merge and form a single black hole, we can use the Landau-Lifshitz formalism without any approximations to connect the slowing of the final black hole to its absorbing momentum density during the merger. In Chapters 5

The physical drivers of historical and 21st century global precipitation changes

International Nuclear Information System (INIS)

Thorpe, Livia; Andrews, Timothy

2014-01-01

Historical and 21st century global precipitation changes are investigated using data from the fifth Coupled Model Intercomparison Project (CMIP5) Atmosphere-Ocean-General-Circulation-Models (AOGCMs) and a simple energy-balance model. In the simple model, precipitation change in response to a given top-of-atmosphere radiative forcing is calculated as the sum of a response to the surface warming and a direct ‘adjustment’ response to the atmospheric radiative forcing. This simple model allows the adjustment in global mean precipitation to atmospheric radiative forcing from different forcing agents to be examined separately and emulates the AOGCMs well. During the historical period the AOGCMs simulate little global precipitation change despite an increase in global temperature—at the end of the historical period, global multi-model mean precipitation has increased by about 0.03 mm day −1 , while the global multi-model mean surface temperature has warmed by about 1 K, both relative to the pre-industrial control means. This is because there is a large direct effect from CO 2 and black carbon atmospheric forcing that opposes the increase in precipitation from surface warming. In the 21st century scenarios, the opposing effect from black carbon declines and the increase in global precipitation due to surface warming dominates. The cause of the spread between models in the global precipitation projections (which can be up to 0.25 mm day −1 ) is examined and found to come mainly from uncertainty in the climate sensitivity. The spatial distribution of precipitation change is found to be dominated by the response to surface warming. It is concluded that AOGCM global precipitation projections are in line with expectations based on our understanding of how the energy and water cycles are physically linked. (letters)

Black rings

International Nuclear Information System (INIS)

Emparan, Roberto; Reall, Harvey S

2006-01-01

A black ring is a five-dimensional black hole with an event horizon of topology S 1 x S 2 . We provide an introduction to the description of black rings in general relativity and string theory. Novel aspects of the presentation include a new approach to constructing black ring coordinates and a critical review of black ring microscopics. (topical review)

"Black Like Me": Reframing Blackness for Decolonial Politics

Science.gov (United States)

Dei, George J. Sefa

2018-01-01

From a particular vantage point, as an African-born scholar with a politics to affirm my Black subjectivity and Indigeneity in a diasporic context, my article engages a (re)theorization of Blackness for decolonial politics. Building on existing works of how Black scholars, themselves, have theorized Blackness, and recognizing the fluid,…

Interacting black holes on the brane: the seeding of binaries

International Nuclear Information System (INIS)

Majumdar, A.S.; Mehta, Anita; Luck, J.M.

2005-01-01

We consider the evolution of subhorizon-sized black holes which are formed during the high energy phase of the braneworld scenario. These black holes are long-lived due to modified evaporation and accretion of radiation during the radiation dominated era. We argue that an initial mass difference between any two neighbouring black holes is always amplified because of their exchange of energy with the surrounding radiation. We present a scheme of binary formation based on mass differences suggesting that such a scenario could lead to binaries with observable signatures

The mass formula for an exotic BTZ black hole

Energy Technology Data Exchange (ETDEWEB)

Zhang, Baocheng, E-mail: zhangbc.zhang@yahoo.com

2016-04-15

An exotic Bañados–Teitelboim–Zanelli (BTZ) black hole has an angular momentum larger than its mass in three dimension (3D), which suggests the possibility that cosmic censorship could be violated if angular momentum is extracted by the Penrose process. In this paper, we propose a mass formula for the exotic BTZ black hole and show no violation of weak cosmic censorship in the gedanken process above by understanding properly its mass formula. Unlike the other black holes, the total energy of the exotic BTZ black hole is represented by the angular momentum instead of the mass, which supports a basic point of view that the same geometry should be determined by the same energy in 3D general relativity whose equation of motion can be given either by normal 3D Einstein gravity or by exotic 3D Einstein gravity. However, only the mass of the exotic black hole is related to the thermodynamics and other forms of energy are “dumb”, which is consistent with the earlier thermodynamic analysis about exotic black holes.

The mass formula for an exotic BTZ black hole

International Nuclear Information System (INIS)

Zhang, Baocheng

2016-01-01

An exotic Bañados–Teitelboim–Zanelli (BTZ) black hole has an angular momentum larger than its mass in three dimension (3D), which suggests the possibility that cosmic censorship could be violated if angular momentum is extracted by the Penrose process. In this paper, we propose a mass formula for the exotic BTZ black hole and show no violation of weak cosmic censorship in the gedanken process above by understanding properly its mass formula. Unlike the other black holes, the total energy of the exotic BTZ black hole is represented by the angular momentum instead of the mass, which supports a basic point of view that the same geometry should be determined by the same energy in 3D general relativity whose equation of motion can be given either by normal 3D Einstein gravity or by exotic 3D Einstein gravity. However, only the mass of the exotic black hole is related to the thermodynamics and other forms of energy are “dumb”, which is consistent with the earlier thermodynamic analysis about exotic black holes.

Polyextremotolerant black fungi: oligotrophism, adaptive potential and a link to lichen symbioses

Directory of Open Access Journals (Sweden)

Cene eGostinčar

2012-11-01

Full Text Available Black meristematic fungi can survive high doses of radiation and are resistant to desiccation. These adaptations help them to colonize harsh oligotrophic habitats, e.g. on the surface and subsurface of rocks. One of their most characteristic stress-resistance mechanisms is the accumulation of melanin in the cell walls. This, production of other protective molecules and a plastic morphology further contribute to ecological flexibility of black fungi. Increased growth rates of some species after exposure to ionizing radiation even suggest yet unknown mechanisms of energy production. Other unusual metabolic strategies may include harvesting UV or visible light or gaining energy by forming facultative lichen-like associations with algae or cyanobacteria. The latter is not entirely surprising, since certain black fungal lineages are phylogenetically related to clades of lichen-forming fungi. Similar to black fungi, lichen-forming fungi are adapted to growth on exposed surfaces with low availability of nutrients. They also efficiently use protective molecules to tolerate frequent periods of extreme stress. Traits shared by both groups of fungi may have been important in facilitating the evolution and radiation of lichen-symbioses.

On the gravitational wave background from black hole binaries after the first LIGO detections

Energy Technology Data Exchange (ETDEWEB)

Cholis, Ilias, E-mail: icholis1@jhu.edu [Department of Physics and Astronomy, The Johns Hopkins University, Baltimore, Maryland, 21218 (United States)

2017-06-01

The detection of gravitational waves from the merger of binary black holes by the LIGO Collaboration has opened a new window to astrophysics. With the sensitivities of ground based detectors in the coming years, we will principally detect local binary black hole mergers. The integrated merger rate can instead be probed by the gravitational-wave background, the incoherent superposition of the released energy in gravitational waves during binary-black-hole coalescence. Through that, the properties of the binary black holes can be studied. In this work we show that by measuring the energy density Ω{sub GW} (in units of the cosmic critical density) of the gravitational-wave background, we can search for the rare ∼ 100 M {sub ⊙} massive black holes formed in the Universe. In addition, we can answer how often the least massive BHs of mass ≳ 3 M {sub ⊙} form. Finally, if there are multiple channels for the formation of binary black holes and if any of them predicts a narrow mass range for the black holes, then the total Ω{sub GW} spectrum may have features that with the future Einstein Telescope can be detected.

5D black hole solution in Einstein-Yang-Mills-Gauss-Bonnet theory

International Nuclear Information System (INIS)

Mazharimousavi, S. Habib; Halilsoy, M.

2007-01-01

By adopting the 5D version of the Wu-Yang ansatz we present in closed form a black hole solution in the Einstein-Yang-Mills-Gauss-Bonnet theory. In the Einstein-Yang-Mills limit, we recover the 5D black hole solution already known

The stony road we tread: The challenges and contributions of Black Liberation Theology in post-apartheid South Africa

Directory of Open Access Journals (Sweden)

Mothoagae, Itumeleng Daniel

2012-06-01

Full Text Available The Great Trek of 1838 brought about a belief in the supremacy of the Dutch descendants in South Africa. Their 1948 election victory authenticated for them their interpretation of theology and their historical experiences of Gods involvement in their lives. Black Theology challenged the perception of Afrikaner supremacy and their theological hegemony, although Mosala argued against the blindness of black theologians in their criticism of white theology because they were actually using the same tools of analysis that whites had traditionally used to justify their case (Mosala and Tlhagale 1986:175196. Mosala . This article discusses a paper presented at a conference in Cairo by Takatso Mofokeng on the issue of land, and further outlines the challenges and contributions of Black Theology today.

Mass and free energy of Lovelock black holes

International Nuclear Information System (INIS)

Kastor, David; Traschen, Jennie; Ray, Sourya

2011-01-01

An explicit formula for the ADM mass of an asymptotically AdS black hole in a generic Lovelock gravity theory is presented, identical in form to that in Einstein gravity, but multiplied by a function of the Lovelock coupling constants and the AdS curvature radius. A Gauss' law-type formula relates the mass, which is an integral at infinity, to an expression depending instead on the horizon radius. This and other thermodynamic quantities, such as the free energy, are then analyzed in the limits of small and large horizon radius, yielding results that are independent of the detailed choice of Lovelock couplings. In even dimensions, the temperature diverges in both limits, implying the existence of a minimum temperature for black holes. The negative free energy of sufficiently large black holes implies the existence of a Hawking-Page transition. In odd dimensions, the temperature still diverges for large black holes, which again have negative free energy. However, the temperature vanishes as the horizon radius tends to zero and sufficiently small black holes have positive specific heat.

Black-Hole Binaries, Gravitational Waves, and Numerical Relativity

Science.gov (United States)

Kelly, Bernard J.; Centrella, Joan; Baker, John G.; Kelly, Bernard J.; vanMeter, James R.

2010-01-01

Understanding the predictions of general relativity for the dynamical interactions of two black holes has been a long-standing unsolved problem in theoretical physics. Black-hole mergers are monumental astrophysical events ' releasing tremendous amounts of energy in the form of gravitational radiation ' and are key sources for both ground- and spacebased gravitational wave detectors. The black-hole merger dynamics and the resulting gravitational waveforms can only he calculated through numerical simulations of Einstein's equations of general relativity. For many years, numerical relativists attempting to model these mergers encountered a host of problems, causing their codes to crash after just a fraction of a binary orbit cnuld be simulated. Recently ' however, a series of dramatic advances in numerical relativity has ' for the first time, allowed stable / robust black hole merger simulations. We chronicle this remarkable progress in the rapidly maturing field of numerical relativity, and the new understanding of black-hole binary dynamics that is emerging. We also discuss important applications of these fundamental physics results to astrophysics, to gravitationalwave astronomy, and in other areas.

A new form of the rotating C-metric

International Nuclear Information System (INIS)

Hong, Kenneth; Teo, Edward

2005-01-01

In a previous paper, we showed that the traditional form of the charged C-metric can be transformed, by a change of coordinates, into one with an explicitly factorizable structure function. This new form of the C-metric has the advantage that its properties become much simpler to analyse. In this paper, we propose an analogous new form for the rotating charged C-metric, with structure function G(ξ) = (1 - ξ 2 )(1 + r + Aξ)(1 + r - Aξ), where r ± are the usual locations of the horizons in the Kerr-Newman black hole. Unlike the non-rotating case, this new form is not related to the traditional one by a coordinate transformation. We show that the physical distinction between these two forms of the rotating C-metric lies in the nature of the conical singularities causing the black holes to accelerate apart: the new form is free of torsion singularities and therefore does not contain any closed timelike curves. We claim that this new form should be considered the natural generalization of the C-metric with rotation

Feeding supermassive black holes by collisional cascades

Science.gov (United States)

Faber, Christian; Dehnen, Walter

2018-05-01

The processes driving gas accretion on to supermassive black holes (SMBHs) are still poorly understood. Angular momentum conservation prevents gas within ˜10 pc of the black hole from reaching radii ˜10-3 pc where viscous accretion becomes efficient. Here we present simulations of the collapse of a clumpy shell of swept-up isothermal gas, which is assumed to have formed as a result of feedback from a previous episode of AGN activity. The gas falls towards the SMBH forming clumps and streams, which intersect, collide, and often form a disc. These collisions promote partial cancellations of angular momenta, resulting in further infall and more collisions. This continued collisional cascade generates a tail of gas with sufficiently small angular momenta and provides a viable route for gas inflow to sub-parsec scales. The efficiency of this process hardly depends on details, such as gas temperature, initial virial ratio and power spectrum of the gas distribution, as long as it is not strongly rotating. Adding star formation to this picture might explain the near-simultaneous formation of the S-stars (from tidally disrupted binaries formed in plunging gas streams) and the sub-parsec young stellar disc around Sgr A⋆.

Selection and properties of alternative forming fluids for TRISO fuel kernel production

Energy Technology Data Exchange (ETDEWEB)

Baker, M.P. [Colorado School of Mines, 1500 Illinois St., Golden, CO 80401 (United States); King, J.C., E-mail: kingjc@mines.edu [Colorado School of Mines, 1500 Illinois St., Golden, CO 80401 (United States); Gorman, B.P. [Colorado School of Mines, 1500 Illinois St., Golden, CO 80401 (United States); Marshall, D.W. [Idaho National Laboratory, 2525 N. Fremont Avenue, P.O. Box 1625, Idaho Falls, ID 83415 (United States)

2013-01-15

Highlights: Black-Right-Pointing-Pointer Forming fluid selection criteria developed for TRISO kernel production. Black-Right-Pointing-Pointer Ten candidates selected for further study. Black-Right-Pointing-Pointer Density, viscosity, and surface tension measured for first time. Black-Right-Pointing-Pointer Settling velocity and heat transfer rates calculated. Black-Right-Pointing-Pointer Three fluids recommended for kernel production testing. - Abstract: Current Very High Temperature Reactor (VHTR) designs incorporate TRi-structural ISOtropic (TRISO) fuel, which consists of a spherical fissile fuel kernel surrounded by layers of pyrolytic carbon and silicon carbide. An internal sol-gel process forms the fuel kernel using wet chemistry to produce uranium oxyhydroxide gel spheres by dropping a cold precursor solution into a hot column of trichloroethylene (TCE). Over time, gelation byproducts inhibit complete gelation, and the TCE must be purified or discarded. The resulting TCE waste stream contains both radioactive and hazardous materials and is thus considered a mixed hazardous waste. Changing the forming fluid to a non-hazardous alternative could greatly improve the economics of TRISO fuel kernel production. Selection criteria for a replacement forming fluid narrowed a list of {approx}10,800 chemicals to yield ten potential replacement forming fluids: 1-bromododecane, 1-bromotetradecane, 1-bromoundecane, 1-chlorooctadecane, 1-chlorotetradecane, 1-iododecane, 1-iodododecane, 1-iodohexadecane, 1-iodooctadecane, and squalane. The density, viscosity, and surface tension for each potential replacement forming fluid were measured as a function of temperature between 25 Degree-Sign C and 80 Degree-Sign C. Calculated settling velocities and heat transfer rates give an overall column height approximation. 1-bromotetradecane, 1-chlorooctadecane, and 1-iodododecane show the greatest promise as replacements, and future tests will verify their ability to form satisfactory

Can the graviton have a large mass near black holes?

Science.gov (United States)

Zhang, Jun; Zhou, Shuang-Yong

2018-04-01

The mass of the graviton, if nonzero, is usually considered to be very small, e.g., of the Hubble scale, from several observational constraints. In this paper, we propose a gravity model where the graviton mass is very small in the usual weak gravity environments, below all the current graviton mass bounds, but becomes much larger in the strong gravity regime such as a black hole's vicinity. For black holes in this model, significant deviations from general relativity emerge very close to the black hole horizon and alter the black hole quasinormal modes, which can be extracted from the ringdown wave form of black hole binary mergers. Also, the enhancement of the graviton mass near the horizon can result in echoes in the late-time ringdown, which can be verified in the upcoming gravitational wave observations of higher sensitivity.

Probing Primordial Black Hole Dark Matter with Gravitational Waves.

Science.gov (United States)

Kovetz, Ely D

2017-09-29

Primordial black holes (PBHs) have long been suggested as a candidate for making up some or all of the dark matter in the Universe. Most of the theoretically possible mass range for PBH dark matter has been ruled out with various null observations of expected signatures of their interaction with standard astrophysical objects. However, current constraints are significantly less robust in the 20  M_{⊙}≲M_{PBH}≲100  M_{⊙} mass window, which has received much attention recently, following the detection of merging black holes with estimated masses of ∼30  M_{⊙} by LIGO and the suggestion that these could be black holes formed in the early Universe. We consider the potential of advanced LIGO (aLIGO) operating at design sensitivity to probe this mass range by looking for peaks in the mass spectrum of detected events. To quantify the background, which is due to black holes that are formed from dying stars, we model the shape of the stellar-black-hole mass function and calibrate its amplitude to match the O1 results. Adopting very conservative assumptions about the PBH and stellar-black-hole merger rates, we show that ∼5  yr of aLIGO data can be used to detect a contribution of >20  M_{⊙} PBHs to dark matter down to f_{PBH}99.9% confidence level. Combined with other probes that already suggest tension with f_{PBH}=1, the obtainable independent limits from aLIGO will thus enable a firm test of the scenario that PBHs make up all of dark matter.

Primordial black hole and wormhole formation by domain walls

Energy Technology Data Exchange (ETDEWEB)

Deng, Heling; Garriga, Jaume; Vilenkin, Alexander, E-mail: heling.deng@tufts.edu, E-mail: garriga@cosmos.phy.tufts.edu, E-mail: vilenkin@cosmos.phy.tufts.edu [Institute of Cosmology, Tufts University, 574 Boston Ave, Medford, MA, 02155 (United States)

2017-04-01

In theories with a broken discrete symmetry, Hubble sized spherical domain walls may spontaneously nucleate during inflation. These objects are subsequently stretched by the inflationary expansion, resulting in a broad distribution of sizes. The fate of the walls after inflation depends on their radius. Walls smaller than a critical radius fall within the cosmological horizon early on and collapse due to their own tension, forming ordinary black holes. But if a wall is large enough, its repulsive gravitational field becomes dominant much before the wall can fall within the cosmological horizon. In this ''supercritical'' case, a wormhole throat develops, connecting the ambient exterior FRW universe with an interior baby universe, where the exponential growth of the wall radius takes place. The wormhole pinches off in a time-scale comparable to its light-crossing time, and black holes are formed at its two mouths. As discussed in previous work, the resulting black hole population has a wide distribution of masses and can have significant astrophysical effects. The mechanism of black hole formation has been previously studied for a dust-dominated universe. Here we investigate the case of a radiation-dominated universe, which is more relevant cosmologically, by using numerical simulations in order to find the initial mass of a black hole as a function of the wall size at the end of inflation. For large supercritical domain walls, this mass nearly saturates the upper bound according to which the black hole cannot be larger than the cosmological horizon. We also find that the subsequent accretion of radiation satisfies a scaling relation, resulting in a mass increase by about a factor of 2.

Latina and Black Women's Perceptions of the Dietetics Major and Profession

Science.gov (United States)

Whelan, Megan

Racial and ethnic groups remain underrepresented in undergraduate health profession education programs and careers, such as nutrition and dietetics (Sullivan, 2004). Overwhelmingly, 82 percent of dietitians are White, three percent are Latino/Latina, and less than three percent are Black (Commission on Dietetic Registration, 2016). While the calls to increase recruitment of underrepresented minorities are plentiful and federal dollars are allotted to the effort, a critical lens is necessary to investigate the complexity of factors that impact the decision to pursue a career within dietetics. The purpose of this qualitative case study was to investigate how Latina and Black women enrolled in an undergraduate Health Career Opportunity Program (HCOP) narrated and reflected upon the dietetics profession. Through the lens of Critical Race Theory and situated learning, I sought to understand the sociocultural and historical underpinnings that hinder or promote career selection. Data collection methods included participant observation, interviews, artifacts, and reflexive journaling. Data were analyzed using inductive coding techniques. My findings revealed the ways in which Latina and Black women believed dietitians must match the socially constructed role model for body image, physical fitness, and healthy eating to be effective in practice. Using a critical media analysis to confront the stereotypical images of dietitians, the women used cliche messages as a selected discourse to mask perceptions of barriers to the dietetics field. Finally, the women believed a dietitian's professional role was to give diet advice which presented a barrier to the profession. Based on my findings I support early introduction to nutrition science as a means to empower individuals to support their health and the health of their community. Recruitment efforts must explicitly address the culture of dietetics which has embraced the stereotypical image. Collectively, the dietetics field must

Black rings and the physical process version of the first law of thermodynamics

International Nuclear Information System (INIS)

Rogatko, Marek

2005-01-01

We consider the problem of the physical process version of the first law of black ring thermodynamics in n-dimensional Einstein gravity with additional (p+1)-form field strength and dilaton fields. The first order variations of mass, angular momentum and local charge for black ring are derived. From them we prove the physical process version of the first law of thermodynamic for stationary black rings

Black Alcoholism.

Science.gov (United States)

Watts, Thomas D.; Wright, Roosevelt

1988-01-01

Examines some aspects of the problem of alcoholism among Blacks, asserting that Black alcoholism can best be considered in an ecological, environmental, sociocultural, and public health context. Notes need for further research on alcoholism among Blacks and for action to reduce the problem of Black alcoholism. (NB)

Swearing Used in Richard Wright’s Black Boy

OpenAIRE

Giyatmi Giyatmi; Ratih WIjayava; Nunun Tri Widarwati

2017-01-01

This research aims at finding the types of swearing expressions and linguistic forms of English swearing used in Richard Wright's Black Boy. This is a descriptive qualitative research since it describes the phenomena of swearing used in the novel. The data of the research are all the conversations or sentences used swearing in the novel written by Richard Wright namely Black Boy as the main data source. The method of collecting data in this research is observation and teknik lanjut catat. Aft...

SEARCHING FOR URBAN PATTERNS; AN ASSESSMENT OF HISTORIC EDGES AND ITS SURROUNDING CONTEXT: HISTORIC CAIRO AS A CASE STUDY

Directory of Open Access Journals (Sweden)

Nabil Mohareb

2016-07-01

Full Text Available This paper analyzes the urban edges of historic cities. Managing these edges would enhance the success of any intervention projects inside the historic fabric. The paper develops and tests a method of analytical assessment framework that is applicable for quantitative analysis within an urban edge. It is capable of measuring micro and macro levels of analysis of historic urban edges with reference to their spatial configuration. In addition, the paper searches for repetitive spatial configuration patterns. The main case study is Historic Cairo. The paper reveals that there are apparent patterns of cause and effect of both spatial configurations and related activities along the urban edges, forming different type of barriers. The paper discovers the repetitive spatial, architectural, and land-use patterns that exist on various edges. These patterns enable the possibility of learning and acquiring from other successful interventions that have been applied to similar patterns, without being limited to cultural or contextual differences.

Classical black holes: the nonlinear dynamics of curved spacetime.

Science.gov (United States)

Thorne, Kip S

2012-08-03

Numerical simulations have revealed two types of physical structures, made from curved spacetime, that are attached to black holes: tendexes, which stretch or squeeze anything they encounter, and vortexes, which twist adjacent inertial frames relative to each other. When black holes collide, their tendexes and vortexes interact and oscillate (a form of nonlinear dynamics of curved spacetime). These oscillations generate gravitational waves, which can give kicks up to 4000 kilometers per second to the merged black hole. The gravitational waves encode details of the spacetime dynamics and will soon be observed and studied by the Laser Interferometer Gravitational Wave Observatory and its international partners.

Validation of inverse seasonal peak mortality in medieval plagues, including the Black Death, in comparison to modern Yersinia pestis-variant diseases.

Directory of Open Access Journals (Sweden)

Mark R Welford

Full Text Available BACKGROUND: Recent studies have noted myriad qualitative and quantitative inconsistencies between the medieval Black Death (and subsequent "plagues" and modern empirical Y. pestis plague data, most of which is derived from the Indian and Chinese plague outbreaks of A.D. 1900+/-15 years. Previous works have noted apparent differences in seasonal mortality peaks during Black Death outbreaks versus peaks of bubonic and pneumonic plagues attributed to Y. pestis infection, but have not provided spatiotemporal statistical support. Our objective here was to validate individual observations of this seasonal discrepancy in peak mortality between historical epidemics and modern empirical data. METHODOLOGY/PRINCIPAL FINDINGS: We compiled and aggregated multiple daily, weekly and monthly datasets of both Y. pestis plague epidemics and suspected Black Death epidemics to compare seasonal differences in mortality peaks at a monthly resolution. Statistical and time series analyses of the epidemic data indicate that a seasonal inversion in peak mortality does exist between known Y. pestis plague and suspected Black Death epidemics. We provide possible explanations for this seasonal inversion. CONCLUSIONS/SIGNIFICANCE: These results add further evidence of inconsistency between historical plagues, including the Black Death, and our current understanding of Y. pestis-variant disease. We expect that the line of inquiry into the disputed cause of the greatest recorded epidemic will continue to intensify. Given the rapid pace of environmental change in the modern world, it is crucial that we understand past lethal outbreaks as fully as possible in order to prepare for future deadly pandemics.

A demographic comparison of two black bear populations in the Interior Highlands of Arkansas

Science.gov (United States)

Clark, Joseph D.; Smith, Kimberly G.

1994-01-01

The Ozark and Ouachita mountain regions of western Arkansas, collectively known as the Interior Highlands, historically supported large numbers of black bears (Ursus americanus). Indiscriminate killing of bears by early settlers and subsequent habitat reductions due to extensive logging and changes in land use resulted in their decline (Smith et al. 1991). By the late 1940's, bears had been extirpated from both regions (Holder 1951).

Time and Quest of Identity of the African-American Character: George Schuyler's Black No More

Directory of Open Access Journals (Sweden)

Hayder Naji Shanbooj Alolaiwi

2017-04-01

Full Text Available This paper attempts to examine the theme of “passing,” viewed as a metaphor of race that marks a step forward from the painful reality of the Middle Passage to “passing,” as both physical reality and metaphor, and to find out the underlying causes of the passing character in George Schyler's Black No More in the light of social and historical dimensions. The study investigates the aspects of “passing”  manifested by the African-American who is often viewed as an “appendage” to the rest of society, blacks have struggled to attain the success, equality, and overall collective consciousness of the American society, while simultaneously creating and maintaining and identity of their own. Blacks have been and continue to be socially, economically, educationally, and politically disenfranchised and therefore cannot completely find unity within an American system that continuously seeks to reaffirm their inferiority.

AGAPE: the gravitational micro-lensing effect for the search for black matter under the form of MACHOs in direction of the M31 galaxy

International Nuclear Information System (INIS)

Le Du, Yann

2000-01-01

After a presentation of the physical framework and notions of observational cosmology, the author of this research thesis presents the phenomenon of gravitational micro-lensing on which AGAPE (Andromeda Galaxy Amplified Pixel Experiment) is based to detect the possible presence of baryonic black matter under the form of MACHOs (Massive compact halo objects, one of the possible candidates for black matter) within the halo of our galaxy and in that of a far galaxy, M31. He gives a precise description of observations performed by AGAPE at the Pic du Midi between 1994 and 1996. In order to observe M31, a new method has been developed (the pixel method) which is based on the light curve of each pixel of the M31 image. The author then reports the processing of light curves which notably aimed at reducing the discrepancy of points on these curves and at allowing a selection of interesting curves to be performed. He reports the characterisation of the searched signal from these curves, and then discusses the obtained results

Calculating the mass fraction of primordial black holes

International Nuclear Information System (INIS)

Young, Sam; Byrnes, Christian T.; Sasaki, Misao

2014-01-01

We reinspect the calculation for the mass fraction of primordial black holes (PBHs) which are formed from primordial perturbations, finding that performing the calculation using the comoving curvature perturbation R c in the standard way vastly overestimates the number of PBHs, by many orders of magnitude. This is because PBHs form shortly after horizon entry, meaning modes significantly larger than the PBH are unobservable and should not affect whether a PBH forms or not—this important effect is not taken into account by smoothing the distribution in the standard fashion. We discuss alternative methods and argue that the density contrast, Δ, should be used instead as super-horizon modes are damped by a factor k 2 . We make a comparison between using a Press-Schechter approach and peaks theory, finding that the two are in close agreement in the region of interest. We also investigate the effect of varying the spectral index, and the running of the spectral index, on the abundance of primordial black holes

The Relationship between History and Ethics in Ian McEwan’s Black Dogs

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Maryam Sedaghat

2014-06-01

Full Text Available The relationship between history and ethics may seem irrelevant at first; however, these two have been related during the long history of war, violence and mass killing. The need of history to ethics is for saving itself from all the violence and terror. Emmanuel Levinas as a philosopher has tried to define ethics in a way that suits the terrible historical condition of humanity in the twentieth century. In his view, ethics is the infinite responsibility towards other human beings. He defines ‘being’ in relation to the ‘other’ who may be a complete stranger. In this definition a person bears complete responsibility toward the other and should answer the other’s call for help. In Ian McEwan's novel Black Dogs the protagonist is exposed to historical legacies of violence, and develops an ethical consciousness until the end of the novel. Responsibility seems to be a good answer to historical mass killing and violence that is dominant in the world.

Growth of black holes in the interior of rotating neutron stars

DEFF Research Database (Denmark)

Kouvaris, C.; Tinyakov, P.

2014-01-01

Mini-black holes made of dark matter that can potentially form in the interior of neutron stars always have been thought to grow by accreting the matter of the core of the star via a spherical Bondi accretion. However, neutron stars have sometimes significant angular velocities that can...... in principle stall the spherical accretion and potentially change the conclusions derived about the time it takes for black holes to destroy a star. We study the effect of the star rotation on the growth of such black holes and the evolution of the black hole spin. Assuming no mechanisms of angular momentum...... evacuation, we find that even moderate rotation rates can in fact destroy spherical accretion at the early stages of the black hole growth. However, we demonstrate that the viscosity of nuclear matter can alleviate the effect of rotation, making it possible for the black hole to maintain spherical accretion...

Strong deflection gravitational lensing by a modified Hayward black hole