Can Black Holes Decay to Naked Singularities?

We investigate thermodynamic properties of two types of asymptotically anti-de Sitter spacetimes: black holes and singular scalar field spacetimes. We describe the possibility that thermodynamic phase transitions can transform one spacetime into another, suggesting that black holes can radiate to naked singularities.Comment: 5 pages, Essay for 2001 Gravity Research Foundation competition, to appear in IJMP

Black Hole Mergers and Unstable Circular Orbits

We describe recent numerical simulations of the merger of a class of equal mass, non-spinning, eccentric binary black hole systems in general relativity. We show that with appropriate fine-tuning of the initial conditions to a region of parameter space we denote the threshold of immediate merger, the binary enters a phase of close interaction in a near-circular orbit, stays there for an amount of time proportional to logarithmic distance from the threshold in parameter space, then either separates or merges to form a single Kerr black hole. To gain a better understanding of this phenomena we study an analogous problem in the evolution of equatorial geodesics about a central Kerr black hole. A similar threshold of capture exists for appropriate classes of initial conditions, and tuning to threshold the geodesics approach one of the unstable circular geodesics of the Kerr spacetime. Remarkably, with a natural mapping of the parameters of the geodesic to that of the equal mass system, the scaling exponent describing the whirl phase of each system turns out to be quite similar. Armed with this lone piece of evidence that an approximate correspondence might exist between near-threshold evolution of geodesics and generic binary mergers, we illustrate how this information can be used to estimate the cross section and energy emitted in the ultra relativistic black hole scattering problem. This could eventually be of use in providing estimates for the related problem of parton collisions at the Large Hadron Collider in extra dimension scenarios where black holes are produced.Comment: 16 pages, 12 figures; updated to coincide with journal versio

Gravity-dominated unequal-mass black hole collisions

We continue our series of studies of high-energy collisions of black holes investigating unequal-mass, boosted head-on collisions in four dimensions. We show that the fraction of the center-of-mass energy radiated as gravitational waves becomes independent of mass ratio and approximately equal to $13\%$ at large energies. We support this conclusion with calculations using black hole perturbation theory and Smarr's zero-frequency limit approximation. These results lend strong support to the conjecture that the detailed structure of the colliding objects is irrelevant at high energies.This work was supported by the H2020-MSCA-RISE-2015 Grant No. StronGrHEP- 690904, the SDSC Comet and TACC Stampede clusters through NSF-XSEDE Grant No. PHY-090003, STFC Consolidator Grant No. ST/L000636/1, and DiRAC’s Cosmos Shared Memory system through BIS Grant No. ST/J005673/1 and STFC Grant Nos. ST/H008586/1, ST/K00333X/1. E.B. is supported by NSF CAREER Grant No. PHY-1055103 and by FCT contract IF/00797/2014/CP1214/CT0012 under the IF2014 Programme. V.C. thanks the Departament de F´ısica Fonamental at Universitat de Barcelona for hospitality while this work was being completed. V.C. and U.S. acknowledge financial support provided under the European Union’s H2020 ERC Consolidator Grant “Matter and strong-field gravity: New frontiers in Einstein’s theory” grant agreement no. MaGRaTh–646597. V.C. also acknowledges financial support from FCT under Sabbatical Fellowship nr. SFRH/BSAB/105955/2014. F.P. acknowledges financial support from the Simons Foundation and NSF grant PHY-1305682. This research was supported in part by the Perimeter Institute for Theoretical Physics. Research at Perimeter Institute is supported by the Government of Canada through Industry Canada and by the Province of Ontario through the Ministry of Economic Development & Innovation.This is the author accepted manuscript. The final version is available from APS Physics via http://dx.doi.org/10.1103/PhysRevD.93.04401

Volatile components of the anal gland secretion of the striped polecat Ictonyx striatus

The volatile components of the anal gland secretion of an adult, male, Ictonyx striatus were separated and identified by dynamic solvent effect sampling, capillary gas-liquid chromatography, and mass spectrometry. The major component was 2-ethylthiacyclobutane. Nine other sulphur compounds, a ketone, and a hydrocarbon were also identified. Some of these occur in the anal gland secretions of other mustelids

Developing and improving quality efficiency in the South Africa energy industry

Businesses today need to be more effective and efficient in order to design the best products and provide outstanding services to their customers. The purpose of this research is to develop and improve quality efficiency while sustaining continuous improvement at a South African Energy provider's Mpumalanga plant, which is one of the nine regions in South Africa. Accomplishing quality efficiency is challenging, as customers expect quality of service at all times. In general an organisation's or a business's success depends on the reliability of delivering electricity. Therefore the South African Energy provider should be able and capable to deliver electricity at all times. Current research results revealed that: (1) organisations need to do more to raise quality awareness and inform other employees about the quality unit, (2) organisations should go the extra mile in planning, monitoring and evaluating quality, (3) departmental quality objectives and goals should involve employees in formulating the goals and objectives, eliminating misunderstanding and mistakes committed by the workforce where quality is concerned, (4) management should be committed and involved in accomplishing quality efficiency in any capacity and making sure that continuous improvement is sustained, (5) commitment by management and employee recognition will improve capability, performance and innovation. The research study accordingly has a realistic and methodological significance in terms of achieving and improving quality efficiency and sustaining continuous improvement in providing energy in South Africa

Learning about compact binary merger: the interplay between numerical relativity and gravitational-wave astronomy

Activities in data analysis and numerical simulation of gravitational waves have to date largely proceeded independently. In this work we study how waveforms obtained from numerical simulations could be effectively used within the data analysis effort to search for gravitational waves from black hole binaries. We propose measures to quantify the accuracy of numerical waveforms for the purpose of data analysis and study how sensitive the analysis is to errors in the waveforms. We estimate that ~100 templates (and ~10 simulations with different mass ratios) are needed to detect waves from non-spinning binary black holes with total masses in the range 100 Msun < M < 400 Msun using initial LIGO. Of course, many more simulation runs will be needed to confirm that the correct physics is captured in the numerical evolutions. From this perspective, we also discuss sources of systematic errors in numerical waveform extraction and provide order of magnitude estimates for the computational cost of simulations that could be used to estimate the cost of parameter space surveys. Finally, we discuss what information from near-future numerical simulations of compact binary systems would be most useful for enhancing the detectability of such events with contemporary gravitational wave detectors and emphasize the role of numerical simulations for the interpretation of eventual gravitational-wave observations.Comment: 19 pages, 12 figure

High ferritin levels have major effects on the morphology of erythrocytes in Alzheimer's disease

Introduction: Unliganded iron both contributes to the pathology of Alzheimer's disease (AD) and also changes the morphology of erythrocytes (RBCs). We tested the hypothesis that these two facts might be linked, i.e., that the RBCs of AD individuals have a variant morphology, that might have diagnostic or prognostic value. Methods: We included a literature survey of AD and its relationships to the vascular system, followed by a laboratory study. Four different microscopy techniques were used and results statistically compared to analyze trends between high and normal serum ferritin (SF) AD individuals. Results: Light and scanning electron microscopies showed little difference between the morphologies of RBCs taken from healthy individuals and from normal SF AD individuals. By contrast, there were substantial changes in the morphology of RBCs taken from high SF AD individuals. These differences were also observed using confocal microscopy and as a significantly greater membrane stiffness (measured using force-distance curves). Conclusion: We argue that high ferritin levels may contribute to an accelerated pathology in AD. Our findings reinforce the importance of (unliganded) iron in AD, and suggest the possibility both of an early diagnosis and some means of treating or slowing down the progress of this disease

Resource allocation in applications research : challenges and strategies of small technology developing companies

Thesis (S.M.)--Massachusetts Institute of Technology, System Design & Management Program, February 2004.Includes bibliographical references (p. 69-72).This is a study into the allocation of resources in the early stages of research in a small commercial entity that develops innovative technologies. The premise is that resource allocation must focus on the implementation of the technology from a broad, end-to-end, systems viewpoint rather than purely on the inventive or scientific research. Only by understanding and addressing issues early in a development process can technology be efficiently developed. This thesis examines in depth the approach to the development of technologies taken by eight small innovative research companies in the New England Area. These companies all received funding through the government's Small Business Innovative Research program. Half of the companies received additional funding from external entities and qualified for Fast Track funding from the Department of Defense. The study was conducted by means of a questionnaire and in person interviews to identify how companies identify, evaluate and allocate resources to challenges. The strategies that were followed, problems encountered, collaborations with other entities and the outcomes of their programs were examined. This process set up a natural experiment between companies that received Fast Track and thus external funding on the basis of augmented external communication. The main conclusions of the research are that the Fast Track program, for the small sample studied here, did not influence the processes followed by the companies. Rather the long-term strategies of the companies dictated how they dealt with adversity. Moreover, in contradiction to previous studies that examined these same companies immediately after the SBIR work was completed, the fast-track companies showed no greater commercialization(cont.) success than the comparison companies. The diminished differentiator of the Fast Track program can be attributed to a) the great deal of uncertainty that is inherent with applications research and b) the short time and limited funding of the SBIR program, which in itself limits the probability of success independent of the Fast-Track mechanism.by Jacob v.R. Pretorius.S.M