99,094 research outputs found
Kerr, M G, VX31428
No full textThis record was harvested from a previous catalogue system and will be withdrawn in 2025. Information in this record may be superseded or incomplete. Visit this record in UMA's new catalogue at: https://archives.library.unimelb.edu.au/nodes/view/397010Surname: KERR. Given Name(s) or Initials: M G. Military Service Number or Last Known Location: VX31428. Missing, Wounded and Prisoner of War Enquiry Card Index Number: 8328.234161
Item: [2016.0049.29303] "Kerr, M G, VX31428
Kerr, L M, QX5719
No full textThis record was harvested from a previous catalogue system and will be withdrawn in 2025. Information in this record may be superseded or incomplete. Visit this record in UMA's new catalogue at: https://archives.library.unimelb.edu.au/nodes/view/397002Surname: KERR. Given Name(s) or Initials: L M. Military Service Number or Last Known Location: QX5719. Missing, Wounded and Prisoner of War Enquiry Card Index Number: 3608.234145
Item: [2016.0049.29295] "Kerr, L M, QX5719
Painlevé–Gullstrand coordinates versus Kerr spacetime geometry
No full textWe discuss the tension between the possible existence of Painlevé–Gullstrand coordinate systems versus the explicit geometrical features of the Kerr spacetime; a subject of interest to Professor Thanu Padmanabhan in the weeks immediately preceding his unexpected death. We shall carefully distinguish strong and weak Painlevé–Gullstrand coordinate systems, and conformal variants thereof, cataloguing what we know can and cannot be done—sometimes we can make explicit global statements, sometimes we must resort to implicit local statements. For the Kerr spacetime the best that seems to be achievable is to set the lapse function to unity and represent the spatial slices with a 3-metric in factorized unimodular form; this arises from considering the Doran version of Kerr spacetime in Cartesian coordinates. We finish by exploring the (limited) extent to which this construction might possibly lead to implementing an “analogue spacetime” model suitable for laboratory simulations of the Kerr spacetime
Superradiance in Kerr-like black holes
No full textRecent strong-field regime tests of gravity are so far in agreement with general relativity. In particular, astrophysical black holes appear all to be consistent with the Kerr spacetime, but the statistical error on current observations allows for small yet detectable deviations from this description. Here we study superradiance of scalar and electromagnetic test fields around the Kerr-like Konoplya-Zhidenko black hole and we observe that for large values of the deformation parameter superradiance is highly suppressed with respect to the Kerr case. Surprisingly, there exists a range of small values of the deformation parameter for which the maximum amplification factor is larger than the Kerr one. We also provide a first result about the superradiant instability of these non-Kerr spacetimes against massive scalar fields
Magneto–Optical Kerr Effect Microscopy Investigation on Permalloy Nanostructures
No full textThis thesis focuses on the investigation of magnetic domains in ultrasmall permalloy (Ni80Fe20) structures down to nanometre size. Magnetic domains and domain walls in nano objects are often observed using a very high resolution and high power microscope such as magnetic soft x-ray microscope, magnetic force microscopy imaging and photoemission electron microscopy. A reason for this is because the Kerr signal in nanostructures is very weak. However the results from this thesis demonstrate that magnetic domains in permalloy magnetic nanostructures can still be observed with very good contrast using a Magneto-optical Kerr effect (MOKE) microscope. The constructed Kerr microscope is a home-build wide field microscope and is able to produce magnetic domains image of permalloy nanowire as small as 245 nm, although the resolution limit of the microscope is 505 nm. For the first time, a magnetic domain in nanowire with width of 245 nm is observed using a wide-field microscope. The combination of hysteresis loops and magnetic domains observations for studying a magnetic sample provides a three-dimensional understanding of the magnetic characteristic of the sample. This is crucial in investigating nano samples as the theoretical arguments with the experimental results are always constrained by the experimental part. Three kinds of nanostructure sample were observed using the Kerr microscope; a cross nanowire, zigzag nanowire and a nanowire with notch and a nucleation pad at one end. It was found that a cross nanowire can form magnetic domains upon reversal and the junction forms a magnetisation vortex. Findings from zigzag nanowire demonstrate a complex, multiple magnetic domains formation upon magnetisation reversal. A weak domain wall pinning effect was observed in the nanowire, causing a multiple domains formation in the nanowire upon reversal. It can be confirmed that this effect was caused by the high coercivity of the nucleation pad. For the nanowire with notch, it was demonstrated that the coercivities were different at negative and positive field. But for such case, there is a relationship observed between the percentage notch depth and the coercivity at the junction
Geologic atlas of the United States : topography, areal geology, economic geology, structure sections / 59 Bristol Folio : Virginia - Tennessee
No full textMarius R. Campbell ; Henry Gannett ; H. M. Wilson ; W. C. Kerr ; S. S. Gannett ; D. C. Harrison ; Gilbert ThompsonList of Sheets: Topography, Historical Geology, Economic Geology, Structure SectionsIndirektes handschriftliches Exlibris: "1901, 594", das ist Geological Survey U. S. Washington Exemplar der ETH-BI
Geologic atlas of the United States : topography, areal geology, economic geology, structure sections / 15/1895 Lassen Peak Folio : California
No full textJ. S. Diller ; Henry Gannett ; Gilbert Thompson ; M. B. Kerr ; J. D. HoffmannList of Sheets: Topography, Areal Geology, Economic Geology, Structure Section
Geodesic Geometry of Black Holes
No full textThe study of geodesics is of intrinsic significance in the study of the geometry of space-time. In this thesis null, space-like and
time-like geodesics are studied in the case of the space-times of Schwarzschild, Reissner-Nordstrouml;m and Kerr black holes. These
space-times have been investigated with varying degrees of thoroughness in many articles and some books. However, there are some significant gaps in these treatments and the central aim of this thesis is to fill these gaps where necessary. Moreover, the following topics are covered for the first time.
1. In Chapter 4 a thorough treatment of the space-like geodesics of the Schwarzschild solutions has been given. These geodesics are the trajectories of Tachyons (faster than light particles) and are
treated in a complete manner. This has been done by obtaining exact solutions and solving them numerically.
2. In Part II all solutions for geodesics for a
Reissner-Nordstrouml;m black hole have been given in complete detail, i.e. time-like, null and space-like geodesics and orbit of a charged particle.
3. In Chapter 14 all solutions for geodesics in the equatorial plane of a Kerr black hole have been given in complete detail, i.e. time-like, null and space-like geodesics.
4. The study of special types of non-equatorial geodesics for a Kerr black hole have been given in complete detail, i.e. time-like (Chapter 17), null (Chapter 15) and space-like (Chapter 16). This has been done in order to distinguish the qualitatively different types of solutions.
Calculation of the explicit formulas, which describe these geodesics, as well as numerically computed diagrams representing the geodesics have been incorporated in these studies. The following subjects have been also treated:
5. Solutions for the geodesics in Reissner-Nordstrouml;m black holes with |Q_*| gt;= M, which are black holes with one (|Q_*| = M) or no horizon (|Q_*|gt; M) (Chapter 8).
6. Solutions of geodesics in extreme and fast Kerr black holes, i.e. black holes with a = M (extreme) and a gt; M (fast). As in the case of |Q_*| gt; M, fast black holes have naked singularities (Chapter 14).
7. Some general observations about orbit types of the Kerr black holes regarding relationships between parameters such as angular momentum, energy, Carter constant and mass and angular momentum of black holes (Chapter 13).
8. Some corrections to errors found in the literature.
While it has not been possible to cover all different cases which occur for possible relations amongst the parameters specifying a
general black hole, interesting geodesics have, however, been studied and a more thorough presentation of the properties of geodesics has now been given
Geologic atlas of the United States : topography, areal geology, economic geology, structure sections / 15 Lassen Peak Sheet : California
No full textJ. S. Diller ; Henry Gannett ; Gilbert Thompson ; M. B. Kerr ; J. D. HoffmannList of Sheets: Topography, Areal Geology, Economic Geology, Structure SectionsExlibrisstempel: "Geolog. Institut von Polytechnikum und Universität in Zürich" 990026379930205503_0001 Exemplar der ETH-BI
SKENARIO PENGHANCURAN LUBANG HITAM KERR
No full textBased on three fundamental papers proposed by Penrose,Wald, and Hawking,
the black hole�s destroying scenario can be made. The main problem of the processes
on destroying a black hole are about the presence of black hole�s angular momentum
and charge. Especially for this research, we only investigate the destroying Kerr
black hole. We show that to destroy a Kerr black hole (especially for destroying near
extreemal Kerr black hole case), one needs to remove its angular momentum. We also
show that the Penrose process is depending on the involved particle�s mass. On the
other hand we also show, an exceeding extreeme condition a > M (which a is a usual
J /M, J is an angular momentum and M is a black hole�s mass), can not be reached
because only the black hole with negative nett-energy can fulfil the condition
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