760 research outputs found
Perturbations of Spacetime around a Stationary Rotating Cosmic String
We consider the metric perturbations around a stationary rotating Nambu-Goto
string in Minkowski spacetime. By solving the linearized Einstein equations, we
study the effects of azimuthal frame-dragging around the rotation axis and
linear frame-dragging along the rotation axis, the Newtonian logarithmic
potential, and the angular deficit around the string as the potential mode. We
also investigate gravitational waves propagating off the string and propagating
along the string, and show that the stationary rotating string emits
gravitational waves toward the directions specified by discrete angles from the
rotation axis. Waveforms, polarizations, and amplitudes which depend on the
direction are shown explicitly.Comment: 30 pages, 6 figures; Minor corrections, references added, published
version in Physical Review
Classification of Cohomogeneity One Strings
We define the cohomogeneity one string, string with continuous symmetries, as
its world surface is tangent to a Killing vector field of a target space. We
classify the Killing vector fields by an equivalence relation using isometries
of the target space. We find that the equivalence classes of Killing vectors in
Minkowski spacetime are partitioned into seven families. It is clarified that
there exist seven types of strings with spacelike symmetries and four types of
strings with timelike symmetries, stationary strings.Comment: 8 page
Strings in five-dimensional anti-de Sitter space with a symmetry
The equation of motion of an extended object in spacetime reduces to an
ordinary differential equation in the presence of symmetry. By properly
defining of the symmetry with notion of cohomogeneity, we discuss the method
for classifying all these extended objects. We carry out the classification for
the strings in the five-dimensional anti-de Sitter space by the effective use
of the local isomorphism between \SO(4,2) and \SU(2,2). We present a
general method for solving the trajectory of the Nambu-Goto string and apply to
a case obtained by the classification, thereby find a new solution which has
properties unique to odd-dimensional anti-de Sitter spaces. The geometry of the
solution is analized and found to be a timelike helicoid-like surface
Non-invasive Localized Heating and Temperature Monitoring based on a Cavity Applicator for Hyperthermia
Non
Results and Problems of Research Works in Indian Subcontinent and China
海外地域調査と地誌学 : 地理学の貢献と課
Occlusal reconstruction of a patient with ameloblastoma ablation using alveolar distraction osteogenesis: a case report
Background Ameloblastoma is one of the most common benign odontogenic neoplasms. Its surgical excision has the potential to lead to postoperative malocclusion. In this case report, we describe the successful interdisciplinary orthodontic treatment of a patient with ameloblastoma who underwent marginal mandibulectomy. Case presentation A woman of 20-year-old was diagnosed with ameloblastoma, and underwent marginal mandibulectomy when she was 8 years of age. She had an excessive overjet (11.5 mm) and a mild open bite (- 1.5 mm) with a severely resorbed atrophic edentulous ridge in the area around the mandibular left lateral incisor, canine and first premolar. An alveolar bone defect associated with tumor resection was regenerated by vertical distraction osteogenesis (DO). Subsequently, 3 dental implants were placed into the reconstructed mandible. Orthodontic treatment using implant-anchored mechanics provided a proper facial profile with significantly improved occlusal function. The occlusion appeared stable for a 7-year retention period. Conclusions These results suggest that surgically assisted and implant anchored-orthodontic approaches might be effective for the correction of such malocclusions
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