52 research outputs found

    Massive Star Formation

    Full text link
    This chapter reviews progress in the field of massive star formation. It focuses on evidence for accretion and current models that invoke high accretion rates. In particular it is noted that high accretion rates will cause the massive young stellar object to have a radius much larger than its eventual main sequence radius throughout much of the accretion phase. This results in low effective temperatures which may provide the explanation as to why luminous young stellar objects do not ionized their surroundings to form ultra-compact H II regions. The transition to the ultra-compact H II region phase would then be associated with the termination of the high accretion rate phase. Objects thought to be in a transition phase are discussed and diagnostic diagrams to distinguish between massive young stellar objects and ultra-compact H II regions in terms of line widths and radio luminosity are presented.Comment: 21 pages, 6 figures, chapter in Diffuse Matter from Star Forming Regions to Active Galaxies - A Volume Honouring John Dyson, Edited by T.W. Hartquist, J. M. Pittard, and S. A. E. G. Falle. Series: Astrophysics and Space Science Proceedings. Springer Dordrecht, 2007, p.6

    Injury potential in modern ice hockey

    No full text

    Acoustic Kinematics of Helicopter BVI Noise

    No full text

    Reconstruction of multiple myeloma lesions around the pelvis and acetabulum

    No full text
    Multiple myeloma is a malignancy of monoclonal plasma cells (plasma cells are of B-lymphocyte lineage of the hematopoietic system). It is the second most prevalent blood malignancy after non-Hodgkin’s lymphoma. It accounts for approximately 1 % of all malignancies and 2 % of all cancer deaths. Bony involvement is very common; the incidence of pelvic and periacetabular involvement in MM is reported to be around 6 %. Lytic lesions comprise a hallmark of multiple myeloma, which may be complicated with pathologic fractures in a substantial percentage of patients. Pelvic and periacetabular bony involvement of multiple myeloma is associated with some unique characteristics regarding the biomechanics of this specific anatomical region, the morbidity, the overall survival, and prognosis, which all reflect to impairment of quality of life. In this paper, we review the special features of multiple myeloma lesions around the pelvis and acetabulum and present an algorithm of management with the use of current surgical techniques. © 2014, Springer-Verlag France

    Aneurysmal bone cyst of the spine: Management and outcome

    No full text
    Study Design. The clinical records, radiographs, histologic sections, and operative reports of 52 consecutive patients with an aneurysmal bone cyst of the spine were reviewed to evaluate diagnostic and therapeutic options and to correlate treatment and outcome. Objectives. To define the incidence, clinical presentation, diagnostic and therapeutic options, and prognosis of patients with aneurysmal bone cyst of the spine. Summary of Background Data. There are special considerations in the management of spinal lesions: relative inaccessibility of the lesions, associated intraoperative bleeding, necessary of removing the entire lesion to avoid the possibility of recurrence proximity of the lesion to the spinal cord and nerve roots, and potential postoperative bony spinal instability. Methods. Fifty-two consecutive patients with an aneurysmal bone cyst of the spine were treated from 1910 to 1993. Forty patients initially treated for a primary lesion had operative treatment (19 intralesional excision and bone grafting and 21 intralesional excision), four also had adjuvant radiation therapy. Preoperative arterial embolization was performed in two. Results. There was a recurrence rate of 10% within 10 years. All recurrences were noted less than 6 months after surgery. Of 12 patients treated for a recurrent lesion two had a subsequent recurrence (16.7%) within 9 years. At last follow up examination, 50 patients (96%) were free of the disease. One patient died of postradiation osteosarcoma, and one died of intraoperative bleeding. Conclusion. Current treatment recommendations involved preoperative selective arterial embolization, intralesional excision curettage, bone grafting, and fusion of the affected area if instability is present
    corecore