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Primary Mass (primary + mass)

Distribution by Scientific Domains

Medical Sciences	50%

Selected Abstracts

Benign ectopic thyroid tissue in a cutaneous location: a case report and review

JOURNAL OF CUTANEOUS PATHOLOGY, Issue 2 2004
Kim Maino
Background:, For many years, lateral, aberrant thyroid tissue in adults was a term used almost exclusively for metastatic thyroid carcinoma. However, aberrant, benign ectopic thyroid tissue does occur, and it is most commonly found as a part of the evaluation of endocrine dysfunction. Rarely, aberrant, benign ectopic thyroid presents as a primary mass. Case report:, We present a 35-year-old female who presented for removal of a lifelong posterior lateral neck nodule. Results:, Histologic examination and immunohistochemical studies confirmed the presence of aberrant, benign ectopic thyroid tissue. The patient had no endocrine problems, and she had a normally located and functioning thyroid gland. Conclusions:, This case illustrates that not all aberrant thyroid tissues in adults are malignant or associated with endocrine disorders. This case also illustrates the rare association of ectopic thyroid and a normally located and functioning thyroid gland. In this patient, a somatic mutation in a transcription factor important in thyroid migration could explain these findings. [source]

Optical photometry and spectroscopy of the accretion-powered millisecond pulsar HETE J1900.1 , 2455

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 4 2008
P. Elebert
ABSTRACT We present phase resolved optical photometry and spectroscopy of the accreting millisecond pulsar HETE J1900.1,2455. Our R -band light curves exhibit a sinusoidal modulation, at close to the orbital period, which we initially attributed to X-ray heating of the irradiated face of the secondary star. However, further analysis reveals that the source of the modulation is more likely due to superhumps caused by a precessing accretion disc. Doppler tomography of a broad H, emission line reveals an emission ring, consistent with that expected from an accretion disc. Using the velocity of the emission ring as an estimate for the projected outer disc velocity, we constrain the maximum projected velocity of the secondary to be 200 km s,1, placing a lower limit of 0.05 M, on the secondary mass. For a 1.4 M, primary, this implies that the orbital inclination is low, ,20°. Utilizing the observed relationship between the secondary mass and the orbital period in short-period cataclysmic variables, we estimate the secondary mass to be ,0.085 M,, which implies an upper limit of ,2.4 M, for the primary mass. [source]

On the properties of young multiple stars

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 2 2004
E. J. Delgado-Donate
ABSTRACT We present numerical results on the properties of young binary and multiple stellar systems. Our analysis is based on a series of smoothed particle hydrodynamics (SPH) +N -body simulations of the fragmentation of small molecular clouds, which fully resolve the opacity limit for fragmentation. These simulations demonstrate that multiple star formation is a major channel for star formation in turbulent flows. We have produced a statistically significant number of stable multiple systems, with component separations in the range ,1,103 au. At the end of the hydrodynamic stage (0.5 Myr), we find that ,60 per cent of stars and brown dwarfs are members of multiples systems, with about a third of these being low-mass, weakly bound outliers in wide eccentric orbits. Our results imply that in the stellar regime most stars are in multiples (,80 per cent) and that this fraction is an increasing function of primary mass. After N -body integration to 10.5 Myr, the percentage of bound objects has dropped to about 40 per cent, this decrease arising mostly from very low-mass stars and brown dwarfs that have been released into the field. Brown dwarfs are never found to be very close companions to stars (the brown dwarf desert at very small separations), but one case exists of a brown dwarf companion at intermediate separations (10 au). Our simulations can accommodate the existence of brown dwarf companions at large separations, but only if the primaries of these systems are themselves multiples. We have compared the outcome of our simulations with the properties of real stellar systems as deduced from the infrared colour,magnitude diagram of the Praesepe cluster and from spectroscopic and high-resolution imaging surveys of young clusters and the field. We find that the spread of the observed main sequence of Praesepe in the 0.4,1 M, range appears to require that stars are indeed commonly assembled into high-order multiple systems. Similarly, observational results from Taurus and , Ophiuchus, or moving groups such as TW Hydrae and MBM 12, suggest that companion frequencies in young systems can indeed be as high as we predict. The comparison with observational data also illustrates two problems with the simulation results. First, low mass ratio (q < 0.2) binaries are not produced by our models, in conflict with both the Praesepe colour,magnitude diagram and independent evidence from field binary surveys. Secondly, very low-mass stars and brown dwarf binaries appear to be considerably underproduced by our simulations. [source]

Extraosseous osteosarcoma: Single institutional experience in Korea

ASIA-PACIFIC JOURNAL OF CLINICAL ONCOLOGY, Issue 2 2010
Soohyeon LEE
Abstract Aim: Extraosseous osteosarcoma (EOO) is a rare soft tissue form of osteosarcoma without involvement of the skeletal system. Due to the rarity of disease, its clinical features and optimal treatment are yet to be defined. Methods: Between 1 January 1999 and 30 June 2008 ten patients were pathologically confirmed with extra-skeletal osteosarcoma. A retrospective analysis of the ten patients was performed. Results: The anatomical distribution of the osteosarcomas was as follows: lower extremities (n = 3), upper extremities (n = 2), breast (n = 2), lung (n = 1), cheek (n = 1) and retroperitoneum (n = 1). Nine patients initially underwent resection of the primary mass. One patient, who received six cycles of adjuvant doxorubicin and cisplatin chemotherapy was alive in remission at 42.6 months. One patient with postoperative radiotherapy after curative surgery was alive in remission at 6.2 months. However, all three patients who received curative resection but no postoperative radiotherapy or chemotherapy died of the disease at 10.7, 11.1 and 15.6 months after surgery. The median time to failure was only 4.4 months (95% CI, 0.6, 8.2 months) and the median survival time of all patients was only 11.1 months (95% CI, 5.6, 16.6 months). At the time of analysis, seven patients were dead and all died of the disease recurrence. Conclusion: EOO should be treated as a soft tissue sarcoma with aggressive behavior and multimodality treatment should be actively sought to improve treatment outcome. The impact of adjuvant chemotherapy on survival of EOO needs further investigation. [source]