• Journal of The Korean Astronomical Society
• /
• v.29 no.spc1
• /
• pp.119-122
• /
• 1996

The case for a massive black hole in the center of the Galaxy is reassessed using improved modeling techniques and observational data. A dark mass of ${\~}{\times} 10^6$ Mo is present within 0.2 pc of the Galactic center. However, the available data can be modeled, without appealing to a massive black hole, using an extended distribution of dark stellar remnants (neutron stars and stellar mass black holes) provided that the stellar initial mass function in the central parsec is deficient in stars less massive than $\~$1 Mo. Such a situation may be a natural consequence of repeated gas build-up followed by starbursts in the central region. A clear distinction between this and the massive central black hole model cannot be made using red giant tracers outside 0.2 pc due to uncertainties in the radial velocity dispersion distribution. The cluster of massive early-type emission-line stars in the central parcsec more effectively probe the mass distribution close to Sgr A $\ast$, but their small number and partial rotational support complicate mass determinations. Proper motion determinations for stars within 0.5' of Sgr A$\ast$ may be the most effective means of unambiguously determining the mass distribution in the immediate vicinity of the Galactic center.

• Mass Spectrometry Letters
• /
• v.9 no.4
• /
• pp.105-109
• /
• 2018

A certified reference material (CRM) for the analysis of inorganic nutrients in nutritional supplements has been developed. Accurate mass fractions of chromium (Cr), iron (Fe), copper (Cu), and zinc (Zn) were determined by isotope dilution inductively coupled plasma mass spectrometry (ID ICP/MS). The measurement results were used to assign certified values for the CRM, which were metrologically traceable to the definitions of the measurement units in the International System of Units (SI). Production of a candidate reference material (RM) and the certification processes are summarized. Each nutrient in the CRM showed good homogeneity, which was estimated using relative standard deviations of the measurement results of twelve bottles in a batch. This CRM is expected to be an important reference to improve reliability and comparability of nutrient analyses in nutritional supplements and related samples in analytical laboratories.

• Current Optics and Photonics
• /
• v.2 no.6
• /
• pp.589-594
• /
• 2018

We have investigated the dimensional nature of center-of-mass exciton confinement states in a CdMnTe/CdTe/CdMnTe heterostructure, where the CdTe well is too wide (144 nm) to confine both electrons and holes but able to confine whole excitons in the center-of-mass coordinate. Fine multiple photoluminescence spectra with a few meV separation were observed at 6 K. From the thickness dependence of the transition rate, they were attributed to even numbered center-of-mass exciton confinement states (N = 2, 4, 6, ${\cdots}$, 18). Dimensionality of the center-of-mass exciton confinement states was also investigated in terms of temperature dependence of radiative decay time. At low temperatures (${\leq}12K$), we found that the ground state excitons are likely localized possibly due to the barrier interface fluctuation, resulting in a constant decay time (~350 ps). With increased temperature (${\geq}12K$), localized excitons are thermally released, giving rise to a linear temperature dependence of radiative decay time as an evidence of two-dimensional nature.

• Investigative Magnetic Resonance Imaging
• /
• v.19 no.3
• /
• pp.191-195
• /
• 2015

We present a 53-year-old woman with a large chest wall mass in the interpectoral space, which was eventually confirmed as a lipogranuloma resulting from hydrogel implant rupture. Ultrasonography (US) showed reduced implant volume with surrounding peri-implant fluid collection, suggesting the possibility of implant rupture. A heterogeneously hypoechoic mass was found between the pectoralis major and minor muscles adjacent to the ruptured implant. On magnetic resonance imaging (MRI), there was a large mass in the left interpectoral space of the upper inner chest wall. The mass showed slightly high signal intensity (SI) on pre-contrast T1-weighted image (WI) with mixed iso and high SI on T2-WI. The signal of the mass was suppressed using the water suppression technique but not with the fat suppression technique on T2-WI. The mass showed diffuse enhancement upon contrast enhancement. The enhancing kinetics showed persistent enhancement pattern. US-guided core needle biopsy revealed a lipogranuloma and removal confirmed a ruptured PIP hydrogel implant.

• Tuberculosis and Respiratory Diseases
• /
• v.68 no.5
• /
• pp.290-293
• /
• 2010

A hidden primary tumor presenting as an isolated lung mass is a diagnostic challenge to physicians because the diagnosis of lung cancer is likely to be made if the histologic findings are not inconsistent with lung cancer. A large lung mass was found incidentally in a 59-year-old man. Although adenocarcinoma was diagnosed by percutaneous needle biopsy, thyroid transcription factor-1 (TTF-1) immunostaining was negative, raising suspicion that there was another primary site. There was no abnormal finding except for the lung mass on a $^{18}FDG$-PET/CT scan and the patient did not complain of any discomfort. Finally, prostatic cancer was confirmed through the study of tumor markers and prostate-specific antigen (PSA) immunostaining. Because of the rare presentation of a single lung mass in malignancies that have another primary site, physicians should carefully review all data before making a final diagnosis of lung cancer.

• Analytical Science and Technology
• /
• v.24 no.1
• /
• pp.15-23
• /
• 2011

An accurate mass and isotope ratio were determined using a gas chromatography/time of flight mass spectrometer in CI positive mode for the identification of unknown metabolites. High mass tune was used to improve the ion intensity of $[M+H]^+$. Chromatographic resolution and dynamic range enhancement were performed to obtain more reliable accurate masses and correct isotope abundance ratios. Average absolute errors of mass and isotope ratios for 24 reference metabolite -TMS (trimethylsilyl) derivatives were 6.8 ppm, 1.5% of (M+1/M ratio) and 1.7% of (M+2/M ratio), respectively. The correct formulas of twenty one compound were retrieved within top-2 hit from the heuristic algorithm for elemental composition using each accurate mass and isotope abundance ratio.

• Bulletin of the Korean Chemical Society
• /
• v.30 no.8
• /
• pp.1864-1866
• /
• 2009

• Korean Journal of Head & Neck Oncology
• /
• v.14 no.2
• /
• pp.260-262
• /
• 1998

Metastatic squamous carcinoma of the head and neck may rarely present as a cyst in the cervical region. The true incidence of metastatic cystic neck mass is unknown. It is difficult to differentiate metastatic cystic neck mass from congenital cystic neck mass with physical examination and fine needle aspiration biopsy. So the differential diagnosis is dependent on the age of the patient, and therefore in the patient over the 40 years of age, the possibility of a metastatic neck mass should be considered. We report a metastatic cystic neck mass which had been misdiagnosed as a branchial cleft cyst.

• Journal of Veterinary Clinics
• /
• v.40 no.2
• /
• pp.147-151
• /
• 2023

A 6-year-old female Chihuahua was presented to the Animal Medical Center for surgical resection of a perineal mass that had recently increased in size. Ultrasonography revealed a large, homogeneous fatty mass with irregular margins between the surrounding muscle layers due to infiltrating fatty tissues. Cytological findings from fine-needle aspirates revealed numerous sheets and clusters of adipocytes, which was consistent with the fatty mass. Based on ultrasonographic and cytological findings, an infiltrative lipoma was suspected. During the surgery, the perineal mass was found to be non-encapsulated, irregularly marginated, and extensively distributed into the surrounding muscles. The mass extended inside the pelvic cavity and left anal sac. The perineal mass was surgically removed and submitted for histopathologic examination. Histopathology confirmed that the mass was an infiltrative lipoma invading into the anal sac and surrounding muscles. The present report was an unusual presentation of infiltrative lipoma that invaded the anal sac in the perineum.

• Journal of Veterinary Clinics
• /
• v.35 no.5
• /
• pp.233-236
• /
• 2018

A 13-year-old spayed female Beagle dog was referred with high intraocular pressure, hyperemia, and exophthalmos of the left eye and underwent ultrasound, which revealed a mass in the ciliary body of the left eye. Magnetic resonance (MR) imaging was ordered to evaluate invasion of surrounding structures and metastasis to the brain via the optic nerve. On MR imaging, a single, well-defined, smoothly marginated, triangular-to-oval-shaped mass was found. The mass was hyperintense on T1-weighted images and hypointense on T2-weighted images, similar to a previous case of ocular melanoma. The mass originated from the ciliary body and extended from the anterior chamber to the posterior chamber. Slight enhancement was observed in the mass. There was no evidence of invasion into surrounding structures or the optic nerve, and no sign of metastasis to the brain. The mass was histopathologically diagnosed as benign uveal melanocytoma.