• Title/Summary/Keyword: episodic collapse

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Presumptive Border Collie collapse in a dog: serial clinical observation and successful management

  • Ji-Young Lee;Jeong-Min Lee;Jin-Young Kim;Kun-Ho Song;Joong-Hyun Song
    • Korean Journal of Veterinary Research
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    • v.63 no.2
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    • pp.10.1-10.5
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    • 2023
  • A 6-month-old female Border Collie presented with a history of collapse after strenuous exercise. The dog was normal between episodes but experienced loss of focus and ataxia after exercise. This is particularly noticeable under hot weather conditions. No remarkable findings were observed in the diagnostic tests. Based on these results, the patient was tentatively diagnosed with Border Collie collapse (BCC). After exercise restriction, the dog had no episode of collapse and remained clinically well with no signs until the follow-up period of 8 months was complete. To our knowledge, this is the first case report of BCC in South Korea.

Tracing history of the episodic accretion process in protostars

  • Kim, Jaeyeong;Lee, Jeong-Eun;Kim, Chul-Hwan;Hsieh, Tien-Hao;Yang, Yao-Lun;Murillo, Nadia;Aikawa, Yuri;Jeong, Woong-Seob
    • The Bulletin of The Korean Astronomical Society
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    • v.46 no.2
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    • pp.66.3-67
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    • 2021
  • Low-mass stars form by the gravitational collapse of dense molecular cores. Observations and theories of low-mass protostars both suggest that accretion bursts happen in timescales of ~100 years with high accretion rates, so called episodic accretion. One mechanism that triggers accretion bursts is infalling fragments from the outer disk. Such fragmentation happens when the disk is massive enough, preferentially activated during the embedded phase of star formation (Class 0 and I). Most observations and models focus on the gas structure of the protostars undergoing episodic accretion. However, the dust and ice composition are poorly understood, but crucial to the chemical evolution through thermal and energetic processing via accretion burst. During the burst phase, the surrounding material is heated up, and the chemical compositions of gas and ice in the disk and envelope are altered by sublimation of icy molecules from grain surfaces. Such alterations leave imprints in the ice composition even when the temperature returns to the pre-burst level. Thus, chemical compositions of gas and ice retain the history of past bursts. Infrared spectral observations of the Spitzer and AKARI revealed a signature caused by substantial heating, toward many embedded protostars at the quiescent phase. We present the AKARI IRC 2.5-5.0 ㎛ spectra for embedded protostars to trace down the characteristics of accretion burst across the evolutionary stages. The ice compositions obtained from the absorption features therein are used as a clock to measure the timescale after the burst event, comparing the analyses of the gas component that traced the burst frequency using the different refreeze-out timescales. We discuss ice abundances, whose chemical change has been carved in the icy mantle, during the different timescales after the burst ends.

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Sub-mm variability of a YSO (EC53) in Serpens main region : JCMT Transient survey

  • Yoo, Hyunju;Lee, Jeong-Eun;Johnstone, Doug;Mairs, Steve;Herczeg, Gregory
    • The Bulletin of The Korean Astronomical Society
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    • v.42 no.1
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    • pp.39.2-39.2
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    • 2017
  • Stars form through the gravitational collapse of molecular clouds. However, the rate at which a star gains most of its mass and the physics that drives the main phase of stellar growth is still unclear. The typical luminosity of observed protostars is smaller than what expected from the Shu's inside-out collapse model, which predicts a constant mass accretion rate. The episodic accretion model has been suggested as a solution of this luminosity problem. The JCMT Transient survey is a long term monitoring program using JCMT/SCUBA-2 to detect accretion variability of protostars in the eight nearby star-forming regions. Recently, we found a rise of the 850 micron flux at a clump in the Serpens main region at the rate of ~17% relative to the mean flux over previous observations. The submm clump is associated with a class I protostar, EC53, which has been reported as a binary system with a periodic variability. In this talk, we will provide a brief overview of the JCMT Transient Survey project, present the detection of the variable source, and discuss about follow-up observations.

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Inherited Malignant Ventricular Tachyarrhythmia in a German Shepherd (져먼 셰퍼드종 개에서 발생한 유전성 악성 심실성 부정맥증)

  • Lee, Joon-Seok;Lee, Seung-Gon;Park, In-Chul;Hyun, Chang-Baig
    • Journal of Veterinary Clinics
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    • v.23 no.3
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    • pp.329-333
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    • 2006
  • A 9-month-old neutered male German Shepherd dog was referred with the primary complaint of episodic collapse. Apparent abnormal findings were not observed in physical examination, routine biochemistry, and diagnostic imaging studies. In the 12-lead surface ECG after collapse, the dog showed frequent ventricular premature contractions (VPCs) with torsade de pointes. The frequency of VPCs was reduced after lidocaine infusion. Based on the history, findings in event recordings oi the ECG and lidocaine response test, the dog was diagnosed as inherited malignant ventricular tachyarrhythmia. Although the dog was initially responded to oral sotalol therapy, the dog was died suddenly. This report described the first case of malignant ventricular tachyarrhythmia of German Sheperd in Korea.

Flow Analyses of Upper Airway Before and After Maxillomandibular Advancement Surgery for Obstructive Sleep Apnea Patient (폐쇄성 수면무호흡증 환자의 상하악 전진술 후 상기도 내 유동해석)

  • Kim, Hyoung-Ho;Suh, Sang-Ho;Choi, Jin-Young;Kim, Taeyun
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.39 no.5
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    • pp.443-448
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    • 2015
  • Obstructive sleep apnea (OSA) is a syndrome characterized by the repetitive episodic collapse of the upper airway. Maxillomandibular advancement surgery is one of the most effective surgical treatment methods in treating obstructive sleep apnea. The advancement of both maxill and mandible can enlarge the cross-sectional areas and volumes of the postero-superior airway. The purpose of this study is to analyze flow patterns in the upper airway before and after maxillomandibular advancement surgery. Here, we analyzed flow phenomena of inspiration and expiration to prevent obstructive sleep apnea patient from happening side effect. Modeling of the upper airway carried out from clinical CT scanned images. We used time-dependent values for boundary condition. CFD analyses were performed and evaluated section of minimum area (SMA), compared with patient inside upper airway before and after maxillomandibular advancement surgery in SMA, and negative pressure effects. The study showed the greatest enlargment of the section of minimum cross-sectional area. Moreover, the velocity and the negative airway pressure were decreased. According to the result of this study, the maxillomandibular advancement surgery stabilizes the airflow in the postero-superior airway of OSA patients.