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Your search keyword '"Kwon, H. J."' showing total 14 results
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14 results on '"Kwon, H. J."'

1. Three-year annual modulation search with COSINE-100

Author

Collaboration, COSINE-100, Adhikari, G., de Souza, E. Barbosa, Carlin, N., Choi, J. J., Choi, S., Ezeribe, A. C., França, L. E., Ha, C., Hahn, I. S., Hollick, S. J., Jeon, E. J., Jo, J. H., Joo, H. W., Kang, W. G., Kauer, M., Kim, H., Kim, H. J., Kim, J., Kim, K. W., Kim, S. H., Kim, S. K., Kim, W. K., Kim, Y. D., Kim, Y. H., Ko, Y. J., Kwon, H. J., Lee, D. H., Lee, E. K., Lee, H., Lee, H. S., Lee, H. Y., Lee, I. S., Lee, J., Lee, J. Y., Lee, M. H., Lee, S. H., Lee, S. M., Leonard, D. S., Manzato, B. B., Maruyama, R. H., Neal, R. J., Olsen, S. L., Park, B. J., Park, H. K., Park, H. S., Park, K. S., Park, S. D., Pitta, R. L. C., Prihtiadi, H., Ra, S. J., Rott, C., Shin, K. A., Scarff, A., Spooner, N. J. C., Thompson, W. G., Yang, L., and Yu, G. H.

Subjects
High Energy Physics - Experiment, Astrophysics - Instrumentation and Methods for Astrophysics, Physics - Instrumentation and Detectors
Abstract

COSINE-100 is a direct detection dark matter experiment that aims to test DAMA/LIBRA's claim of dark matter discovery by searching for a dark matter-induced annual modulation signal with NaI(Tl) detectors. We present new constraints on the annual modulation signal from a dataset with a 2.82 yr livetime utilizing an active mass of 61.3 kg, for a total exposure of 173 kg$\cdot$yr. This new result features an improved event selection that allows for both lowering the energy threshold to 1 keV and a more precise time-dependent background model. In the 1-6 keV and 2-6 keV energy intervals, we observe best-fit values for the modulation amplitude of 0.0067$\pm$0.0042 and 0.0051$\pm$0.0047 counts/(day$\cdot$kg$\cdot$keV), respectively, with a phase fixed at 152.5 days., Comment: 11 pages, 8 figures

Published
2021
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2. Searching for low-mass dark matter via Migdal effect in COSINE-100

Author

Adhikari, G., Carlin, N., Choi, J. J., Choi, S., Ezeribe, A. C., Franca, L. E., Ha, C., Hahn, I. S., Hollick, S. J., Jeon, E. J., Jo, J. H., Joo, H. W., Kang, W. G., Kauer, M., Kim, H., Kim, H. J., Kim, J., Kim, K. W., Kim, S. H., Kim, S. K., Kim, W. K., Kim, Y. D., Kim, Y. H., Ko, Y. J., Kwon, H. J., Lee, D. H., Lee, E. K., Lee, H., Lee, H. S., Lee, H. Y., Lee, I. S., Lee, J., Lee, J. Y., Lee, M. H., Lee, S. H., Lee, S. M., Leonard, D. S., Manzato, B. B., Maruyama, R. H., Neal, R. J., Olsen, S. L., Park, B. J., Park, H. K., Park, H. S., Park, K. S., Park, S. D., Pitta, R. L. C., Prihtiadi, H., Ra, S. J., Rott, C., Shin, K. A., Scarff, A., Spooner, N. J. C., Thompson, W. G., Yang, L., and Yu, G. H.

Subjects
High Energy Physics - Experiment, Astrophysics - Instrumentation and Methods for Astrophysics
Abstract

We report on the search for weakly interacting massive particle (WIMP) dark matter candidates in the galactic halo that interact with sodium and iodine nuclei in the COSINE-100 experiment and produce energetic electrons that accompany recoil nuclei via the the Migdal effect. The WIMP mass sensitivity of previous COSINE-100 searches that relied on the detection of ionization signals produced by target nuclei recoiling from elastic WIMP-nucleus scattering was restricted to WIMP masses above $\sim$5 GeV/$c^2$ by the detectors' 1 keVee energy-electron-equivalent threshold. The search reported here looks for recoil signals enhanced by the Migdal electrons that are ejected during the scattering process. This is particularly effective for the detection of low-mass WIMP scattering from the crystals' sodium nuclei in which a relatively larger fraction of the WIMP's energy is transferred to the nucleus recoil energy and the excitation of its orbital electrons. In this analysis, the low-mass WIMP search window of the COSINE-100 experiment is extended to WIMP mass down to 200 MeV/$c^2$. The low-mass WIMP sensitivity will be further improved by lowering the analysis threshold based on a multivariable analysis technique. We consider the influence of these improvements and recent developments in detector performance to re-evaluate sensitivities for the future COSINE-200 experiment. With a 0.2 keVee analysis threshold and high light-yield NaI(Tl) detectors (22 photoelectrons/keVee), the COSINE-200 experiment can explore low-mass WIMPs down to 20 MeV/$c^2$ and probe previously unexplored regions of parameter space., Comment: 10 pages, 8 figures

Published
2021
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7. Critical Current Densities and n-Values of MgB2 Conductors for SMES, MRI, and Low AC Loss Applications

Author

Kwon, H. J., Rochester, J., Wan, F., Rindfleisch, M. A., Tomsic, M. J., Sumption, M. D., and Collings, E. W.

Abstract

Multifilamentary MgB2 strands (filament numbers 36 to 114) prepared by the in-situ power-in-tube (PIT) route with carbon doping contents of 0, 2, and 3.2% were wound on barrels for transport Jc and n-value measurement at 4.2 K in fields of up to 12 T. The strand and gauge lengths were 1 m and 0.5 m. Heat treatments at 675 °C and 650 °C centered around the melting point of Mg (650 °C) and both utilized the liquid-solid reaction. A pair of strands, with and without 2% C doping exhibited the Jc (B) crossover effect. Studied were the dependencies of Jc on field strength, dopant concentration, and cabling and the dependence of n-value on field strength.

Published
2023
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10. Three-year annual modulation search with COSINE-100

Author

100 Collaboration, Adhikari, G., de Souza, E. Barbosa, Carlin, N., Choi, J. J., Choi, S., Ezeribe, A. C., França, L. E., Ha, C., Hahn, I. S., Hollick, S. J., Jeon, E. J., Jo, J. H., Joo, H. W., Kang, W. G., Kauer, M., Kim, H., Kim, H. J., Kim, J., Kim, K. W., Kim, S. H., Kim, S. K., Kim, W. K., Kim, Y. D., Kim, Y. H., Ko, Y. J., Kwon, H. J., Lee, D. H., Lee, E. K., Lee, H., Lee, H. S., Lee, H. Y., Lee, I. S., Lee, J., Lee, J. Y., Lee, M. H., Lee, S. H., Lee, S. M., Leonard, D. S., Manzato, B. B., Maruyama, R. H., Neal, R. J., Olsen, S. L., Park, B. J., Park, H. K., Park, H. S., Park, K. S., Park, S. D., Pitta, R. L. C., Prihtiadi, H., Ra, S. J., Rott, C., Shin, K. A., Scarff, A., Spooner, N. J. C., Thompson, W. G., Yang, L., and Yu, G. H.

Subjects
High Energy Physics - Experiment (hep-ex), Physics - Instrumentation and Detectors, FOS: Physical sciences, Instrumentation and Detectors (physics.ins-det), Astrophysics - Instrumentation and Methods for Astrophysics, Instrumentation and Methods for Astrophysics (astro-ph.IM), High Energy Physics - Experiment
Abstract

COSINE-100 is a direct detection dark matter experiment that aims to test DAMA/LIBRA's claim of dark matter discovery by searching for a dark matter-induced annual modulation signal with NaI(Tl) detectors. We present new constraints on the annual modulation signal from a dataset with a 2.82 yr livetime utilizing an active mass of 61.3 kg, for a total exposure of 173 kg$\cdot$yr. This new result features an improved event selection that allows for both lowering the energy threshold to 1 keV and a more precise time-dependent background model. In the 1-6 keV and 2-6 keV energy intervals, we observe best-fit values for the modulation amplitude of 0.0067$\pm$0.0042 and 0.0051$\pm$0.0047 counts/(day$\cdot$kg$\cdot$keV), respectively, with a phase fixed at 152.5 days., 11 pages, 8 figures

Published
2021

13. MSX1 Drives Tooth Morphogenesis Through Controlling Wnt Signaling Activity.

Author

Lee JM, Qin C, Chai OH, Lan Y, Jiang R, and Kwon HE

Subjects
Animals, Bone Morphogenetic Protein 4, Gene Expression Regulation, Developmental, MSX1 Transcription Factor genetics, Mesoderm, Mice, Morphogenesis, Odontogenesis genetics, Tooth Germ metabolism, Tooth metabolism, Wnt Signaling Pathway
Abstract

Tooth agenesis is a common structural birth defect in humans that results from failure of morphogenesis during early tooth development. The homeobox transcription factor Msx1 and the canonical Wnt signaling pathway are essential for "bud to cap" morphogenesis and are causal factors for tooth agenesis. Our recent study suggested that Msx1 regulates Wnt signaling during early tooth development by suppressing the expression of Dkk2 and Sfrp2 in the tooth bud mesenchyme, and it demonstrated partial rescue of Msx1 -deficient molar teeth by a combination of DKK inhibition and genetic inactivation of SFRPs. In this study, we found that Sostdc1/Wise, another secreted Wnt antagonist, is involved in regulating the odontogenic pathway downstream of Msx1. Whereas Sostdc1 expression in the developing tooth germ was not increased in Msx1 -/- embryos, genetic inactivation of Sostdc1 rescued maxillary molar, but not mandibular molar, morphogenesis in Msx1 -/- mice with full penetrance. Since the Msx1 -/- ; Sostdc1 -/- embryos exhibited ectopic Dkk2 expression in the developing dental mesenchyme, similar to Msx1 -/- embryos, we generated and analyzed tooth development in Msx1 -/- ; Dkk2 -/- double and Msx1 -/- ; Dkk2 -/- ; Sostdc1 -/- triple mutant mice. The Msx1 -/- ; Dkk2 -/- double mutants showed rescued maxillary molar morphogenesis at high penetrance, with a small percentage also exhibiting mandibular molars that transitioned to the cap stage. Furthermore, tooth development was rescued in the maxillary and mandibular molars, with full penetrance, in the Msx1 -/- ; Dkk2 -/- ; Sostdc1 -/- mice. Together, these data reveal 1) that a key role of Msx1 in driving tooth development through the bud-to-cap transition is to control the expression of Dkk2 and 2) that modulation of Wnt signaling activity by Dkk2 and Sostdc1 plays a crucial role in the Msx1-dependent odontogenic pathway during early tooth morphogenesis.

Published
2022
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14. Brain metastases: An update on the multi-disciplinary approach of clinical management.

Author

Mitchell DK, Kwon HJ, Kubica PA, Huff WX, O'Regan R, and Dey M

Subjects
Adult, Aged, Cranial Irradiation, Humans, Prognosis, Quality of Life, Retrospective Studies, Salvage Therapy, Brain Neoplasms surgery, Radiosurgery
Abstract

Importance: Brain metastasis (BM) is the most common malignant intracranial neoplasm in adults with over 100,000 new cases annually in the United States and outnumbering primary brain tumors 10:1., Observations: The incidence of BM in adult cancer patients ranges from 10-40%, and is increasing with improved surveillance, effective systemic therapy, and an aging population. The overall prognosis of cancer patients is largely dependent on the presence or absence of brain metastasis, and therefore, a timely and accurate diagnosis is crucial for improving long-term outcomes, especially in the current era of significantly improved systemic therapy for many common cancers. BM should be suspected in any cancer patient who develops new neurological deficits or behavioral abnormalities. Gadolinium enhanced MRI is the preferred imaging technique and BM must be distinguished from other pathologies. Large, symptomatic lesion(s) in patients with good functional status are best treated with surgery and stereotactic radiosurgery (SRS). Due to neurocognitive side effects and improved overall survival of cancer patients, whole brain radiotherapy (WBRT) is reserved as salvage therapy for patients with multiple lesions or as palliation. Newer approaches including multi-lesion stereotactic surgery, targeted therapy, and immunotherapy are also being investigated to improve outcomes while preserving quality of life., Conclusion: With the significant advancements in the systemic treatment for cancer patients, addressing BM effectively is critical for overall survival. In addition to patient's performance status, therapeutic approach should be based on the type of primary tumor and associated molecular profile as well as the size, number, and location of metastatic lesion(s)., (Copyright © 2021 Elsevier Masson SAS. All rights reserved.)

Published
2022
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