Pub Date : 2021-08-29DOI: 10.1109/IRMMW-THz50926.2021.9567033
P. Goldsmith
Millimeter wavelength astronomical spectroscopy started about 50 years ago, with the detection of carbon monoxide in interstellar space. The detection of massive clouds of molecular material in the Milky Way answered a long-standing question of from what stars form, but understanding the formation, structure, and evolution of these clouds demanded ever more sensitive receivers operating throughout the millimeter/submillimeter//THz range. Fractional frequency resolution R>3x105 is required to measure the motions in star-forming regions, with the result that heterodyne systems have become the dominant technology for detailed kinematic studies. To unravel the complexity of chemistry in molecular clouds, higher sensitivity was required. To achieve this, the Schottky diodes initially used as nonlinear elements were first cooled to reduce noise, but then replaced by superconductor insulator superconductor (SIS) and hot electron bolometer (HEB) mixers. Noise temperatures dropped from many thousands of K to < 100 K. Local oscillators (LOs) evolved from vacuum tubes to solid state devices. Large efforts were devoted to the development of frequency multipliers which allow mixers up to several THz to operate, starting with spectrally pure, tunable sources below 100 GHz. These allowed unbiased "spectral scans" and better use of observing time. The quantum cascade laser LO has allowed exploiting frequencies to 5 THz and beyond. Single antennas grew by more than an order of magnitude in collecting area. Interferometric arrays providing unprecedented angular resolution have allowed detailed observations of sources ranging from planet-forming disks to star-forming regions in distant galaxies. The interplay between technology and astronomical spectroscopy has been hugely productive, and continues, with new types of mixers for individual pixels and sophisticated focal plane arrays being developed for ground and space-based applications.
{"title":"How 50 Years of Technology Development Has Transformed Millimeter-THz Astronomical Spectroscopy","authors":"P. Goldsmith","doi":"10.1109/IRMMW-THz50926.2021.9567033","DOIUrl":"https://doi.org/10.1109/IRMMW-THz50926.2021.9567033","url":null,"abstract":"Millimeter wavelength astronomical spectroscopy started about 50 years ago, with the detection of carbon monoxide in interstellar space. The detection of massive clouds of molecular material in the Milky Way answered a long-standing question of from what stars form, but understanding the formation, structure, and evolution of these clouds demanded ever more sensitive receivers operating throughout the millimeter/submillimeter//THz range. Fractional frequency resolution R>3x105 is required to measure the motions in star-forming regions, with the result that heterodyne systems have become the dominant technology for detailed kinematic studies. To unravel the complexity of chemistry in molecular clouds, higher sensitivity was required. To achieve this, the Schottky diodes initially used as nonlinear elements were first cooled to reduce noise, but then replaced by superconductor insulator superconductor (SIS) and hot electron bolometer (HEB) mixers. Noise temperatures dropped from many thousands of K to < 100 K. Local oscillators (LOs) evolved from vacuum tubes to solid state devices. Large efforts were devoted to the development of frequency multipliers which allow mixers up to several THz to operate, starting with spectrally pure, tunable sources below 100 GHz. These allowed unbiased \"spectral scans\" and better use of observing time. The quantum cascade laser LO has allowed exploiting frequencies to 5 THz and beyond. Single antennas grew by more than an order of magnitude in collecting area. Interferometric arrays providing unprecedented angular resolution have allowed detailed observations of sources ranging from planet-forming disks to star-forming regions in distant galaxies. The interplay between technology and astronomical spectroscopy has been hugely productive, and continues, with new types of mixers for individual pixels and sophisticated focal plane arrays being developed for ground and space-based applications.","PeriodicalId":6852,"journal":{"name":"2021 46th International Conference on Infrared, Millimeter and Terahertz Waves (IRMMW-THz)","volume":"77 1","pages":"1-7"},"PeriodicalIF":0.0,"publicationDate":"2021-08-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82661363","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-08-29DOI: 10.1109/IRMMW-THz50926.2021.9566867
Chi-Kan Liu, Lingna Yue, Jia Lu, Ziqing Bai, Wenxiang Wang, Yanyu Wei, Jin Xu, H. Yin, G. Zhao
A W-band U-shaped microstrip meander-line (MML) slow-wave structure (SWS) for traveling-wave tube (TWT) was designed and simulated in this work. The selection of materials used for the dielectric substrate in the SWS was discussed. Meanwhile, to improve the interaction impedance of the SWS, a new structure named conformal dielectric substrate was proposed. According to particle-in-cell (PIC) simulation results, the proposed structure was able to reach an output power of 28.86 W at 96 GHz, with the corresponding maximum gain of 23.8 dB. The 3 dB bandwidth was 7 GHz from 92 GHz to 99 GHz.
{"title":"Study on a W-Band U-shaped Microstrip Meander-line Slow-wave Structure","authors":"Chi-Kan Liu, Lingna Yue, Jia Lu, Ziqing Bai, Wenxiang Wang, Yanyu Wei, Jin Xu, H. Yin, G. Zhao","doi":"10.1109/IRMMW-THz50926.2021.9566867","DOIUrl":"https://doi.org/10.1109/IRMMW-THz50926.2021.9566867","url":null,"abstract":"A W-band U-shaped microstrip meander-line (MML) slow-wave structure (SWS) for traveling-wave tube (TWT) was designed and simulated in this work. The selection of materials used for the dielectric substrate in the SWS was discussed. Meanwhile, to improve the interaction impedance of the SWS, a new structure named conformal dielectric substrate was proposed. According to particle-in-cell (PIC) simulation results, the proposed structure was able to reach an output power of 28.86 W at 96 GHz, with the corresponding maximum gain of 23.8 dB. The 3 dB bandwidth was 7 GHz from 92 GHz to 99 GHz.","PeriodicalId":6852,"journal":{"name":"2021 46th International Conference on Infrared, Millimeter and Terahertz Waves (IRMMW-THz)","volume":"33 1","pages":"1-2"},"PeriodicalIF":0.0,"publicationDate":"2021-08-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82661675","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-08-29DOI: 10.1109/IRMMW-THz50926.2021.9567541
R. Rana, J. Klopf, C. Ciano, Abhishek Singh, S. Winnerl, H. Schneider, M. Helm, A. Pashkin
We demonstrate an optical switch based on gold implanted germanium (Ge:Au) suitable for cavity dumping of a free-electron laser (FEL). We achieve a switching contrast of more than 50 % in a broad range of FEL wavelengths from 6 to 90 µm. A linear relationship between the switching fluence and the frequency of the FEL optical field supported by our simulation highlights the role of a photoinduced finite sub-µm thickness of the reflecting plasma layer. The plasma switch exhibits negligible absorption of the FEL radiation in the ʻoffʼ state and requires only a moderate thermoelectric cooling at incident FEL power of several Watts.
{"title":"Improved Germanium photoswitch for cavity dumping of a free-electron laser","authors":"R. Rana, J. Klopf, C. Ciano, Abhishek Singh, S. Winnerl, H. Schneider, M. Helm, A. Pashkin","doi":"10.1109/IRMMW-THz50926.2021.9567541","DOIUrl":"https://doi.org/10.1109/IRMMW-THz50926.2021.9567541","url":null,"abstract":"We demonstrate an optical switch based on gold implanted germanium (Ge:Au) suitable for cavity dumping of a free-electron laser (FEL). We achieve a switching contrast of more than 50 % in a broad range of FEL wavelengths from 6 to 90 µm. A linear relationship between the switching fluence and the frequency of the FEL optical field supported by our simulation highlights the role of a photoinduced finite sub-µm thickness of the reflecting plasma layer. The plasma switch exhibits negligible absorption of the FEL radiation in the ʻoffʼ state and requires only a moderate thermoelectric cooling at incident FEL power of several Watts.","PeriodicalId":6852,"journal":{"name":"2021 46th International Conference on Infrared, Millimeter and Terahertz Waves (IRMMW-THz)","volume":"16 1","pages":"1-2"},"PeriodicalIF":0.0,"publicationDate":"2021-08-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88992269","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-08-29DOI: 10.1109/IRMMW-THz50926.2021.9567238
M. Lavancier, J. Lampin, R. Peretti
We present a study of liquid water and heavy water in the terahertz range at temperatures between 283K and 348K. We will fit our data with the fit@TDS software that provides a criterion to discriminate good models from others. We will present a comparison between the models proposed in the literature for liquid water and use this criterion to find the most accurate one.
{"title":"Finding the accurate permittivity model for liquid water and heavy water at different temperatures in the Terahertz range","authors":"M. Lavancier, J. Lampin, R. Peretti","doi":"10.1109/IRMMW-THz50926.2021.9567238","DOIUrl":"https://doi.org/10.1109/IRMMW-THz50926.2021.9567238","url":null,"abstract":"We present a study of liquid water and heavy water in the terahertz range at temperatures between 283K and 348K. We will fit our data with the fit@TDS software that provides a criterion to discriminate good models from others. We will present a comparison between the models proposed in the literature for liquid water and use this criterion to find the most accurate one.","PeriodicalId":6852,"journal":{"name":"2021 46th International Conference on Infrared, Millimeter and Terahertz Waves (IRMMW-THz)","volume":"828 ","pages":"1-2"},"PeriodicalIF":0.0,"publicationDate":"2021-08-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91464344","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-08-29DOI: 10.1109/IRMMW-THz50926.2021.9567580
X. Qi, Jingcheng Wang, P. Liang, Zheng Yan, T. Song, Wei Wang, Diwei Liu
A two-dimensional electro-thermal model of bipolar transistor irradiated by high power terahertz wave is established. The transient behaviors of the bipolar transistor are simulated and analyzed when high power terahertz wave is injected. The damage effect of the electric field, current density and temperature are observed theoretically. The voltage amplitude and the frequency on the device are investigated in detail. Empirical formulas of power damage threshold and energy damage threshold with pulse-width are summarized.
{"title":"Damage Effect of Devices Induced by High Power Terahertz-wave","authors":"X. Qi, Jingcheng Wang, P. Liang, Zheng Yan, T. Song, Wei Wang, Diwei Liu","doi":"10.1109/IRMMW-THz50926.2021.9567580","DOIUrl":"https://doi.org/10.1109/IRMMW-THz50926.2021.9567580","url":null,"abstract":"A two-dimensional electro-thermal model of bipolar transistor irradiated by high power terahertz wave is established. The transient behaviors of the bipolar transistor are simulated and analyzed when high power terahertz wave is injected. The damage effect of the electric field, current density and temperature are observed theoretically. The voltage amplitude and the frequency on the device are investigated in detail. Empirical formulas of power damage threshold and energy damage threshold with pulse-width are summarized.","PeriodicalId":6852,"journal":{"name":"2021 46th International Conference on Infrared, Millimeter and Terahertz Waves (IRMMW-THz)","volume":"17 3","pages":"1-2"},"PeriodicalIF":0.0,"publicationDate":"2021-08-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91496767","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-08-29DOI: 10.1109/IRMMW-THz50926.2021.9567524
F. Kuwashima, M. Jarrahi, S. Cakmakyapan, O. Morikawa, T. Shirao, K. Iwao, K. Kurihara, H. Kitahara, T. Furuya, K. Wada, M. Nakajima, M. Tani
Stability of optical beats between longitudinal laser modes in a chaotically oscillated laser diodes for THz wave generation and detection is demonstrated compared to a free-running continuous-wave laser conventional laser. The high stability of chaotically oscillating lasers makes these lasers promising candidates for optical pump sources in terahertz time-domain spectroscopy systems.
{"title":"Stability of optical beats in laser chaos for THz wave generation and detection","authors":"F. Kuwashima, M. Jarrahi, S. Cakmakyapan, O. Morikawa, T. Shirao, K. Iwao, K. Kurihara, H. Kitahara, T. Furuya, K. Wada, M. Nakajima, M. Tani","doi":"10.1109/IRMMW-THz50926.2021.9567524","DOIUrl":"https://doi.org/10.1109/IRMMW-THz50926.2021.9567524","url":null,"abstract":"Stability of optical beats between longitudinal laser modes in a chaotically oscillated laser diodes for THz wave generation and detection is demonstrated compared to a free-running continuous-wave laser conventional laser. The high stability of chaotically oscillating lasers makes these lasers promising candidates for optical pump sources in terahertz time-domain spectroscopy systems.","PeriodicalId":6852,"journal":{"name":"2021 46th International Conference on Infrared, Millimeter and Terahertz Waves (IRMMW-THz)","volume":"19 1","pages":"1-2"},"PeriodicalIF":0.0,"publicationDate":"2021-08-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90239706","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-08-29DOI: 10.1109/IRMMW-THz50926.2021.9567526
A. Rashidi, A. Minasyan, A. Cailly, M. Hamdi, O. Redon, L. Dussopt, H. Yahia
A fast image deconvolution algorithm is used to demonstrate the resolution enhancement of video rate camera acquired Terahertz images. Our algorithm is based on variable splitting technique with the use of a family of sparsity inducing regularizers for the first time in an image deconvolution application, it is also suitable for practical applications in industry with computationally constrained conditions. The results of the proposed process provide substantial enhancement on the quality and resolution of THz images.
{"title":"Fast image deconvolution for enhancement of the resolution in the video rate terahertz imaging","authors":"A. Rashidi, A. Minasyan, A. Cailly, M. Hamdi, O. Redon, L. Dussopt, H. Yahia","doi":"10.1109/IRMMW-THz50926.2021.9567526","DOIUrl":"https://doi.org/10.1109/IRMMW-THz50926.2021.9567526","url":null,"abstract":"A fast image deconvolution algorithm is used to demonstrate the resolution enhancement of video rate camera acquired Terahertz images. Our algorithm is based on variable splitting technique with the use of a family of sparsity inducing regularizers for the first time in an image deconvolution application, it is also suitable for practical applications in industry with computationally constrained conditions. The results of the proposed process provide substantial enhancement on the quality and resolution of THz images.","PeriodicalId":6852,"journal":{"name":"2021 46th International Conference on Infrared, Millimeter and Terahertz Waves (IRMMW-THz)","volume":"27 1","pages":"1-2"},"PeriodicalIF":0.0,"publicationDate":"2021-08-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89146694","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-08-29DOI: 10.1109/IRMMW-THz50926.2021.9567022
H. Du, Jiang Long, Rui-Bo Jin, Tao Wu, Yanjun Fu
Field-free molecular alignment can be induced by the strong ultrashort laser pulses. Here, the improvement of the alignment is completed by the coupled pulses of the ultrashort laser pulse and the strong broadband terahertz pulse. The gaseous CO molecules are aligned by such coupled pulses, and the evolution of its states are studied based on the rigid rotor approximation theory with the simulation method. The influences of the pulses parameters on the alignment are also discussed.
{"title":"Molecular alignment stimulated by the coupled pulses of the ultrashort laser pulse and the terahertz pulse","authors":"H. Du, Jiang Long, Rui-Bo Jin, Tao Wu, Yanjun Fu","doi":"10.1109/IRMMW-THz50926.2021.9567022","DOIUrl":"https://doi.org/10.1109/IRMMW-THz50926.2021.9567022","url":null,"abstract":"Field-free molecular alignment can be induced by the strong ultrashort laser pulses. Here, the improvement of the alignment is completed by the coupled pulses of the ultrashort laser pulse and the strong broadband terahertz pulse. The gaseous CO molecules are aligned by such coupled pulses, and the evolution of its states are studied based on the rigid rotor approximation theory with the simulation method. The influences of the pulses parameters on the alignment are also discussed.","PeriodicalId":6852,"journal":{"name":"2021 46th International Conference on Infrared, Millimeter and Terahertz Waves (IRMMW-THz)","volume":"113 1","pages":"1-2"},"PeriodicalIF":0.0,"publicationDate":"2021-08-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80561113","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-08-29DOI: 10.1109/IRMMW-THz50926.2021.9566924
H. Richter, C. Buchbender, R. Güsten, R. Higgins, B. Klein, J. Stutzki, H. Wiesemeyer, H. Hübers
Atomic oxygen governs photochemistry and energy balance of the mesosphere and lower thermosphere of the Earth. Its concentration is extremely difficult to measure with remote sensing techniques since it has only few optically active transitions. Current indirect measurements involve photochemical models and the results are not always in agreement, particularly when obtained with different instruments. In addition, altitudes above 100 km are not covered by these methods. We report on direct measurements of the 4.7-THz fine-structure transition of atomic oxygen at 4.7448 THz using the German Receiver for Astronomy at Terahertz Frequencies on board the Stratospheric Observatory for Infrared Astronomy. Our measurements agree well with atmospheric models and satellite observations below 100 km.
{"title":"Observation of Atomic Oxygen in the Mesosphere and Thermosphere of Earth with the THz Heterodyne Spectrometer GREAT","authors":"H. Richter, C. Buchbender, R. Güsten, R. Higgins, B. Klein, J. Stutzki, H. Wiesemeyer, H. Hübers","doi":"10.1109/IRMMW-THz50926.2021.9566924","DOIUrl":"https://doi.org/10.1109/IRMMW-THz50926.2021.9566924","url":null,"abstract":"Atomic oxygen governs photochemistry and energy balance of the mesosphere and lower thermosphere of the Earth. Its concentration is extremely difficult to measure with remote sensing techniques since it has only few optically active transitions. Current indirect measurements involve photochemical models and the results are not always in agreement, particularly when obtained with different instruments. In addition, altitudes above 100 km are not covered by these methods. We report on direct measurements of the 4.7-THz fine-structure transition of atomic oxygen at 4.7448 THz using the German Receiver for Astronomy at Terahertz Frequencies on board the Stratospheric Observatory for Infrared Astronomy. Our measurements agree well with atmospheric models and satellite observations below 100 km.","PeriodicalId":6852,"journal":{"name":"2021 46th International Conference on Infrared, Millimeter and Terahertz Waves (IRMMW-THz)","volume":"86 1","pages":"1-2"},"PeriodicalIF":0.0,"publicationDate":"2021-08-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83707061","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-08-29DOI: 10.1109/IRMMW-THz50926.2021.9567261
A. Chernyadiev, D. But, C. Kołaciński, K. Ikamas, A. Lisauskas
An electrically tunable detector for sub-THz-frequency radiation based on Si CMOS technology is proposed. The tunability range of the implemented detector covers frequencies from 150 GHz up to 270 GHz with optical responsivity close to 1 kV/W and noise equivalent power below 20 ${text{pW}}/sqrt {{text{Hz}}} $. Potential applications include microwave bio and medical sensing, spectroscopy, amateur radio use and nondestructive imaging.
{"title":"Electrically tunable detector for millimeter frequency band","authors":"A. Chernyadiev, D. But, C. Kołaciński, K. Ikamas, A. Lisauskas","doi":"10.1109/IRMMW-THz50926.2021.9567261","DOIUrl":"https://doi.org/10.1109/IRMMW-THz50926.2021.9567261","url":null,"abstract":"An electrically tunable detector for sub-THz-frequency radiation based on Si CMOS technology is proposed. The tunability range of the implemented detector covers frequencies from 150 GHz up to 270 GHz with optical responsivity close to 1 kV/W and noise equivalent power below 20 ${text{pW}}/sqrt {{text{Hz}}} $. Potential applications include microwave bio and medical sensing, spectroscopy, amateur radio use and nondestructive imaging.","PeriodicalId":6852,"journal":{"name":"2021 46th International Conference on Infrared, Millimeter and Terahertz Waves (IRMMW-THz)","volume":"25 1","pages":"1-2"},"PeriodicalIF":0.0,"publicationDate":"2021-08-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79191933","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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