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Identifying Present-Biased Discount Functions in Dynamic Discrete Choice Models
Jaap H. Abbring, {\O}ystein Daljord, Fedor Iskhakov
https://arxiv.org/abs/2507.07286

Identifying Present-Biased Discount Functions in Dynamic Discrete Choice Models
We study the identification of dynamic discrete choice models with sophisticated, quasi-hyperbolic time preferences under exclusion restrictions. We consider both standard finite horizon problems and empirically useful infinite horizon ones, which we prove to always have solutions. We reduce identification to finding the present-bias and standard discount factors that solve a system of polynomial equations with coefficients determined by the data and use this to bound the cardinality of the ide…

XL-Calibur Polarimetry of Cyg X-1 Further Constrains the Origin of its Hard-state X-ray Emission
Hisamitsu Awaki, Matthew G. Baring, Richard Bose, Jacob Casey, Sohee Chun, Adrika Dasgupta, Pavel Galchenko, Ephraim Gau, Kazuho Goya, Tomohiro Hakamata, Takayuki Hayashi, Scott Heatwole, Kun Hu, Daiki Ishi, Manabu Ishida, Fabian Kislat, M\'ozsi Kiss, Kassi Klepper, Henric Krawczynski, Haruki Kuramoto, Lindsey Lisalda, Yoshitomo Maeda, Hironori Matsumoto, Shravan Vengalil Menon, Aiko Mi…

XL-Calibur Polarimetry of Cyg X-1 Further Constrains the Origin of its Hard-state X-ray Emission
The balloon-borne hard X-ray polarimetry mission XL-Calibur observed the Black Hole X-ray Binary (BHXRB) Cygnus X-1 (Cyg X-1) during its nearly six-day Long Duration Balloon (LDB) flight from Sweden to Canada in July 2024. The XL-Calibur observations allowed us to derive the most precise constraints to date of the Polarization Degree (PD) and Polarization Angle (PA) of the hard X-ray emission from a BHXRB. XL-Calibur observed Cyg X-1 in the hard state and measured a $\sim$19-64 keV PD of ($5.0^…

Beam Squint Mitigation in Wideband Hybrid Beamformers: Full-TTD, Sparse-TTD, or Non-TTD?
Mehdi Monemi, Mehdi Rasti, Omid Yazdani, Onel Lopez, Matti Latva-aho
https://arxiv.org/abs/2506.19381

Beam Squint Mitigation in Wideband Hybrid Beamformers: Full-TTD, Sparse-TTD, or Non-TTD?
Beam squint poses a fundamental challenge in wideband hybrid beamforming, particularly for mmWave and THz systems that demand both ultra-wide bandwidth and high directional beams. While conventional phase shifter-based beamformers may offer partial mitigation, True Time Delay (TTD) units provide a fundamentally more effective solution by enabling frequency-independent beam steering. However, the high cost of TTD units has recently driven much interest in Sparse-TTD architectures, which combine …