In high-temperature superconductivity, the process that leads to the formation of Cooper pairs, the fundamental charge carriers in any superconductor, remains mysterious. We used a femtosecond laser pump pulse to perturb superconducting Bi(2)Sr(2)CaCu(2)O(8+δ) and studied subsequent dynamics using time- and angle-resolved photoemission and infrared reflectivity probes. Gap and quasiparticle population dynamics revealed marked dependencies on both excitation density and crystal momentum. Close to the d-wave nodes, the superconducting gap was sensitive to the pump intensity, and Cooper pairs recombined slowly. Far from the nodes, pumping affected the gap only weakly, and recombination processes were faster. These results demonstrate a new window into the dynamical processes that govern quasiparticle recombination and gap formation in cuprates.
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http://dx.doi.org/10.1126/science.1217423 | DOI Listing |
Nat Mater
January 2025
School of Physics, Zhejiang University, Hangzhou, China.
In ordered magnets, the elementary excitations are spin waves (magnons), which obey Bose-Einstein statistics. Similarly to Cooper pairs in superconductors, magnons can be paired into bound states under attractive interactions. The Zeeman coupling to a magnetic field is able to tune the particle density through a quantum critical point, beyond which a 'hidden order' is predicted to exist.
View Article and Find Full Text PDFHomozygous MTAP deletion occurs in ~15% of cancers, making them vulnerable to decreases in the concentration of S-adenosylmethionine (SAM). AG-270/S095033 is an oral, potent, reversible inhibitor of methionine adenosyltransferase 2 A (MAT2A), the enzyme primarily responsible for the synthesis of SAM. We report results from the first-in-human, phase 1 trial of AG-270/S095033 as monotherapy in patients with advanced malignancies (ClinicalTrials.
View Article and Find Full Text PDFData Brief
February 2025
Department of Medicine, Division of Cardiovascular Diseases, Washington University School of Medicine in St. Louis, St. Louis, MO, United States.
Commun Med (Lond)
December 2024
Department of Cardiovascular Medicine, Mayo Clinic, Rochester, MN, USA.
Background: Wide QRS complex tachycardia (WCT) differentiation into ventricular tachycardia (VT) and supraventricular wide complex tachycardia (SWCT) remains challenging despite numerous 12-lead electrocardiogram (ECG) criteria and algorithms. Automated solutions leveraging computerized ECG interpretation (CEI) measurements and engineered features offer practical ways to improve diagnostic accuracy. We propose automated algorithms based on (i) WCT QRS polarity direction (WCT Polarity Code [WCT-PC]) and (ii) QRS polarity shifts between WCT and baseline ECGs (QRS Polarity Shift [QRS-PS]).
View Article and Find Full Text PDFAdv Mater
December 2024
Academy for Advanced Interdisciplinary Studies and Department of Physics, Southern University of Science and Technology (SUSTech), Shenzhen, 518055, P. R. China.
Concurrent superconductivity and negative photoconductivity (NPC) are rarely observed. Here, the discovery in PbSeTe of superconductivity and photoconductivity transitions between positive photoconductivity (PPC) and NPC during compression is reported to ≈40 GPa and subsequent decompression, which are also accompanied by reversible structure transitions (3D Fm m ⇌ 2D Pnma ⇌ 3D Pm m). Superconductivity with a maximum T of ≈6.
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