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result(s) for
"Yao, Da-Zhi"
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Multiwavelength Observations of the Apparently Nonrepeating FRB 20250316A
The physical origin of fast radio bursts (FRBs) remains uncertain. Although multiwavelength observations have been widely conducted, only Galactic FRB 20200428D is associated with an X-ray burst from the magnetar SGR J1935+2154. Here we present multiwavelength follow-up observations of the nearby bright FRB 20250316A, including the Five-hundred-meter Aperture Spherical radio Telescope (FAST), Einstein Probe (EP) X-ray mission, Chandra X-ray Observatory, Wide Field Survey Telescope (WFST), and Space Variable Objects Monitor/Visible Telescope (SVOM/VT). The 13.08 hr FAST follow-up campaign without pulse detection requires an energy distribution flatter than those of well-known repeating FRBs, suggesting that this burst is likely a one-off event. A prompt EP follow-up and multiepoch observational campaign totaling >100 ks led to the detection of an X-ray source within the angular resolution of its Follow-up X-ray Telescope (FXT; 10″). A subsequent Chandra observation revealed this source to be offset by 7″ from the FRB position and established a 0.5–10 keV flux upper limit of 7.6 × 10−15 erg cm−2 s−1 at the FRB position, corresponding to ∼1039 erg s−1 at the 40 Mpc distance of the host galaxy NGC 4141. These results set one of the most stringent limits on X-ray emission from a nonrepeating FRB, disfavoring ultraluminous X-ray sources as counterparts of apparently one-off FRBs and offering critical insights into afterglow models. Our study suggests that an arcsecond localization of both the FRB and its potential X-ray counterpart is essential for exploring the X-ray counterpart of an FRB.
Journal Article
Changes in lake area and water level in response to hydroclimate variations in the source area of the Yellow River: a case study from Lake Ngoring
In the north-eastern Qinghai-Tibet Plateau (QTP), the source area of the Yellow River (SAYR) has been experiencing significant changes in climatic and environmental conditions in recent decades. To date, few studies have combined modern hydrological conditions with paleoclimate records to explore the mechanism(s) of these changes. This study seeks to improve understanding of hydrological variability on decadal and centennial timescales in the SAYR and to identify its general cause. We first determined annual fluctuations in the surface area of Lake Ngoring from 1985 to 2020 using multi-temporal Landsat images. The results show that lake surface area changes were generally consistent with variations in precipitation, streamflow and the regional dry-wet index in the SAYR, suggesting that the water balance of the Lake Ngoring area is closely associated with regional hydroclimate changes. These records are also comparable to the stalagmite δ 18O monsoon record, as well fluctuations in the Southern Oscillation Index (SOI). Moreover, an association of high TSI (total solar insolation) anomalies and sunspot numbers with the expansion of Lake Ngoring surface area is observed, implying that solar activity is the key driving factor for hydrologic variability in the SAYR on a decadal timescale. Following this line of reasoning, we compared the δ 13C org-based lake level fluctuations of Lake Ngoring for the last millennium, as previously reported, with the hydroclimatic history and the reconstructed TSI record. We conclude that the hydrological regime of Lake Ngoring has been mainly controlled by centennial fluctuations in precipitation for the last millennium, which is also dominated by solar activity. In general, it appears that solar activity has exerted a dominant influence on the hydrological regime of the SAYR on both decadal and centennial timescales, which is clearly manifested in the variations of lake area and water level of Lake Ngoring.
Journal Article
Precipitation Strengthening by Nanometer-sized Carbides in Hot-rolled Ferritic Steels
The mechanical properties of the hot-rolled plates of Ti steel and Ti-Mo steel after isothermal transformation in a temperature range of 600 700 ℃ for 60 min have been tested, and the microstructures of the matrix and the characteristics of precipitated nanometer-sized carbides have also been examined by scanning electron microscopy and transmission electron microscopy. The precipitation regularity of nanometer-sized carbides has been studied by thermodynamic method and the contributions of corresponding strengthening mechanisms to the total yield strength have been calculated. The tensile strength of hot-rolled Ti-Mo ferritie steel can achieve 780 MPa with an elongation of 20.0% after being isothermally treated at 600 ℃ for 60 rain, and the tensile strength of Ti steel is 605 MPa with an elongation of 22.7%, according to the results of tensile tests. The critical nucleation size of （Ti,Mo）C is smaller than that of TiC at a given isothermal temperature, but the nucleation rate of （Ti, Mo）C is larger than that of TiC. The grainrefinement strengthening and precipitation strengthening contribute the main amount of the total yield strength. The major increase in yield strength with the decrease of isothermal temperature results from the contribution of precipi tation strengthening. The contribution of precipitation strengthening to the yield strength of the steels has been esti mated. The ferrite phase can be strengthened by about 400 MPa through precipitation strengthening in Ti-Mo steel isothermally treated at 600 ℃ for 60 rain, which is about 200 MPa higher than that of Ti steel under the same conditions.
Journal Article
GRB 240529A: A Tale of Two Shocks
Thanks to the rapidly increasing time-domain facilities, we are entering a golden era of research on gamma-ray bursts (GRBs). In this Letter, we report our observations of GRB 240529A with the Burst Optical Observer and Transient Exploring System, the 1.5 m telescope at Observatorio de Sierra Nevada, the 2.5 m Wide Field Survey Telescope of China, the Large Binocular Telescope, and the Telescopio Nazionale Galileo. The prompt emission of GRB 240529A shows two comparable energetic episodes separated by a quiescence time of roughly 400 s. Combining all available data on the GRB Coordinates Network, we reveal the simultaneous apparent X-ray plateau and optical rebrightening around 103–104 s after the burst. Rather than the energy injection from the magnetar as widely invoked for similar GRBs, the multiwavelength emissions could be better explained as two shocks launched from the central engine separately. The optical peak time and our numerical modeling suggest that the initial bulk Lorentz factor of the later shock is roughly 50, which indicates that the later jet should be accretion driven and have a higher mass loading than a typical one. The quiescence time between the two prompt emission episodes may be caused by the transition between different accretion states of a central magnetar or black hole, or the fallback accretion process. A sample of similar bursts with multiple emission episodes in the prompt phase and sufficient follow-up could help to probe the underlying physics of GRB central engines.
Journal Article
Multiwavelength Observations of the Apparently Non-repeating FRB 20250316A
The physical origin of fast radio bursts (FRBs) remains uncertain. Although multiwavelength observations have been widely conducted, only Galactic FRB~20200428D is associated with an X-ray burst from the magnetar SGR J1935+2154. Here, we present multiwavelength follow-up observations of the nearby bright FRB~20250316A, including the Five-hundred-meter Aperture Spherical radio Telescope (FAST), Einstein Probe (EP) X-ray mission, Chandra X-ray Observatory, Wide Field Survey Telescope (WFST) and Space Variable Object Monitor/Visible Telescope (SVOM/VT). The 13.08-hour FAST follow-up campaign without pulse detection requires an energy distribution flatter than those of well-known repeating FRBs, suggesting that this burst is likely a one-off event. A prompt EP follow-up and multi-epoch observational campaign totaling \\(>\\) 100 ks led to the detection of an X-ray source within the angular resolution of its Follow-up X-ray Telescope (FXT, \\(10^\\)). A subsequent Chandra observation revealed this source to be offset by \\(7^\\) from the FRB position, and established a 0.5-10 keV flux upper limit of \\(7.6 10^-15\\) \\( erg\\,cm^-2\\,s^-1\\) at the FRB position, corresponding to \\( 10^39\\) \\( erg\\,s^-1\\) at the 40 Mpc distance of the host galaxy NGC~4141. These results set one of the most stringent limits on X-ray emission from a non-repeating FRB, disfavoring ultra-luminous X-ray sources (ULXs) as counterparts of apparently one-off FRBs and offering critical insights into afterglow models. Our study suggests that an arcsecond localization of both the FRB and its potential X-ray counterpart is essential for exploring the X-ray counterpart of an FRB.
Paper
Large-scale and high-resolution mass spectrometry-based proteomics profiling defines molecular subtypes of esophageal cancer for therapeutic targeting
Esophageal cancer (EC) is a type of aggressive cancer without clinically relevant molecular subtypes, hindering the development of effective strategies for treatment. To define molecular subtypes of EC, we perform mass spectrometry-based proteomic and phosphoproteomics profiling of EC tumors and adjacent non-tumor tissues, revealing a catalog of proteins and phosphosites that are dysregulated in ECs. The EC cohort is stratified into two molecular subtypes—S1 and S2—based on proteomic analysis, with the S2 subtype characterized by the upregulation of spliceosomal and ribosomal proteins, and being more aggressive. Moreover, we identify a subtype signature composed of ELOA and SCAF4, and construct a subtype diagnostic and prognostic model. Potential drugs are predicted for treating patients of S2 subtype, and three candidate drugs are validated to inhibit EC. Taken together, our proteomic analysis define molecular subtypes of EC, thus providing a potential therapeutic outlook for improving disease outcomes in patients with EC.
Proteomics can aid in the identification of molecular subtypes in cancers. Here, the authors perform proteomic profiling of 124 paired oesophageal cancer and adjacent non-tumour tissues and identify two subtypes that are associated with patient survival for therapeutic targeting.
Journal Article
A defect in mitochondrial protein translation influences mitonuclear communication in the heart
The regulation of the informational flow from the mitochondria to the nucleus (mitonuclear communication) is not fully characterized in the heart. We have determined that mitochondrial ribosomal protein S5 (MRPS5/uS5m) can regulate cardiac function and key pathways to coordinate this process during cardiac stress. We demonstrate that loss of
Mrps5
in the developing heart leads to cardiac defects and embryonic lethality while postnatal loss induces cardiac hypertrophy and heart failure. The structure and function of mitochondria is disrupted in
Mrps5
mutant cardiomyocytes, impairing mitochondrial protein translation and OXPHOS. We identify
Klf15
as a
Mrps5
downstream target and demonstrate that exogenous
Klf15
is able to rescue the overt defects and re-balance the cardiac metabolome. We further show that
Mrps5
represses
Klf15
expression through c-myc, together with the metabolite L-phenylalanine. This critical role for
Mrps5
in cardiac metabolism and mitonuclear communication highlights its potential as a target for heart failure therapies.
The heart requires high levels of mitochondria to sustain function, and mitochondrial stressors can be transmitted to the nucleus and reprogram metabolism. Here, the authors show that a mitochondrial ribosomal protein is important for heart development in mice by increasing nuclear Klf15 expression.
Journal Article
Intercalated disc protein Xinβ is required for Hippo-YAP signaling in the heart
Intercalated discs (ICD), specific cell-to-cell contacts that connect adjacent cardiomyocytes, ensure mechanical and electrochemical coupling during contraction of the heart. Mutations in genes encoding ICD components are linked to cardiovascular diseases. Here, we show that loss of Xinβ, a newly-identified component of ICDs, results in cardiomyocyte proliferation defects and cardiomyopathy. We uncovered a role for Xinβ in signaling via the Hippo-YAP pathway by recruiting NF2 to the ICD to modulate cardiac function. In
Xinβ
mutant hearts levels of phosphorylated NF2 are substantially reduced, suggesting an impairment of Hippo-YAP signaling. Cardiac-specific overexpression of YAP rescues cardiac defects in
Xinβ
knock-out mice—indicating a functional and genetic interaction between Xinβ and YAP. Our study reveals a molecular mechanism by which cardiac-expressed intercalated disc protein Xinβ modulates Hippo-YAP signaling to control heart development and cardiac function in a tissue specific manner. Consequently, this pathway may represent a therapeutic target for the treatment of cardiovascular diseases.
Intercalated discs ensure mechanical and electrochemical coupling during contraction of the heart. Here, the authors show that loss of Xinβ results in cardiomyocyte proliferation defects and cardiomyopathy by influencing the Hippo-YAP signalling pathway, thus affecting cardiac development and function.
Journal Article