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Can GRB 250702B be explained as the tidal disruption of a white dwarf by an intermediate mass black hole? Yes
Get PDFGRB 250702B is a unique astrophysical transient characterised by its nature as a repeating gamma-ray trigger. Its properties include possible periodicity in its gamma-ray light curve, an X-ray counterpart that rose prior to the gamma-ray outbursts and faded quickly, and radio and infrared counterparts. These features are difficult to reconcile with most models of high energy transients but we show that they are compatible with a white dwarf bound to an intermediate mass black hole that is tidally stripped over multiple pericentre passages before being fully disrupted. In this model, accretion onto the black hole powers a mildly relativistic jet that produces the X-rays through internal processes and the infrared and radio counterparts through thermal emission and external shocks respectively but is unable to produce the gamma-ray emission on its own. We find that chaotic debris streams from the multiple stripping episodes can collide with a period roughly the same as the orbital period of the star. These shocks produce X-ray photons that are upscattered by the jet to produce the observed MeV gamma-ray emission. Future analysis of the jet properties will allow us to place firmer constraints on our model
Influence of Landscape and Lake Characteristics on Long-Term Water-Level Responses in Shallow Lakes of the Sub-Humid Boreal Plains, Canada
Get PDFShallow lakes are important ecosystems highly susceptible to water-level fluctuations and desiccation caused by climate cycles and anthropogenic pressures. To better predict and manage the impacts of disturbance we examined the natural variability over a 20-year period, that spans the range of long-term (decadal) weather cycles, and the controls on water-level deviation (WLD) of 26 shallow lakes that include all configurations of lake types and glacial landscapes typical in the Boreal Plains (BP) of Canada. Water budgets and hydrochemical analyses show that dominant lake water-budget components vary spatially and temporally with different geological settings and land covers that influence the scale and magnitude of lake-groundwater connectivity and surface-water inflow. However, over decadal weather cycles similar ranges in WLD were observed across all glacial geologies and shallow lake types. Lake geometry and evaporation interacted with lake-catchment characteristics to further impact the dynamics and memory of water levels to interannual and decadal weather patterns. In all lake-catchment types, lake bathymetry and outflow sill elevation determined overall storage which controls maximum water level elevation during wet years and extent of desiccation during drought years. This research demonstrates that in sub-humid glaciated continental landscapes, such as the BP, lake management strategies founded on lake permanence and fluctuation magnitudes are of limited value. Rather, focus should be placed on documenting the long-term WLD and considering the interaction of landscape characteristics and internal lake mechanisms that enable different lake types in such heterogeneous landscapes to recover and persist over decadal meteorological cycles.</p
The impact of inclusive electron ion collider data on the strong coupling determination in a global PDF fit
Get PDFWe present a study of the impact of data from the upcoming Electron Ion Collider (EIC) on the determination of the strong coupling within the context of the global MSHT fitting framework. To achieve this, we generate EIC electron-proton scattering pseudodata according to both conservative and optimistic experimental uncertainty projections and perform a simultaneous fit to obtain the proton PDFs and the value of the strong coupling. In the conservative case the impact is found to be moderate, but non-negligible, while in the optimistic case it is observed to be rather significant. These results therefore underline the promising potential for the EIC in the determination of the strong coupling. We in addition explore the impact of any potential tensions between the EIC data and the rest of the data in the global fit by injecting explicit inconsistencies into the pseudodata generation. This can lead to a noticeable bias in the extracted value of the strong coupling, highlighting the importance of accounting for all sources of theoretical uncertainty in the fit as well as the relevance of an enlarged, conservative, error definition in the determination of the strong coupling
The aging cornea: From mechanisms to clinical applications
No full textAging is a multifactorial process characterized by a gradual decline in function, increased susceptibility to diseases, and diminished regenerative capacity. As the primary refractive structure and barrier of the eye, the cornea undergoes significant structural and functional changes during aging, making individuals more prone to various ocular surface diseases. Key age-related corneal changes include epithelial thinning, stromal remodeling with increased collagen cross-linking, endothelial cell loss, and a decline in corneal nerve density and function. These changes are driven by core aging mechanisms such as genomic instability, telomere shortening, mitochondrial dysfunction, cellular senescence, impaired autophagy, stem cell exhaustion, and chronic inflammation. This review systematically explores the clinical manifestations, molecular mechanisms, and potential therapeutic approaches for corneal aging, providing a scientific basis for delaying corneal aging, maintaining ocular health, and preserving visual function
Mesenchymal stem/stromal cell secretomes generated in serum free conditions and on clinically relevant plasma polymerized membranes promote fibroblast wound healing activity
No full textBACKGROUND/AIMS: Mesenchymal stem/stromal cells (MSCs) are known to secrete wound healing factors. However, the delivery of the MSCs and their secretomes remains a barrier to the development of a successful regenerative medicine. Therefore, we examined the content and paracrine activity of serum free MSC conditioned media (MSC CM) generated in routine tissue culture and when cultured on a plasma polymerized membrane previously used clinically in cell therapies for skin wounds.METHODS: Serum free MSC CM from murine and human MSC cultures were subjected to proteomic analysis by mass spectrometry and quantitative immunoassays and their paracrine effects were tested on dermal fibroblasts in vitro.RESULTS: MSC CM contained multiple wound healing factors, including extracellular matrix proteins and soluble factors. MSC CM harvested from flask cultures and plasma polymerized membrane cultures significantly increased dermal fibroblast adhesion, proliferation, and scratch wound closure (for mouse MSC CM) compared to control media.CONCLUSION: This study has: (i) shown that MSC secreted factors increased dermal fibroblast activities seen in wound healing; (ii) identified target factors potentially responsible for these paracrine effects; (iii) shown that MSC secretomes generated on a plasma polymerized membrane used in skin cell therapies also have wound healing paracrine effects.</p
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