All 3,266,244 Page 51/326,625
-
2025
Abstract
We investigate the sensitivity of the 21 cm power spectrum from cosmic dawn and the epoch of reionization to models of free-streaming dark radiation (parameterized through N
eff) and interacting dark radiation-dark matter models (DM-DR). The latter models have gained attention for their potential in addressing recent cosmological tensions and structure formation challenges.
We perform a Fisher matrix analysis under different assumptions regarding the astrophysical modeling, and forecast the sensitivity of HERA observations, combined with CMB data from Planck and the Simons Observatory (SO), to N
eff and DM-DR interaction modeled using the ETHOS framework assuming a constant scattering rate between the two components.
Most importantly, we find that 21 cm observations can improve the sensitivity to the DM-DR interaction rate by up to four order of magnitude compared to Planck and SO. Conversely, in the limit of low interaction rate (which asymptotically matches N
eff), CMB data dominates the constraining power, but the inclusion of HERA data can provide a ∼ 20% improvement in sensitivity over CMB data alone.
Moreover, we find that HERA observations will be able to probe a region of the DM-DR interaction parameter space which is promising to explain the weak lensing amplitude `S
8' tension. Our results demonstrate the complementarity of 21 cm and CMB data in exploring dark sector interactions.- Book : 2025(01)
- Pub. Date : 2025
- Page : pp.071-071
- Keyword :
-
2025
- Book : ()
- Pub. Date : 2025
- Page :
- Keyword :
-
2025
- Book : ()
- Pub. Date : 2025
- Page :
- Keyword :
-
2025
- Book : ()
- Pub. Date : 2025
- Page :
- Keyword :
-
2025
- Book : ()
- Pub. Date : 2025
- Page :
- Keyword :
-
2025
- Book : ()
- Pub. Date : 2025
- Page :
- Keyword :
-
2025
- Book : ()
- Pub. Date : 2025
- Page :
- Keyword :
-
2025
Conjunctival lymphangiectasia is a rare ocular condition marked by abnormal lymphatic duct enlargement, leading to the collection of lymph in interconnecting channels in the conjunctiva. It can be primary (from congenital issues) or secondary (due to lymphatic vessel blockage from factors like radiation or surgery). In our case, a 64-year-old man had a history of persistent eye discomfort and persistent foreign-body sensation, which was his main cause of concern. On examination, he had evidence of cystic channels with clear fluid (lymph) in both eyes. Anterior segment optical coherence tomography confirmed interconnecting fluid-filled cysts in both eyes.- Book : 13(1)
- Pub. Date : 2025
- Page : pp.125-126
- Keyword :
-
2025
Abstract
Allosteric regulation is a powerful mechanism for controlling the efficiency of enzymes. Deciphering the evolutionary mechanisms by which allosteric properties have been acquired in enzymes is of fundamental importance. We used the malate (MalDH) and lactate deydrogenases (LDHs) superfamily as model to elucidate this phenomenon. By introducing a few of mutations associated to the emergence of allosteric LDHs into the non-allosteric MalDH from Methanopyrus kandleri, we have gradually shifted its enzymatic profile toward that typical of allosteric LDHs. We first investigated the process triggering homotropic activation. The structures of the resulting mutants show the typical compact organization of the R-active state of LDHs, but a distorted (T-like) catalytic site demonstrating that they corresponds to hybrid states. Molecular dynamics simulations and free energy calculations confirmed the capability of these mutants to sample the T-inactive state. By adding a final single mutation to fine-tune the flexibility of the catalytic site, we obtained an enzyme with both sigmoid (homotropic) and hyperbolic (heterotropic) substrate activation profiles. Its structure shows a typical extended T-state as in LDHs, whereas its catalytic state has as a restored configuration favorable for catalysis. Free energy calculations indicate that the T and R catalytic site configurations are in an equilibrium that depends on solvent conditions. We observed long-range communication between monomers as required for allosteric activation. Our work links the evolution of allosteric regulation in the LDH/MDH superfamily to the ensemble model of allostery at molecular level, and highlights the important role of the underlying protein dynamics.- Book : 42(1)
- Pub. Date : 2025
- Page :
- Keyword :
-
2025
- Book : ()
- Pub. Date : 2025
- Page :
- Keyword :
