Search Results (213)

We present the results of long-term photometric and spectroscopic monitoring of the Seyfert galaxy NGC 4151 based on new observational data complemented by archival material spanning several decades. NGC 4151 is one of the most extensively studied active galactic nuclei, exhibiting pronounced variability in both optical continuum and emission-line fluxes, which makes it a key object for investigating physical processes in the central engine and the broad-line region. Our study covers the optical and near-infrared wavelength ranges, including the Ic band and the standard BVRc photometric filters. Using multi-band optical photometry and optical spectroscopy, we construct light curves of the continuum and emission lines and perform a comparative analysis of their temporal behavior during different activity states of the galaxy. The analysis focuses on variability amplitudes, long-term trends, and correlations between photometric and spectral characteristics, allowing us to examine the relationship between continuum variations and the line-emitting regions. Full article

NUSES is a pathfinder satellite that will be deployed in a low Earth orbit, designed with new technologies for space-based detectors. Ziré is one of the payloads of NUSES and aims to measure the spectra of electrons, protons, and light nuclei in a kinetic energy range spanning from a few MeVs to several hundred MeVs, as well as photons in the energy range from 0.1 MeV to 30 MeV. Ziré consists of a Fiber TracKer (FTK), a Plastic Scintillator Tower (PST), a calorimeter (CALOg), an AntiCoincidence System (ACS) and a Low Energy Module (LEM). The FTK is based on thin scintillating fibers read out by Silicon Photomultiplier (SiPM) arrays. We assembled a prototype of Ziré (Zirettino) equipped with a single FTK layer, a reduced number of PST layers and a partially instrumented CALOg. A preliminary version of the Ziré custom Front-End Board (FEB) featuring the on-the-shelf ASIC CITIROC by OMEGA/Weeroc was used for the readout. We carried out several beam test campaigns at CERN’s PS facility and a dynamic qualification test. The performance of FTK will be presented and discussed. Full article

Black carbon (BC), as a potent light-absorbing aerosol, is mainly removed from the atmosphere through wet deposition. The efficiency of this process depends on the capacity of BC particles to serve as cloud condensation nuclei (CCN) or ice nuclei (IN). Newly emitted BC particles are typically small in size and highly hydrophobic, which limits their activation potential. However, atmospheric aging processes involving interactions with sulfates, nitrates, or organic matter enhance their hydrophilicity and nucleation capacity. Particle size serves as the critical link between aging and removal processes. Larger or coated BC particles are more readily activated and removed, while smaller particles require higher supersaturation levels. Both observations and models indicate that uncertainties in BC particle size distribution and aging processes lead to significant discrepancies in lifetime and transport estimates. This paper reviews recent research on the size dependence of wet removal of BC, evaluates current observational and modeling results, and proposes key research priorities to more accurately constrain its role in the climate system. Full article

Background/Objectives: The cerebellum is essential for motor coordination and has recently been implicated in sleep-related disorders. However, the neural mechanisms linking sleep disruption to motor dysfunction remain poorly understood. This study aimed to elucidate the roles of the deep cerebellar nuclei (DCN), particularly the lateral nucleus, in motor dysfunction induced by chronic sleep disruption (CSD). Methods: Using a validated mouse model of CSD with periodic sleep fragmentation induced by an orbital shaker during the light phase, we assessed neuronal activation via c-Fos immunostaining and performed chemogenetic manipulation of glutamatergic neurons within the lateral nucleus. Behavioral performance was evaluated using open-field and rotarod tests. Results: CSD selectively increased c-Fos expression in the lateral nucleus, with no significant changes observed in other DCN subregions. Chemogenetic activation or ablation of glutamatergic neurons in the lateral nucleus decreased locomotor activity in the open-field test and shortened latency to fall in the rotarod task. Conversely, chemogenetic inhibition of these neurons attenuated CSD-induced impairments, restoring locomotor performance toward control levels. Conclusions: Our findings provide direct experimental evidence that glutamatergic neurons in the lateral nucleus play a crucial role in mediating CSD-induced motor dysfunction. These results highlight the cerebellar contribution to the interplay between sleep and motor control and identify a potential target for therapeutic intervention in sleep-related motor disorders. Full article

The fact that strange sea quarks are abundant in the nucleons, but with zero net strangeness, is of great importance for understanding the nature of matter condensed by strong interaction, particularly in the context of the “gigantic nucleus” created after the gravitational collapse of an evolved massive star. We hypothesize that the basic unit of bulk strong matter with the approximately light-flavored symmetry of valence quarks is “strangeon”, which is the counterpart of the nucleon found in atomic nuclei. In addition to strangeon stars (SnSs) with a large baryon number of $A\approx {10}^{57}$, strange nuggets (SnNs) with $A\gtrsim {10}^{10}$ could also exist in the universe. Both the SnSs and the SnNs are explained, with particular focus on the evidence obtained from observation and detection. Full article

We present a freeze-out approach for describing the formation of heavy elements in expanding nuclear matter. Applying concepts used in modeling heavy-ion collisions or ternary fission, we determine the abundances of heavy elements taking into account in-medium effects such as Pauli blocking and the Mott effect, which describes the dissolution of nuclei at high densities of nuclear matter. With this approach, we search for a universal initial distribution in a quasi-equilibrium state from which the coarse-grained pattern of the solar abundances of heavy elements freezes out and evolves by radioactive decay of the excited states. The universal initial state is characterized by the Lagrange parameters, which are related to temperature and chemical potentials of neutrons and protons. We show that such a state exists and determine a temperature of 5.266 MeV, a neutron chemical potential of 940.317 MeV and a proton chemical potential of 845.069 MeV, with a baryon number density of 0.013 fm⁻³ and a proton fraction of $0.13$. Heavy neutron-rich nuclei such as the hypothetical double-magic nucleus ³⁵⁸Sn appear in the initial distribution and contribute to the observed abundances after fission. We discuss astrophysical scenarios for the realization of this universal initial distribution for heavy-element nucleosynthesis, including supernova explosions, neutron star mergers and the inhomogeneous Big Bang. The latter scenario may be of interest in the light of early massive objects observed with the James Webb Space Telescope and opens new perspectives on the universality of the observed r-process patterns and the lack of observations of population III stars. Full article

In this study, we investigate the phase transition process during high-alumina, low-lithium glass-ceramics (ZnO-MgO-Li₂O-SiO₂-Al₂O₃) crystallization. The differential scanning calorimetry and high-temperature X-ray diffraction results show that approximately 10 wt.% of (Zn, Mg)Al₂O₄ crystals precipitated when the heat treatment temperature reached 850 °C, indicating that a large number of nuclei had already formed during the earlier stages of heat treatment. Field emission transmission electron microscopy used to observe the microstructure of glass-ceramics after staged heat treatment revealed that cation migration occurred during the nucleation process. Zn and Mg aggregated around Al to form (Zn, Mg)Al₂O₄ nuclei, which provided sites for crystal growth. Moreover, high-valence Zr aggregated outside the glass network, leading to the formation of nanocrystals. Raman spectroscopy analysis of samples at different stages of crystallization revealed that during spinel precipitation, the Q³ and Q⁴ structural units in the glass network increased significantly, along with an increase in the number of bridging oxygens. Highly coordinated Al originally present in the network mainly participated in spinel nucleation, effectively suppressing the subsequent formation of Li_xAl_xSi_1−xO₂, which eventually resulted in the successful preparation of glass-ceramics with (Zn, Mg)Al₂O₄ and ZrO₂ as the main crystalline phases. The grains in this glass-ceramic are all nanocrystals. Its Vickers hardness and flexural strength can reach up to 875 Hv and 350 MPa, respectively, while the visible light transmittance of the glass-ceramic reaches 81.5%. This material shows potential for applications in touchscreen protection, aircraft and high-speed train windshields, and related fields. Full article

Background/Objectives: The neuromuscular junction (NMJ) is the area where peripheral nerves communicate with muscle tissue. Muscle injury can occur as part of an acute degenerative process at the NMJ. This study aims to investigate the remodeling of the NMJ after a muscle injury in an experimental model. Methods: We used sixty male Wistar rats divided into five groups: a control group (C) and four muscle injury groups (MI) at different time points: 0 h, 24 h, 48 h, and 7 d after injury. We subjected the right hind limb to muscle injury and dissected the gastrocnemius muscles for analysis. We employed light microscopy to examine cell nuclei and the connective tissue, immunostaining to identify and measure the pre- and postsynaptic regions as well as calcium channels (P/Q), and real-time PCR to assess the gene expression of NRG1 and Agrin. Results: Our findings revealed an accumulation of nuclei and connective tissue in the acute injury groups (0 to 48 h). The morpho-quantitative analyses showed that the presynaptic structures and calcium channels underwent similar remodeling due to their morpho-functional relationship. Meanwhile, the postsynaptic receptors were significantly affected by the degenerative and inflammatory processes. These results can be linked to increased expression of NRG1 and Agrin in the acute injury groups. Conclusions: In conclusion, the synaptic regions displayed substantial adaptations within the first 48 h, with the presynaptic region recovering rapidly and the postsynaptic region recovering slowly. This relationship suggests that significant increases in Agrin and NRG1 play a crucial role in maintaining the integrity of these structures. Full article

A comparative analysis of the photometric variability of the blazar 3C 273 and the quasar PDS 456 using multi-band data from ground- and space-based platforms (2015–2025) reveals contrasting behaviors. For 3C 273, a statistically significant secular dimming was detected in the ATLASc-band light curve $\left((5.6\pm 0.2)\times {10}^{-4}\mathrm{mag}{\mathrm{day}}^{-1}\right)$ and confirmed by Johnson–Cousins V-band photometry. Ten optical flares were identified, two coinciding with Fermi gamma-ray enhancements, suggesting a synchrotron origin linked to jet activity. A significant bluer-when-brighter trend ($\rho =-0.54$) was found relative to the o-band, and several color extrema align with gamma-ray activity, reinforcing the nonthermal interpretation. In contrast, PDS 456 exhibits a statistically significant secular brightening in the o-band $\left((-3.1\pm 0.2)\times {10}^{-5}\mathrm{mag}{\mathrm{day}}^{-1}\right)$ and 75 optical flares, four coinciding with UV flares observed by Swift/UVOT. The $c–o$ color index displays a non-Gaussian distribution with asymmetric reddening and blueing episodes. An extreme reddening event aligns with a strong UV flare, suggesting transient inner-disk heating. These results indicate jet-dominated variability in 3C 273 and disk-driven variability in PDS 456, highlighting distinct physical mechanisms in radio-loud versus radio-quiet active galactic nuclei. Full article

We present extensive comparisons of ¹⁶O+¹⁶O collisions at a center-of-mass energy per nucleon pair $\sqrt{s_{NN}}=200$ GeV and ²⁰⁸Pb+¹⁶O collisions at $\sqrt{s_{NN}}=68.5$ GeV as well as ²⁰Ne+²⁰Ne collisions at $\sqrt{s_{NN}}=200$ GeV and ²⁰⁸Pb+²⁰Ne collisions at $\sqrt{s_{NN}}=68.5$ GeV based on a multiphase transport (AMPT) model. We recommend measuring the ratio of the elliptic flow to the triangular flow, which shows appreciable sensitivity to the structure of light nuclei, as also found in other studies. This is especially so if the observable is measured near the target rapidity in ²⁰⁸Pb+¹⁶O or ²⁰⁸Pb+²⁰Ne collisions, as originally found in the present study. Our study serves as a useful reference for understanding the effect of structure on observables in collisions involving light nuclei under analysis or on the schedule. Full article

In mammals, the suprachiasmatic nucleus (SCN), located in the hypothalamus serves as the master biological clock and precisely regulates circadian rhythms through a complex network structure. As a central pacemaker, the SCN has two primary functions: one is to synchronize the daily rhythms in physiological and behavioral activities; the other is to entrain the endogenous rhythms to the external light–dark cycle. A deep understanding of the SCN network structure is crucial for elucidating the functional mechanisms of the biological clock system. In this review, we systematically summarized the impact of the SCN network structure on functional regulation under light stimulation based on mathematical models. Studies have shown that the coupling between the light-sensitive subgroups in the left and right nuclei of the SCN can enhance the entrainment ability. As an integrated network structure, the SCN may have the characteristics of the small-world network or the scale-free network, as these properties are more conducive to the realization of functions. Additionally, the higher-order coupling mechanism within the SCN can effectively expand the entrainment range. These theoretical research results offer new insights into the relationship between the SCN network and functions and provide crucial theoretical guidance and validation directions for subsequent experimental research. Full article

Ultra-high-energy cosmic rays (UHECRs) with energies exceeding ${10}^{19}$ eV are believed to originate from extragalactic environments, potentially associated with relativistic jets in active galactic nuclei (AGN). Among AGNs, blazars, particularly those detected in very-high-energy (VHE) gamma rays, are promising candidates for UHECR acceleration and high-energy neutrino production. In this work, we investigate three blazar sources, AP Librae, 1H 1914–194, and PKS 0735+178, using multiwavelength spectral energy distribution (SED) modeling. These sources span a range of synchrotron peak classes and redshifts, providing a diverse context to explore the physical conditions in relativistic jets. We employ both leptonic and lepto-hadronic models to describe their broadband emission from radio to TeV energies, aiming to constrain key jet parameters such as magnetic field strength, emission region size, and particle energy distributions. Particular attention is given to evaluating their potential as sources of UHECRs and high-energy neutrinos. Our results shed light on the complex interplay between particle acceleration mechanisms, radiative processes, and multi-messenger signatures in extreme astrophysical environments. Full article

The presence of Active Galaxy Nuclei (AGN) can affect the morphological classification of galaxies. This work aims to determine how the contribution of AGN affects the most-used morphological parameters down to the redshift of z ∼ 2 in COSMOS-like conditions. We use a sample of >2000 local non-active galaxies, with a well-known visual morphological classification, and add an AGN as an unresolved component that contributes to the total galaxy flux with 5–75%. We moved all the galaxies to lower magnitudes (higher redshifts) to map the conditions in the COSMOS field, and we measured six morphological parameters. The greatest impact on morphology occurs when considering the combined effect of magnitude, redshift, and AGN, with spiral galaxies being the most affected. In general, all the concentration parameters change significantly if the AGN contribution is >25% and the magnitude > 23. We find that the GINI coefficient is the most stable in terms of AGN and magnitude/redshift, followed by the moment of light (M20), Conselice–Bershady (CCON), and finally the Abraham (CABR) concentration indexes. We find that, when using morphological parameters, the combination of CABR, CCON, and asymmetry is the most effective in classifying active galaxies at high-redshift, followed by a combination of CABR and GINI. Full article

Retinal degeneration is associated with dietary factors and environmental light exposure. This study investigated the effects of a high-fructose high-fat (HFHF) diet on susceptibility to blue light (BL)-induced retinal damage. Male ICR mice were randomized into three groups: control, BL alone, and BL plus HFHF diet (BL + HFHF). The BL + HFHF group consumed the HFHF diet for 40 weeks, followed by 8 weeks of low-intensity BL exposure (465 nm, 37.7 lux, 0.8 μW/cm²) for 6 h daily. The BL group underwent the same BL exposure while kept on a standard diet. Histopathological analysis showed that, under BL exposure, the HFHF diet significantly reduced the number of photoreceptor nuclei and the thickness of the outer nuclear layer and inner/outer segments compared to the BL group (p < 0.05). While BL exposure alone caused oxidative DNA damage, rhodopsin loss, and Müller cell activation, the combination with an HFHF diet significantly amplified the oxidative DNA damage and Müller cell activation. Moreover, the HFHF diet increased blood–retinal barrier permeability and triggered apoptosis under BL exposure. Mechanistically, the BL + HFHF group exhibited increased retinal advanced glycated end product (AGE) deposition, accompanied by the activation of the receptor for AGE (RAGE), NFκB, and the NLRP3 inflammasome-dependent IL-1β pathway. In conclusion, this study underscores that unhealthy dietary factors, particularly those high in fructose and fat, may intensify the hazard of BL and adversely impact visual health. Full article

Familial Alzheimer’s disease (FAD) caused by presenilin 1 (PSEN1) E280A induces the aberrant accumulation of intracellular Aβ (iAβ) in cholinergic-like neurons (ChLNs). How early iAβ accumulates in the development of ChLNs is still unknown. Consequently, the timing of appropriate therapeutic approaches against FAD is unclear. To determine the earliest iAβ in PSEN1 E280A ChLNs, flow cytometry and immunofluorescence microscopy were used to follow the development of menstrual mesenchymal stromal cells (MenSCs) into ChLNs (proliferation marker Ki67, cluster of differentiation 73 (CD73), neuronal nuclei (NeuN) marker, choline acetyl transferase (ChAT)), the kinetics of iAβ accumulation, and the simultaneous evaluation of other associated markers (e.g., DJ-1C106-SO₃; lysosomes; phosphatidylethanolamine-conjugated microtubule-associated protein 1A/1B light chain 3, LC3-II; cleaved caspase 3 (CC3)) at 0, 1, 3, 5, and 7 days. To reverse the PSEN1 E280A phenotype, we used rapamycin (RAP), verubecestat (VER), compound E (CE), epigallocatechin-3-gallate (EGCG), and tramiprosate (TM) in WT and mutant ChLNs. We found that PSEN1 E280A did not induce significant differences in the NeuN marker and ChAT in MenSCs transitioning to ChLNs. The iAβ accumulates at the earliest cholinergic developmental stage from day 0 (18%, at MenSCs stage) to day 7 (46%, at ChLNs stage), i.e., iAβ increased +156% in mutant compared to WT cells (1–6%). A significant increase in DJ-1C106-SO₃ occurs only at day 7 (+250%). While neither CC3 (0–1%) nor lysosomes were different between WT and mutant cells at any time point, a stepwise increase in autophagosome accumulation was observed from day 3 (15%) to day 7 (79%), i.e., +427%, in mutant cells. While neither RAP, VER, nor CE was able to completely reduce all PSEN1 E280A-induced markers in ChLNs, the combination of EGCG and TM was more effective in removing these markers than EGCG and TM alone in PSEN1 E280A ChLNs. Given that this investigation is based on a single menstrual blood sample from WT and PSEN1 E280A, our results should be considered exploratory. Larger sample sizes are needed. Full article