16918 research outputs found
Sort by
Model-agnostic assessment of dark energy after DESI DR1 BAO
No full textBaryon acoustic oscillation measurements by the Dark Energy Spectroscopic Instrument (Data Release 1) have revealed exciting results that show evidence for dynamical dark energy at ∼ 3σ when combined with cosmic microwave background and type Ia supernova observations. These measurements are based on the w 0 w a CDM model of dark energy. The evidence is less in other dark energy models such as the wCDM model. In order to avoid imposing a dark energy model, we reconstruct the distance measures and the equation of the state of dark energy independent of any dark energy model and driven only by observational data. Our results show that the model-agnostic (in terms of late-time models) evidence for dynamical dark energy from DESI is not significant. Our analysis also provides model-independent constraints on cosmological parameters such as the Hubble constant and the matter-energy density parameter at present. Although we used CMB distance priors (not full CMB data) from a ΛCDM early-time model, our results remain largely similar for other cosmological models, provided that these models do not differ significantly from the standard model
Physical versus phantom dark energy after DESI: thawing quintessence in a curved background
No full textRecent data from Dark Energy Spectroscopic Instrument, in combination with other data, provide moderate evidence of dynamical dark energy, w = −1. In the w 0 , w a parametrization of w, there is a preference for a phantom crossing, w < −1, at redshift z ∼ 0 . 5. In general relativity, the phantom equation of state is unphysical. Thus, it is important to check whether phantom crossing is present in other physically self-consistent models of dark energy that have equi v alent e vidence to the w 0 , w a parametrization. We find that thawing quintessence with non-zero cosmic curvature can fit the recent data as well as w 0 , w a in a flat background, based on both parametric and realistic scalar field evolutions. Although the realistic model does not allow w < −1, the parametrizations do allow it. However even if we allow w < −1 the data do not enforce phantom crossing. Thus, the phantom crossing is an artefact of a parametrization that is not based on a physical model
Searching for Axion Dark Matter Gegenschein of the Vela Supernova remnant with FAST
No full textAxions are one of the leading dark matter candidates. If we are embedded in a Milky Way dark matter halo comprised of axions, their stimulated decay would enable us to observe a counterimage (“axion gegenschein”) with a frequency equal to half the axion mass in the opposite direction of a bright radio source. This spectral line emission will be broadened to Δν/ν ∼ σd/c ∼ 10−3 due to the velocity dispersion of dark matter, σd. In this pilot study, we perform the first search for the expected axion gegenschein image of Vela supernova remnant with
26.4 hr of effective ON–OFF data from the Five-hundred-meter Aperture Spherical radio Telescope (FAST) Lband (1.0–1.5 GHz) 19 beam receiver. Our null detection limits the axion–photon coupling strength to be gaγγ ≲ 2 × 10−10 GeV−1 in the mass ranges of 8.7 μeV � ma � 9.44 μeV and 10.85 μeV � ma � 12.01 μeV. These results provide a stronger constraint on gaγγ in this axion mass range than the current limits obtained by the direct search of an axion decay signal from a dwarf galaxy that uses FAST observations, but are a factor of ∼3 times weaker than the current CERN Axion Solar Telescope limit. Based on our observation strategy, data processing methods, and results, the expected sensitivity will reach ∼10−11 GeV−1 with ∼2000 hr of observation in the future
Protective effects of Aspalathus linearis against oxidative stress in human spermatozoa: Comparison with ascorbic acid
No full textAspalathus linearis extracts protect human spermatozoa from oxidative stress in vitro. Rooibos extracts reduce oxidation-reduction potential induced by cumene hydroperoxide. Rooibos shows comparable or superior antioxidant effects to ascorbic acid. Treatment preserves sperm motility, viability, mitochondrial function, and DNA integrity. Oxidative stress is a major contributor to male infertility due to its detrimental effects on sperm function. This study determined the antioxidant potential of fermented and unfermented rooibos extracts compared to ascorbic acid in protecting human spermatozoa from oxidative damage induced by cumene hydroperoxide. Semen samples from 25 healthy donors were processed and exposed to 100 µM cumene hydroperoxide, with treatment groups receiving varying concentrations of rooibos extracts or ascorbic acid. Sperm parameters, including motility, viability, mitochondrial membrane potential, DNA fragmentation, reactive oxygen species, capacitation, and acrosome reaction, were assessed after 60 and 120 minutes. Human tubular fluid supplemented with bovine serum albumin was used as a negative control, while cumene hydroperoxide alone served as the positive control. Both rooibos extracts and ascorbic acid significantly reduced oxidative stress, measured by static oxidation-reduction potential, compared to the positive control (p < 0.0001). Treatment improved sperm motility, viability, mitochondrial function, capacitation, and acrosome reaction, while decreasing DNA fragmentation and reactive oxygen species levels (p < 0.05). Rooibos exhibited antioxidant effects comparable to ascorbic acid. Aspalathus linearis extracts effectively protect human spermatozoa against oxidative damage and preserve essential functional parameters, supporting their potential use as natural antioxidants in male fertility management
Effect of 2,2-Dialkyl/Diaryl substituents on the opto-electronics of poly (propylene-3,4-ethylenedioxythiophenoimine)-co-poly(3,4- propylenedioxythiophene) dendritic star copolymers
No full textA series of four dendritic star copolymers that consist of G2poly(propyleneamine) dendrimer core, and pendants of poly(propylene-3,4-ethylenedioxythiophene) substituted with 2,2- dibenzyl, 2,2-dicyclohexylmethyl, 2,2-dimethyl, and 2,2-dihexyl that grew out from the core, were synthesized using a combination of Schiff base condensation and chemical oxidative copolymerization techniques. Chemical structures of dendritic star copolymers were examined and confirmed using nuclear magnetic resonance (NMR), Raman, and Fourier transform infrared spectroscopies (FTIR). The effect of the 2,2-dialkyl substituents on the opto- electronics and thermal stability of the dendritic star copolymers was evaluated using ultraviolet-visible spectroscopy (UV–Vis), thermogravimetric analysis (TGA), and photoluminescence (PL). Insertion of long chains of 2,2-dicyclohexyl showed a bathochromic shift and reduction in optical band gap compared to other substituents. TGA revealed less thermal resistance and fast degradation rates at temperatures above 300 °C associated with copolymers decomposition. This work revealed that modification of copolymers with alkyl or aryl substituents alter significantly with their thermal and optical properties by changing the decomposition temperature and optical bandgap
The relationship between intolerance of uncertainty and alcohol use in first responders: the direct, indirect and moderating role of generalized resistance resources
No full textRaw data for investigating the relationship between intolerance of uncertainty and alcohol use, and the role of resilience, jardiness, self-efficacy and self-compassion
Assessing orthodontic treatment outcome of patients treated by orthodontic registrars - using the Peer Assessment Rating index
No full textBackground: Orthodontic treatment aims to improve occlusion and aesthetics in patients’ dentition. Assessing the degree of improvement is important to establish the standard of care provided by an individual orthodontist or a tertiary care institution. This study aimed to assess the orthodontic treatment outcomes of patients designated for use in final examinations by registrars in the postgraduate orthodontics program at the University of the Western Cape (UWC). The assessment was performed using the Peer Assessment Rating (PAR) index. Additional outcome measures included extraction, non-extraction, orthodontic prescription, impactions, Angle classification, and duration of treatment. Orthodontic study models and treatment records of patients who met the inclusion criteria were included. The final sample consisted of seventy-five patients with a mean age of 16 years and 6 months and a sex distribution of 47 (63%) females and 28 (37%) males. The PAR index was used to assess the pre- (T0) and post-treatment (T1) orthodontic study models. Additional outcome measures were assessed using the treatment records of the study sample
Genome-wide characterization of DREB transcription factors in Medicago truncatula: Insights into their roles in development and abiotic stress response
No full textDehydration-responsive-element binding (DREB) proteins play a crucial role in drought, salt, and environmental stress tolerance. In this study, we identified and annotated fifty-four DREB genes from the Medicago truncatula genome. These genes were analyzed at the molecular level, focusing on gene classification, genomic organization, phylogeny, synteny, structural features, and expression profiles. Phylogenetic analysis revealed that MtDREB proteins are categorized into six subgroups (A1–A6), with highly conserved motif compositions among them. Expression profiling showed that MtDREB genes are differentially expressed in various plant organs and under abiotic stresses (cold, salinity, and dehydration), with 30 % exhibiting high expression during flowering and development. Data from RNA-seq and microarrays demonstrated that 76 % of MtDREB genes are differentially expressed under at least one stress condition, indicating their involvement in various signaling pathways activated by abiotic stresses. Notably, MtDREB05, primarily induced under osmotic stress, appears to be a promising candidate for improving abiotic stress tolerance. These findings will enhance our understanding of the DREB family and aid in functional validation of DREBgenes in M. truncatula and related forage species
BRAF p.V600E-negative langerhans cell histiocytosis associated with a periapical cyst: a case presentation with broad review of the differential diagnosis and disease pathophysiology
No full textBackground: Langerhans cell histiocytosis (LCH) rarely presents in the oral and maxillofacial region, and while isolated and small collections of Langerhans-type cells have been found in periapical cysts, there have been no reported cases of LCH arising in periapical cysts. Methods: A 58-year-old female presented with isolated erythematous dry skin lesions and a radiolucent lesion of the anterior maxilla. Microscopic examination of the enucleation specimen revealed a periapical cyst with large collections of atypical cells with grooved folded nuclei with eosinophils consistent with LCH. Immunohistochemistry (IHC) was performed to confirm the diagnosis. BRAF mutation status was evaluated with the BRAF p. V600E antibody and the automated real-time PCR-based Idylla™ assay, capable of qualitative detection of 5 mutations in codon 600 of the BRAF gene. Results: The LCH cells were positive for S100, CD1a, and Langerin (CD 207) and negative for BRAF p. V600E mutations. Ki-67 was 45%. Conclusion: The association of LCH with a periapical cyst could be explained by the active surveillance and migration of neoplastic Langerhans-type cells in blood to the site of apical chronic inflammation, in a patient with LCH. Careful attention to morphologic features in conjunction with Langerin IHC, helps exclude other closely-related dendritic tumours. BRAF p. V600E testing, ideally with real-time PCR assays, can help identify patients who may benefit from BRAF inhibitor therapies. New generations of sequencing that cover a large panel of genetic alterations beyond the frequent BRAF p. V600E mutations (e.g. rare in-frame BRAF deletions), could provide valuable information about the extent, prognosis and treatment of LCH patients. © The Author(s) 2025
Immunomodulatory nanoparticles induce autophagy in macrophages and reduce mycobacterium tuberculosis burden in the lungs of mice
No full textTuberculosis (TB) is the leading cause of death frominfectious disease. Macrophages are the primary immune respondersand become the primary host cells for the causative agentMycobacterium tuberculosis. Following the uptake of M. tuberculosis,the inherent antimicrobial action of macrophages is dampened,enabling the bacterium to reside within these cells and multiply.Rising resistance of M. tuberculosis to antibiotics has led to theinvestigation of novel approaches for the treatment of TB. Here, wereport a host-directed approach, employing biomimetic Curdlanpoly(lactic-co-glycolic acid) (C-PLGA) nanoparticles (NPs), andexamine autophagy induction in infected macrophages, eradication ofM. tuberculosis and immune modulation in a mouse model. Wedemonstrate that the NPs induce autophagy in M. tuberculosis-infectedmacrophages. Treatment of H37Rv infected C57BL/6 mice with these NPs reduced M. tuberculosis burden in the lungs of mice andmodulated cytokines and chemokines and this work demonstrates that these immunomodulatory NPs are a potential treatmentapproach for T