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Not so typical doubly eclipsing systems
No full textClassical doubly eclipsing systems are stars for which two distinct eclipsing periods that apparently come from one point source are detected. Through thorough analysis, the physical parameters of the component stars of these systems can be revealed, and sometimes even the mutual motion of the two doubles around a common barycentre can be constrained. This is most typically done via study of the eclipse-timing variations for both pairs, whose behaviour should be opposite in manner to each other, as the two doubles revolve around a common barycentre. In this study, we present rather unusual systems for which such an easy approach does not work. The period changes are clearly detectable, but only for one pair. These unusual systems are V736 And (periods 0.3596 days and 0.3069 days); ASAS J074939-3037.0 (0.4417 d, 0.2648 d); OGLE BLG-ECL-123507 (1.0170 d, 2.9488 d); ASASSN-V J180818.54-684329.4 (0.3392 d, 3.3234 d); and CRTS J191726.4-543540 (0.3129 d, 2.8178 d). Several hypotheses are presented regarding the possible origins of such behaviour. However, a final decisive explanation is still yet to be determined
An analysis of the JAGB method from the perspective of the asymptotic giant branch evolution
No full textThe JAGB method has been proposed over the last years as a possible distance indicator for the galaxies in the Local Group and possibly beyond. The nature of the stars populating the J region, as well as the conditions of the star formation history and the structural properties of the galaxies for the straight application of this method, still need to be investigated.
We studied the populations of the J region of the colour-magnitude rm (J-K,J) plane of the Large and Small Magellanic Clouds (LMC and SMC, respectively) to relate the shape of the J luminosity function (JLF) to the details of the formation histories of the two galaxies. Our aim is to try and distinguish the general aspects of the JLF to those more sensitive to the stellar population of the specific galaxy considered.
We used a population synthesis approach, based on the combined results from stellar evolution and dust formation modelling, to find the expected distribution of the stars within the J region. We then compared the outcome with results derived from observations of LMC and SMC stars. Some physical assumptions, mostly related to the modelling of the red giant branch (RGB) and asymptotic giant branch (AGB) phases of stars, were tuned until a satisfactory agreement between the expectations from synthetic modelling and the observational evidence was reached.
The sources observed within the J region were characterised as stars that recently reached the C-star stage and have not yet accumulated the extremely large amounts of carbon required to make the evolutionary track to evolve off the J region. Generally speaking, ̊m 2-3 M_⊙ stars stay within the J region longer, while lower mass objects evolve there for at most a couple of inter-pulse phases. The analysis of the JLF of the LMC, peaking at the J magnitudes expected for these stars, confirms this understanding. In the SMC, the distribution of the J fluxes is shifted to higher J magnitudes when compared to the LMC, which we interpret as the signature of a generally older population, with lower mass progenitors
The hybrid Nova Vul 2024 (=V615 Vul)
No full textAmong galactic novae, many remain poorly characterized due to heterogeneous data, observational challenges, or heavy reddening along the Galactic plane. A detailed characterization is particularly crucial for novae exhibiting peculiar features, such as those belonging to the hybrid class.
We present the spectroscopic and photometric evolution of the heavily reddened Nova Vul 2024 (=V615 Vul) from discovery on 29 July 2024 to well into its nebular phase.
We obtained daily optical, absolute-fluxed spectroscopy in both low- and high-resolution echelle modes, providing a detailed account of the spectral evolution. Photometric data were primarily sourced from AAVSO, while refined astrometry was performed to assess the positional coincidence with a potential progenitor. Robust determinations of t_3 and E_B-V were achieved, allowing for the application of the Maximum Magnitude–Rate of Decline (MMRD) relation; the resulting distance is in excellent agreement with 3D Galactic extinction maps.
Nova Vul 2024 is a very fast nova (t_3=10.7±0.5 d) located at a distance of 5.0±1.0 kpc, suffering from a large reddening (E_B-V =1.6±0.1). Around maximum light, it exhibited a Fe II-type -1 ) and high-velocity P-Cygni absorptions. Following t_3, coinciding with the emergence of hard X-ray emission, the nova displayed pronounced photometric oscillations primarily driven by continuum variations. Simultaneously, He/N features developed alongside Fe II lines, classifying V615 Vul as a rare hybrid nova. During the nebular phase, the ionization level increased, reaching Fe VII and likely Fe X . The ejecta showed no neon overabundance and expanded ballistically, as indicated by the constant widths, profiles, and castellation of the high-resolution emission lines
VAR-PZ : Constraining the photometric redshifts of quasars using variability
No full textThe Vera C. Rubin Observatory's Legacy Survey of Space and Time (LSST) is expected to obtain observations of over ten million quasars. The survey's exceptional cadence and sensitivity will enable a significant fraction of these objects to be monitored in the ugrizy bands, spanning observed wavelengths of approximately 0.3-1.0,μ ) based on the redshift, the rest-frame wavelength, and the AGN luminosity. We constructed variability-based photometric redshift (photo-z) priors by modeling the observed variability using the expected DRW parameters at a given redshift. These variability-based photo-z ( ) priors were then combined with traditional spectral energy distribution (SED) fitting to improve the redshift estimates from SED fitting. Validation was performed using observational data from the Sloan Digital Sky Survey (SDSS), demonstrating significant reduction in catastrophic outliers by more than 10% in comparison with SED fitting techniques and improvements in redshift precision. The simulated light curves with both SDSS and LSST-like cadences and baselines confirm that will be able to constrain the photometric redshifts of SDSS-like AGNs by bringing the outlier fractions down to below 15% from 32% (SED alone) at the end of the survey. The unprecedented number of sources makes spectroscopic follow-up for the vast majority of them unfeasible in the near future, so most studies will have to rely on photometric redshift estimates which are traditionally much less reliable for Active Galactic Nuclei (AGNs) than for inactive galaxies. This work presents a novel methodology to constrain the photometric redshift of AGNs that leverages the effects of cosmological time dilation, and of the luminosity and wavelength dependence of AGN variability. Specifically, we assume that the variability can be modeled as a damped random walk (DRW) process, and we adopted a parametric model to characterize the DRW timescale (τ) and asymptotic amplitude of the variability (SF _∞ VAR-PZ VAR-P
Analysis of eleventh-grade students’ scientific literacy based on PISA-framework in reaction rate topic
No full textMapping domain-level scientific literacy can guide instruction on specific chemistry topics. Objective: To profile eleventh-graders’ scientific literacy on reaction rate using the PISA 2015 science framework (context, scientific competencies, scientific knowledge). Methods: Cross-sectional descriptive survey with N = 102 students (three intact classes). A 35-item multiple-choice test was developed; 25 items that met the point-biserial validity criterion (≥ 0.30) and yielded α = 0.87 were retained in the final instrument. Scores (total and domains) were expressed as percent-correct; analyses were descriptive only (mean, SD, median, IQR, range). Results: Overall score reached M = 75.29%, SD = 20.65, median 84%, IQR 57–96%, range 24–100%. Domain means were 75.17% for context, 76.12% for scientific competencies, and 73.47% for scientific knowledge. Conclusion: Findings indicate mid-to-high performance with a relatively balanced domain profile and scope to strengthen scientific knowledge. These percentages are not directly comparable to PISA ability-scale scores (different metric and coverage); results are intended for internal mapping to inform improvement in reaction-rate instruction
Primer Design for Amplification of Lignin Peroxidase H8 (lipH8) from Phanerochaete chrysosporium using Ugene Software as an Effort to Accelerate Lignocellulose-based Bioenergy Production Technology
No full textLigninase enzymes play a crucial role in the delignification stage of lignocellulose-based bioenergy production, especially in bioethanol production, providing an environmentally friendly and cost-efficient process with minimal byproducts. However, the practical application of this strategy is limited by the low expression level of wild-type ligninase from Phanerochaete chrysosporium. Heterologous protein expression provides a promising solution to overcome this limitation. Primer design is a key step in recombinant DNA assembly for successful heterologous expression. Using bioinformatic tool, in silico primer design enables pre-laboratory optimization to enhance experimental success rate. This study aimed to design primers for the lipH8 gene from Phanerochaete chrysosporium through sequence homology analysis using the Ugene software. Lignin peroxidase isozyme H8 (lipH8) showed the highest catalytic activity in lignin degradation among the ligninase family. Primer selection was based on amplification size, self-dimer formation, and open reading frame consideration. The optimal primer pair identified was a 20-base pair forward primer (‘5-GCATGGTGGGGTGAAATACG-‘3) and reverse primer (‘5-TGTGAGACGAGTCGGTGATG-‘3), predicted to amplify a 1630 bp fragment of lipH8. This primer pair showed no self-dimer formation and exhibited superior open reading frame coverage compared to other candidates, making it suitable for further experimental validation in heterologous expression system
Recent achievements of Industrial Symbiosis in the steel sector based on the Symbio-Steel project: a review
No full textIndustrial Symbiosis refers to a collaborative approach, including synergies among companies for the transaction of resources, such as materials, energy, water, and by-products, thus resulting in mutual benefits and promoting a Circular Economy approach. Over the past decades, the steel sector was committed to reduce waste production as well as reuse waste and by-products to exploit them as a resource. Significant results in Industrial Symbiosis implementation have been achieved, creating new synergies and networks with other industrial sectors. Nonetheless, a comprehensive analysis of technical and non-technical barriers, that hinder the successful implementation of Industrial Symbiosis within the steel sector, can help implement an integrated and synergic approach encompassing and merging results and experience already achieved. This review paper presents a comprehensive overview of recent studies on the research trends on Industrial Symbiosis, considering drivers and barriers to its implementation, and maps the recent achievements related to the steel sector, by analysing the impact of some significant case studies. For instance, CO2 valorisation in flue gases and steel slags to produce silicates and carbonates via mineral carbonation and CO2 capture, re-use and sequestration by industrial symbiosis activities involving the steel and ammonia/urea industries are presented. The literature review based on selected publications allowed tracing the evolution of Industrial Symbiosis over the last few years. The assessment of main lines for research in Industrial Symbiosis allows identifying the challenges for future research. The analysis of implementation of new technologies can help to create new symbiotic networks and further developments and scenarios for the steel industry in a future characterized by material scarcity, decarbonization, and more stringent environmental legislation
Méthodes de neuromodulation appliquées au trouble de l’usage du tabac
No full textLe tabagisme constitue un enjeu majeur de santé publique. Diverses techniques de neuromodulation offrent, désormais, de nouvelles perspectives dans la prise en charge de ce trouble. La stimulation magnétique transcrânienne, en modulant l’activité du cortex préfrontal, réduit les envies irrépressibles de fumer (craving) et la consommation de tabac, avec une bonne tolérance mais, souvent, les effets s’estompent avec le temps. La stimulation transcrânienne à courant continu donne des résultats variables selon le nombre de séances suivies, la motivation du patient et l’association avec d’autres approches thérapeutiques. Le neurofeedback, basé sur l’imagerie par résonance magnétique ou l’électroencéphalographie, permet une modulation volontaire de l’activité cérébrale, avec des résultats prometteurs mais encore limités
Cooperative dynamics of EEG rhythms in adolescents with traumatic brain injuries
No full textAnalysis of dominant rhythms of the brain’s electrical activity and individual paired brainwave interactions provides limited information about physiological states and functions, in contrast to a more general approach that considers the coordination of all significant cortical rhythms within a complex network. This approach, without refuting traditional neurophysiological concepts, provides more comprehensive details about the coordinated dynamics of rhythmic processes, thereby improving diagnostic capabilities. Using the concept of cross-communication of physiologically significant cortical rhythms, in this study, we examine the characteristics of brainwave coordination in adolescents with traumatic brain injury (TBI) at different stages of the sleep-wake cycle. Using a simplified analysis method focusing on the behavior of average values of the relative spectral power, we note significant differences between the coordinated behavior of brain waves in adolescents with TBI and healthy individuals of the same age. These differences are observed in wakefulness and become insignificant during deep sleep, which may contribute to the therapeutic effect of sleep in traumatic brain injuries
