Recent publications
- T. Sivarani
- Smitha Subramanian
- Avrajit Bandyopadhyay
- [...]
- Bharat Kumar Yerra
This article addresses key open questions in the Milky Way and neighboring galaxies, focusing on utilizing stars and stellar populations to trace galaxy formation and evolution processes. It offers an overview of the current landscape based on community-contributed white papers and outlines emerging research avenues alongside specific observational strategies relevant to the Indian context. Recent advancements in observations, such as precision astrometry from Gaia and asteroseismology enabled by Kepler, have reinvigorated interest in stellar physics, including its role in characterizing exoplanet atmospheres and understanding planet formation and evolution. Upcoming projects like the Rubin Observatory (LSST) and future large spectroscopic surveys will significantly enhance our ability to study stellar populations across various galaxies. These efforts will improve our understanding of dark matter distribution in galaxies, galaxy formation, and their evolution. Furthermore, by studying galaxies within the local volume, researchers can delve into the history of the formation of low-mass dwarf galaxies, the most common type of galaxy in the Universe. The local volume presents an excellent opportunity to test theories of hierarchical galaxy formation and assembly, especially since high-redshift observations of these galaxies’ formation epochs are beyond the reach of current telescopes. Therefore, this article seeks to summarize the current understanding and chart a path forward for the field.
- Carolina Arbeláez
- Giovanna Cottin
- Juan Carlos Helo
- [...]
- Téssio B. de Melo
A bstract
Neutrino masses and dark matter (DM) might have a common origin. The scotogenic model can be considered the proto-type model realizing this idea, but many other variants exist. In this paper we explore the phenomemology of a particular DM neutrino mass model, containing a triplet scalar. We calculate the relic density and check for constraints from direct detection experiments. The parameter space of the model, allowed by these constraints, contains typically a long-lived or quasi-stable doubly charged scalar, that can be searched for at the LHC. We reinterpret existing searches to derive limits on the masses of the scalars of the model and estimate future sensitivities in the high-luminosity phase of the LHC. The searches we discuss can serve to constrain also many other 1-loop neutrino mass models.
Various phenomenological generalizations of the foundational equation in quantum physics have been proposed in prior studies. This paper presents a rigorous analytical derivation, grounded in first principles, that elucidates the impact of quantum fluctuations on the evolution of quantum systems. Furthermore, it demonstrates how this essential generalization can be achieved through statistical methods. The paper reveals that standard linear equations of quantum mechanics are recovered under specific limits of the parameter that governs nonlinear behavior. It establishes a direct correlation between the decay of quantum waves and the magnitude of these fluctuations. This connection provides critical insights into the dynamic properties of quantum systems and their susceptibility to underlying stochastic influences. Moreover, this work successfully formulates a comprehensive approach to a complete family of nonlinear quantum evolution equations. This framework expands our theoretical arsenal and enhances our ability to model and predict the behavior of complex quantum systems under various conditions. This research represents a significant advancement in our understanding of quantum mechanics, offering a more nuanced view of how quantum systems evolve under the influence of intrinsic fluctuations. It paves the way for future explorations into the stability, coherence, and dynamical evolution of quantum states, potentially impacting quantum computing, information processing, and other applications in quantum technology.
The seed layer-assisted synthesis of ZnO nanotubes has emerged as an efficient method to significantly enhance the structural and electronic characteristics of ZnO nanomaterials. By employing a carefully prepared seed layer, this technique facilitates the nucleation process, leading to the controlled growth of ZnO nanotubes with well-defined morphologies. Such precision in morphology is critical, as it directly influences the material’s functional properties. In this study, ZnO nanotubes with an average diameter of approximately 250 nm and a surface density of 22–25 nanotubes/µm2 were achieved following four cycles of coating. This layered approach allowed for consistent nanotube formation, enabling us to obtain a densely packed array of nanotubes with uniform structural characteristics across the substrate. Energy-dispersive X-ray (EDX) analysis and X-ray diffraction (XRD) measurements confirmed the formation of ZnO nanotubes with an average crystal size of 40.8 nm. XRD results indicated a preferential growth orientation along the (002) crystallographic plane, suggesting a highly oriented structure conducive to enhanced electronic performance. Further insights were gained from Mott Schottky and optical absorbance analyses, which revealed the n-type semiconducting behavior of the ZnO nanotubes and an optical bandgap of approximately 3.28 eV. In summary, this study demonstrates that the seed layer-assisted approach is a viable strategy to produce ZnO nanotubes with tailored properties, showcasing potential for applications in fields ranging from nanoelectronics to biosensors. The observed control over structural parameters and electronic characteristics highlights this synthesis technique as a valuable tool in the development of next-generation nanomaterials with specific functionality tailored to diverse technological applications.
The Azores Archipelago, prone to multiple geohazards such as earthquakes, volcanic eruptions, and extreme weather events, faces significant risks of landslides, particularly due to the complex geological characteristics of its volcanic formations. This study focuses on assessing the seismic stability of a slope near Porto Formoso on São Miguel Island, composed of trachytic volcanic rock overlain by a loose pumice deposit. Using the Volcanic Rock Stability (VRS) empirical system, tailored for volcanic rock environments, this study provides a geotechnical evaluation that considers the unique heterogeneities of these formations. The VRS system's application yielded classifications ranging from Class III (Reasonable) to Class IV (Regular), reflecting varying degrees of stability under seismic conditions. A 3D numerical model, using the Material Point Method (MPM), was developed to simulate the slope's behavior under seismic loading as defined by Portuguese regulations. The analysis identified a Factor of Safety (FS) of 3.85, indicating stability under the specified conditions but highlighted potential risks under more extreme seismic events. A run-out analysis further indicated that slope failure could result in significant material deposition, potentially obstructing critical access routes and posing risks to local infrastructure. These results underscore the need for targeted mitigation strategies to enhance the resilience of volcanic slopes in seismic-prone regions.
Water utilities provide water and sanitation services in monopolistic conditions. Hence, assessing their performance through benchmarking is crucial for proper regulation. This research addresses the limitations of self-evaluation Data Envelopment Analysis (DEA) models commonly used for benchmarking water utilities’ efficiency. Given that these models often lead to overestimated efficiency scores, our study introduces a cross-efficiency analysis framework integrating both self and peer-evaluation perspectives. This innovative approach, applied to a representative sample of Chilean water utilities, uniquely considers unplanned water supply interruptions and sewerage blockages as undesirable outputs, emphasizing service continuity. Average techno-economic efficiency scores based on self-evaluation, and peer-evaluation were 0.681 and 0.388, respectively. Hence, significant techno-economic efficiency overestimations in self-evaluation scores are evident, with implications for regulatory challenges and potential service quality compromises. The data also highlights a considerable opportunity for improvement in water and sanitation continuity in Chilean water utilities. The findings not only shine a spotlight on the inherent biases of prevalent benchmarking techniques but also highlight a substantial avenue for bolstering water and sanitation service continuity within water utilities.
Processed food products (PFPs) are amply consumed and important sources of nutrients worldwide. Evaluating PFPs by their composition fails to recognize that nutrients are embedded in food matrices and processing modifies their nutritional functionality, for example, the bioaccessibility and bioavailability. PFPs with equivalent chemical composition may experience the “food matrix effect”: a difference in the nutritional outcome and health potential. This review presents food matrices attained after processing and their nutritional significance. It also delves into the complex kinetics of digestion conducive to nutrient release from matrices and nutrient interactions before absorption in the small intestine, and the role of microbial fermentation in the colon. Matrices of PFPs can be designed or redesigned and manufactured to be tasty, nutritious, sustainable, as special foods for vulnerable groups, innovative products from novel food sources, and to feed a healthy microbiota. The potential for nutritional improvement of PFPs is driven by understanding the food materials science and changes in food matrices during processing, control of formulation and manufacturing variables, the application of novel technologies, and a multifactor toolbox that supports the rational design of healthy food matrices.
Bonamia (Haplosporida) are oyster parasites capable of devastating oyster populations. The near-circumglobal distribution of the host generalist B. exitiosa has previously been associated with the natural and anthropogenic dispersal of broadly distributed non-commercial oysters in the Ostrea stentina species complex. Here, we took a global snapshot approach to explore the role of the widely introduced Pacific oyster Magallana gigas , a commercially important species that can be found on every continent except Antarctica, in transporting Bonamia. We screened 938 M. gigas individuals from 41 populations in this oyster’s native and non-native geographic range for presence of Bonamia DNA using PCR. B. exitiosa was the only species detected and only within 2 of 5 populations from southern California, USA (10 and 42% PCR prevalence). Therefore, M. gigas could have played a role in transporting B. exitiosa to California (if introduced) and/or maintaining B. exitiosa populations within California, but morphological confirmation of infection needs to be done to better understand the host-parasite dynamics within this system. We detected no Bonamia DNA within any other non-native M. gigas populations (n = 302) nor within native M. gigas populations in Japan and Korea (n = 582) and thus found no evidence to support the co-dispersal of M. gigas and other Bonamia species. Lower sample sizes within some populations and the non-systematic nature of our sampling design may have led to false negatives, especially in areas where Bonamia are known to occur. Nevertheless, this global snapshot provides preliminary guidance for managing both natural and farmed oyster populations.
Niemann-Pick disease (NP) is a group of rare genetic disorders that affect normal lipid metabolism and cause an accumulation of lipids in the liver, spleen, brain, and bone marrow. NP patients develop brain alterations and a very fast progression of liver damage. The purpose of this study is to characterize the changes in liver lipid composition during the progression of this disease using ex vivo magnetic resonance spectroscopy (MRS) in mouse models with the aim of identifying potential biomarkers to support a future non-invasive technique to follow-up these patients. NP type C (NPC) and wild-type (WT) mice were fed a chow diet and euthanized at 5 weeks of age (n = 5 per group) and 9 weeks of age (n = 5 per group). We extracted lipids from their livers and analyzed them with Gas Chromatography-Mass Spectrometry (GC-MS) and MRS. With the GC-MS analysis, 7 main fatty acids (FA) and cholesterols were quantified. Using MRS, we identified 5 metabolite peaks that correspond to FA only, 3 peaks that correspond to cholesterol only, and 2 peaks that correspond to FA and cholesterol. Our results show that the increase in liver cholesterol is the key biomarker for liver damage in NPC, which is consistent with a bad liver disease prognosis due to the association of increased cholesterol levels and liver inflammation. Additionally, we identified a difference in the pool of FA stored in the NPC compared to the WT mouse livers. Those different liver spectra could provide potential biomarkers for the non-invasive follow-up of NPC patients.
The molecular confinement within rigid macrocyclic receptors can trigger catalytic activity and steer the selectivity of organic reactions. In this work, the dimerization of methylcyclopentadiene (MCPD) isomers in the presence of cucurbit[7]uril (CB7) was found to display, besides a large rate acceleration, a striking regioselectivity in aqueous solution at pH 3, different from the products predominating in the absence of the supramolecular catalyst. Among the different possible regioisomers and diastereomers, the endo‐3,7‐dimethyl‐3a,4,7,7a‐tetrahydro‐1H‐4,7‐methanoindene adduct was selectively formed, which is otherwise found only as a minor product in the dimerization of neat MCPD or in commercial dimeric mixtures. This product originates from the reaction of the heteroternary complex of 1‐MCPD and 2‐MCPD within CB7, in which the methyl groups are positioned in an “anti‐diaxial” arrangement and point towards the open portals of the macrocycle, resulting in a preferred packing of the reacting cyclopentadiene rings. The selectivity of the dimerization of MCPD in the absence and presence of CB7 is supported by quantum‐chemical calculations.
This paper presents new evidence on schooling mobility across three generations in six Latin American countries. By combining survey information with national census data, we have constructed a novel dataset that includes 50,000 triads of grandparents, parents, and children born between 1890 and 1990. We estimate five intergenerational mobility measures, finding that multigenerational persistence in our six countries is twice as high as in developed countries, and 77% higher than iterating a two-generation model would predict. A theory of high and sticky persistence provides a better approximation for describing mobility across multiple generations in our sample. Even with high persistence, we uncover significant mobility improvements at the bottom of the distribution by estimating measures of absolute upward mobility and bottom-half mobility over three generations. This novel evidence deepens our understanding of long-term mobility, and we expect future research to replicate it as more multigenerational data becomes available in different contexts.
This study examines how pre-service science teachers integrate technology into the design of learning activities, paying particular attention to types of technology integration, cognitive demand, scientific research skills, and TPACK. A mixed methods approach was used to analyze 49 learning activities designed by pre-service physics, chemistry, and biology teachers. The results of this study demonstrate that most pre-service science teachers preferred content-specific technologies for their science classrooms. A notable trend among physics teachers was the use of technologies that facilitate authentic scientific practices. A significant difference was observed between high cognitive demand activities associated with content-specific technologies and low cognitive demand activities linked to technologies unrelated to science. Another important finding suggests that specific technologies contribute to improving students’ scientific research skills. Furthermore, teacher TPACK knowledge, determined through performance assessments, was correlated with the integration of content-specific technologies. Finally, discussions and recommendations for science teacher preparation and research on science education using technology are provided.
Plain Language Summary
Active upper‐plate faults in subduction zones worldwide have shown activity before, during, and after large earthquakes, suggesting a link with megathrust behavior. Advancing our understanding of these mechanisms is essential for enhancing seismic hazard assessment. The 2014 Iquique earthquake (Mw 8.2) in Northern Chile is probably the best‐documented earthquake in terms of pre‐earthquake upper‐plate activity, characterized by an intense foreshock sequence 15 days before the main event. Here, we use numerical simulations of the seismic cycle over several thousand years to analyze the interaction between crustal faulting and foreshocks preceding events like the 2014 Iquique earthquake. Upper‐plate faults in our models significantly influence the seismic activity prior to the mainshock and are key to explaining the geodetic observations of coseismic displacements. Additionally, we find that the hydraulic state at the plate interface strongly affects foreshock activity. This research highlights the importance of fault interactions and fluid dynamics in the seismic cycles of subduction zones.
Background
Capillary refill time (CRT) and skin blood flow (SBF) have been reported to be strong predictors of mortality in critically ill patients. However, the relationship between both parameters remains unclear.
Methods
We conducted a prospective observational study in a tertiary teaching hospital. All patients older than 18 years admitted in the intensive care unit (ICU) with circulatory failure and a measurable CRT were included. We assessed index SBF by laser doppler flowmetry and CRT on the fingertip, at T0 (Within the first 48 h from admission) and T1 (4 to 6 h later). Correlation was computed using Spearman or Pearson’s formula.
Results
During a 2-month period, 50 patients were included, 54% were admitted for sepsis. At baseline median CRT was 2.0 [1.1–3.9] seconds and median SBF was 46 [20–184] PU. At baseline SBF strongly correlated with CRT (R² = 0.89; p < 0.0001, curvilinear relationship), this correlation was maintained whether patients were septic or not (R² = 0.94; p = 0.0013; R² = 0.87; p < 0.0001, respectively), and whether they received norepinephrine or not (R² = 0.97; p = 0.0035; R² = 0.92; p < 0.0001, respectively). Between T0 and T1, changes in SBF also significantly correlated with changes in CRT (R² = 0.34; p < 0.0001). SBF was related to tissue perfusion parameters such as arterial lactate level (p = 0.02), whilst no correlation was found with cardiac output. In addition, only survivors significantly improved their SBF between T0 and T1. SBF was a powerful predictor of day-28 mortality as the AUROC at T0 was 85% [95% IC [76–91]] and at T1 90% [95% IC [78–100]].
Conclusion
We have shown that index CRT and SBF were correlated, providing evidence that CRT is a reliable marker of microvascular blood flow.
Trial registration Comité de protection des personnes Ouest II N° 2023-A02046-39.
Supplementary Information
The online version contains supplementary material available at 10.1186/s13054-025-05285-y.
In recent years there has been a growing body of evidence on water-assisted colonoscopy (WAC). Water exchange (WE) colonoscopy, one of the WAC techniques, has demonstrated higher intubation rate, higher adenoma detection rate (ADR), and reduced patient discomfort compared to gas insufflation colonoscopy. In our clinical practice, we have observed increased mucus production in the rectosigmoid segments during withdrawal when WAC techniques are used with water infusion compared to saline infusion. This white, opaque mucus often requires further mucosal lavage and removal, which can be time-consuming and could decrease polyp detection rates. Since low ADR is correlated with the risk of interval colorectal cancer (CRC), further attempts to improve ADR are needed. Two recent studies have explored this phenomenon. In 2020 Rahyel et al. reported higher mucus production with room-temperature water compared to saline infusion during colonoscopy insertion. In 2023 Cheng et al. randomized patients to colonoscopy with CO2 insufflation or WE colonoscopy with warm water, 25% saline or 50% saline. Mucus production was highest in the water group, followed by the 25% saline, 50% saline, and CO2 groups.
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