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Buoyant crystals halt the cooling of white dwarf stars
No full textWhite dwarfs are stellar remnants devoid of a nuclear energy source, gradually cooling over billions of years and eventually freezing into a solid state from the inside out . Recently, it was discovered that a population of freezing white dwarfs maintains a constant luminosity for a duration comparable with the age of the universe , signalling the presence of a powerful, yet unknown, energy source that inhibits the cooling. For certain core compositions, the freezing process is predicted to trigger a solid-liquid distillation mechanism, owing to the solid phase being depleted in heavy impurities . The crystals thus formed are buoyant and float up, thereby displacing heavier liquid downward and releasing gravitational energy. Here we show that distillation interrupts the cooling for billions of years and explains all the observational properties of the unusual delayed population. With a steady luminosity surpassing that of some main-sequence stars, these white dwarfs defy their conventional portrayal as dead stars. Our results highlight the existence of peculiar merger remnants and have profound implications for the use of white dwarfs in dating stellar populations . [Abstract copyright: © 2024. The Author(s), under exclusive licence to Springer Nature Limited.
A decision support system for sustainable agriculture and food loss reduction under uncertain agricultural policy frameworks
Get PDFThe EU Green Deal requires the reduction in pesticides and fertilisers in food crop production, whilst the sustainable development goals require reductions in food loss and food waste. In a complex and interacting system like the food system, these goals are difficult to coordinate. Here, we show an approach using Bayesian network modelling for decision support. Bayesian networks are important tools for modelling complex systems which may develop emergent behaviour and for providing quantitative comparisons for different candidate policies, approaches or interventions under the Integrating Decision Support System paradigm. Using lettuce as an exemplar crop, we demonstrate that expected food loss changes under different agricultural input reduction and integrated pest management combinations can be quantified to aid decision making for growers
Effects of processing conditions on the release of sodium chloride from fat crystal ‘shell’ stabilised water-in-oil emulsions
Get PDFOver the last two decades, water-in-oil fat crystal stabilised Pickering emulsions have been increasingly studied for the controllable release of encapsulated (water-soluble) species. The stability inherent to Pickering emulsions has been shown to be enhanced by sintering to form an interfacial lipid 'shell' around the droplets, which improves the retention and prolongs the delivery of the enclosed species. Using a scraped surface heat exchanger/pin stirrer setup, the present work shows that processing conditions used to produced W/O emulsions with dispersed droplets enclosed in lipid shells, have a significant impact upon the subsequent release of NaCl enclosed within them. The best performing emulsion structure produced here is reported to retain about 98% of its initial salt load over a period of 100 days. NaCl release profiles were also used to calculate the interfacial rate constants for the transferal of salt across the lipid shells. Interfacial rate constants ranged from 5.5 to 3593.2×10−3 nm2/s and were significantly (up to three orders of magnitude) lower than those reported in literature for similar systems. Analysis revealed that depending on the specific conditions employed, the processing environment can enhance or compromise lipid shell integrity. Overall, the current study offers significant direction in terms of the optimum processing requirements that are necessary to produce fat-continuous emulsion microstructures that can successfully regulate the release of NaCl, paving the way for the successful development of food formulations of controlled salt-perception
Global, regional, and national burden of disorders affecting the nervous system, 1990–2021 : a systematic analysis for the Global Burden of Disease Study 2021
Get PDFBackground
Disorders affecting the nervous system are diverse and include neurodevelopmental disorders, late-life neurodegeneration, and newly emergent conditions, such as cognitive impairment following COVID-19. Previous publications from the Global Burden of Disease, Injuries, and Risk Factor Study estimated the burden of 15 neurological conditions in 2015 and 2016, but these analyses did not include neurodevelopmental disorders, as defined by the International Classification of Diseases (ICD)-11, or a subset of cases of congenital, neonatal, and infectious conditions that cause neurological damage. Here, we estimate nervous system health loss caused by 37 unique conditions and their associated risk factors globally, regionally, and nationally from 1990 to 2021.
Methods
We estimated mortality, prevalence, years lived with disability (YLDs), years of life lost (YLLs), and disability-adjusted life-years (DALYs), with corresponding 95% uncertainty intervals (UIs), by age and sex in 204 countries and territories, from 1990 to 2021. We included morbidity and deaths due to neurological conditions, for which health loss is directly due to damage to the CNS or peripheral nervous system. We also isolated neurological health loss from conditions for which nervous system morbidity is a consequence, but not the primary feature, including a subset of congenital conditions (ie, chromosomal anomalies and congenital birth defects), neonatal conditions (ie, jaundice, preterm birth, and sepsis), infectious diseases (ie, COVID-19, cystic echinococcosis, malaria, syphilis, and Zika virus disease), and diabetic neuropathy. By conducting a sequela-level analysis of the health outcomes for these conditions, only cases where nervous system damage occurred were included, and YLDs were recalculated to isolate the non-fatal burden directly attributable to nervous system health loss. A comorbidity correction was used to calculate total prevalence of all conditions that affect the nervous system combined.
Findings
Globally, the 37 conditions affecting the nervous system were collectively ranked as the leading group cause of DALYs in 2021 (443 million, 95% UI 378–521), affecting 3·40 billion (3·20–3·62) individuals (43·1%, 40·5–45·9 of the global population); global DALY counts attributed to these conditions increased by 18·2% (8·7–26·7) between 1990 and 2021. Age-standardised rates of deaths per 100 000 people attributed to these conditions decreased from 1990 to 2021 by 33·6% (27·6–38·8), and age-standardised rates of DALYs attributed to these conditions decreased by 27·0% (21·5–32·4). Age-standardised prevalence was almost stable, with a change of 1·5% (0·7–2·4). The ten conditions with the highest age-standardised DALYs in 2021 were stroke, neonatal encephalopathy, migraine, Alzheimer's disease and other dementias, diabetic neuropathy, meningitis, epilepsy, neurological complications due to preterm birth, autism spectrum disorder, and nervous system cancer.
Interpretation
As the leading cause of overall disease burden in the world, with increasing global DALY counts, effective prevention, treatment, and rehabilitation strategies for disorders affecting the nervous system are needed
Exploring the ageing methylome in the model insect, Nasonia vitripennis
Get PDFBackground: The ageing process is a multifaceted phenomenon marked by the gradual deterioration of cellular and organismal functions, accompanied by an elevated susceptibility to diseases. The intricate interplay between genetic and environmental factors complicates research, particularly in complex mammalian models. In this context, simple invertebrate organisms have been pivotal, but the current models lack detectable DNA methylation limiting the exploration of this critical epigenetic ageing mechanism. This study introduces Nasonia vitripennis, the jewel wasp, as an innovative invertebrate model for investigating the epigenetics of ageing. Leveraging its advantages as a model organism and possessing a functional DNA methylation system, Nasonia emerges as a valuable addition to ageing research. Results: Whole-genome bisulfite sequencing unveiled dynamic alterations in DNA methylation, with differentially methylated CpGs between distinct time points in both male and female wasps. These changes were associated with numerous genes, enriching for functions related to telomere maintenance, histone methylation, and mRNA catabolic processes. Additionally, other CpGs were found to be variably methylated at each timepoint. Sex-specific effects on epigenetic entropy were observed, indicating differential patterns in the loss of epigenetic stability over time. Constructing an epigenetic clock containing 19 CpGs revealed a robust correlation between epigenetic age and chronological age. Conclusions: Nasonia vitripennis emerges as a promising model for investigating the epigenetics of ageing, shedding light on the intricate dynamics of DNA methylation and their implications for age-related processes. This research not only expands the repertoire of ageing models but also opens avenues for deeper exploration of epigenetic mechanisms in the context of ageing
Do alliances make firms faster?
Get PDFAlliances are typically viewed as an acceleration strategy for firms able to access or acquire the resources and capabilities of partner firms, yet theoretical and empirical work suggests that alliances can actually impair speed performance due to the costs stemming from partner cooperation and coordination. In this paper, we advance the premise that firm heterogeneity may determine whether alliances enhance, or impair, the speed performance of firms. We then turn to focus on one particular kind of firm heterogeneity, the intrinsic speed capabilities of the firm, by which we mean the ability to execute investment projects or operations faster at the same cost. Our expectation is that slow firms, or those firms lacking intrinsic speed capabilities, will realize substantial speed benefits from partnering due to the capability access from partner firms. We also expect that the benefits enjoyed by slow firms from partnering can persist into future projects due to capability acquisition from the partnership, but that these benefits hinge on the firm possessing absorptive capacity in the form of previous partnering experiences. Results from random coefficient models that address selection concerns and from treatment effect analyses provide support for these expectations in on-shore oil and gas drilling projects
Methodologies for the synthesis of β-carbolines
No full textβ-Carbolines are an important class of heterocyclic compounds that are widely distributed in nature, being found in several families of naturally occurring alkaloids. Due to their diverse biological activities, the synthesis of β-carbolines is of high importance. Besides traditional methodologies, like the Pictet-Spengler and the Bischler-Napieralski reaction, many alternative strategies have been developed for the synthesis of the β-carboline motif. This review summarizes methodologies and strategies for the synthesis of β-carbolines published between 2000 and 2021
To be called forth by a speck of dust
Get PDFLess a response, this commentary is a conversation with Anna Secor's ‘Spacetimeunconscious’, riffing off its offering. I trace one of the playful characters in Secor's article, the speck of dust that shapeshifts across the paper's 18 pages, folding and dispersing geographies and temporalities. I am wrestling with how to make sense of geographies that I care about, exactly at the same moment when these geographies are blown up into shards all over my screen. And I would like to think of Secor's paper as a companion for me, and for those who might be trying to figure a way to face the slow and fast breakdown of the surfaces of the present; a supplement, rather than an answer, to the question of where do we go from here, now
Crystal growth and Hall effect of the non-centrosymmetric superconductor α-BiPd and the topological superconductor β-Bi2Pd
No full textDue to the rarity of triplet pairing, topological superconductors (SCs) have primarily been realized experimentally in manufactured topological phases, such as heterostructures, where the proximity effect causes triplet pairing with traditional s-wave SCs. Recently, there has been a lot of interest in investigating novel quantum materials with spin-triplet pairs in order to develop Majorana physics and creating quantum computers. Bi-based superconductors are speculated to hold promise for realizing spin-triplet pairing due to its large spin orbit coupling. In this work, we present the growth of α-BiPd and β-Bi2Pd single crystals using the optical floating zone technique and their characterization. The single crystals of α-BiPd and β-Bi2Pd are found to crystallize in monoclinic and tetragonal crystalline system with space group P21 and I4/mmm, respectively. The composition and microstructure of the grown crystals were analyzed with a scanning electron microscope, through energy dispersive spectroscopy (EDS) and electron backscattered diffraction (EBSD) analysis. The superconducting behavior and Hall effect of both α-BiPd and β-Bi2Pd single crystals have been investigated through resistivity measurements
Characterisation of the R2R3 Myb subgroup 9 family of transcription factors in tomato
Get PDFTomato (Solanum lycopersicum) has many epidermal cell outgrowths including conical petal cells and multiple types of trichomes. These include the anther-specific trichome mesh which holds the anthers connate. The R2R3 Myb Subgroup 9 family of transcription factors is involved in development of epidermal cell outgrowths throughout the angiosperms. No previous study has examined all members of this transcription factor family in a single species. All 7 R2R3 Myb Subgroup 9 genes were isolated from tomato. They were ectopically expressed in tobacco to assess their ability to induce epidermal cell outgrowth. Endogenous expression patterns were examined by semi-quantitative RT-PCR at different stages of floral development relative to the development of anther trichomes. We report variation in the degree of epidermal cell outgrowth produced in transgenic tobacco by each ectopically expressed gene. Based on expression profile and ectopic activity, SlMIXTA-2 is likely involved in the production of leaf trichomes. SlMIXTA-2 is expressed most strongly in the leaves, and not expressed in the floral tissue. SlMYB17-2 is the best candidate for the regulation of the anther trichome mesh. SlMYB17-2 is expressed strongly in the floral tissue and produces a clear phenotype of epidermal cell outgrowths when ectopically expressed in tobacco. Analysis of the phenotypes of transgenic plants ectopically expressing all 7 genes has revealed the different extent to which members of the same transcription factor subfamily can induce cellular outgrowth