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Family imprint reveals basin-wide patterns of Amazon forest embolism resistance
Get PDFAmazon rainforests face intensifying water stress due to increases in vapour pressure deficit and changing hydrological regimes. Embolism resistance (Ψ50) is a critical metric of tree survival under drought conditions, it is defined as a plant’s capacity to resist disruption of xylem water flow due to air bubble formation from water stress. However, measurements of Ψ50 are only available for a limited number of Amazon locations and species. Conversely, data on forest taxonomic composition are abundant across Amazonia, and if Ψ50 is conserved phylogenetically, these data could provide a way to scale-up drought resistance patterns. Here we evaluate Ψ50 measurements across non-flooded Amazonian tree taxa and reveal a moderate phylogenetic signal, with phylogenetic conservatism evident at the family-level. Notably, Fabaceae is amongst the most embolism-resistant tree families in Amazonia. Leveraging the phylogenetic signal we use species composition and tree size data from 448 forest plots across Amazonia to produce a macroecological assessment of Amazonian vulnerability to embolism. The resulting estimate spatial pattern reveals that forests in the Brazilian and Guiana Shield regions, where Fabaceae abundance is high, show strong resistance to embolism. In contrast, tree communities in Western Amazonia appear more vulnerable to embolism, suggesting a reduced capacity to withstand future drought conditions
Ethical issues in neurosurgery - A scoping review from the EANS Ethico-legal committee
Get PDFBackgroundEthical considerations are integral to neurosurgical decision-making, yet emerging technologies, demographic shifts, and global crises continuously introduce new challenges. Key ethical concerns include patient autonomy, prioritization, the value of life, research ethics, and personality-altering procedures. Despite their importance, formal ethics training for neurosurgical residents is often lacking, and guideline application remains inconsistent. This scoping review summarizes current literature on ethical issues in neurosurgery, identifies key topics and assessment methods, and highlights research priorities to enhance ethical awareness.MethodsA systematic literature search was conducted in Medline, Embase, and Web of Science using the search strategy (Ethic∗[Title]) AND (neurosurg∗[Title]). The search, performed on October 8, 2024, yielded 334 records (1985-2024). After removing duplicates and screening, 13 studies met inclusion criteria. Two independent reviewers selected original research in English or German addressing ethical neurosurgical issues, excluding opinion pieces, reviews, and case reports. Extracted data included study characteristics, country, year, topic, design, and key findings.ResultsFrom a neurosurgical perspective, six ethical subcategories emerged: decision-making (31 %), pediatric neurosurgery (23 %), neurosurgery in developing countries (15 %), artificial intelligence (15 %), functional neurosurgery (8 %), and patient care (8 %). From a classical ethical standpoint, seven studies (53.8 %) focused on psychosocial ethical issues, four (30.7 %) examined normative ethical questions, and two (15.4 %) addressed aspects of professional ethics. All studies employed a qualitative research design. Most studies (77 %) used questionnaires or structured interviews for data collection. Findings revealed regional differences in ethical decision-making, increasing reliance on hospital ethics committees, resource-related dilemmas in low-income countries, and emerging AI-related concerns. Despite growing interest, structured assessment methods and standardized ethics education remain limited.ConclusionsEthical challenges in neurosurgery, as explored through the lenses of indirect sources (published literature), are diverse and shaped by technological advancements and sociopolitical factors. AI-related ethics and crisis-driven dilemmas, such as those arising from wars and pandemics, are gaining attention. However, research methodologies remain inconsistent, limiting data comparability. Future studies should focus on enhancing ethics training and developing standardized frameworks for ethical analysis improving neurosurgical ethical decision-making
SomaVR: A low-cost virtual reality platform and implementation framework for medical education in resource-limited settings
Get PDFQuality medical training is vital for effective healthcare worldwide. In low- and middle-income countries (LMICs), traditional training methods often face significant challenges, including limited resources, logistical barriers, and difficulties in safely replicating high-risk scenarios for infectious diseases like COVID-19 and Ebola. Additionally, medical training demands high costs, significant time, and specialized supervision, limiting its accessibility. Although virtual reality (VR) offers promising solutions to these problems, most evidence comes from high-income settings, leaving limited guidance on implementation in resource-constrained settings. We developed SomaVR, a low-cost VR platform and implementation framework for medical training in LMICs. Built with Unity3D, ‘SomaVR’ (soma - Swahili/Luganda for “to learn”) integrates 360-degree and interactive virtual environments to create customizable training experiences aligned with specific curricula needs. Beyond the software, the framework provides a structured approach covering hardware selection, software architecture, content development workflows, and strategies for local capacity building. The platform prioritizes cross-platform compatibility, offline functionality, and cost-effective deployment. SomaVR’s modular components support both high-end VR systems and low-cost solutions such as smartphone-based. The platform and framework were validated through two independent case studies: 1. COVID-19 infection prevention; and 2. Surgical training. In the surgical training, trainers from a high-income country guided Ugandan learners remotely, illustrating SomaVR’s potential for long-distance knowledge exchange. In both cases, cohorts trained using SomaVR consistently outperformed those receiving conventional training, with significant improvements in procedural understanding and user engagement. Our findings also highlight that as VR technology costs decline, frugal approaches such as delivering 360-degree video via smartphone can maintain educational effectiveness in low-resource environments. This paper provides a practical blueprint for developing and implementing sustainable VR medical training platforms in resource-limited settings. By detailing the technical framework, development processes, and implementation strategies of SomaVR, we offer a replicable model for institutions seeking to leverage VR technology for medical education in LMICs
String diagrams for quantum foundations, computing and natural language processing
Get PDFApplied category theory provides powerful mathematical tools for modelling processes and their composition. Symmetric monoidal categories, which involve series and parallel composition, are particularly well-suited for describing the composition of processes in space and time. Also called process theories, they admit string diagrams, which constitute a visually intuitive, mathematically rigorous, expressive and flexible syntax that is applicable to wide-ranging scientific domains.
In this thesis, we employ string diagrams to investigate a selection of topics in the areas of quantum foundations, computing, and natural language processing. We report three main contributions:
• We formalise constructor theory as a process theory. In the context of quantum physics, we also demonstrate the conflict between constructor-theoretic principles of locality and composition. Moreover, we argue that if the principle of locality is rejected, categorical quantum mechanics (CQM) can be conceived as a constructor theory of quantum physics.
• We develop a formalism for wave-based logic circuits with phase encoding. We motivate the formalism using the example of spin-wave circuits, and then demonstrate its utility in design, analysis and optimisation of Boolean logic circuits.
• We investigate the elimination of inter-language grammatical bureaucracy in the distributional compositional circuits (DisCoCirc) framework. In particular, we develop a hybrid grammar for a restricted fragment of the Urdu language, and show that Urdu text endowed with this hybrid grammar maps surjectively to DisCoCirc text circuits. Furthermore, we show that for the same language fragment, Urdu and English text circuits become the same up to gate-level translation.
The aforementioned work supports the view that a process-relational outlook in science is well-supported by applied category-theoretic tools, particularly string diagrams
Exoplanet atmospheres at high spectral resolution
No full textThe spectrum of an exoplanet reveals the physical, chemical, and biological processes that have shaped its history and govern its future. However, observations of exoplanet spectra are complicated by the overwhelming glare of their host stars. Here, we focus on high-resolution spectroscopy (HRS) (R∼5,000−140,000), which helps disentangle and isolate the exoplanet’s spectrum. HRS resolves molecular features into a dense forest of individual lines in a pattern that is unique for a given molecule. For close-in planets, the spectral lines undergo large Doppler shifts during the planet’s orbit, while the host star and Earth’s spectral features remain essentially stationary, enabling a velocity separation of the planet. For slower-moving, wide-orbit planets, HRS, aided by high contrast imaging, instead isolates their spectra using their spatial separation (high contrast spectroscopy; HCS). The planet’s spectral lines are compared with HRS model atmospheric spectra, typically using cross-correlation to sum their signals. It is essentially a form of fingerprinting for exoplanet atmospheres and works for both transiting and non-transiting planets. It measures their orbital velocity, true mass, and simultaneously characterizes their atmosphere. The unique sensitivity of HRS to the depth, shape, and position of the planet’s spectral lines allows it to measure atmospheric composition, structure, clouds, and dynamics, including day-to-night winds and equatorial jets, plus its rotation period and even its magnetic field. These are extracted using statistically robust log-likelihood frameworks and match space-based instruments in their precision. This chapter describes the HRS technique in detail and concludes with future prospects with Extremely Large Telescopes to identify biosignatures on nearby rocky worlds and map features in the atmospheres of giant exoplanets
RECUR: identifying recurrent amino acid substitutions from multiple sequence alignments
Get PDFIdentifying recurrent changes in biological sequences is important to multiple aspects of biological research—from understanding the molecular basis of convergent phenotypes, to pinpointing the causative sequence changes that give rise to antibiotic resistance and disease. Here, we present RECUR, a method for identifying recurrent amino acid substitutions from multiple sequence alignments that is fast, easy to use, and scalable to thousands of sequences. We demonstrate that RECUR's recurrence detection achieves 100% accuracy on simulated data with known evolutionary histories. We further show that RECUR is robust to realistic levels of tree inference error. Finally, we apply RECUR to a large set of surface glycoprotein (S) protein sequences from SARS-CoV-2. This analysis identified widespread recurrent evolution throughout the protein with significant enrichment in the exposed receptor-binding S1 subunit and at the interface with the human angiotensin-converting enzyme 2 (hACE2). In contrast, recurrent substitutions were depleted at the trimeric interface of the S protein. In silico modelling showed that recurrent substitutions had no directional effect on stability at either interface, but effects at the hACE2 interface were significantly more variable. Multiple substitutions with large destabilizing effects on hACE2 binding have been linked to immune escape, while others represented reversions back to the reference sequence, suggesting that recurrent evolution at this interface reflects opposing selective pressures balancing receptor binding with immune evasion. A standalone implementation of the algorithm is available under the GPLv3 license at https://github.com/OrthoFinder/RECUR
Measuring the Central Dark Mass in NGC 4258 with JWST/NIRSpec Stellar Kinematics
Get PDFWe present a new stellar-dynamical measurement of the supermassive black hole (SMBH) mass in the nearby spiral galaxy NGC 4258 (M106), a critical benchmark for extragalactic mass measurements. We use archival James Webb Space Telescope (JWST) Near-Infrared Spectrograph (NIRSpec) integral field unit data (G235H/F170LP grating) to extract high-resolution two-dimensional stellar kinematics from the CO bandhead absorption features within the central 3″ × 3″. We extract the stellar kinematics after correcting for instrumental artifacts and separating the stellar light from the nonthermal active galactic nucleus (AGN) continuum. We employ Jeans anisotropic models to fit the observed kinematics, exploring a grid of 12 models to systematically test the impact of different assumptions for the point-spread function, stellar mass-to-light ratio profile, and orbital anisotropy. All 12 models provide broadly acceptable fits, albeit with minor differences. The ensemble median and 68% (1σ) bootstrap confidence interval of our 12 models yield a black hole mass of MBH=(4.08−0.33+0.19)×107 M⊙. This paper showcases the utility of using the full model ensemble to robustly account for systematic uncertainties, rather than relying on formal errors from a single preferred model, as has been common practice. Our result is just 5% larger than, and consistent with, the benchmark SMBH mass derived from water-maser dynamics, validating the use of NIRSpec stellar kinematics for robust SMBH mass determination. Our analysis demonstrates JWST’s ability to resolve the SMBH’s sphere of influence and deliver precise dynamical masses, even in the presence of significant AGN continuum emission
Vertically Aligned Micro‐ and Nanoneedles for Advanced Biomedical Applications: From Fabrication Strategies to Clinical Translation
Get PDFEffective therapeutic delivery and diagnostic monitoring at cellular levels are constrained by biological barriers including stratum corneum, extracellular matrix, and plasma membranes. Conventional approaches such as viral vectors and liposomes face limitations including inadequate penetration, immunogenicity, and invasiveness. High‐aspect‐ratio nanostructures, including nanoneedles and microneedles, address these challenges through their unique geometries enabling direct, minimally invasive cellular access. This review examines high‐aspect‐ratio nanostructure technologies from fabrication strategies to therapeutic and diagnostic applications. We discuss bottom‐up synthesis, top‐down lithographic methods, and integrative approaches enabling precise control over geometry, mechanical properties, and surface functionalization. Mechanotransduction applications reveal how these architectures modulate cellular behavior through mechanosensitive pathways and enable phenotypic control. Recent advances have expanded applications to precision medicine through intracellular delivery of genetic engineering tools to challenging cell populations including immune cells and neurons. Hollow, porous, and surface‐functionalized architectures enable controlled therapeutic release and targeted cellular reprogramming. Diagnostic applications demonstrate capabilities for intracellular sensing and continuous physiological monitoring. Convergence with artificial intelligence promises adaptive, personalized therapeutic protocols. However, challenges including scalable manufacturing, long‐term biocompatibility, and regulatory translation must be addressed to realize clinical potential. This review positions high‐aspect‐ratio nanostructures as foundational platforms for next‐generation precision medicine and personalized healthcare
From mount to manuscript: revisiting commodity terms in a mugh document
Get PDFIn the spring of 1932, a shepherd fortuitously discovered a wicker basket containing a manuscript at Mount Mugh, Tajikistan. This paper manuscript, later labeled 1.I,1 written in a script then unknown in the region and preserved today only in a photograph, paved the way to one of the most significant archives of early medieval Central Asia, comprising approximately 75 documents in Sogdian, alongside one in Arabic, one in Old Turkic, and three in Chinese. The Sogdian documents from Mount Mugh provide a unique local perspective on the political, social, and economic life of Sogdiana during its arguably most turbulent period, the Arab-Muslim conquest
Travelling in troubled times: a Latin letter of safe passage for a Muslim merchant issued during the Frankish-Fatimid wars
Get PDFA single photograph of a letter of safe passage is all that remains of the documentary trail of a Muslim merchant travelling through the northern reaches of the Latin Kingdom of Jerusalem decades after the city’s violent takeover by the first crusaders in 493/1099. The document can be classed as a letter close, or royal writ granting permission for an action, intended to be opened and used only once. It is the only known example of a letter close issued by a sovereign of Latin Jerusalem in its original format. The majority of the chancery’s original documents were likely lost during the conquest of the reduced Kingdom of Jerusalem by the sultan of Cairo, al-Ashraf Khalīl (reigned 689–693/1290–1293), in 690/1291.