Browse Articles
Discover research articles across all indexed journals
Spike-based alignment learning solves the weight transport problem
Abstract Learning algorithms are often subject to symmetry constraints that are difficult to reconcile with local computation in physical neuronal networks. For example, contrastive Hebbian learning typically assumes symmetric connectivity, while error backpropagation requires knowledge of the forward weights in the backward pass. To solve this weight transport problem, we introduce spike-based alignment learning (SAL), a synapse-local learning rule that harnesses noise for weight alignment. This rule can operate simultaneously with other functional learning rules to maintain the necessary symmetry throughout learning and thereby ensure the correct local representation of gradients. SAL implicitly alleviates any discrepancy arising from the neuron and synapse variability that is ubiquitous in analog substrates, whether biological or artificial. We demonstrate the efficacy of our mechanism using different network models for spiking Bayesian inference and bio-plausible error backpropagation, and benchmark it in a deep learning computer vision task.
Impact of tropical Atlantic on ENSO predictability in SEAS5-20C
Author Correction: Eliminating lead-exposure in nebulization therapy by lead-free piezoelectric
Optimization of dry chemomechanical and deep eutectic solvent pretreatment of mango peel biomass for enhanced lignin removal
Astrocytic ankyrin-2 enables memory persistence in the mouse hippocampus
Abstract Memory persistence, the ability to retain information over time, is a fundamental feature of long-term memory. Although astrocytes contribute to synaptic plasticity, the molecular mechanisms by which they support memory persistence remain unclear. Here we show that astrocytic ankyrin-2 (Ank2) is required for memory persistence in adult mice. Astrocyte-specific deletion of Ank2 impaired remote memory without affecting recent memory and disrupted the maintenance of long-term potentiation. Loss of Ank2 reduced astrocyte contacts with engram neurons and impaired astrocyte morphogenesis driven by brain-derived neurotrophic factor (BDNF) signaling through the truncated tropomyosin receptor kinase B receptor (TrkB.T1) and inositol 1,4,5-trisphosphate receptor type 2 (IP3R2). Consistent with this mechanism, astrocytic Ank2 was required for the enhancement of memory persistence by hippocampal BDNF infusion. Furthermore, selective optogenetic activation of astrocytic TrkB.T1 signaling enhanced remote memory, demonstrating that astrocytic BDNF signaling is sufficient to promote memory persistence. These findings identify astrocytic Ank2 as a key regulator of long-term memory persistence.
Fully illustrated morphological keys to the fleas (Siphonaptera) of Iran from superfamily to subspecies level
Abstract Iran’s strategic geographic position, its historical role in major trade routes such as the Silk Road, and its proximity to plague-endemic regions have repeatedly exposed it to plague outbreaks. The most recent documented epidemic occurred in 1966 in Sarab, East Azerbaijan Province. Historically, these outbreaks have significantly influenced demographic patterns, socioeconomic structures, and political developments. In response, extensive research has been conducted to investigate the diversity of Yersinia pestis -vectoring fleas (Siphonaptera) in Iran, resulting in the identification of 119 species and subspecies across diverse ecological zones. Despite these efforts, a comprehensive, up-to-date, and user-friendly set of morphological identification keys—covering taxa from superfamily to subspecies level—has been limited to outdated or regionally restricted resources. The present study addressed this critical gap by presenting fully illustrated dichotomous keys for Iranian fleas, based on detailed morphological characteristics of both male and female adults. High-resolution images, accompanied by precise annotations, emphasize diagnostic features essential for distinguishing sibling species and other morphologically similar taxa. The primary objective of this work is to enhance the accuracy of flea taxonomy and to strengthen surveillance and control programs targeting flea-borne diseases, particularly in Iran’s plague-endemic areas.
Quantifying the net effect of biodiversity on ecological stability
Abstract Understanding the relationship between biodiversity and both the functioning and stability of ecosystems has been a central focus of ecologists for decades. A step-change in our understanding of the biodiversity–ecosystem functioning relationship was enabled by explicit measurement of the additional functioning provided by biodiversity through comparing expected and observed yields in multi-species communities. However, we lack an equivalent measure for stability. Here, we quantify the net biodiversity effect on stability using model simulations and a microcosm experiment that exposes different phytoplankton species and their combinations to temperature increases and fluctuations. As an emergent property of communities, stability frequently exceeds the expected stability of the combined component species, leading to a net biodiversity effect on stability analogous to the effect on functioning. In our simulations, these effects depend on the strength of competitive interactions as well as species composition and their thermal optima. Experimentally, the stabilising effect of biodiversity is, however, non-linear, greatest for two-species combinations, and varies with both community composition and disturbance regime. Quantifying the net biodiversity effect on ecological stability advances our mechanistic understanding of the biodiversity–stability relationship, and provides crucial information to support ecosystem management and conservation.
Conformation-dependent donor selectivity in the xanthan gum glycosyltransferase GumK revealed by AI-based docking
Abstract The interdomain flexibility of GT-B fold glycosyltransferases regulates substrate binding and catalysis, yet the role of local structural variations in donor substrate specificity remains unclear. GumK, a GT70 enzyme from Xanthomonas campestris , exhibits local plasticity within its donor-binding pocket. We classify this plasticity into two conformational states, defined by the presence (closed state) or absence (open state) of a conserved hydrophobic interaction stabilizing the pocket. Using the AI-enhanced docking approach GNINA, we investigated the relationship between these states and substrate specificity by comparing UDP-glucuronate with five acidic and neutral ligand analogs. While docking scores showed limited discrimination among ligands, distance-based analysis between the sugar C6 atom and Lys307 revealed conformation-dependent trends. In the open state, negatively charged sugars preferentially interact with Lys307 via their carboxylate groups. Conversely, the closed state favors interactions with the pyrophosphate moiety. To provide orthogonal validation, we generated ensembles of GumK–substrate complexes using AI-based cofolding methods (AlphaFold3 and Boltz). While Boltz-2 affinities correctly ranked substrate specificity, only the GNINA-generated ensembles were consistent with physics-based simulations in capturing the conformational basis of selectivity. These results suggest that donor specificity arises from the interplay between ligand chemistry and binding-site plasticity rather than from a single rigid binding mode, and highlight complementary strengths of docking and cofolding approaches for studying flexible CAZymes.
Cationic carbon nanotube modulates surface fields for general acidic CO2 reduction with aqueous organic cations
Distributed fuzzy clustering approach for balanced energy consumption in large-scale networks
Substrate recognition and transport mechanism of the human proton-coupled amino-acid transporter 1 (SLC36A1)
Bullous keratopathy associated with a shallow anterior chamber: An anatomical risk phenotype for corneal endothelial decompensation
Purpose To characterize bullous keratopathy (BK) associated with a shallow anterior chamber (AC) and to examine whether a shallow AC itself may be associated with corneal endothelial decompensation, even in the absence of acute primary angle closure (APAC) or argon laser iridotomy (ALI). Methods This multicenter retrospective observational study included 96 eyes that underwent Descemet membrane endothelial keratoplasty (DMEK) for endothelial dysfunction between 2015 and 2025 with ≥12 months of follow-up. The primary comparative analyses compared eyes with Fuchs endothelial corneal dystrophy (FECD) and eyes with endothelial dysfunction associated with a shallow AC. The shallow anterior chamber phenotype group comprised eyes with a documented history of APAC or ALI (PACD/ALI) and those without a documented history of either condition (shallow-AC). Anterior chamber depth (ACD), axial length, corneal thickness, endothelial parameters, and postoperative outcomes were compared between groups. Results Pre-cataract ACD was significantly shallower in the shallow anterior chamber phenotype group than in the FECD group (1.93 ± 0.40 mm vs. 2.28 ± 0.27 mm, P < 0.001), and this relative difference persisted after cataract surgery. Within the shallow anterior chamber phenotype group, 10 eyes were classified as shallow-AC and had no documented history of APAC or ALI. Five-year graft survival after DMEK exceeded 90% and did not differ significantly between the shallow anterior chamber phenotype and FECD groups, nor between PACD/ALI and shallow-AC subgroups. Conclusions A shallow anterior chamber may be associated with corneal endothelial decompensation, even in the absence of APAC or ALI. With appropriate perioperative management, DMEK may provide favorable long-term outcomes in these eyes.
An improved auxiliary circuit based MMC for the reduction of ripple content in the module voltage
Robust estimates of biodiversity change require high-resolution time series
Abstract Robust estimates of biodiversity change are essential to inform management and conservation, and to address global biodiversity loss. However, common temporal data limitations may compromise trend accuracy. Here, we test how temporal resolution influences biodiversity trends using 1,353 river invertebrate time series collected annually for ≥ 10 years across 18 European countries. We simulate reduced sampling frequencies and durations and compare these trends to the complete time series. Reducing frequency from annual to every 2–6 years resulted in 87–73% of sites matching in trend directions, but only 78–39% matching in magnitude. Reducing duration from 10 to 9–2 years resulted in 88–52% direction matches and 86–8% magnitude matches. Similar results were observed for longer time series ( ≥ 20 years). Additionally, a comparison of two real-world monitoring datasets with different temporal resolutions shows that 53% of sites matched in direction, but only 12% in magnitude. Our findings indicate that biodiversity change magnitude is more sensitive to temporal resolution than direction. Consequently, accurate estimates of both direction and magnitude require high-resolution time series, whereas lower-resolution data may only reliably capture direction. These results highlight the value and limitations of temporal biodiversity data, and help plan future monitoring.
Plasma cell-free DNA measured prior to renal replacement therapy initiation is not associated with incident adverse outcomes, hospitalizations or malignancies in chronic kidney disease stage 4–5 patients
Inflammation is an inherent feature of advanced chronic kidney disease (CKD) and associated with adverse outcomes. Several inflammatory biomarkers have been shown to be associated with mortality in CKD. Cell-free DNA (cfDNA) is a novel biomarker for inflammation which has not been previously examined in patients with CKD stage 4–5 not undergoing dialysis. cfDNA was extracted from plasma and quantified with Qubit Flex Fluorometer using dsDNA High Sensitivity kit in 138 patients with CKD stage 4–5 not undergoing dialysis at baseline and at a control time point of median 2.7 years of follow-up. A ratio of control and baseline measurement adjusted for an increment of one year of follow-up was calculated. Associations between cfDNA at baseline and all-cause mortality, major adverse cardiovascular and cerebrovascular events (MACCE, defined as a composite outcome of acute myocardial infarction, coronary revascularization, ischemic or hemorrhagic stroke and cardiovascular death), emergency room (ER) visits, hospitalizations or incident malignancies were assessed. Within a median follow-up of 6.2 years, no associations were observed between cfDNA and mortality, MACCEs, ER visits, hospitalizations or incident malignancies. cfDNA control measurement and cfDNA delta ratio was available in 101 patients. Patients who had received a kidney transplant by the control cfDNA measurement had significantly higher cfDNA delta ratio compared to patients not on renal replacement therapy (RRT) and those undergoing dialysis (p < 0.001 for both comparisons). Patients undergoing dialysis at the time of the control cfDNA measurement had higher cfDNA delta ratio (p = 0.003) compared to patients not on RRT. The present study is the first to show that cfDNA is not associated with adverse outcomes in patients with advanced CKD not undergoing dialysis at baseline. Furthermore, our results provide unique data on the evolution of cfDNA levels in predialysis CKD stage 4–5 patients transitioning to different modalities of RRT.
Scale dependent Forchheimer flow in bioturbated limestone characterised by CT imaging and multi scale CFD analysis
Full vibrational spectroscopy for simultaneous mechanical, structural and chemical analysis
Abstract The light scattered inelastically from molecular vibrations occurring at different temporal and spatial scales carries intrinsic physical information about the illuminated sample. Mechanical, structural and chemical properties can be simultaneously retrieved by analyzing the full vibrational spectrum in different frequency ranges, yet strong elastic scattering near the laser frequency typically overwhelms the low-frequency region. Here, we present a method for measuring the full vibrational spectrum from 0.1 to > 3,500 cm −1 using a Birefringence-Induced Phase Delay filter with high extinction ratio and ultranarrow bandwidth for efficient elastic suppression. Our multimodal, label-free approach enables the simultaneous acquisition of Brillouin, ultra-low-frequency Raman (ULFR), and Raman spectra from the same illumination voxel. We demonstrate the method acquiring Brillouin, ULFR, and Raman spectra from active pharmaceutical ingredients, revealing previously inaccessible distinctions in the amorphous forms of indomethacin and its mixtures with polyvinylpyrrolidone excipients. We further extended our approach to full vibrational imaging by acquiring maps of an ibuprofen tablet. Our findings demonstrate the high sensitivity and specificity of the multimodal platform to analyze chemical content while investigating mechanical and structural heterogeneities. Results open promising avenues in biomedical research and material science where key physical properties can be optically retrieved simultaneously at diffraction-limited spatial resolution.
Longitudinal associations of academic stress with eating related patterns, nutrition, somatic indicators, and depressive symptoms in university students: A study protocol
Introduction Academic stress (AS) can be understood as a multidimensional form of chronic stress that has been linked to adverse patterns across physical and mental health in university students. This protocol outlines a longitudinal, observational study to examine within-semester associations between AS and indicators of nutritional status, eating-related patterns, sleep quality, and depressive symptoms. By integrating physiological, behavioral, and psychological indicators within a repeated-measures framework, the study aims to generate evidence that can inform prevention-focused actions and early support strategies in university health contexts. Hypotheses (i) Higher AS will be longitudinally associated with less favorable eating-related patterns, nutritional and somatic indicators, and higher depressive symptoms in university students. (ii) Higher AS will be associated with altered post-awakening cortisol dynamics, specifically a lower cortisol awakening response (CAR) and lower AUCi, together with a higher AUCg, and with higher salivary alpha-amylase (sAA) levels, consistent with stress-related activation of HPA-axis and sympathetic pathways. Design and participants A longitudinal, observational, nonexperimental design with repeated measurements will be implemented across three assessment cycles during an academic semester. A feasibility-based convenience sample will be recruited from undergraduate students (2nd to 4th year) enrolled in the Faculty of Medicine, University of Concepción (Chile). Students receiving psychological or pharmacological treatment will be eligible to reflect real-world heterogeneity and support ecological validity. Methods Data will be collected through standardized questionnaires, nutritional assessments, biological sampling, and wearable-derived somatic indicators. Electronic surveys administered via REDCap will assess AS, perceived stress, eating-related patterns, and depressive symptoms. Diet will be assessed through interviewer-administered nutritional interviews, including repeated 24-hour dietary recalls treated as time-specific observations and modeled longitudinally as time-varying measures, and complemented by diet-quality and dietary inflammatory potential indices. Wearable devices will record nonclinical somatic indicators, including heart rate, oxygen saturation, and sleep-related metrics during monitoring periods. Saliva will be collected twice per week during each assessment cycle to quantify salivary cortisol dynamics and sAA activity, and peripheral blood samples obtained at baseline and end of semester will be used to determine lipid profile, fasting glucose, albumin, globulin, and total proteins. Statistical analysis Analyses will include descriptive and bivariate summaries, followed by multivariable models appropriate to outcome type. Longitudinal associations will be examined using mixed-effects models, and temporal cross-lagged associations will be explored using random-intercept cross-lagged panel models across the three assessment cycles. All inferences will be framed as associational given the observational design. Expected results Rather than prespecifying outcomes, this protocol is expected to generate longitudinal evidence on how within-semester variation in AS aligns with eating-related patterns, diet, nutritional and somatic indicators, depressive symptoms, and stress-related physiological indicators (salivary cortisol dynamics and sAA activity). The integrated, feasibility-oriented measurement framework may serve as a replicable template for future research and inform prevention-focused actions to support student well-being in university settings.