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A designer minimalistic model parallels the phase-separation-mediated assembly and biophysical cues of extracellular matrix
No full textThe propensity for controlled liquid–liquid phase separation and subsequent directed phase transition are crucial for the coacervation-mediated assembly of extracellular matrix (ECM). This spatiotemporally controlled ECM assembly can be used to develop coacervate-based polymer assembly strategies to generate biomimetic materials that can emulate the complex structures and biophysical cues of the ECM. Inspired by the tropoelastin structure, here we develop a designer minimalistic model consisting of alternating hydrophobic moieties and covalent crosslinking domains. By increasing the valence and enhancing the interaction strength of the hydrophobic moieties, we can control the degree of the assembly to enhance the propensity for phase separation and thus emulate the extracellular coacervation process of tropoelastin, including droplet formation, coalescence and maturation. The subsequent covalent-bonding-triggered coacervate–hydrogel transition with enhanced assembly order stabilizes the phase-separated structure in the form of a heterogeneous hydrogel, thereby mimicking covalent crosslinking-derived elastin fibrillation. Furthermore, the heterogeneous hydrogel network establishes a biomimetic matrix that can effectively promote the mechanosensing of adherent stem cells. (Figure presented.)</p
Foldable Inverted Perovskite Solar Cells Enabled by Region-Dependent Microscopic and Macroscopic Strain Relaxation
Get PDFWhile foldable solar cells can advance the applications from emerging electronics like self-powered wearable optoelectronic devices, the poor mechanical durability of perovskite films due to the severe intrinsic strain, and the brittle nature of the flexible ITO electrode hinder foldable perovskite solar cells (F-PSCs) realization. Here, the strategy of region-dependent microscopic and macroscopic strain suppression is demonstrated to achieve efficient F-PSCs on silver nanowires (AgNWs) electrodes. Fundamentally, by introducing the region-dependent modification approach of functionalized polymer incorporation, the significant release of microscopic strain in perovskite film is demonstrated by effectively suppressing defects at places with crystallization orientation variation of perovskite surface/grain boundaries. Equally important, the gradient macroscopic strain is simultaneously eliminated by inhibiting the FA+ (formamidinum) gradient distribution in perovskite film's depth direction. The two-strain relaxations greatly enhance the mechanical durability of perovskite film, while also improving phase stability and suppressing ion migration. Finally, efficient F-PSCs (23% PCE, the highest value among reported F-PSCs) is realized with remarkable foldability, with efficiency maintaining 94% of its initial value even after 2000 times multidirectional folding at 0.75 mm curvature radius, which far exceeds the mechanical durability of typical ITO-based flexible PSCs. This work aids in comprehending strain modulation role for F-PSCs realization.published_or_final_versio
BDLUT: Blind image denoising with hardware-optimized look-up tables
Get PDFDenoising sensor-captured images on edge display devices remains challenging due to deep neural networks' (DNNs) high computational overhead and synthetic noise training limitations. This work proposes BDLUT(-D), a novel blind denoising method combining optimized lookup tables (LUTs) with hardware-centric design. While BDLUT describes the LUT-based network architecture, BDLUT-D represents BDLUT trained with a specialized noise degradation model. Designed for edge deployment, BDLUT(-D) eliminates neural processing units (NPUs) and functions as a standalone ASIC IP solution. Experimental results demonstrate BDLUT-D achieves up to 2.42 dB improvement over state-of-the-art LUT methods on mixed-noise-intensity benchmarks, requiring only 66 KB storage. FPGA implementation shows over 10 (Formula presented.) reduction in logic resources, 75% less storage compared to DNN accelerators, while achieving 57% faster processing than traditional bilateral filtering methods. These optimizations enable practical integration into edge scenarios like low-cost webcam enhancement and real-time 4 K-to-4 K denoising without compromising resolution or latency. By enhancing silicon efficiency and removing external accelerator dependencies, BDLUT(-D) establishes a new standard for practical edge imaging denoising. Implementation is available at https://github.com/HKU-LiBoyu/BDLUT.published_or_final_versio
Reachable Set Estimation of Switched Systems With All Subsystems Unstable
No full textReachable set estimation of switched systems consisting entirely of unstable subsystems poses a challenge that remains unsolved, particularly when employing Lyapunov methods. In this work, a lemma for bounding the Lyapunov functions of switched continuous-time systems with dwell time confined to a bounded interval is proposed. For switched systems with all subsystems unstable, the main difficulty in estimating the reachable set is that conventional constant symmetric positive definite matrices in the quadratic Lyapunov functions (referred to as Lyapunov matrices in this work) will lead to infeasible conditions due to parameter restrictions. To obtain implementable reachable set estimation conditions, our novelty is constructing time-varying Lyapunov matrix functions to develop sufficient conditions for enclosing the reachable set of all unstable subsystems. The core idea is to use the derivatives of matrix functions over a finite time domain to compensate for restrictions on parameters. Furthermore, a linear interpolation approach is utilized to enable time-varying Lyapunov matrix functions. Superior conservatism reduction features are showcased by numerical simulation results
Integrating multi-virion aerosols into the Wells–Riley equation with a focus on short-range exposure
No full textWhen combining the viral load method and the Wells–Riley equation for assessing airborne infection, it remains unclear whether the approach is applicable when the inhaled aerosols contain multiple viable infectious virus particles (virions). Large droplets in short-range transmission are likely to contain multiple infectious virions. In this paper, we establish the relationship between the number of droplets within a certain range of diameter and the number of droplets containing a certain number of virions. The infection probability of an individual upon inhaling one-virion aerosols is first derived using the binomial distribution and Poisson distribution, followed by that for inhaling multi-virion aerosols using discrete compound Poisson distribution (the stuttering Poisson). A generalised Wells–Riley equation for multi-virion aerosols is then obtained using the Poisson-binomial distribution. New quanta generation formulas are obtained for both long- and short-range airborne exposure, and the existing formula in the viral load method becomes a special case of one-virion aerosols. The infectious quanta generation rate at short-range exposure due to large droplets (>30 μm diameter) is effectively the number of aerosols containing at least one infectious virion in most situations. The generalised Wells–Riley equation paves the way for understanding the infection risk posed by both short- and long-range transmission in buildings.</p
GM-ABS: Promptable Generalist Model Drives Active Barely Supervised Training in Specialist Model for 3D Medical Image Segmentation
No full textSemi-supervised learning (SSL) has greatly advanced 3D medical image segmentation by alleviating the need for intensive labeling by radiologists. While previous efforts focused on model-centric advancements, the emergence of foundational generalist models like the Segment Anything Model (SAM) is expected to reshape the SSL landscape. Although these generalists usually show performance gaps relative to previous specialists in medical imaging, they possess impressive zero-shot segmentation abilities with manual prompts. Thus, this capability could serve as 'free lunch' for training specialists, offering future SSL a promising data-centric perspective, especially revolutionizing both pseudo and expert labeling strategies to enhance the data pool. In this regard, we propose the Generalist Model-driven Active Barely Supervised (GM-ABS) learning paradigm, for developing specialized 3D segmentation models under extremely limited (barely) annotation budgets, e.g., merely cross-labeling three slices per selected scan. In specific, building upon a basic mean-teacher SSL framework, GM-ABS modernizes the SSL paradigm with two key data-centric designs: (i) Specialist-generalist collaboration, where the in-training specialist leverages class-specific positional prompts derived from class prototypes to interact with the frozen class-agnostic generalist across multiple views to achieve noisy-yet-effective label augmentation. Then, the specialist robustly assimilates the augmented knowledge via noise-tolerant collaborative learning. (ii) Expert-model collaboration that promotes active cross-labeling with notably low labeling efforts. This design progressively furnishes the specialist with informative and efficient supervision via a human-in-the-loop manner, which in turn benefits the quality of class-specific prompts. Extensive experiments on three benchmark datasets highlight the promising performance of GM-ABS over recent SSL approaches under extremely constrained labeling resources
Caries Incidence and Its Associated Factors in Hong Kong Kindergarten Children
No full textObjective: The study aimed to investigate caries incidence and its associate factors among kindergarten children in Hong Kong. Method: This 30-month prospective study recruited 3- to 4-year-old children when they started their kindergarten study. A self-administered parental questionnaire survey was used to collect the children's social demographic information and their oral health-related habits. Child's caries experience was recorded using the decayed, missing, and filled tooth (dmft) index and the visible plaque index (VPI) was used to measure their oral hygiene status. A final examination was performed after 30 months when they were in the final year of kindergarten. Data were analysed using the zero-inflated negative binomial (ZINB) regression model. Results: This study examined 660 children at baseline and 501 children at the final examination (dropout 24%). At baseline, the caries prevalence among 501 children was 23%, with mean (SD) dmft scores of 0.7 (1.8). At the final examination, caries prevalence increased to 41%, with mean (SD) dmft scores of 1.6 (2.8). The 30-month incidence rate was 34%, and the mean (SD) number of new carious teeth developed was 0.9 (1.7). Lower first molars exhibited the highest caries increment rate (11%), followed by upper second molars (9%) and upper central incisors (9%). ZINB regression analysis revealed associations among caries incidence and family income, baseline dmft, and baseline VPI (P < .05). Conclusions: One third of Hong Kong kindergarten children developed new caries. Low family income, prior caries experience and poor oral hygiene were the significant factors associated with their caries incidence. Clinical Relevance: Many children developed new caries during their kindergarten years, with their caries experience more than doubling. Preventive measures, including oral health education and reinforcing oral hygiene practice in kindergarten, are essential to reduce their caries incidence, particularly for children with low family income, caries experience and poor oral hygiene.link_to_subscribed_fulltex
A 50 s Quasiperiodic Oscillation in the Early X-Ray Afterglow of GRB 220711B
No full textIt is generally believed that long-duration gamma-ray bursts (GRBs) originate from the core collapse of rapidly spinning massive stars, and at least some of them are powered by hyperaccreting black holes (BHs). However, definite proofs about the progenitor and central engine of these GRBs have not been directly observed in the past. Here, we report the existence of a quasiperiodic oscillation (QPO) signature with periodic frequency ∼0.02 Hz in the early X-ray afterglow phase of GRB 220711B. Such a low-frequency QPO likely signals the precession of a relativistic jet launched from a GRB hyperaccreting BH central engine. The energy injection signature from the late X-ray observations (from 5 × 102 s ∼ 1 × 104 s) is consistent with the precession hypothesis. The prompt gamma-ray light curve does not show any QPO signature, suggesting that the X-ray flaring emission in the early afterglow phase and prompt emission likely originate from different accretion processess, indicating that the progenitor stars of GRBs have a core-envelope structure with a stratified angular momentum distribution and the late-time accretion disk likely has a misalignment with respect to the rotation axis of the BH. Such a misalignment is not expected in a canonical collapsar model. As a result, the QPO signature in GRB 220711B may reveal a new formation channel of long GRBs, possibly a stellar-merger-induced core collapse, with the orbital angular momentum of the binary misaligned with the spin axis of the collapsing star.link_to_subscribed_fulltex
EP240414a: Off-axis View of a Jet-cocoon System from an Expanded Progenitor Star
No full textWhen a relativistic jet is launched following the core collapse of a star, its interaction with the stellar envelope leads to the formation of a hot cocoon, which produces various viewing-angle-dependent observational phenomena following the breakout from the surface. We study the observational signatures of fast X-ray transient (FXT) EP240414a, which may originate from a jet-cocoon system viewed slightly off-axis. In our model, (1) the prompt X-ray emission lasting ∼100 s is attributed to the cooling emission from the inner cocoon (shocked jet material); (2) the ∼0.1 day X-ray emission comes from the inner cocoon’s afterglow; (3) the ∼0.4 day thermal-dominated optical emission arises from the cooling of the outer cocoon (shocked stellar material); (4) the ∼3 day nonthermal optical component and subsequent radio emission can be explained by the afterglow from a jet with a viewing angle of 10∘ ≲ θv ≲ 15∘; and (5) the associated broad-lined Type Ic supernova only dominates the optical emission after ∼7 days. Both the jet inferred from the off-axis afterglow and the inner cocoon constrained by the cooling emission are found to have similar kinetic energies, on the order of 1051 erg. We find that the progenitor’s radius is ∼3 R⊙ as constrained by the inner cocoon’s cooling emissions, indicating that the preexplosion star may be a massive helium star that is slightly inflated. More FXTs associated with off-axis jets and supernovae will be further examined by the Einstein Probe, leading to a deeper understanding of jet-cocoon systems.link_to_subscribed_fulltex
Mental health symptom profiles and temporal trends in Dutch young people's social and emotional wellbeing and suicidality, 2017–2023
No full textIntroduction: Mental health problems in young people have been increasing. Identifying profiles of several mental health symptoms, is important to better identify potential at-risk groups and tailor appropriate preventive interventions. Methods: Data was collected among 8213 young people (2017–2023) who visited the online self-help platform mindmasters.nl. Latent profile analysis classified individuals based on symptoms of substance abuse, eating disorders, psychosis, and history of suicidal thoughts and behaviours (STBs). Temporal trends in social and emotional wellbeing (Strengths and Difficulties Questionnaire (SDQ)), and in STBs were estimated for the overall study population and for each identified profile. Results: Four symptom profiles were revealed among young people: (1) relatively mentally (55.1 %); (2) young people with primarily substance use problems (7.4 %); (3) elevated severity of symptoms of psychosis, eating disorders and history of self-harm and suicidal ideation, but without history of suicide attempt (27.9 %); and (4) the highest severity of symptoms of psychosis, eating disorders, and STBs, including prior suicide attempts (9.6 %). Worsening overall temporal trends for various social and emotional wellbeing indicators were driven by specific profiles: emotional and peer problems particularly increased among individuals in Profile 2, while the increase in behavioural problems was driven by those in Profile 4. Incident suicidality increased primarily among those with previous suicide attempts. Conclusion: Overall increases over time in various social and emotional wellbeing indicators and STBs were driven by individuals with specific symptom profiles. Taking these profiles into account could improve screening for at-risk groups and foster more personalised, data-driven mental health care and prevention.link_to_subscribed_fulltex