76 research outputs found
BENO: Boundary-embedded Neural Operators for Elliptic PDEs
Elliptic partial differential equations (PDEs) are a major class of
time-independent PDEs that play a key role in many scientific and engineering
domains such as fluid dynamics, plasma physics, and solid mechanics. Recently,
neural operators have emerged as a promising technique to solve elliptic PDEs
more efficiently by directly mapping the input to solutions. However, existing
networks typically cannot handle complex geometries and inhomogeneous boundary
values present in the real world. Here we introduce Boundary-Embedded Neural
Operators (BENO), a novel neural operator architecture that embeds the complex
geometries and inhomogeneous boundary values into the solving of elliptic PDEs.
Inspired by classical Green's function, BENO consists of two branches of Graph
Neural Networks (GNNs) for interior source term and boundary values,
respectively. Furthermore, a Transformer encoder maps the global boundary
geometry into a latent vector which influences each message passing layer of
the GNNs. We test our model extensively in elliptic PDEs with various boundary
conditions. We show that all existing baseline methods fail to learn the
solution operator. In contrast, our model, endowed with boundary-embedded
architecture, outperforms state-of-the-art neural operators and strong
baselines by an average of 60.96\%. Our source code can be found
https://github.com/AI4Science-WestlakeU/beno.git.Comment: Accepted by ICLR 202
Corn silk polysaccharide ameliorates high fat diet induced hepatic steatosis in mice
To study the therapeutic effect of corn silk polysaccharide (CSP) on NAFLD mice induced by high fat diet. C57BL/6J mice were divided into normal control group (NC), high fat diet (HFD) group, HFD+200 mg/kg CSP group, and HFD+600 mg/kg CSP group. NAFLD mouse model was established by HFD feeding. Blood and liver tissues of each group were collected and biochemical and pathological tests were performed. The energy intake of NAFLD model group was higher than that of normal control group, and the food intake, water intake, and excretion of NAFLD model group were lower than that of normal control group. There was no statistical significance in the food intake, energy intake, water intake, and excretion of CSP group compared with that of NAFLD model group, nor was there any statistical significance between CSP and two doses of CSP. Biochemical tests showed that CSP decreased the levels of alanine aminotransferase, aspartate aminotransferase, triglyceride and total cholesterol in serum of HFDfed mice, and inhibited the expressions of IL-6 and TNF-α in liver tissue. Pathological results showed that CSP improved HFD-induced hepatic steatosis
How Well Does GPT-4V(ision) Adapt to Distribution Shifts? A Preliminary Investigation
In machine learning, generalization against distribution shifts -- where
deployment conditions diverge from the training scenarios -- is crucial,
particularly in fields like climate modeling, biomedicine, and autonomous
driving. The emergence of foundation models, distinguished by their extensive
pretraining and task versatility, has led to an increased interest in their
adaptability to distribution shifts. GPT-4V(ision) acts as the most advanced
publicly accessible multimodal foundation model, with extensive applications
across various domains, including anomaly detection, video understanding, image
generation, and medical diagnosis. However, its robustness against data
distributions remains largely underexplored. Addressing this gap, this study
rigorously evaluates GPT-4V's adaptability and generalization capabilities in
dynamic environments, benchmarking against prominent models like CLIP, LLaVA,
and Gemini. We delve into GPT-4V's zero-shot generalization across 13 diverse
datasets spanning natural, medical, and molecular domains. We further
investigate its adaptability to controlled data perturbations and examine the
efficacy of in-context learning as a tool to enhance its adaptation. Our
findings delineate GPT-4V's capability boundaries in distribution shifts,
shedding light on its strengths and limitations across various scenarios.
Importantly, this investigation contributes to our understanding of how AI
foundation models generalize to distribution shifts, offering pivotal insights
into their adaptability and robustness. The code is publicly available at
https://github.com/jameszhou-gl/gpt-4v-distribution-shift.Comment: added the investigation of Gemini. 66 pages, 41 figure
Vapor-Driven Propulsion of Catalytic Micromotors
Chemically-powered micromotors offer exciting opportunities in diverse fields, including therapeutic delivery, environmental remediation, and nanoscale manufacturing. However, these nanovehicles require direct addition of high concentration of chemical fuel to the motor solution for their propulsion. We report the efficient vapor-powered propulsion of catalytic micromotors without direct addition of fuel to the micromotor solution. Diffusion of hydrazine vapor from the surrounding atmosphere into the sample solution is instead used to trigger rapid movement of iridium-gold Janus microsphere motors. Such operation creates a new type of remotely-triggered and powered catalytic micro/nanomotors that are responsive to their surrounding environment. This new propulsion mechanism is accompanied by unique phenomena, such as the distinct off-on response to the presence of fuel in the surrounding atmosphere, and spatio-temporal dependence of the motor speed borne out of the concentration gradient evolution within the motor solution. The relationship between the motor speed and the variables affecting the fuel concentration distribution is examined using a theoretical model for hydrazine transport, which is in turn used to explain the observed phenomena. The vapor-powered catalytic micro/nanomotors offer new opportunities in gas sensing, threat detection, and environmental monitoring, and open the door for a new class of environmentally-triggered micromotors
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Turning Erythrocytes into Functional Micromotors
Attempts to apply artificial nano/micromotors for diverse biomedical applications have inspired a variety of strategies for designing motors with diverse propulsion mechanisms and functions. However, existing artificial motors are made exclusively of synthetic materials, which are subject to serious immune attack and clearance upon entering the bloodstream. Herein we report an elegant approach that turns natural red blood cells (RBCs) into functional micromotors with the aid of ultrasound propulsion and magnetic guidance. Iron oxide nanoparticles are loaded into the RBCs, where their asymmetric distribution within the cells results in a net magnetization, thus enabling magnetic alignment and guidance under acoustic propulsion. The RBC motors display efficient guided and prolonged propulsion in various biological fluids, including undiluted whole blood. The stability and functionality of the RBC motors, as well as the tolerability of regular RBCs to the ultrasound operation, are carefully examined. Since the RBC motors preserve the biological and structural features of regular RBCs, these motors possess a wide range of antigenic, transport, and mechanical properties that common synthetic motors cannot achieve and thus hold considerable promise for a number of practical biomedical uses
Materials systems and autonomy in electromechanical sound art
Sound art is a difficult to categorise and broad genre description that draws together modes of creative practice which use sound as a medium or a subject. The field is considered to be critically underrepresented and under-theorised despite an increase of attention and popularity since the 1990s (Licht 2007, 2001, Cox 2009). This is partly as a consequence of an analytical and historical emphasis on textual and conceptual approaches which dominated the arts through the 1970s and 1980s (Cox 2011, 2013). In particular, acknowledgement of the influence of object-based and kinetic sculpture within the field of sound art is found to be inadequate (Chau 2014, Keylin 2015).
This thesis presents an original body of sound art practice as a means through which to uncover and explore connections between sound art, experimental composition, kinetic art and sculpture. The term 'electromechanical' is used to identify this work, highlighting its particular concerns with the use of electrically animated or amplified materials. Through the production, exhibition, critical appraisal and contextualisation of the work new observations and distinctions within the field are presented. These include the identification of a 'closed system aesthetic' and the distinction between robotic and process driven approaches to electromechanical sound art. A further contribution to the field consists of a detailed consideration of sound art emerging from an intersection of experimental music and sculptural practices during the 1960s.
The original works produced for the project, and their production are documented and described in detail alongside existing canonical and contemporary examples of sound art. Analysis of these works is informed by materialist and object-orientated critical positions, and science and technology studies. The method of art practice as research is described and extended in an original way that encompasses and applies a systems approach to creative practice
Vapor-Driven Propulsion of Catalytic Micromotors
Chemically-powered micromotors offer exciting opportunities in diverse fields, including therapeutic delivery, environmental remediation, and nanoscale manufacturing. However, these nanovehicles require direct addition of high concentration of chemical fuel to the motor solution for their propulsion. We report the efficient vapor-powered propulsion of catalytic micromotors without direct addition of fuel to the micromotor solution. Diffusion of hydrazine vapor from the surrounding atmosphere into the sample solution is instead used to trigger rapid movement of iridium-gold Janus microsphere motors. Such operation creates a new type of remotely-triggered and powered catalytic micro/nanomotors that are responsive to their surrounding environment. This new propulsion mechanism is accompanied by unique phenomena, such as the distinct off-on response to the presence of fuel in the surrounding atmosphere, and spatio-temporal dependence of the motor speed borne out of the concentration gradient evolution within the motor solution. The relationship between the motor speed and the variables affecting the fuel concentration distribution is examined using a theoretical model for hydrazine transport, which is in turn used to explain the observed phenomena. The vapor-powered catalytic micro/nanomotors offer new opportunities in gas sensing, threat detection, and environmental monitoring, and open the door for a new class of environmentally-triggered micromotors
Cell-Membrane-Coated Synthetic Nanomotors for Effective Biodetoxification
A red blood cell membrane-camouflaged nanowire that can serve as new generation of biomimetic motor sponge is described. The biomimetic motor sponge is constructed by the fusion of biocompatible gold nanowire motors and RBC nanovesicles. The motor sponge possesses a high coverage of RBC vesicles, which remain totally functional due to its exclusively oriented extracellular functional portion on the surfaces of motor sponge. These biomimetic motors display efficient acoustical propulsion, including controlled movement in undiluted whole blood. The RBC vesicles on the motor sponge remain highly stable during the propulsion process, conferring thus the ability to absorb membrane-damaging toxins and allowing the motor sponge to be used as efficient toxin decoys. The efficient propulsion of the motor sponges under an ultrasound field results in accelerated neutralization of the membrane-damaging toxins. Such motor sponges connect artificial nanomotors with biological entities and hold great promise for treating a variety of injuries and diseases caused by membrane-damaging toxins
Cell-Membrane-Coated Synthetic Nanomotors for Effective Biodetoxification
A red blood cell membrane-camouflaged nanowire that can serve as new generation of biomimetic motor sponge is described. The biomimetic motor sponge is constructed by the fusion of biocompatible gold nanowire motors and RBC nanovesicles. The motor sponge possesses a high coverage of RBC vesicles, which remain totally functional due to its exclusively oriented extracellular functional portion on the surfaces of motor sponge. These biomimetic motors display efficient acoustical propulsion, including controlled movement in undiluted whole blood. The RBC vesicles on the motor sponge remain highly stable during the propulsion process, conferring thus the ability to absorb membrane-damaging toxins and allowing the motor sponge to be used as efficient toxin decoys. The efficient propulsion of the motor sponges under an ultrasound field results in accelerated neutralization of the membrane-damaging toxins. Such motor sponges connect artificial nanomotors with biological entities and hold great promise for treating a variety of injuries and diseases caused by membrane-damaging toxins
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