485 research outputs found
Differential Privacy in Cooperative Multiagent Planning
Privacy-aware multiagent systems must protect agents' sensitive data while
simultaneously ensuring that agents accomplish their shared objectives. Towards
this goal, we propose a framework to privatize inter-agent communications in
cooperative multiagent decision-making problems. We study sequential
decision-making problems formulated as cooperative Markov games with
reach-avoid objectives. We apply a differential privacy mechanism to privatize
agents' communicated symbolic state trajectories, and then we analyze tradeoffs
between the strength of privacy and the team's performance. For a given level
of privacy, this tradeoff is shown to depend critically upon the total
correlation among agents' state-action processes. We synthesize policies that
are robust to privacy by reducing the value of the total correlation. Numerical
experiments demonstrate that the team's performance under these policies
decreases by only 3 percent when comparing private versus non-private
implementations of communication. By contrast, the team's performance decreases
by roughly 86 percent when using baseline policies that ignore total
correlation and only optimize team performance
Assignment maximization
We evaluate the goal of maximizing the number of individually rational assignments.
We show that it implies incentive, fairness, and implementation impossibilities.
Despite that, we present two classes of mechanisms that maximize
assignments. The first are Pareto efficient, and undominated – in terms of number
of assignments – in equilibrium. The second are fair for unassigned students and
assign weakly more students than stable mechanisms in equilibrium. We provide
comparisons with well-known mechanisms through computer simulations. Those
show that the difference in number of matched agents between the proposed mechanisms
and others in the literature is large and significant
Superporous nanocarbon materials upcycled from polyethylene terephthalate waste for scalable energy storage
Plastic pollution is becoming a universal threat affecting wildlife, marines, the atmosphere, soil, and human wellbeing. The insufficient waste management traditions, along with a growth in the "throw-away" and "single -use" culture, exacerbate the problem. Meanwhile, the fast-growing energy storage industry, such as the lithium -ion battery (LIB), requires renewable resources to provide a steady and reliable production supply chain. This work introduces a scalable industrial mature route to transform polyethylene terephthalate (PET) plastic waste into a superporous activated carbon material for rechargeable LIBs. We characterized the analytical properties of the waste-derived carbon material and used it to develop LIB anodes. Then, we generated carbon-silicon com-posite anodes by impregnating silicon nanoparticles (SiNPs) into the superporous connected architecture network. We conducted density functional-based tight-binding (DFTB+) quantum chemical calculations to elucidate the binding interactions between PET and SiNPs. By implementing electrochemical impedance spec-troscopy (EIS), galvanostatic intermittent titration technique (GITT), and differential capacity analysis (DCA), we investigated the root causes of the degradation mechanisms of the material. Finally, our techno-economical study highlights the merits of a sustainable approach for transferring waste materials into valuable products such as energy storage. This work can create further research and development for recycling plastic wastes towards scalable stationary battery storage with the benefits of environmental sustainability and circular economics
Characterizing Multiscale Mechanical Properties of Brain Tissue Using Atomic Force Microscopy, Impact Indentation, and Rheometry
To design and engineer materials inspired by the properties of the brain, whether for mechanical simulants or for tissue regeneration studies, the brain tissue itself must be well characterized at various length and time scales. Like many biological tissues, brain tissue exhibits a complex, hierarchical structure. However, in contrast to most other tissues, brain is of very low mechanical stiffness, with Young's elastic moduli E on the order of 100s of Pa. This low stiffness can present challenges to experimental characterization of key mechanical properties. Here, we demonstrate several mechanical characterization techniques that have been adapted to measure the elastic and viscoelastic properties of hydrated, compliant biological materials such as brain tissue, at different length scales and loading rates. At the microscale, we conduct creep-compliance and force relaxation experiments using atomic force microscope-enabled indentation. At the mesoscale, we perform impact indentation experiments using a pendulum-based instrumented indenter. At the macroscale, we conduct parallel plate rheometry to quantify the frequency dependent shear elastic moduli. We also discuss the challenges and limitations associated with each method. Together these techniques enable an in-depth mechanical characterization of brain tissue that can be used to better understand the structure of brain and to engineer bio-inspired materials
Oleoylethanolamine and palmitoylethanolamine modulate intestinal permeability in vitro via TRPV1 and PPARα
Cannabinoids modulate intestinal permeability through cannabinoid receptor 1 (CB1). The endocannabinoid-like compounds oleoylethanolamine (OEA) and palmitoylethanolamine (PEA) play an important role in digestive regulation, and we hypothesized they would also modulate intestinal permeability. Transepithelial electrical resistance (TEER) was measured in human Caco-2 cells to assess permeability after application of OEA and PEA and relevant antagonists. Cells treated with OEA and PEA were stained for cytoskeletal F-actin changes and lysed for immunoassay. OEA and PEA were measured by liquid chromatography–tandem mass spectrometry. OEA (applied apically, logEC50 −5.4) and PEA (basolaterally, logEC50 −4.9; apically logEC50 −5.3) increased Caco-2 resistance by 20–30% via transient receptor potential vanilloid (TRPV)-1 and peroxisome proliferator-activated receptor (PPAR)-α. Preventing their degradation (by inhibiting fatty acid amide hydrolase) enhanced the effects of OEA and PEA. OEA and PEA induced cytoskeletal changes and activated focal adhesion kinase and ERKs 1/2, and decreased Src kinases and aquaporins 3 and 4. In Caco-2 cells treated with IFNγ and TNFα, OEA (via TRPV1) and PEA (via PPARα) prevented or reversed the cytokine-induced increased permeability compared to vehicle (0.1% ethanol). PEA (basolateral) also reversed increased permeability when added 48 or 72 h after cytokines (P < 0.001, via PPARα). Cellular and secreted levels of OEA and PEA (P < 0.001–0.001) were increased in response to inflammatory mediators. OEA and PEA have endogenous roles and potential therapeutic applications in conditions of intestinal hyperpermeability and inflammation
Shifted phase of EEG cross-frequency coupling in individuals with Phelan-McDermid syndrome
Background
Phelan-McDermid Syndrome (PMS) is a rare condition caused by deletion or mutation of the SHANK3 gene. Individuals with PMS frequently present with intellectual disability, autism spectrum disorder, and other neurodevelopmental challenges. Electroencephalography (EEG) can provide a window into network-level function in PMS.
Methods
Here, we analyze EEG data collected across multiple sites in individuals with PMS (n = 26) and typically developing individuals (n = 15). We quantify oscillatory power, alpha-gamma phase-amplitude coupling strength, and phase bias, a measure of the phase of cross frequency coupling thought to reflect the balance of feedforward (bottom-up) and feedback (top-down) activity.
Results
We find individuals with PMS display increased alpha-gamma phase bias (U = 3.841, p < 0.0005), predominantly over posterior electrodes. Most individuals with PMS demonstrate positive overall phase bias while most typically developing individuals demonstrate negative overall phase bias. Among individuals with PMS, strength of alpha-gamma phase-amplitude coupling was associated with Sameness, Ritualistic, and Compulsive behaviors as measured by the Repetitive Behavior Scales-Revised (Beta = 0.545, p = 0.011).
Conclusions
Increased phase bias suggests potential circuit-level mechanisms underlying phenotype in PMS, offering opportunities for back-translation of findings into animal models and targeting in clinical trials
Effect of maternal administration of betamethasone on peripheral arterial development in fetal rabbit lungs
Objectives: Glucocorticoids promote lung maturation and reduce the incidence of respiratory distress syndrome in premature newborns. We hypothesized that betamethasone (BM), which is known to induce thinning of the alveolar walls, would also thin the arterial media and adventitia of intra-parenchymatic vessels in developing rabbit lungs. Study Design: 112 fetuses from 21 time-mated, pregnant, giant white rabbits received maternal injections of BM at either 0.05 or 0.1 mg/kg/day on days 25-26 of gestational age. Controls received either saline (10 does, 56 fetuses) or no injection (10 does, 59 fetuses). Fetuses were harvested from day 27 onwards until term (day 31). 44 additional fetuses (8 does) were harvested between days 23 and 26. Endpoints were wet lung-to-body weight ratio, vascular morphometric indices and immunohistochemistry staining for α-smooth muscle actin, Flk-1, vascular endothelial growth factor (VEGF) and endothelial nitric oxide synthase (eNOS). ANOVA (Tukey's test) and independent t test (p < 0.05) were used for comparison between BM and saline groups. Results: Maternal BM injected on days 25-26 to pregnant rabbits induced a significant decrease in fetal body and lung weight and the lung-to-body weight ratio in the preterm pups shortly after injection. BM led to a dose-dependent thinning of the arterial media and adventitia (pulmonary arteries with an external diameter (ED) of <100 μm), to an increase in the percentage of non-muscularized peripheral vessels (ED <60 μm), in eNOS and VEGF immunoreactivity of the endothelial and smooth muscle cells in the pulmonary vessels and to an increase in Flk-1-positive pulmonary epithelial cell density. Conclusions: Maternal administration of BM caused thinning of the arterial wall of pulmonary vessels (ED <100 μm) and a decrease in muscularization in peripheral vessels (ED <60 μm). This coincided with increased expression of Flk-1 in the endothelium and smooth muscle cells of the pulmonary arteries. All the effects studied were dose-dependent. Copyrigh
PaLI-X: On Scaling up a Multilingual Vision and Language Model
We present the training recipe and results of scaling up PaLI-X, a
multilingual vision and language model, both in terms of size of the components
and the breadth of its training task mixture. Our model achieves new levels of
performance on a wide-range of varied and complex tasks, including multiple
image-based captioning and question-answering tasks, image-based document
understanding and few-shot (in-context) learning, as well as object detection,
video question answering, and video captioning. PaLI-X advances the
state-of-the-art on most vision-and-language benchmarks considered (25+ of
them). Finally, we observe emerging capabilities, such as complex counting and
multilingual object detection, tasks that are not explicitly in the training
mix
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