360 research outputs found
A Protocol for Coupling Volumetrically Dynamic In vitro Experiments to Numerical Physiology Simulation for A Hybrid Cardiovascular Model
Objective: The Physiology Simulation Coupled Experiment (PSCOPE) is a hybrid modeling framework that enables a physical fluid experiment to operate in the context of a closed-loop computational simulation of cardiovascular physiology. Previous PSCOPE methods coupled rigid experiments to a lumped parameter network (LPN) of physiology but are incompatible with volumetrically dynamic experiments where fluid volume varies periodically. We address this limitation by introducing a method capable of coupling rigid, multi-branch, and volumetrically dynamic in-vitro experiments to an LPN. Methods: Our proposed method utilizes an iterative weighted-averaging algorithm to identify the unique solution waveforms for a given PSCOPE model. We confirm the accuracy of these PSCOPE solutions by integrating mathematical surrogates of in vitro experiments directly into the LPN to derive reference solutions, which serve as the gold standard to validate the solutions obtained from using our proposed method to couple the same mathematical surrogates to the LPN. Finally, we illustrate a practical application of our PSCOPE method by coupling an in-vitro renal circulation experiment to the LPN. Results: Compared to the reference solution, the normalized root mean square error of the flow and pressure waveforms were 0.001%∼0.55%, demonstrating the accuracy of the coupling method. Conclusion: We successfully coupled the in-vitro experiment to the LPN, demonstrating the real-world performance within the constraints of sensor and actuation limitations in the physical experiment. Significance: This study introduces a PSCOPE method that can be used to investigate medical devices and anatomies that exhibit periodic volume changes, expanding the utility of the hybrid framework
Heat Transport with a Twist
Despite the desirability of polymers for use in many products due to their
flexibility, light weight, and durability, their status as thermal insulators
has precluded their use in applications where thermal conductors are required.
However, recent results suggest that the thermal conductance of polymers can be
enhanced and that their heat transport behaviors may be highly sensitive to
nanoscale control. Here we use non-equilibrium molecular dynamics (MD)
simulations to study the effect of mechanical twist on the steady-state thermal
conductance across multi-stranded polyethylene wires. We find that a highly
twisted double-helical polyethylene wire can display a thermal conductance up
to three times that of its untwisted form, an effect which can be attributed to
a structural transition in the strands of the double helix. We also find that
in thicker wires composed of many parallel strands, adding just one twist can
increase its thermal conductance by over 30%. However, we find that unlike
stretching a polymer wire, which causes a monotonic increase in thermal
conductance, the effect of twist is highly non-monotonic, and certain amounts
of twist can actually decrease the thermal conductance. Finally, we apply the
Continuous Chirality Measure (CCM) in an attempt to explore the correlation
between heat conductance and chirality. The CCM is found to correlate with
twist as expected, but we attribute the observed heat transport behaviors to
structural factors other than chirality
Safety-Critical Ergodic Exploration in Cluttered Environments via Control Barrier Functions
In this paper, we address the problem of safe trajectory planning for
autonomous search and exploration in constrained, cluttered environments.
Guaranteeing safe navigation is a challenging problem that has garnered
significant attention. This work contributes a method that generates guaranteed
safety-critical search trajectories in a cluttered environment. Our approach
integrates safety-critical constraints using discrete control barrier functions
(DCBFs) with ergodic trajectory optimization to enable safe exploration.
Ergodic trajectory optimization plans continuous exploratory trajectories that
guarantee full coverage of a space. We demonstrate through simulated and
experimental results on a drone that our approach is able to generate
trajectories that enable safe and effective exploration. Furthermore, we show
the efficacy of our approach for safe exploration of real-world single- and
multi- drone platforms
Reconstruction of Age Distributions from Differentially Private Census data
The age distribution of a population is important for understanding the demand and provision of labor and services, and as a denominator for calculating key agespecific rates such as fertility and mortality. In the US, the most important source of information on age distributions is the decennial census, but a new disclosure avoidance system (DAS) based on differential privacy will inject noise into the data, potentially compromising its utility for small areas and minority populations. In this paper, we explore the question whether there are statistical methods that can be applied to noisy age distributions to enhance the research uses of census data without compromising privacy. We apply a non-parametric method for smoothing with naive or informative priors to age distributions from the 2010 Census via demonstration data which have had the US Census Bureau’s implementation of differential privacy applied. We find that smoothing age distributions can increase the fidelity of the demonstration data to previously published population counts by age. We discuss implications for uses of data from the 2020 US Census and potential consequences for the measurement of population dynamics, health, and disparities
Strengthening Personal Data Protection, Cyber Security, and Improving Public Awareness in Indonesia: Progressive Legal Perspective
The development of technology, communication, and the internet has positive and negative influences on all sectors of life in society. One of the negative impacts and problems is the alleged criminal act of buying and selling data and the absence of a special law (lex specialist) regarding the regulation of Indonesian personal data. The purpose of this research is to analyze in-depth the efforts to strengthen the protection of personal data, cyber security, and increase public awareness of the perspective of Progressive Law in Indonesia. This study uses a normative juridical method using secondary data, a statutory approach, a conceptual approach, and a case approach. This scientific paper concludes that the Synergy of Ministries and related institutions (Legislative, Executive, and Judiciary) is the key to protecting personal data and cyber resilience. Then, strengthening efforts should be made, namely immediately passing the Draft Law on Personal Data Protection (RUU PDP), forming an independent institution. However, if at this time a dispute occurs, it can be resolved by Article 30 of the ITE Law and the PMH Lawsuit (Tort), supported by a progressive legal approach and futuristic interpretation by the judge examining the quo case. The synergy of government agencies, the private sector, and other stakeholders is needed to increase public awareness by increasing education/dissemination of efforts to prevent misuse of personal data
Allometry of sodium requirements and mineral lick use among herbivorous mammals
Sodium (Na) plays a critical role in the functioning of terrestrial ecosystems. In Na-poor regions, plant consumers may experience Na deficiency and adapt by seeking supplementary Na resources. This can markedly impact animal behavior, space-use, and co-existence, with concomitant impacts on ecosystems. Many studies have noted that Na-seeking behaviors, such as soil consumption from mineral licks, are predominately observed for larger-bodied herbivores. However, the mechanisms that drive interspecific variation in Na deficiency and mineral lick use remain poorly understood. Here, we examine whether allometric scaling of Na requirements can explain variation in mineral lick use by herbivorous and omnivorous mammals. We 1) collated data from published literature to derive an allometric scaling of Na requirements in mammals, 2) compared predicted Na requirements to estimated Na intake of mammal communities in three globally distant sites: the Peruvian Amazon, Kalahari Desert, and Malaysian Borneo and 3) examined the relationship between predicted Na deficiency and mineral lick use utilizing camera-trap and mammal abundance data at each site. We found that minimum daily Na maintenance requirements in mammals scaled allometrically at a higher factor (BM0.91 (CI: 0.80–1.0)) than that of food and water Na intake (BM0.71–0.79), indicating that larger species may be more susceptible to Na limitation. This aligned with a positive association between mineral lick use and body mass (BM), as well as Na deficiency, by species at all sites, and increased artificial salt and mineral lick consumption by larger-bodied mammals in the Kalahari. Our results suggest that larger herbivores may be more sensitive to anthropogenic impacts to Na availability, which may alter their functional roles in ecosystems, particularly in Na-poor regions. Further research is needed to explore the consequences of changing Na availability on animals and ecosystems, as well as advance our understanding of Na physiology in mammals
Anthropogenic supply of nutrients in a wildlife reserve may compromise conservation success
In nutrient-poor wildlife reserves it has become common-practice to provide supplemental mineral resources for wildlife. Yet, the impacts of anthropogenic mineral supplementation on large herbivore nutrition, behaviour, and subsequent impact on ecosystem processes have received little attention. Here, we examine the contribution of anthropogenic mineral lick provision to wildlife nutrient intake across a community of mammalian herbivores (>10 kg) in the southern Kalahari Desert. Based on predicted daily nutrient intake and a faecal nutrient assessment, many large herbivore species appear deficient in phosphorus (P), sodium (Na), or zinc (Zn). For these nutrients, anthropogenic salt and mineral licks constitute an important source of nutrient intake helping to reduce or overcome requirement deficits. Larger-bodied species disproportionately consumed licks, acquiring more nutritional benefits. A comprehensive assessment of animal body condition indicated that, in general, large herbivores display good health. However, bulk grazers, non-ruminants and females displayed poorer body condition. We discuss how provisioning of anthropogenic mineral licks may inflate large herbivore populations beyond the long-term carrying capacity of the reserve by decoupling wildlife fecundity from nutrient-related feedbacks on population growth. Over time, this could compromise ecosystem integrity through habitat degradation, modified species interactions and trophic cascades. Based on results presented here, it is clear that anthropogenic provisioning of mineral licks should be considered cautiously by wildlife managers aiming to conserve natural processes in landscapes
Occupational Histories of Cancer Patients in a Canadian Cancer Treatment Centre and the Generated Hypothesis Regarding Breast Cancer and Farming
Occupational exposures increase cancer risks. The Windsor Regional Cancer Centre in Windsor, Ontario, was the first Canadian cancer treatment center to collect the work histories of its patients, which were recorded using a computer-based questionnaire. Breast cancer cases represented the largest respondent group. The lifetime occupational histories of 299 women with newly diagnosed breast cancers were compared with those of 237 women with other cancers. Odds ratios (ORs) were calculated using logistic regression, adjusting for age, social class, and education. The OR for women £ 55 years of age with breast cancer who had ever farmed, compared with women of the same age with other cancers, was 9.05 (95% CI 1.06, 77.43). Patients’ occupational histories can help to inform understanding of cancer etiology and prevention. This effort points to a need for investigation of the possible association between breast cancer and agricultural hazards such as pesticides
Cancer and Construction: What Occupational Histories in a Canadian Community Reveal
From 2000 to 2002, male patients at a Canadian cancer treatment center with new-incident head-and-neck or esophageal cancers were invited to participate in a population-based study. The study population included 87 cases and 172 controls. A lifetime-history questionnaire was administered. Odds ratios (ORs) were calculated for occupational groups with a minimum of five cases, adjusted for duration of employment, age, smoking, alcohol, education, and income. A significantly increased risk was shown for construction workers (OR = 2.20; 95% CI 1.25–3.91). This investigation of a set of rare cancers over a limited time period demonstrates the feasibility of this research approach. The increased risk among construction workers supports the need for more comprehensive study of exposures in this occupational group
Reconstructing the Mind's Eye: fMRI-to-Image with Contrastive Learning and Diffusion Priors
We present MindEye, a novel fMRI-to-image approach to retrieve and
reconstruct viewed images from brain activity. Our model comprises two parallel
submodules that are specialized for retrieval (using contrastive learning) and
reconstruction (using a diffusion prior). MindEye can map fMRI brain activity
to any high dimensional multimodal latent space, like CLIP image space,
enabling image reconstruction using generative models that accept embeddings
from this latent space. We comprehensively compare our approach with other
existing methods, using both qualitative side-by-side comparisons and
quantitative evaluations, and show that MindEye achieves state-of-the-art
performance in both reconstruction and retrieval tasks. In particular, MindEye
can retrieve the exact original image even among highly similar candidates
indicating that its brain embeddings retain fine-grained image-specific
information. This allows us to accurately retrieve images even from large-scale
databases like LAION-5B. We demonstrate through ablations that MindEye's
performance improvements over previous methods result from specialized
submodules for retrieval and reconstruction, improved training techniques, and
training models with orders of magnitude more parameters. Furthermore, we show
that MindEye can better preserve low-level image features in the
reconstructions by using img2img, with outputs from a separate autoencoder. All
code is available on GitHub.Comment: Project Page at https://medarc-ai.github.io/mindeye-website/. Code at
https://github.com/MedARC-AI/fMRI-reconstruction-NSD
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