34,645 research outputs found
Small deviations of iterated processes in space of trajectories
We derive logarithmic asymptotics of probabilities of small deviations for
iterated processes in the space of trajectories. We find conditions under which
these asymptotics coincide with those of processes generating iterated
processes. When these conditions fail the asymptotics are quite different
Algorithmic statistics revisited
The mission of statistics is to provide adequate statistical hypotheses
(models) for observed data. But what is an "adequate" model? To answer this
question, one needs to use the notions of algorithmic information theory. It
turns out that for every data string one can naturally define
"stochasticity profile", a curve that represents a trade-off between complexity
of a model and its adequacy. This curve has four different equivalent
definitions in terms of (1)~randomness deficiency, (2)~minimal description
length, (3)~position in the lists of simple strings and (4)~Kolmogorov
complexity with decompression time bounded by busy beaver function. We present
a survey of the corresponding definitions and results relating them to each
other
A Narrative Review of In-Textile Sensors in Human Health Applications
Sensors have become more versatile and sophisticated in recent years to fulfill the increasing demands for human health applications. Physiological information such as electrocardiogram, pulse rate, and respiration are essential indications of personal health, often collected as vitals, which are typically collected from medical-grade electrocardiogram (ECG) machines. In-textile sensors are a fast-growing sub-category of wearable sensors embedded in smart textiles to acquire physiological information and movement index and provide harmful chemical warnings without compromising the comfortable nature of clothing. Recent literature has shown that integrating new materials has greatly improved the stability, specificity, and selectivity of in-textile sensors. For example, polyvinylidene fluoride nanofiber produced a highly stretchable sensor to measure ECG readings during movement without losing data quality. This review discusses a group of nanomaterial-based in-textile sensors for consumer use in the home, workplace, and healthcare environments. This review will focus on exploring and analyzing the latest developments in these nanomaterial-based e-textiles due to their ability to be more easily integrated for daily use and their great potential for medical applications. Future work will be necessary to incorporate recycled materials, improve the method of powering these sensors, and ultimately refine the designs to be appropriate for more sustainable use
Three-dimensional dynamic fracture analysis using scaled boundary finite element method: A time-domain method
A time-domain method for modeling three-dimensional transient dynamic fracture problems is developed based on the scaled boundary finite element method (SBFEM). For this purpose, a cracked polyhedron modeled by the SBFEM is constructed to simulate the through-thickness crack in the domain. The mass and stiffness matrices of polyhedrons are derived and assembled to form the three-dimensional elastodynamic equations in the time domain. High-order elements are used to improve computational accuracy. The dynamic response is evaluated by the Newmark method, and the stress field is expressed semi-analytically. Based on the theory of linear ealstodynamic fracture mechanics, the static stress intensity factors are extended to the dynamic stress intensity factors (DSIFs) by considering the dynamic effect. The DSIFs are directly extracted from the analytical solution in the radial direction of the cracked polyhedron. Numerical examples are modeled to validate the presented method. Good agreement is observed between the computed results and the published results in the literature. The effects of the time step, mesh density, and material damping coefficient on the computational accuracy are also investigated. It is found that moderately sized third-order elements can lead to very good solutions, and an increase of both the orders or number of elements does not significantly improve the accuracy of the simulation. The distribution of the DSIFs along the crack front of the 3D models is investigated and it is found that the DSIFs vary strongly along the crack front
Antigenotoxicity and antioxidant activities of bitter leaf (Vernonia amygdalina Del.) accessions from different parts of Nigeria
Bitter leaf (Vernonia amygdalina Del.) plant is a tree species that is highly cultivated in Nigeria for its nutritive and therapeutic values. This study aimed to determine the antioxidant and antigenotoxicity effects (in vitro) of 52 accessions of V. amygdalina collected from six geopolitical zones of Nigeria (North East, North West, North Central, South South, East and West) by evaluating the 2,2-diphenyl-1-picrylhydrazyl (DPPH) and nitric oxide (NO-) scavenging antioxidant activities, flavonoid and phenolic contents as well as ethidium bromide-induced DNA (deoxyribonucleic acid) damage of bitter leaf. The results showed that accessions MN628016 (Oshimili South, Delta State) and MN628010 (Akoko Edo, Edo State), respectively had higher amounts of flavonoid (287.19 mg/g/FW) and phenolic (307.90 mg/g/FW) contents. The accessions MN627984 (Ikpoba Okha, Edo State) and MN627975 (Owerri, Imo State) had the highest nitric oxide (85.73%) and DPPH radical scavenging inhibitory effect (98.92%). The highest percentage fragmented DNA (45.05%), was observed in Allium cepa roots homogenised and mixed with ethidium bromide followed by the A. cepa roots homogenised and mixed with the leaf extract of V. amygdalina accession MN627977 (36.12%). However, V. amygdalina accessions MN628008 (457.62%, Warri North, Delta State) had the highest percentage increase of fragmented DNA followed by MN628024 (395.04%, Oshimili North, Delta State), MN628015 (345.54%; Aniocha North, Delta State) and MN627984 (342.04%; Ikpoba Okha, Edo State) while accession MN628010 (7.32%; Akoko Edo, Edo State) had the lowest. Accession MN628010 which possessed the highest amount of phenolic content had the lowest percentage increase of fragmented DNA and accession MN627984 which possessed the highest nitric oxide radical scavenging inhibitory effect was among the accessions with the highest percentage increase of fragmented DNA. The findings of this study suggest that the observed lowest percentage of fragmented DNA of A. cepa roots growth induced with the solution of ethidium bromide and treated with V. amygdalina accessions MN628010 extracts (antigenotoxic) could be as a result of the high antioxidant activities in the V. amygdalina accessions. In summary, the findings of this study showed that the 52 V. amygdalina accessions obtained from different locations of Nigeria will help to combat ethidium bromide induced genoxicities and any other genotoxicant that may lead to different complications in plant (A. cepa roots), as all the accessions possessed antioxidant and antigenotoxic properties, as such, possessed comparable amount of natural antioxidant activities and antigenotoxicity
Neural Networks With Motivation
Animals rely on internal motivational states to make decisions. The role of motivational salience in decision making is in early stages of mathematical understanding. Here, we propose a reinforcement learning framework that relies on neural networks to learn optimal ongoing behavior for dynamically changing motivation values. First, we show that neural networks implementing Q-learning with motivational salience can navigate in environment with dynamic rewards without adjustments in synaptic strengths when the needs of an agent shift. In this setting, our networks may display elements of addictive behaviors. Second, we use a similar framework in hierarchical manager-agent system to implement a reinforcement learning algorithm with motivation that both infers motivational states and behaves. Finally, we show that, when trained in the Pavlovian conditioning setting, the responses of the neurons in our model resemble previously published neuronal recordings in the ventral pallidum, a basal ganglia structure involved in motivated behaviors. We conclude that motivation allows Q-learning networks to quickly adapt their behavior to conditions when expected reward is modulated by agent’s dynamic needs. Our approach addresses the algorithmic rationale of motivation and makes a step toward better interpretability of behavioral data via inference of motivational dynamics in the brain
Stellar Coronal and Wind Models: Impact on Exoplanets
Surface magnetism is believed to be the main driver of coronal heating and
stellar wind acceleration. Coronae are believed to be formed by plasma confined
in closed magnetic coronal loops of the stars, with winds mainly originating in
open magnetic field line regions. In this Chapter, we review some basic
properties of stellar coronae and winds and present some existing models. In
the last part of this Chapter, we discuss the effects of coronal winds on
exoplanets.Comment: Chapter published in the "Handbook of Exoplanets", Editors in Chief:
Juan Antonio Belmonte and Hans Deeg, Section Editor: Nuccio Lanza. Springer
Reference Work
Male Infertility and Future Cardiometabolic Health: Does the Association Vary by Sociodemographic Factors?
Objective:
To determine whether the association between male infertility and incident cardiometabolic disease is modified by socioeconomics, race, or geographic region.
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Materials and Method:
Retrospective review of data from insurance claims from Optum's de-identified Clinformatics Data Mart Database. Subjects were men, 18-50 years old, with an associated diagnosis of infertility in the United States between 2003 and 2016. Analytical sample were men captured by the Optum's de-identified Clinformatics Data Mart Database with an associated diagnosis of infertility. Men were classified as either infertile, or not, based on diagnosis or procedural codes. Cardiometabolic health outcomes were then assessed using current procedural terminology codes for diabetes, hypertension, hyperlipidemia, and heart disease. Confounding factors were controlled for such as race, education, socioecomonic status, and region. The main outcomes were development of diabetes, hypertension, hyperlipidemia, and heart disease.
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Results:
A total of 76,343 males were diagnosed with male factor infertility, 60,072 males who underwent fertility testing, and 183,742 males that underwent vasectomy (control population). For all men, infertile men had a higher risk of incident hypertension, diabetes, hyperlipidemia, and heart disease when compared to those undergoing vasectomy. Identical associations were found across all education, income, racial, and geographic strata.
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Conclusion:
Our study suggests that men with infertility have a higher risk of cardiometabolic disease in the years following a fertility evaluation regardless of race, region, or socioeconomic status
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