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arXiv 2023年

作者： Barrett, Aaron Fogelson, Aaron L. Gregory Forest, M. Gruninger, Cole Lim, Sookkyung Griffith, Boyce E. Department of Mathematics University of Utah Salt Lake CityUT United States Departments of Mathematics and Biomedical Engineering University of Utah Salt Lake CityUT United States Department of Mathematics University of North Carolina Chapel HillNC United States Department of Applied Physical Sciences University of North Carolina Chapel HillNC United States Department of Biomedical Engineering University of North Carolina Chapel HillNC United States Carolina Center for Interdisciplinary Applied Mathematics University of North Carolina Chapel HillNC United States Department of Mathematical Sciences University of Cincinnati CincinnatiOH United States Computational Medicine Program University of North Carolina School of Medicine Chapel HillNC United States McAllister Heart Institute University of North Carolina School of Medicine Chapel HillNC United States

Microorganism motility often takes place within complex, viscoelastic fluid environments, e.g., sperm in cervicovaginal mucus and bacteria in biofilms. In such complex fluids, strains and stresses generated by the microorganism are stored and relax across a spectrum of length and time scales and the complex fluid can be driven out of its linear response regime. Phenomena not possible in viscous media thereby arise from feedback between the swimmer and the complex fluid, making swimming efficiency co-dependent on the propulsion mechanism and fluid properties. Here we parameterize a flagellar motor and filament properties together with elastic relaxation and nonlinear shear-thinning properties of the fluid in a computational immersed boundary model. We then explore swimming efficiency, defined as a particular flow rate divided by the torque required to spin the motor, over this parameter space. Our findings indicate that motor efficiency (measured by the volumetric flow rate) can be boosted or degraded by relatively moderate or strong shear-thinning of the viscoelastic environment. Copyright © 2023, The Authors. All rights reserved.

关键词： Shear thinning

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Generalized nonbacktracking bounds on the influence in independent cascade models

The Journal of Machine Learning Research

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The Journal of Machine Learning Research 2020年第1期21卷 1112-1147页

作者： Emmanuel Abbe Sanjeev Kulkarni Eun Jee Lee Program in Applied and Computational Mathematics and Department of Electrical Engineering Princeton University Princeton NJ Department of Electrical Engineering Princeton University Princeton NJ Program in Applied and Computational Mathematics Princeton University Princeton NJ

This paper develops deterministic upper and lower bounds on the influence measure in a network, more precisely, the expected number of nodes that a seed set can influence in the independent cascade model. In particular, our bounds exploit r-nonbacktracking walks and Fortuin--Kasteleyn--Ginibre (FKG) type inequalities, and are computed by message passing algorithms. Further, we provide parameterized versions of the bounds that control the trade-off between efficiency and accuracy. Finally, the tightness of the bounds is illustrated on various network models.

关键词： influence estimation nonbacktracking walk message passing social networks independent cascade model

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Heart Disease Diagnosis by Machine Learning Techniques

Heart Disease Diagnosis by Machine Learning Techniques

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Science, engineering and Business for Sustainable Development Goals (SEB-SDG), International Conference on

作者： Tashi Lhamo Geeta Arora Homan Emadifar Ezekiel Olaoluwa Omole Laith Abualigah Peter Onu Grace Idowu Olaleru Ade-Omowaye Joshua Department of Mathematics School of Chemical Engineering and Physical Sciences Lovely Professional University India Department of Mathematics Saveetha Institute of Medical and Technical Sciences Saveetha University Tamil Nadu India MEU Research Unit Middle East University. Amman Jordan Department of Physical Science Mathematics Programme Landmark University Omu-Aran Nigeria Good Health and Well-Being Research Group Landmark University SDG3 Omu-Aran Nigeria Artificial Intelligence and Sensing Technologies (AIST) Research Center University of Tabuk Tabuk Saudi Arabia Hourani Center for Applied Scientific Research Al-Alhiyya Amman University Amman Jordan Department of Mechanical Engineering (Mechatronics) Landmark University. Omu-Aran Nigeria Department of Electrical and Information Engineering Landmark University Omu-Aran Nigeria

ISBN: (数字)9798350358155

ISBN: (纸本)9798350358162

Disease diagnosis is a crucial component of healthcare for early disease detection and treatment. Recent machine learning techniques have improved efficiency and accuracy due to the abundance of available medical data. In this study, various algorithms for diagnosing heart disease are examined, including Random Forest (RF), Decision Tree (DT), K-Nearest Neighbor (KNN), Logistic Regression (LR), Naive Bayes (NB), Ensemble Learning and Support Vector Machine (SVM). This study’s findings will advance disease diagnosis methods and build a more efficient healthcare system. Medical professionals can use machine learning to diagnose diseases, provide better patient care, and save lives.

关键词： Heart Support vector machines Machine learning algorithms Accuracy Nearest neighbor methods Bayes methods Medical diagnosis

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Identification of β-Caryophyllene (BCP) in Aceh patchouli essential oil (PEO) using gas chromatography-mass pectrophotometry (GC-MS) 2

Identification of β-Caryophyllene (BCP) in Aceh patchouli e...

引用

2nd International Conference on Agriculture and Bioindustry, ICAGRI 2020

作者： Sufriadi, E. Meilina, H. Munawar, A.A. Muhammad, S. Idroes, R. Graduate School of Mathematics and Applied Sciences Universitas Syiah Kuala Banda Aceh23111 Indonesia Department of Chemistry Faculty of Mathematics and Natural Sciences Universitas Syiah Kuala Banda Aceh23111 Indonesia Chemical Engineering Department Faculty of Engineering Universitas Syiah Kuala Banda Aceh23111 Indonesia Pui Nilam Aceh Universitas Syiah Kuala Banda Aceh23111 Indonesia Agricultural Technology Department Universitas Syiah Kuala Banda Aceh23111 Indonesia Department of Pharmacy Faculty of Mathematics and Natural Sciences Universitas Syiah Kuala Banda Aceh23111 Indonesia

This study aimed to determine the composition of β-Caryophyllene (BCP) content in patchouli oil from various regions in Aceh. The data from GC-MS analysis can also describe the type of BCP isomer most commonly found in Aceh patchouli. This research used Aceh Pogostemon cablin Benth patchouli oil from 17 different locations. Samples were analyzed using TSQ™ 9000 Triple Quadrupole GC-MS/MS (Thermo Scientific) with TraceGOLD TG-1MS GC Columns. The mean BCP retention time was 14.64 minutes, with a standard deviation (SD) of 0.16. Only one type of BCP compound isomer appeared, namely Bicyclo [7.2.0] undec-4-ene, 4,11,11-trimethyl-8-methylene-, [1R-(1R∗, 4Z, 9S∗)]. The results also showed that the average BCP level was 5.51%. Aceh patchouli contains a much higher BCP level than the minimum commercial target (3.4-3.5%). The MS spectrum data also showed a high similarity between the patchouli oil sample fragmentation and the compound library. © Published under licence by IOP Publishing Ltd.

关键词： Gas chromatography

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Indentation of Geometrically Exact Adhesive Beams

SSRN

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SSRN 2023年

作者： Suryanarayanan, Krishnan Bhuvana, T. Sharma, Ishan Das, Sovan Lal Mechanics and Applied Mathematics Group Indian Institute of Technology Kanpur Uttar Pradesh Kanpur208016 India Department of Mechanical Engineering Indian Institute of Technology Kanpur Uttar Pradesh Kanpur208016 India Department of Space Science and Astronomy Indian Institute of Technology Kanpur Uttar Pradesh Kanpur208016 India Phyical and Chemical Biology Laboratory Department of Mechanical Engineering IIT Palakkad Kerala Palakkad678623 India

We investigate the indentation of thin adhesive beams by a rigid frictionless circular punch in two-dimensions through computations and experiments. A non-linear geometrically exact (GE) beam formulation that allows for arbitrarily large displacements and rotations is employed for the thin beam. The Karush-Kuhn-Tucker condition for unilateral contact is adapted to model adhesive interaction in a nonlinear finite element (FE) framework. In this contact is enforced through a penalty method and adhesion is incorporated through two different cohesive zone models (CZMs), viz. exponential and bilinear. The indentation of the adhesive GE beam is then studied in terms of the variations of the applied force, the pressure distribution, the crosssectional rotation and the sizes of the contact area and the adhesive zone for different indentation extents, adhesive strengths, punch radii, beam thicknesses and end supports. We find that the system is largely agnostic to the CZM utilized, as well as the type of end supports unless the contact area spans the beam. At the same time, thinner beams tend to initiate contact with a punch more easily, and are harder to detach. We then demonstrate that thin beams may undergo large rotations even if the indentation is small, which necessitates a nonlinear beam theory. Under such conditions approximating a circular punch by a parabolic one introduces errors. Finally, we conduct experiments on clamped adhesive beams made of two different types of PDMS (polydimethyl-siloxane) and various thicknesses, and find a good match with our computations. © 2023, The Authors. All rights reserved.

关键词： Adhesion

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A multiple-timing analysis of temporal ratcheting

arXiv

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arXiv 2022年

作者： Hashemi, Aref Gilman, Edward T. Khair, Aditya S. Department of Applied and Computational Mathematics and Statistics University of Notre Dame Notre DameIN United States Courant Institute New York University New YorkNY United States Department of Mathematics Rice University HoustonTX United States Department of Chemical Engineering Carnegie Mellon University PittsburghPA United States

We develop a two-timing perturbation analysis to provide quantitative insights on the existence of temporal ratchets in an exemplary system of a particle moving in a tank of fluid in response to an external vibration of the tank. We consider two-mode vibrations with angular frequencies ω and αω, where α is a rational number. If α is a ratio of odd and even integers (e.g., 12234 ), the system yields 3 a net response: here, a nonzero time-average particle velocity. Our first-order perturbation solution predicts the existence of temporal ratchets for α = 2. Furthermore, we demonstrate, for a reduced model, that the temporal ratcheting effect for α = 32 and 34 appears at the third-order perturbation solution. More importantly, we find closed form formulas for the magnitude and direction of the induced net velocities for these α values. On a broader scale, our methodology offers a new mathematical approach to study the complicated nature of temporal ratchets in physical systems. Copyright © 2022, The Authors. All rights reserved.

关键词： Timing circuits

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Modeling coexisting GSF and shear instabilities in rotating stars

arXiv

引用

arXiv 2021年

作者： Chang, Eonho Garaud, Pascale Department of Applied Mathematics Baskin School of Engineering University of California Santa CruzCA95064 United States Graduate Interdisciplinary Program in Applied Mathematics University of Arizona TucsonAZ85721 United States

Zahn's widely-used model for turbulent mixing induced by rotational shear has recently been validated (with some caveats) in non-rotating shear flows. It is not clear, however, whether his model remains valid in the presence of rotation, even though this was its original purpose. Furthermore, new instabilities arise in rotating fluids, such as the Goldreich-Schubert-Fricke (GSF) instability. Which instability dominates when more than one can be excited, and how they influence each other, were open questions that this paper answers. To do so, we use direct numerical simulations of diffusive stratified shear flows in a rotating triply-periodic Cartesian domain located at the equator of a star. We find that either the GSF instability or the shear instability tends to take over the other in controlling the system, suggesting that stellar evolution models only need to have a mixing prescription for each individual instability, together with a criterion to determine which one dominates. However, we also find that it is not always easy to predict which instability "wins" for given input parameters, because the diffusive shear instability is subcritical, and only takes place if there is a finite-amplitude turbulence "primer" to seed it. Interestingly, we find that the GSF instability can in some cases play the role of this primer, thereby providing a pathway to excite the subcritical shear instability. This can also drive relaxation oscillations, that may be observable. We conclude by proposing a new model for mixing in the equatorial regions of stellar radiative zones due to differential rotation. Copyright © 2021, The Authors. All rights reserved.

关键词： Stability

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Fabrication of a Polariton Cavity via Mid-IR Laser Excitation

Fabrication of a Polariton Cavity via Mid-IR Laser Excitatio...

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Conference on Lasers and Electro-Optics (CLEO)

作者： Cecilia Y. Chen Samuel L. Moore Rishi Maiti Anjaly Rajendran Kenji Watanabe Takashi Taniguchi Song Liu James H. Edgar James Hone Dmitri N. Basov Alexander L. Gaeta Department of Electrical Engineering Columbia University New York New York USA Department of Physics Columbia University New York New York USA Department of Applied Physics and Applied Mathematics Columbia University New York New York USA Department of Mechanical Engineering Columbia University New York New York USA Research Center for Functional Materials National Institute for Materials Science Tsukuba Japan International Center for Materials Nanoarchitectonics National Institute for Materials Science Tsukuba Japan Tim Taylor Department of Chemical Engineering Kansas State University Manhattan Kansas USA

We fabricate polariton cavities in hBN with Q-factors > 70. Our approach is based on strong, resonant phonon excitation at 7.3 µm with femtosecond pulses causing the sample to "unzip" and produce a p... 详细信息

ISBN: (纸本)9781957171258

关键词： Electron beam lithography Femtosecond pulses Laser sources Near field scanning optical microscopy Quantum cascade semiconductor lasers Reflection

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Using Machine Learning to Study the Effects of Genetic Predisposition on Brain Aging in the UK Biobank

Using Machine Learning to Study the Effects of Genetic Predi...

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IEEE International Symposium on Biomedical Imaging

作者： Karen Ardila Emily Munro Fernando Vega Aashka Mohite Charlotte Curtis Amanda V. Tyndall M. Ethan MacDonald Department of Electronic and Automation Biomedical Engineering Universidad Autónoma de Manizales Manizales Colombia Department of Biomedical Engineering University of Calgary Calgary Canada Department of Electrical & Software Engineering University of Calgary Calgary Canada Department of Radiology University of Calgary Calgary Canada Hotchkiss Brain Institute University of Calgary Calgary Canada Mitacs Globalink Research Internship Program Canada Department of Chemical Engineering University of Calgary Calgary Canada Department of Mathematics and Computing Mount Royal University Calgary Canada Department of Medical Genetics University of Calgary Calgary Canada

The influence of genetic predisposition on changes in brain morphology during aging remains largely unknown. This study explores the effects of genetic predisposition on three key brain regions: total brain volume (TBV), lateral ventricular volume (LVV), and total hippocampal volume (THV). The brain age gap estimate (BrainAGE) biomarker is used as an input to a genome-wide association study to determine which single nucleotide polymorphisms (SNPs) and genes are associated with accelerated brain aging. Six independent significant SNPs were found to contribute to accelerated morphological changes: TBV had associations on chromosome 17 linked with brain aging, and the total THV had independent significant associations in the APOC1 and TOMM40 gene regions related to neurodegeneration. Lastly, LVV presented a possible novel discovery in the gene NUAK1, known to play a role in cellular senescence. This study provides a framework to uncover complex associations between brain aging physiology and genetics.

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Confined active matter in external fields

arXiv

引用

arXiv 2022年

作者： Shaik, Vaseem A. Peng, Zhiwei Brady, John F. Elfring, Gwynn J. Department of Mechanical Engineering Institute of Applied Mathematics University of British Columbia VancouverBCV6T 1Z4 Canada Division of Chemistry and Chemical Engineering California Institute of Technology PasadenaCA91125 United States

We analyze a dilute suspension of active particles confined between walls and subjected to fields that can modulate particle speed as well as orientation. Generally, the particle distribution is different in the bulk compared to near the walls. In the bulk, particles tend to accumulate in the regions of low speed, but in the presence of an orienting field, particles rotate to align with the field and accumulate downstream in the field direction. At the walls, particles tend to accumulate pointing into the walls and thereby exert pressure on walls. But the presence of strong orienting fields can cause the particles to reorient away from the walls, and hence shows a possible mechanism for preventing contamination of surfaces. The pressure at the walls depends on the wall separation and the field strengths. This work demonstrates how multiple fields with different functionalities can be used to control active matter under confinement. Copyright © 2022, The Authors. All rights reserved.

关键词： Suspensions (fluids)

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