11,612 results match your criteria variation parameter


Coulomb-actuated microbeams revisited: experimental and numerical modal decomposition of the saddle-node bifurcation.

Microsyst Nanoeng 2021 28;7:41. Epub 2021 May 28.

Fraunhofer Institute for Photonic Microsystems IPMS, Dresden, 01109 Germany.

Electrostatic micromechanical actuators have numerous applications in science and technology. In many applications, they are operated in a narrow frequency range close to resonance and at a drive voltage of low variation. Recently, new applications, such as microelectromechanical systems (MEMS) microspeakers (µSpeakers), have emerged that require operation over a wide frequency and dynamic range. Read More

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Bayesian Estimation of the Variation in Strength and Aerobic Physical Performances in Young Eumenorrheic Female College Students during a Menstrual Cycle.

Sports (Basel) 2021 Sep 17;9(9). Epub 2021 Sep 17.

School of Sports Science, The University of Jordan, Amman 11942, Jordan.

Background: The purpose of the present investigation was to examine changes in strength and aerobic physical performances in young eumenorrheic female college students during the menstruation phase and different testing occasions within a menstrual cycle.

Methods: A repeated measure experimental design used to investigate the variation in physical performance from different testing occasions compared to the menstruation phase. Twelve eumenorrhea female college students volunteered to participate in this study. Read More

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September 2021

[Inflammatory Bowel Diseases: Regional Deprivation, Disease Characteristics and Relevant Health Care].

Gesundheitswesen 2021 Sep 24. Epub 2021 Sep 24.

Institut für Sozialmedizin und Epidemiologie, Universität zu Lübeck, Lübeck, Deutschland.

Hintergrund: Regionale Deprivation ist als ökologischer Parameter eine Komponente der sozialen Determinanten von Gesundheit. Zu ihrer Messung stehen in Deutschland der "German Index of Multiple Deprivation" (GIMD) und der "German Index of Socioeconomic Deprivation" (GISD) zur Verfügung. Chronisch entzündliche Darmerkrankungen (CED) sind keine häufigen, aber ernste körperliche Erkrankungen unklarer Ätiologie, mit vergleichsweise frühem Auftreten im Erwachsenenalter, oft chronisch-behandlungsbedürftigem Verlauf und unsicherer Prognose. Read More

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September 2021

The Evolution of Plasmid Transfer Rate in Bacteria and Its Effect on Plasmid Persistence.

Am Nat 2021 Oct 24;198(4):473-488. Epub 2021 Aug 24.

AbstractPlasmids are extrachromosomal segments of DNA that can transfer genes between bacterial cells. Many plasmid genes benefit bacteria but cause harm to human health by granting antibiotic resistance to pathogens. Transfer rate is a key parameter for predicting plasmid dynamics, but observed rates are highly variable, and the effects of selective forces on their evolution are unclear. Read More

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October 2021

Inter-rater and inter-session reliability of lumbar paraspinal muscle composition in a mobile MRI device.

Br J Radiol 2021 Sep 24:20210141. Epub 2021 Sep 24.

University of Potsdam, University Outpatient Clinic, Sports Medicine and Sports Orthopaedics, Potsdam, Germany.

Objective: To assess the reliability of measurements of paraspinal muscle transverse relaxation times (T2 times) between two observers and within one observer on different time points.

Methods: 14 participants (9f/5m, 33 ± 5 years, 176 ± 10 cm, 73 ± 12 kg) underwent 2 consecutive MRI scans (M1,M2) on the same day, followed by 1 MRI scan 13-14 days later (M3) in a mobile 1.5 Tesla MRI. Read More

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September 2021

An Optimal Transport Analysis on Generalization in Deep Learning.

IEEE Trans Neural Netw Learn Syst 2021 Sep 23;PP. Epub 2021 Sep 23.

Deep neural networks (DNNs) have achieved state-of-the-art performance in various learning tasks, such as computer vision, natural language processing, and speech recognition. However, the fundamental theory of generalization still remains obscure in deep learning--why DNN models can generalize well, despite that they are heavily overparametrized in both depth and width? Recently, some work shows that traditional theory of analyzing the generalization error of learning models fails to explain the generalization of DNNs. The failure is mainly because of one simple fact that the worse case analysis of generalization error for learning models would be too loose for models with large parameter space, such as DNNs. Read More

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September 2021

Extrinsic parameter's adjustment and potential implications in Plasmodium falciparum malaria diagnosis.

Microsc Res Tech 2021 Sep 23. Epub 2021 Sep 23.

Department of Statistics and Applied Mathematics, Central University of Tamil Nadu, Thiruvarur, India.

Malaria is a major public health concern, affecting over 3.2 billion people in 91 countries. The advent of digital microscopy and Machine learning with the aim of automating Plasmodium falciparum diagnosis extensively depends on the extracted image features. Read More

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September 2021

English engineer John Smeaton's experimental method(s): Optimisation, hypothesis testing and exploratory experimentation.

Stud Hist Philos Sci 2021 Sep 18;89:283-294. Epub 2021 Sep 18.

Centre for Logic and Philosophy of Science, Vrije Universiteit Brussel, Pleinlaan 2, Room 5B425, B-1050, Brussels, Belgium. Electronic address:

In this paper I provide a detailed account of eighteenth-century engineer John Smeaton's experimental methods, with the aim of bringing our understanding of his work into line with recent research in the history and philosophy of science. Starting from his use of the technique of parameter variation, I identify three distinct methodological aims in the research he carried out on waterwheels, windmills and hydraulic mortars. These aims are: optimisation, hypothesis testing and maxim generation. Read More

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September 2021

Retrospective analysis of interventions to epidemics using dynamic simulation of population behavior.

Math Biosci 2021 Sep 18:108712. Epub 2021 Sep 18.

Division of Applied Mechanics, U.S. FDA/CDRH Silver Spring, MD 20993, USA. Electronic address:

Retrospective analyses of interventions to epidemics, in which the effectiveness of strategies implemented are compared to hypothetical alternatives, are valuable for performing the cost-benefit calculations necessary to optimize infection countermeasures. SIR (susceptible-infected-removed) models are useful in this regard but are limited by the challenge of deciding how and when to update the numerous parameters as the epidemic changes in response to population behaviors. Behaviors of particular interest include facemasks adoption (at various levels) and social distancing. Read More

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September 2021

Disease progression and mortality with untreated HIV infection: evidence synthesis of HIV seroconverter cohorts, antiretroviral treatment clinical cohorts and population-based survey data.

J Int AIDS Soc 2021 Sep;24 Suppl 5:e25784

MRC Centre for Global Infectious Disease Analysis, School of Public Health, Imperial College London, London, UK.

Introduction: Model-based estimates of key HIV indicators depend on past epidemic trends that are derived based on assumptions about HIV disease progression and mortality in the absence of antiretroviral treatment (ART). Population-based HIV Impact Assessment (PHIA) household surveys conducted between 2015 and 2018 found substantial numbers of respondents living with untreated HIV infection. CD4 cell counts measured in these individuals provide novel information to estimate HIV disease progression and mortality rates off ART. Read More

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September 2021

Capturing the dynamics of small populations: A retrospective assessment using long-term data for an island reintroduction.

J Anim Ecol 2021 Sep 21. Epub 2021 Sep 21.

Institute of Zoology, Zoological Society of London, London, UK.

The art of population modelling is to incorporate factors essential for capturing a population's dynamics while otherwise keeping the model as simple as possible. However, it is unclear how optimal model complexity should be assessed, and whether this optimal complexity has been affected by recent advances in modelling methodology. This issue is particularly relevant to small populations because they are subject to complex dynamics but inferences about those dynamics are often constrained by small sample sizes. Read More

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September 2021

Spin-Orbit Charge-Transfer Intersystem Crossing of Compact Naphthalenediimide-Carbazole Electron-Donor-Acceptor Triads.

J Phys Chem B 2021 Sep 20. Epub 2021 Sep 20.

KAUST Solar Center, Division of Physical Sciences and Engineering, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Kingdom of Saudi Arabia.

Compact electron donor-acceptor triads based on carbazole (Cz) and naphthalenediimide (NDI) were prepared to study the spin-orbit charge-transfer intersystem crossing (SOCT-ISC). By variation of the molecular conformation and electron-donating ability of the carbazole moieties, the electronic coupling between the two units was tuned, and as a result charge-transfer (CT) absorption bands with different magnitudes were observed (ε = 4000-18 000 M cm). Interestingly, the triads with NDI attached at the 3-C position or with a phenyl spacer at the position of the Cz moiety, thermally activated delayed fluorescence (TADF) was observed. Read More

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September 2021

Glass transition of ion-containing polymer melts in bulk and thin films.

Soft Matter 2021 Sep 20. Epub 2021 Sep 20.

Department of Materials Science and Engineering, Northwestern University, Evanston, IL 60208, USA.

Ion-containing polymers often are good glass formers, and the glass transition temperature is an important parameter to consider for practical applications, which prescribes the working temperature range for different mechanical and dynamic properties. In this work, we present a systematic molecular dynamics simulation study on the coupling of ionic correlations with the glass transition, based on a generic coarse-grained model of ionic polymers. The variation of the glass transition temperature is examined concerning the influence of the electrostatic interaction strength, charge fraction, and charge sequence. Read More

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September 2021

Changes in Size and Interpretation of Parameter Estimates in Within-Person Models in the Presence of Time-Invariant and Time-Varying Covariates.

Front Psychol 2021 1;12:666928. Epub 2021 Sep 1.

Institut für Psychologie, Münster University, Münster, Germany.

For several decades, cross-lagged panel models (CLPM) have been the dominant statistical model in relationship research for investigating reciprocal associations between two (or more) constructs over time. However, recent methodological research has questioned the frequent usage of the CLPM because, amongst other things, the model commingles within-person associations with between-person associations, while most developmental research questions pertain to within-person processes. Furthermore, the model presumes that there are no third variables that confound the relationships between the longitudinally assessed variables. Read More

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September 2021

Microcomputed tomographic analysis of bone microarchitecture after sinus augmentation with hyaluronic matrix: a case-control study.

Oral Maxillofac Surg 2021 Sep 18. Epub 2021 Sep 18.

Department of Periodontology, Faculty of Dentistry, Hacettepe University, Sıhhiye, 06100, Ankara, Turkey.

Background: The aim of this study was to analyze trabecular microarchitecture of augmented sinuses with hyaluronic matrix and xenograft by microcomputed tomography, and to investigate whether hyaluronic matrix has an effect on the newly formed bone quality.

Materials And Methods: Thirteen patients undergoing maxillary sinus augmentation were included in this split-mouth study. Right and left sinus sites were randomly assigned to test and control group. Read More

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September 2021

Changes of [F]FDG-PET/CT quantitative parameters in tumor lesions by the Bayesian penalized-likelihood PET reconstruction algorithm and its influencing factors.

BMC Med Imaging 2021 Sep 16;21(1):133. Epub 2021 Sep 16.

Department of Nuclear Medicine, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, 3 East Qingchun Rd, Jianggan District, Hangzhou, 310000, Zhejiang, People's Republic of China.

Background: To compare the changes in quantitative parameters and the size and degree of F-fluorodeoxyglucose ([F]FDG) uptake of malignant tumor lesions between Bayesian penalized-likelihood (BPL) and non-BPL reconstruction algorithms.

Methods: Positron emission tomography/computed tomography images of 86 malignant tumor lesions were reconstructed using the algorithms of ordered subset expectation maximization (OSEM), OSEM + time of flight (TOF), OSEM + TOF + point spread function (PSF), and BPL. [F]FDG parameters of maximum standardized uptake value (SUVmax), SUVmean, metabolic tumor volume (MTV), total lesion glycolysis (TLG), and signal-to-background ratio (SBR) of these lesions were measured. Read More

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September 2021

HeaLED: Assessment of skin healing under light-emitting diode (LED) exposure-A randomized controlled study versus placebo.

Lasers Surg Med 2021 Sep 16. Epub 2021 Sep 16.

Dermatology Department, Archet Hospital-CHU, University Côte d'Azur, Nice, France.

Background: Light-emitting diodes (LEDs) in the visible or near-infrared spectrum have been reported to promote wound healing. However, despite being frequently proposed in daily clinical practice, the efficacy of photobiomodulation treatment after a laser procedure relies on very limited clinical data.

Objective: To compare the relative efficacy of LED versus placebo treatment in decreasing erythema and transepidermal water loss (TEWL) after a fractional CO session. Read More

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September 2021

System drift and speciation.

Evolution 2021 Sep 16. Epub 2021 Sep 16.

Molecular and Computational Biology, University of Southern California, Los Angeles, California, 90089, US.

Even if a species' phenotype does not change over evolutionary time, the underlying mechanism may change, as distinct molecular pathways can realize identical phenotypes. Here we use linear system theory to explore the consequences of this idea, describing how a gene network underlying a conserved phenotype evolves, as the genetic drift of small changes to these molecular pathways causes a population to explore the set of mechanisms with identical phenotypes. To do this, we model an organism's internal state as a linear system of differential equations for which the environment provides input and the phenotype is the output, in which context there exists an exact characterization of the set of all mechanisms that give the same input-output relationship. Read More

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September 2021

Linking Macroinvertebrates and Physicochemical Parameters for Water Quality Assessment in the Lower Basin of the Volta River in Ghana.

Environ Manage 2021 Sep 16. Epub 2021 Sep 16.

Aquatic Ecology and Water Quality Management Group, Wageningen University, P.O. Box 47, 6700 AA, Wageningen, The Netherlands.

The health of the lower basin of the Volta River in Ghana was evaluated in January-February and May-June 2016 using physicochemical parameters and benthic macroinvertebrates sampled at 10 locations. Selected environmental variables were compared to accepted environmental water quality standard values where applicable. Principal component analysis (PCA) and redundancy analysis (RDA) were used to analyse the association between the benthic macroinvertebrates distribution and physicochemical variables. Read More

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September 2021

Output factor measurements with multiple detectors in CyberKnife Robotic Radiosurgery System.

J Cancer Res Ther 2021 Jul-Sep;17(4):870-874

Brunei National Cancer Centre, Jerudong, Brunei.

Aim: The aim of this study was to measure and compare the output factor (OF) of a CyberKnife Robotic Radiosurgery System with eight different small field detectors and validate with Technical Report Series (TRS) report 483.

Background: Accurate dosimetry of CyberKnife system is limited due to the challenges in small field dosimetry. OF is a vital dosimetric parameter used in the photon beam modeling and any error would affect the dose calculation accuracy. Read More

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September 2021

Period-doubling route to mixed-mode chaos.

Phys Rev E 2021 Aug;104(2-1):024211

Department of Chemistry, Brandeis University, Waltham, Massachusetts 02453, USA.

Mixed-mode oscillations (MMOs) are a complex dynamical behavior in which each cycle of oscillation consists of one or more large amplitude spikes followed by one or more small amplitude peaks. MMOs typically undergo period-adding bifurcations under parameter variation. We demonstrate here, in a set of three identical, linearly coupled van der Pol oscillators, a scenario in which MMOs exhibit a period-doubling sequence to chaos that preserves the MMO structure, as well as period-adding bifurcations. Read More

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Refractive changes of a new asymmetric intracorneal ring segment with variable thickness and base width: A 2D finite-element model.

PLoS One 2021 15;16(9):e0257222. Epub 2021 Sep 15.

Department of Information Technology and Electrical Engineering, OPTIC Team, Computer-assisted Applications in Medicine Group, ETH Zurich, Zurich, Switzerland.

Purpose: To evaluate the local geometric effects of a unilateral intrastromal ring segment with a combined variation of ring thickness and base width in a finite element simulation, and to compare it against the isolated effect of thickness or base width variation alone.

Methods: A two-dimensional finite-element model of a transversely isotropic cornea was created assuming either axisymmetric stress or plane strain condition. The model geometry was composed of a three-layered corneal tissue (epithelium, anterior and posterior stroma) fixed at the limbus. Read More

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September 2021

Impact of Lipid Peroxidation on the Response of Cell Membranes to High-Speed Equibiaxial Stretching: A Computational Study.

J Phys Chem B 2021 Sep 15. Epub 2021 Sep 15.

Institute of Chemical Materials, China Academy of Engineering and Physics, Mianyang 621900, China.

The difference between diseased and healthy cellular membranes in response to mechanical stresses is crucial for biology, as well as in the development of medical devices. However, the biomolecular mechanisms by which mechanical stresses interact with diseased cellular components remain largely unknown. In this work, we focus on the response of diseased cellular membranes with lipid peroxidation to high-speed tensile loadings. Read More

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September 2021

Clinical importance of preoperative red-cell volume distribution width as a prognostic marker in patients undergoing radical surgery for pancreatic cancer.

Surg Today 2021 Sep 15. Epub 2021 Sep 15.

Department of Pancreatic-Biliary Surgery, Affiliated Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, 1095 Jiefang Ave, Wuhan, 430030, China.

Background And Purpose: A new noninvasive biomarker is being sought to predict the prognosis of patients with pancreatic cancer. Red-cell volume distribution width (RDW), a descriptive parameter for erythrocyte variation, has been shown to have prognostic value for some tumor types. Our purpose was to assess the RDW value to predict the prognosis of patients with pancreatic cancer. Read More

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September 2021

Parameter Estimation of an Epidemic Model with State Constraints.

Appl Math Optim 2021 Sep 8:1-21. Epub 2021 Sep 8.

"Gheorghe Mihoc-Caius Iacob" Institute of Mathematical Statistics and Applied Mathematics of the Romanian Academy, Calea 13 Septembrie 13, Bucharest, Romania.

We consider a mathematical model with five compartments relevant to depict the feature of a certain type of epidemic transmission. We aim to identify some system parameters by means of a minimization problem for a functional involving available measurements for observable compartments, which we treat by an optimal control technique with a state constraint imposed by realistic considerations. The proof of the maximum principle is done by passing to the limit in the conditions of optimality for an appropriate approximating problem. Read More

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September 2021

Accurate Dosimetry for Radiobiology.

Int J Radiat Oncol Biol Phys 2021 Sep 9. Epub 2021 Sep 9.

Medical Radiation Research Center, Department of Medical Physics, School of Medicine and Public Health, University of Wisconsin, Madison, WI 53705. Electronic address:

Purpose: Accurate radiation dose is required to ensure reproducibility in establishing the radiobiological effect in biological systems among institutions. The dose should be the most precise and accurate parameter of the entire process. The goal is a system to provide uniform radiation dose verification among institutions that is traceable to NIST through an ADCL. Read More

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September 2021

Optimization of scanning time of F-FDG whole body PET/CT imaging in obese patients using quadratic dose protocol.

Med J Malaysia 2021 09;76(5):637-642

Institut Kanser Negara, Nuclear Medicine Department, Ministry of Health Malaysia, Malaysia.

Introduction: F-FDG imaging of overweight and obese patients is often challenging due to higher scattering and attenuation. Degradation of positron emission tomography (PET) image quality as the body weight increases is best overcome by using the quadratic dose protocol. Previously the implementation of this protocol on a Bismuth Germanium Oxide (BGO) scintillation crystal-based PET/CT system at Institut Kanser Negara (IKN), Malaysia practices using the linear dose protocol (T=2. Read More

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September 2021

Biological variation data for kidney function related parameter: serum beta trace protein, creatinine and cystatin C from 22 apparently healthy Turkish subjects.

Clin Chem Lab Med 2021 Sep 10. Epub 2021 Sep 10.

Department of Medical Biochemistry, University of Demokrasi, Izmir, Turkey.

Objectives: Biological variation is defined as the variation in analytical concentration between and within individuals, and being aware of this biological variation is important for understanding disease dynamics. The aim of our study is to calculate the within-subject (CV) and between-subject (CV) biological variations of serum creatinine, cystatin C and Beta trace protein (BTP), as well as the reference change value (RCV) and individuality indexes (II), which are used to calculate the glomerular filtration rate while evaluating kidney damage.

Methods: Blood samples were collected from 22 healthy volunteers for 10 consecutive weeks and stored at -80 °C until the day of analysis. Read More

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September 2021

Coupling coordination relationship between ecosystem services and water-land resources for the Daguhe River Basin, China.

PLoS One 2021 10;16(9):e0257123. Epub 2021 Sep 10.

School of Environmental and Municipal Engineering, Qingdao University of Technology, Qingdao, China.

Water and land resource utilization is an important driving force of changes in ecosystem services; therefore, research on multi-parameter coupling systems that consider "ecosystem services, water resources, and land resources" together has key significance for river basins. This study aims to reveal the interaction and mutual influence of ecosystem services and water and land resources in the Daguhe River Basin, China, based on the coupling coordination degree model. The results showed that during the period from 2000 to 2010, the coupling coordination degree values for the years 2000, 2005, and 2010 were 0. Read More

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September 2021

Is developmental rate polymorphism constant? Influence of temperature on the occurrence and constancy of slow and fast development in Zygogramma bicolorata Pallister (Coleoptera: Chrysomelidae).

J Therm Biol 2021 Aug 29;100:103043. Epub 2021 Jun 29.

Ladybird Research Laboratory, Department of Zoology, University of Lucknow, Lucknow, 226007, India. Electronic address:

Temperature plays an important role in different biological activities of organisms. The relationship between temperature and insect development has long been recognized as an important environmental parameter in modeling insect population dynamics. Although few studies have investigated the existence of developmental rate polymorphism within a cohort, the role of abiotic and biotic factors on such developmental variation has so far been meagerly investigated. Read More

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