scholarly journals Interplay of motility and polymer-driven depletion forces in the initial stages of bacterial aggregation

Soft Matter ◽  
2019 ◽  
Vol 15 (35) ◽  
pp. 7071-7079 ◽  
Author(s):  
Michael K. Porter ◽  
Asher Preska Steinberg ◽  
Rustem F. Ismagilov
Keyword(s):  
Time Scales ◽  
Bacterial Motility ◽  
Bacterial Aggregation ◽  
Viscous Solutions ◽  
Short Time ◽  
Depletion Forces

Counterintuitively, bacterial motility aids polymer-driven depletion aggregation at short time scales by enabling collisions in viscous solutions.

The Spread of Pollutants from Harbour Sludge Depots

1984 ◽  
Vol 16 (3-4) ◽  
pp. 623-633
Author(s):  
M Loxham ◽  
F Weststrate
Keyword(s):  
Time Scales ◽  
Molecular Diffusion ◽  
Near Field ◽  
Parameter Analysis ◽  
Migration Patterns ◽  
Long Time ◽  
Dilution Effects ◽  
Short Time ◽  
Harbour Sludge

It is generally agreed that both the landfill option, or the civil techniques option for the final disposal of contaminated harbour sludge involves the isolation of the sludge from the environment. For short time scales, engineered barriers such as a bentonite screen, plastic sheets, pumping strategies etc. can be used. However for long time scales the effectiveness of such measures cannot be counted upon. It is thus necessary to be able to predict the long term environmenttal spread of contaminants from a mature landfill. A model is presented that considers diffusion and adsorption in the landfill site and convection and adsorption in the underlaying aquifer. From a parameter analysis starting form practical values it is shown that the adsorption behaviour and the molecular diffusion coefficient of the sludge, are the key parameters involved in the near field. The dilution effects of the far field migration patterns are also illustrated.

scholarly journals Impact of tumor-parenchyma biomechanics on liver metastatic progression: a multi-model approach

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Yafei Wang ◽  
Erik Brodin ◽  
Kenichiro Nishii ◽  
Hermann B. Frieboes ◽  
Shannon M. Mumenthaler ◽  
...  
Keyword(s):  
Time Scales ◽  
Constitutive Relations ◽  
Elastic Tissue ◽  
Metastatic Progression ◽  
Patient Death ◽  
Metastatic Growth ◽  
Tumor Parenchyma ◽  
Short Time ◽  
Model Approach

AbstractColorectal cancer and other cancers often metastasize to the liver in later stages of the disease, contributing significantly to patient death. While the biomechanical properties of the liver parenchyma (normal liver tissue) are known to affect tumor cell behavior in primary and metastatic tumors, the role of these properties in driving or inhibiting metastatic inception remains poorly understood, as are the longer-term multicellular dynamics. This study adopts a multi-model approach to study the dynamics of tumor-parenchyma biomechanical interactions during metastatic seeding and growth. We employ a detailed poroviscoelastic model of a liver lobule to study how micrometastases disrupt flow and pressure on short time scales. Results from short-time simulations in detailed single hepatic lobules motivate constitutive relations and biological hypotheses for a minimal agent-based model of metastatic growth in centimeter-scale tissue over months-long time scales. After a parameter space investigation, we find that the balance of basic tumor-parenchyma biomechanical interactions on shorter time scales (adhesion, repulsion, and elastic tissue deformation over minutes) and longer time scales (plastic tissue relaxation over hours) can explain a broad range of behaviors of micrometastases, without the need for complex molecular-scale signaling. These interactions may arrest the growth of micrometastases in a dormant state and prevent newly arriving cancer cells from establishing successful metastatic foci. Moreover, the simulations indicate ways in which dormant tumors could “reawaken” after changes in parenchymal tissue mechanical properties, as may arise during aging or following acute liver illness or injury. We conclude that the proposed modeling approach yields insight into the role of tumor-parenchyma biomechanics in promoting liver metastatic growth, and advances the longer term goal of identifying conditions to clinically arrest and reverse the course of late-stage cancer.

Variations in the depositional fluxes of cosmogenic beryllium on short time scales

2011 ◽  
Vol 45 (17) ◽  
pp. 2836-2841 ◽  
Author(s):  
M. Mann ◽  
J. Beer ◽  
F. Steinhilber ◽  
J.A. Abreu ◽  
M. Christl ◽  
...  
Keyword(s):  
Time Scales ◽  
Short Time

scholarly journals Nonlinearities of heart rate variability in animal models of impaired cardiac control: contribution of different time scales

2017 ◽  
Vol 123 (2) ◽  
pp. 344-351 ◽  
Author(s):  
Luiz Eduardo Virgilio Silva ◽  
Renata Maria Lataro ◽  
Jaci Airton Castania ◽  
Carlos Alberto Aguiar Silva ◽  
Helio Cesar Salgado ◽  
...  
Keyword(s):  
Nonlinear Dynamics ◽  
Heart Rate ◽  
Heart Rate Variability ◽  
Time Scales ◽  
Multiscale Entropy ◽  
Time Frequency ◽  
Cardiac Control ◽  
Long Time ◽  
Nonlinear Features ◽  
Short Time

Heart rate variability (HRV) has been extensively explored by traditional linear approaches (e.g., spectral analysis); however, several studies have pointed to the presence of nonlinear features in HRV, suggesting that linear tools might fail to account for the complexity of the HRV dynamics. Even though the prevalent notion is that HRV is nonlinear, the actual presence of nonlinear features is rarely verified. In this study, the presence of nonlinear dynamics was checked as a function of time scales in three experimental models of rats with different impairment of the cardiac control: namely, rats with heart failure (HF), spontaneously hypertensive rats (SHRs), and sinoaortic denervated (SAD) rats. Multiscale entropy (MSE) and refined MSE (RMSE) were chosen as the discriminating statistic for the surrogate test utilized to detect nonlinearity. Nonlinear dynamics is less present in HF animals at both short and long time scales compared with controls. A similar finding was found in SHR only at short time scales. SAD increased the presence of nonlinear dynamics exclusively at short time scales. Those findings suggest that a working baroreflex contributes to linearize HRV and to reduce the likelihood to observe nonlinear components of the cardiac control at short time scales. In addition, an increased sympathetic modulation seems to be a source of nonlinear dynamics at long time scales. Testing nonlinear dynamics as a function of the time scales can provide a characterization of the cardiac control complementary to more traditional markers in time, frequency, and information domains. NEW & NOTEWORTHY Although heart rate variability (HRV) dynamics is widely assumed to be nonlinear, nonlinearity tests are rarely used to check this hypothesis. By adopting multiscale entropy (MSE) and refined MSE (RMSE) as the discriminating statistic for the nonlinearity test, we show that nonlinear dynamics varies with time scale and the type of cardiac dysfunction. Moreover, as complexity metrics and nonlinearities provide complementary information, we strongly recommend using the test for nonlinearity as an additional index to characterize HRV.

A BARGAIN WITH NATURE

PEDIATRICS ◽  
1978 ◽  
Vol 62 (6) ◽  
pp. 1035-1035
Author(s):  
R. J. H.
Keyword(s):  
Nervous System ◽  
Time Scales ◽  
Genetic Information ◽  
Human Species ◽  
Genetic Inheritance ◽  
New Learning ◽  
Short Time

Humans have a longer childhood relative to our lifespan than any other species. This provides immense plasticity-ability to learn from their environment and their culture. Most organisms on Earth depend on their genetic information which is prewired into their nervous system. While our behavior is still significantly controlled by our genetic inheritance, we have, through our brains, a much richer opportunity to blaze new behavioral and cultural pathways on short time scales. We have made a bargain with nature; our children will be difficult to raise, but their capacity for new learning will greatly enhance the chances of survival of the human species.

Attempts to Reconcile the Long and the Short-Time Scales in Cosmogony

Science ◽  
1935 ◽  
Vol 82 (2116) ◽  
pp. 53-53
Author(s):  
Paul S. Epstein
Keyword(s):  
Time Scales ◽  
Short Time

scholarly journals Time Resolved Emission of Sidestream Smoke Particles

1992 ◽  
Vol 15 (2) ◽  
pp. 53-57
Author(s):  
R Dittmann ◽  
HJ Feld ◽  
BH Müller ◽  
W Schneider
Keyword(s):  
Time Scales ◽  
Time Resolved ◽  
Smoke Particles ◽  
Sidestream Smoke ◽  
Different Types ◽  
Short Time ◽  
Aerosol Properties

AbstractBy means of the dispersion quotient method, the aerosol properties of freshly produced sidestream smoke were measured during the puff and subsequent interpuff period. These measurements were made on short time scales and at high aerosol concentrations. Examples are presented, which show the influence of different combustion conditions during the puff (resulting from different degrees of ventilation and different types of tobacco) on the emission of sidestream particles during the interpuff period. The ratio of the volume concentrations of the particles before and during a puff is reduced by ventilation and is nearly unchanged by the variation of the tobacco type.

scholarly journals Learning to play the piano with the Supernumerary Robotic 3rd Thumb

2020 ◽  
Author(s):  
Ali Shafti ◽  
Shlomi Haar ◽  
Renato Mio Zaldivar ◽  
Pierre Guilleminot ◽  
A. Aldo Faisal
Keyword(s):  
Motor Learning ◽  
Time Scales ◽  
Motor Coordination ◽  
Human Subjects ◽  
A Priori ◽  
Musical Score ◽  
Short Time ◽  
Human Augmentation ◽  
Individual Motor ◽  
Individual Human

AbstractWe wanted to study the ability of our brains and bodies to be augmented by supernumerary robot limbs, here extra fingers. We developed a mechanically highly functional supernumerary robotic 3rd thumb actuator, the SR3T, and interfaced it with human users enabling them to play the piano with 11 fingers. We devised a set of measurement protocols and behavioural “biomarkers”, the Human Augmentation Motor Coordination Assessment (HAMCA), which allowed us a priori to predict how well each individual human user could, after training, play the piano with a two-thumbs-hand. To evaluate augmented music playing ability we devised a simple musical score, as well as metrics for assessing the accuracy of playing the score. We evaluated the SR3T (supernumerary robotic 3rd thumb) on 12 human subjects including 6 naïve and 6 experienced piano players. We demonstrated that humans can learn to play the piano with a 6-fingered hand within one hour of training. For each subject we could predict individually, based solely on their HAMCA performance before training, how well they were able to perform with the extra robotic thumb, after training (training end-point performance). Our work demonstrates the feasibility of robotic human augmentation with supernumerary robotic limbs within short time scales. We show how linking the neuroscience of motor learning with dexterous robotics and human-robot interfacing can be used to inform a priori how far individual motor impaired patients or healthy manual workers could benefit from robotic augmentation solutions.

scholarly journals A Tropospheric Emission Spectrometer HDO/H<sub>2</sub>O retrieval simulator for climate models

2012 ◽  
Vol 12 (6) ◽  
pp. 13827-13880
Author(s):  
R. D. Field ◽  
C. Risi ◽  
G. A. Schmidt ◽  
J. Worden ◽  
A. Voulgarakis ◽  
...  
Keyword(s):  
Time Scales ◽  
General Circulation ◽  
Climate Models ◽  
Circulation Model ◽  
Satellite Measurement ◽  
Climate Simulations ◽  
Accurate Comparison ◽  
Free Running ◽  
The Tropics ◽  
Short Time

Abstract. Retrievals of the isotopic composition of water vapor from the Aura Tropospheric Emission Spectrometer (TES) have unique value in constraining moist processes in climate models. Accurate comparison between simulated and retrieved values requires that model profiles that would be poorly retrieved are excluded, and that an instrument operator be applied to the remaining profiles. Typically, this is done by sampling model output at satellite measurement points and using the quality flags and averaging kernels from individual retrievals at specific places and times. This approach is not reliable when the modeled meteorological conditions influencing retrieval sensitivity are different from those observed by the instrument at short time scales, which will be the case for free-running climate simulations. In this study, we describe an alternative, "categorical" approach to applying the instrument operator, implemented within the NASA GISS ModelE general circulation model. Retrieval quality and averaging kernel structure are predicted empirically from model conditions, rather than obtained from collocated satellite observations. This approach can be used for arbitrary model configurations, and requires no agreement between satellite-retrieved and modeled meteorology at short time scales. To test this approach, nudged simulations were conducted using both the retrieval-based and categorical operators. Cloud cover, surface temperature and free-tropospheric moisture content were the most important predictors of retrieval quality and averaging kernel structure. There was good agreement between the δD fields after applying the retrieval-based and more detailed categorical operators, with increases of up to 30‰ over the ocean and decreases of up to 40‰ over land relative to the raw model fields. The categorical operator performed better over the ocean than over land, and requires further refinement for use outside of the tropics. After applying the TES operator, ModelE had δD biases of −8‰ over ocean and −34‰ over land compared to TES δD, which were less than the biases using raw modeled δD fields.

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