scholarly journals Multi-ciliated microswimmers–metachronal coordination and helical swimming

2021 ◽  
Vol 44 (6) ◽  
Author(s):  
Sebastian Rode ◽  
Jens Elgeti ◽  
Gerhard Gompper
Keyword(s):  
Hydrodynamic Radius ◽  
Rotational Diffusion ◽  
Spherical Body ◽  
The Body ◽  
Wave Number ◽  
Swimming Velocity ◽  
Main Body ◽  
Phase Lag ◽  
Beat Pattern ◽  
Order Of Magnitude

Abstract The dynamics and motion of multi-ciliated microswimmers with a spherical body and a small number N (with $$5< N < 60$$ 5 < N < 60 ) of cilia with length comparable to the body radius, is investigated by mesoscale hydrodynamics simulations. A metachronal wave is imposed for the cilia beat, for which the wave vector has both a longitudinal and a latitudinal component. The dynamics and motion is characterized by the swimming velocity, its variation over the beat cycle, the spinning velocity around the main body axis, as well as the parameters of the helical trajectory. Our simulation results show that the microswimmer motion strongly depends on the latitudinal wave number and the longitudinal phase lag. The microswimmers are found to swim smoothly and usually spin around their own axis. Chirality of the metachronal beat pattern generically generates helical trajectories. In most cases, the helices are thin and stretched, i.e., the helix radius is about an order of magnitude smaller than the pitch. The rotational diffusion of the microswimmer is significantly smaller than the passive rotational diffusion of the body alone, which indicates that the extended cilia contribute strongly to the hydrodynamic radius. The swimming velocity is found to increase with the cilia number N with a slightly sublinear power law, consistent with the behavior expected from the dependence of the transport velocity of planar cilia arrays on the cilia separation. Graphic abstract

ANALGESIC AND ANTI-INFLAMMATORY EFFECTS OF ACETYLSALICYLIC ACID: PHYSIOLOGICAL MECHANISMS

2020 ◽  
Vol 6(72) (1) ◽  
pp. 197-219
Author(s):  
I. V. Cheretaev ◽  
D. R. Khusainov ◽  
E. N. Chuyan ◽  
M. Yu. Ravaeva ◽  
A. N. Gusev ◽  
...  
Keyword(s):  
Acetylsalicylic Acid ◽  
Physiological Mechanism ◽  
The Body ◽  
Physiological Mechanisms ◽  
Scientific Publications ◽  
Thermal Pain ◽  
Order Of Magnitude ◽  
Anti Inflammatory ◽  
Number Of Publications ◽  
Electrical Stimuli

The purpose of the review is to summarize current literature data and the results of our own research on the analgesic and anti-inflammatory effects of acetylsalicylic acid, as well as the physiological mechanisms underlying them. This acid is the most studied reference representative of salicylates, which is convenient to consider the physiological effects characteristic in general for this group of chemical and medicinal products. Acetylsalicylic acid has analgesic properties against thermal pain and pain caused by electrical stimuli, as well as a pronounced anti-inflammatory effect. The realization of these properties depends on the peculiarities of aspirin metabolism in the body, ion and synaptic mechanisms for controlling the functional state of the cell, neurotransmitter systems of the сentral nervous system, and mechanisms of peripheral and сentral analgesia. Analgesic properties of acetylsalicylic acid founded not only in normal, but also in ultra-small doses. Various physical and especially chemical factors significantly change their effects. This increases the interest in studying the analgesic activity of salicylates and their physiological mechanisms, since such studies can serve as a basis for creating new non-steroidal anti-inflammatory drugs with low toxicity and high safety for patients, and improve the strategy of their practical use. Currently, the most detailed study of the physiological mechanism of analgesic and anti-inflammatory action of aspirin and its main metabolite – salicylic acid. However, it should be note that despite the abundance of existing data obtained in scientific studies of the effects of aspirin and its practical use, there are a number of unexplained aspects of the action of this drug, the mechanism of which has not yet been deciphered. The continuing interest in the effects and mechanisms of action of this drug and in connection with the expansion of its use evidenced by a consistently high number of scientific publications on aspirin in the most famous foreign and domestic publications. At the same time, the number of publications about aspirin is an order of magnitude higher than about any other drug known to humanity.

scholarly journals Internet of things issues related to psychiatry

2021 ◽  
Vol 9 (1) ◽  
Author(s):  
Scott Monteith ◽  
Tasha Glenn ◽  
John Geddes ◽  
Emanuel Severus ◽  
Peter C. Whybrow ◽  
...  
Keyword(s):  
Internet Of Things ◽  
Cognitive Abilities ◽  
Healthcare Providers ◽  
Emotional Reactions ◽  
The Body ◽  
Psychiatric Research ◽  
Main Body ◽  
Personal Safety ◽  
Healthcare Organizations ◽  
Iot Devices

Abstract Background Internet of Things (IoT) devices for remote monitoring, diagnosis, and treatment are widely viewed as an important future direction for medicine, including for bipolar disorder and other mental illness. The number of smart, connected devices is expanding rapidly. IoT devices are being introduced in all aspects of everyday life, including devices in the home and wearables on the body. IoT devices are increasingly used in psychiatric research, and in the future may help to detect emotional reactions, mood states, stress, and cognitive abilities. This narrative review discusses some of the important fundamental issues related to the rapid growth of IoT devices. Main body Articles were searched between December 2019 and February 2020. Topics discussed include background on the growth of IoT, the security, safety and privacy issues related to IoT devices, and the new roles in the IoT economy for manufacturers, patients, and healthcare organizations. Conclusions The use of IoT devices will increase throughout psychiatry. The scale, complexity and passive nature of data collection with IoT devices presents unique challenges related to security, privacy and personal safety. While the IoT offers many potential benefits, there are risks associated with IoT devices, and from the connectivity between patients, healthcare providers, and device makers. Security, privacy and personal safety issues related to IoT devices are changing the roles of manufacturers, patients, physicians and healthcare IT organizations. Effective and safe use of IoT devices in psychiatry requires an understanding of these changes.

scholarly journals SARS-CoV-2: is there neuroinvasion?

2021 ◽  
Vol 18 (1) ◽  
Author(s):  
Conor McQuaid ◽  
Molly Brady ◽  
Rashid Deane
Keyword(s):  
Respiratory Distress ◽  
Vascular Dysfunction ◽  
Multiorgan Failure ◽  
Neurological Complications ◽  
Wide Distribution ◽  
The Body ◽  
Health Conditions ◽  
Main Body ◽  
Beneficial Effects ◽  
The Brain

Abstract Background SARS-CoV-2, a coronavirus (CoV), is known to cause acute respiratory distress syndrome, and a number of non-respiratory complications, particularly in older male patients with prior health conditions, such as obesity, diabetes and hypertension. These prior health conditions are associated with vascular dysfunction, and the CoV disease 2019 (COVID-19) complications include multiorgan failure and neurological problems. While the main route of entry into the body is inhalation, this virus has been found in many tissues, including the choroid plexus and meningeal vessels, and in neurons and CSF. Main body We reviewed SARS-CoV-2/COVID-19, ACE2 distribution and beneficial effects, the CNS vascular barriers, possible mechanisms by which the virus enters the brain, outlined prior health conditions (obesity, hypertension and diabetes), neurological COVID-19 manifestation and the aging cerebrovascualture. The overall aim is to provide the general reader with a breadth of information on this type of virus and the wide distribution of its main receptor so as to better understand the significance of neurological complications, uniqueness of the brain, and the pre-existing medical conditions that affect brain. The main issue is that there is no sound evidence for large flux of SARS-CoV-2 into brain, at present, compared to its invasion of the inhalation pathways. Conclusions While SARS-CoV-2 is detected in brains from severely infected patients, it is unclear on how it gets there. There is no sound evidence of SARS-CoV-2 flux into brain to significantly contribute to the overall outcomes once the respiratory system is invaded by the virus. The consensus, based on the normal route of infection and presence of SARS-CoV-2 in severely infected patients, is that the olfactory mucosa is a possible route into brain. Studies are needed to demonstrate flux of SARS-CoV-2 into brain, and its replication in the parenchyma to demonstrate neuroinvasion. It is possible that the neurological manifestations of COVID-19 are a consequence of mainly cardio-respiratory distress and multiorgan failure. Understanding potential SARS-CoV-2 neuroinvasion pathways could help to better define the non-respiratory neurological manifestation of COVID-19.

scholarly journals Ovarian tissue freezing and activation after thawing: an update

2021 ◽  
Vol 26 (1) ◽  
Author(s):  
Li-fan Peng
Keyword(s):  
Granulosa Cells ◽  
Clinical Decision Making ◽  
Ovarian Function ◽  
Ovarian Tissue ◽  
Clinical Decision ◽  
The Body ◽  
Endocrine Function ◽  
Ovarian Tissue Cryopreservation ◽  
Main Body ◽  
Tissue Cryopreservation

Abstract Background With the growth of women’s age, ovarian failure can be caused by various factors. For the women who need chemotherapy because of cancer factors, the preservation of fertility is more urgent. The treatment of cancer is also a process in which all tissues and organs of the body are severely damaged, especially in the reproductive system. Main body As a new fertility preservation technology, autologous ovarian tissue cryopreservation and transplantation is developing rapidly and showing great potentiality in preserving ovarian endocrine function of young cervical cancer patients. Vitrification and slow freezing are two common techniques applied for ovarian tissue cryopreservation. Thus, cryopreserved/thawed ovarian tissue and transplantation act as an important method to preserve ovarian function during radiotherapy and chemotherapy, and ovarian cryopreservation by vitrification is a very effective and extensively used method to cryopreserve ovaries. The morphology of oocytes and granulosa cells and the structure of organelles were observed under the microscope of histology; the hormone content in the stratified culture medium of granulosa cells with the diameter of follicle was used to evaluate the development potential of ovarian tissue, and finally the ovarian tissue stimulation was determined by the technique of ovarian tissue transplantation. Conclusions Although there are some limitations, the team members still carry out this review to provide some references and suggestions for clinical decision-making and further clinical research.

Maximizing the efficiency of a flexible propulsor using experimental optimization

2015 ◽  
Vol 767 ◽  
pp. 430-448 ◽  
Author(s):  
Daniel B. Quinn ◽  
George V. Lauder ◽  
Alexander J. Smits
Keyword(s):  
Leading Edge ◽  
The Body ◽  
Phase Lag ◽  
Force Measurements ◽  
Experimental Optimization ◽  
Image Velocimetry ◽  
Flexible Panel ◽  
Gradient Based ◽  
Power Scale ◽  
Effective Angle

AbstractExperimental gradient-based optimization is used to maximize the propulsive efficiency of a heaving and pitching flexible panel. Optimum and near-optimum conditions are studied via direct force measurements and particle image velocimetry (PIV). The net thrust and power scale predictably with the frequency and amplitude of the leading edge, but the efficiency shows a complex multimodal response. Optimum pitch and heave motions are found to produce nearly twice the efficiencies of optimum heave-only motions. Efficiency is globally optimized when (i) the Strouhal number is within an optimal range that varies weakly with amplitude and boundary conditions; (ii) the panel is actuated at a resonant frequency of the fluid–panel system; (iii) heave amplitude is tuned such that trailing-edge amplitude is maximized while the flow along the body remains attached; and (iv) the maximum pitch angle and phase lag are chosen so that the effective angle of attack is minimized. The multi-dimensionality and multi-modality of the efficiency response demonstrate that experimental optimization is well-suited for the design of flexible underwater propulsors.

‘Inactive’ motion and pressure fluctuations in turbulent boundary layers

1967 ◽  
Vol 30 (2) ◽  
pp. 241-258 ◽  
Author(s):  
P. Bradshaw
Keyword(s):  
Boundary Layer ◽  
Outer Layer ◽  
Pressure Fluctuations ◽  
Turbulent Energy ◽  
Viscous Sublayer ◽  
Wave Number ◽  
Noticeable Effect ◽  
Frequency Spectra ◽  
Active Motion ◽  
Order Of Magnitude

Townsend's (1961) hypothesis that the turbulent motion in the inner region of a boundary layer consists of (i) an ‘active’ part which produces the shear stress τ and whose statistical properties are universal functions of τ and y, and (ii) an ‘inactive’ and effectively irrotational part determined by the turbulence in the outer layer, is supported in the present paper by measurements of frequency spectra in a strongly retarded boundary layer, in which the ‘inactive’ motion is particularly intense. The only noticeable effect of the inactive motion is an increased dissipation of kinetic energy into heat in the viscous sublayer, supplied by turbulent energy diffusion from the outer layer towards the surface. The required diffusion is of the right order of magnitude to explain the non-universal values of the triple products measured near the surface, which can therefore be reconciled with universality of the ‘active’ motion.Dimensional analysis shows that the contribution of the ‘active’ inner layer motion to the one-dimensional wave-number spectrum of the surface pressure fluctuations varies as τ2w/k1 up to a wave-number inversely proportional to the thickness of the viscous sublayer. This result is strongly supported by the recent measurements of Hodgson (1967), made with a much smaller ratio of microphone diameter to boundary-layer thickness than has been achieved previously. The disagreement of the result with most other measurements is attributed to inadequate transducer resolution in the other experiments.

Theory of Short Wave Excitation

1986 ◽  
Vol 30 (03) ◽  
pp. 147-152
Author(s):  
Yong Kwun Chung
Keyword(s):  
Incident Wave ◽  
Characteristic Length ◽  
Finite Depth ◽  
Short Wave ◽  
The Body ◽  
Wave Number ◽  
Floating Body ◽  
Wave Excitation ◽  
Exciting Forces ◽  
Wave Exciting Forces

When the wavelength of the incident wave is short, the total surface potential on a floating body is found to be 2∅ i & O (m-l∅ i) on the lit surface and O (m-l∅ j) on the shadow surface where ~b i is the potential of the incident wave and m the wave number in water of finite depth. The present approximation for wave exciting forces and moments is reasonably good up to X/L ∅ 1 where h is the wavelength and L the characteristic length of the body.

Contact force analysis on two-fingered robot grasping

2020 ◽  
pp. 146441932096402
Author(s):  
Jiun-Ru Chen ◽  
Wei-En Chen ◽  
CH Liu ◽  
Yin-Tien Wang ◽  
CB Lin ◽  
...  
Keyword(s):  
Kinetic Analysis ◽  
Contact Force ◽  
Numerical Procedure ◽  
Spherical Body ◽  
Solution Procedure ◽  
The Body ◽  
Contact Forces ◽  
Grasping Forces ◽  
Robot Grasping ◽  
Force Displacement

A procedure for inverse kinetic analysis on two hard fingers grasping a hard sphere is proposed in this study. Contact forces may be found for given linear and angular accelerations of a spherical body. Elastic force-displacement relations predicted by Hertz contact theory are used to remove the indeterminancy produced by rigid body modelling. Two types of inverse kinetic analysis may be dealt with. Firstly, as the fingers impose a given tightening displacement on the body, and carry it to move with known accelerations, corresponding grasping forces may be determined by a numerical procedure. In this procedure one contact force may be chosen as the principal unknown, and all other contact forces are expressed in terms of this force. The numerical procedure is hence very efficient since it deals with a problem with only one unknown. The solution procedure eliminates slipping thus only nonslip solutions, if they exist, are found. Secondly, when the body is moving with known accelerations, if the grasping direction of the two fingers is also known, then the minimum tightening displacement required for non-sliding grasping may be obtained in closed form. In short, the proposed technique deals with a grasping system that has accelerations, and in this study the authors show that indeterminancy may be used to reduce the complexity of the problem.

DIRECT GENETIC AND POSTNATAL MATERNAL GENETIC EFFECTS ON BODY COMPOSITION IN MICE SELECTED FOR BODY WEIGHT

1979 ◽  
Vol 21 (1) ◽  
pp. 43-56 ◽  
Author(s):  
J. F. Hayes ◽  
E. J. Eisen
Keyword(s):  
Body Weight ◽  
Genetic Effects ◽  
The Body ◽  
Control Line ◽  
Ether Extract ◽  
Correlated Responses ◽  
Relative Growth Rates ◽  
Order Of Magnitude ◽  
Body Components ◽  
Water Percent

Line crossfostering techniques were used to study differences among selected and control lines of mice in direct genetic and postnatal maternal genetic influences on preweaning (day 12) body weight and composition. The lines were selected for high (H6) and low (L6) 6-week body weight and the control line (C2) was maintained by random selection. There were positive correlated responses to selection in both direct genetic and postnatal maternal genetic effects on body weight and weights of all body components (P < 0.01) except for water and ash weight in H6. The correlated responses in postnatal maternal genetic effects were of the same order of magnitude as those in direct genetic effects. Correlated responses were greater in L6 than in H6. Correlated responses in direct genetic effects were positive (P < 0.01) for water percent in H6 and ether extract percent in L6, and negative (P < 0.01) for water percent and lean percent in L6. Correlated responses in postnatal maternal genetic effects were positive for ether extract percent and negative for water percent (P < 0.01). Correlated responses were far greater in L6 than in H6 and were greater for postnatal maternal genetic effects than for direct genetic effects. Analyses of covariance results indicated line differences in the relative growth rates of the body components.

Locomotion in Burrowing and Vagrant Wolf Spiders (Lycosidae)

1981 ◽  
Vol 92 (1) ◽  
pp. 305-321 ◽  
Author(s):  
T. M. WARD ◽  
W. F. HUMPHREYS
Keyword(s):  
Wolf Spider ◽  
The Body ◽  
Power Stroke ◽  
Phase Lag ◽  
Running Speed ◽  
Wolf Spiders ◽  
High Speeds ◽  
Phase Lags ◽  
The Relationship

Locomotion in the vagrant wolf spider Trochosa ruricola is compared to that in the burrow dwelling wolf spider Lycosa tarentula (Araneae: Lycosidae). L. tarentula takes relatively shorter steps than T. ruricola. At high speeds T. ruricola approximates an alternating tetrapod gait but this does not occur in L. tarentula. Phase lag differs between species and varies marginally with speed except for ipsilateral phase lags in L. tarentula which are erratic if they include leg 1. In both species the protraction/retraction ratio is directly related to both running speed and stepping frequency, but the relationship is more marked in L. tarentula. The protraction/retraction ratio is more variable in leg 1 and varies between legs along the body but by a greater amount in L. tarentula. In these spiders, in contrast to the situation in many insects, both the duration of protraction and retraction show marked inverse relationships to stepping frequency. The power stroke (retraction) occupies a variable proportion of the stepping cycle, which is not the case in other spiders, and this proportion is lower than for other spiders. It is suggested that the first pair of legs is used more for sensory than for locomotory purpose and that this is more marked in the burrow dwelling species, L. tarentula.

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