scholarly journals Study on Flow Behavior of Parallel Lumped-Model under Constant Flow for Bronchial Tree

2021 ◽  
Vol 40 (2) ◽  
pp. 86-94
Author(s):  
MU Ahmmed ◽  
M Sultanab
Keyword(s):  
Steady State ◽  
Flow Behavior ◽  
Inertial Force ◽  
Bronchial Tree ◽  
Constant Flow ◽  
Experimental Conditions ◽  
Lumped Model ◽  
Constant Flow Rate ◽  
Inertial Flow ◽  
In Series

Redistribution of flow in the bronchial tree is an important factor that enhances gas exchange in the lungs, especially, in diseased lungs. The bifurcated bronchial tree is like an electric network in series and parallel. A lumped-model of parallel system for constant flow rate is solved analytically to demonstrate the intrinsic characteristics and the dynamic behavior of the system. Inertial and capacitive time constants are calculated for 19th generation airways of human lung to control the solution. The investigation revealed that (i) higher inertial force takes more time to maximize the inertial flow to steady state  and more time to minimize the resistive flow to steady state  and (ii) the compliant effect is negligible for a relatively higher inertial time constant,  on the same experimental conditions. GANIT J. Bangladesh Math. Soc. 40.2 (2020) 86–94

An anti-settling sample delivery instrument for serial femtosecond crystallography

2012 ◽  
Vol 45 (4) ◽  
pp. 674-678 ◽  
Author(s):  
Lukas Lomb ◽  
Jan Steinbrener ◽  
Sadia Bari ◽  
Daniel Beisel ◽  
Daniel Berndt ◽  
...  
Keyword(s):  
Constant Flow ◽  
Syringe Pump ◽  
Experimental Conditions ◽  
Flow Rates ◽  
X Ray ◽  
Constant Flow Rate ◽  
Significant Impairment ◽  
Working Principle ◽  
After Hours ◽  
Serial Femtosecond Crystallography

Serial femtosecond crystallography (SFX) using X-ray free-electron laser (FEL) sources has the potential to determine the structures of macromolecules beyond the limitation of radiation damage and without the need for crystals of sufficient size for conventional crystallography. In SFX, a liquid microjet is used to inject randomly oriented crystals suspended in their storage solution into the FEL beam. Settling of crystals in the reservoir prior to the injection has been found to complicate the data collection. This article details the development of an anti-settling sample delivery instrument based on a rotating syringe pump, capable of producing flow rates and liquid pressures necessary for the operation of the injector. The device has been used successfully with crystals of different proteins, with crystal sizes smaller than 20 µm. Even after hours of continuous operation, no significant impairment of the experiments due to sample settling was observed. This article describes the working principle of the instrument and sets it in context with regard to the experimental conditions used for SFX. Hit rates for longer measuring periods are compared with and without the instrument operating. Two versions of the instrument have been developed, which both deliver sample at a constant flow rate but which differ in their minimum liquid flow rates and maximum pressures.

Recirculatory Spinal Subarachnoid Perfusions in Dogs

Neurosurgery ◽  
1977 ◽  
Vol 1 (1) ◽  
pp. 48-56 ◽  
Author(s):  
Frederick H. Sklar ◽  
Donlin M. Long
Keyword(s):  
Cerebrospinal Fluid ◽  
Steady State ◽  
Albumin Concentration ◽  
Syringe Pump ◽  
Experimental Conditions ◽  
Ventriculocisternal Perfusion ◽  
Resting Pressure ◽  
In Series ◽  
Intracranial Pressures ◽  
Concentration Changes

Abstract Open-ended ventriculocisternal perfusion techniques for determining cerebrospinal fluid production and absorption rates are severely restricted by the absolute requirement that steady state conditions be present. A new closed recirculatory spinal perfusion technique is described. Because steady state equilibrium is not necessary, numerous determinations at multiple intracranial pressures or under varied experimental conditions are possible within relatively brief perfusion periods. Cerebrospinal fluid (CSF) and nondiffusible albumin tracer are rapidly recirculated through the spinal subarachnoid space in a cephalad direction. The concentration of fluorescein-tagged albumin is continuously monitored as the CSF is circulated through a fluorometric flow cell. Measured continuously, intracranial pressure (ICP) is regulated by changing the volume of the external perfusion circuit with a syringe pump connected in series to the recirculatory spinal perfusion. CSF formation and absorption rates are calculated from measurements of albumin concentration, concentration changes with time, ICP, syringe pump infusion rate, and the external perfusion circuit volume. In dogs, data can be collected after only 45 minutes for mixing; perfusions at four or five intracranial pressures in addition to normal resting pressure can be completed within 2 to 3 hours. The data from 15 perfusions in 14 dogs are presented. The method provides normal resting pressure values of CSF production and absorption consistent with those values in the literature determined by traditional ventriculocisternal perfusion techniques. Determinations at multiple intracranial pressures suggest a proportional relationship between absorption and ICP. No consistent acute change in CSF formation with pressures to 50 mm Hg can be inferred from these data.

scholarly journals Improving the Hydraulic Effects Resulting from the Use of a Submerged Biofiter to Enhance Water Quality in Polluted Streams

2021 ◽  
Vol 18 (23) ◽  
pp. 12351
Author(s):  
Atef A. El-Saiad ◽  
Hany F. Abd-Elhamid ◽  
Zeinab I. Salama ◽  
Martina Zeleňáková ◽  
Erik Weiss ◽  
...  
Keyword(s):  
Water Quality ◽  
Flow Rate ◽  
Water Depth ◽  
Empirical Equation ◽  
Flow Behavior ◽  
The Self ◽  
Constant Flow ◽  
Purification Process ◽  
Constant Flow Rate ◽  
Case Comparison

Water scarcity is one of the most serious problems facing many countries. In addition, water pollution could lose more water. A submerged biofilter (SB) is used to enhance the self-purification process in polluted streams. However, most previous studies have focused on the efficiency of SB to remove pollutants and there is a lack of studies investigating the hydraulic changes in streams. The current paper aimed to study the hydraulic effects of SB on the flow behavior in streams and how to improve it. An empirical equation for determining the flow rate through SB was developed. Different cases were studied to improve the hydraulic effects resulting from the use of SB. The effect of increasing SB length was tested using different SB lengths. The results showed that increasing the length increased the upstream water depth (h1) and relative heading up (h1/h2). In the second case, comparison between continuous and fragmented SB was tested. The results showed that a fragmented biofilter increased the upstream water depth and the relative heading up. Case three tested the effect of SB height. Different SB heights were tested with a fixed length and constant flow rate. The results revealed that the upstream water depth and relative heading up decreased when the biofilter height decreased. Case four tested the effect of SB with a fixed volume and constant flow rate. In this case, the length and height of SB were changed where the volume was fixed. The results showed that the relative heading up decreased when the SB height decreased and the length increased, which revealed that the SB height can improve the hydraulic impacts. Finally, the use of SB to improve the water quality in polluted streams led to an increase of the relative heading up, which can be reduced by decreasing the height of SB.

Validation of a monetary Taylor Aggression Paradigm: Associations with trait aggression and role of provocation sequence

2020 ◽  
Author(s):  
J Konzok ◽  
L Kreuzpointner ◽  
GI Henze ◽  
L Wagels ◽  
C Kärgel ◽  
...  
Keyword(s):  
Random Sequence ◽  
Reactive Aggression ◽  
Reaction Time Task ◽  
Competitive Reaction ◽  
Experimental Conditions ◽  
Fixed Sequence ◽  
Taylor Aggression Paradigm ◽  
Trait Aggression ◽  
Significant Difference ◽  
In Series

© 2020 Elsevier Inc. The Taylor Aggression Paradigm (TAP) is widely used to measure reactive aggression in laboratory settings. While modified versions (mTAPs) with various stimulus characteristics (shocks, noise, pressure, heat) have already been established, a modified version with monetary stimuli has only been introduced very recently. In this experiment, 209 young healthy participants (104 males, 105 females) completed a mock Competitive Reaction Time Task (CRTT) with a fictional opponent with preprogrammed 40 win and 60 lose trials. In lose trials, participants were provoked by subtracting a low (0–20 euro cents), medium (30–60 cents) or high (70–90 cents) amount of money from their fictitious account. Provocation stimuli were either presented randomly or in a fixed sequence (experimental conditions). In contrast to a random sequence, the fixed sequence was generated by repeating trials from the same provocation category in series of three. Linear mixed models (LMMs) considering aggression trajectories revealed significant effects of provocation (low, medium, high) and trait aggression (K-FAF) on reactive aggression. Men showed significantly higher reactive aggression levels than women. In regard to provocation sequence, we found no significant difference in reactive aggression between the random vs. fixed stimulus sequences. The findings provide new evidence supporting the view that the monetary mTAP is able to induce as well as capture reactive aggression in the laboratory. Additionally, we found no advantage of a fixed sequence as the level of reactive aggression in a given trial appeared to be mainly predicted by the preceding provocation trial.

scholarly journals The steady-state visual evoked potential (SSVEP) reflects the activation of cortical object representations: evidence from semantic stimulus repetition

2020 ◽  
Author(s):  
Elise L. Radtke ◽  
Ulla Martens ◽  
Thomas Gruber
Keyword(s):  
Steady State ◽  
Object Representation ◽  
Sensory Information ◽  
Familiar Object ◽  
Object Representations ◽  
Stimulus Repetition ◽  
Experimental Conditions ◽  
Repetition Suppression ◽  
Task Irrelevant ◽  
Visual Evoked

AbstractWe applied high-density EEG to examine steady-state visual evoked potentials (SSVEPs) during a perceptual/semantic stimulus repetition design. SSVEPs are evoked oscillatory cortical responses at the same frequency as visual stimuli flickered at this frequency. In repetition designs, stimuli are presented twice with the repetition being task irrelevant. The cortical processing of the second stimulus is commonly characterized by decreased neuronal activity (repetition suppression). The behavioral consequences of stimulus repetition were examined in a companion reaction time pre-study using the same experimental design as the EEG study. During the first presentation of a stimulus, we confronted participants with drawings of familiar object images or object words, respectively. The second stimulus was either a repetition of the same object image (perceptual repetition; PR) or an image depicting the word presented during the first presentation (semantic repetition; SR)—all flickered at 15 Hz to elicit SSVEPs. The behavioral study revealed priming effects in both experimental conditions (PR and SR). In the EEG, PR was associated with repetition suppression of SSVEP amplitudes at left occipital and repetition enhancement at left temporal electrodes. In contrast, SR was associated with SSVEP suppression at left occipital and central electrodes originating in bilateral postcentral and occipital gyri, right middle frontal and right temporal gyrus. The conclusion of the presented study is twofold. First, SSVEP amplitudes do not only index perceptual aspects of incoming sensory information but also semantic aspects of cortical object representation. Second, our electrophysiological findings can be interpreted as neuronal underpinnings of perceptual and semantic priming.

Steady-State Flow Behavior of CO2 Foam

2004 ◽  
Author(s):  
J.S. Kim ◽  
Y. Dong ◽  
W.R. Rossen
Keyword(s):  
Steady State ◽  
Flow Behavior ◽  
Steady State Flow ◽  
State Flow ◽  
Co2 Foam

scholarly journals Participation of plasma membrane proteins in the formation of tight junction by cultured epithelial cells

1983 ◽  
Vol 96 (3) ◽  
pp. 693-702 ◽  
Author(s):  
EB Griepp ◽  
WJ Dolan ◽  
ES Robbins ◽  
DD Sabatini
Keyword(s):  
Protein Synthesis ◽  
Steady State ◽  
Tight Junction ◽  
Messenger Rna ◽  
Freeze Fracture ◽  
Epithelial Cell Line ◽  
Experimental Conditions ◽  
Tight Junction Formation ◽  
Junction Formation ◽  
Spinner Culture

Measurements of the transepithelial electrical resistance correlated with freeze-fracture observations have been used to study the process of tight junction formation under various experimental conditions in monolayers of the canine kidney epithelial cell line MDCK. Cells derived from previously confluent cultures and plated immediately after trypsin- EDTA dissociation develop a resistance that reaches its maximum value of several hundred ohms-cm(2) after approximately 24 h and falls to a steady-state value of 80-150 ohms- cm(2) by 48 h. The rise in resistance and the development of tight junctions can be completely and reversibly prevented by the addition of 10 μg/ml cycloheximide at the time of plating, but not when this inhibitor is added more than 10 h after planting. Thus tight junction formation consists of separable synthetic and assembly phases. These two phases can also be dissociated and the requirement for protein synthesis after plating eliminated if, following trypsinization, the cells are maintained in spinner culture for 24 h before plating. The requirement for protein synthesis is restored, however, if cells maintained in spinner culture are treated with trypsin before plating. Actinomycin D prevents development of resistance only in monolayers formed from cells derived from sparse rather than confluent cultures, but new mRNA synthesis is not required if cells obtained from sparse cultures are maintained for 24 h in spinner culture before plating. Once a steady-state resistance has been reached, its maintenance does not require either mRNA or protein synthesis; in fact, inhibition of protein synthesis causes a rise in the resistance over a 30-h period. Following treatments that disrupt the junctions in steady- state monolayers recovery of resistance also does not require protein synthesis. These observations suggest that proteins are involved in tight junction formation. Such proteins, which do not turn over rapidly under steady-state conditions, are destroyed by trypsinization and can be resynthesized in the absence of stable cell-cell or cell-substratum contact. Messenger RNA coding for proteins involved in tight junction formation is stable except when cells are sparsely plated, and can also be synthesized without intercellular contacts or cell-substratum attachment.

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