scholarly journals The Evolutionary Characteristics of Reservoir Microstructure under Long-Term Waterflooding Development and Its Fractal Description

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Fengjiao Wang ◽  
Xu Wang ◽  
Yikun Liu ◽  
Qingjun Deng ◽  
Jianjun Xu ◽  
...  
Keyword(s):  
Pore Structure ◽  
Physical Simulation ◽  
Structural Parameters ◽  
Fractal Theory ◽  
Evolution Model ◽  
Structure Evolution ◽  
Before And After ◽  
Water Cut ◽  
The Relationship

Generally, long-term waterflooding development often leads to the change of reservoir pore and clay mineral composition, which results in the change of permeability and wettability. In order to explore the relationship between core micropore structure and water cut, based on physical simulation experiments and fractal theory, we proposed a fractal evolutionary model to describe the evolution characteristics of microstructure of long-term water driving reservoirs. In this paper, core pore structure by SEM was first conducted to analyze the change of core pore structure before and after waterflooding under the conditions of magnification of 200 times, 800 times, and 2000 times, respectively. Then, conventional and constant rate mercury injection tests were combined to perform the comparative analysis of core structural parameters before and after waterflooding. Finally, a micropore-throat structure evolution model of core was established. Research shows that the connectivity of larger pores becomes better after long-term water driving, the degree of heterogeneity weakens, and the micro heterogeneity of small pores becomes stronger and stronger. The throat characteristics change in a complex manner, the radius tends to increase, and the sorting becomes better, while the connectivity of small throat changes complex. In general, the heterogeneity of throat increases with the time of water injection in reservoirs with low porosity and permeability. On the basis of fractal theory and variation characteristics of rock pore structure in water driving reservoirs, we have established a micropore-throat structure evolution model of core pore-throat characteristics. This fractal evolution model quantitatively characterized the complexity and evolution law of pore structure and clarified the relationship between fractal dimension of core pore structure and water cut under different stages of water driving.

scholarly journals Long-term complications after stent assist coiling dependent on clopidogrel response

BMC Neurology ◽  
2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Kenji Shoda ◽  
Yukiko Enomoto ◽  
Yusuke Egashira ◽  
Takamasa Kinoshita ◽  
Daisuke Mizutani ◽  
...  
Keyword(s):  
Acute Phase ◽  
Platelet Reactivity ◽  
Unruptured Aneurysms ◽  
Hemorrhagic Events ◽  
Before And After ◽  
Verifynow Assay ◽  
Previously Treated ◽  
The Relationship ◽  
Delayed Phase

Abstract Background Dual antiplatelet therapy (DAPT) is necessary for stent assisted coiling. However, long term use of DAPT has a potential risk of hemorrhagic events. We aimed to examine the relationship between clopidogrel reactivity and complications. Methods Patients who underwent stent assisted coiling for unruptured aneurysms or previously treated aneurysms and received periprocedural DAPT in our institution between August 2011 to March 2020 were included. Platelet reactivity for clopidogrel was measured by VerifyNow assay system, and we defined the cut off value of P2Y12 Reaction Units (PRU) at 208 and classified patients as hypo-responders (PRU≧208) or responders (PRU<208). The rates of hemorrhagic and thrombotic events within 30 days (acute phase) and 30 days after the procedure (delayed phase) were compared between the two groups. Furthermore, changes in hemoglobin levels were measured before and after the procedure and at chronic stages (1 to 6 months thereafter). Results From 61 patients included in this study, 36 patients were hypo-responders and 25 patients were responders. Hemorrhagic events occurred 8.0% only in responders in the acute phase (p = 0.16), and 2.78% in hypo-responders and 20.0% in responders in the delayed phase (p = 0.037). Changes in hemoglobin levels before and after the procedure were 1.22 g/dl in hypo-responders and 1.74 g/dl in responders (p = 0.032) while before the procedure and chronic stages they were 0.39 g/dl in hypo-responders and 1.39 g/dl in responders (p <  0.01). Thrombotic events were not significantly different between the two groups. Conclusion Long term use of DAPT after stent assisted coiling is related to hemorrhagic events in the delayed phase. Preventing for hemorrhagic events, the duration of DAPT should be carefully considered in clopidogrel responders.

scholarly journals Coach Mid-Season Replacement and Team Performance in Professional Soccer

2011 ◽  
Vol 28 (1) ◽  
pp. 115-122 ◽  
Author(s):  
Carlos Lago-Peñas
Keyword(s):  
Team Performance ◽  
Positive Impact ◽  
Short Term ◽  
Shock Effect ◽  
Professional Soccer ◽  
Before And After ◽  
Using Data ◽  
The Relationship ◽  
The Empirical Analysis

Coach Mid-Season Replacement and Team Performance in Professional SoccerThe coaching carousel or turnover is an extreme but frequently occurring phenomenon in soccer. Among the reasons for firing a coach, the most common is the existence of a shock-effect: a new coach would be able to motivate the players better and therefore to improve results. Using data from the Spanish Soccer League during the seasons from 1997-1998 to 2006-2007, this paper investigates the relationship between team performance and coach change over time. The empirical analysis shows that the shock effect of a turnover has a positive impact on team performance in the short term. Results reveal no impact of coach turnover in the long term. The favourable short-term impact on team performance of a coach turnover is followed by continued gradual worsening of results. The turnover effect is non-existent when the comparison between the new coach and the old coach is done over 10, 15 or 20 matches before and after termination.

scholarly journals Capillary Water Absorption and Micro Pore Connectivity of Concrete with Fractal Analysis

Crystals ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 892
Author(s):  
Xiangqun Ding ◽  
Xinyu Liang ◽  
Yichao Zhang ◽  
Yanfeng Fang ◽  
Jinghai Zhou ◽  
...  
Keyword(s):  
Pore Structure ◽  
Water Absorption ◽  
Fractal Theory ◽  
Mineral Admixtures ◽  
Capillary Water ◽  
Capillary Water Absorption ◽  
Connectivity Probability ◽  
Fractal Characteristics ◽  
Different Diameters ◽  
The Relationship

This study focuses on the relationship between the complexity of pore structure and capillary water absorption of concrete, as well as the connection behavior of concrete in specific directions. In this paper, the water absorption of concrete with different binders was tested during the curing process, and the pore structure of concrete was investigated by mercury intrusion porosimetry (MIP). The results show that the water absorption of concrete with mineral admixtures is lower, mainly due to the existence of reasonable pore structure. The effect of slag on concrete modification is more remarkable comparing with fly ash. In addition, the analysis shows that the pore with different diameters has different fractal characteristics. The connectivity probability and water absorption of unidirectional chaotic pore are linearly correlated with the pore diameter of 50–550 nm, and the correlation coefficient reaches a very significant level, and detailed analysis was undertaken to interpret these results based on fractal theory.

Active Participation of Care Partners in a Physical Activity Intervention alongside People with Stroke: A Feasibility Study

2021 ◽  
pp. e20200035
Author(s):  
Reed Handlery ◽  
Elizabeth Regan ◽  
Allison Foster Lewis ◽  
Chelsea Larsen ◽  
Kaci Handlery ◽  
...  
Keyword(s):  
Physical Activity ◽  
Social Support ◽  
Physical Activity Intervention ◽  
Care Partners ◽  
Before And After ◽  
Physical Activity Adherence ◽  
Ongoing Support ◽  
The Relationship

Purpose: This study investigated the feasibility of a physical activity intervention for people with stroke and their care partners and the role social support plays in physical activity adherence. Method: The study used a single-group, pretest–posttest design with follow-up. Participants were adults with chronic stroke and their care partners. The intervention consisted of 8 weeks of structured, group-based physical activity classes, followed by 19 weeks of self-directed physical activity. Recruitment, adherence, safety, and retention were assessed. Familial social support was assessed before and after the 8-week structured portion and again 19 weeks later. Results: A total of 21 participants (15 people with stroke, 6 care partners), mean (SD) age 67.6 (11.6) years, were recruited; 19 (90.5%) completed the 19-week assessment. No adverse events were experienced during the programme. Attendance during the 8-week portion was better than during the 19-week portion (mean difference 0.95; p < 0.001; 95% CI: 0.71, 1.19 visits/wk). No relationship was found between social support and physical activity adherence ( p > 0.05). Conclusions: Involvement of care partners in a physical activity intervention is feasible and safe. Both people with stroke and their care partners may require ongoing support to participate in long-term physical activity. The relationship between social support and physical activity adherence requires further study.

Activity-mediated changes in feed-forward inhibition in the dentate commissural pathway: relationship to EPSP/spike dissociation in the converging perforant path

1993 ◽  
Vol 69 (1) ◽  
pp. 165-173 ◽  
Author(s):  
R. A. Tomasulo ◽  
J. J. Ramirez
Keyword(s):  
Perforant Path ◽  
Excitatory Postsynaptic Potential ◽  
Feed Forward ◽  
Pulse Trains ◽  
Before And After ◽  
Commissural Pathway ◽  
High Stimulus ◽  
The Relationship ◽  
Feed Forward Inhibition

1. We tested the hypothesis that long-term synaptic potentiation (LTP)-associated excitatory postsynaptic potential (EPSP)/spike dissociation in the dentate gyrus (DG) is determined, in part, by changes in the feed-forward inhibition evoked by perforant path (PP) stimulation. The dentate commissural pathway (CP) and the PP activate a common pool of interneurons. Therefore a change in synaptic efficacy in the inhibitory circuit due to activation of one pathway could lead to changes in inhibitory efficacy in the other. The relationship between changes in feed-forward inhibition in the CP and EPSP/spike (E-S) functions in the PP should provide information about the site(s) of synaptic modification. 2. In urethan-anesthetized rats, we measured the inhibition of evoked PP population spikes by the CP at interstimulus intervals of 6 and 12 ms. This measure of commissural inhibition and conventional E-S functions for the PP input to the DG were obtained before and after 1) PP tetany (400 Hz, 8-pulse trains) at low, medium, and high stimulus intensities, and 2) CP tetany (200 Hz, 7-pulse trains). 3. Low-intensity PP conditioning (just above population spike threshold) led to a decrease in CP inhibition and large left shifts of the E-S function. High- and medium-intensity PP conditioning yielded increases in commissural inhibition and smaller leftward E-S shifts. 4. Commissural conditioning led to increases in commissural inhibition and inconsistent changes in the E-S functions.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Establishment and application of a structure evolution model for aqueous foam based on fractal theory

RSC Advances ◽  
2017 ◽  
Vol 7 (7) ◽  
pp. 3650-3659 ◽  
Author(s):  
Fei Wang ◽  
Zhaomin Li ◽  
Hailong Chen ◽  
Xibin Zhang
Keyword(s):  
Fractal Dimension ◽  
Fractal Theory ◽  
Evolution Model ◽  
Structure Evolution ◽  
Exponential Equation ◽  
New Model ◽  
Model Based ◽  
Aqueous Foam ◽  
Non Linear ◽  
Evolution Trend

A new model based on fractal theory is proposed for the simulation of aqueous foam. It reveals that the evolution trend of the fractal dimension of foam is non-linear with the changing of time following an exponential equation.

scholarly journals Study on the Relationship between Pore Structure and Uniaxial Compressive Strength of Cemented Paste Backfill by Using Air-Entraining Agent

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Fengwen Zhao ◽  
Jianhua Hu ◽  
Dongjie Yang ◽  
Ye Kuang ◽  
Hongxing Xiao ◽  
...  
Keyword(s):  
Pore Structure ◽  
Fractal Theory ◽  
Total Pore Volume ◽  
Linear Increase ◽  
Theory Analysis ◽  
Structure Changes ◽  
Small Pore ◽  
Paste Backfill ◽  
Air Entraining Agents ◽  
The Relationship

To control pores in the backfill, the air-entraining agents (AEAs) are used as an admixture to realize the pore structure changes under artificial action and explore the effect of pore structure on strength. Two AEAs at different dosages were added to the backfill. The relationship was then analyzed between them from the macro- and mesoscopic aspects. The results indicate that AEA can regulate pore structure changes of AEACPB. With the increase in AEA content, the total pore volume of different pore sizes in AEACPB increases, in which the proportion of big and medium pore gradually increases while the proportion of small pore gradually decreases. The AEACPB’s UCS is linearly negatively correlated with the porosity and pore percentage, which is the primary factor affecting the AEACPB of the pore structure. When the total pores’ volume in the AEACPB is constant, the influence of different pore structures differs. A higher proportion of small pores leads to a linear increase in strength; a higher proportion of medium pores leads to a linear decrease in strength; and a higher proportion of big pores leads to an exponential decrease in strength. And the fractal dimension has a linear negative correlation with the UCS by fractal theory analysis.

scholarly journals The dependence between the structural-morphological features mixes 0.8SiO2/0.2Al2O3 from the time of mechanicall treatment

2021 ◽  
Vol 22 (3) ◽  
pp. 516-521
Author(s):  
Yu.V. Yavorsky' ◽  
Ya.V. Zaulichny ◽  
M.V. Karpets ◽  
A.I. Dudka ◽  
A.B. Hrubiak ◽  
...  
Keyword(s):  
Mechanical Treatment ◽  
Structural Parameters ◽  
Coherent Scattering ◽  
Lattice Parameter ◽  
Morphological Features ◽  
Sem Images ◽  
X Ray ◽  
Before And After ◽  
Perfect Mixing ◽  
The Relationship

This paper highlights the relationship between changes in structural and morphological features, electronic structure and exanging of time mechanical treatment at microbraker (MBT). Scaning electron microscopy revealed a change in the morphological features of nanoscale powders. From the comparison of SEM images of 0.8SiO2/0.2Al2О3 mixture before and after MBT, it is established that due to MBT, the agglomerates of the initial components are simultaneously crushed with perfect mixing particles of oxides between each other and the formation of new agglomerates with a denser structure. The increase in processing time leads to an increase in the density of the nanocomposite. The effect of time of mechanical treatment  on the structural parameters and phase composition of mixtures of silicon dioxide and titanium were studied using the method of X-ray structural analysis. The established agglomeration is accompanied by a change in the lattice parameter c with a change in the regions of coherent scattering of crystalline Al2О3. Ultra-soft X-ray emission spectroscopy was used to study the distribution of Op-, Sisd- and Alsd- valence electrons in 0.8SiO2/0.2Al2О3 powder mixtures after the different time of mechanicall treatment. An increase in atomic charges has been measured and can be explained by the transfer of electrons from Si and Al to O atoms in split Opπ-binding states.

scholarly journals Predicting the cumulative medical load of COVID-19 outbreaks after the peak in daily fatalities

2020 ◽  
Author(s):  
Claudius Gros ◽  
Roser Valenti ◽  
Lukas Schneider ◽  
Benedikt Gutsche ◽  
Dimitrije Markovic
Keyword(s):  
Sir Model ◽  
Cumulative Number ◽  
Hospitalised Patients ◽  
Before And After ◽  
The Status ◽  
Containment Measures ◽  
Short And Long Term ◽  
The Relationship ◽  
Fixed Period

The distinct ways the COVID-19 pandemics has been unfolding in different countries and regions suggest that local societal and governmental structures play an essential role both for the baseline infection rate and the short-term and long-term reaction to the outbreak. Here we investigate how societies as a whole, and governments, in particular, modulate the dynamics of a novel epidemic using a generalisation of the SIR model, the controlled SIR model. We posit that containment measures correspond to feedback between the status of the outbreak (the daily or the cumulative number of cases and fatalities) and the reproduction factor. We present the exact phase space solution of the controlled SIR model and use it to quantify containment policies for a large number of countries in terms of short- and long-term control parameters. Furthermore, we identified for numerous countries a relationship between the number of fatalities within a fixed period before and after the peak in daily fatalities. As the number of fatalities corresponds to the number of hospitalised patients, the relationship can be used to predict the cumulative medical load, once the effectiveness of outbreak suppression policies is established with sufficient certainty.

Clozapine in the treatment of patients with autsim spectrum disorder and severe disruptive behaviours

2011 ◽  
Vol 26 (S2) ◽  
pp. 1228-1228
Author(s):  
L. Béhérec ◽  
S. Lambrey ◽  
G. Quilici ◽  
A. Rosier ◽  
B. Falissard ◽  
...  
Keyword(s):  
Antipsychotic Drugs ◽  
Autism Spectrum ◽  
Spectrum Disorder ◽  
Marginal Model ◽  
Double Blind ◽  
Before And After ◽  
Disruptive Behaviours ◽  
Extrapyramidal Effects ◽  
The Relationship

Autism spectrum disorder (ASD) is a serious childhood-onset disorder that affects all areas of development and is associated with disruptive symptoms including aggression and self injury. In ASD, risperidone and aripiprazole are the only second generation antipsychotic drugs (SGA) that have shown to decrease disruptive behaviours in controlled double-blind studies. However, some patients are not improved by these drugs. Clozapine, a SGA known to be effective to treat aggressiveness in schizophrenia, has received little attention in ASD. We conducted a retrospective analysis of the changes in disruptive for all patients with ASD who were treated with clozapine from 2002 to 2010. Disruptive behaviours were monitored during the 4 to 6 months before and after the initiation of clozapine, and long term tolerance (10 months to 7 years) was also assessed. The relationship between disruptive behaviours and periods of treatment was studied with a generalized linear marginal model. Clozapine resulted in a significant 2 fold decrease in the number of the days with aggression, a decrease of the number of psychotropic drugs and the dose of the antipsychotic drugs. The long term tolerance (white blood cell count, extrapyramidal effects) was good with the exception for a significant weight gain (of 22.3% +/- 18,2%), the occurence of metabolic syndrome in one patient and tachycardia in another patient.These results suggest that clozapine should be considered for the management of disruptive behaviours in patients with ASD not improved by first line antipsychotic drugs.

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