3,362 research outputs found
Anomalous Roughening in Experiments of Interfaces in Hele-Shaw Flows with Strong Quenched Disorder
We report experimental evidences of anomalous kinetic roughening in the
stable displacement of an oil-air interface in a Hele-Shaw cell with strong
quenched disorder. The disorder consists on a random modulation of the gap
spacing transverse to the growth direction (tracks). We have performed
experiments varying average interface velocity and gap spacing, and measured
the scaling exponents. We have obtained beta=0.50, beta*=0.25, alpha=1.0,
alpha_l=0.5, and z=2. When there is no fluid injection, the interface is driven
solely by capillary forces, and a higher value of beta around beta=0.65 is
measured. The presence of multiscaling and the particular morphology of the
interfaces, characterized by high slopes that follow a L\'evy distribution,
confirms the existence of anomalous scaling. From a detailed study of the
motion of the oil--air interface we show that the anomaly is a consequence of
different local velocities over tracks plus the coupling in the motion between
neighboring tracks. The anomaly disappears at high interface velocities, weak
capillary forces, or when the disorder is not sufficiently persistent in the
growth direction. We have also observed the absence of scaling when the
disorder is very strong or when a regular modulation of the gap spacing is
introduced.Comment: 14 pages, 17 figure
Polarized opinion states in static networks driven by limited information horizons
The widespread emergence of opinion polarization is often attributed to the rise of social media and the internet. These platforms can promote selective exposure, leading to the formation of echo chambers where individuals are only exposed to viewpoints that reinforce their existing beliefs. However, experimental evidence shows that exposure to opposing views through cross-cutting ties is common in both online and offline social contexts, which frequently involve long-standing personal relationships. To account for these facts, we have developed an opinion model that applies to static contact structures. In this model, an agent's influence over their neighbors depends on the similarity of their opinions. Our findings suggest that polarization can indeed emerge in such static structures and, driven by an increased narrow-mindedness, even in presence of non-negligible cross-cutting ties. Interestingly, the polarized opinion distributions generated by our model closely resemble those obtained in surveys about highly polarized issues. This has allowed us to categorize various issues based on their controversial nature, shedding light on the factors that contribute to opinion polarization
Enhancing Cricket Performance Analysis with Human Pose Estimation and Machine Learning
Cricket has a massive global following and is ranked as the second most popular sport globally, with an estimated 2.5 billion fans. Batting requires quick decisions based on ball speed, trajectory, fielder positions, etc. Recently, computer vision and machine learning techniques have gained attention as potential tools to predict cricket strokes played by batters. This study presents a cutting-edge approach to predicting batsman strokes using computer vision and machine learning. The study analyzes eight strokes: pull, cut, cover drive, straight drive, backfoot punch, on drive, flick, and sweep. The study uses the MediaPipe library to extract features from videos and several machine learning and deep learning algorithms, including random forest (RF), support vector machine, k-nearest neighbors, decision tree, linear regression, and long short-term memory to predict the strokes. The study achieves an outstanding accuracy of 99.77% using the RF algorithm, outperforming the other algorithms used in the study. The k-fold validation of the RF model is 95.0% with a standard deviation of 0.07, highlighting the potential of computer vision and machine learning techniques for predicting batsman strokes in cricket. The study’s results could help improve coaching techniques and enhance batsmen’s performance in cricket, ultimately improving the game’s overall quality
Water balance climatology under conditions of future climate scenarios in the Pantanal Nhecolândia, Brazil.
The objective of this work is to investigate the behavior of water conditions due to global warming analyzing future water availability for the Pantanal Sul Mato-grossense.(Embrapa Gado de Corte. Documentos, 216). Coordenador Roberto Giolo de Almeida. II SIGEE. Disponível em: . Acesso em: 01 dez. 2016
Heat to Electricity Conversion by a Graphene Stripe with Heavy Chiral Fermions
A conversion of thermal energy into electricity is considered in the
electrically polarized graphene stripes with zigzag edges where the heavy
chiral fermion (HCF) states are formed. The stripes are characterized by a high
electric conductance Ge and by a significant Seebeck coefficient S. The
electric current in the stripes is induced due to a non-equilibrium thermal
injection of "hot" electrons. This thermoelectric generation process might be
utilized for building of thermoelectric generators with an exceptionally high
figure of merit Z{\delta}T \simeq 100 >> 1 and with an appreciable electric
power densities \sim 1 MW/cm2.Comment: 8 pages, 3 figure
Physical Activity Characteristics across GOLD Quadrants Depend on the Questionnaire Used
BACKGROUND:The GOLD multidimensional classification of COPD severity combines the exacerbation risk with the symptom experience, for which 3 different questionnaires are permitted. This study investigated differences in physical activity (PA) in the different GOLD quadrants and patient's distribution in relation to the questionnaire used. METHODS:136 COPD patients (58±21% FEV1 predicted, 34F/102M) completed COPD assessment test (CAT), clinical COPD questionnaire (CCQ) and modified Medical Research Council (mMRC) questionnaire. Exacerbation history, spirometry and 6MWD were collected. PA was objectively measured for 2 periods of 1 week, 6 months apart, in 5 European centres; to minimise seasonal and clinical variation the average of these two periods was used for analysis. RESULTS:GOLD quadrants C+D had reduced PA compared with A+B (3824 [2976] vs. 5508 [4671] steps.d-1, p<0.0001). The choice of questionnaire yielded different patient distributions (agreement mMRC-CAT κ = 0.57; CCQ-mMRC κ = 0.71; CCQ-CAT κ = 0.72) with different clinical characteristics. PA was notably lower in patients with an mMRC score ≥2 (3430 [2537] vs. 5443 [3776] steps.d-1, p <0.001) in both the low and high risk quadrants. CONCLUSIONS:Using different questionnaires changes the patient distribution and results in different clinical characteristics. Therefore, standardization of the questionnaire used for classification is critical to allow comparison of different studies using this as an entry criterion. CLINICAL TRIAL REGISTRATION:ClinicalTrials.gov NCT01388218
Experiments of Interfacial Roughening in Hele-Shaw Flows with Weak Quenched Disorder
We have studied the kinetic roughening of an oil--air interface in a forced
imbibition experiment in a horizontal Hele--Shaw cell with quenched disorder.
Different disorder configurations, characterized by their persistence length in
the direction of growth, have been explored by varying the average interface
velocity v and the gap spacing b. Through the analysis of the rms width as a
function of time, we have measured a growth exponent beta ~= 0.5 that is almost
independent of the experimental parameters. The analysis of the roughness
exponent alpha through the power spectrum have shown different behaviors at
short (alpha_1) and long (alpha_2) length scales, separated by a crossover
wavenumber q_c. The values of the measured roughness exponents depend on
experimental parameters, but at large velocities we obtain alpha_1 ~= 1.3
independently of the disorder configuration. The dependence of the crossover
wavenumber with the experimental parameters has also been investigated,
measuring q_c ~ v^{0.47} for the shortest persistence length, in agreement with
theoretical predictions.Comment: 20 pages, 22 figure
Predictors of cost-effectiveness of selected COPD treatments in primary care: UNLOCK study protocol
Infographic: The EBJIS definition of periprosthetic joint infection:a practical guide for clinicians
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