Miracle-dz/UniFAR-FTUs huggingface dataset:
Analysis of intermodulation in thickness−shear and trapped energy resonators

Electroelastic equations containing terms up to cubic in the small mechanical displacement field, but no higher than linear in the electric variables, are applied in the analysis of intermodulation in rotated Y−cut quartz oscillators. Both pure thickness−shear vibrators and essentially thickness−shear trapped energy resonators are treated. In the linear part of the analysis of the trapped energy resonator, a closed−form asymptotic expression for the frequency wavenumber dispersion relation for the fundamental and odd overtone thickness−shear branches near cutoff is obtained from the three−dimensional linear equations. Lumped parameter representations of the solutions, which are valid in the vicinity of a resonance, are presented for the linear and nonlinear portions of both the pure thickness−shear and trapped energy thickness−shear problems. The influence of the driving and detecting circuitry is included and, in particular, in each case the relation between the intermodulation and driving voltage is obt.
Long-Term Effects of Mountain Hiking vs. Forest Therapy on Physical and Mental Health of Couples: A Randomized Controlled Trial

Highlights What are the main findings? Highly functioning adults with a sedentary lifestyle benefit physically and mentally from forest therapy and mountain hiking. Women predominantly benefited highly from mountain hiking regarding hemopoietic system and aerobic capacity. Both genders profited mentally from contact with nature. What is the implication of the main finding? Forest therapy and mountain hiking could be safe and health-promoting interventions for high-functioning adults with a sedentary lifestyle and could be applied in primary prevention as well as in secondary prevention. Abstract Background: Lifelong physical activity is related to longer health span, which is reflected at an individual level, and is of substantial socioeconomic relevance. Sedentary lifestyles, on the other hand, pose an increasingly major public health problem. In addition, the COVID-19 pandemic had a negative impact on activity levels and well-being. Previous research indicates that contact with nature might improve exercise levels as well as well-being. Methods: This randomized, controlled clinical trial (ANKER-study) investigated the effects of two types of nature-based therapies (forest therapy and mountain hiking) in couples (FTG: n = 23; HG: n = 22;) with a sedentary or inactive lifestyle on health-related quality of life, relationship quality and other psychological and physiological parameters. Results: The results of this study displayed that healthy and highly functioning women and men with sedentary lifestyles mentally benefit from contact with nature (quality of life, satisfaction with life, mood, internal and external health-related control beliefs). The gender-specific effect on women is most visible in the physiological outcomes (hemopoietic system, aerobic capacity, skeletal muscle mass and hydration) of mountain hiking. Men and women showed small improvements in blood pressure as a result of the interventions. Conclusions: The ANKER-study provides a method for valid comparison of forest therapy interventions for the first time. Regarding the COVID-19 pandemic, the nature-based intervention presented could offer a multimodal contribution to maintaining a more active lifestyle, further contact with nature that affects peoples physical as well as mental health, and an improvement in social interaction.
Silver/reduced graphene oxide nanocomposite materials synthesized via a green molecular level mixing

The fabrication of nano reinforced metal matrix composites (MMCs) is scientifically essential to further upgrade the thermal, electrical, and mechanical properties of current MMCs. Here, we present a green molecular mixing (MLM) of silver (Ag) and graphene (G) to overcome these challenges. Experimental results show that the green MLM allows to homogeneously mix 3 vol. % of G as observed with traditional MLM while adding a control on the oxidation steps. Metal and GO reductions can be precisely control by varying the solution temperature. Highly thermal conductivity and strong elastic modulus nanocomposites are fabricated making it an eco-friendlier mixing process.
Taming multiple valency with density functionals: A case study of defective ceria

Modeling multiple-valence compounds using density-functional theory has long been considered a formidable task due to the role that strong electronic correlations play in these systems. We show that, in the case of defective ceria, the main effect of these correlations is to produce a multitude of metastable low-energy states among which the one displaying the correct valence of cerium is the most stable. This ground state may be difficult to access in practice and it has in fact so far escaped a proper identification. The introduction of a Hubbard-U term in the energy functional stabilizes the physical ground state and makes it easily accessible to routine calculations. When this contribution is defined in terms of maximally localized Wannier functions, the calculated energies and structural properties are independent of the value of the parameter U.
GENERALIZATIONS OF STURM--PICONE THEOREM FOR SECOND-ORDER NONLINEAR DIFFERENTIAL EQUATIONS

The goal of this paper is to show a generalization to Sturm--Picone theorem for a pair of second-order nonlinear differential equations (p_1(t)x'(t))'+ q_1(t)f_{1}(x(t))=0. (p_2(t)y'(t))'+ q_2(t)f_{2}(y(t))=0, ,t_1<t<t_2. This work generalizes well-known comparison theorems [C. Sturm, J. Math.Pures. Appl. 1 (1836), 106--186; M. Picone, Ann. Scoula\,Norm. \,Sup. \,Pisa, 11 (1909),39; W. Leighton, Proc. Amer. Math. Soc.13 (1962), 603--610], which play a key role in the qualitative behavior of solutions. We establish the generalization to a pair of nonlinear singular differential equations and elliptic partial differential equations also. We show generalization via the quadratic functionals associated to the above pair of equations. The celebrated Sturm--Picone theorem for a pair of linear differential equations turns out to be a particular case of our result. We also use these comparison theorems to ensure the oscillatory as well as nonoscillatory behavior of solutions for a class of nonlinear equations.
A COMPARISON OF TREE-BASED REGRESSION MODELS FOR SOIL MOISTURE ESTIMATION USING SAR DATA

Abstract. Soil moisture content plays a pivotal role in biomass development of vegetation coverage at various growth stages. Moisture content of the soil is considered as a crucial parameter for agricultural studies which directly leads to higher fertility rate. Remote sensing techniques, specifically Synthetic Aperture Radar (SAR) sensors, provides suitable opportunity for continuous soil moisture monitoring at various spatial and temporal resolutions. In this study, field campaigns conducted to measure soil surface parameters, including soil moisture and roughness, synchronized with Sentinel-1 pass over an agricultural region near Mohammadshahr, Iran. Fieldwork for soil moisture sampling have done during plants’ (canola and winter wheat) growth stages. The Gradient Boosted Regression Tree (GBRT), eXtreme Gradient Boosted (XGB), and Random Forest (RF) machine learning algorithms were employed to model the relationship between the ground measured soil moisture and polarimetric SAR derived features from Sentinel-1 imageries. The results showed promising results obtained for soil moisture estimation using the dual-polarized SAR dataset over crop-covered agricultural fields with R2 = 0.95 and RMSE = 0.023 m3 m−3 using the GBRT regression model.
On the velocity dependence of the interstellar Na I/Ca II ratio.

The correlation noted by Routly and Spitzer (1952) between the ratio of the column densities of interstellar Na I and Ca II and radial velocity in the spectra of 21 early-type stars is reinvestigated on the basis of more recent data for 64 stars. The original result is confirmed, and it is further demonstrated that the low values of Na I/Ca II are associated with large peculiar velocities relative to the local standard of rest. It is proposed that the bulk of the high-velocity components can be interpreted as old supernova remnants. A statistical analysis of the distribution with velocity of interstellar Ca II K lines observed by Adams (1949) in the directions of some 300 early-type stars is found to be consistent with this hypothesis.
Vorticity generated by pure capillary waves

Capillary waves, like other surface waves on water, generate a rectified, or time-averaged, vorticity field extending beyond the oscillatory (Stokes) layer at the surface. This vorticity field ω is particularly interesting in relation to the parasitic capillary waves found on the forward slopes of steep gravity waves. Longuet-Higgins (1992) suggested that the rectified vorticity from the parasitic capillaries might contribute significantly to the vorticity observed beneath the crest of the gravity wave. The basic calculations by Longuet-Higgins (1992) were only of the horizontally averaged values of ω. Here we extend his theory by calculating, for pure capillary waves, the space variation of ω, to second order in the steepness of the capillary waves. Thus, the vorticity, and hence velocity, fields are calculated in the oscillatory Stokes layer and just beyond it, to the second order. Good agreement is found both with numerical simulations and with experimental measurements.
Ethnomathematical and Mathematical Connections Activated by a Teacher in Mathematical Problems Posing and Solving

Background : Connections are essential for understanding concepts, but difficulties have been evidenced in connecting representations and meanings of concepts and creating contextualised mathematical problems by teachers and students. Objective : Therefore, ethnomathematical and mathematical connections were analysed in a teacher’s mathematical activity when posing and solving mathematical problems. Design : The methodology was qualitative-ethnographic, developed in a workshop done in stages. Setting and participants : An indigenous Mokaná teacher from Sibarco was selected. Data collection and analysis : Semi-structured interviews were conducted in the workshop
Characteristics of a trailing-edge flow with turbulent boundary-layer separation

Experimental techniques, including flying-hot-wire anemometry, have been used to determine the pressure and velocity characteristics of a flow designed to simulate the trailing-edge region of an airfoil at high angle of attack. Emphasis is placed on the region of recirculating flow and on the downstream wake. It is shown that the effect of this recirculation is large even though the details of the flow within it may be unimportant. Normal stresses and cross-stream pressure gradients are important immediately upstream and downstream of the recirculating flow and are associated with strong streamline curvature. The relative importance of the terms in the transport equations for mean momentum and turbulence energy are quantified and the implications for procedures which solve potential-flow and boundary-layer equations and for alternative calculation methods are discussed.
Coaxial laser cladding of cobalt-base alloy StelliteTM 6 on gray cast iron/investigations on friction, wear versus commercial brake pad, and corrosion characteristics

Environmental legislation and the electrification of vehicles place increased requirements on brake disks in terms of wear and corrosion resistance. Departing from a preliminary study, the present investigation examined the friction and wear behavior as well as the corrosion properties of Stellite™ 6 coatings on gray cast iron, which were deposited by laser cladding. The friction and wear experiments were conducted on a pin-on-disk tribometer at contact pressures of 1.0 and 2.0 MPa as well as rotation speeds of 0.2, 0.4, 0.6, 0.8, and 2.0 m/s. The pins are manufactured from an automotive semi-metallic brake pad. The friction behavior of gray cast iron and Stellite™ 6 coatings is similar under changing test conditions. The tribological behavior is strongly influenced by the microstructural and mechanical properties of the coatings and the brake pad material. A third body layer of contact patches is formed on Stellite™ 6, which mainly consists of brake pad components. The transformation of the Co-matrix (fcc → hcp), subsurface fatigue, and tribo-oxidation are the main wear mechanism for Stellite™ 6. The electrochemical characteristics were analyzed by potentiodynamic polarization, and the corrosion rate was determined with Tafel plots in 3.5% NaCl solution, respectively. Compared to gray cast iron, Stellite™ 6 coatings have a pronounced corrosion resistance due to the formation of a protective passive layer of Co and Cr oxides. This corrosion resistance is mainly influenced by the microstructure. The corrosion rate of the coatings increases in parallel with the Fe dilution.
A GENERAL ANALYSIS OF OPTICAL, INFRARED, AND MICROWAVE MASER OSCILLATOR EMISSION

A generalization is presented of equations governing coherent emission from quantum mechanical amplifiers (microwave, infrared, and optical masers) using either electric or magnetic dipole transitions. It was found that an amplitude modulation of the output is to be expected from all maser oscillators excepting those in which excited atoms are supplied at a notably greater rate than the depopulation rate caused by coherent induced emission. The analysis also suggests that an energy population inversion of electric dipole moments can be performed using coherent light sources in the same manner as with magnetic dipole moments. It appears that modulation of infrared or optical masers may be easily accomplished by varying the population of excited states through control of the pumping energy. (B.O.G.)
Utility of the Teacher Behavior Checklist beyond Psychology Majors: Replication with Brazilian Physical Education Students

The Teacher Behavior Checklist (TBC) is a worldwide valued instrument to measure teachers’ performance. Nonetheless, the studies about TBC in Brazil are still scarce, with samples mainly composed of psychology and civil engineering students. The aim of this study was to replicate the research by Keeley et al. (2010) to evaluate the psychometric properties of the Brazilian version of the TBC with a new sample. Participants were 107 undergraduates from physical education courses from a Brazilian public university. Participants used the TBC to evaluate three types of teachers: the worst they had ever had, a regular one, and the best one. The order of evaluation of teacher types did not interfere with the response patterns, but as expected, statistically significant differences were found among the three types of teachers. Additionally, the two-factor model of the TBC was confirmed through Confirmatory Factor Analysis, providing additional evidence of construct validity. However evidence to advocate in favor of a one-factor solution was also found. McDonald’s Omega results provided evidence of reliability. These findings support the use of TBC in the formative evaluation of teachersin Brazil.
Exploring intra-party democracy and political finance in Pakistan: The case of effectiveness of mainstream political parties

This article explores the effectiveness of political parties in relation to political finance and intra-party democracy in Pakistan. The aim of the article is to offer an objective understanding of these variables and suggest a model for the effectiveness of political parties. Primary data was collected from a sample of 1000 respondents from eight different but politically relevant parties. The respondents have diverse socio-political backgrounds and positions in parties hailing from all the provinces of Pakistan and Azad Jammu & Kashmir – a semi-autonomous territory under the administration of Pakistan. The instrument was developed and its validity and reliability were ensured. For empirical verification, extensive statistical tests were carried out, including validity and reliability analysis, standard regression and correlation, to test the assumptions of the research. Statistical analysis established that the independent variables are very significant in explaining the relationship with the dependent variable. Overall, most of the political parties are not internally democratic as they do not follow laid-down democratic processes in electing leadership and candidate selection, the findings revealed. Political parties are monopolized by personalities with weak organization and are institutionally fragile and compromise on their ideological foundation by preferring political expediency while decision making. Likewise, parties also rank poor in political finance as they rarely follow legal and administrative requirements laid down by the Election Commission of Pakistan on political finance. This has a direct bearing upon party effectiveness, as poor intraparty and weak political finance hinder party development as effective institutions aiming to aggregate the interests of the masses. The parties must ensure inclusiveness in choice making, build formal democratic decision-making structures and reinforce the key procedures for political financing. Moreover, political parties should be transparent and responsive towards democratic values and institutional practices to increase their effectiveness.
Experiments on heat-stabilized laminar boundary layers in water

There has been much recent interest in the stabilization of water boundary layers by wall heating. Calculations based upon linear stability theory have predicted transition Reynolds numbers as high as 200 million for a zero pressure gradient boundary layer over a heated wall. The experiment described in this paper was intended to investigate these predictions. The test boundary layer develops on the inside surface of a cylindrical tube which is 0·1 m in diameter and 6·1 m in length. The displacement thickness is small relative to the tube radius under all conditions of interest. The tube is heated by electrical heaters on the outside wall. The location of transition is determined by flush-mounted hot-film probes, or by flow visualization at the tube exit. A transition Reynolds number of 15 million has been obtained without heat, which shows that free-stream turbulence and other perturbations are well controlled. A transition Reynolds number of 47 million has been obtained with an 8 °C wall overheat. However, as temperature is further increased there are no additional increases in transition Reynolds number, which is in contradiction to the theory. Several possible reasons for the discrepancy between theory and experiment have been investigated.
Entropy-based design approach of threshold alluvial channels

A new approach has been developed for designing the shape and dimensions of the cross section of a straight threshold channel based on the concepts of entropy and probability. A formula for the lateral distribution of transverse slopes, and hence the cross-sectional bank profile, was derived by the entropy-maximisation principle and the calculus of variations. The bank profile is a new type of simple parabolic curve. The results of numerical experiments based on the approach of boundary shear stress distribution support the conclusion that the entropy-based channel bank profile is at threshold. Bank profile equations are coupled with an appropriate frictional relationship to obtain a new design method. Channel dimensions and bank profiles predicted by this method are compared with those given by other design methods. The predicted channel dimensions are in reasonable agreement with laboratory experimental data.
Early Years Physical Activity and Motor Skills Intervention—A Feasibility Study to Evaluate an Existing Training Programme for Early Years Educators

A lack of fundamental motor skills (FMS) in the early years can lead to lower engagement with physical activity (PA), and track into adulthood. This study aimed to test the feasibility of an existing intervention for Early Years Educators (“Educators”) designed to increase knowledge, confidence and the ability to increase PA and FMS of children in a deprived area of England. Non-randomised design with wait-list control. Sixty-seven settings in Middlesbrough, North East England were invited. Recruitment target: 10 settings, 2 Educators per setting, four children per Educator. Intervention: one-day training course “Physical Literacy in the Early Years”, an age-appropriate theoretical and practical training course to support the development of physical literacy. Primary outcomes: recruitment, retention, acceptability of intervention and outcome measures. Secondary outcomes: change in Educators’ knowledge, intentions and behaviour, and change in children’s BMI z-score, PA and FMS. Eight settings were recruited; all Intervention Educators completed the training. Six settings participated at follow-up (four Intervention, two Control). The target for Educator recruitment was met (two per setting, total n = 16). Questionnaires were completed by 80% of Intervention Educators at baseline, 20% at follow-up. Control Educators completed zero questionnaires. No Educators took part in a process evaluation interview. Forty-eight children participated at baseline, 28 at follow-up. The intervention was deemed acceptable. The recruitment, retention and acceptability of measurements were insufficient to recommend proceeding. Additional qualitative work is needed to understand and surmount the challenges posed by the implementation of the trial.
The Cooling Rate of a Liquid Shell in Titan's Interior

Models describing the evolution of the primordial liquid layer in Titan's interior are presented using parameterized models. These models incorporate recent experimental data on the ammonia water phase diagram in the range [100 MPa–1 GPa] and recently published creep laws for ice I. Just after accretion, the thickening of the outer ice I layer is achieved by conduction. It seems likely that this outer shell becomes thick enough for solid-state convection to start about 200 myr after accretion. The temperature in the ice I outer shell cannot be larger than the melting temperature of the NH3–H2O liquid at the interface between the liquid layer and the ice I shell. As a result, the temperature in the ice I layer is much smaller than the melting temperature for ice I and the viscosity is too large to yield very vigorous convection and rapid cooling of the satellite. Moreover, this study suggests that the decay of the radioactive element content in the silicate rich inner core of the satellite keeps heating the core for 3 byr after the core overturn. If present after accretion, a liquid layer is likely to exist at the present time in Titan's interior. The thickness of the liquid layer does not vary much with time and its value depends only on the initial amount of ammonia.