Miracle-dz/UniFAR-FTUs huggingface dataset:
Motives for using social networks and social network addiction in a time of pandemic

The lockdown situation caused by COVID-19 has increased the use of social networks, which could, in turn, increase social networks addiction. This research consists of two integrated studies aimed at (1) developing and validating the Social Networks Motives Scale (SN-MotiveS) and (2) examining the relationships between the frequency of use of social networks and the motives for why individuals use social networks with social networks addiction, as well as the evolution of these variables over time before (through a retrospective assessment), during, and after lockdown. During lockdown, an online questionnaire was distributed to a sample of 482 participants (Study 1). After lockdown, 114 participants from Study 1 completed a second online questionnaire, forming a longitudinal study (Study 2). Study 1 showed a robust fit for the multifactorial structure of the SN-MotiveS with four factors (socialization, escapism, prosocial behavior, and self-presentation), supporting the external validity of the scale, and the expected correlation patterns were found with social networks frequency of use, abuse, and addiction. Study 2 showed that all the motives increased during lockdown except for self-presentation, whereas after lockdown only prosocial behavior and employment (added in Study 2) decreased significantly. Moreover, the self-presentation and escapism motives acted as mediators in the relationship between social networks frequency of use and social networks addiction. This research provides a reliable instrument to measure the motives for using social networks both during a pandemic and in normal times. In addition, it highlights the importance of paying special attention to escapism motives for predicting social networks addiction in periods of lockdown.
Causal Input/Output Representation of 2D Systems in the Behavioral Approach

In this paper the concept of causal input/output representation of two-dimensional (2D) systems in the behavioral approach is introduced. These representations provide an interesting connection between classical 2D systems theory and 2D systems theory in the behavioral approach. Some characterizations of such representations are presented. Finally, a technique that allows us to obtain causal input/output representations is proposed.
Random lasing in multimode diode-pumped graded-index fiber based on artificial Rayleigh scattering in fs-inscribed random structure

We study an opportunity to obtain low-threshold random Raman lasing in multimode diode-pumped graded-index (GRIN) fiber with enhanced backscattering in artificial fs-inscribed random structure. Proof-of-principle experiments have been performed with a 1-km multimode GRIN fiber of 100-µm core directly pumped by three fiber-combined high-power 940- nm LDs. The laser has half-open all-fiber cavity consisting of highly-reflective FBG which is UV-inscribed in GRIN fiber near the LD input and artificial random reflector near its output end. Different types of random structures were formed by the point-by-point femtosecond-pulse technique in the near-axis area of GRIN fiber core (different pitch, length and transverse profile). Comparison of their lasing properties in the multimode diode-pumped GRIN fiber has been performed. The lowest threshold of ~140 W and the highest output power of 6.2 W (at ~180 W pumping) with the beam quality M2~3.3 is achieved for 2D structure. It is shown that the quality is improved to M2~2.4 for 1D structure at the expense of slight reduction in output power (5.5 W).
Short wavelength optical anisotropy in CaF 2 caused by exciton dispersion

Based on exact symmetry considerations one can show that a cubic system is always optically isotropic. Nevertheless even a per- fectly cubic crystal such as CaF2 can show small optical anisotropy when interacting with light. Resolving this seeming contradiction leads to a phenomenon called spatial dispersion, which is an enhancement of op- tical anisotropy. While the initial tiny anisotropy is caused by the symme- try breaking of light, the enhancement that makes the effect observable is provided by the vicinity of a strong absorption. In semiconductors such an absorption is mainly given by the band gap but in an ionic crystal such as CaF2 the bound electron-hole pair, a deep excitonic two-particle bound state, is an additional strong absorption causing response func- tions to diverge as (v2v 0) 21 in its vicinity, where v 0 is the bound state energy. We show that the exciton dispersion is able to explain in all details the optical anisotropy observed in CaF2 including the spatial- dispersion-induced birefringence, the so-called ''intrinsic birefringence. '' As opposed to normal birefringence, the effect in CaF2 does not show up at large wavelengths and has seven optical axes instead of one. © 2003
Direct laser writing of 3D micro/nanostructures on opaque surfaces

Spectra of fields for applications of polymeric 3D micro/nanostructures is rapidly widening thus demanding the development of versatile precise and efficient fabrication methods that can be used to process a variety of materials and could be implemented to form tiny devices on a variety of surfaces without influencing their structural quality. We present the latest results obtained using laser lithography approach: 3D polymeric structures with submicrometer spatial resolution on different opaque surfaces such as semiconductors (Si) and various metals (Cr, Al, Fe, Ti). The photostructuring was performed using a range of photosensitive materials such as acrylate based AKRE23, acrylated biodegradable PEG-DA-258, epoxy based mr-NIL 6000, hybrid organic-inorganic SZ2080 and Ormocore b59.
The Influence of Drying on the Aeolian Transport of River‐Sourced Sand

Transgression and regression of water levels (stages) have impacted the evolution of aeolian landforms and sedimentary deposits throughout geologic history. We studied this phenomenon over a 5‐day period of reduced flow on the Colorado River in Grand Canyon National Park, AZ, USA, in March 2021. These transient low flows exposed river‐channel sand deposits to the air, causing progressive desiccation (drying) and thereby making these deposits susceptible to aeolian transport. We measured aeolian threshold friction velocities (u*t) for sand saltation and PM10 dust emissions, as well as other characteristics, on a subaerially exposed sandbar and downwind aeolian dunefield during each day of the low river flow. The sandbar transitioned from supply‐limited to transport‐limited aeolian sediment transport conditions during the regression in river water stage. A possible tipping point between the two transport conditions occurred approximately 48 hr after the drop in river flow. The empirically measured u*t decreased as the sandbar sediment dried with increased subaerial exposure time. Theoretical estimates and empirical measurements of u*t corresponded closely on the aeolian dunefield and on the sandbar when it was drier during the third and fourth day of the experiment. Eighty‐seven percent of the variability in u*t was explained by empirical models that provide practical estimates of aeolian transport potential of subaerial river sediment deposits using monitoring data that are commonly available in this and other river systems. The work provides theoretical insight into the response of aeolian processes to sediment supply changes driven by periods of anthropogenic activity, drought, and climate change.
Study on the Optimum Virtual Topology for MPI based Parallel Conformal FDTD Algorithm on PC Clusters

In this paper, the concept of "the optimum virtual topology" for MPI based Parallel FDTD is firstly presented. The Parallel Conformal FDTD code developed by our group earlier was run on a PC cluster with high performance to analyze a new type of PBG microstrip filter structure and a new type of base station antenna. Taking them as examples, the influence of virtual topology schemes on parallel performance of Parallel FDTD is studied in detail. Finally the general rules are presented on how to obtain the highest efficiency of Parallel FDTD algorithm by optimizing MPI virtual topology.
The Stability of Molecular Clouds

A local instability analysis of a self-gravitating partially ionized, warm, magnetized gas is used to study the stability of molecular clouds. It is found that wave propagation is possible for wavelengths longer than the critical frictional damping scale in clouds, as long as the magnetic and thermal energy densities exceed the gravitational energy density. The analysis is extended to the case in which a background spectrum of Alfven waves supports the cloud against global collapse. It is shown that the steepness of the wave spectrum is as important as the overall magnetization of the cloud in determining which modes become unstable. It is found that, for a wide range of wave spectra, the largest scales in a cloud can be supported against global collapse, while for a band of smaller wavelengths, gravitational collapse may occur. 30 refs.
Edge turbulence and flows in the presence of resonant magnetic perturbations on MAST

The impact of resonant magnetic perturbations (RMPs) on the edge of MAST L-mode plasmas is studied using a mid-plane reciprocating probe equipped with a Gundestrup probe head. A strong impact on the characteristics of the ion saturation current fluctuations is observed just inside the separatrix, with a broadening of the power spectrum and an asymmetrization of the probability distribution functions towards non-Gaussian shapes. No major effect is found in the scrape-off layer (SOL). Floating potential measurements are used to evaluate the modification of the plasma potential profiles. The radial electric field profile flattens when RMPs are applied, leading to a theoretically expected increase in Er inside the separatrix and a decrease in the SOL. A consistent change is observed on the perpendicular and parallel flows which tend to increase inside the separatrix. In contrast, in the SOL, a braking of the rotation is observed with the application of RMPs. All these effects occur only above a threshold in the amplitude of the current applied in the RMP coils and are not toroidally localized.
Analysis of grain-boundary effects on the electrical properties of Pb(Zr,Ti)O3 thin films

The effects of grain boundaries on the characteristics of Pb(Zr,Ti)O3 (PZT) thin films were investigated by locating the top electrode within grain, on the line boundary, or on the grain-boundary intersection in a controlled manner. It turned out that, when there was no grain boundary in the area measured, excellent ferroelectric and electrical performance was obtained. On the other hand, serious degradation was observed in terms of polarization, leakage current, breakdown field, and fatigue characteristics when grain boundaries were included in the area studied. It was found that degradation of PZT thin films was closely correlated with the length of grain boundary in the area measured.
A street‐level perspective on government transparency and regulatory performance: Does relational distance matter?

This study investigates the extent to which inspectors perceive government transparency as impacting regulatory performance. It theorizes that when inspectors perceive an increase in transparency, they find that the perceived relational distance between themselves and their inspectees rises and this, subsequently, increases regulatory performance. The findings from a survey among Netherlands Food and Consumer Product Safety Authority inspectors (n = 466) confirm that inspectors view an increase in transparency as enhancing regulatory performance. This study further investigates this mechanism by comparing two divisions with different levels of factual relational distance (i.e., frequency of inspector–inspectee interactions). The findings reveal that only in the division with small factual relational distance does perceived relational distance mediate the effect of transparency on regulatory performance. More specifically, in divisions with small factual relational distance, more perceived transparency increases perceived relational distance; this in turn, increases perceived regulatory performance.
The Effect of Government Teacher Certification on Teaching Performance: Certified vs uncertified

The Indonesian government encourages all teachers to be certified in the hope of improving teachers’ performance. The purpose of this study was to explore the effect of teacher certification on teacher performance in the northern Toraja region. Utilizing quantitative methods approach, this study randomly sampled 94 students and teachers. The students were subject to a distribution instrument to evaluate the performance of certified and uncertified teachers. To support the quantitative data a short interview was conducted to 10 randomly selected teachers regarding their perception of the relation between certification and teacher performance. The collected data were subjected to validation test, reliability test and simple linear regression test. The results show that there are 33.75% students strongly disagree with the performance of certified teachers who have been certified but there are 65.85% who agree and strongly agree with the performance of teachers who have been certified. While teachers who have not been certified 35.16% strongly disagree and disagree with the performance of teachers who have not been certified and only 53.88% agree and strongly agree. Conclusively, there is an effect of teacher certification on teaching performance although not very significant between certified and uncertified teachers. Some recommendations for the government regarding the current practice of teacher certification are included.
Dissipative Asynchronous Filtering for Networked Fuzzy Markov Jumping Systems With Quantized Measurements and Packet Dropouts

This article is concerned with the dissipative asynchronous filtering for a class of networked Takagi–Sugeno fuzzy Markov jumping systems subject to packet dropouts. The system measurements are quantized with a logarithmic quantizer and a Bernoulli model is introduced to deal with the packet dropouts occurred in the communication channel from the quantizer to the filter. Both the quantizer and the filter are mode dependent, and their modes are asynchronous with those of the physical plant, governed by two hidden Markov models. Based on the mode- and fuzzy-rule-dependent Lyapunov function method, a sufficient condition is derived such that the resultant filtering error system is stochastically stable in the mean-square sense and strictly dissipative. The slack-matrix approach and Finsler’s lemma are further exploited to design suitable dissipative filters if a set of linear matrix inequalities are feasible. Finally, two examples including a tunnel-diode circuit system are taken to demonstrate the efficiency of our proposed results.
Hysteretic Friction of a Sliding Rubber Element

Friction, especially friction of elastomers, can cause acoustic problems like noise, squeal and comfort drawbacks like vibrations and wear. Therefore, rubber friction affects the function of many products in technical applications, e.g. seals, belts and tires. It can be classified according to different physical phenomena like adhesion, hysteresis, cohesion and viscous friction, see [3]. The topic of this paper is hysteresis friction of rubber that is caused by the energy dissipation due to internal material damping during the process of deformation. The deformation itself occurs during the sliding of a rubber element across the micro‐scaled asperities of a rough surface. In this paper, the sliding process of a rubber element over real surfaces is simulated in time domain and compared to experiments. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Competency Upgrading for Coaches of Depok City: Internalization of Basic Characters in Sports

Based on data from the Research and Development Division of the Depok City KONI, until 2020 there were only 43.1% of Depok City coaches had sports branch certificates as legathe lization of competent coaches. This competency upgrading training aims to provide training on character competencies that are not usually discussed specifically in sports so far. The training participants are the coaches of Depok City and its surroundings who have handled 125 junior or beginner-level athletes. The training material contains basic characteristics (honesty, discipline, and cooperation) that sports coaches need to toer to internalize positive values ​​so that the coach can become a "character role model" for his athletes. Based on the results of the training, it is known that most of the coaches have high / good interest, understanding, and analysis ability in participating in this competency upgrading training (interest is 99.2%, understanding is 80%, and alyticallity is 84%). There were no differences in coaches' interests, understanding, and analysis ability in terms of gender, age, and training experience. The results of this training provide important feedback for conducting competency upgrading training in Depok City in the future.
Fibonacci Numbers with the Lehmer Property

Let φ(n) be the Euler function of the positive integer n. Clearly, φ(n) = n − 1 if n is a prime. Lehmer [9] (see also B37 in [7]) conjectured that if φ(n) |n−1, then n is prime. To this day, no counterexample to this conjecture (and no proof of it either) has been found. Let us say that n has the Lehmer property if n is composite and φ(n) |n−1. Thus, Lehmer’s conjecture is that there is no number with the Lehmer property. Pomerance (see [14], [15]) showed that if L(x) denotes the number of numbers n ≤ x with the Lehmer property then the estimate L(x) = O(x(log x)(log log x))
Asynchronies during invasive mechanical ventilation: narrative review and update

Invasive mechanical ventilation is a frequent therapy in critically ill patients in critical care units. To achieve favorable outcomes, patient and ventilator interaction must be adequate. However, many clinical situations could attempt against this principle and generate a mismatch between these two actors. These asynchronies can lead the patient to worst outcomes; that is why it is vital to recognize and treat these entities as soon as possible. Early detection and recognition of the different asynchronies could favor the reduction of the days of mechanical ventilation, the days of hospital stay, and intensive care and improve clinical results.
Linear optimal control applied to instabilities in spatially developing boundary layers

The work presented extends previous research on linear controllers in temporal channel flow to spatially evolving boundary layer flow. The flows studied are those on an infinite swept wedge described by the Falkner–Skan–Cooke (FSC) velocity profiles, including the special case of the flow over a flat plate. These velocity profiles are used as the base flow in the Orr–Sommerfeld–Squire equations to compute the optimal feedback control through blowing and suction at the wall utilizing linear optimal control theory. The control is applied to a parallel FSC flow with unstable perturbations. Through an eigenvalue analysis and direct numerical simulations (DNS), it is shown that instabilities are stabilized by the controller in the parallel case. The localization of the convolution kernels for control is also shown for the FSC profiles. Assuming that non-parallel effects are small a technique is developed to apply the same controllers to a DNS of a spatially evolving flow. The performance of these controllers is tested in a Blasius flow with both a Tollmien–Schlichting (TS) wave and an optimal spatial transiently growing perturbation. It is demonstrated that TS waves are stabilized and that transient growth is lowered by the controller. Then the control is also applied to a spatial FSC flow with unstable perturbations leading to saturated cross-flow vortices in the uncontrolled case. It is demonstrated that the linear controller successfully inhibits the growth of the cross-flow vortices to a saturated level and thereby delays the possibility of transition through secondary instabilities. It is also demonstrated that the controller works for relatively high levels of nonlinearity, and for stationary as well as time-varying perturbations.
Cu2ZnSnS4 Thin Films Annealed in H2S Atmosphere for Solar Cell Absorber Prepared by Pulsed Laser Deposition

Cu2ZnSnS4 (CZTS) precursors were prepared by pulsed laser deposition while controlling the energy density to eliminate grains of Cu–Sn–S compounds. The precursor prepared with an energy density of 0.7 J/cm2 was flat and of better quality than the precursor prepared with an energy density of 1.5 J/cm2. The precursors were annealed in N2+H2S (5%) atmosphere. As a result of annealing, the decrease of the compositional ratio of sulfur was suppressed and the films became nearly stoichiometric. Some peaks in the an X-ray diffraction pattern of thin films are attributed to (112), (220), (312), and (200) planes of CZTS. The direct band-gap energy of the film annealed at 500 °C was about 1.5 eV, which is very close to the optimum value for a solar-cell absorber, and hence was used for a solar cell. The CZTS thin film solar cell with an active area of 0.12 cm2 showed an open-circuit voltage of 336 mV, a short-circuit current of 6.53 mA/cm2, a fill factor of 0.46, and a conversion efficiency of 0.64%.
Estimation of Soil Freeze Depth in Typical Snowy Regions Using Reanalysis Dataset: A Case Study in Heilongjiang Province, China

Soil freeze depth variations greatly affect energy exchange, carbon exchange, ecosystem diversity, and the water cycle. Given the importance of these processes, obtaining freeze depth data over large scales is an important focus of research. This paper presents a simple empirical algorithm to estimate the maximum seasonally frozen depth (MSFD) of seasonally frozen ground (SFG) in snowy regions. First, the potential influences of driving factors on the MSFD variations were quantified in the baseline period (1981–2010) based on the 26 meteorological stations within and around the SFG region of Heilongjiang province. The three variables that contributed more than 10% to MSFD variations (i.e., air freezing index, annual mean snow depth, and snow cover days) were considered in the analysis. A simple multiple linear regression to estimate soil freeze depth was fitted (1981–2010) and verified (1975–1980 and 2011–2014) using ground station observations. Compared with the commonly used simplified Stefan solution, this multiple linear regression produced superior freeze depth estimations, with the mean absolute error and root mean square error of the station average reduced by over 20%. By utilizing this empirical algorithm and the ERA5-Land reanalysis dataset, the multi-year average MSFD (1981–2010) was 132 cm, ranging from 52 cm to 186 cm, and MSFD anomaly exhibited a significant decreasing trend, at a rate of −0.38 cm/decade or a net change of −28.14 cm from 1950–2021. This study provided a practical approach to model the soil freeze depth of SFG over a large scale in snowy regions and emphasized the importance of considering snow cover variables in analyzing and estimating soil freeze depth.