Miracle-dz/UniFAR-FTUs huggingface dataset:
Breaking and Fixing Virtual Channels: Domino Attack and Donner

—Payment channel networks (PCNs) mitigate the scalability issues of current decentralized cryptocurrencies. They allow for arbitrarily many payments between users connected through a path of intermediate payment channels, while requiring interacting with the blockchain only to open and close the chan- nels. Unfortunately, PCNs are (i) tailored to payments, excluding more complex smart contract functionalities, such as the oracle- enabling Discreet Log Contracts and (ii) their need for active participation from intermediaries may make payments unreliable, slower, expensive, and privacy-invasive. Virtual channels are among the most promising techniques to mitigate these issues, allowing two endpoints of a path to create a direct channel over the intermediaries without any interaction with the blockchain. After such a virtual channel is constructed, (i) the endpoints can use this direct channel for applications other than payments and (ii) the intermediaries are no longer involved in updates. In this work, we first introduce the Domino attack, a new DoS/griefing style attack that leverages virtual channels to destruct the PCN itself and is inherent to the design adopted by the existing Bitcoin-compatible virtual channels. We then demonstrate its severity by a quantitative analysis on a snapshot of the Lightning Network (LN), the most widely deployed PCN at present. We finally discuss other serious drawbacks of existing virtual channel designs, such as the support for only a single intermediary, a latency and blockchain overhead linear in the path length, or a non-constant storage overhead per user. We then present Donner, the first virtual channel construction that overcomes the shortcomings above, by relying on a novel design paradigm. We formally define and prove security and privacy properties in the Universal Composability framework. Our evaluation shows that Donner is efficient, reduces the on- chain number of transactions for disputes from linear in the path length to a single one, which is the key to prevent Domino attacks, and reduces the storage overhead from logarithmic in the path length to constant. Donner is Bitcoin-compatible and can be easily integrated in the LN
The perceptual organization of noise-vocoded speech under competitive conditions.

Research using sine‐wave speech suggests that across‐formant grouping depends critically on modulation of the frequency but not the amplitude contours of the formants. The generality of this finding was explored using noise‐vocoded sentences. Sentences were filtered into six frequency bands, and the amplitude envelope of each band was used to modulate a matched noise‐band carrier (N). Bands were paired, corresponding to F1 (=N1+N2), F2 (=N3+N4), and the higher formants (F3′=N5+N6), so that the frequency contour of a formant was implied by variation in the relative amplitudes of the corresponding pair of bands. Perceptual organization was probed by presenting stimuli dichotically (F1+F2C; F2+F3′), where F2C is a competitor for F2 that listeners must resist to optimize intelligibility. F2Cs were derived from F2 by time reversing the envelopes of N3+N4. Implied frequency variation in F2C was manipulated by varying the AM depth in the constituent bands (100%‐0% of original depth) or by comodulating both bands.
Gas-liquid two-phase flow across a bank of micropillars

Adiabatic nitrogen-water two-phase flow across a bank of staggered circular micropillars, 100μm long with a diameter of 100μm and a pitch-to-diameter ratio of 1.5, was investigated experimentally for Reynolds number ranging from 5 to 50. Flow patterns, void fraction, and pressure drop were obtained, discussed, and compared to large scale as well as microchannel results. Two-phase flow patterns were determined by flow visualization, and a flow map was constructed as a function of gas and liquid superficial velocities. Significant deviations from conventional scale systems, with respect to flow patterns and trend lines, were observed. A unique flow pattern, driven by surface tension, was observed and termed bridge flow. The applicability of conventional scale models to predict the void fraction and two-phase frictional pressure drop was also assessed. Comparison with a conventional scale void fraction model revealed good agreement, but was found to be in a physically wrong form. Thus, a modified physically .
Wavelet-based modeling of spectral bidirectional reflectance distribution function data

The Bidirectional Reflectance Distribution Function (BRDF) is an important surface property, and is commonly used to describe reflected light patterns. However, the BRDF is a complex function since it has four angular degrees of freedom and also depends on the wavelength. The direct use of BRDF data set may be inefficient for scene modelling algorithms for example. Thus, models provide compression and additional functionalities like interpolation. One common way consists in fitting an analytical model to the measurements data set using an optimization technique. But this approach is usually restricted to a specific class of surfaces, to a limited angular or spectral range, and the modelling quality may strongly depends on the optimization algorithm chosen. Moreover, analytical models are unable to actually handle the BRDF dependence on wavelength. In this paper we present a new numerical model for acquired spectral BRDF to overcome these drawbacks. This model is based on a separation between the spectral and the geometrical aspect of BRDF, each of them projected into the appropriate wavelet space. After a brief introduction to BRDF, advantages of wavelets and the construction of the model are explained. Then, the performances of modelling are presented and discussed for a large collection of measured and synthetic BRDF data sets. At last, the robustness of the model is tested with synthetic noisy BRDF data.
A regularised one-dimensional drop formation and coalescence model using a total variation diminishing (TVD) scheme on a single Eulerian grid

The breakup of an axisymmetric viscous jet is considered in the lubrication approximation. The discretised equations are solved on a fixed equidistant one-dimensional Eulerian grid. The governing equations are implemented in a conservative second order accurate total variation diminishing (TVD) scheme, preventing the numerical diffusivity. Singularities that occur at pinchoff and coalescence are regularised by a small modification on the surface tension. The modification is of the order of the spatial step Δx. This regularisation ensures that the solution of the presented numerical model converges to the exact solution of the breakup of a jet in the lubrication approximation. The results of the presented numerical model agree quantitatively with the analytical solution of the Rayleigh–Plateau instability, and with experimental results on the final stage of the Rayleigh–Plateau instability.
Constraining regional glacier reconstructions using past ice thickness of deglaciating areas – a case study in the European Alps

Abstract. In order to assess future glacier evolution and meltwater runoff, accurate knowledge on the volume and the ice thickness distribution of glaciers is crucial. However, in situ observations of glacier thickness are sparse in many regions worldwide due to the difficulty of undertaking field surveys. This lack of in situ measurements can be partially overcome by remote-sensing information. Multi-temporal and contemporaneous data on glacier extent and surface elevation provide past information on ice thickness for retreating glaciers in the newly deglacierized regions. However, these observations are concentrated near the glacier snouts, which is disadvantageous because it is known to introduce biases in ice thickness reconstruction approaches. Here, we show a strategy to overcome this generic limitation of so-called retreat thickness observations by applying an empirical relationship between the ice viscosity at locations with in situ observations and observations from digital elevation model (DEM) differencing at the glacier margins. Various datasets from the European Alps are combined to model the ice thickness distribution of Alpine glaciers for two time steps (1970 and 2003) based on the observed thickness in regions uncovered from ice during the study period. Our results show that the average ice thickness would be substantially underestimated (∼ 40 %) when relying solely on thickness observations from previously glacierized areas. Thus, a transferable topography-based viscosity scaling is developed to correct the modelled ice thickness distribution. It is shown that the presented approach is able to reproduce region-wide glacier volumes, although larger uncertainties remain at a local scale, and thus might represent a powerful tool for application in regions with sparse observations.
Advanced laminated antiferromagnetically coupled recording media with high thermal stability

A layered structure to improve the antiferromagnetic exchange coupling constant (J) in laminated antiferromagnetically coupled (LAC) media is proposed. This structure has a much larger thermal stability in comparison to simple LAC structures. It also improves the coercivity and decreases the remnant moment-thickness product to achieve a high resolution and a low pulse width. The recording measurements indicate that this structure has a slightly larger noise than the simple LAC structures. However, its overall signal-to-noise ratio (SNR) is comparable to that of the simple LAC structures. High SNR and much higher thermal stability make this structure suitable for ultrahigh areal densities.
On a functional equation arising in the analysis of a protocol for a multi-access broadcast channel

We analyse a stack protocol of the Capetanakis–Tsybakov–Mikhailov type for resolving collisions in a random multiple-access channel. We obtain a functional equation for the generating function of the expected collision resolution interval (CRI) durations, which is non-local with a non-commutative iteration semigroup. Using Mellin transform techniques and geometric properties of the iteration semigroup we show that for arrival rates smaller than a fixed threshold, the mean CRI duration for n initial colliders is asymptotically proportional to n. Ergodicity conditions are also demonstrated.
Hierarchical Planning and Reasoning about Partially Ordered Plans - From Theory to Practice

This invited paper (part of the New Faculty Highlights Invited Speaker Program of AAAI’21*) surveys my work done until today. The reviewed work focuses on hierarchical task network (HTN) planning as well as on partial order causal link (POCL) planning. Lines of research include theoretical investigations (mostly computational complexity analyses), heuristic search, as well as the practical application of the technology for planning-based assistants, which support a human user in carrying out various tasks.
A Framework for Estimating the Probability Distribution of Event Runoff Coefficient in Ungauged Catchments

The derived distribution method is a promising approach for flood estimation in ungauged catchments. In this approach, event runoff coefficient (ERC) is often adopted to behave as the runoff generation component since the behavior of ERC is closely related to flood generation mechanisms and its distribution reflects catchment climatological and landscape characteristics. However, there is a lack of understanding of how to transfer the information on ERC characteristics from gauged to ungauged catchments at catchment scale. Hence, here, we propose a generalized framework to estimate the probability distribution of ERC for ungauged catchments based on knowledge of the spatial and temporal controls on ERC from gauged catchments. Key components of the framework include cluster analysis based on ERC characteristics, linking clusters with catchment attributes, and constructing typical probability distribution of ERC conditioned on its temporal indicators. A total of 290,743 rainfall‐runoff events observed in 431 GB catchments during the period 1990–2014 have been employed to verify the framework. Good estimations are obtained with the median value of coefficient of determination (R2) reaching 0.85 across all test catchments. The results indicate that similar pre‐event catchment conditions may cause distinct runoff response in different catchments, thus predicting the correct spatial cluster is crucial to the estimation accuracy. This work sheds light on constructing a stochastic generator model of ERC according to its spatial pattern and temporal dynamic, facilitating a new alternative for flood estimation method in ungauged catchments.
Predisposing Factors in Dental and Oral Health Care During COVID-19

Background: Until this study was designed, there have been no studies related to internal risk factors from the patient's side in carrying out oral health care during the COVID-19 period, especially in Malang City. The purpose of this study was to determine the relationship between internal determinants of visitors to the Malang City Health Center in carrying out dental health care during the covid 19 period.Methods: The research design in this study was quantitative observational with a cross sectional approach. In this study cluster, random sampling was conducted in 4 sub-districts in Malang. The number of samples is 343 respondents. The instrument used was a questionnaire with the variables measured were attitudes, motivations, knowledge, perceptions and actions to take care of. The analysis used was univariate using percentages, bivariate using chi-square test and multivariate using logistic regression.Result: The results of the analysis obtained that the influence on the act of performing treatment can be explained by 23.5 percent by perceptions, motivations, knowledge, and attitudes, while the rest of the other influences are explained by other factors.Conclusion: The motivation and attitude variables of the respondents showed a significant influence. Meanwhile, the respondent's perception and knowledge variable did not show any significant effect.
Challenging behaviour and its risk factors in children and young people in a special school setting: A four wave longitudinal study.

BACKGROUND Longitudinal research is needed to strengthen evidence for risk factors for challenging behaviour in children with intellectual disabilities and to understand patterns of change over time. METHODS Data on challenging behaviour were collected for 225 students in one school over four annual time points and a range of potential risk correlates. Data were analysed using Generalised Estimating Equations. RESULTS Prevalence of challenging behaviour, aggression and self-injury did not vary significantly over time. Stereotyped behaviours increased over the 4-year period. Challenging behaviour was associated with lower levels of adaptive skills and autism. Stereotyped behaviour increased with age. Self-injurious behaviour was less likely to be shown in children with profound intellectual disabilities over time. CONCLUSIONS These findings are consistent with previous research in terms of potential risk factors identified. Implications for schools include proactive interventions for children with intellectual disabilities at high risk; especially those with autism and poorer adaptive skills.
Comparing the Effects of Tourists’ Perceptions of Residents’ Emotional Solidarity and Tourists’ Emotional Solidarity on Trip Satisfaction and Word-of-Mouth Intentions

This study aims to examine the effect of tourists’ perceptions of residents’ emotional solidarity with tourists on their trip satisfaction and word-of-mouth intentions toward a destination, taking into consideration the moderating effect of visitation frequency. It also aims to compare the impacts of tourists’ perceptions of residents’ emotional solidarity and the impacts of tourists’ perceptions of their emotional solidarity with residents. The results indicate that residents’ welcoming nature and emotional closeness as perceived by tourists have significant effects on tourists’ satisfaction and word-of-mouth intentions, while perceived residents’ sympathetic understanding does not. Visitation frequency significantly moderates the effects of perceptions of residents’ welcoming nature and emotional closeness on satisfaction. For tourists’ emotional solidarity, their sympathetic understanding has a significant effect on word-of-mouth intentions, and no moderating effect exists. This study has implications for exploring the differences in how tourists both receive from and offer to residents in terms of emotional solidarity.
Performance of a Shack-Hartmann wavefront sensor using real sodium laser data

The future of adaptive optics includes laser guide stars. While they are a great solution to sky coverage, they do introduce additional errors in the adaptive optics system. In particular, because of the finite thickness of the sodium layer, there is reduced centroiding accuracy due to elongated spots in the wavefront sensor. These become even more pronounced on large telescope apertures. In this paper we focus on the performance of a Shack-Hartmann wavefront sensor for 30m-plus large aperture telescopes studying the consequences of both the decrease in signal to noise ratio due to the spot elongation and the variations of the sodium density variations in the mesosphere. We incorporate real on-sky measurements of the return from the sodium layer using images of the laser guide star taken at Lick Observatory and simulate the expected wavefront reconstruction performance in the case of a Thirty Meter Telescope. Using this ensemble of data, we compare performance for various Hartmann centroiding methods, including correlation and weighted least square algorithms.
Coronary Slow Flow Is Not Diagnostic of Microvascular Dysfunction in Patients With Angina and Unobstructed Coronary Arteries

Background Guidelines recommend that coronary slow flow phenomenon (CSFP), defined as corrected thrombolysis in myocardial infarction frame count (CTFC) >27, can diagnose coronary microvascular dysfunction (CMD) in patients with angina and nonobstructed coronary arteries. CSFP has also historically been regarded as a sign of coronary endothelial dysfunction (CED). We sought to validate the utility of CTFC, as a binary classifier of CSFP and as a continuous variable, to diagnose CMD and CED. Methods and Results Patients with angina and nonobstructed coronary arteries had simultaneous coronary pressure and flow velocity measured using a dual sensor‐tipped guidewire during rest, adenosine‐mediated hyperemia, and intracoronary acetylcholine infusion. CMD was defined as the inability to augment coronary blood flow in response to adenosine (coronary flow reserve <2.5) and CED in response to acetylcholine (acetylcholine flow reserve ≤1.5); 152 patients underwent assessment using adenosine, of whom 82 underwent further acetylcholine testing. Forty‐six patients (30%) had CSFP, associated with lower flow velocity and higher microvascular resistance as compared with controls (16.5±6.9 versus 20.2±6.9 cm/s; P=0.001 and 6.26±1.83 versus 5.36±1.83 mm Hg/cm/s; P=0.009, respectively). However, as a diagnostic test, CSFP had poor sensitivity and specificity for both CMD (26.7% and 65.2%) and CED (21.1% and 56.0%). Furthermore, on receiver operating characteristics analyses, CTFC could not predict CMD or CED (area under the curve, 0.41 [95% CI, 0.32%–0.50%] and 0.36 [95% CI, 0.23%–0.49%], respectively). Conclusions In patients with angina and nonobstructed coronary arteries, CSFP and CTFC are not diagnostic of CMD or CED. Guidelines supporting the use of CTFC in the diagnosis of CMD should be revisited.
Spectroscopic Evidence for Excitonic Localization in Fractal Antenna Supermolecules

Direct experimental evidence is presented for the existence of localized excitations on fractal supermolecular structures that may serve as photonic antenna systems. For one dendrimer family the electronic spectra show no redshift with system size, indicating that the excitations are localized at the nodes of the Cayley trees describing these ordered structures. In contrast, similar dendrimers with varying lengths of the molecular branches exhibit a decrease in the band edge energy with a growing size of the system, consistent with a hierarchy of localization lengths. The latter corresponds to an energy funnel property of these ordered nanostructures. [S0031-9007(97)02375-2] PACS numbers: 33.20. Kf A new class of macromolecules known as dendrimers, which are synthesized by repeating units in a hierarchical self-similar fashion [1], has opened possibilities for designing and controlling chemical processes based on the Cayley tree topology of these objects. Dendrimers are characterized by the number of generations they are made of, by the basic building element, and by the branching of the end groups. The total number of the basic elements grows exponentially with the number of generations and the number of periphery elements is of the order of the bulk elements. Dendrimers are the only synthetic realizations of the, up to now, theoretical Cayley trees [2,3]. Their unique structure is expected to provide
Stability of the Rankine vortex in a multipolar strain field

In this paper, the linear stability of a Rankine vortex in an n-fold multipolar strain field is addressed. The flow geometry is characterized by two parameters: the degree of azimuthal symmetry n which is an integer and the strain strength e which is assumed to be small. For n=2, 3 and 4 (dipolar, tripolar and quadrupolar strain fields, respectively), it is shown that the flow is subject to a three-dimensional instability which can be described by the resonance mechanism of Moore and Saffman [Proc. R. Soc. London, Ser. A 346, 413 (1975)]. In each case, two normal modes (Kelvin modes), with the azimuthal wave numbers separated by n, resonate and interact with the multipolar strain field when their axial wave numbers and frequencies are identical. The inviscid growth rate of each resonant Kelvin mode combination is computed and compared to the asymptotic values obtained in the large wave numbers limits. The instability is also interpreted as a vorticity stretching mechanism. It is shown that the inviscid gr.
An Empirical Investigation of the Different Levels of Gamification in an Introductory Programming Course

Adding gaming elements to conventional teaching methodologies has gained a lot of attention because of its ability to incorporate an engaging, motivating, and fun-based environment. As a result, learners' dedication and performance are also better. Unfortunately, current gamification models do not consider the effect of different levels of gamification. Therefore, this study provides deeper insight into the three levels of gamification on the motivation, engagement, and performance of 450 undergraduates enrolled in an online course. The level of gamification is experimentally manipulated based on different gaming elements and the presentation of learning content. The outcomes were measured at three points. Quantitative methods were used to analyze defined measures, and qualitative methods were used to analyze open-ended measures. The results revealed no change in outcomes between all groups during pre-course and mid-course assessments. However, motivation, engagement, and performance are improved in gamified environments, and these effects are more noticeable towards the end of the course. It was discovered that the gamification level was a significant determinant of motivation and performance but not engagement, which highlights the importance of implementing gamification in educational platforms. The gamification appeared to be a pedagogically profound way of engaging students in the online course. The whole setup triggered the learner’s motivation to learn and perform in the course. We conclude that gamification does help in motivation, engagement and performance if considered properly. Thus, educators and educational institutions seeking to enhance student motivation and performance may look at the ‘right level’ of gamification as an appropriate methodology.