Miracle-dz/UniFAR-FTUs huggingface dataset:
A Projection-Based Variational Multiscale Method for Large-Eddy Simulation with Application to Non-Isothermal Free Convection Problems

We consider a projection-based variational multiscale method for large-eddy simulation of the Navier–Stokes/Fourier model of incompressible, non-isothermal flows. For the semidiscrete problem, an a priori error estimate is given for rather general nonlinear, piecewise constant coefficients of the subgrid models for the unresolved scales of velocity, pressure, and temperature. Then we address aspects of the discretization in time. Finally, the design of the subgrid scale models is specified for the case of free convection problems and studied for the standard benchmark problem of free convection in a closed cavity.
A grid of MARCS model atmospheres for late-type stars.: II. S stars and their properties

S-type stars are late-type giants whose atmospheres are enriched in carbon and s-process elements because of either extrinsic pollution by a binary companion or intrinsic nucleosynthesis and dredge-up on the thermally-pulsing asymptotic giant branch. A grid of MARCS model atmospheres has been computed for S stars, covering the range 2700 ≤ T eff (K) ≤ 4000, 0.50 ≤ C/O ≤ 0.99, 0 ≤ log g ≤ 5, [Fe/H] = 0. , −0.5 dex, and [s/Fe] = 0, 1, and 2 dex (where the latter quantity refers to the global overabundance of s-process elements). The MARCS models make use of a new ZrO line list. Synthetic spectra computed from these models are used to derive photometric indices in the Johnson and Geneva systems, as well as TiO and ZrO band strengths. A method is proposed to select the model best matching any given S star, a non-trivial operation since the grid contains more than 3500 models covering a five-dimensional parameter space. The method is based on the comparison between observed and synthetic photometric indices and spectral band strengths, and has been applied on a vast subsample of the Henize sample of S stars. Our results confirm the old claim by (, MNRAS, 190, 441) that ZrO bands in warm S stars (T eff >3200 K) are not caused by the C/O ratio being close to unity, as traditionally believed, but rather by some Zr overabundance. The TiO and ZrO band strengths, combined with V −K and J −K photometric indices, are used to select T eff , C/O, [Fe/H] and [s/Fe]. The Geneva U −B 1 and B 2 −V 1 indices (or any equivalent) are good at selecting the gravity. The defining spectral features of dwarf S stars are outlined, but none is found among the Henize S stars. More generally, it is found that, at T eff = 3200 K, a change of C/O from 0.5 to 0.99 has a strong impact on V −K (2 mag). Conversely, a range of 2 mag in V −K corresponds to a 200 K shift along the (T eff , V −K ) relationship (for a fixed C/O value). Hence, the use of a (T eff , V −K ) calibration established for M stars will yield large errors for S stars, so that a specific calibration must be used, as provided in the present paper. Using the atmospheric parameters derived by our method for the sample of Henize S stars, we show that the extrinsic-intrinsic dichotomy among S stars reveals itself very clearly as a bimodal distribution in the effective temperatures. Moreover, the increase of s-process element abundances with increasing C/O ratios and decreasing temperatures is apparent among intrinsic stars, confirming theoretical expectations.
An Italian Question Answering System for Structured Data based on Controlled Natural Languages

Question Answering over structured data represents one of the main challenges in the field of Natural Language Processing since it requires to render natural language, which is used by people every day, into a formal language, which can be processed by a machine. This task is particularly tricky due to the gap between the vocabularies adopted by users and the formalism that characterizes any query language. For this reason, although its birth as a discipline dates back to the late sixties, Question Answering over structured data is still accomplished to an unsatisfying degree. This result is even more critical if we take into account languages different from English, for which the amount of available resources is limited. In this paper we present MULIB, a Question Answering system capable of answering questions in Italian over both Knowledge Bases and databases.
UAV-Based FSO Communications for High Speed Train Backhauling

In line with the increasing number of high speed train (HST) commuters and their demand for mobile data, railways operators expore means of providing high speed onboard wireless access. The data from all train cars are sent to a gateway terminal mounted at the roof of the train and an efficient backhaul solution is required to connect the train to the nearest base station. In this paper, we propose the use of unmanned aerial vehicles (UAVs) equipped with free space optical (FSO) communication terminal to provide backhauling for HSTs. We present a composite fading model for UAV-to-HST channel where both atmospheric turbulence and pointing errors due to position/orientation deviation are considered. Based on the derived fading model, we present closed form expressions for the bit error and outage probability. We further investigate the effect of several parameters such as beam divergence angle, displacement deviation variance, coverage distance and UAV operation altitude on system performance.
Universal Adversarial Perturbations Against Person Re-Identification

Person re-identification (re-ID) has made great progress and achieved high performance in recent years with the development of deep learning. However, as an application related to security issues, there are few researches considering the safety of person re-ID systems. In this paper, we attempt to explore the robustness of current person re-ID models against adversarial samples. Specifically, we attack the re-ID models using universal adversarial perturbations (UAPs), which are especially dangerous to the surveillance systems because it could fool most pedestrian images with a little overhead. Existing methods for UAPs mainly consider classification models, while the tasks in open set scenarios like re-ID are rarely explored. Re-ID attack is different from classification ones in the sense that the former discards decision boundary during test and cares more about the ranking list. Therefore, we propose an effective method to train UAPs against person re-ID models from the global list-wise perspective. Furthermore, to increase the impact of attack to different models and datasets, we propose a novel UAPs learning method based on total variation minimization. Extensive experiments validate the effectiveness of our proposed method.
Recommendation-based Team Formation for On-demand Taxi-calling Platforms

On-demand taxi-calling platforms often ignore the social engagement of individual drivers. The lack of social incentives impairs the work enthusiasms of drivers and will affect the quality of service. In this paper, we propose to form teams among drivers to promote participation. A team consists of a leader and multiple members, which acts as the basis for various group-based incentives such as competition. We define the Recommendation-based Team Formation (RTF) problem to form as many teams as possible while accounting for the choices of drivers. The RTF problem is challenging. It needs both accurate recommendation and coordination among recommendations, since each driver can be in at most one team. To solve the RTF problem, we devise a Recommendation-Matrix-Based Framework (RMBF). It first estimates the acceptance probability of recommendations and then derives a recommendation matrix to maximize the number of formed teams from a global view. We conduct trace-driven simulations using real data covering over 64,000 drivers and deploy our solution on a large on-demand taxi-calling platform for online evaluations. Experimental results show that RMBF outperforms the greedy-based strategy by forming up to 20% and 12.4% teams in trace-driven simulations and online evaluations, and the drivers who form teams and are involved in the competition have more service time, number of finished orders and income.
`Constraint consistency' at all orders in cosmological perturbation theory

We study the equivalence of two—order-by-order Einstein's equation and Reduced action—approaches to cosmological perturbation theory at all orders for different models of inflation. We point out a crucial consistency check which we refer to as `Constraint consistency' condition that needs to be satisfied in order for the two approaches to lead to identical single variable equation of motion. The method we propose here is quick and efficient to check the consistency for any model including modified gravity models. Our analysis points out an important feature which is crucial for inflationary model building i.e., all `constraint' inconsistent models have higher order Ostrogradsky's instabilities but the reverse is not true. In other words, one can have models with constraint Lapse function and Shift vector, though it may have Ostrogradsky's instabilities. We also obtain single variable equation for non-canonical scalar field in the limit of power-law inflation for the second-order perturbed variables.
Economies of Scale and Cost Efficiency in Small Scale Maize Production: Empirical Evidence from Nigeria

Abstract This paper presents empirical study of economies of scale and cost efficiency of small scale maize production in Ondo State of Nigeria, using farm level survey data collected from 200 farms in the study area. The results shows that there is a relative presence of economies of scale among the farmers meaning that an average farm in the sampled area produce at a minimum cost considering the size of the farm which is an indication that they operates in stage II of production surface (stage of efficient utilization of resource). This result was further collaborated by the mean cost efficiency of 1.161 obtained from the data analysis which shows that an average farm in the sample area is about 16% above the frontier cost, indicating that they are relatively efficient in allocating their scarce resources. The result of the analysis indicate that presence of cost inefficiency effects in the maize production as depicted by the significant estimated gamma coefficient of about 0.81 and the generalized likelihood ratio test result obtained from the data analysis.
Dissociation in Cerebral Scaling of Size Potgieser

Estimating size and distance is crucial in effective visuomotor control. The concept of an internal coordinate system implies that visual and motor size parameters are scaled onto a common template. To dissociate perceptual and motor components in such scaling, we performed an fMRI experiment in which 16 right-handed subjects copied geometric figures while the result of drawing remained out of sight. Either the size of the example figure varied while maintaining a constant size of drawing (visual incongruity) or the size of the examples remained constant while subjects were instructed to make changes in size (motor incongruity). These incongruent were compared to congruent conditions. Statistical Parametric Mapping (SPM8) revealed brain activations related to size incongruity in the dorsolateral prefrontal and inferior parietal cortex, pre-SMA / anterior cingulate and anterior insula, dominant in the right hemisphere. This pattern represented simultaneous use of a ‘resized’ virtual template and actual picture information requiring spatial working memory, early-stage attention shifting and inhibitory control. Activations were strongest in motor incongruity while right pre-dorsal premotor activation specifically occurred in this condition. Visual incongruity additionally relied on a ventral visual pathway. Left ventral premotor activation occurred in all variably sized drawing while constant visuomotor size, compared to congruent size variation, uniquely activated the lateral occipital cortex additional to superior parietal regions. These results highlight size as a fundamental parameter in both general hand movement and movement guided by objects perceived in the context of surrounding 3D space.
Joint Beamforming and Location Optimization for Cooperative Content-Aware UAVs

In this paper, we study the downlink transmission in a multi-UAV enabled wireless communication system where different types of contents are requested by ground users. Particularly, in the system, we consider a number of UAVs each equipped with a cache that is refreshed during off-peak hour to store some contents to be requested by ground users. To harness their full potential, a novel cooperative communication for the cache-enabled UAVs is presented, and we formulate an optimization problem that jointly decides the UAV placement as well as the transmit beamforming to maximize the number of users admitted to the system. Since the formulated problem is a mixed-integer non-convex program, which is generally known to be NP-hard, we resort to an appealing framework developed from the conventional difference-of-convex (DC) programming. Numerical results reveal the superiority of employing cooperative UAVs over non-cooperative ones and offer some insights into how the flexible deployment of cooperative UAVs benefits the system performance.
Anti-yeast potential of some Annonaceae species from Cameroonian biodiversity

An increased incidence of candidiasis and cryptococcosis has been recorded within the last two decades, mainly due to the increase in number of immunocompromised patients. Moreover, the emergence of resistant pathogenic yeast strains coupled with the shortcomings of the available antifungal drugs have emphasized the need of new drugs. Within this framework, this study aimed at investigating extracts from fourteen Annonaceae plants species in vitro against the major causative agents of mycoses, namely Candida albicans, Candida parapsilosis and Cryptococcus neoformans . Plant extracts and partitioned fractions were screened by broth dilution method. Minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) of extracts were determined by microdilution method and subculture. Also, the effect of combined active hexane fraction (UAst H) of Uvaria angolensis stem extract with the reference ketoconazole was studied. MIC values ranged from 0.625 mg/mL (for the leaf extract of Uvaria banmanni- UBl) to ≥10 mg/mL. Fraction UAst H showed the broadest spectrum activity with MIC value of 2.5 mg/mL against all the tested yeasts. Moreover, UAst H exhibited synergistic interaction on C. albicans , Cr. neoformans and C. parapsilosis when combined with ketoconazole. Overall, the results achieved in this study are promising and indicate that plants species from Annonaceae family are possible sources of potent and synergistic anti-yeast extracts. Keywords : Annonaceae, Extract, Antifungal, Combination, Synergism.
Studies on the connections between atmospheric sulphuric acid, new particle formation and cloud condensation nuclei

Atmospheric aerosol particles (small nm to μm sized particles floating in air) are an important part of the atmosphere and the climate system. Aerosols directly scatter sunlight and influence cloud formation, thereby causing a net cooling effect on the climate which counteracts global warming caused by greenhouse gases. Aerosols, particularly those from anthropogenic pollution, also deteriorate human health. Aerosols originate either from direct particle emissions or are formed in the atmosphere from gas-phase vapours through nucleation. Aerosols have both anthropogenic and natural sources. In the atmosphere, particle formation occurs frequently in continental areas all around the globe, and it is an important source of aerosol particles and cloud condensation nuclei. Sulphuric acid is one of the main compounds in atmospheric particle formation, and it participates both in nucleation and particle growth. This thesis studied the process of atmospheric particle formation and specifically its connection to gaseous sulphuric acid, based on analysis of field measurement data and modelling. New particle formation rates were observed to correlate with sulphuric acid concentration to the power between 1–2. This correlation was notably different than expected on the basis of nucleation theories. Based on the observed linear and squared correlation, new semi-empirical parameterisations for atmospheric nucleation rate were proposed: the activation and kinetic nucleation mechanism. Empirical nucleation coefficients were determined from atmosperic field data measured at two field stations in Hyytiala, Finland, and Heidelberg, Germany. The correlation of new particle formation with sulphuric acid and the factors affecting the correlation were further investigated by performing simulations with an aerosol dynamical model. Atmospheric relative humidity was observed to correlate negatively with sulphuric acid concentration and particle formation rate. It was proposed that cloudiness at high relative humidities could decrease the amount of UV-radiation reaching the ground, thereby decreasing the formation of sulphuric acid through a photochemical reaction pathway. This thesis also investigated the ability of aerosol particles in boreal forest to act as cloud condensation nuclei (CCN). New particle formation events were observed to produce significant amounts of potential CCN. The results of this thesis provided new insights on atmospheric particle formation and its connection to sulphuric acid. The developed nucleation rate parameterisations are useful for modelling of aerosol formation in regional and global climate models. The CCN parameters determined for boreal forest environment can be applied in climate modelling to predict boreal forest aerosols’ effects on climate.
Pre-service Teachers’ Teaching Competencies: The Experience of Practising Teaching in Secondary Schools and Teacher Colleges

The purpose of this study was to explore the competences of pre-service teachers from Tanzania’s University of Dar es Salaam during practice teaching in secondary schools and teacher education colleges. The following were the objectives of the study: first to examine the ways pre-service teachers prepared for classroom teaching, and second to assess the effectiveness of pre-service teachers in managing classroom teaching and learning activities. The study involved 30 pre-service teachers and 8 educational officers from secondary schools and teacher colleges. The instruments for data collection were a questionnaire, semi-structured interviews, portfolio reviews, and classroom observations. Results revealed the limited competencies among pre-service teachers in classroom teaching. The study recommended reforms of the pre-service teachers’ professional development program, the improvement of the educational policies, and the cooperation between educational managers from schools, colleges, and the Ministry of Education for quality education .
Quantum-Resistance Authentication and Data Transmission Scheme for NB-IoT in 3GPP 5G Networks

The Narrow Band Internet of Things (NB-IoT) system has become an important branch of the Internet of Everything and is an indispensable part in future fifth Generation (5G) network. However, there is currently no effective access authentication scheme for the NB-IoT system in the future 5G network. According to the current 3GPP standard, NB-IoT devices still use the traditional access authentication method to perform the mutual authentication with the network, which may bring a lot of signaling and communication overheads. This problem will be more prominent when sea of NB-IoT devices simultaneously are activated in the 5G network. In this paper, we propose a quantum-resistance access authentication and data distribution scheme for massive NB-IoT devices. This scheme can implement access authentication and data transmission for a group of NB-IoT devices at the same time based on the lattice-based homomorphic encryption technology. Our scheme can not only greatly reduce the network burden, but also can achieve the strong security including privacy protection and resisting quantum attacks. Performance analysis results show that our solution has the desired efficiency.
Patterns of Search Result Examination: Query to First Action

To determine key factors that affect a user's behavior with search results, we conducted a controlled eye-tracking study of users completing search tasks using both desktop and mobile devices. We focus our investigation on users' behavior from their query to the first action they take with the search engine results page (SERP): either a click on a search result or a reformulation of their query. We found that a user deciding to reformulate a query rather than click on a result is best understood as being caused by the user's examination pattern not including a relevant search result. If a user sees a relevant result, they are very likely to click it. Of note, users do not look at all search results and their examination may be influenced by other factors. The key factors we found to explain a user's examination pattern are: the rank of search results, the user type, and the query quality. While existing research has identified rank and user types as important factors affecting examination patterns, to our knowledge, query quality is a new discovery. We found that user queries can be understood as either of weak or strong quality. Weak queries are those that the user may believe are more likely to fail compared to a strong query, and as a result, we find that users modify their examination patterns to view fewer documents when they issue a weak query, i.e. they give up sooner.
Unique Dividends for Retail Shareholders: Evidence from Shareholder Perks

Previous studies indicate that retail investors are thought of as noise traders, price-takers, and free riders. However, many managers worldwide embrace the expense and treat their retail shareholders favorably. We examine why firms provide small individual stockholders with special treatment by using Japanese shareholder perks, which resemble dividends that are only for small individual shareholders. We find that firms with a low number of individual shareholders and high boardownership tend to initiate shareholder perks. The number of individual shareholders increases dramatically after perk initiation. The high attractiveness of perks for individual investors ispositively associated with the stock return on the initiation announcement day and negatively associated with the cost of capital after initiation. The ex-perk day return is significantly negative, and the trading volume around the ex-perk day is significantly positive. The number of individual shareholders is positively associated with the discount premium and the abnormal volume around the ex-day. These results imply that firms introduce perks to attract individuals and that a preference clientele effect clearly exists in dealings around the ex-day.
Degradato o riqualificazione ? L ’ attività economica in un quartiere centrale in via di diversificazione Sommario

The paper analyses the relations between economic performance, social diversification and overall systemic transformation in a socially deprived, but dynamic subarea of Warsaw – Praga Północ. ‘Old Praga’ is treated here as a specific laboratory of contemporary urban change. Actually, its pre-war tradition of multiculturalism and the transformation into ‘historic slums’ under socialism imprinted on its memory clash with a recent socio-economic diversification, that is generated by an early-stage gentrification, and also by the inflow of ethnic minorities.