Miracle-dz/UniFAR-FTUs huggingface dataset:
Workload characterization and optimization of TPC-H queries on Apache Spark

Besides being an in-memory-oriented computing framework, Spark runs on top of Java Virtual Machines (JVMs), so JVM parameters must be tuned to improve Spark application performance. Misconfigured parameters and settings degrade performance. For example, using Java heaps that are too large often causes a long garbage collection pause time, which accounts for over 10-20% of application execution time. Moreover, recent computing nodes have many cores with simultaneous multi-threading technology and the processors on the node are connected via NUMA, so it is difficult to exploit best performance without taking into account of these hardware features. Thus, optimization in a full stack is also important. Not only JVM parameters but also OS parameters, Spark configuration, and application code based on CPU characteristics need to be optimized to take full advantage of underlying computing resources. In this paper, we used the TPC-H benchmark as our optimization case study and gathered many perspective logs such as application, JVM (e.g. GC and JIT), system utilization, and hardware events from a performance monitoring unit. We discuss current problems and introduce several JVM and OS parameter optimization approaches for accelerating Spark performance. As a result, our optimization exhibits 30-40% increase in speed on average and is up to 5x faster than the naive configuration.
Empirical properties of inter-cancellation durations in the Chinese stock market

Order cancellation process plays a crucial role in the dynamics of price formation in order-driven stock markets and is important in the construction and validation of computational finance models. Based on the order flow data of 18 liquid stocks traded on the Shenzhen Stock Exchange in 2003, we investigate the empirical statistical properties of inter-cancellation durations in units of events defined as the waiting times between two consecutive cancellations. The inter-cancellation durations for both buy and sell orders of all the stocks favor a $q$-exponential distribution when the maximum likelihood estimation method is adopted; In contrast, both cancelled buy orders of 6 stocks and cancelled sell orders of 3 stocks prefer Weibull distribution when the nonlinear least-square estimation is used. Applying detrended fluctuation analysis (DFA), centered detrending moving average (CDMA) and multifractal detrended fluctuation analysis (MF-DFA) methods, we unveil that the inter-cancellation duration time series process long memory and multifractal nature for both buy and sell cancellations of all the stocks. Our findings show that order cancellation processes exhibit long-range correlated bursty behaviors and are thus not Poissonian.
A force control structure based on the concept of virtual plant

In force control applications where a robot end-effector is required to interact with the environment or the workpiece, the dynamic of the environment plays an important role. The environment dynamic may influence the performance of the controlled system, especially the performance in transient period. In order to avoid tuning the controller constantly with the changing environment, a robust control algorithm is proposed. A virtual stiffness is implemented in parallel with the actual environmental stiffness and forms a “virtual plant”. In this paper, different algorithms to control the virtual plant are proposed. Simulation results show an improved performance in reducing the influence of the changing environmental stiffness, as well as the ability of rejecting disturbance.
[En]gendering the norms of customary inheritance in Botswana and South Africa

ABSTRACT The article responds to the article by Weinberg in this issue. She traces the trajectory of court hearings concerning the contested inheritance of land in Botswana, which, after several prior judgements eventually resulted in a positive outcome for the woman litigants. I acknowledge the author's key argument, which concerns the impact of power relations on the construction of customary law and the reproduction of knowledge in the courts. Certain versions of “custom” were promoted and others stilled to the disadvantage of women. I argue that the normative patterns of landholding are indeed gendered, but do not result in a binary structure of men and women. “Gender” should be disaggregated to take into account a range of status criteria within and across the categories of male and female in order to understand the differential impact of social relations on the outcomes of property struggles. The normative lines of property transmission frequently follow a logic of “family property” that allows for qualifying women to rights of property. Family property has vastly different social and legal consequences to private, individualised property rights. The corollary is that it is misleading to speak of the processes of succession to rights of access to, and control of customary property in terms of one-to-one “inheritance” of land. The concept of “living law” inadequately reflects these social dynamics.
Breaking the Chains: On Declarative Data Analysis and Data Independence in the Big Data Era

Data management research, systems, and technologies have drastically improved the availability of data analysis capabilities, particularly for non-experts, due in part to low-entry barriers and reduced ownership costs (e.g., for data management infrastructures and applications). Major reasons for the widespread success of database systems and today's multi-billion dollar data management market include data independence, separating physical representation and storage from the actual information, and declarative languages, separating the program specification from its intended execution environment. In contrast, today's big data solutions do not offer data independence and declarative specification. As a result, big data technologies are mostly employed in newly-established companies with IT-savvy employees or in large well-established companies with big IT departments. We argue that current big data solutions will continue to fall short of widespread adoption, due to usability problems, despite the fact that in-situ data analytics technologies achieve a good degree of schema independence. In particular, we consider the lack of a declarative specification to be a major road-block, contributing to the scarcity in available data scientists available and limiting the application of big data to the IT-savvy industries. In particular, data scientists currently have to spend a lot of time on tuning their data analysis programs for specific data characteristics and a specific execution environment. We believe that the research community needs to bring the powerful concepts of declarative specification to current data analysis systems, in order to achieve the broad big data technology adoption and effectively deliver the promise that novel big data technologies offer.
CLIMATE RESILIENCE AND ECONOMIC GROWTH IN DEVELOPING COUNTRIES

Background note The OECD is developing guidance to support governments and development partners in integrating climate change adaptation into their development strategies. To inform the development of that guidance, the OECD is coordinating two country case studies (Ethiopia and Colombia) and an Expert Workshop on " Climate Resilience and Economic Growth in Developing Countries " that will be held in Paris on 24 April 2013. This paper is intended to support the discussion at the expert workshop, by summarising the current knowledge in this area and highlighting some of the key challenges and emerging issues to be discussed at the workshop.
ContinuStreaming: Achieving high playback continuity of Gossip-based Peer-to-Peer streaming

Gossip-based peer-to-peer (P2P) streaming has been proved to be an effective and resilient method to stream qualified media contents in dynamic and heterogeneous network environments. Because of the intrinsic randomness of gossiping, some data segments cannot be disseminated to every node in time, which seriously affects the media playback continuity. In this paper we describe the design of ContinuStreaming, a gossip-based P2P streaming system which can maintain high resilience and low overhead while bring a novel and critical property - full coverage of the data dissemination. With the help of DHT, data segments which are likely to be missed by the gossip-based data scheduling can be quickly fetched by the on-demand data retrieval so as to guarantee continuous playback. We discuss the results of both theoretical analysis and comprehensive simulations on various real-trace overlay topologies to demonstrate the effectiveness of our system. Simulation results show that ContinuStreaming outperforms the existing representative gossip-based P2P streaming systems by increasing the playback continuity very close to 1.0 with only 4% or less extra overhead.
Reconstruction and analysis of Twitter conversation graphs

User interactions over social networks has been an emergent theme over the last several years. In contrast to previous work we focus on characterizing user communications patterns around an initial post, or conversation root. Specifically, we focus on how other users respond to these roots and how the complete conversation initiated by this root evolves over time. For this purpose we focus our investigation on Twitter, the biggest micro-blogging social network. To the best of our knowledge this is the first such method that is able to reconstruct complete conversations around initial tweets. We propose a robust approach for reconstructing complete conversations and compare the resulting graph structures against those obtained from previous crawling strategies based on keyword searches. Our crawl provides a large scale dataset, ideal for computer scientists to run large scale experimental evaluations, however our dataset is made of a collection of small scale, highly controlled and complete conversation graphs ideal for a sociological investigation. We believe our work will provide the proper dataset to establish concrete collaborations with interdisciplinary expertise.
The Effect of Periodontitis on Expression of Interleukin-21: A Systematic Review

Purpose. Inflammation and tissue breakdown are led by an array of inflammatory destructive mediators associated with initiation and progression of inflammatory diseases like periodontitis. Current evidence shows that these inflammatory mediators have a definitive role in the pathogenesis of various systemic diseases with an inflammatory component. Interleukin-21 (IL-21) has been associated with systemic diseases like rheumatoid arthritis and Crohn's disease that follow a chronic inflammatory cascade. Similarly recent studies have associated Interleukin-21 levels with periodontitis. This systematic review was aimed to assess the levels of IL-21 in subjects with periodontitis. Methods. A complete literature search was done in PubMed, Medline, Science Direct, and Cochrane databases and Google Scholar based on the inclusion/exclusion criteria. Six relevant articles were procured. Full text was read individually by two reviewers and data extraction was done based on STROBE statement. Results. After data extraction five observational and one interventional study were obtained. All the studies showed an increased expression of IL-21 in periodontitis and the interventional study showed reduction in IL-21 levels after nonsurgical periodontal therapy (NSP). Conclusion. Interleukin-21 levels are higher in periodontitis than controls. With this limited evidence further longitudinal studies are required to consider this as a definitive inflammatory marker.
Retrieval of atmospheric liquid and ice characteristics using dual-wavelength radar observations

Dual-wavelength (K/sub /spl alpha//- and X-band) radar measurements have shown promise in estimating the amount of liquid water in a cloud. By taking advantage of the attenuation by liquid water of the K/sub /spl alpha//-band signal as compared to X-band, the range-differentiated difference in reflectivity can be used to estimate the spatial distribution of cloud liquid water. One limitation is that the method is based on the assumption that all particles in the radar beams act as Rayleigh scatterers, that is, their diameters are small compared to the radar wavelengths. In natural clouds in wintertime conditions, this often may not be the case. This paper presents simulations of the response of these two wavelengths to conditions measured in several geographic locations. The simulations are used to build simplified relations between radar reflectivity and total mass and size distribution functions of liquid droplets and ice particles. Using these relations, it may be possible to estimate the sizes of the droplets, as well as total mass contents and size distributions of ice particles that may also be present in the sampled volume. Results of radar-based retrieval methods applied to measurements in a winter stratiform cloud are discussed, and compared with a previous result. A technique is described for detecting regions of non-Rayleigh scattering and for subsequently estimating liquid water content (LWC). Additional examples of dual-wavelength measurements in regions containing cloud droplets, small ice particles, and larger snowflakes are discussed.
Modeling and Reproducibility of Suzaku HXD PIN/GSO Background

Suzaku Hard X-ray Detector (HXD) achieved the lowest background level than any other previously or currently operational missions sensitive in the energy range of 10–600 keV, by utilizing PIN photodiodes and GSO scintillators mounted in BGO active shields to reject particle background and Compton-scattered events as much as possible. Because it does not have an imaging capability nor rocking mode for the background monitor, the sensitivity is limited by the reproducibility of the non X-ray background (NXB) model. We modeled the HXD NXB, which varies with time as well as other satellites with a low-Earth orbit, by utilizing several parameters, including particle monitor counts and satellite orbital/attitude information. The model background is supplied as an event file in which the background events are generated by random numbers, and can be analyzed in the same way as the real data. The reproducibility of the NXB model depends on the event selection criteria (such as cut-off rigidity and energy band) and the integration time, and the 1 systematic error is estimated to be less than 3% (PIN 15–40 keV) and 1% (GSO 50–100 keV) for more than 10 ks exposure.
Critical formation of trapped surfaces in the collision of gravitational shock waves

We study the formation of marginally trapped surfaces in the head-on collision of two shock waves both in anti-de Sitter and Minkowski space-time in various dimensions as a function of the spread of the energy density in transverse space. For D = 4 and D = 5 it is shown that there exists a critical value of this spread above which no solution to the trapped surface equation is found. In four dimensions the trapped surface at criticality has a finite size, whereas in five the critical size vanishes. In both cases we find scaling relations characterized by critical exponents. Finally, when D > 5 there is always a solution to the trapped surface equation for any transverse spread.
A Study on the Optimization of Surfactants in the Main and Vice Slug in Weak Base ASP Flooding

In ASP (Alkali-Surfactant-Polymer) flooding processes, surfactants help to enhance oil recovery by lowering the interfacial tension between the oil and water. However, due to the high cost of surfactants and the stability of the emulsion that varies with surfactant concentration, it is necessary to optimize the surfactant concentration in ASP flooding. In this study, we combined numerical simulation and physical experimental research to solve this problem. In order to screen for the optimal surfactant concentration in the main and vice slugs, CMG (Computer Measurement Group) numerical simulation software was used to change the surfactant concentration in the injected compound system and the oil recovery factor and the recovery percent of reserves were compared. The physical experiments were also carried out with different surfactant concentrations and the results verified the simulation results. It shows that the recovery factor increases with the surfactant concentration. The optimal surfactant concentration in the main and vice slug are 0.3% and 0.15%, respectively. As for improving the recovery factor, it is more efficient to increase the mass fraction of the surfactant in the vice slug than in the main slug. It demonstrates that the amount of surfactant in the main slug plays a more important role in displacing oil from the formation.
Macaque Retina Contains an S-Cone OFF Midget Pathway

Psychophysical results suggest that the primate visual system is equally sensitive to both the onset and offset of short-wavelength light and that these responses are carried by separate pathways. However, physiological studies of cells in the retina and lateral geniculate nucleus find far fewer OFF-center than ON-center cells whose receptive-field centers are driven by short-wavelength-sensitive (S) cones. To determine whether S cones contact ON and OFF midget bipolar cells as well as (ON) “blue-cone bipolar” cells (Mariani, 1984), we examined 118 contiguous cone terminals and their bipolar cells in electron micrographs of serial sections from macaque foveal retina. Five widely spaced cone terminals do not contact ON midget bipolar cells. These five cone terminals contact the dendrites of “blue-cone bipolar” cells instead, showing that they are the terminals of S cones. These S-cone terminals are smaller and contain more synaptic ribbons than other terminals. Like neighboring cones, each S cone contacts its own OFF midget bipolar cell via triad-associated (flat) synaptic contacts. Moreover, each S-cone OFF midget bipolar cell has a synaptic terminal in the outer half of the inner plexiform layer, where it contacts an OFF midget ganglion cell.
Série Scientifique Scientific Series Forecasting Expected Shortfall with a Generalized Asymmetric Student-t Distribution Forecasting Expected Shortfall with a Generalized Asymmetric Student-t Distribution

CIRANO Le CIRANO est un organisme sans but lucratif constitué en vertu de la Loi des compagnies du Québec. Le financement de son infrastructure et de ses activités de recherche provient des cotisations de ses organisations-membres, d'une subvention d'infrastructure du Ministère du Développement économique et régional et de la Recherche, de même que des subventions et mandats obtenus par ses équipes de recherche. CIRANO is a private non-profit organization incorporated under the Québec Companies Act. Its infrastructure and research activities are funded through fees paid by member organizations, an infrastructure grant from the Ministère du Développement économique et régional et de la Recherche, and grants and research mandates obtained by its research teams. Le CIRANO collabore avec de nombreux centres et chaires de recherche universitaires dont on peut consulter la liste sur son site web. Les cahiers de la série scientifique (CS) visent à rendre accessibles des résultats de recherche effectuée au CIRANO afin de susciter échanges et commentaires. Ces cahiers sont écrits dans le style des publications scientifiques. Les idées et les opinions émises sont sous l'unique responsabilité des auteurs et ne représentent pas nécessairement les positions du CIRANO ou de ses partenaires. This paper presents research carried out at CIRANO and aims at encouraging discussion and comment. The observations and viewpoints expressed are the sole responsibility of the authors. They do not necessarily represent positions of CIRANO or its partners. Résumé / Abstract De façon générale, les rendements financiers sont caractérisés par des queues épaisses et une certaine asymétrie. Ainsi, les modèles à variance conditionnelle dotés de ces caractéristiques donnent de meilleurs résultats que les modèles plus limités. La différence dans les résultats obtenus peut être particulièrement importante lorsqu'il s'agit d'évaluer des quantités qui dépendent des caractéristiques des queues, y compris les mesures du risque, tel que le manque à gagner prévu. Dans le cas actuel, en recourant à une généralisation récente de la distribution asymétrique suivant la loi t de Student, de sorte que des paramètres distincts limitent l'asymétrie et l'épaisseur de chaque queue, nous intégrons les rendements financiers quotidiens et estimons le manque à gagner prévu dans le cas de l'indice S&P 500 et de certaines actions de compagnies individuelles. La distribution généralisée est utilisée pour les innovations normalisées contenues dans un modèle asymétrique non linéaire de type GARCH. Les résultats démontrent de façon empirique l'utilité de la distribution généralisée pour améliorer les prévisions au sujet …
Monocular road mosaicing for urban environments

Marking-based lane recognition requires an unobstructed view onto the road. In practice however, heavy traffic often constrains the visual field, especially in urban scenarios such as urban crossroads. In this paper we present a novel approach to road mosaicing for dynamic environments. Our method is based on a multistage registration procedure and uses blending techniques. We show that under modest assumptions accurate registration is possible from monocular image sequences. We further demonstrate that fusing visual information from previous frames into the current view can greatly extend the camera's field of view.
Preferred repairs for inconsistent databases

The objective of this paper is to investigate the problems related to the extensional integration of information sources. In particular, we propose an approach for managing inconsistent databases, i.e. databases violating integrity constraints. The presence of inconsistent data can be resolved by "repairing" the database, i.e. by providing a computational mechanism that ensures obtaining consistent "scenarios" of the information or by consistently answering to queries posed on an inconsistent set of data. In this paper we consider preferences among repairs and possible answers by introducing a partial order among them on the base of some preference criteria. More specifically, preferences are expressed by considering polynomial functions applied to repairs and returning real numbers. The goodness of a repair is measured by estimating how much it violates the desiderata conditions and a repair is preferred if it minimizes the value of the polynomial function used to express the preference criteria. The main contribution of this work consists in the proposal of a logic approach for querying and repairing inconsistent databases that extends previous works by allowing to express and manage preference criteria. The approach here proposed allows to express reliability on the information sources and is also suitable for expressing decision and optimization problems. The introduction of preference criteria strongly reduces the number of feasible repairs and answers; for special classes of constraints and functions it gives a unique repair and answer.