Miracle-dz/UniFAR-FTUs huggingface dataset:
Pedagogical models, collaborative work and interaction on online undergraduate programmes in Colombia: still some way to go

This article presents the results of a study whose aim was to explore the experiences and perceptions that students, lecturers/tutors and coordinators had of the pedagogical models underpinning online undergraduate programmes in Colombia, and of the application of these models with regard to collaborative work and interaction. The study used qualitative and quantitative techniques to complement and contrast the participants’ perceptions. A total of 48 group and individual interviews were conducted, and 288 students and 44 lecturers answered an online survey. The results show that the programmes are based on constructivist principles and tend to use active pedagogies pertaining to that theory. However, the lecturers and students expressed uncertainty about the implementation of collaborative work and the fostering of interaction.ResumenEl presente artículo expone los resultados de una investigación cuyo propósito fue explorar las percepciones y experiencias de estudiantes, docentes/tutores y coordinadores sobre los modelos pedagógicos que sirven de sustento para los programas de pregrado en modalidad virtual en Colombia y sobre la aplicación de esos modelos en relación con el trabajo colaborativo y la interacción. El estudio empleó técnicas cualitativas y cuantitativas para complementar y contrastar las percepciones de los participantes. Se realizaron 48 entrevistas grupales e individuales y una encuesta en línea a la que respondieron 288 estudiantes y 44 profesores. Los resultados revelan que los programas se fundamentan en los principios del constructivismo y tienden a utilizar pedagogías activas propias de esa corriente. Sin embargo, docentes y estudiantes manifiestan incertidumbres sobre la puesta en marcha del trabajo colaborativo y el fomento de la interacción.
THE CERTIFICATION ROLE OF PRIVATE EQUITY INVESTORS: EVIDENCE FROM INITIAL PUBLIC OFFERINGS ON THE NOUVEAU MARCHÉ AND THE NEUER MARKT

This paper presents an empirical analysis of whether independent and dependent private equity investors affect the underpricing of firms which went public on the Nouveau Marche and on the Neuer Markt between 1997 and 2000. In the sample of the Neuer Markt, the involvement of private equity investors reduces the underpricing of the firms’ shares only if private equity investors sell a part of their pre-flotation shares at the initial public offering (IPO). By contrast, in the sample of Nouveau Marche, private equity investors have no significant impact on the underpricing. Moreover, this paper presents an empirical analysis of whether dependent and independent private equity investors behave differently when the firms that they have financed go public. While the two groups of private equity investors do not differ with respect to their effect on underpricing, they do differ with respect to changes in their number of shares and thus with respect to their divestment behaviour. Independent private equity investors sell significantly more shares when their firms go public than their dependent counterparts do.
Determination Of Wear Coefficient Of Deformed And Heat Treated Copper

Since ages, copper and its alloys have found extensive applications in manufacture of bushes and bearings, heat transfer conductors, high conductivity electrical contactors and so on. However, currently, in all these applications, there is a significant enhancement in the service loads, wear resistance, conductivity thus forcing the material researchers to develop a newer class of copper based advanced materials. In this direction, researchers have focused their attention on improving the strength and the tribological properties copper. This paper describes the results of dry sliding wear tests of copper subjected to different deformations and with different heat treatments, under constant applied pressures of 0.2 MPa and at constant sliding speed of 3.35 m/s and for a total sliding distance of 2000 meters. The wear behavior was studied using a pin-on-disc apparatus against heat-treated steel counter surface, giving emphasis on the parameter wear coefficient as a function of different deformations (20%-60%) and different heat treatments (below Rx, Rx & above Rx). Wear coefficient of the deformed copper at room temperature for both central normal plane and central rolling plane was noted to be significantly higher initially and then decreased with increase in degree of deformation but increases with increase in heat treatment temperature. Further, it is understood that, the wear coefficient values of central normal plane are slightly higher than that of central rolling plane, attributing that the central rolling plane has stronger wear resistance than central normal plane. It is also observed that the wear coefficient varies between 10 -5 to 10 -4 , signifying the entire wear process as mild wear, from which it can be concluded that the experimental values are in good agreement with the theoretically calculated value.
Strategies for online inference of model-based clustering in large and growing networks

In this paper we adapt online estimation strategies to perform model-based clustering on large networks. Our work focuses on two algorithms, the first based on the SAEM algorithm, and the second on variational methods. These two strategies are compared with existing approaches on simulated and real data. We use the method to decipher the connexion structure of the political websphere during the US political campaign in 2008. We show that our online EM-based algorithms offer a good trade-off between precision and speed, when estimating parameters for mixture distributions in the context of random graphs.
Alkali-activated based concrete

Abstract: Portland cement-based products (primarily concretes) are the world’s most commonly used building materials. Due to its huge production worldwide, the Portland cement industry poses economic, energy and environmental problems (7% of total world-wide co 2 emissions). International concern over how to reduce co 2 emissions has given rise within the scientific community to a growing interest in the development of materials and technologies able to reduce the impact of Portland cement and make construction a more sustainable industry. One of the possible alternative materials whose study and use has intensified in recent years is so-called alkaline cement , produced by alkali-activating aluminosilicates, whether of natural or industrial (blast furnace slag, fly ash, etc.) origin. Based on the nature of their cementitious components (the CaO–SiO 2 –Al 2 O 3 system), alkaline cements may be grouped under two main categories: high-calcium and low-calcium cements. The reaction products governing the characteristics of the two types of end product differ. While the main reaction product precipitating in calcium-rich systems is a C-A-S-H type gel, in low calcium systems the reaction product is a N-A-S-H gel. A third type of alkaline cement, blended or hybrid cements, is a combination of the above. In this group, the reaction products comprise complex mixes of C-A-S-H + N-A-S-H gels. This chapter stresses the interest that has arisen around the study of these new cementitious systems.
GPU-efficient recursive filtering and summed-area tables

Image processing operations like blurring, inverse convolution, and summed-area tables are often computed efficiently as a sequence of 1D recursive filters. While much research has explored parallel recursive filtering, prior techniques do not optimize across the entire filter sequence. Typically, a separate filter (or often a causal-anticausal filter pair) is required in each dimension. Computing these filter passes independently results in significant traffic to global memory, creating a bottleneck in GPU systems. We present a new algorithmic framework for parallel evaluation. It partitions the image into 2D blocks, with a small band of additional data buffered along each block perimeter. We show that these perimeter bands are sufficient to accumulate the effects of the successive filters. A remarkable result is that the image data is read only twice and written just once, independent of image size, and thus total memory bandwidth is reduced even compared to the traditional serial algorithm. We demonstrate significant speedups in GPU computation.
Effects of wind and clothing apertures on local clothing ventilation rates and thermal insulation

The purpose of this study was to investigate the effects of wind (0, 1.1 m/s) and clothing apertures (not closed, closed hem, closed hem and neck) and the combined effects of them on local clothing ventilation rates and localized thermal insulation. Nine working jackets with identical design but different garment sizes and fabric permeability were made. The results showed that wind and clothing apertures had distinct effects both on the local ventilation rates and the local thermal insulation. The local ventilation rates of the right arm were largest at 1.1 m/s wind speed with the clothing hem closed. Chest and back ventilation rates were higher at wind than at no wind. Closing the garment hem affected the local thermal insulation of the impermeable garments mostly. In addition to wind and garment apertures, garment sizes and fabric permeability also impacted the local ventilation rates and the thermal insulation.
Characterization and simulation for 2.5-D interposer

Characterization of interposer in a 2.5-D stacked IC is essential for yield learning and design optimization. To examine the effect of design parameters of the interposer structure on different substrate materials, the S11 and S21 curves for various substrate materials are obtained from the full-wave simulation. With the simulation results, it is observed that polyimide and glass interposer shows better electrical performance compared to silicon interposer.
Myeloid Sarcoma in an Eyelid That Developed during Chemotherapy for Acute Myeloid Leukemia

An 80-year-old female presented with a mass in the left upper eyelid margin that had developed during chemotherapy for acute myeloid leukemia. The mass was elastic, hard, and pinkish, with a relatively smooth surface but without madarosis. The histopathological findings corresponded to a myeloid sarcoma. No blast cells were shown in the peripheral blood at the time of biopsy, and she subsequently underwent an azacitidine injection regimen. The size of the eyelid tumor decreased 3 months after the biopsy, when the course of azacitidine injections was completed. However, acute myeloid leukemia recurred, and the patient died 5 months after her first examination.
Teacher Education from E-Learner to E-Teacher: Master Curriculum.

E-learning and e-teaching systems are involved in teachers’ professional activities and development in several ways: (a) If e-learning/e-teaching is the technology which supports the process of teachers’ learning of university courses, the teacher is in the position of e-learner; (b) If e-learning/e-teaching is the content of the teachers’ university curricula in order to be applied in the teaching process, the teacher switches from the position of elearner to the one of e-teacher in blended or total e-learning systems. Systematic formal teacher education concerning e-learning/e-teaching implementation, and the structure of teachers’ ICT competencies and e-competencies, as well as the reasonss for their occurance, are considered in the paper. The Master curriculum of e-learning and an example of the programme realization are presented. The university curriculum of e-learning at Kragujevac University - Technical Faculty in Cacak (Serbia) was developed as a part of the international project (TEMPUS JEP-41016-2006). The curriculum focuses on the development of different e-roles for teachers and e-teachers: e-creator, e-designer, e-facilitator, e-tutor, e-moderator, etc. This master programme is a part of teacher in-service formal education for primary and secondary school teachers. In addition, the curriculum is adaptable to teachers’ pre-service education. However, it is more effective as a part of in-service education than as a part of pre-service undergraduate education, because the active teachers recognize their professional roles better than prospective teachers.
Welding and joining of magnesium alloys

Part 1 General: Introduction to the welding and joining of magnesium Welding metallurgy of magnesium alloys Preparation for welding of magnesium alloys Welding materials for magnesium alloys Welding and joining of magnesium alloys to aluminium alloys The joining of magnesium alloys to steel Corrosion and protection of magnesium alloy welds. Part 2 Particular welding and joining techniques: Brazing and soldering of magnesium alloys Mechanical joining of magnesium alloys Adhesive bonding of magnesium alloys Gas-tungsten arc welding (GTAW) of magnesium alloys Metal inert gas welding (MIG) of magnesium alloys Variable polarity plasma arc welding of magnesium alloys Hybrid laser-arc welding of magnesium alloys Activating flux tungsten inert gas (A-TIG) of magnesium alloys Friction stir welding of magnesium alloys Laser welding of magnesium alloys Resistance spot welding of magnesium alloys Electro-magnetic welding of Mg alloys.
Stem cell fate dictated solely by altered nanotube dimension

Two important goals in stem cell research are to control the cell proliferation without differentiation and to direct the differentiation into a specific cell lineage when desired. Here, we demonstrate such paths by controlling only the nanotopography of culture substrates. Altering the dimensions of nanotubular-shaped titanium oxide surface structures independently allowed either augmented human mesenchymal stem cell (hMSC) adhesion or a specific differentiation of hMSCs into osteoblasts by using only the geometric cues, absent of osteogenic inducing media. hMSC behavior in response to defined nanotube sizes revealed a very dramatic change in hMSC behavior in a relatively narrow range of nanotube dimensions. Small (≈30-nm diameter) nanotubes promoted adhesion without noticeable differentiation, whereas larger (≈70- to 100-nm diameter) nanotubes elicited a dramatic stem cell elongation (≈10-fold increased), which induced cytoskeletal stress and selective differentiation into osteoblast-like cells, offering a promising nanotechnology-based route for uniqueorthopedics-related hMSC treatments.
Fairness Provision in the IEEE 802.11e Infrastructure Basic Service Set

Most of the deployed IEEE 802.11e Wireless Local Area Networks (WLANs) use infrastructure Basic Service Set (BSS) in which an Access Point (AP) serves as a gateway between wired and wireless domains. We present the unfairness problem between the uplink and the downlink flows of any Access Category (AC) in the 802.11e Enhanced Distributed Channel Access (EDCA) when the default settings of the EDCA parameters are used. We propose a simple analytical model to calculate the EDCA parameter settings that achieve weighted fair resource allocation for all uplink and downlink flows. We also propose a simple model-assisted measurement-based dynamic EDCA parameter adaptation algorithm. Moreover, our dynamic solution addresses the differences in the transport layer and the Medium Access Control (MAC) layer interactions of User Datagram Protocol (UDP) and Transmission Control Protocol (TCP). We show that proposed Contention Window (CW) and Transmit Opportunity (TXOP) limit adaptation at the AP provides fair UDP and TCP access between uplink and downlink flows of the same AC while preserving prioritization among ACs.
Effects of retinal position on the visuo-motor adaptation of visual stability in a virtual environment

Although the retinal image changes a great deal with the movement of our head or eyes, we perceive a stable world (a phenomenon known as visual stability or position constancy). Visual stability adaptively changes for each new combination of vision and head motion, or to compensate for manipulated visuo-motor gain. This study aims to investigate the effects of retinal positions on visuo-motor adaptation and to discuss the neural mechanisms involved. I found that visuo-motor adaptation occurred, and was transferable from right to left visual fields (Experiment 1), between the upper and lower visual fields (Experiment 2), and between the central and peripheral visual fields (Experiment 4), and that for the left visual field (Experiment 1) and the large visual field (Experiment 3) visuo-motor adaptations were effective. The dominance of the central vision was found in Experiment 3 but not found in Experiment 4. These results suggest that the visuo-motor adaptation of visual stability was not specific to the retinal location, but is processed by a relatively high level of the perceptual system.
Comparison of properties of mould powders with identical chemical composition produced from different raw materials

An investigation was carried out to clarify the effect of the chemical composition of mould powder on its properties. A suitable commercial mould powder used for casting of some alloy steels was analysed. Ten different powders were designed to have identical elemental chemical composition but with some different phases using different raw material sources. These 11 powders were fired to 1300°C for 1 h. X-ray diffraction (XRD) analysis indicated that main phases are essentially the same. Prediction of mould flux viscosity by viscosity models yields identical values for all specimens. Melting rate was calculated for all samples and resulted similar values. With the same particle size range, bulk density of all powders was almost the same. The properties of the samples were similar and all with very good lubrication behaviour. It was concluded that the role of elemental chemical analysis in mould powders is more important than phase analysis and the raw materials used. This offers the opportunity for using 'waste' products as sources of raw materials for mould powders.
Unknown Rewards in Finite-Horizon Domains

"Human computation" is a recent approach that extracts information from large numbers of Web users. reCAPTCHA is a human computation project that improves the process of digitizing books by getting humans to read words that are difficult for OCR algorithms to read (von Ahn et al., 2008). In this paper, we address an interesting strategic control problem inspired by the reCAPTCHA project: given a large set of words to transcribe within a time deadline, how can we choose the difficulty level such that we maximize the probability of successfully transcribing a document on time? Our approach is inspired by previous work on timed, zero-sum games, as we face an analogous timed policy decision on the choice of words to present to users. However, our Web-based word transcribing domain is particularly challenging as the reward of the actions is not known; i.e., there is no knowledge if the spelling provided by a human is actually correct. We contribute an approach to solve this problem by checking a small fraction of the answers at execution time, obtaining an estimate of the cumulative reward. We present experimental results showing how the number of samples and time between samples affects the probability of success. We also investigate the choice of aggressive or conservative actions with regard to the bounds produced by sampling. We successfully apply our algorithm to real data gathered by the reCAPTCHA project.
Testing of nine different xeno-free culture media for human embryonic stem cell cultures.

BACKGROUND Human embryonic stem cells (hESC) are excellent candidates for cell replacement therapies. However, currently used culture conditions contain animal-derived components that bear a risk of transmitting animal pathogens and incorporation of non-human immunogenic molecules to hESC. METHODS Nine xeno-free culture media were compared with the conventional serum replacement (ko-SR) containing media in the culture of hESC on human feeder cells. Cultured hESC were characterized immunocytochemically and by fluorescence-activated cell sorter analysis. The differentiation potential of hESC cultured with xeno-free media was determined with the RT-PCR analysis. RESULTS The hESC cultured in xeno-free media differentiated or the proliferation decreased substantially. Under some test conditions, the morphology of the feeder cells was altered considerably. The hESC cultured with human serum underwent excessive differentiation in the beginning of culture, but a fraction of hESC was able to adapt to culture conditions containing 20% of human serum. CONCLUSIONS None of the studied xeno-free media was able to maintain the undifferentiated growth of hESC. The medium containing 20% human serum was found to sustain undifferentiated hESC proliferation to some extent, yet was inferior to the conventional ko-SR-containing medium.
Enhanced antitumor efficacy by blocking activation of the phosphatidylinositol 3‐kinase/Akt pathway during anti‐angiogenesis therapy

Anti‐angiogenesis has been a promising strategy for cancer therapy. However, many signal pathways are activated during anti‐angiogenic treatment to counteract the therapeutic efficacy. Among these pathways, evidence has directly pointed to the phosphatidylinositol 3‐kinase/Akt (PI3K/Akt) pathway, whose activation resulted in tolerance to the absence of nutrients and oxygen when tumor angiogenesis has been inhibited. In the present study, we investigated the effects of blocking activation of the PI3K/Akt pathway on cell survival in vitro and tumor growth in vivo during anti‐angiogenesis therapy. In modeled microenvironments in vitro, we observed that the phosphorylation of Akt in tumor cells was increased gradually in the absence of serum and oxygen in a time‐dependent manner. The specific inhibitors of PI3K inhibited the proliferation of tumor cells in a dose‐dependent manner in vitro. Moreover, inhibition was enhanced gradually with increased serum deprivation and/or hypoxia. In a mouse tumor model, we found the phosphorylation of Akt obviously increased following anti‐angiogenic therapy using plasmids encoding soluble vascular endothelial growth factor receptor‐2, but significantly reduced after treatment with LY294002. Consequently, the combinational treatment exhibited better antitumor effects compared with single treatments, presenting larger necrosis‐like areas, more apoptotic cells, less microvessel density and less phosphorylated Akt in tumors. These results suggest that blocking activation of the PI3K/Akt pathway during anti‐angiogenesis therapy could enhance antitumor efficacy. Thus, targeting the PI3K/Akt pathway might be a promising strategy to reverse tumor resistance to anti‐angiogenesis therapy. (Cancer Sci 2011; 102: 1469–1475)