Building and evaluating resources for sentiment analysis in the Greek language

Sentiment lexicons and word embeddings constitute well-established sources of information for sentiment analysis in online social media. Although their effectiveness has been demonstrated in state-of-the-art sentiment analysis and related tasks in the English language, such publicly available resources are much less developed and evaluated for the Greek language. In this paper, we tackle the problems arising when analyzing text in such an under-resourced language. We present and make publicly available a rich set of such resources, ranging from a manually annotated lexicon, to semi-supervised word embedding vectors and annotated datasets for different tasks. Our experiments using different algorithms and parameters on our resources show promising results over standard baselines; on average, we achieve a 24.9% relative improvement in F-score on the cross-domain sentiment analysis task when training the same algorithms with our resources, compared to training them on more traditional feature sources, such as n-grams. Importantly, while our resources were built with the primary focus on the cross-domain sentiment analysis task, they also show promising results in related tasks, such as emotion analysis and sarcasm detection.     

Highly Hydrophobic ZIF‐8/Carbon Nitride Foam with Hierarchical Porosity for Oil Capture and Chemical Fixation of CO2

The introduction of hierarchical porosity into metal‐organic frameworks (MOFs) has been of considerable interest in gas separation and heterogeneous catalysis due to the efficient mass transfer kinetics through meso/macropores. Here, a facile, scalable approach is reported for the preparation of carbon nitride (CN) foams as structural templates with micrometer‐sized pores and high nitrogen content of 25.6 wt% by the fast carbonization of low‐cost melamine foam. The nitrogen functionalities of CN foam facilitate chemical anchoring and growth of ZIF‐8 (zeolitic imidazolate frameworks) crystals, which leads to the development of hierarchical porosity. The growth of ZIF‐8 crystals also renders CN foam, which is hydrophilic in nature, highly hydrophobic exhibiting 135° of water contact angle due to the enhanced surface roughness, thus creating a natural shield for the MOF crystals against water. The introduction of ZIF‐8 crystals onto the CN foam enables selective absorption of oils up to 58 wt% from water/oil mixtures and also facilitates the highly efficient conversion of CO₂ to chloropropene carbonate in a quantitative yield with excellent product selectivity. Importantly, this present approach could be extended to the vast number of MOF structures, including the ones suffering from water instability, for the preparation of highly functional materials for various applications.     

Vapor sorption in thin supported polymer films studied by white light interferometry

In the present study, we apply a white light interferometric methodology to study sorption of moisture and methanol vapor in thin films of poly(2-hydroxyethyl methacrylate) [PHEMA] and poly(methyl methacrylate) [PMMA], supported on oxidized silicon wafers. The measured equilibrium thickness expansion of each film, exposed to different activities of the vapor penetrant, is used to determine the sorption isotherm of the system. Results for relatively thick films (100 nm < L_o < 600 nm) are compared with corresponding literature data for bulk, free-standing films, obtained by direct gravimetric methods. Furthermore, PMMA films of thicknesses lower than 100 nm were employed in order to study the effect of the dry film's thickness, and of substrate, on fractional swelling.     

The Longest Path Problem has a Polynomial Solution on Interval Graphs

The longest path problem is the problem of finding a path of maximum length in a graph. Polynomial solutions for this problem are known only for small classes of graphs, while it is NP-hard on general graphs, as it is a generalization of the Hamiltonian path problem. Motivated by the work of Uehara and Uno (Proc. of the 15th Annual International Symp. on Algorithms and Computation (ISAAC), LNCS, vol. 3341, pp. 871–883, 2004), where they left the longest path problem open for the class of interval graphs, in this paper we show that the problem can be solved in polynomial time on interval graphs. The proposed algorithm uses a dynamic programming approach and runs in O(n ⁴) time, where n is the number of vertices of the input graph.     

Characterization of the supercontinuum radiation generated by self-focusing of few-cycle 800 nm pulses in argon

Self-focusing of few-cycle pulses in atmospheric-pressure argon results in a supercontinuum which differs remarkably from the case of longer pulses: under single-filament conditions it extends to 200 nm and 250 nm with 6 fs and 10 fs pulses, respectively; the radiation, including the shortest wavelengths, is collimated and shows no conical emission. The short-wavelength part is intrinsically at least as short as the incoming fundamental pulse. These features make the few-cycle supercontinuum attractive as a source of widely tunable 10 fs pump pulses for spectroscopic applications. We present extensive experimental results including the dependence of the spectrum on pulse energy, duration and chirp, filament length, gas pressure and a comparison with nitrogen and air. We discuss them and other features including the role of the third harmonic and identify the conditions required to get a single highly stable filament. We also present a model, based on self-guiding, which predicts useful scaling rules.     

A virtual 3D mobile guide in the INTERMEDIA project

In this paper, we introduce a European research project, interactive media with personal networked devices (INTERMEDIA) in which we seek to progress beyond home and device-centric convergence toward truly user-centric convergence of multimedia. Our vision is to make the user the multimedia center: the user as the point at which multimedia services and the means for interacting with them converge. This paper proposes the main research goals in providing users with a personalized interface and content independent of physical networked devices, and space and time. As a case study, we describe an indoors, mobile mixed reality guide system: Chloe@University. With a see-through head-mounted display (HMD) connected to a small wearable computing device, Chloe@University provides users with an efficient way to guide someone in a building. A 3D virtual character in front of the user guides him/her to the required destination.     

Serverless streaming for emerging media: towards 5G network-driven cost optimization

Multimedia Tools and Applications - Immersive 3D media is an emerging type of media that captures, encodes and reconstructs the 3D appearance of people and objects, with applications in...     

Understanding the effect of silica nanoparticles and exfoliated graphite nanoplatelets on the crystallization behavior of isotactic polypropylene

This study explores how the presence of nanofillers with different structural and chemical characteristics, specifically silica nanoparticles and exfoliated graphite nanoplatelets (GNP), alters the crystallization behavior and polymorphism of a semicrystalline polymer, such as polypropylene (PP). The main focus of this research is to investigate how silica and GNP affect the nucleation and growth of PP crystals during isothermal crystallization. The nonisothermal crystallization behavior, including crystal structures, crystallization temperature, and rate, is also determined. PP composites with nanomaterial content up to 7 wt% were produced by melt mixing and injection molding. Both silica and graphite were found to be effective nucleating agents, significantly increasing the crystallization rate during isothermal crystallization, with greater changes observed in case of GNP composites. The effect of filler type and amount on the PP polymorphism and lamella thickness was studied by X‐ray diffraction and modulated differential scanning calorimetry. Both silica and graphite were found to be effective nucleating agents for the less common β‐phase of PP crystals even at low nanomaterial concentration. α‐?crystal perfection and the recrystallization of the β‐form in the α‐form and/or at the transcrystalline regime were found to be responsible for the recrystallization occurring upon melting in nanocomposites at high silica or medium GNP content. POLYM. ENG. SCI., 55:672–680, 2015. © 2014 Society of Plastics Engineers     

Physical and thermo-mechanical properties of whey protein isolate films containing antimicrobials, and their effect against spoilage flora of fresh beef

The effectiveness of antimicrobial films against beef's spoilage flora during storage at 5 °C and the impact of the antimicrobial agents on the mechanical and physical properties of the films were examined. Antimicrobial films were prepared by incorporating different levels of sodium lactate (NaL) and -polylysine (-PL) into sorbitol-plasticized whey protein isolate (WPI) films. The moisture uptake behavior and the water vapor permeability (WVP) were affected only by the addition of NaL at all concentrations used since an increased water uptake and permeability were observed with the addition of NaL into the protein matrix. An increase of the glass transition temperature (5–15 °C) of the sorbitol region, as determined by Dynamic Mechanical Thermal Analysis (DMTA), was caused by the addition of -PL into the WPI specimens. Instead, incorporation of NaL into the protein matrix did not alter its thermo-mechanical behavior. The addition of NaL at concentrations of 1.0% and 1.5% w/w in the film-forming solution resulted in a decline of maximum tensile strength (σ_max) and Young modulus (E). A decrease of E and σ_max, accompanied with an increase in elongation at break (%EB), was also observed with increasing -PL concentration, at moisture contents higher that 10% (w/w). The antimicrobial activity of the composite WPI films was tested on fresh beef cut portions. The maximum specific growth rate (μ_max) of total flora (total viable count, TVC) was significantly reduced with the use of antimicrobial films made from 0.75% w/w -PL in film-forming solutions (p < 0.05), while the growth of Lactic Acid Bacteria was completely inhibited. Significant inhibition of growth of the total flora and pseudomonads was also observed with the use of films made with protein solutions containing 2.0% w/w NaL. These results pointed to the effectiveness of the antimicrobial whey protein films to extend the shelf life of fresh beef.