bluuebunny/crossref_metadata_2025 huggingface dataset:
Project 1640 Observations of Brown Dwarf GJ 758 B: Near-infrared Spectrum and Atmospheric Modeling
Authors: Nilsson R. , Veicht A. , Godfrey P. A. Giorla , Rice E. L. , Aguilar J. , Pueyo L. , Roberts L. C. , Oppenheimer R. , Brenner D. , Luszcz-Cook S. H. , Bacchus E. , Beichman C. , Burruss R. , Cady E. , Dekany R. , Fergus R. , Hillenbrand L. , Hinkley S. , King D. , Lockhart T. , Parry I. R. , Sivaramakrishnan A. , Soummer R. , Vasisht G. , Zhai C. , Zimmerman N. T.
Published: March 2017

The nearby Sun-like star GJ 758 hosts a cold substellar companion, GJ 758 B, at a projected separation of ≲30 au, previously detected in high-contrast multi-band photometric observations. In order to better constrain the companion’s physical characteristics, we acquired the first low-resolution (R ∼ 50) near-infrared spectrum of it using the high-contrast hyperspectral imaging instrument Project 1640 on Palomar Observatory’s 5 m Hale telescope. We obtained simultaneous images in 32 wavelength channels covering the Y, J, and H bands (∼952–1770 nm), and used data processing techniques based on principal component analysis to efficiently subtract chromatic background speckle-noise. GJ 758 B was detected in four epochs during 2013 and 2014. Basic astrometric measurements confirm its apparent northwest trajectory relative to the primary star, with no clear signs of orbital curvature. Spectra of SpeX/IRTF observed T dwarfs were compared to the combined spectrum of GJ 758 B, with χ
2 minimization suggesting a best fit for spectral type T7.0 ± 1.0, but with a shallow minimum over T5–T8. Fitting of synthetic spectra from the BT-Settl13 model atmospheres gives an effective temperature T
eff = 741 ± 25 K and surface gravity

dex (cgs). Our derived best-fit spectral type and effective temperature from modeling of the low-resolution spectrum suggest a slightly earlier and hotter companion than previous findings from photometric data, but do not rule out current results, and confirm GJ 758 B as one of the coolest sub-stellar companions to a Sun-like star to date.
The Shadow Knows: Using Shadows to Investigate the Structure of the Pretransitional Disk of HD 100453
Authors: Long Zachary C. , Fernandes Rachel B. , Sitko Michael , Wagner Kevin , Muto Takayuki , Hashimoto Jun , Follette Katherine , Grady Carol A. , Fukagawa Misato , Hasegawa Yasuhiro , Kluska Jacques , Kraus Stefan , Mayama Satoshi , McElwain Michael W. , Oh Daehyon , Tamura Motohide , Uyama Taichi , Wisniewski John P. , Yang Yi
Published: March 2017

We present Gemini Planet Imager polarized intensity imagery of HD 100453 in Y, J, and K1 bands that reveals an inner gap (9–18 au), an outer disk (18–39 au) with two prominent spiral arms, and two azimuthally localized dark features that are also present in Spectro-Polarimetric High-contrast Exoplanet REsearch (SPHERE) total intensity images. Spectral energy distribution fitting further suggests that the radial gap extends to 1 au. The narrow, wedge-like shape of the dark features appears similar to predictions of shadows cast by an inner disk that is misaligned with respect to the outer disk. Using the Monte Carlo radiative transfer code HOCHUNCK3D, we construct a model of the disk that allows us to determine its physical properties in more detail. From the angular separation of the features, we measure the difference in inclination between the disks (45°) and their major axes, PA = 140° east of north for the outer disk, and 100° for the inner disk. We find an outer-disk inclination of 25° ± 10° from face-on, in broad agreement with the Wagner et al. measurement of 34°. SPHERE data in J and H bands indicate a reddish disk, which indicates that HD 100453 is evolving into a young debris disk.
Convectively Driven Sinks and Magnetic Fields in the Quiet-Sun
Authors: Requerey Iker S. , Del Toro Iniesta Jose Carlos , Rubio Luis R. Bellot , Pillet Valentín Martínez , Solanki Sami K. , Schmidt Wolfgang
Published: March 2017

We study the relation between mesogranular flows, convectively driven sinks and magnetic fields using high spatial resolution spectropolarimetric data acquired with the Imaging Magnetograph eXperiment on board Sunrise. We obtain the horizontal velocity flow fields of two quiet-Sun regions (31.2 × 31.2 Mm2) via local correlation tracking. Mesogranular lanes and the central position of sinks are identified using Lagrange tracers. We find

sinks per Mm2 in the two observed regions. The sinks are located at the mesogranular vertices and turn out to be associated with (1) horizontal velocity flows converging to a central point and (2) long-lived downdrafts. The spatial distribution of magnetic fields in the quiet-Sun is also examined. The strongest magnetic fields are preferentially located at sinks. We find that 40% of the pixels with longitudinal components of the magnetic field stronger than 500 G are located in the close neighborhood of sinks. In contrast, the small-scale magnetic loops detected by Martínez González et al. in the same two observed areas do not show any preferential distribution at mesogranular scales. The study of individual examples reveals that sinks can play an important role in the evolution of quiet-Sun magnetic features.
The Dependence of the Cerean Exosphere on Solar Energetic Particle Events
Authors: Villarreal M. N. , Russell C. T. , Luhmann J. G. , Thompson W. T. , Prettyman T. H. , A’Hearn M. F. , Küppers M. , O’Rourke L. , Raymond C. A.
Published: March 2017

Observations from Earth-based ground and orbiting telescopes indicate that the Ceres’s exosphere has a time-varying water component. Evidence of a transient atmosphere was also detected by Dawn upon its arrival, inferred from the response on the Gamma Ray and Neutron Detector. That atmosphere appeared shortly after the passage of a large enhancement in the local flux of high-energy solar protons. Solar proton events have highly variable fluxes over a range of proton energies from 10 s of keV to over 100 MeV and are capable of sputtering water ice at or near the surface. Herein, we examine the fluxes of solar energetic protons measured during Earth-based attempts to detect water vapor and OH in the Ceres’ atmosphere. We find that the presence of the cerean exosphere is correlated with the inferred presence of solar energetic protons at Ceres, consistent with the event detected by Dawn.
Does Vitamin D Deficiency Effect Heart Rate Variability in Low Cardiovascular Risk Population?
Authors: Nalbant Ahmet , Vatan Mehmet Bulent , VarÄ±m Perihan , VarÄ±m Ceyhun , Kaya Tezcan , Tamer Ali
Published: March 2017

AIM: This study aimed to evaluate the cardiac autonomic dysfunction and the cardiac arrhythmia risk using heart rate variability parameters in subjects with vitamin D deficiency and low cardiovascular risk.MATERIAL AND METHODS: One hundred five consecutive individuals, 54 patients with low vitamin D status and 51 healthy controls were enrolled in this study. The overall cardiac autonomic tone was quantified by using various heart rate variability parameters included mean RR interval, mean Heart Rate, mean of standard deviations of intervals for 24 hours (SDNN), standard deviation of averages of intervals (SDANN), mean of standard deviation of intervals for 5 minutes (SDNNI), root mean square of difference of successive intervals (rMSSD) and the proportion of intervals differing more than 50 ms (pNN50) values. The 12-lead ECG was recorded from each participant, and QT intervals were measured.RESULTS: Baseline demographic profiles were similar between two groups. The heart rate variability parameters such as mean RR interval, mean HR, SDNN, SDANN, SDNNI, rMSSD and pNN50 (%) values were not significantly different in patients with low vitamin D status compared to control group. The electrocardiography analysis revealed only slight but significant prolongation of corrected QT (QTc) intervals in the control group.CONCLUSION: HRV variables were not significantly altered in patients with vitamin D deficiency in low cardiovascular risk profile group. Further studies evaluating these findings in other cohorts with high cardiovascular risk are required.
Influence of Leisure Competence and Level of Leisure Activity on Life Satisfaction in Low-Income Older Adults in Rural South Korea
Authors: Choi Jihea , Choi Jung A.
Published: March 2017

The purpose of the current study was to investigate the relationships among leisure competence, level of leisure activity, and life satisfaction in low-income older adults in rural South Korea. A sample of 137 older adults answered the study questionnaire, and significant differences in leisure competence were noted depending on age, religion, and perceived health status as well as level of leisure activity based on perceived health status and type of leisure activities. There were also notable differences in life satisfaction regarding religion and perceived health status, and a correlation among leisure competence, level of leisure activity, and life satisfaction; the influencing power of leisure competence and level of leisure activity on life satisfaction was 47%. The findings suggest that enhancement of older adults' leisure competence may increase participation in leisure activities.

[Res Gerontol Nurs. 2017; 10(2):67–75.]
Aspects de l’ésotérisme chiite dans le Corpus Ǧābirien : Les trois Livres de l’Elément de fondation
Authors: Lory Pierre
Published: March 2017

Le vaste corpus alchimique attribué à Ǧābir ibn Ḥayyān comporte d’importants éléments de doctrine chiite. L’alchimie elle-ême y est décrite comme une science « imamique », dont le but est d’aider à l’accomplissement eschatologique de l’humanité. La présente étude vise à déterminer si ces éléments sont vraiment constitutifs de la rédaction du Corpus, ou bien s’ils peuvent résulter de simples interpolations dans des textes dont le contenu est purement alchimique. Sur la base d’un texte ǧābirien ancien, le triple Kitāb al-Usṭuqus al-uss I, II et III, cet article suggère que le rôle attribué aux Imams y est fondamental et originel. Simultanément, l’idée que l’alchimiste accompli atteint, par sa recherche individuelle, la science de l’Imam conduit finalement à affaiblir la visée chiite de départ.
Sirr al-jalīqa y su influencia en el mundo árabe y persa: el comentario de ‘Awn b. al-Munḏir y su desconocida traducción persa
Authors: Karimi Zanjani Asl Mohammad
Published: March 2017

En la época islámica, Apolonio de Tiana (15-100 d.C.) era conocido tanto como “Señor de los talismanes” (ṣāḥib al-ṭilasmāt), así como filósofo neopitagórico y hermético. En su Kitāb al-Aḥŷār, Ŷabir b. Ḥayyān habla de “los defensores musulmanes de Apolonio” (aṣḥāb Balīnās al-Islāmīyūn). La referencia muestra que el trabajo más prominente de Apolonio, Sirr al-jalīqa, ya era famoso en el mundo de habla árabe desde muy temprano. Este artículo proporciona una visión general de las citas de Apolonio en las fuentes islámicas de diferentes campos y de las obras, generalmente, atribuidas a él. Además, reviso en Sirr al-jalīqa, sus influencias en las obras ŷābirianas y su recepción en la tradición ismailí. Este artículo aborda además el comentario árabe de Sirr aljalīqa de ‘Awn b. al-Munḏir (IV/X), conservado en un manuscrito único, y cuya traducción persa era hasta ahora desconocida. Dicha traducción cubre fragmentos del trabajo de Ibn al-Munḏir, no disponibles en árabe, y, por lo tanto, es una fuente sustancial para la historia de la alquimia islámica. Una edición de la traducción persa se presenta como apéndice.
Le CLES, un instrument complexe générateur de qualité ?
Authors: Gaw Stéphanie Mac
Published: March 2017

Le présent article s’intéresse à l’impact de la mise en œuvre du Cles (Certificat de compétences en langues de l’enseignement supérieur) à l’université. Nous considérerons la question de la qualité sous deux angles : d’une part, celui de l’évaluation qualitative du dispositif certificatif mis en œuvre, et d’autre part, celui de l’analyse des effets de la mise en œuvre de l’intégration du Cles dans le dispositif de formation. En empruntant la voie de la complexité, selon l’analyse faite par Morin, nous expliquerons la façon dont le changement intervient en évoquant le principe d’ « énovation » introduit par Gélinas et Fortin. Une étude sur le mode washback (Alderson et Wall) viendra confirmer la qualité prismatique du Cles, et révéler qu’il satisfait des enjeux autres que linguistiques, notamment politiques, économiques et sociaux. Enfin, par le biais d’une analyse systémique du Cles, nous démontrerons l’utilité du recours au Cles au sein du système éducatif en contexte universitaire.
Numerical Modelling of Hydrodynamic Instabilities in Supercritical Fluids
Authors: Amiroudine Sakir
Published: March 2017

The case of a supercritical fluid heated from below (Rayleigh-Bénard) in a rectangular cavity is first presented. The stability of the two boundary layers (hot and cold) is analyzed by numerically solving the Navier-Stokes equations with a van der Waals gas and stability diagrams are derived. The very large compressibility and the very low heat diffusivity of near critical pure fluids induce very large density gradients which lead to a Rayleigh–Taylor-like gravitational instability of the heat diffusion layer and results in terms of growth rates and wave numbers are presented. Depending on the relative direction of the interface or the boundary layer with respect to vibration, vibrational forces can destabilize a thermal boundary layer, resulting in parametric / Rayleigh vibrational instabilities. This has recently been achieved by using a numerical model which does not require any equation of state and directly calculates properties from NIST data base (NIST, 2000) for instance.
X-Ray Scattering Studies of Expanded Fluid Metals
Authors: Matsuda Kazuhiro , Inui Masanori
Published: March 2017

Fluid metals exhibit significant properties of thermodynamic-state dependence, since the inter-particle interaction among the constituents (electrons and ions) considerably changes depending on their thermodynamic conditions. The authors have thus far carried out X-ray scattering experiments of fluid metals in the expanded state, which have enabled us to gain insight into microscopic understanding of the structural and electronic properties of fluid metals. The purpose of this chapter is to provide intriguing aspects of fluid metals originated from the existence of conduction electrons, which distinguishes fluid metals from non-conducting fluids, through the results of fluid rubidium and mercury.
Heat Transfer and Fluid Flow of Supercritical Fluids in Advanced Energy Systems
Authors: Li Hongzhi , Zhang Yifan
Published: March 2017

This chapter aims to clarify the supercritical fluids thermal hydraulics characteristics including heat transfer, pressure drops and flow instabilities for the purpose of accurate design and efficient safe operation of advanced energy systems. At first, the convection heat transfer models considering the effect of nonlinear properties and the effect of buoyancy and acceleration have been provided and discussed. Secondly, the hydraulic resistance models for supercritical fluids have been selected and suggested for different conditions. Thirdly, the published models for supercritical flow instabilities based on four different regional partitions are summarized and clarified. At last, two typical case studies have been provided to further intuitively elaborate the thermal hydraulics of supercritical fluids within the advanced energy systems.
Supercritical Fluids and Their Applications in Power Generation
Authors: Chen Huijuan , Padilla Ricardo Vasquez , Besarati Saeb
Published: March 2017

Supercritical fluids have been studied and used as the working fluids in power generation system for both high- and low-grade heat conversions. Low-grade heat sources, typically defined as below 300 ºC, are abundantly available as industrial waste heat, solar thermal, and geothermal, to name a few. However, they are under-exploited for power conversion because of the low conversion efficiency. Technologies that allow the efficient conversion of low-grade heat into mechanical or electrical power are very important to develop. First part of this chapter investigates the potential of supercritical Rankine cycles in the conversion of low-grade heat to power, while the second part discusses supercritical fluids used in higher grade heat conversion system. The selection of supercritical working fluids for a supercritical Rankine cycle is of key importance. This chapter discusses supercritical fluids fundamentals, selection of supercritical working fluids for different heat sources, and the current research, development, and commercial status of supercritical power generation systems.
Human Factors in Context to Occupational Health and Wellbeing
Authors: Javaid Muhammad Umair , Isha Ahmad Shahrul Nizam , Nubling Matthias , Mirza Muhammad Zeeshan , Ghazali Zulkipli
Published: March 2017

A workplace never resides in isolation and hence in the workplace employees experience both psychological and social conditions which often called as psychosocial work environment. The psychosocial work environment has become continuous component in studies of occupational health and stress and encompasses concerns on the risks which generate from the psyche perceptions of the individual's concern in accordance with the risks of the societal environment. The psychosocial environment at work has a deteriorating effect on the general health of workers such as musculoskeletal disorders, mental disorders, cardiovascular diseases, stress, burnout, sickness absence, labor turnover along with the organizational outcomes like the effectiveness of work, motivation, and performance. Psychosocial factors in response to the health repair process have become increasingly important in both developed and developing countries. Such factors have not frequently been studied or addressed in developing countries even though 80 percent of the working population lives in developing countries.
Organizational Diversity
Authors: Tran Ben
Published: March 2017

An employer, according to Tran (2008), must utilize a systematic approach in predicting who is likely to succeed as a potential employee; in so doing, employers must acknowledge that potential employees, person without a disability and person with a disability, are unique individuals and not machines. Employees' performances rely not only on technical skills, knowledge, skills, and abilities (aka KSAs) but on the other characteristics, also known as the “O” in KSAOs that person without a disability and person with a disability bring themselves. Such other characteristics are more credible and reliable in predicting and determining the probability of a potential employee's success. Other characteristics, must not only be identified, but carefully examined and assessed. Validation in focusing on these other characteristics is apparent.
Workplace Bullying in Digital Environments
Authors: Salazar Leslie Ramos
Published: March 2017

Workplace bullying continues to be a prevalent workplace conflict issue in organizations around the world. The organizational reliance of communication technologies and digital media have enabled workplace bullying to evolve into workplace cyberbullying. Workplace bullying impacts individuals, relationships, organizations, and societies. For this reason, this chapter reviewed the transdisciplinary workplace bullying literature to conceptualize key constructs such as workplace bullying and workplace cyberbullying. This chapter also reviews the prevalence of workplace bullying, antecedent behaviors of workplace bullying, the consequences of workplace bullying, and the intervention approaches. Lastly, this chapter offers several recommendations for the future trends of workplace bullying scholarship.
Mastering Employee Turnover Intention in the Modern Workforce
Authors: Kasemsap Kijpokin
Published: March 2017

This chapter indicates the advanced issues of employee turnover intention; employee turnover intention, job satisfaction, and Human Resource Information System (HRIS); employee turnover intention and job burnout; employee turnover intention and mobbing; employee turnover intention, psychological capital, and work-family conflict; employee turnover intention and job engagement; and employee turnover intention in the health care industry. Turnover intention is a measurement of whether the organization's employees plan to leave their positions or whether that organization plans to remove employees from positions. Employee turnover is a natural part of business in any industry. Replacing employees can affect the organization's productivity, expenses, and overall performance. Understanding the effects of losing a high number of employees serves as a motivator to work toward reducing the employee turnover rate for the higher profits in the modern workforce.
Free and Open Source Software Movements as Agents of an Alternative Use of Copyright Law
Authors: Pina Pedro
Published: March 2017

Digital technology produced a move from a performative model to a player-as producer paradigm since it has potentiated user-generated transformative uses of intellectual works. In fact, sharing, sampling, remixing and creating new derivative content through digital network collaboration platforms are today pillars of the so-called “age of remix”. However, when unauthorized, such activities may constitute copyright infringement since the making available right and the right to make new derivative works are exclusive rights granted by copyright law. A restrictive exercise of exclusive rights may hinder the implementation of online platforms envisioned to facilitate access to knowledge and to potentiate the creation of new works. The present chapter analyzes the creation the importance of online communities of practice using free/open source software licenses like GNU GPL or Creative Commons Licenses as agents of an alternative and less rigid exercise of the powers granted by copyright law in favor of a freer system of creation and dissemination of creative works in the digital world.
The Misappropriation of Organizational Power and Control
Authors: Starr-Glass David
Published: March 2017

Workplace bullying has been the focus of much interest and research over the last forty years. This concern reflects the growing awareness of the organizational costs associated with all forms of bullying. Of particular importance is what has been called abusive supervision, which constitutes the most prevalent and destructive form of negative workplace conduct. This chapter understands abusive supervision to be a prototypical example of workplace bullying, rather than a narrower and more restricted expression of it. The chapter reviews workplace bullying, focuses on abusive managerial behavior, and understands such behavior as a misappropriation of legitimate organizational processes and dynamics for own personal ends. Bullying behavior violates the norms of workplace ethics, organizational justice, and the agency role of management. The chapter considers initiatives through which managerial bullying might be identified, remediated, and reduced.
MAQ
Authors: Rath Mamata , Pattanayak Binod Kumar
Published: March 2017

Protected data transmission in cluster based Mobile Adhoc Networks (MANETs) is a challenging mission due to the high level of node mobility of nodes and resource constrained autonomous stations during packet routing. To target this mission, a Mobile Agent based QoS (MAQ) platform has been planned in this paper that uses an improved clustering algorithm during data communication. A Mobile agent architecture has been anticipated in a way that it is coupled with the cluster head of every cluster in MANET and when priority based real time application gets notified in these clusters then the proposed system gets activated to support prioritized service to these applications including checking and monitoring the flow characteristics for real time applications. JADE (Java Agent Development Environment) based prioritized scheme at the mobile agent has been implemented in the proposed system. As this is a function oriented approach, so the overall network performance significantly improves resulting better throughput and packet delivery ratio.
Mathematical Model for Cyber Attack in Computer Network
Authors: Rao Yerra Shankar , Rauta Aswin Kumar , Saini Hemraj , Panda Tarini Charana
Published: March 2017

This investigation focuses to develop an e-SEIRS (susceptible, exposed, infectious, recovered) epidemic computer network model to study the transmission of malicious code in a computer network and derive the approximate threshold condition (basic reproduction number) to examine the equilibrium and stability of the model. The authors have simulated the results for various parameters used in the model and Runge-Kutta Fehlberg fourth-fifth order method is employed to solve system of equations developed. They have studied the stability of crime level to equilibrium and found the critical value of threshold value determining whether or not the infectious free equilibrium is globally asymptotically stable and endemic equilibrium is locally asymptotically stable. The simulation results using MATLAB agree with the real life situations.
Multi-Modal Biometric Authentication and Secure Transaction Operation Framework for E-Banking
Authors: Sabharwal Munish
Published: March 2017

The rationale of the research work is to suggest a multi-modal biometric authentication and secure transaction operation framework for E-Banking. The literature survey identifies the various types of E-Banking Channels available as on-date, the various types of biometric technologies available as on-date as well the significant metrics affecting their performance while deploying them in various different e-banking channels. The performance analysis of various types of biometric technologies based on significant metrics for Biometrics Implementation further identifies the currently implementable biometric technologies for the various different e-banking channels. Subsequently a requirement analysis of potential e-banking channels is followed by System Suitability Analysis to identify which multi-biometrics and support mechanisms are suitable for particular e-banking channels. The final conclusion suggests a viable multi-modal biometric authentication and secure transaction operation framework for various e-banking channels.
Logs Analysis of Adapted Pedagogical Scenarios Generated by a Simulation Serious Game Architecture
Authors: Callies Sophie , Gravel Mathieu , Beaudry Eric , Basque Josianne
Published: March 2017

This paper presents an architecture designed for simulation serious games, which automatically generates game-based scenarios adapted to learner's learning progression. We present three central modules of the architecture: (1) the learner model, (2) the adaptation module and (3) the logs module. The learner model estimates the progression of the development of skills targeted in the game. The adaptation module uses this estimation to automatically plan an adapted sequence of in-game situations optimizing learning. We implemented our architecture in Game of Homes, a simulation serious game, which aims to train adults the basics of real estate. We built a scripted-based version of Game of Homes in order to compare the impact of scripted-based scenarios versus generated scenarios on learning progression. We qualitatively analyzed logs files of thirty-six adults who played Game of Homes for 90 minutes. The main results highlighted the specificity of the generated pedagogical scenarios for each learner and, more specifically, the optimization of the guidance provided and of the presentation of the learning content throughout the game.
Some Video Games Can Increase the Player's Creativity
Authors: Moffat David C. , Crombie William , Shabalina Olga
Published: March 2017

It is said that playing video games might make people more creative. There is some evidence of an association, but no so far general theory about any psychological causes, or other key factors. In this study, we test the possibility that different sorts of video games may have different effects, on different types of creativity; or none at all. Three games were tested, including a sandbox and a puzzle game (Minecraft and Portal 2), and creativity was measured by the Torrance Tests of Creative Thinking (TTCT). The games were hound to have different effects, and on only some measures. We discuss possible accounts for these results, and offer practical suggestions to better control such studies in future. The strongest and most surprising result was that one particular form of creativity, flexibility, was affected much more than others. This finding awaits a theoretical explanation; but in the meantime, the implication is that video games could be used to put students into a more creative state of mind, which may be useful for their learning.
Meaningful Gamification for Journalism Students to Enhance Their Critical Thinking Skills
Authors: Huang Ling-Yi , Yeh Yu-Chu
Published: March 2017

Training in critical thinking is essential for the professional development of journalism students. To achieve this goal, this study developed a gamified platform and a blended learning curriculum. During an 18-week experimental instruction period, a series of instructional activities, which included online discussions as well as classroom lectures and discussions, were conducted to enhance 32 journalism students' critical-thinking dispositions and skills. Repeated measure analysis of variance on test scores and analyses of open questions found that the participants significantly improved their critical thinking skills and dispositions through the gamified platform with the experimental instruction in a blended learning environment. The findings suggest that providing clear goals, challenges and quests, feedback, competition and cooperation, actual grading and visible status, access/ unlocking content, onboarding time restrictions, freedom of choice, and new identities and roles, as well as avoidance of over-justification, contributes to achieving a “meaningful gamification” experience, which may further lead to self-determined learning in critical thinking.
Predicting Tweet Retweetability during Hurricane Disasters
Authors: Neppalli Venkata Kishore , Caragea Cornelia , Caragea Doina , Medeiros Murilo Cerqueira , Tapia Andrea H , Halse Shane E.
Published: March 2017

Twitter is a vital source for obtaining information, especially during events such as natural disasters. Users can spread information on Twitter either by crafting new posts, which are called “tweets,” or by using the retweet mechanism to re-post previously created tweets. During natural disasters, identifying how likely a tweet is to be retweeted is crucial since it can help promote the spread of useful information in a social network such as Twitter, as well as it can help stop the spread of misinformation when corroborated with approaches that identify rumors and misinformation. In this paper, we present an analysis of retweeted tweets from two different hurricane disasters, to identify factors that affect retweetability. We then use these factors to extract features from tweets' content and user account information in order to develop models that automatically predict the retweetability of a tweet. The results of our experiments on Sandy and Patricia Hurricanes show the effectiveness of our features.
Fe+ Implantation Induced Damage in Oxide Dispersion Strengthened Steels Investigated by Doppler Broadening Spectroscopy
Authors: Anwand Wolfgang , Leguey Teresa , Scepanovic Masa , Sanchez Fernando Jose , García-Cortés Isabel , Wagner Andreas
Published: March 2017

Open volume defects created by 1 MeV Fe+ implantation up to a damage of 15 displacements per atom into Fe14wt%Cr and into oxide dispersion strengthened (ODS) Fe14wt%Cr were investigated by positron annihilation spectroscopy, especially single Doppler broadening (DBS) and coincidence Doppler broadening spectroscopies (cDBS). The influence of W and Ti alloying elements on the evolution of defects during ion implantation were probed in addition. Whereas no effect of the W and Ti alloying constituents on the line-shape parameters S and W could be detected both before and after ion implantation, fine dispersed Y2O3 particles showed important changes in the structural properties compared to pure FeCr steel, which could be detected by DBS and cDBS. The distribution of the electron momenta in implanted ODS Fe14Cr, obtained with cDBS, shows that oxide particles form obstacles for expanded vacancy mobility and that the vacancies are localized around the oxide particles.
Hydrogen-Induced Defects in Titanium
Authors: Hruška Petr , Čížek Jakub , Lukáč František , Knapp Jan , Mašková Sylvie , Drahokoupil Jan , Melikhova Oksana , Procházka Ivan
Published: March 2017

The aim of this work was investigation of hydrogen interaction with defects in Ti. Well-annealed Ti samples were loaded with hydrogen either electrochemically or using H2 gas phase. The hydrogen content and the phase composition of hydrogen loaded samples was determined by thermogravimetric analysis and by X-ray diffraction (XRD) respectively. Positron lifetime (LT) spectroscopy was employed for investigation of defects created by hydrogen loading. High-temperature H2 gas loading led to complete transformation of the whole sample into δ-TiH2 while low-temperature H2 gas loading and the electrochemical loading resulted in a non-uniform structure with most of the hydrogen absorbed in a sub-surface layer. All hydrogen-loaded samples exhibit positron lifetime component of ≈ 170 ps corresponding to positrons trapped at dislocations. Vacancy clusters were observed in the electrochemically loaded sample and the H2 gas phase loaded sample at low temperature.
Study of Defects Introduced by 2 and 9 MeV Electron Irradiation in B2 Type Fe-Al Alloy
Authors: Ueno Youhei , Iwase Akihiro , Ohsawa Kazuhito , Xu Qiu , Sato Koichi , Saitoh Yuichi , Hori Fuminobu
Published: March 2017

It is well known that intermetallic compound alloys possibly include more than two types of vacancies basically, that is A-vacancy and B-vacancy in A-B compound alloy. Although MeV ordered electron irradiation produces vacancies and interstitials, the threshold energy of displacement for each elemental atom in intermetallic alloys is not necessarily same. Then the defect type introduced by the irradiation depends on electron energy. In this study, we performed positron annihilation lifetime and Doppler broadening measurements for different energy of electron irradiated B2 type Fe50%Al alloy. The values of positron annihilation lifetime for this alloy after 2 and 9 MeV electron irradiation were 200 and 172 psec, respectively. Also, the Doppler broadening parameters S and W show difference for this alloy with different energy of electron irradiation. These results suggest that different types of vacancy were induced into Fe-Al compound alloy by electron irradiation with different energies.
Structural Relaxation of Open Volume in Hyper-Eutectic Zr-Cu-Al Bulk Amorphous Alloys Measured by Positron Annihilation
Authors: Ishiyama Taishi , Kobayashi Kazukui , Yokoyama Yoshihiko , Konno Toyohiko J. , Iwase Akihiro , Hori Fuminobu
Published: March 2017

The Zr-Cu-Al bulk amorphous (BA) alloys, which have no long-range ordered structure, possess various properties such as high strength and toughness with compositional dependence. In the present study, in order to estimate the natures of local structure change and relaxation behavior of hyper-eutectic BA alloys during annealing, positron annihilation measurements and density measurement have been performed for hyper-eutectic Zr-Cu-Al BA alloys with annealing. The enthalpy relaxation and structural relaxation was also measured by differential scanning calorimetry (DSC) measurement. These results show that the relaxation process of free volume containing in hyper-eutectic BA alloys is different from that in hypo-eutectic alloys.
Study the Effect of Plastic Deformation in 8006 Al-Alloys by Positron Lifetime Spectroscopy, Vickers Hardness and X-Ray Diffraction
Authors: Badawi Emad A. , Abdel-Rahman M.A. , Salah Mohammed , Abdel-Rahman Mohamed
Published: March 2017

Due to the great effect of defects on the properties of the material including strength, ductility, resistivity and opacity, there are many techniques that are used in defect detecting. Positron annihilation spectroscopy (PAS), Vickers hardness, and X-ray diffraction were used to study the influence of plastic deformation on the properties of 8006 Al-alloy in this work. An increase in the positron lifetime and Vickers hardness with a bit Broadening of XRD peaks was observed with increasing the degree of deformation reflecting a large dislocation density produced by plastic deformation.
Irradiation Induced Defects by Fe-Ion in 316L Stainless Steel Studied by Positron Annihilation Spectroscopy
Authors: Cao Xing Zhong , Lu Er Yang , Jin Shuo Xue , Gong Yi Hao , Hu Yuan Chao , Zhu Te , Zhang Peng , Wei Long , Wang Bao Yi
Published: March 2017

Solution annealed type 316L austenitic stainless steels were irradiated using 2 MeV Fe ions at room temperature. The implanted fluences were 2×1012 ions/cm2 and 1×1013 ions/cm2, respectively. Variable mono-energetic positron beam was performed to characterize the evolution of microstructure and irradiation induced defects. Results show that large amount of vacancy defects formed after heavy ion irradiation. In which, some of mono-vacancies might migrate to form small-sized clusters at room temperature. After irradiation, implanted Fe atoms mainly be interstitials atoms, but some Fe atoms might recombine with vacancies due to their high mobility, which could decrease the defect concentration, effectively.
Strain-Rate Dependence of Vacancy Cluster Size in Hydrogen-Charged Martensitic Steel AISI410 under Tensile Deformation
Authors: Sugita Kazuki , Mutou Yasumasa , Shirai Yasuharu
Published: March 2017

The strain-rate dependence of vacancy cluster sizes in hydrogen-charged martensitic steel AISI410 under tensile deformation was investigated using positron lifetime spectroscopy. The vacancy-cluster sizes in hydrogen-charged samples tended to increase with decreasing strain rates during the tensile deformations. The vacancy-cluster sizes significantly correlated to the tensile elongations to fracture. It was revealed that the presence of large-sized vacancy-clusters can cause the degradation of mechanical properties and followed by brittle fracture.
Vacancy-Type Defects in GaN for Power Devices Probed by Positron Annihilation
Authors: Uedono Akira , Ishibashi Shoji , Oshima Nagayasu , Suzuki Ryoichi
Published: March 2017

Native defects and ion-implantation induced defects in GaN were studied by means of positron annihilation. Measurements of Doppler broadening spectra of the annihilation radiation for GaN layers grown on Si substrates showed that optically active vacancy-type defects were formed in the layers. Charge transition of the defects due to electron capture occurred when the layers were irradiated by photons with energy above 2.7 eV. It was found that Ti deposition and subsequent annealing introduced vacancy clusters. We also characterized vacancy-type defects in Mg-implanted GaN. The major defect species of vacancies introduced by Mg-implantation was a complex between Ga-vacancy (VGa) and nitrogen vacancies (VNs). After annealing above 1000C, these defects started to agglomerate, and the major defect species became (VGa)2 coupled with VNs. Through this work, we have demonstrated that positron annihilation spectroscopy is a powerful tool for characterizing vacancy-type defects in GaN for power devices applications.
Studies of Microstructure and Electro-Magnetic Transport Property of La0.67Ca0.33MnO3 Ceramic
Authors: Xu Shou Lei , Xie Er Juan , Cao Xiu Qing , Huang Yu Yang , Xiong Ding Kang , Deng Wen
Published: March 2017

The positron annihilation techniques and X-ray diffraction have been used to study the microstructure of the La0.67Ca0.33MnO3 ceramics prepared by the solid-state reaction method at different sintered temperatures (T=1573K, 1623K, 1673K, 1723K, 1773K, 1823K). And the electro-magnetic transport behavior of the samples was measured by VSM and Resistivity modular on PPMS. According to these results, all samples show a perovskite structure, the ferromagnetic-paramagnetic and metal-insulator transitions occur at the transition temperature Tc and TMI, respectively, which is almost the same. For La0.67Ca0.33MnO3 sintered at 1673K, the mean positron lifetime is the largest, the maximum value of the magnetization is achieved on the magnetization-temperature curve at H=0.2mT, while the transition temperature occurs at about 244K.
Radiation-Induced Defects in Si after High Dose Proton Irradiation
Authors: Funtikov Yurii V. , Dubov Leonid Yu. , Shtotsky Yurii V. , Stepanov Sergey V.
Published: March 2017

Experiments on investigation of the radiation defects produced as a result of high energy proton irradiation of single crystal Si wafers are carried out. Parameters of the proton irradiation facility are presented. It is shown that the most efficient radiation defect formation correlates with the position of the Bragg peak of ionization losses. LT spectra were measured just after irradiation and then after keeping Si samples during 3 months of at room T. We did not observe any variation of the number density of the defects, except for the 7th wafer, where most part of protons was stopped. An efficient annealing of the vacancy-type defects starts at temperatures slightly lower than 100 °C (during 10 min). Annealing at about 700 °C leads to recovering of the monoexponrntial shape of the LT spectra.
Modulation of the Dielectric Properties of CaCu3Ti4O12 System with Gd-Substitution
Authors: Chen Zhen Ping , He Hui Fang , Li Tao , Dai Hai Yang , Chen Zhi Quan
Published: March 2017

To specify the effects of modulating mechanism of Gd substitution on the dielectric properties for Ca1-xGdxCu3Ti4O12 system, the XRD, SEM and positron positron annihilation technique have been implemented. The results display that both grain size and vacancy-type defect concentration play important roles in controlling the dielectric properties of CaCu3Ti4O12. The dielectric properties are improved by adding an appropriate amount of Gd additives (x=0.01) but weakened by higher Gd doping content since this is closely related to the grain size and concentration of vacancy-type defect in the samples.
Asymmetric Positron Interactions with Chiral Quartz Crystals?
Authors: van Horn J. David , Wu Fei , Corsiglia Gerald , Jean Yan Ching
Published: March 2017

We have studied the interaction of the positron with chiral left-or right-handed quartz crystals. In Doppler-broadening experiments, using a mono-energetic positron beam there is a differential depth profile for positrons implanted in LH or RH z-cut quartz as identified by a shape parameter (S). Further, in bulk positron annihilation lifetime spectroscopy (PALS) experiments, the lifetime (τ 2) attributed to free annihilation of the positron interacting with the chiral lattice exhibits a larger value for the LH quartz, and the associated intensity (I2) is also significantly different—RH quartz is consistently 10% greater than the LH crystal. The τ3 lifetime and its intensity, I3, attributed to positronium interacting with defects in the quartz, also appears to exhibit differences between the enantiomeric sets of crystals. These observations may demonstrate chiral recognition using a positron annihilation technique, pave the way for a broad range of positron experiments, and may help inform hypotheses of chirality recognition, selection, or induction by beta radiation.
Low-Energy Ps-Xe Scattering Analyzed Using a Modified Effective Range Theory
Authors: Shibuya Kengo , Saito Haruo
Published: March 2017

We have investigated positronium‒xenon collisions at energies below 100 meV to find a strong temperature dependences of the annihilation rates. A partial wave analysis based on a modified effective range theory (MERT) is tested to explain the temperature dependences and to find significant contributions of the p-wave scattering component. The fact that MERT works well for analyzing positronium‒xenon collisions indicates that positronium is polarized during the collisions as proposed by other theoretical and experimental researchers.
Positron Annihilation in TaN Thin Sputtering Films Prepared with Various N2 Partial Pressures
Authors: Liu Jian Dang , Gu Bing Chuan , Fang Jia Jie , Ye Bang Jiao
Published: March 2017

Tantalum nitride (TaN) thin films were deposited using magnetron sputtering method under different N2/Ar ratio condition. Slow positron beam was used to analyze the microstructure of those films. The results show that the films which deposited at low N2/Ar flow ratio contain more vacancy-like defects, and the corresponding S parameter is relatively large. The sheet resistance measurement displays that ohms-per-square greatly increase with increased N2/Ar ratio. And the reasons could be related to nonstoichiometry-induced vacancies and lattice distortions.
Defect Characterization in Thermoelectric Zn-Sb Systems by Positron Annihilation
Authors: Zhang Ting , Zhou Kai , Chen Zhi Quan
Published: March 2017

Positron lifetimes and momentum distributions of annihilating electron-positron pairs have been calculated for vacancies in ZnSb and Zn4Sb3. The calculated positron lifetimes for bulk ZnSb and Zn4Sb3 are 203 ps and 208 ps, and for VZn in ZnSb and Zn4Sb3 are 249 ps and 237 ps respectively. The calculated momentum distribution results indicate the VZn in both ZnSb and Zn4Sb3 has less characterization from elemental Zn. Using coincidence Doppler broadening spectra combined with lifetime measurements can reveal the vacancy structure in ZnSb and Zn4Sb3.
Microstructure and Defects of MgO/ZrO2 Nanocrystals Investigated by Positron Annihilation Spectroscopy
Authors: Wang Jia Heng , Shi Jian Jian , Yang Wei , Zhu Zhe Jie , Wu Yi Chu
Published: March 2017

Pure MgO, ZrO2 and mixture MgO/ZrO2 nanocrystals were annealed in air from 100 to 1200°C. Variation of the microstructure and defects was investigated by positron lifetime spectroscopy and X-ray diffraction. The experiment results showed that the average positron lifetime of mixture MgO/ZrO2 was more larger than that of single phase MgO and ZrO2, and decreased with the increasing annealing temperature. Thermal annealing below 600°C, the movement of grain boundaries mainly led a reduce of the number of microvoids, and vacancy defects began to recover due to the growth of MgO nanoparticles after annealing between 600 to 900°C. Furthermore, ZrO2 nanoparticles began to grow above 900°C, meanwhile the recovery of vacancy and vacancy clusters in MgO/ZrO2 nanoparticles are restrained because of synergic effect between MgO and ZrO2 nanoparticles.
Characterization of Polysulfone/TiO2 Composite Membrane Modified by Plasma
Authors: Chen Zhe , Yin C. , Wang S. , Ito Kenji , Fu Q.M. , Deng Q.R. , Lin Z.D. , Fu P. , Zhang Y. , Liu Z.T.
Published: March 2017

In order to enhance the surface anti-fouling property of separation membrane, TiO2/polysulfone (PSF) membrane was prepared by the phase inversion method, and the surface was treated by oxygen plasma to obtain a composite membrane with photo catalysis activity. To evaluate the effect of oxygen plasma on the surface modification, positron annihilation γ-ray spectroscopy coupled with a positron beam was utilized to probe the surface feature, while the catalysis evaluation system was employed to study the anti-fouling activity of the membrane. The results indicate that with increasing plasma treatment time, the membrane exhibits higher S parameter in the lower energies, while the photo catalysis activity is strengthened. It can be concluded that plasma technique can improve the photo catalysis activity of the composite membrane.