bluuebunny/crossref_metadata_2025_split huggingface dataset:
Bayesian bootstrap aggregation for tourism demand forecasting
Authors: Song Haiyan , Liu Anyu , Li Gang , Liu Xinyang 
Published: April 2021

AbstractLimited historical data are the primary cause of the failure of tourism forecasts. Bayesian bootstrap aggregation (BBagging) may offer a solution to this problem. This study is the first to apply BBagging to tourism demand forecasting. An analysis of annual and quarterly tourism demand for Hong Kong shows that BBagging can, in general, improve the forecasting accuracy of the econometric models obtained using the general‐to‐specific (GETS) approach by reducing, relative to the ordinary bagging method, the variability in the posterior distributions of the forecasts it generates.
A dynamic simulation framework for CT perfusion in stroke assessment built from first principles
Authors: Divel Sarah E. , Christensen Soren , Segars William P. , Lansberg Maarten G. , Pelc Norbert J. 
Published: April 2021

PurposePhysicians utilize cerebral perfusion maps (e.g., cerebral blood flow, cerebral blood volume, transit time) to prescribe the plan of care for stroke patients. Variability in scanning techniques and post‐processing software can result in differences between these perfusion maps. To determine which techniques are acceptable for clinical care, it is important to validate the accuracy and reproducibility of the perfusion maps. Validation using clinical data is challenging due to the lack of a gold standard to assess cerebral perfusion and the impracticality of scanning patients multiple times with different scanning techniques. In contrast, simulated data from a realistic digital phantom of the cerebral perfusion in acute stroke patients would enable studies to optimize and validate the scanning and post‐processing techniques.MethodsWe describe a complete framework to simulate CT perfusion studies for stroke assessment. We begin by expanding the XCAT brain phantom to enable spatially varying contrast agent dynamics and incorporate a realistic model of the dynamics in the cerebral vasculature derived from first principles. A dynamic CT simulator utilizes the time–concentration curves to define the contrast agent concentration in the object at each time point and generates CT perfusion images compatible with commercially available post‐processing software. We also generate ground truth perfusion maps to which the maps generated by post‐processing software can be compared.ResultsWe demonstrate a dynamic CT perfusion study of a simulated patient with an ischemic stroke and the resulting perfusion maps generated by post‐processing software. We include a visual comparison between the computer‐generated perfusion maps and the ground truth perfusion maps. The framework is highly tunable; users can modify the perfusion properties (e.g., occlusion location, CBF, CBV, and MTT), scanner specifications (e.g., focal spot size and detector configuration), scanning protocol (e.g., kVp and mAs), and reconstruction parameters (e.g., slice thickness and reconstruction filter).ConclusionsThis framework provides realistic test data with the underlying ground truth that enables a robust assessment of CT perfusion techniques and post‐processing methods for stroke assessment.
A study on understanding the physical mechanism of change in ultrasonic envelope statistical property during temperature elevation
Authors: Omura Masaaki , Takeuchi Michio , Nagaoka Ryo , Hasegawa Hideyuki 
Published: April 2021

PurposeOur previous studies demonstrate that the variation in ultrasonic envelope statistics is correlated with the temperature change inside scattering media. This variation is identified as the change in the scatterer structure during thermal expansion or contraction. However, no specific evidence has been verified to date. This study numerically reproduces the change in the scatterer distribution during thermal expansion or contraction using finite element simulations and also investigates how the situation is altered by different material properties.MethodsThe material properties of a linear elastic solid depend on the thermal expansion coefficient, thermal conductivity, specific heat, and initial scatterer number density. Three‐dimensional displacements, calculated in the simulation, were sequentially used to update the positions of the randomly distributed scatterers. Ultrasound signals from the scatterer distribution were generated by simulating a 7.5‐MHz linear array transducer whose specifications were the same as those in the experimental measurements of several phantoms and excised porcine livers. To represent the change in the envelope statistical feature, the absolute value of the ratio change in the logarithmic Nakagami (NA) parameter, , at each time was calculated as a value normalized with the initial NA parameter.ResultsThe change in the scatterer number density relates to the volume change during temperature elevation. The magnitude of the shift against the temperature change increases depending on the higher thermal expansion coefficient. In contrast, the relationship between and the scatterer number density is similar with any material property. Additionally, the changes in obtained by several experimental phantoms with low to high scatterer number densities are comparable with the numerical simulation results.ConclusionsThe change in is indirectly related to the change in the scatterer number density owing to the volume change during thermal expansion or contraction.
Copper metal‐organic framework toward flame‐retardant enhancement of thermoplastic polyurethane elastomer composites based on ammonium polyphosphate
Authors: Chen Xilei , Chen Xihong , Li Shaoxiang , Jiao Chuanmei 
Published: April 2021

In this article, copper metal‐organic framework (MOF‐Cu) was synthesized and used as synergism with ammonium polyphosphate (APP) to prepare flame‐retardant thermoplastic polyurethane (TPU) composites. The synergistic flame‐retardant effects between MOF‐Cu and APP in TPU composites were studied by cone calorimeter (CCT), limiting oxygen index tests (LOI), vertical burning tests (UL‐94), smoke density test, etc. The results showed that MOF‐Cu had some flame‐retardant effects on TPU, and APP had good flame retardancy in TPU/APP composites. And, the flame retardancy of TPU/APP was further enhanced when MOF‐Cu was used as synergism with APP. It has been found that the peak heat release rate (pHRR) and total heat release (THR) values of TPU/Cu0.0625 sample were reduced by 26.0% and 1.3% compared with pure TPU, respectively. And the pHRR and THR values of TPU/APP sample were reduced by 70.3% and 15.8% compared with pure TPU. In the case of TPU/APP/Cu0.0625 sample, the pHRR and THR values were furtherly reduced by 19.2% and 63.4% compared with TPU/APP, because of the minor amount of MOF‐Cu. It has been found MOF‐Cu cannot suppress the smoke release and reduce the total smoke release (TSR) value. However, 0.125 wt% MOF‐Cu can make the TSR value of TPU/APP/Cu0.125 sample reduce to 227.8 m2/m2, which was 23.4% lower than that of TPU/APP. The good synergistic flame‐retardant effect between MOF‐Cu and APP was obtained by the catalyzing carbonization process to form the char residue layer with high graphitization and expansion degree.
Mechanical properties and foaming behavior of polypropylene/elastomer/recycled carbon fiber composites
Authors: Ghanbari Abbas , Seyedin Shayan , Nofar Mohammadreza , Ameli Amir 
Published: April 2021

AbstractResearch on lightweight products for transportation industry, to address fuel efficiency and lower carbon footprint, has attracted great attention due to public environmental awareness. Polymer composites containing carbon fiber are boosted by automotive original equipment manufacturers (OEMs) as a replacement for steel. However, their high cost has generated interest to find cost‐effective alternatives. In this report, a recycled carbon fiber and an elastomer are introduced to polypropylene impact copolymers to modify matrix properties in terms of strength and toughness. Fractography analysis is carried out to elucidate the failure mechanisms governing the mechanical performance of the compatibilized carbon fiber reinforced thermoplastic polyolefin (TPO) composites. The results suggest that for the TPO composites, toughened by an ethylene‐1‐octene copolymer, the complex interplay of intrinsic and extrinsic toughnesses in impact resistance is predominantly governed by the presence of the fibers. Incorporating 20 wt% recycled carbon fibers into the matrix resulted in an improvement of the heat distortion temperature (HDT) by 100 °C, and ~ 3.5 and ~ 11.5 times enhancements in tensile strength and stiffness, respectively. Moreover, microcellular foams with expansion ratios higher than 11 and 5 were achieved for the neat samples and reinforced composites, respectively, confirming the foamability of composites with such a high carbon fiber content.
Function‐based adaptive exponentially weighted moving average dispersion control chart
Authors: Arshad Asma , Noor‐ul‐Amin Muhammad , Hanif Muhammad 
Published: April 2021

AbstractIn this study, a new process dispersion monitoring control chart is proposed based on a function‐based adaptation to select the smoothing constant value, named as a function‐based adaptive exponentially weighted moving average (EWMA) dispersion control chart. It is suggested to track shift ranges first expected in process dispersion by opting for smoothing constant computation with the help of a function. The shift magnitude assessment is made by an unbiased estimator that determines the smoothing constant value through the proposed function. The enhanced efficiency of the proposed chart can be assessed in terms of smaller run‐length profiles, which are determined through Monte Carlo simulations. The proposed chart is compared with the existing adaptive EWMA dispersion chart, and it turned out to perform substantially efficiently in detecting all kinds of decreasing and increasing process dispersion shift magnitudes. Moreover, a real‐life dataset application is explained in the example section to elaborate on the ease of implementation in the real‐life scenario.
Understanding Within‐ and Cross‐Language Relations Among Language, Preliteracy Skills, and Word Reading in Bilingual Learners: Evidence From the Science of Reading
Authors: Gottardo Alexandra , Chen Xi , Huo Michelle Ru Yun 
Published: April 2021

ABSTRACTResearch has shown that language and literacy skills in a first language (L1) are related to performance in a second language (L2) and that these relations are reciprocal. However, cross‐linguistic skills related to word reading are influenced by numerous factors. These include linguistic factors such as the specific language and literacy skills being examined and the languages being compared. They also include societal/contextual factors, such as the linguistic and educational contexts where learners reside. Specifically, contextual factors include the use of the L1 and L2 in the curriculum (e.g., immersion, dual language, heritage language, available supports), teaching methods, and whether the L1 and L2 are societal languages. Research based on the science of reading for bilinguals has shown that phonological awareness is highly related across languages, whereas other language skills have shown differential levels of relations to reading. Word‐reading skills are also related, but these relations are more complex and are due to linguistic factors such as script and linguistic typology and societal/contextual factors, such as instruction and exposure to each language, which are consistent with various theories. Consideration of a wider range of L1s and L2s and specific contextual/societal factors should be included more systematically. Additionally, learner experiences and specific L1 and L2 variables should be considered in educational decisions.
A case of reactive hypoglycemia caused by Kampo medicine
Authors: Yamasaki Genzo 
Published: April 2021

ABSTRACTCaseReactive hypoglycemia can occur due to postprandial insulin hypersecretion. However, no Kampo medicine is known to cause this effect. Herein, we describe a case of reactive hypoglycemia that occurred postprandially as an effect of Kampo medicine. A 42‐year‐old woman was admitted because of chest pain. We prescribed saikokaryukotsuboreito, following which the patient's symptoms improved. However, after 9 months, she experienced persistent fatigue after developing a cold. Therefore, we changed the prescription to hochuekkito and keishikaryukotsuboreito. Nevertheless, discomfort in the epigastric region and back pain developed within a few hours after administration of these medications.OutcomeResults of 75 g oral glucose tolerance test (OGTT) showed excessive insulin secretion, potentially as a result of changing Kampo administration. Therefore, the treatment was changed back to saikokaryukotsuboreito, which resolved the postprandial symptoms. Moreover, the insulin hypersecretion disappeared on subsequent 75 g OGTT.ConclusionThe promotion of gastric peristaltic function as an effect of Kampo may cause reactive hypoglycemia.
Scales of Change and Diagnostic Contradictions: Shifting Relations Between an Emigrant Community and Its Diaspora
Authors: Trémon Anne-Christine 
Published: April 2021

AbstractThe specific question this chapter addresses is how to account ethnographically for change that unfolds on spatial and temporal scales larger than those of the ethnographic field study without opposing the local site to global forces. My research engages a processual approach which examines the effects of China’s transformations and the creation of the Shenzhen Special Economic Zone on the relationship between the members of a former emigrant community and their diaspora. I propose an analytical distinction between two relational dimensions of scale in which social action can be considered: scale as the scope of social systems or chains of interdependence that extend in space and time and in which actions and interactions take place, and scale as valence, i.e., the desirability of scale defined relative to other scales, generating “scalar projects.” I focus on how contradictions in the collected field materials are telling signs of accelerated change that generate conflicts of scale, and use such “diagnostic contradictions” as a starting point for understanding how people attempt to make sense of rapid change and reconceptualize the valence of local and global scales.
Rescuing Biography from the Nation: Discrete Perspectives on Political Change in Morocco
Authors: Bono Irene 
Published: April 2021

AbstractPolitical biographies and the narratives of the nation-state may exert a reciprocal fictional influence: the nation as imagined community is often embodied in the biographies of imaginary actors. Since the 2004 launch of the transitional justice process in Morocco this tendency has led to increased attention for the stories of the victims of the violations committed by the State between 1956 and 1999 as if they were the main witnesses of the political change. In parallel, the protagonists of the nationalist struggle that led to independence from the French protectorate in 1956 have been acknowledged without, apparently, feeling it necessary to hear what they have to say about it. This chapter reflects on theoretical and methodological perspectives that allow the use of biography to explore political change beyond taken-for-granted conceptions of the nation-state and its trajectories of change. Reflecting on the relationship that developed between the author and a single actor called Abk, who wanted to tell his life story, the chapter proposes the writing of biography as a form of archival research and a fieldwork practice for exploring memory. It shows how paying attention to personal ways of conserving memory and remembering enables us to approach politics beyond predefined horizons of change without seeing a priori social configurations as ineluctable givens. Such a perspective, which the author calls “discrete”, suggests considering politics as a phenomenon that is difficult to fit into formal models of explanation, and taking subjectivity, the variability of life paths and contingency as relevant objects of inquiry for understanding political change.
“A Proper House, Not a Barn”: House Biographies and Societal Change in Urban Kyrgyzstan
Authors: Isabaeva Eliza 
Published: April 2021

AbstractIn Kyrgyzstan, scholars disagree about the outcomes of the Tulip Revolution of 2005: while some argue that the revolution has not resulted in noteworthy changes in the country, others see it as the beginning of major political change. To trace the materiality of such change it is necessary to look at the micro-level of a society, as this chapter does by focusing on the house as the unit of analysis for a close study of change. It examines the gradual transformation of dwellings in Ak Jar, an illegal squatter settlement on the northern edge of Kyrgyztan’s capital city Bishkek. The immediate aftermath of the Tulip Revolution saw the emergence of numerous illegal squatter settlements on the outer fringes of the city. Ak Jar, the largest of these, has some 15,000 inhabitants who arrived in Bishkek as internal migrants in search of employment. The dwellings in Ak Jar have changed over the course of time: most began as small mud shacks, and changed when a family generated enough money to improve and expand them. The development of these houses was central for the gradual official recognition of the illegal settlements that emerged in post-revolutionary Kyrgyzstan. House biographies are therefore intrinsically tied to wider developments in Kyrgyz society and throw new light on the ruptures, power struggles, and consolidation of power relations after the Tulip Revolution.
Spatializing Social Change: Artisanal and Small-Scale Gold Mining in Upper Guinea
Authors: Dessertine Anna 
Published: April 2021

AbstractThis chapter proposes a spatial perspective on the analysis of social change in the making via a study of artisanal and small-scale gold-mining sites in Guinea based on twenty-two months of fieldwork between 2011 and 2019 in the region of Upper Guinea, where increasing numbers of inhabitants have been circulating between artisanal and small-scale mining sites to search for gold since the price of gold rose between 2008 and 2012. The chapter starts by discussing artisanal and small-scale mining spaces through the notion of hotspots of transition, insisting on their liminal character. This liminality is analyzed as a spatial framework in which new opportunities emerge regarding gender—women’s adoption of what is considered masculine behavior, for instance—and where instantaneity is more privileged than continuity in some actions, such as those associated with consumption. More generally, it shows how the potential for change in artisanal and small-scale mining spaces is closely linked to their ephemeral nature. The relationship between space and temporality is more explicitly discussed in the second part of the chapter, which explores how the ephemerality of artisanal and small-scale mining spaces has recently been challenged by the Guinean government’s move to control mining mobility and fix mining sites spatially by delimiting legal mining territories. Since 2015–2016, multiple military operations have been conducted to expel miners from land for which the Guinean State has given industrial companies legal permits to prospect for and mine gold. This part of the chapter analyzes the socio-spatial consequences of this situation and shows that perceptions of time and of social change are constructed by the forms that space take.
Cross-National Variation in the Link Between Parental Socio-Economic Status and Union Formation and Dissolution Processes
Authors: Brons M. D. 
Published: April 2021

AbstractThe main objective of this chapter is to understand the link between parental socio-economic status (SES) and union formation and dissolution processes from a cross-national comparative perspective. According to the Second Demographic Transition (SDT) theory, it can be expected that the impact of parental background on these union dynamics differs across societal contexts. Integrated results from prior studies using meta-analytical tools indicate that in many European countries, young adults from advantaged backgrounds delay their first co-residential union and have a higher risk to dissolve their union compared to young adults from disadvantaged backgrounds. The strength of this link between parental SES and union dynamics varies across countries. There is suggestive evidence that the link between parental SES and union dynamics is weakest in North-Western European countries that are most advanced in the SDT. However, next to these SDT-related indicators that focus more on cultural change, institutional country-level indicators, like the extent of educational expansion, and economic country-level indicators, such as the level of economic uncertainty, might also play a role.
Meta-Analysis and Meta-Regression: An Alternative to Multilevel Analysis When the Number of Countries Is Small
Authors: Liefbroer Aart C. , Zoutewelle-Terovan Mioara 
Published: April 2021

AbstractHierarchically nested data structures are often analyzed by means of multilevel techniques. A common situation in cross-national comparative research is data on two levels, with information on individuals at level 1 and on countries at level 2. However, when dealing with few level-2 units (e.g. countries), results from multilevel models may be unreliable due to estimation bias (e.g. underestimated standard errors, unreliable country-level variance estimates). This chapter provides a discussion on multilevel modeling inaccuracies when using a small level-2 sample size, as well as a list of available alternative analytic tools for analyzing such data. However, as in practice many of these alternatives remain unfeasible in testing hypotheses central to cross-national comparative research, the aim of this chapter is to propose and illustrate a new technique –the 2-step meta-analytic approach – reliable in the analysis of nested data with few level-2 units. In addition, this method is highly infographic and accessible to the average social scientist (not skilled in advanced simulation techniques).
Modeling the Genesis of Life Courses
Authors: Han Sapphire Yu , Elzinga Cees H. 
Published: April 2021

AbstractLife course research has been dominated by methods and models that focus on the description of life course patterns and on the causal patterns between agency- and structure-related variables on the one hand and, on the other hand, outcomes in later life. Little attention has been paid to modelling the driving force, the mechanism, that generates the chain of successive events and stages of the life course: the sequences of individual decisions pertaining to all facets of the life course. This paper presents the minimal requirements that models should satisfy in order to be considered as life course generating models. The paper then proposes Hidden Markov Models as one of the main building blocks of life course generating models and discusses a few applications of these models in the domains of family formation, school-to-work transition and their interaction.