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2021 ◽  
Vol 21 (5) ◽  
pp. 79-88
Author(s):  
Chae Yeon Han ◽  
Woo Sik Kim ◽  
Dong Keun Yoon

This study aims to analyze differences in domestic and international disaster research trends. We first performed topic modeling on 20,477 papers published in three domestic and 12 international journals over the last 21 years (2000-2020) and then visualized the trends. Based on the extracted topics and keywords, we analyzed keyword networks using Gephi. Research in domestic journals mainly revolved around natural disasters like earthquakes, fire, and flooding. In contrast, international journals spotlighted policy-based topics such as disaster governance and community resilience. Meanwhile, globally, building and civil engineering research has shrunk in recent five years (we refer to this as a cold topic). On the other hand, in the past five years, fire and flood research has appeared more frequently in domestic journals, while international journals have presented more articles on community resilience, risk perception, and behavior (we refer to this as a hot topic). Results of this research can provide suggestions about the directions domestic disaster research should develop in the future.


2021 ◽  
Vol 17 (10) ◽  
pp. e1008899
Author(s):  
Susanne Pettersson ◽  
Martin Nilsson Jacobi

Understanding ecosystem stability and functioning is a long-standing goal in theoretical ecology, with one of the main tools being dynamical modelling of species abundances. With the help of spatially unresolved (well-mixed) population models and equilibrium dynamics, limits to stability and regions of various ecosystem robustness have been extensively mapped in terms of diversity (number of species), types of interactions, interaction strengths, varying interaction networks (for example plant-pollinator, food-web) and varying structures of these networks. Although many insights have been gained, the impact of spatial extension is not included in this body of knowledge. Recent studies of spatially explicit modelling on the other hand have shown that stability limits can be crossed and diversity increased for systems with spatial heterogeneity in species interactions and/or chaotic dynamics. Here we show that such crossing and diversity increase can appear under less strict conditions. We find that the mere possibility of varying species abundances at different spatial locations make possible the preservation or increase in diversity across previous boundaries thought to mark catastrophic transitions. In addition, we introduce and make explicit a multitude of different dynamics a spatially extended complex system can use to stabilise. This expanded stabilising repertoire of dynamics is largest at intermediate levels of dispersal. Thus we find that spatially extended systems with intermediate dispersal are more robust, in general have higher diversity and can stabilise beyond previous stability boundaries, in contrast to well-mixed systems.


PLoS ONE ◽  
2021 ◽  
Vol 16 (10) ◽  
pp. e0259216
Author(s):  
Satoru Yoshimura ◽  
Satoshi Sugimoto ◽  
Takae Takeuchi ◽  
Kensuke Murai ◽  
Masato Kiuchi

We proposed an experimental methodology for producing films on substrates with an ion beam induced chemical vapor deposition (IBICVD) method using hexamethyldisilazane (HMDS) as a source material. In this study, both HMDS and ion beam were simultaneously injected onto a Si substrate. We selected Ar+ and N+ as the ion beam. The energy of the ion beam was 101 eV. Temperature of the Si substrate was set at 540 °C. After the experiments, films were found to be deposited on the substrates. The films were then analyzed by Fourier transform infrared (FTIR) spectroscopy, stylus profilometer, X-ray diffraction, atomic force microscopy, and X-ray photoelectron spectroscopy (XPS). The FTIR and XPS results showed that silicon carbide films containing small amount of nitrogen were formed when Ar+ ions were injected in conjunction with HMDS. On the other hand, in the cases of N+ ion beam irradiation, silicon nitride films involving small amount of carbon were formed. It was noted that no film deposition was observed when HMDS alone was supplied to the substrates without any ion beam injections.


2021 ◽  
Vol 3 (2) ◽  
pp. 156-164
Author(s):  
M. Salim Anwar ◽  
Retno Dwiyanti

Academic procrastination is one of the problems experienced by students, which is caused by feeling tired or bored. While on the other hand, students need the ability to organize themselves to achieve their goals. This study aims to determine the effect of self-regulated learning on academic procrastination in class XI students of SMA Negeri 2 Purbalingga. The hypothesis proposed in this study is that self-regulated learning has a significant effect on academic procrastination in class XI students of SMA Negeri 2 Purbalingga. The sample of this research is the students of class XI SMA Negeri 2 Purbalingga with a total of 80 students. Data were collected by using several instruments in the form of academic procrastination scale and self-regulated learning scale. The academic procrastination scale has a reliability of 0.741 and a self-regulated learning scale of 0.744. The results of the analysis show that the calculated F is 146.734 with a coefficient of p = 0.000 (p<0.01), t = -12.113. It can be concluded that the hypothesis is accepted, namely that there is a significant influence between self-regulated learning on academic procrastination in class XI students of SMA Negeri 2 Purbalingga and self-regulated learning. It has an effect of 65.3% on academic procrastination (R = square = 0.653). For educational institutions, the results of this study can be a contribution to the thought of psychology to design various learning methods that lead to the concept of self-regulation in student learning in order to reduce academic procrastination.


2021 ◽  
pp. 135406882110524
Author(s):  
Sergi Ferrer

Which is better for electoral accountability: a fragmented opposition that gives plenty of alternatives or an opposition with fewer stronger parties? While oppositions play a key role in democracies, the effect of opposition fragmentation on accountability remains unclear. On the one hand, fragmentation may enhance accountability by providing voters with ideologically close alternatives. On the other hand, increased fragmentation could make coordination over strong viable alternatives more difficult. In this study, I present an original survey experiment designed to test whether fragmentation of the opposition enhances accountability. Moreover, to assess the specific conditions under which fragmentation may enhance accountability, I distinguish between ideologues and pragmatic voters, and differentiate between ideological and valence issues. Results show that opposition fragmentation enhances accountability, particularly for ideologues. Lastly, I present a direct test of the mechanisms that demonstrates that fragmentation improves accountability because marginal gains in ideological proximity outweigh losses in viability.


2021 ◽  
Author(s):  
Qingbo Hao ◽  
Ke Zhu ◽  
Chundong Wang ◽  
Peng Wang ◽  
Xiuliang Mo ◽  
...  

Abstract The rapid development of Mobile Internet has spa-wned various mobile applications (apps). A large number of apps make it difficult for users to choose apps conveniently, causing the app overload problem. As the most effective tool to solve the problem of app overload, the app recommendation has attracted extensive attention of researchers. Traditional recommendation methods usually use historical data of apps used by users to explore their preferences, and then make an app recommendation list for users. Although the traditional app recommendation methods have achieved certain results, the performance of app recommendation still needs to be improved due to the following two reasons. On the one hand, it is difficult to construct traditional app recommendation models when facing with the sparse user-app interaction data. On the other hand, contextual information has a large impact on users’ app usage preferences, which is often overlooked by traditional app recommendation methods. To overcome the aforementioned problems, we proposed a Context-aware Feature Deep Interaction Learning (CFDIL) method to explore user preferences, and then perform app recommendation by learning potential user-app relationships in different contexts. The novelty of CFDIL is as follows: (1) CFDIL incorporates contextual features into users' preferences modeling by constructing a novel user and app feature portrait. (2) The problem of data sparsity is effectively solved by the use of dense user and app feature portraits, as well as the tensor operations for label sets. (3) CFDIL trains a new deep network structure, which can make accurate app recommendation using the contextual information and attribute information of users and apps. We applied CFDIL on three real datasets and conducted extensive experiments, which showed that CFDIL outperformed the benchmark method.


2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Alice Pietri ◽  
François Colas ◽  
Rodrigo Mogollon ◽  
Jorge Tam ◽  
Dimitri Gutierrez

AbstractDuring the last 4 decades punctual occurrences of extreme ocean temperatures, known as marine heatwaves (MHWs), have been regularly disrupting the coastal ecosystem of the Peru-Chile eastern boundary upwelling system. In fact, this coastal system and biodiversity hot-spot is regularly impacted by El Niño events, whose variability has been related to the longest and most intense MHWs in the world ocean. However the intensively studied El Niños tend to overshadow the MHWs of shorter duration that are significantly more common in the region. Using sea surface temperature data from 1982 to 2019 we investigate the characteristics and evolution of MHWs, distinguishing events by duration. Results show that long duration MHWs (> 100 days) preferentially affect the coastal domain north of 15° S and have decreased in both occurrence and intensity in the last four decades. On the other hand, shorter events, which represent more than 90% of all the observed MHWs, are more common south of 15° S and show an increase in their thermal impact as well as on the number of affected days, particularly those spanning 30–100 days. We also show that long duration MHWs variability in the coastal domain is well correlated with the remote equatorial variability while the onset of short events (< 10 days) generally goes along with a relaxation of the local coastal wind.


2021 ◽  
Vol 9 ◽  
Author(s):  
Serhat Çelikten ◽  

In this work, 21 different raw perlite (RP) -based geopolymer mortars (RPGMs) were manufactured. Blast furnace slag (BFS) was replaced by RP in 7 different proportions with respect to the CaO/SiO2 oxide ratio of RP and BFS mixture in the RPGMs. Sodium hydroxide (NaOH= 5, 10, and 15 M) was used as alkaline medium for geopolymer synthesis in the RPGMs. The ultrasound pulse velocity (Upv), flexural strength (ffs) and compressive strength (fcs), water absorption, acid and sulfate durability of the RPGMs are investigated. The test results revealed that the BFS improved the mechanical properties of RPGMs for the low and medium alkaline medium of 5M and 10M, respectively. On the other hand, BFS had negative effect on the mechanical properties of RPGMs produced at a high alkaline medium of 15M. Moreover, the BFS improved the acid and sulfate durability of the RPGMs.


2021 ◽  
Vol 2 (4) ◽  
pp. 991-1009
Author(s):  
Philippe Besson ◽  
Luise J. Fischer ◽  
Sebastian Schemm ◽  
Michael Sprenger

Abstract. Mechanisms driving the intensification and propagation direction of extratropical cyclones are an active field of research. Dry-dynamic forcing factors have been established as fundamental drivers of the deepening and propagation of extratropical cyclones, but their climatological interplay, geographical distribution, and relatedness to the observed cyclone deepening and propagation direction remain unknown. This study considers two key dry-dynamic forcing factors, the Eady growth rate (EGR) and the upper-level induced quasi-geostrophic lifting (QGω), and relates them to the surface deepening rates and the propagation direction during the cyclones' growth phase. To this aim, a feature-based cyclone tracking is used, and the forcing environment is climatologically analysed based on ERA-Interim data. The interplay is visualized by means of a forcing histogram, which allows one to identify different combinations of EGR and QGω and their combined influence on the cyclone deepening (12 h sea-level pressure change) and propagation direction. The key results of the study are as follows. (i) The geographical locations of four different forcing categories, corresponding to cyclone growth in environments characterized by low QGω and low EGR (Q↓E↓), low QGω but high EGR (Q↓E↑), high QGω and low EGR (Q↑E↓), and high QGω and EGR (Q↑E↑), display distinct hot spots with only mild overlaps. For instance, cyclone growth in a Q↑E↑ forcing environment is found in the entrance regions of the North Pacific and Atlantic storm tracks. Category Q↓E↑ is typically found over continental North America, along the southern tip of Greenland, over parts of East Asia, and over the western North Pacific. In contrast, category Q↑E↓ dominates the subtropics. (ii) The four categories are associated with different stages of the cyclones' growth phase: large EGR forcing typically occurs earlier, during the growth phase at genesis, while large QGω forcing attains its maximum amplitude later towards maturity. (iii) Poleward cyclone propagation is strongest over the North Pacific and North Atlantic, and the poleward propagation tendency becomes more pronounced as the deepening rate gets larger. Zonal, or even equatorward, propagation on the other hand is characteristic for cyclones developing in the lee of mountain ranges, e.g. to the lee of the Rocky Mountains. The exact location of maximum QGω forcing relative to the surface cyclone centre is found to be a good indicator for the direction of propagation, while no information on the propagation direction can be inferred from the EGR. Ultimately, the strength of the poleward propagation and of the deepening is inherently connected to the two dry-dynamic forcing factors, which allow cyclone development in distinct environments to effectively be identified.


2021 ◽  
Vol 118 (44) ◽  
pp. e2110503118
Author(s):  
Bruno Zappone ◽  
Roberto Bartolino

Common fluids cannot sustain static mechanical stresses at the macroscopic scale because they lack molecular order. Conversely, crystalline solids exhibit long-range order and mechanical strength at the macroscopic scale. Combining the properties of fluids and solids, liquid crystal films respond to mechanical confinement by both flowing and generating static forces. The elastic response, however, is very weak for film thicknesses exceeding 10 nm. In this study, the mechanical strength of a fluid film was enhanced by introducing topological defects in a cholesteric liquid crystal, producing unique viscoelastic and optomechanical properties. The cholesteric was confined under strong planar anchoring conditions between two curved surfaces with sphere–sphere contact geometry similar to that of large colloidal particles, creating concentric dislocation loops. During surface retraction, the loops shrank and periodically disappeared at the surface contact point, where the cholesteric helix underwent discontinuous twist transitions, producing weak oscillatory surface forces. On the other hand, new loop nucleation was frustrated by a topological barrier during fluid compression, creating a metastable state. This generated exceptionally large forces with a range exceeding 100 nm as well as extended blueshifts of the photonic bandgap. The metastable cholesteric helix eventually collapsed under a high compressive load, triggering a stick-slip–like cascade of defect nucleation and twist reconstruction events. These findings were explained using a simple theoretical model and suggest a general approach to enhance the mechanical strength of one-dimensional periodic materials, particularly cholesteric colloid mixtures.


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