bluuebunny/crossref_metadata_2025_split huggingface dataset:
Rotation of the curve as far as α with center P(m, n)
Authors: Hasanah S U , Rahmawati S , Pathuddin  
Published: February 2021

Abstract
Mathematics consists of several scientific groups, including the geometry group. Rotation material is one of the sciences that is included in the transformation geometry group and is a deductive science and is still growing and developing, both in terms of theory and in terms of usage. In line with the development of transformation geometry, there have been many ways or approaches that have been successfully compiled by experts. The problems studied in this research are: How is the image of a curve when it is rotated as far as αº with the center P(m, n) and what are the characteristics of the image. This research uses literature review method, which is to conclude and identify theories that can support this research, especially those related to parameter equations, rotation and others. Using the parameter equation, image the curve with the equation f (x,y) = 0 to be rotated as far as αº with the center of P(m, n) is f (x,y) = 0. The relationship between the line and the equation f (x,y) = 0 with its image, if it is rotated as far as with the center of P(m, n), among others: If a straight line is rotated by the center of P(m, n), then its shadow coincides with the original line.
Characteristics of lipid content from the analysis of structural and optical properties of brown seaweed (Sargassum
polycystum) after defatting by petroleum ether: preliminary studies
Authors: Rahmi M H , Metusalach M , Rahim S W , Heryanto  , Tahir D 
Published: February 2021

Abstract
In Indonesia, one species of brown seaweed is Sargassum polycystum, which has not been optimally utilized. Whereas their wide range of potentiality, especially their bioactive compounds. Several authors have reported that the chemical composition of seaweeds varies according to maturity, habitats, environmental conditions, treatment, and species. This work describes the structural and optical properties of Sargassum polycystum after treatment by petroleum ether to remove lipid content. The structural properties determined from the quantitative analysis of XRD spectra. The chemical bond and optical properties determined from the quantitative analysis of FTIR Spectra by applying Kramers-Kronig relation. The data XRD showed an increasing the average of the crystallite size from (23.92 nm Scherrer method; 14.35 nm Williamson-Hall method; 19.23 nm Size strain plot method) to (32.39 nm Scherrer method; 20.07 nm Williamson-Hall method; 28.06 nm method) after treatment. The analysis of FTIR showed COC, CCH, CH, and OH bonding.
The thinking process of the teachers with pseudo contingent when giving scaffolding in the teaching and learning of mathematics
Authors: Anwar  , Yani B , Khairunnisak C , Mailizar  
Published: February 2021

Abstract
This study aims to describe thinking processes of teachers with pseudo contingent when they give scaffolding in the teaching and learning of mathematics. The participants of this study were two teachers who teach mathematics at high schools in Banda Aceh and Aceh Besar. To collect the data, the researchers recorded the teachers’ classroom practices by using videotape. Later on, the researchers interviewed the teachers by using a method namely stimulated recall. Furthermore, the researchers explored the teachers’ thinking processes based on three criteria consisted of generating ideas, clarifying ideas and assessing ideas. Findings showed that the participants only considered learning outcome as a component which has to be mastered by the students rapidly. In other words, the teachers only assisted the students to understand the subject without considering the value of their assistance. Moreover, the participants were not eager to understand the mathematical concepts. Therefore, they had misconceptions about contents of mathematics given and were not able make decisions when they gave the scaffolding to the students.
High school students’ mathematic literacy performance in solving linear programming problem
Authors: Sugiarto Iwan Jadi , Usodo B , Saputro D R S 
Published: February 2021

AbstractThe mathematic literacy performance is the capability that is gotten by students applied on daily activities. The ability which uses logical thinking and knowledge that they got can solve the proses of learning till the subject can be used for life in 21 centuries. This research supposes to describe mathematic ability of student on grade XI IPA 1 SMA N 1 Karangdowo. This type of research is qualitatively descriptive. The research subject of 32 students which are taken using purposive sampling method. The result of research shows that mathematic literacy performance of student only reach on the third level, those are can present the resource information. The first indicator is 87,50% which the highest categorized. The second indicator is 75,78% which the higher categorized. The third indicator is 70,31% which the medium categorized. The fourth indicator is 39,06% which the low categorized. The fifth indicator is 1,56% which the lower categorized and on the sixth indicator is 0%, so that overall can be seen the average mathematic literacy performance for student grade XI IPA 1 is 45,70% with low categorized. The teacher should not push comprehension routine procedural but also variety in giving problem.
Exploration Ethnomathematics on Traditional House Ume Kbubu in North Central Timor Districts
Authors: Tlonaen Maritce Alfrida , Deda Yohanis Ndapa 
Published: February 2021

Abstract
One solution to preserve the culture that exists in each region is to introduce culture to students through the world of education especially mathematics education. It is said so because mathematics has actually been applied by the community in various daily activities. Introducing culture through mathematics learning can be done by observing regional culture, exploring the mathematical concepts contained in the culture and then applying it in class learning. The purpose of this study is to explore the hidden mathematical concepts in the traditional house of Ume Kbubu in North central Timor (TTU) Districts. This research is a qualitative research with ethnographic approach. Data collection techniques through interviews, observation, and documentation. Data analysis techniques were carried out by data reduction, data presentation and conclusion drawing. The results of this study were mathematical concepts contained in the structure of Ume Kbubu buildings in TTU Regency including cones, tubes, circles, squares and similar concepts. From these results it can also be explained to students about points, lines and angles. Through mathematical concepts wich found it can be used to facilitate students to understand the abstract mathematical concepts. In addition, it can also be used as a tool to introduce students to the existing culture.
How are Students’ Conceptual Understanding for Solving Mathematical Problem?
Authors: Kholid Muhammad Noor , Imawati Ayu , Swastika Annisa , Maharani Swasti , Pradana Lingga Nico 
Published: February 2021

Abstract
This study describes students’ conceptual understanding in solving mathematical problems. Conceptual understanding is an important component in learning mathematics. By learning mathematics students are able to apply concepts and think logically. The qualitative research took students of SMP Negeri 1 Gatak Sukoharjo Indonesia. There were 59 students who were tested to find out the conceptual understanding. All students are categorized into 16 students with high mathematical ability (Subject S-1), 25 students with moderate ability (Subject S-2), and 18 students with low mathematical ability (Subject S-3). Data collected through tests, video recordings, field notes, and interviews. Data analysis techniques include data reduction, data presentation, and drawing conclusions. The validity of the data is obtained through validation and triangulation. Subjects with high mathematical ability can solve mathematical problems correctly. Subjects with moderate mathematical abilities are able to solve the given problem but not all indicators on understanding the concept fulfilled. Subjects with low mathematical abilities are not able to solve problems precisely. Research contributes as a new reference to the theory of conceptual understanding.
The effect of using worksheet on students’ number sense ability
Authors: Wulandari Nourma Pramestie , Safitri A S , Novitasari D , Salsabila N H , Suliani M 
Published: February 2021

AbstractNumber Senseis a basic thing to learn mathematics, especially on numbers material. As a matter of fact, the preliminary research showed that students’number senseability was so poor. Therefore, using students’ worksheet as learning media on numbers material are expected to help students to understand the material. It implies, students’number senseability can be better. The aim of this study is to figure out the effect of using worksheet on students’number senseability. This study is using quantitative method with Wilcoxon Test. The number of 37 students were involved as a sample and chosen by random sampling technique. The result showed that the average score = 75.24 after students got the worksheet are higher than before they got the worksheet = 55.04. The result of hypothesis withZscore = -5.314 and p value = 0.000, soHtwas accepted. It means that there was different between before and after using the students’ worksheet. This result also showed that there was the effect of using worksheet on students’number senseability with an average increase of 19,00.
Learning Style Preferences and Students’ Abilityn Mathematical Investigation on Display Data
Authors: Maulina Shofiya , Nisa Lulu Choirun , Nadhifah  
Published: February 2021

Abstract
A mathematical investigation is an inquiry activity to solve a mathematical problem. Good investigative skills will support mathematical problem-solving and mathematical literacy. The purpose of this study is to explore students’ mathematical investigation based on Kolb’s learning styles: diverging, assimilating, converging, and accommodating. Mathematical investigation is measured by four indicators, i.e Specialization, Conjecturing, Justification, and Generalization. This is a qualitative study and the subjects were 7th-grade students of Islamic Secondary School Manahijul Huda Ngagel, Pati, Central Java. The results showed that there are differences students’ ability of mathematical investigastion for accomodator and divergent, also for accomodator and convergent. Students with accommodating learning styles have better investigative abilities, demonstrated on indicators specialization, conjecturing, justification and generalization. Students with assimilation learning styles have a good specialization and generalization but are less successful in the process of conjecture and justification. Conversely, students with convergent learning styles are only good at specialization, but not for conjecturing, justification, and generalization. Students with divergent learning styles have the most difficulty when doing divergent less able to do specialization, conjecture, and generalization.
Visual-spatial intelligence level of junior high school students: what difficulties are experienced by the students
Authors: Triutami Tabita Wahyu , Novitasari D , Tyaningsih R Y , Elvierayani R R , Lu’luilmaknun U 
Published: February 2021

AbstractVisual-spatial intelligence is one important intelligence to solve mathematics problems, especially in geometry. The present research aims to find out junior high school students’ visual-spatial intelligence level and to identify the components of visual-spatial intelligence that are poorly mastered by students. The instrument of this research was a visual-spatial intelligence test. The test consisted of 18 multiple choice questions arranged based on three components of visual-spatial intelligence. The participants were 77 third grade junior high school students in Lombok, Indonesia. The collected data were analysed a using descriptive quantitative method. The findings were 2 students had a high level of visual-spatial intelligence, 65 students had an average level of visual-spatial intelligence, and 10 students had a low level of visual-spatial intelligence. In terms of the ability to accurately perceive the visual world, students were still weak when it comes to counting a particular configuration question. In terms of transforming visual experience, students have difficulty when working on questions about mental rotation. In terms of modifying visual experience, questions about folding and unfolding a particular configuration were poorly mastered by students.
The effect of application of contextual teaching and learning model on mathematical problem solving ability based on self regulated learning of high school students in Pekanbaru
Authors: Zubaidah Amir MZ , Supriyanto Desi Puspitasari , Andriani Lies , Nurdin Erdawati 
Published: February 2021

Abstract
This objective of study was to analyze whether any differences in mathematical problem solving abilities (KPMM) between the students taking Contextual Teaching and Learning (CTL) with students taking Direct Learning (PL), based on students’ Self Regulated Learning (SRL), and finding whether there were any effects of the interaction between the learning model and SRL on KPMM students. This research was a quasi-experimental study involving social science class X students in the odd semester at SMA Negeri 2 Pekanbaru in the academic year 2019/2020. The sample taken was class X IPS 1 and X IPS 2 using purposive sampling. Research data were collected through posttest of mathematical problem solving abilities, students’ SRL questionnaire. Data were analyzed through two-way ANOVA. Based on the findings of data analysis, it were concluded that: 1) There were differences in KPMM between students taking CTL learning with students taking PL; 2) There were differences in KPMM students when analized from the level of SRL; and 3) There was no effect of interaction between learning models with SRL on KPMM students
The decision tree classification with C4.5 and C5.0 algorithm based on R to detect case fatality rate of dengue hemorrhagic fever in Indonesia
Authors: Abdullah Afif Zakiy , Winarno B , Saputro D R S 
Published: February 2021

Abstract
Dengue hemorrhagic fever (DHF) is a deadly disease that is transmitted through mosquito bites from the genus Aedes especially Aedes aegypti, Aedes aegypti can occur every year and affect any age. DHF has a high case fatality rate (CFR). Therefore we need a method that can detect CFR of DHF in Indonesia, one of which is the decision tree classification based on C4.5 and C5.0 algorithm. C4.5 and C5.0 algorithm starting with forming a root node and ending with a leaf node by evaluating attributes using information gain to measure the effect of attributes in classifying a dataset. In this article, an applied research is carried out, namely applying the decision tree classification with C5.0 and C4.5 algorithm based on R software to detect CFR of DHF in Indonesia. The attributes used are the incidence rate (IR), population density, many hospitals, and many medical personnel. The results show that C5.0 algorithm has a big error than the C4.5 algorithm, while the C5.0 algorithm has a smaller tree than the C4.5 algorithm.
A Class of Non-Linear AGARCH(1,1) Model in Modeling Volatility of Returns
Authors: Nugroho Didit Budi 
Published: February 2021

Abstract
There are various forms of GARCH (Generalized Autoregressive Conditional Heteroskedasticity) modeling. The contribution of this study is to propose a class of non-linear AGARCH (Asymmetric GARCH) model by applying the Simple Tukey transformation to the lagged-volatility equation. The model is fitted to the daily returns of buying exchange rate of the USD (US Dollar) to the IDR (Indonesian Rupiah) from January 2010 to December 2017. The Adaptive Random Walk Metropolis (ARWM) method is employed in the Markov chain Monte Carlo algorithm to estimate model parameters. This study finds that both asymmetric effect (between return and volatility) and non-linearity in volatility are statistically significant, suggesting to incorporate both parameters into the GARCH(1,1) model. To choose the better fit model, the Log-likelihood Ratio Test (LRT) and Deviance Information Criterion (DIC) are employed. The empirical results indicate that the proposed model outperforms the basic AGARCH(1,1) model. Therefore, this study suggest a new class of non-linear AGARCH model.
AMAZonn (A Multicollinearity-adjusted Adaptive LASSO for Zero-infated Count Regression) with Weight of Expectation Maximization Standard Error Adaptive LASSO (SEAL AL) for Zero Inflated Poisson Data
Authors: Ismah  , Notodiputro Khairil Anwar , Sartono Bagus 
Published: February 2021

AbstractLasso as selecting predictor variables continue to experience development like an adaptive Lasso which gives weight value in its formula. In a modelling case, variables selecting technique is needed in order to get a stable model, however, multicollinear cases are often found in several cases which caused the models obtained are unstable since the values of variance became large. Besides, data counting on response variable, with the presence of excess zero, causes the linear model cannot be applied, hence, using generalized linier modelling with zero inflated poisson (ZIP) model can become the solution. Thus, in this research, ZIP model will be applied after selecting the variables through AMAZoon (A Multicollinearity-adjusted Adaptive LASSO for Zero-infated Count Regression) with Weight ofExpectation Maximization Standard Error Adaptive LASSO(SEAL AL), and the comparison towards the results gained by ZIP model without prior variables selection will be done. The comparison was seen based on the value of the smallestAkaike Information Criterion(AIC). The data analysis revealed that there was multicollinear case in the data, and also ZIP model, after conducting the variables selection by using AMAZoon with Weigth SEAL AL, reached smaller AIC than ZIP model which having no variable selection. Therefore, ZIP model after the selection of variables by using AMAZoon with Weight of SEAL AL was better to be used when multicollinear happened.
Microstructure and nanomechanical properties of the exoskeleton of an ironclad beetle (Zopherus haldemani)
Authors: Lee Nayeon , Berthelson Parker R , Nguyen Vina , Garrett Me'Lanae , Brinda AnneMarie K , Moser Robert D , Horstemeyer M F , Rhee Hongjoo , Prabhu R K 
Published: February 2021

Abstract
This study examined natural composite structures within the remarkably strong exoskeleton of the southwestern ironclad beetle (Z. haldemani). Structural and nanomechanical analyses revealed that the exoskeleton’s extraordinary resistance to external forces is provided by its exceptional thickness and multi-layered structure, in which each layer performed a distinct function. In detail, the epicuticle, the outmost layer, comprised 3%–5% of the overall thickness with reduced Young’s moduli of 2.2–3.2 GPa, in which polygonal-shaped walls (2–3 μm in diameter) were observed on the surface. The next layer, the exocuticle, consisted of 17%–20% of the total thickness and exhibited the greatest Young’s moduli (∼15 GPa) and hardness (∼800 MPa) values. As such, this layer provided the bulk of the mechanical strength for the exoskeleton. While the endocuticle spanned 70%–75% of the total thickness, it contained lower moduli (∼8–10 GPa) and hardness (∼400 MPa) values than the exocuticle. Instead, this layer may provide flexibility through its specifically organized chitin fiber layers, known as Bouligand structures. Nanoindentation testing further reiterated that the various fibrous layer orientations resulted in different elastic moduli throughout the endocuticle’s cross-section. Additionally, this exoskeleton prevented delamination within the composite materials by overlapping approximately 5%–19% of each fibrous stack with neighboring layers. Finally, the innermost layer, the epidermis contributing 5%–7 % of the total thickness, contains attachment sites for muscle and soft tissue that connect the exoskeleton to the beetle. As such, it is the softest region with reduced Young’s modulus of ∼2–3 GPa and hardness values of ∼290 MPa. These findings can be applied to the development of innovative, fiber-reinforced composite materials.
Application of spectra pre-treatments on firmness assessment of intact sapodilla using vis-nir spectroscopy
Authors: Kusumiyati  , Mubarok S , Sutari W , Hadiwijaya Y 
Published: February 2021

Abstract
This study aimed to obtain the best calibration model from various spectra pre-treatment methods to assess sapodilla fruit firmness using vis-nir spectroscopy. Before the spectra data measurement, samples were treated with storage of 0, 5 and 10 days at room temperature. Spectra data measurement was carried out using the NirVana AG410 visible and near infrared spectrometer from 312 to 1050 nm with interval of 3 nm. RAW spectra were pre-treated using the multiplicative scatter correction (MSC), standard normal variate (SNV), and Savitzky-Golay first derivative (dg1) with 9 points of smoothing. The calibration model was developed using PLS (partial least squares) method. Validation was done by K fold cross validation method. The results showed the MSC and SNV spectra were able to eliminate noises of RAW spectra, whereas in the dg1 spectra, noises were still visible. The best model was acquired by SNV spectra with R2 (coefficient of determination) of calibration and validation of 0.882 and 0.870, root mean square error of calibration (RMSEC) and root mean square error of cross validation (RMSECV) values of 2.92 and 3.08, and the ratio of performance to deviation (RPD) of 2.76. The result indicated the spectra pre-treatments were able to improve the accuracy of calibration model on assessment of sapodilla fruit firmness.
Rapid detection of patchouli oil mixed by coconut oil using NIRS technology and chemometrics method
Authors: Zulfahrizal  , Muhammad Syaifullah , Munawar Agus Arip , Mahlinda  
Published: February 2021

Abstract
Aceh patchouli oil is sometimes mixed with various oils for profit resulting in the low quality of patchouli oil. This low quality caused Aceh patchouli oil to depress its selling price. The main objective of this study is to develop NIRS technology to investigate the authenticity of patchouli oil mixed with coconut oil using Principal Component Analysis (PCA) and Linear Discriminant Analysis (LDA) methods. This present study uses 6 kinds of sample treatment namely pure oil and mixed oil with a total of 42 samples for calibration and 18 samples for validation. The results showed that NIRS Technology with PCA and LDA methods provides a solution opportunity to solve the problem of counterfeiting patchouli oil with coconut oil. The PCA method successfully obtained a classification model that was able to provide a clear visual appearance to distinguish between pure patchouli oil and a mixture of patchouli oil and coconut oil. Meanwhile, the LDA method successfully obtained a validated classification model with the number of errors 1 out of 18 independent validation samples to distinguish between pure patchouli oil and non-patchouli oil.