State University of Medan

This study explores the perceptions of primary school teachers of online learning in a program developed in Indonesia called School from Home during the COVID-19 Pandemic. Data were collected through surveys and semi-structured interviews with 67 class teachers in primary schools. Data analysis used thematic analysis of qualitative data. The analysis results found four main themes, namely, instructional strategies, challenges, support, and motivation of teachers. This research contributes to the literature of online collaborative learning between teachers, parents, and schools that impact student success. Broadly, the success of online learning in Indonesia during the COVID-19 Pandemic was determined by the readiness of technology in line with the national humanist curriculum, support and collaboration from all stakeholders, including government, schools, teachers, parents and the community.

Studies reporting blood levels of the omega-3 polyunsaturated fatty acids, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), were systematically identified in order to create a global map identifying countries and regions with different blood levels. Included studies were those of healthy adults, published in 1980 or later. A total of 298 studies met all inclusion criteria. Studies reported fatty acids in various blood fractions including plasma total lipids (33%), plasma phospholipid (32%), erythrocytes (32%) and whole blood (3.0%). Fatty acid data from each blood fraction were converted to relative weight percentages (wt.%) and then assigned to one of four discrete ranges (high, moderate, low, very low) corresponding to wt.% EPA+DHA in erythrocyte equivalents. Regions with high EPA+DHA blood levels (>8%) included the Sea of Japan, Scandinavia, and areas with indigenous populations or populations not fully adapted to Westernized food habits. Very low blood levels (≤4%) were observed in North America, Central and South America, Europe, the Middle East, Southeast Asia, and Africa. The present review reveals considerable variability in blood levels of EPA+DHA and the very low to low range of blood EPA+DHA for most of the world may increase global risk for chronic disease.

This study aims to analyze the effectivity of interactive multimedia with the theocentric approach on the analytical thinking skills of elementary school students in science learning. This study used a quantitative approach with a quasi-experimental type. The sampling technique used cluster random sampling with 67 students. The data were collected through analytical thinking skills tests given before and after science learning. The data analysis technique used descriptive and inferential statistics analysis by comparing the increase in the average results of the test and t-test. The research results show that the increase of the average value of students' analytical thinking skills in the experimental class is higher, which is an increase of 44.74% compared to the control class which only increases by 17.20%. The results of the t-test also show that there is a significant effect between interactive multimedia with theocentric approach on students' analytical thinking skills with a significance value of 0.00 (<0.05). Therefore, interactive multimedia with the theocentric approach is effectively used to improve the analytical thinking skills of elementary school students in science learning.

Biodiesel is one of the potential alternative energy sources that can be derived from renewable and low-grade origin through different processes. One of the processes is alcoholysis or transesterification in the presence of a suitable catalyst. The catalyst can be either homogeneous or heterogeneous. This article reviews various catalysts used for biodiesel production to date, presents the state of the art of types of catalysts and compares their suitability and associated challenges in the transesterification process. Biodiesel production using homogeneous and heterogeneous catalysis has been studied extensively and novel heterogeneous catalysts are being continuously investigated. Homogeneous catalysts are generally efficient in converting biodiesel with low free fatty acid (FFA) and water containing single-origin feedstock. Heterogeneous catalysts, on the other hand, provide superior activity, range of selectivity, good FFA and water adaptability. The quantity and strengths of active acid or basic sites control these properties. Some of the heterogeneous catalysts such as zirconia and zeolite-based catalysts can be used as both basic and acidic catalyst by suitable alteration. Heterogeneous catalysts from waste and biocatalysts play an essential role in attaining a sustainable alternative to traditional homogeneous catalysts for biodiesel production. Recently, high catalytic efficiency at mild operating conditions has drawn attention to nanocatalysts. This review evaluates the state of the art and perspectives for catalytic biodiesel production and assesses the critical operational variables that influence biodiesel production along with the technological solutions for sustainable implementation of the process.

Qualified learning materials is needed in the efforts to improve the quality of teaching-learning mathematics. Qualified learning materials can be obtained through development research. Learning materials in this study were learning materials that were developed based on guided discovery learning model. The learning materials was also developed by integrating local culture into a guided learning model. The local culture in this study was adapted to the local culture of the students, namely the Batak Toba. Learning materials in this study were developed using the development model of Thiagarajan et al. (1974). The result of second trial showed that learning materials based guided discovery learning with Batak Toba context improved students’ mathematical problem solving ability and self-efficacy significantly. Based on the results of the study, it was suggested that mathematics teachers make an effort qualified learning materials and integrate local culture in mathematics learning.

Solar energy is a renewable energy source that can be utilized for different applications in today’s world. The effective use of solar energy requires a storage medium that can facilitate the storage of excess energy, and then supply this stored energy when it is needed. An effective method of storing thermal energy from solar is through the use of phase change materials (PCMs). PCMs are isothermal in nature, and thus offer higher density energy storage and the ability to operate in a variable range of temperature conditions. This article provides a comprehensive review of the application of PCMs for solar energy use and storage such as for solar power generation, water heating systems, solar cookers, and solar dryers. This paper will benefit the researcher in conducting further research on solar power generation, water heating system, solar cookers, and solar dryers using PCMs for commercial development.

imaging, whose clinical impact is still actively explored by a large number of researchers worldwide.

Despite scientific consensus regarding the importance of the world's forests, the destruction of ecosystems and globally important biodiversity in some parts of the world increases without a concerted plan of action to stop the loss. [ Jepson et al .][1] describe their recent experiences in protected areas and forest concessions of the Sumatra and Kalimantan regions of Indonesia. Illegal logging networks are seizing control of Indonesia's forests; timber plunder followed by forest clearance is rampant. The authors argue for a multiple approach adapted to local contexts, and briefly discuss some possible options. [1]: http://www.sciencemag.org/cgi/content/full/292/5518/859

This study aims to analyze the effectiveness of learning materials oriented on problem-based learning models, the improvement mathematical problem solving ability and students’ metacognition ability. Learning materials that developed are lesson plan, student book, student worksheet, mathematical problem solving ability and students’ metacognition ability test. This research is a development research by using the development model of Thiagarajan, Semmel and Semmel (1974). Valid learning materials according to experts, tested in class VII of SMP Negeri 13 Medan (seventh year junior high school). The results showed that learning materials oriented on problem-based learning met the effective criteria and improved mathematical problem solving and metacognition ability. Level students’ metacognition when problem solving met level of strategic use, aware use, and tacit use.

In patients with epilepsy, treatment with valproate (VPA) has been reported to be associated with polycystic ovary syndrome-like symptoms including weight gain, hyperandrogenemia, and hyperinsulinemia. We examined the effect of VPA on androgen biosynthesis in ovarian theca cells isolated from follicles of normal cycling women to determine whether the hyperandrogenemia reported with VPA treatment could be a result of direct effects of VPA on the ovary. In long-term cultures of theca cells treated for 72 h with sodium valproate (30-3000 microm), we observed an increase in basal and forskolin-stimulated dehydroepiandrosterone (DHEA), androstenedione, and 17alpha-hydroxyprogesterone production compared with control values. In contrast, low doses of VPA treatment (i.e. 30-300 microm) had no effect on basal and forskolin-stimulated progesterone production, whereas higher doses of VPA (1000-3000 microm) inhibited progesterone production. The most pronounced effect of VPA on androgen biosynthesis was observed in the dose range of 300-3000 microm, which represent therapeutic levels in the treatment of epilepsy and bipolar disorder. Western analyses demonstrated that VPA treatment increased both basal and forskolin-stimulated P450c17 and P450scc protein levels, whereas the amount of steroidogenic acute regulatory protein was unaffected. In transient transfection studies, VPA was found to increase P450 17alpha-hydroxylase and P450 cholesterol side-chain cleavage promoter activity, whereas steroidogenic acute regulatory protein promoter activity was unaffected. Consistent with the ability of VPA to act as a histone deacetylase (HDAC) inhibitor in other cell systems, VPA (500 microm) treatment was observed to increase histone H3 acetylation and P450 17alpha-hydroxylase mRNA accumulation. The HDAC inhibitor butyric acid (500 microm) similarly increased histone H3 acetylation and DHEA biosynthesis, whereas the VPA derivative valpromide (500 microm), which lacks HDAC inhibitory activity, had no effect on histone acetylation or DHEA biosynthesis. These data suggest that VPA-induced ovarian androgen biosynthesis results from changes in chromatin modifications (histone acetylation) that augment transcription of steroidogenic genes. These studies provide the first biochemical evidence to support a role for VPA in the genesis of polycystic ovary syndrome-like symptoms, and establish a direct link between VPA treatment and increased ovarian androgen biosynthesis.

The development of good learning resources on inquiry learning model with science literacy as a strategy to facilitate active learning has become a trend in education. Critical thinking ability is needed as a strategy to build students competencies in problem solving and discovery as required in science learning. This study aims to develop a set of learning material on inquiry-based learning with science literacy for the teaching of Chemical kinetics that can improve students' critical thinking skills and students' achievement. The study is conducted through the development of inquiry learning models with science literacy, standardization, and implementation of the learning model as a teaching resource in the class. The study was carried out with involvement of 93 students in the Department of Chemistry, Universitas Negeri Medan. Research data was presented as students' learning outcomes, those are obtained from assessments of critical thinking skill by using assessment sheets, and students' achievement from marks of submitted reports and evaluation test. The results showed that a standard inquiry learning model with science literacy has been developed for Chemical kinetics topic, where the feasibility is categorized to be very good (M = 3.600.06). Implementation of the developed learning model in the teaching and learning activities has proven to be able to improve students' critical thinking skills. Students' thinking abilities are classified as very good, where the achievements are obtained in the range of 72-97%.

The purposes of this study are: (1) to know if students’ mathematical problem-solving ability taught by contextual learning model is higher than students taught by expository learning, (2) to know if students’ self-confidence taught by contextual learning model is higher than students taught by expository learning, (3) to know if there is interaction between learning model and students’ early mathematical ability to improve students' mathematical problem-solving ability, (4) to know if there is interaction between learning model and students’ early mathematical to improve students' self-confidence. This study is a quasi-experimental research. The population in this study consists of 180 students in grade VIII SMP Muhammadiyah 11 Pangkalan Brandan. Two classes (60 students) are taken as sample. Data were analyzed by two way Anova. The results of this study indicate that (1) students’ capability of solving mathematical problems taught with contextual learning model is higher than students taught by expository, (2) students’ self-confidence taught by contextual learning model is higher than students taught by expository, (3) there is interaction between learning model and students’ early mathematical ability to improve students' mathematical problem-solving ability, (4) there is interaction between learning model and students’ early mathematical to improve students' self-confidence. Keywords : Contextual Learning Model, Mathematical Problem-Solving, Self-Confidence  DOI : http://dx.doi.org/10.22342/jme.8.1.3324.85-94

Kurikulum 2013 menuntut agar dalam pelaksanaan pembelajaran siswa diberi kebebasan berpikir memahami masalah, membangun strategi penyelesaian masalah, mengajukan ide-ide secara bebas dan terbuka. Kegiatan guru dalam pembelajaran adalah melatih dan membimbing siswa berpikir kritis dan kreatif dalam menyelesaikan masalah. Guru harus berupaya untuk mengorganisasikan kerjasama dalam kelompok belajar, melatih siswa berkomunikasi menggunakan grafik, diagram, skema, dan variabel. Diharapkan seluruh hasil kerja selalu dipresentasikan di depan kelas untuk menemukan berbagai konsep, hasil penyelesaian masalah, aturan serta prinsip yang ditemukan melalui proses pembelajaran. Pembelajaran tidak hanya ditekankan pada satu aspek saja tetapi keseimbangan pada aspek afektif, aspek psikomotorik, dan aspek kognitif. Kata Kunci : kurikulum 2013 , guru , siswa , afektif , psikomotorik , kognitif

The research is aimed to describe; (1) the development procedure of Actuarial Mathematics learning material with ADDIE model; (2) Validation of learning material using the ADDIE model for Actuarial Mathematics. The research method used is research and development using ADDIE Models. The instrument were used observation and quesionare. The data were analyzed by descriptive qualitative and descriptive quantitative. The results showed that (1) the process of designing and development of the material teachings has followed the five steps in ADDIE model such as analyze, design, development, implementation, and evaluation. (2) The result of the content expert's validation was falling into agreement category, that of the instructional design expert's validation was agreement, that of the instructional media expert was agreement. There were some comment that given by expert about module. The average of student's quesionare were falling into good category.

BACKGROUND AND PURPOSE: While MR findings in progressive multifocal leukoencephalopathy (PML) have been described previously, usually in retrospective studies with limited sample size, what has not been well addressed is whether any are predictive of longer survival. Our participation in a large prospective clinical trial of AIDS patients with biopsy-proved PML and MR correlation allowed us to test our hypothesis that certain MR features could be found favorable to patient survival. METHODS: The patient cohort derived from a randomized multicenter clinical trial of cytosine arabinoside for PML. Pretreatment T1- and T2-weighted noncontrast images (n = 48) and T1-weighted contrast-enhanced images (n = 45) of 48 HIV-positive patients with a PML tissue diagnosis as well as the follow-up images in 15 patients were reviewed to determine signal abnormalities, lesion location and size, and the presence or absence of mass effect, contrast enhancement, and atrophy, and to ascertain the frequency of these findings. A statistical analysis was performed to determine if any MR abnormalities, either at baseline or at follow-up, were predictive of patient survival. RESULTS: No MR abnormalities either on univariate or multivariate analysis significantly correlated with patient survival, with the exception of mass effect, which was significantly associated with shorter survival. The mass effect, however, always minimal, was infrequent (five of 48). More severe degrees of cortical atrophy and ventricular dilatation, lesion location and size, and other MR variables were not predictive of outcome. CONCLUSION: Except for mass effect, we found no MR findings predictive of the risk of death in patients with PML. The mass effect, however, was so infrequent and minimal that it was not a useful MR prognostic sign.

Abstract Learning Management System (LMS) is an application software that used to help in the online learning process. Moodle is one of the most popular LMS applications and is very appropriate for online learning study. Moodle has various features that are able to support student activities online. Some learning activities supported by moodle are (1) Videos; (2) Discussion forums; (3) Chat; (4) Materials; and (5) Quiz. This research is a quasi-experiment research that is research conducted to see the effect a treatment of the sample in this research is students. The aims of this research is to look at student learning activities that are learned in online using by LMS based Moodle applications.

This paper is the result of first phase of the research about the development of students’ mathematical understanding and representation ability through Joyful Problem-based Learning (JPBL) at Public Junior High School in North Sumatera, Indonesia. The population is all of the students of public junior high school (PJHS) in North Sumatera. Samples choose based on stratified random sampling. The samples are the students of PJHS 27 Medan, PJHS 1 Percut Sei Tuan, PJHS 1 Tebing Tinggi, and PJHS 2 Pematangsiantar. The techniques used for collecting data is observation, interview, and essay test. The research findings: (1) Based on interview and observation found that conventional approach still use in all of the class of PJHS; The students engagement in learning activity is very low as well as students self-regulated learning; Most of the students do not attain minimal mastery achievement, (2) Based on essay test found that achievement of the students in mathematical understanding and representation test is categories low. Keywords: mathematical understanding, mathematical representation, joyful problem-based learning  DOI : http://dx.doi.org/10.22342/jme.7.1.2816.43-56

The anesthetic-sparing and hemodynamic effects of the stereoisomers of the highly selective alpha 2-adrenergic agonist medetomidine were studied in halothane-anesthetized dogs. Male beagles were anesthetized with halothane in oxygen. After a 2-hour equilibration period, halothane MAC and baseline hemodynamic functions were determined. DL-(n = 7), D- (n = 5), or L-medetomidine (n = 5) at 1, 3, and 10 micrograms/kg was administered via a right atrial port over 15 minutes while each dog was given halothane at the MAC dose for that animal. Twenty minutes after the end of infusion (when the hemodynamic variables were stable), hemodynamic function was reassessed. Halothane MAC was then redetermined. MAC for halothane significantly decreased after DL-medetomidine administration in a dose-dependent fashion to the extent that at the highest dose (10 micrograms/kg) the halothane MAC was less than 0.1%. This effect could be mimicked by the D-isomer, whereas the L-isomer was without effect. Neither isomer changed the mean arterial pressure, whereas only the D-isomer significantly decreased heart rate and cardiac output. Medetomidine, the highly selective alpha 2-adrenergic agonist, reduces the MAC for volatile anesthesia by a greater degree than with any other physiologic, pharmacologic, or pathologic intervention thus far reported. The fact that this effect is stereospecific suggests a structure activity relation that can be accounted for by a homogeneous receptor population. The role of medetomidine as a supplemental anesthetic agent appears promising and requires further investigation.

This study is aimed to investigate the effectiveness of problem-based learning combined with simulation on students' problem-solving and creative thinking skills. By employing a quasi-experimental design, this study used essay and problem-based tests as the instruments to evaluate problem-solving and creative thinking skills of 192 students. These students were categorized into three groups: experimental group I (n = 68) receiving instruction using problem-based learning combined with simulation, experimental group II (n = 60) receiving instruction with problem-based learning only, and control group (n = 64) receiving instruction with a conventional method. Using a multivariate analysis of covariance, the results revealed that problem-solving and creative thinking skills taught by problem-based learning combined with simulation were significantly improved as compared to those in experimental group II and control group. In addition, a positive relationship was identified between students' problem-solving skills and their creative thinking skills. Ultimately, this study shows that instruction using problem-based learning combined with simulation method is much more effective than using either problem-based learning only or a conventional teaching method.

The purpose of this study is to develop learning materials based on realistic mathematics education approach that are valid, practical and effective to improve problem solving skills and learning independence of class VII students. This research is a development research that uses a design model for materials development according to Thiagarajan, et al. namely 4-D. This trial was carried out in classes VII-3 and VII-4 Padangsidimpuan 5 Middle School. From the results of the study, it was found that developed devices were valid with an average total validity of RPP = 4.46, student books = 4.41, teacher’s books = 4.38, LAS = 4.31; then a practical device can be implemented, with an average of 85% and 91.25%. and effective devices, in terms of a) classical learning completeness of students in 62% I test increased in trial II has reached 92%; and b) student responses to the components of positive learning. Based on the results of the study it was suggested that mathematics teachers can facilitate mathematical learning using quality learning materials and especially by using learning based realistic mathematics education approach.