scholarly journals Magnetohydrodynamic Dissipation

1958 ◽  
Vol 8 ◽  
pp. 975-978
Author(s):  
L. Biermann ◽  
A. Schlüter

Before entering the subject of magnetohydrodynamic dissipation we comment briefly on the question of thesupplyof kinetic energy to the interstellar gas. This topic has been considered in the 1953 Symposium by Schlüter and myself, and also by Oort. As had been pointed out already by Spitzer in Paris, 1949, the visible HII regions, owing to their excess pressure as compared with the HI regions and the dilute HII regions, must be assumed to expand with a velocity of the order of 10 or 20 km/sec. By this expansion part of the radiation energy of the star is converted into kinetic energy. It was estimated (p. 153 of the proceedings) that a typical HII region around a BO star feeds 1035ergs/sec to the instellar gas, and that the number of these regions is such, that each region has to provide kinetic energy on the average to 1036−1037g of interstellar material. Thus a value of 10−2−10−1erg g−1sec−1was found (which corresponds to 10−26−10−25erg cm−3sec−1, assuming 10−24g/cm3for the mean density of the interstellar material in the disk).

1985 ◽  
Vol 106 ◽  
pp. 575-584
Author(s):  
S. R. Pottasch

Abundances in interstellar clouds, as determined from interstellar absorption lines, are discussed first, including abundances in ‘abnormal’ (high-velocity) clouds. HII-region abundances are then discussed and compared to results from the interstellar clouds. The present status of an abundance gradient as determined from HII regions is given. Abundances in planetary nebulae are then given for various categories of nebulae, and compared to HII regions. Finally a short status report on abundances near the galactic center is given.


1998 ◽  
Vol 15 (1) ◽  
pp. 141-143 ◽  
Author(s):  
M. S. Oey ◽  
R. C. Kennicutt

AbstractWe use the stellar census of OB associations in the Large Magellanic Cloud (LMC) to predict the Hα luminosities of the host HII regions, based on results from stellar atmosphere models. These values are compared to the observed HII region luminosities, yielding an estimate for the mean fraction of H-ionising photons that escape the local nebulae in this sample. We formally estimate that, overall, 0–51% of the ionising radiation escapes the local HII regions and is available to ionise the warm, ionised medium in the LMC. We find both nebulae that appear to be density-bounded and ones that appear to be radiation-bounded.


Author(s):  
Putri Denaya Side Ayu ◽  
Heri Hidayatullah ◽  
Sri Ariani

This Collaborative Classroom Action Research aimed at enhancing students’ speaking skill through the application of Circle Game. It was conducted in one cycle consisting of two meetings. The subject was the seventh of C class of SMPN 2 Alas Barat consisting of 22 students. The types of data were qualitative (acquiring observation during the learning process) and quantitative (speaking tests). The results qualitatively showed that the implementation of Circle Game enhanced the students’ speaking skills. Such improvement could be seen from their enthusiasm, their interesting feeling in various materials presented by the teacher, their active involvement. In the quantitative findings, the result also showed a higher value of the mean score of the post-test (77.34) rather than the pre-test (75.75). In conclusion, the use of Circle Game can improve students’ speaking skill.


2015 ◽  
Vol 8 (2) ◽  
pp. 93
Author(s):  
Juniar Siregar

This study presents a research report on improving students’ Learning results on IPA through Video. The objective was to find out whether students’ learning result improved when they are taught by using Video. It was conducted using classroom action research method. The subject of the study was the Grade IV students of SDN 187/IV Kota Jambi which is located on Jln. Adi Sucipto RT 05 Kecamatan Jambi Selatan, and the number of the students were 21 persons. The instruments used were test. In analyzing the data, the mean of the students’ score for the on fisrt sycle was 65,4 (42,85%) and the mean on cycle two was 68,5 (37,15%) and the mean of the third cycle was 81,4 (100%). Then it can be concluded that the use of video on learning IPA can improve the students’ learning result. It is suggested that teachers should use video as one of the media to improve students’ learning result on IPA.Keywords : IPA, students’ learning result, video


1973 ◽  
Vol 72 (2) ◽  
pp. 265-271 ◽  
Author(s):  
J. H. Dussault ◽  
D. A. Fisher ◽  
J. T. Nicoloff ◽  
V. V. Row ◽  
R. Volpe

ABSTRACT In order to determine the effect of alterations in binding capacity of thyroxine binding globulin (TBG) on triiodothyronine (T3) metabolism, studies were conducted in 10 patients with idiopathically low (7 subjects) or elevated (3 subjects) TBG levels and 10 subjects given norethandrolone (7 male subjects) or oestrogen (3 female subjects). Measurements of serum thyroxine (T4) concentration, maximal T4 binding capacity, serum T3 concentration and per cent dialyzable T3 were conducted. Serum T3 was measured both by chemical and radioimmunoassay methods. In patients with idiopathically low TBG, the mean serum T4 concentration was low (2.4 μg/100 ml), the mean serum T3 level low (55 ng/100 ml), the mean per cent dialyzable T3 increased (0.52%), and the calculated free T3 concentration normal (186 pg/100 ml). In patients with idiopathically high TBG levels the mean T4 concentration was high (10.3 μg/100 ml), the mean T3 level slightly elevated (127 ng/100 ml), the% dialyzable T3 low (0.10%) and the calculated free T3 concentration low normal (123 pg/100 ml). The correlation coefficient between the per cent dialyzable T3 and maximal TBG binding capacity in the 20 subjects was 0.68, a value significant at the P < 0.01 level. Thus, alterations in binding capacity of TBG seem to influence T3 and T4 metabolism similarly; the inverse relationship between the % of dialyzable hormone and total hormone concentration tends to keep the absolue levels of free hormones stable.


Author(s):  
Eko Widoyo Putro ◽  
Berlin Sibarani

This study is aimed at improving the second grade of students’ speakingachievement by using Community Language Learning (CLL) Method. Theresearch was conducted by applying classroom action research. The subject of this study was second grade of Private Senior High School (Sekolah Menengah Atas Swasta) of Dwi Tunggal Tanjung Morawa which consisted of 31 students. To collect the data, the instruments used were primary data (SpeakingTest) and secondary data (interview sheet, observation sheet, field notes). It can be seen from the score in test I, test II and test III. In the Test I, the mean of the students’score was (64.77), in the Test II was (71.35), and the mean of the students’ score of the Test III was (80.90). Based on the interview, and observation sheet, it shows that the expression and excitement of the students got improved as well. It was found that teaching of speaking by using Community Language Learningcould significantly improve students’ speaking achievement.Key Words: Community Language Learning, Method, Improvement, Speaking Achievement


Author(s):  
Ruth Adelina Sianturi ◽  
Sumarsih Sumarsih

This study deals with the improving students’ achievement in reading narrative text by using reciprocal teaching. The research of this study was conducted by using action research. The subject of this study was the tenth grade students SMA Negeri 6 Medan. One class was taken as the subject, namely the students from X-5. There were 49 students, consisting of 22 male and 27 female. This research was done in two cycles; there was three meetings in cycle I and three meetings in cycle II. The instruments for collecting data were reading narrative text (25 items of multiple choice tests) teacher make test as quantitative data and interview sheet, observation sheet and diary notes as qualitative data. In analyzing the data, the mean of the students’ score for the treatment I was 61.79, for the treatment II was 72.24 and treatment III was 81.71. The data showed that the students’ score was rising in every treatment. The conclusion is that the use of reciprocal teaching method can improve students’ reading comprehension in narrative text. It suggested to English teacher to apply reciprocal teaching method in teaching reading comprehension. Key words: reading, narrative text, reciprocal teaching.


Author(s):  
Hotria Manik ◽  
Elia Masa Ginting

This study attempts to improve students’ writing achievement in recount text through Think-Pair-Share Strategy. This study was conducted by using classroom action research. The subject of the research was class VIII-1 SMPN 1 Pematangsiantar. The number of the students was 32 students, consisted of 5 males and twenty seven females. The research was conducted in two cycles and consisted of six meetings. The instruments for collecting data were writing tests as the quantitative data and diary notes, observation sheet, interview sheet and questionnaire sheet as qualitative data. Based on the writing score, students’ scores kept improving in every test. In analyzing the data, the mean of the students’ score for the first test as a pre-test was 57.84, for the second test as a post test I was 73.56, for the third test as a post test II was 77.56. Based on diary notes, observation sheet and questionnaire sheet, it was found that students were actively involved in writing process. The result of the research showed that Think-Pair-Share Strategy can improve students’ achievement in writing recount text.   Keywords: Think Pair Share, Writing, Recount text, Action research


Author(s):  
DesiYusnanda Sari And Sri MindaMurni

This study attempted to improve the students’ reading comprehension achievement in descriptive text through Team Games Tournament (TGT) method. This study was conducted by using classroom action research. The subject of the research was class IX SMP PAB 10 Medan Estate which consisted of 25 students. The research was conducted in two cycles and the first cycle consisted of four meetings the second cycle consisted of two meetings. The instruments for collecting the data were quantitative data (reading evaluation) and qualitative data (diary note, observation sheet and interview sheet). Based on reading scores, students’ score kept improving in every evaluation. In the test I the mean was 65,33, in the test II the mean was 71,72 and the test III the mean was 84,54.Based on diary note, observation sheet and interview sheet, it was found that teaching-learning process ran well. Students were active, enthusiastic, and interested in reading. The result of the research showed that Team Games Tournament (TGT) method significantly improved students’ achievement in reading comprehension especially in reading descriptive text.


Author(s):  
Sri Wuri Handayani And Masitowarni Siregar

This study attempts to Improving Students’ Achievement Through the Process GenreApproach. The objective of the study is to discover whether the use of the ProcessGenre approach could significantly improve students’ writing achievement. This studyconduct by applying Classroom Action Research which was carried out in two cycles inten meetings. The subject of this study of SMA Panca Budi Medan which consisted of39 students of class X – 2 reguler.. Orientation test was done in the first meeting, test IIwas done in the fourth meeting, and test III was done in the last meeting. The mean ofstudents’ score test III (76,242) was higher than the test II (66,878) and test I (57,606).Besides, the qualitative data was taken from observation sheet, interview, questionnaire,and diary notes. It was found that teaching learning process ran well. By applying theProcess Genre Approach in the classroom, the students understood the content ofdescriptive text easily. They also were active and enthusiastic during the teachinglearning process. The result of the research showed that the application of the ProcessGenre approach significantly improved students’ achievement in writing descriptive text


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