213 research outputs found

    IC 10: More evidence that it is a blue compact dwarf

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    We present optical spectroscopy of H {\sc ii} regions in the Local Group galaxy IC 10 and UBVRUBVR photometry of foreground stars in three fields towards this galaxy. From these data, we find that the foreground reddening due to the Milky Way is E(BV)=0.77±0.07magE(B-V)=0.77\pm 0.07 \mathrm{mag}. We find that IC 10 contains considerable internal dust, which qualitatively explains the variety of reddening values found by studies of its different stellar populations. Based upon our foreground reddening, IC 10 has intrinsic photometric properties like those of a blue compact dwarf galaxy, and not those of a dwarf irregular. This result is consistent with much evidence that IC 10 is in the throes of a starburst that began at least 10Myr10 \mathrm{Myr} ago. We also report the discovery of a new WR star in the H {\sc ii} region HL111c

    PENGGUNAAN MODEL PEMBELAJARAN AKTIF TEAM QUIZ DALAM MENINGKATKAN KEMAMPUAN MEMBACA PEMAHAMAN BAHASA JEPANG

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    Penelitian ini mengambil judul “penggunaan model pembelajaran aktif team quiz dalam meningkatkan kemampuan membaca pemahaman bahasa Jepang” . membaca pemahaman adalah memahami suatu informasi dari sebuah tulisan. membaca pemahaman merupakan salah satu pembelajaran yang sulit. Disebabkan karena metode yang digunakan oleh pengajar monoton dan kurang memotivasi siswa dalam pembelajaran membaca pemahaman. Penelitian ini bertujuan untuk mengetahui bagaimana penggunaan model pembelajaran aktif team quiz dalam meningkatkan kemampuan membaca pemahaman bahasa Jepang. Penelitian ini menggunakan metode quasi eksperiment dengan one group before-after (pretest dan posttest) design. Sampel dalam penelitian ini adalah siswa kelas XI Bahasa SMA Negeri 1 Parongpong tahun ajaran 2015/2016. Instrument penelitiannya adalah tes dan angket. Berdasarkan analisis data dengan perhitungan statistic yang menggunakan t hitung diketahui bahwa t hitung > t tabel maka Ho ditolak dan Hk diterima yang dapat disimpulkan bahwa penggunaan model pembelajaran aktif team quiz dalam meningkatkan kemampuan membaca pemahaman bahasa jepang efektif. Sedangkan hasil analisis data angket diketahui bahwa penggunaan model pembelajaran aktif team quiz dalam meningkatkan kemampuan membaca pemahaman bahasa Jepang mendapat respon positif dari siswa. ; Reading comprehension is the act of understanding information from a presented text. It is one of difficulties found in learning. It caused by monotonous method conducted by teacher and in turn, students have less motivation on learning reading comprehension. This research aims for how the Team Quiz active learning method can improve reading comprehension in Japanese. The quasi-experiment method with “one group before-after (pretest and posttest)” design is conducted in this research, by taking XI language students from 2015/2016 academic year of SMA Negeri 1 Parongpong as sample. Test and questionnaire is instrument used in this research. According to data analysis with statistical calculation using t count, noting that t count > t table, therefore Ho is rejected and Hk is accepted. To conclude, Team Quiz active learning method is effective in improving reading comprehension in Japanese. Moreover, according to data analysis conducted in questionnaire, the Team Quiz active learning method gains positive responses from students

    Gravitational stability and dynamical overheating of stellar disks of galaxies

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    We use the marginal stability condition for galactic disks and the stellar velocity dispersion data published by different authors to place upper limits on the disk local surface density at two radial scalelengths R=2hR=2h. Extrapolating these estimates, we constrain the total mass of the disks and compare these estimates to those based on the photometry and color of stellar populations. The comparison reveals that the stellar disks of most of spiral galaxies in our sample cannot be substantially overheated and are therefore unlikely to have experienced a significant merging event in their history. The same conclusion applies to some, but not all of the S0 galaxies we consider. However, a substantial part of the early type galaxies do show the stellar velocity dispersion well in excess of the gravitational stability threshold suggesting a major merger event in the past. We find dynamically overheated disks among both seemingly isolated galaxies and those forming pairs. The ratio of the marginal stability disk mass estimate to the total galaxy mass within four radial scalelengths remains within a range of 0.4---0.8. We see no evidence for a noticeable running of this ratio with either the morphological type or color index.Comment: 25 pages, 5 figures, accepted to Astronomy Letter

    The Gas Content in Galactic Disks: Correlation with Kinematics

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    We consider the relationship between the total HI mass in late-type galaxies and the kinematic properties of their disks. The mass MHIM_HI for galaxies with a wide variety of properties, from dwarf dIrr galaxies with active star formation to giant low-brightness galaxies, is shown to correlate with the product VcR0V_c R_0 (VcV_c is the rotational velocity, and R0R_0 is the radial photometric disks scale length), which characterizes the specific angular momentum of the disk. This relationship, along with the anticorrelation between the relative mass of HI in a galaxy and VcV_c, can be explained in terms of the previously made assumption that the gas density in the disks of most galaxies is maintained at a level close to the threshold (marginal) stability of a gaseous layer to local gravitational perturbations. In this case, the regulation mechanism of the star formation rate associated with the growth of local gravitational instability in the gaseous layer must play a crucial role in the evolution of the gas content in the galactic disk.Comment: revised version to appear in Astronomy Letters, 8 pages, 5 EPS figure

    Genotypes and haplotypes in the insulin-like growth factors, their receptors and binding proteins in relation to plasma metabolic levels and mammographic density

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    <p>Abstract</p> <p>Background</p> <p>Increased mammographic density is one of the strongest independent risk factors for breast cancer. It is believed that one third of breast cancers are derived from breasts with more than 50% density. Mammographic density is affected by age, BMI, parity, and genetic predisposition. It is also greatly influenced by hormonal and growth factor changes in a woman's life cycle, spanning from puberty through adult to menopause. Genetic variations in genes coding for hormones and growth factors involved in development of the breast are therefore of great interest. The associations between genetic polymorphisms in genes from the IGF pathway on mammographic density and circulating levels of IGF1, its binding protein IGFBP3, and their ratio in postmenopausal women are reported here.</p> <p>Methods</p> <p>Samples from 964 postmenopausal Norwegian women aged 55-71 years were collected as a part of the Tromsø Mammography and Breast Cancer Study. All samples were genotyped for 25 SNPs in IGF1, IGF2, IGF1R, IGF2R, IGFALS and IGFBP3 using Taqman (ABI). The main statistical analyses were conducted with the PROC HAPLOTYPE procedure within SAS/GENETICS™ (SAS 9.1.3).</p> <p>Results</p> <p>The haplotype analysis revealed six haploblocks within the studied genes. Of those, four had significant associations with circulating levels of IGF1 or IGFBP3 and/or mammographic density. One haplotype variant in the IGF1 gene was found to be associated with mammographic density. Within the IGF2 gene one haplotype variant was associated with levels of both IGF1 and IGFBP3. Two haplotype variants in the IGF2R were associated with the level of IGF1. Both variants of the IGFBP3 haplotype were associated with the IGFBP3 level and indicate regulation in cis.</p> <p>Conclusion</p> <p>Polymorphisms within the IGF1 gene and related genes were associated with plasma levels of IGF1, IGFBP3 and mammographic density in this study of postmenopausal women.</p

    Different measures of smoking exposure and mammographic density in postmenopausal Norwegian women: a cross-sectional study

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    Background: Recent cohort studies have suggested an increased risk of breast cancer with long duration of smoking, and with smoking initiation before first birth. Cigarette smoking may have both carcinogenic effects and antiestrogenic effects on the breast tissue. We decided to examine the relationship between different measures of smoking exposure and mammographic density. Methods: Lifetime smoking history was collected through interview and questionnaires among 907 postmenopausal participants in the Tromsø Mammography and Breast Cancer study. The mammograms were obtained from the governmental Norwegian Breast Cancer Screening Program. Mammograms were classified according to the percentage and absolute mammographic densities using a previously validated computerassisted method. Results:Sixty-five percent of the women reported having ever smoked cigarettes, while 34% were current smokers. After adjustment for age, age at first birth, parity, age at menopause, postmenopausal hormone therapy use, and body mass index, smoking was inversely associated with both measures of mammographic density (both trends P < 0.01). Both current smokers and former smokers had significantly lower adjusted mean percentage mammographic density compared with never smokers (P = 0.003 and P = 0.006, respectively). An inverse dose–response relationship with mammographic density was found between both the number of cigarettes and the number of pack-years smoked among current smokers. Current smokers who smoked 11 cigarettes or more daily had a 3.7% absolute (36% relative difference) lower percentage mammographic density compared with current smokers who smoked seven cigarettes or less daily (P = 0.008). When former smokers were stratified according to time since smoking cessation, we found that women who had stopped smoking less than 24 years ago had a significantly lower mean percentage mammographic density compared with never smokers (P < 0.001). Conclusion: We found modest inverse dose–response associations between numbers of cigarettes and of pack-years smoked and both measures of mammographic density among current smokers. Former smokers who had stopped smoking less than 24 years ago also had a statistically significantly lower mean percentage mammographic density when compared with never smokers. These findings are consistent with an antiestrogenic effect of cigarette smoking on the breast tissue

    Sex steroids, growth factors and mammographic density: a cross-sectional study of UK postmenopausal Caucasian and Afro-Caribbean women

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    INTRODUCTION: Sex steroids, insulin-like growth factors (IGFs) and prolactin are breast cancer risk factors but whether their effects are mediated through mammographic density, one of the strongest risk factors for breast cancer, is unknown. If such a hormonal basis of mammographic density exists, hormones may underlie ethnic differences in both mammographic density and breast cancer incidence rates. METHODS: In a cross-sectional study of 270 postmenopausal Caucasian and Afro-Caribbean women attending a population-based breast screening service in London, UK, we investigated whether plasma biomarkers (oestradiol, oestrone, sex hormone binding globulin (SHBG), testosterone, prolactin, leptin, IGF-I, IGF-II and IGF binding protein 3 (IGFBP3)) were related to and explained ethnic differences in mammographic percent density, dense area and nondense area, measured in Cumulus using the threshold method. RESULTS: Mean levels of oestrogens, leptin and IGF-I:IGFBP3 were higher whereas SHBG and IGF-II:IGFBP3 were lower in Afro-Caribbean women compared with Caucasian women after adjustment for higher mean body mass index (BMI) in the former group (by 3.2 kg/m(2) (95% confidence interval (CI): 1.8, 4.5)). Age-adjusted percent density was lower in Afro-Caribbean compared with Caucasian women by 5.4% (absolute difference), but was attenuated to 2.5% (95% CI: -0.2, 5.1) upon BMI adjustment. Despite ethnic differences in biomarkers and in percent density, strong ethnic-age-adjusted inverse associations of oestradiol, leptin and testosterone with percent density were completely attenuated upon adjustment for BMI. There were no associations of IGF-I, IGF-II or IGFBP3 with percent density or dense area. We found weak evidence that a twofold increase in prolactin and oestrone levels were associated, respectively, with an increase (by 1.7% (95% CI: -0.3, 3.7)) and a decrease (by 2.0% (95% CI: 0, 4.1)) in density after adjustment for BMI. CONCLUSIONS: These findings suggest that sex hormone and IGF levels are not associated with BMI-adjusted percent mammographic density in cross-sectional analyses of postmenopausal women and thus do not explain ethnic differences in density. Mammographic density may still, however, be influenced by much higher premenopausal hormone levels

    Comparison of Statistical Algorithms for the Detection of Infectious Disease Outbreaks in Large Multiple Surveillance Systems

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    A large-scale multiple surveillance system for infectious disease outbreaks has been in operation in England and Wales since the early 1990s. Changes to the statistical algorithm at the heart of the system were proposed and the purpose of this paper is to compare two new algorithms with the original algorithm. Test data to evaluate performance are created from weekly counts of the number of cases of each of more than 2000 diseases over a twenty-year period. The time series of each disease is separated into one series giving the baseline (background) disease incidence and a second series giving disease outbreaks. One series is shifted forward by twelve months and the two are then recombined, giving a realistic series in which it is known where outbreaks have been added. The metrics used to evaluate performance include a scoring rule that appropriately balances sensitivity against specificity and is sensitive to variation in probabilities near 1. In the context of disease surveillance, a scoring rule can be adapted to reflect the size of outbreaks and this was done. Results indicate that the two new algorithms are comparable to each other and better than the algorithm they were designed to replace

    Background risk of breast cancer and the association between physical activity and mammographic density

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