Variability And Correlation Of Agronomic Characters Of Mungbean Germplasm And Their Utilization For Variety Improvement Program Lukman Hakim

Information on the variability and correlation between agronomic characters of mungbean accessions with their yield are important for supporting breeding program of the plant. A total of 350 mungbean accessions were evaluated at Muara Experimental Farm, Indonesian Center for Food Crops Research and Development, Bogor, during the dry season of 2005. The experiment was conducted in a completely randomized block design with three replications. Each accession was planted in two rows of 5 m long. Plant spacing was 40 cm x 20 cm, two plants per hill. Correlation and path coefficient analyses were used to quantifythe magnitude of the relationship between yield components and grain yield. The variability among the accessions was significant for most of the characters studied, especially for days to maturity, plant height, pods per plant, and seed size. Among the yield components, the number of pods per plant and plant height positively correlated with the grain yield, but theseed size negatively correlated with grain yield. The direct effects of the number of pods per plant and plant height on seed yield as indicated by path coefficient were the highest, while other causal effects were small or negative. Yield variation (1- R2) attributable to the nine yield component variables was slightly high (61.23%), which means that mungbean accessions with high grain yield should have sufficient plant height and high number of pods per plant. Therefore, these parameters (number of pods per plant and plant height) can be used as the selection criteria in mungbean breeding program. These criteria can be visualized during bulk selection on the early generation stage of F2 to F4, and subsequently on line development of individual plant (pedigree) of F5

Radiation variability and correlation studies

The determination of variability of the emitted and reflected components of outgoing radiation from the earth-atmosphere system is discussed. The effects of variability on climate and weather are considered, and meteorological and climate variables to be correlated with radiation budget measurements are determined

The correlations between optical variability and physical parameters of quasars in SDSS Stripe 82

We investigate the optical variability of 7658 quasars from SDSS Stripe 82. Taking advantage of a larger sample and relatively more data points for each quasar, we estimate variability amplitudes and divide the sample into small bins of redshift, rest-frame wavelength, black hole mass, Eddington ratio and bolometric luminosity respectively, to investigate the relationships between variability and these parameters. An anti-correlation between variability and rest-frame wavelength is found. The variability amplitude of radio-quiet quasars shows almost no cosmological evolution, but that of radio-loud ones may weakly anti-correlate with redshift. In addition, variability increases as either luminosity or Eddington ratio decreases. However, the relationship between variability and black hole mass is uncertain; it is negative when the influence of Eddington ratio is excluded, but positive when the influence of luminosity is excluded. The intrinsic distribution of variability amplitudes for radio-loud and radio-quiet quasars are different. Both radio-loud and radio-quiet quasars exhibit a bluer-when-brighter chromatism. Assuming that quasar variability is caused by variations of accretion rate, the Shakura-Sunyaev disk model can reproduce the tendencies of observed correlations between variability and rest-frame wavelength, luminosity as well as Eddington ratio, supporting that changes of accretion rate plays an important role in producing the observed optical variability. However, the predicted positive correlation between variability and black hole mass seems to be inconsistent with the observed negative correlation between them in small bins of Eddington ratio, which suggests that other physical mechanisms may still need to be considered in modifying the simple accretion disk model.Comment: 51 pages, 28 figures, 2 tables, ApJ accepte

Study of the Nuclear Activity of the Seyfert Galaxy NGC 7469 over the Period of Observations 2008-2014

We present results of multicolor UBVRI observations of the type 1 Seyfert galaxy (SyG 1) NGC 7469 carried out at the 1.5-meter telescope of the Maidanak Observatory (Uzbekistan) in 2008-2014. Analysis of the light curves indicates the presence of another slow flare of a long-term variability in 2009-2014 with a maximum in 2011-2012. We investigate properties of the long-term variability in 2009-2014, present (U-B)-(B-V) color diagrams for maxima and minima of NGC 7469 nuclear variability using various apertures and compare them with the black-body gas radiation which models the accretion disk radiation. Color-index measurements shows that the color becomes bluer at maximum brightness, indicating a higher temperature of the accretion disk. We have analysed the relation of X-ray and optical variability of NGC 7469 in 2008 and 2009 in comparison with the activity minimum in 2003. In 2008 the correlation coefficient between the X-ray and optical radiation is close to 0.5. Such poor correlation can be explained by the influence of an SN 1a explosion in close proximity to the nucleus of NGC 7469. The SN manifests itself in the optical band but does not affect the X-ray variability pattern. Comparison of the variability data in 2009 reveals a good correlation between the optical (U band) and the X-ray (7-10 keV) variability with the correlation coefficient of about 0.93. The correlation coefficient and the lag depend on the wavelength in the optical and X-ray bands. The lag between the X-ray and optical fluxes in 2009 is 2-4 days. In 2003 the lag is almost zero.Comment: 14 pages,6 figures; updated version of the paper published in Astronomy Letters, April 2017 issue; colored figure

AGN X-ray variability in the XMM-COSMOS survey

We took advantage of the observations carried out by XMM in the COSMOS field during 3.5 years, to study the long term variability of a large sample of AGN (638 sources), in a wide range of redshift (0.1<z<3.5) and X-ray luminosity ($10^{41}<$L(2-10)$<10^{45.5}$). Both a simple statistical method to asses the significance of variability, and the Normalized Excess Variance ($\sigma^{2}_{rms}$) parameter, where used to obtain a quantitative measurement of the variability. Variability is found to be prevalent in most AGN, whenever we have good statistic to measure it, and no significant differences between type-1 and type-2 AGN were found. A flat (slope -0.23+/-0.03) anti-correlation between $\sigma^{2}_{rms}$ and X-ray luminosity is found, when significantly variable sources are considered all together. When divided in three redshift bins, the anti-correlation becomes stronger and evolving with z, with higher redshift AGN being more variable. We prove however that this effect is due to the pre-selection of variable sources: considering all the sources with available $\sigma^{2}_{rms}$ measurement, the evolution in redshift disappears. For the first time we were also able to study the long term X-ray variability as a function of $M_{\rm BH}$ and Eddington ratio, for a large sample of AGN spanning a wide range of redshift. An anti-correlation between $\sigma^{2}_{rms}$ and $M_{\rm BH}$ is found, with the same slope of the anti-correlation between $\sigma^{2}_{rms}$ and X-ray luminosity, suggesting that the latter can be a byproduct of the former one. No clear correlation is found between $\sigma^{2}_{rms}$ and the Eddington ratio in our sample. Finally, no correlation is found between the X-ray $\sigma^{2}_{rms}$ and the optical variability.Comment: 14 Pages, 13 figures. Accepted to the Astrophysical Journal on December 6, 201

SS 433: Radio/X-ray anti-correlation and fast-time variability

We briefly review the Galactic microquasar SS 433/W50 and present a new RXTE spectral and timing study. We show that the X-ray flux decreases during radio flares, a behavior seen in other microquasars. We also find short time-scale variability unveiling emission regions from within the binary system.Comment: 4 pages, 3 figures, mq.sty included. A higher resolution version can be found at http://aurora.physics.umanitoba.ca/~samar/4MQ/ss433/. Proceedings of the 4th Microquasar Workshop, eds. Ph. Durouchoux, Y. Fuchs and J. Rodriguez, published by the Center for Space Physics: Kolkata (in press

An accretion disc model for quasar optical variability

Some different correlations between optical-UV variability and other quasar properties, such as luminosity, black hole mass and rest-frame wavelength, were discovered. The positive correlation between optical-UV variability amplitude and black hole mass was first found by Wold et al., and this was confirmed by Wilhite et al. We suggest that the accretion disk model can explain these correlations, provided the optical-UV variability is triggered by the change of accretion rate. The disk temperature of accretion discs decreases with increasing black hole mass, which leads to systematical spectral shape difference with black hole mass even if the black hole is accreting at the same rate m_dot (m_dot = M_dot / M_dotEdd). The observed positive correlation between optical-UV variability and black hole mass can be well reproduced by our model calculations, if the mean accretion rate m_dot0 ~ 0.1 with variation of m_delta ~ 0.4 - 0.5 m_dot0. We also found that the observed correlations of optical-UV variability amplitude with luminosity or rest-frame wavelength can be qualitatively explained by this accretion disc model.Comment: 4 pages, 4 figures, accepted for publication in MNRAS Letter