Signature of Inverse Compton emission from blazars

Blazars are classified into high, intermediate and low energy peaked sources based on the location of their synchrotron peak. This lies in infra-red/optical to ultra-violet bands for low and intermediate peaked blazars. The transition from synchrotron to inverse Compton emission falls in the X-ray bands for such sources. We present the spectral and timing analysis of 14 low and intermediate energy peaked blazars ob- served with XMMNewton spanning 31 epochs. Parametric fits to X-ray spectra helps constrain the possible location of transition from the high energy end of the syn- chrotron to the low energy end of the inverse Compton emission. In seven sources in our sample, we infer such a transition and constrain the break energy in the range 0.6 10 keV. The Lomb-Scargle periodogram is used to estimate the power spectral density (PSD) shape. It is well described by a power law in a majority of light curves, the index being flatter compared to general expectation from AGN, ranging here between 0.01 and 1.12, possibly due to short observation durations resulting in an absence of long term trends. A toy model involving synchrotron self-Compton (SSC) and exter- nal Compton (EC; disk, broad line region, torus) mechanisms are used to estimate magnetic field strength 6 0.03 - 0.88 G in sources displaying the energy break and infer a prominent EC contribution. The timescale for variability being shorter than synchrotron cooling implies steeper PSD slopes which are inferred in these sources.Comment: 24 pages, 6 Tables, 13 figures, Accepted for MNRA

The Hard X-ray emission of the blazar PKS 2155--304

The synchrotron peak of the X-ray bright High Energy Peaked Blazar (HBL) PKS 2155$-$304 occurs in the UV-EUV region and hence its X-ray emission (0.6--10 keV) lies mostly in the falling part of the synchrotron hump. We aim to study the X-ray emission of PKS 2155$-$304 during different intensity states in 2009$-$2014 using XMM$-$Newton satellite. We studied the spectral curvature of all of the observations to provide crucial information on the energy distribution of the non-thermal particles. Most of the observations show curvature or deviation from a single power-law and can be well modeled by a log parabola model. In some of the observations, we find spectral flattening after 6 keV. In order to find the possible origin of the X-ray excess, we built the Multi-band Spectral Energy distribution (SED). We find that the X-ray excess in PKS 2155--304 is difficult to fit in the one zone model but, could be easily reconciled in the spine/layer jet structure. The hard X-ray excess can be explained by the inverse Comptonization of the synchrotron photons (from the layer) by the spine electrons.Comment: 14 pages, 7 Figures, Accepted for publication in Ap

E-Learning in India: Experiences, Issues & Challenges

There is massive potential in the higher education space spread across the Asian continent especially in countries like India and China. Global players operating in this space are eyeing these markets. This throws opportunities as well as challenges. There are many players, local as well as global, who have experimented or are experimenting online (pure play) or blended models in education. There have been failures and mistakes, which have thrown lot of learning. As a result players have improvised their offers. Online education is now working. Though the progression is slow, it is expected to grow exponential in the coming years. E-learning is network enabled learning. There is a race to get into e-learning space in India given the scope and size of this market in India. But many organizations and academic institutions trying to foray into E-learning are getting imbalanced due to the lack of proper understanding of the market place and internal/external requirements. IT assimilation throws unimaginable challenges. What should be the operating strategy, deliverable value, approach, processes and technology assimilation strategies so that the entire organization moves towards successful implementation of the E-learning project without compromising on its existing competencies is a serious matter for researchers to ponder. This paper tries to answer some of the above issues with the help of the experiences gained form one of the largest online education project launched and running quite successfully in India. The suggested framework evolves around discovery of a collaboration model with software and connectivity service providers and criteria of collaboration to be drawn from the learner needs and requirement. The collaboration should balance to achieve necessary value proposition for the intended learner segment by careful crafting of the Learner Centric Value Chain

Drought and heat tolerance in chickpea

Chickpea is largely grown rainfed on residual soil moisture after the rainy season. Terminal drought is a major constraint to chickpea production, particularly in the semi-arid tropics. Similarly, exposure of chickpea to heat stress (≥35C) at flowering and podding is known to result in drastic reductions in seed yields. Efforts have been made to develop cultivars that can escape (early maturity) or avoid/tolerate (greater extraction of water from the soil, enhanced water use efficiency) terminal drought. Large genetic variations exist for reproductive stage heat tolerance in chickpea. Many heat tolerant genotypes have been identified through screening of germplasm/breeding lines under heat stress conditions in the field. A heat tolerant breeding line ICCV92944 has been released for cultivation in Myanmar (as Yezin 6) and India (as JG 14)

A gene producing one to nine flowers per flowering node in chickpea

Chickpea (Cicer arietinum L.) has a racemose type of inflorescence and at each axis of the raceme usually one or two and rarely three flowers are borne. Plants producing 3 to 9 flowers, arranged in a cymose inflorescence, at many axis of the raceme, were identified in F2 of an interspecific cross ICC 5783 (C. arietinum) × ICCW 9 (C. reticulatum) in which both the parents involved were single-flowered. A spontaneous mutation in one of the two parents or in the F1 was suspected. However, the possibility for establishment of a rare recombination of two interacting recessive genes could not be ruled out. The number of pods set varied from 0 to 5 in each cyme. Inheritance studies indicated that a single recessive gene, designated cym, is responsible for cymose inflorescence. The allelic relationship of cym with sfl, a gene for double-flowered trait, was studied from a cross involving multiflowered plants and the double-flowered line ICC 4929. The cym gene was not allelic to sfl, suggesting that two loci control the number of flowers per peduncle in chickpea. The cym locus segregated independently of the locus sfl, ifc (inhibitor of flower color) and blv (bronze leave)