62 research outputs found
On the origin of the various types of radio emission in GRS 1915+105
We investigate the association between the radio ``plateau'' states and the
large superluminal flares in GRS 1915+105 and propose a qualitative scenario to
explain this association. We identify several candidate superluminal flare
events from available monitoring data on this source and analyze the
contemporaneous RXTE pointed observations. We detect a strong correlation
between the average X-ray flux during the ``plateau'' state and the total
energy emitted in radio during the subsequent radio flare. We find that the
sequence of events is similar for all large radio flares with a fast rise and
exponential decay morphology. Based on these results, we propose a qualitative
scenario in which the separating ejecta during the superluminal flares are
observed due to the interaction of the matter blob ejected during the X-ray
soft dips, with the steady jet already established during the ``plateau''
state. This picture can explain all types of radio emission observed from this
source in terms of its X-ray emission characteristics.Comment: Corrected typo in the author names, contents unchanged, accepted in
Ap
Evidence for Synchrotron Bubbles from GRS 1915+105
We present GMRT observations of the Galactic microquasar GRS 1915+105 at 1.28
GHz for 8 days from 2001 June 18 to July 1. We have seen several isolated radio
flares of varying magnitudes (20 - 50 mJy) and durations (6 - 35 min) and we
model them as due to adiabatically expanding synchrotron emitting clouds
(synchrotron bubbles) ejected from the accretion disk. By applying this model,
we provide a new method to estimate the electron power-law index p, hence the
spectral index, from single frequency radio observations. This method does not
require correction for the optical depth time delay effects which may be
important in the case of optically thick radio emission. Using our estimated
value of p and simultaneous multiwavelength data from literature, we have
calculated the time of ejection of the synchrotron plasma and the time delays
at different observed frequencies. Our estimates are in good agreement with the
observed time delays.Comment: Accepted for publication in A&A Letter
Development of High Yielding Fusarium Wilt Resistant Cultivar by Pyramiding of “Genes” Through Marker-Assisted Backcrossing in Chickpea (Cicer arietinum L.)
Pusa 391, a mega desi chickpea variety with medium maturity duration is extensively cultivated in the Central Zone of India. Of late, this variety has become susceptible to Fusarium wilt (FW), which has drastic impact on its yield. Presence of variability in the wilt causing pathogen, Fusarium oxysporum f.sp. ciceri (foc) across geographical locations necessitates the role of pyramiding for FW resistance for different races (foc 1,2,3,4 and 5). Subsequently, the introgression lines developed in Pusa 391 genetic background were subjected to foreground selection using three SSR markers (GA16, TA 27 and TA 96) while 48 SSR markers uniformly distributed on all chromosomes, were used for background selection to observe the recovery of recurrent parent genome (RPG). BC1F1 lines with 75–85% RPG recovery were used to generate BC2F1. The plants that showed more than 90% RPG recovery in BC2F1 were used for generating BC3F1. The plants that showed more than 96% RPG recovery were selected and selfed to generate BC3F3. Multi-location evaluation of advanced introgression lines (BC2F3) in six locations for grain yield (kg/ha), days to fifty percent flowering, days to maturity, 100 seed weight and disease incidence was done. In case of disease incidence, the genotype IL1 (BGM 20211) was highly resistant to FW in Junagarh, Indore, New Delhi, Badnapur and moderately resistant at Sehore and Nandyal. GGE biplot analysis revealed that IL1(BGM20211) was the most stable genotype at Junagadh, Sehore and Nandyal. GGE biplot analysis revealed that IL1(BGM 20211) and IL4(BGM 20212) were the top performers in yield and highly stable across six environments and were nominated for Advanced Varietal Trials (AVT) of AICRP (All India Coordinated Research Project on Chickpea) in 2018–19. BGM20211 and BGM 20212 recorded 29 and 28.5% average yield gain over the recurrent parent Pusa 391, in the AVT-1 and AVT-2 over five environments. Thus, BGM20211 was identified for release and notified as Pusa Manav/Pusa Chickpea 20211 for Madhya Pradesh, Gujarat and Maharashtra, Southern Rajasthan, Bundhelkhand region of Uttar Pradesh states by the Central Sub-Committees on Crop Standards, Notification and Release of Varieties of Agricultural Crops, Ministry of Agriculture and Farmers Welfare, Government of India, for commercial cultivation in India (Gazette notification number S.O.500 (E) dt. 29-1-2021).Such pyramided lines give resilience to multiple races of fusarium wilt with added yield advantage
New high-resolution radio observations of the SNR CTB 80
We report new high resolution and high sensitivity radio observations of the
extended supernova remnant (SNR) CTB 80 (G69.0+2.7) at 240 MHz, 324 MHz, 618
MHz, and 1380 MHz. The imaging of CTB 80 at 240 MHz and 618 MHz was performed
using the Giant Metrewave Radio Telescope (GMRT) in India. The observations at
324 MHz and 1380 MHz were obtained using the Very Large Array (VLA, NRAO) in
its C and D configurations. The new radio images reveal faint extensions for
the asymmetric arms of CTB 80. The arms are irregular with filaments and clumps
of size 1' (or 0.6 pc at a distance of 2 kpc). The radio image at 1380 MHz is
compared with IR and optical emission. The correspondence IR/radio is excellent
along the N arm of CTB 80. Ionized gas observed in the [SII] line perfectly
matches the W and N edges of CTB 80. The central nebula associated with the
pulsar PSR B1951+32 was investigated with an angular resolution of 10" x 6".
The new radio image obtained at 618 MHz shows with superb detail structures in
the 8' x 4' E-W ``plateau'' nebula that hosts the pulsar on its western
extreme. A twisted filament, about 6' in extent (~3.5 pc), trails behind the
pulsar in an approximate W-E direction. In the bright ``core'' nebula (size
\~45"), located to the W of the plateau, the images show a distortion in the
morphology towards the W; this feature corresponds to the direction in which
the pulsar escapes from the SNR with a velocity of ~240 km/s. Based on the new
observations, the energetics of the SNR and of the PWN are investigated.Comment: 11 pages, Latex, 6 eps figures, To appear in AJ Vol 126., No. 5,
November 200
Radio, millimeter and optical monitoring of GRB030329 afterglow: Constraining the double jet model
We present radio, millimeter and optical observations of the afterglow of
GRB030329. UBVR_{C}I_{C} photometry is presented for a period of 3 hours to 34
days after the burst. Radio monitoring at 1280 MHz has been carried out using
the GMRT for more than a year. Simultaneous millimeter observations at 90 GHz
and 230 GHz have been obtained from the Swedish-ESO Submillimeter Telescope
(SEST) and the IRAM-PdB interferometer over more than a month following the
burst. We use these data to constrain the double jet model proposed by Berger
et al. (2003) for this afterglow. We also examine whether instead of the two
jets being simultaneously present, the wider jet could result from the
initially narrow jet, due to a fresh supply of energy from the central engine
after the ``jet break''.Comment: 31 pages, 5 figures, Accepted for publication in A&A main journal.
Table 2 will be available only through the electronic version of the journa
A bibliography of parasites and diseases of marine and freshwater fishes of India
With the increasing demand for fish as human food, aquaculture both in freshwater
and salt water is rapidly developing over the world. In the developing countries,
fishes are being raised as food. In many countries fish farming is a very important
economic activity. The most recent branch, mariculture, has shown advances in
raising fishes in brackish, estuarine and bay waters, in which marine, anadromous and
catadromous fishes have successfully been grown and maintained
Guidelines for the use and interpretation of assays for monitoring autophagy (3rd edition)
In 2008 we published the first set of guidelines for standardizing research in autophagy. Since then, research on this topic has continued to accelerate, and many new scientists have entered the field. Our knowledge base and relevant new technologies have also been expanding. Accordingly, it is important to update these guidelines for monitoring autophagy in different organisms. Various reviews have described the range of assays that have been used for this purpose. Nevertheless, there continues to be confusion regarding acceptable methods to measure autophagy, especially in multicellular eukaryotes. For example, a key point that needs to be emphasized is that there is a difference between measurements that monitor the numbers or volume of autophagic elements (e.g., autophagosomes or autolysosomes) at any stage of the autophagic process versus those that measure fl ux through the autophagy pathway (i.e., the complete process including the amount and rate of cargo sequestered and degraded). In particular, a block in macroautophagy that results in autophagosome accumulation must be differentiated from stimuli that increase autophagic activity, defi ned as increased autophagy induction coupled with increased delivery to, and degradation within, lysosomes (inmost higher eukaryotes and some protists such as Dictyostelium ) or the vacuole (in plants and fungi). In other words, it is especially important that investigators new to the fi eld understand that the appearance of more autophagosomes does not necessarily equate with more autophagy. In fact, in many cases, autophagosomes accumulate because of a block in trafficking to lysosomes without a concomitant change in autophagosome biogenesis, whereas an increase in autolysosomes may reflect a reduction in degradative activity. It is worth emphasizing here that lysosomal digestion is a stage of autophagy and evaluating its competence is a crucial part of the evaluation of autophagic flux, or complete autophagy. Here, we present a set of guidelines for the selection and interpretation of methods for use by investigators who aim to examine macroautophagy and related processes, as well as for reviewers who need to provide realistic and reasonable critiques of papers that are focused on these processes. These guidelines are not meant to be a formulaic set of rules, because the appropriate assays depend in part on the question being asked and the system being used. In addition, we emphasize that no individual assay is guaranteed to be the most appropriate one in every situation, and we strongly recommend the use of multiple assays to monitor autophagy. Along these lines, because of the potential for pleiotropic effects due to blocking autophagy through genetic manipulation it is imperative to delete or knock down more than one autophagy-related gene. In addition, some individual Atg proteins, or groups of proteins, are involved in other cellular pathways so not all Atg proteins can be used as a specific marker for an autophagic process. In these guidelines, we consider these various methods of assessing autophagy and what information can, or cannot, be obtained from them. Finally, by discussing the merits and limits of particular autophagy assays, we hope to encourage technical innovation in the field
Late-time cosmology with 21cm intensity mapping experiments
Extensive update with new array specifications. Conclusions unchanged. Matches published versionExtensive update with new array specifications. Conclusions unchanged. Matches published versionExtensive update with new array specifications. Conclusions unchanged. Matches published versionWe present a framework for forecasting cosmological constraints from future neutral hydrogen intensity mapping experiments at low to intermediate redshifts. In the process, we establish a simple way of comparing such surveys with optical galaxy redshift surveys. We explore a wide range of experimental configurations and assess how well a number of cosmological observables (the expansion rate, growth rate, and angular diameter distance) and parameters (the densities of dark energy and dark matter, spatial curvature, the dark energy equation of state, etc.) will be measured by an extensive roster of upcoming experiments. A number of potential contaminants and systematic effects are also studied in detail. The overall picture is encouraging -- if autocorrelation calibration can be controlled to a sufficient level, Phase I of the SKA should be able to constrain the dark energy equation of state about as well as a DETF Stage IV galaxy redshift survey like Euclid, in roughly the same timeframe
Genetic variation at twentythree microsatellite loci in sixteen human populations
Artículo científico -- Universidad de Costa Rica, Instituto de Investigaciones en Salud. 1999We have analysed genetic variation at 23 microsatellite loci in a global sample of 16 ethnically and geographically diverse human populations. On the basis of their ancestral heritage and geographic locations, the studied populations can be divided into five major groups, viz. African, Caucasian, Asian Mongoloid, American Indian and Pacific Islander. With respect to the distribution of alleles at the 23 loci, large variability exists among the examined populations. However, with the exception of the American Indians and the Pacific Islanders, populations within a continental group show a greater degree of similarity. Phylogenetic analyses based on allele frequencies at the examined loci show that the first split of the present-day human populations had occurred between the Africans and all of the non-African populations, lending support to an African origin of modern human populations. Gene diversity analyses show that the coefficient of gene diversity estimated from the 23 loci is, in general, larger for populations that have remained isolated and probably of smaller effective sizes, such as the American Indians and the Pacific Islanders. These analyses also demonstrate that the component of total gene diversity, which is attributed to variation between groups of populations, is significantly larger than that among populations within each group. The empirical data presented in this work and their analyses reaffirm that evolutionary histories and the extent of genetic variation among human populations can be studied using microsatellite loci.Universidad de Costa Rica. Instituto de Investigaciones en SaludUCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias de la Salud::Instituto de Investigaciones en Salud (INISA
- …