758 research outputs found

    Multi-wavelength Diagnostics of the Precursor and Main phases of an M1.8 Flare on 2011 April 22

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    We study the temporal, spatial and spectral evolution of the M1.8 flare, which occurred in NOAA AR 11195 (S17E31) on 22 April 2011, and explore the underlying physical processes during the precursors and their relation to the main phase. The study of the source morphology using the composite images in 131 {\deg}A wavelength observed by the SDO/AIA and 6-14 keV revealed a multiloop system that destabilized systematically during the precursor and main phases. In contrast, HXR emission (20-50 keV) was absent during the precursor phase, appearing only from the onset of the impulsive phase in the form of foot-points of emitting loop/s. This study has also revealed the heated loop-top prior to the loop emission, although no accompanying foot-point sources were observed during the precursor phase. We estimate the flare plasma parameters viz. T, EM, power-law index, and photon turn-over energy by forward fitting RHESSI spectral observations. The energy released in the precursor phase was thermal and constituted ~1 per cent of the total energy released during the flare. The study of morphological evolution of the filament in conjunction with synthesized T and EM maps has been carried out which reveals (a) Partial filament eruption prior to the onset of the precursor emission, (b) Heated dense plasma over the polarity inversion line and in the vicinity of the slowly rising filament during the precursor phase. Based on the implications from multi-wavelength observations, we propose a scheme to unify the energy release during the precursor and main phase emissions in which, the precursor phase emission has been originated via conduction front formed due to the partial filament eruption. Next, the heated leftover S-shaped filament has undergone slow rise and heating due to magnetic reconnection and finally erupted to produce emission during the impulsive and gradual phases.Comment: 16 Pages, 11 Figures, Accepted for Publication in MNRAS Main Journa

    MOLECULAR DETECTION OF HUMAN RHINOVIRUS IN RESPIRATORY SAMPLES OF SWINE FLU NEGATIVE NORTH INDIAN CHILDREN WITH FLU-LIKE ILLNESS

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    Objectives: Flu-like illness may also be caused by different respiratory viruses other than influenza. Human rhinovirus (HRV) shows almost flu-likesymptoms. The purpose of this study is the molecular detection of HRV in throat swab of swine flu negative North Indian children during the years2012 and 2013. Reverse transcriptase (RT) - polymerase chain reaction (PCR) amplification of 5'non-coding region (NCR) was used for HRV detectionfollowed by cell culture isolation of HRV.Methods: PCR confirmed swine flu negative throat swab samples were collected from the Department of Microbiology, Sanjay Gandhi Post GraduateInstitute of Medical Sciences, Lucknow, Uttar Pradesh, India. The RNA isolation of samples was done using the QIAampViral RNA Mini Kit (Qiagen),followed by single step RT-PCR amplification (AgPath-ID, Life Technologies). All PCR positive HRV samples were cell cultured in HeLa and HEp-2 celllines for viral isolation.®Results: 135 swine flu negative throat swab samples were examined. Out of which 34 samples (25.2%) were found HRV positive by RT-PCR, while onlyfour samples (11.8%) were culture positive on HeLa cell line. Younger children (0-4 year) were found more susceptible to HRV infection. This studyindicated the highest prevalence of HRV (37.0%) during the months (September-October) of the Autumn season in 2012 and 57% in Winter-springseason (February-March) during 2013.Conclusion: HRV may be a cause of flu-like symptoms in swine flu suspected North Indian children with a higher rate during Autumn and Springseason. Molecular detection of HRV using RT-PCR is more sensitive than cell culture assay.Keywords: Human rhinovirus, Swine flu, Influenza-like illness, Lower respiratory tract infections

    Effects of individual and combined heat and drought stress during seed filling on the oxidative metabolism and yield of chickpea (Cicer arietinum) genotypes differing in heat and drought tolerance

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    Drought and heat stress are two major constraints that limit chickpea (Cicer arietinum L.) yield, particularly during seed filling. The present study aimed (i) to assess the individual and combined effects of drought and heat stress on oxidative metabolism during seed filling, and (ii) to determine any genetic variation in oxidative metabolism among genotypes differing in drought and heat tolerance and sensitivity. The plants were raised in outdoor conditions with two different times of sowing, one in November (normal-sown, temperatures 32°C−20°C (day–night) during seed filling). Plants were regularly irrigated to prevent any water shortage until the water treatments were applied. At both sowing times, the drought treatment was applied during seed filling (at ∼75% podding) by withholding water from half of the pots until the relative leaf water content (RLWC) of leaves on the top three branches reached 42–45%, whereas leaves in the fully irrigated control plants were maintained at RLWC 85–90%. Drought-stressed plants were then rewatered and maintained under fully irrigated conditions until maturity. Several biochemical parameters were measured on the leaves and seeds at the end of the stress treatments, and seed yield and aboveground biomass were measured at maturity. Individual and combined stresses damaged membranes, and decreased PSII function and leaf chlorophyll content, more so under the combined stress treatment. The levels of oxidative molecules (malondialdehyde (MDA) and H2O2) markedly increased compared with the control plants in all stress treatments, especially across genotypes in the combined heat + drought stress treatment (increases in leaves: MDA 5.4–8.4-fold and H2O2 5.1–7.1-fold; in seeds: MDA 1.9–3.3-fold and H2O2 3.8–7.9-fold). The enzymatic and non-enzymatic antioxidants related to oxidative metabolism increased under individual stress treatments but decreased in the combined heat + drought stress treatment. Leaves had higher oxidative damage than seeds, and this likely inhibited their photosynthetic efficiency. Yields were reduced more by drought stress than by heat stress, with the lowest yields in the combined heat + drought stress treatment. Heat- and drought-tolerant genotypes suffered less damage and had higher yields than the heat- and drought-sensitive genotypes under the individual and combined stress treatments, suggesting partial cross-tolerance in these genotypes. A drought-tolerant genotype ICC8950 produced more seed yield under the combined heat + drought stress than other genotypes, and this was associated with low oxidative damage in leaves and seeds
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