574 research outputs found

    Zonal Velocity Bands and the Solar Activity Cycle

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    We compare the zonal flow pattern in subsurface layers of the Sun with the distribution of surface magnetic features like sunspots and polar faculae. We demonstrate that in the activity belt, the butterfly pattern of sunspots coincides with the fast stream of zonal flows, although part of the sunspot distribution does spill over to the slow stream. At high latitudes, the polar faculae and zonal flow bands have similar distributions in the spatial and temporal domains.Comment: To appear in Solar Physic

    Some characteristics of the solar wind inferred from the study of sodium emission from cometary nuclei

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    Seventeen comets, having information on sodium D-line emission during their apparition, have been studied. The heliocentric distances corresponding to the sodium emission commencement or termination epoch are found to have a dependence on the phase of the solar cycle. For comets appearing during a solar maximum the sodium emission is detectable out to greater distances than, for the comets appearing during solar minimum. The sodium emission is also found to depend on heliographic latitude of the comet. It is concluded that the spatial properties of the solar wind during a solar maximum and minimum are responsible for the observed dependence

    K emission-line widths and the solar chromosphere

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    Closely spaced microphotometer tracings parallel to the dispersion of one excellent frame of a K-line time sequence have been utilized for a study of the nature of the K2v , K2R intensities in the case of the solar chromosphere. The frequency of occurrence of the categories of intensity ratio IK2v/IK2R are as follows: IK2v > IK2R = 45.3 per cent; IK2v = IK2R = 4.7 per cent; IK2v < IK2R = 25 per cent; IK2R = 0 = 22.3 per cent; IK2v = 0 =0.7 per cent. Two types of absorbing components are postulated to explain the pattern of observed K2v , K2R intensity ratios. One component with minor Doppler displacements acting on the normal K232 profile, where K2V > K2R, produces the cases K2v ≫ K2R , K2v = K2R , K2v < K2R . The other component arises from 'dark condensations' which are of size 3500 kms as seen in K2R. They have principally large down flowing velocities in the range 5-8 km/sec and are seen on K3 spectroheliograms with sizes of about 5000 kms, within the coarse network of emission. These 'dark condensations' give rise to the situation K2R = 0. K2-line widths are measured for all tracings where K2v , K2R are measurable simultaneously. The distribution curve of these widths is extremely sharp. The K2 emission source is identified with the bright fine mottles visible on the surface. Evidence for this interpretation comes from the study of auto-correlation functions of K2 intensity variations and the spacing between the bright fine mottles from both spectrograms and spectroheliograms. The life time of the fine mottling is 200 sec. The supergranular boundaries which constitute the coarse network come in two intensity classes. A low intensity network has the fine mottles as its principal contributor to the K emission. When the network is bright, the enhancement is caused by increased K emission due to the accumulation of magnetic fields at the supergranule boundary. The K2 widths of the low intensity supergranular boundary agree with the value found for the bright mottles. Those for the brighter network are lower than this value, similar to the K2 widths as seen in the active regions. It is concluded that bright fine mottling is responsible for the relation, found by Wilson and Bappu, between K emission line widths and absolute magnitudes of the stars. The paper discusses the solar cycle equivalents that stellar chromospheres can demonstrate and indicates a possible line of approach for successful detection of cyclic activity in stellar chromospheres

    Photometry of the solar corona of March 7, 1970

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    Isophotes obtained by equidensitometry techniques from four exposures of the March 7, 1970 corona are used for derivation of intensity distributions along the equator, poles, streamers and dark 'gaps' in the visible corona. The distributions differ from the van de Hulst curves for a maximum corona. The Kodaikanal measures agree well with the NRL measures of the outer corona made from a rocket coronagraph and together provide data from 1.2R⊙ to 8.0R⊙ along the solar equator. Radial intensity gradients for different position angles and the Ludendorff parameters obtained, characterize this corona as typical of the solar maximum

    Comparative prospective randomized open label trial of synbiotic (bifilac) as an add on therapy with standard treatment in patients with aphthous ulcer

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    Background: To trial the safety, efficacy and rapidity of response to a lozenges containing synbiotic in patients with minor aphthous ulcer.Methods: A total of 60 patients were enrolled for the trial after obtaining IEC approval and randomly allocated into two groups. Control “Group A” was administered with conventional treatment i.e., zytee and B complex for 2 weeks and trial “Group B” was administered with Bifilac along with conventional treatment for 2 weeks. The results of this trial were analyzed both subjectively and objectively.Results: Comparing with control group, where standard treatment was used with analgesics and B-complex, the trial group showed a quick relief of pain and helped in reducing mean size of ulcer.Conclusions: This trial was done with synbiotic lozenges in minor aphthous ulcers and it proved to be better alternative for them. Moreover, synbiotics have no adverse effects

    The spectrum of Comet Ikeya-Seki (1965f)

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    Spectroscopic observations of Comet Ikeya-Seki (1965f) with slit and slitless instruments are described. Sodium emission in the coma is seen from October 9 to November 1. A sodium tail extending upto 2° from the nucleus has been seen

    The G-O Rule and Waldmeier Effect in the Variations of the Numbers of Large and Small Sunspot Groups

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    We have analysed the combined Greenwich and Solar Optical Observing Network (SOON) sunspot group data during the period of 1874-2011 and determined variations in the annual numbers (counts) of the small, large and big sunspot groups (these classifications are made on the basis of the maximum areas of the sunspot groups). We found that the amplitude of an even-numbered cycle of the number of large groups is smaller than that of its immediately following odd-numbered cycle. This is consistent with the well known Gnevyshev and Ohl rule or G-O rule of solar cycles, generally described by using the Zurich sunspot number (Rz). During cycles 12-21 the G-O rule holds good for the variation in the number of small groups also, but it is violated by cycle pair (22, 23) as in the case of Rz. This behaviour of the variations in the small groups is largely responsible for the anomalous behaviour of Rz in cycle pair (22, 23). It is also found that the amplitude of an odd-numbered cycle of the number of small groups is larger than that of its immediately following even-numbered cycle. This can be called as `reverse G-O rule'. In the case of the number of the big groups, both cycle pairs (12, 13) and (22, 23) violated the G-O rule. In many cycles the positions of the peaks of the small, large, and big groups are different and considerably differ with respect to the corresponding positions of the Rz peaks. In the case of cycle 23, the corresponding cycles of the small and large groups are largely symmetric/less asymmetric (Waldmeier effect is weak/absent) with their maxima taking place two years later than that of Rz. The corresponding cycle of the big groups is more asymmetric (strong Waldmeier effect) with its maximum epoch taking place at the same time as that of Rz.Comment: 13 pages, 5 figures, 1 table, accepted by Solar Physic

    Techno-economic efficiency of marine fisheries in Gulf of Mannar Biosphere Reserve, India

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    Capture marine fisheries play a significant role in social, cultural, and economic dimensions of Indian capture fisheries that contributes to the blue growth strategies. Here the small-scale fisheries (SSF) constitute about 60 % and remaining 40 % large-scale fishing fleets (LSF). In this study, we have highlighted the techno-economic key indicators and technical efficiency of SSF and LSF of Gulf of Mannar Biosphere Reserve, India using Cobb-Douglas function, and Data Envelopment Analysis. The technical efficiency was slightly higher in SSF (TE = 0.961) with better quantity of fish produced per litre of fuel (5.05 kg) compared to the LSF (TE = 0.951). The labour efficiency such as value (87.56)andquantityoffishproducedperday(83.39kg)wasgreaterinLSFthantheSSF(87.56) and quantity of fish produced per day (83.39 kg) was greater in LSF than the SSF (7.07 and 14.26 kg, respectively). Though production cost was higher for LSF, the better gross revenue of 658.27wasgeneratedthanSSF(658.27 was generated than SSF (42.41) and it mainly related to higher engine power (150 – 200 hp) and longer fishing ground distance from the shore (117.50 km) for LSF than SSF (9.9 to 25 hp and 48.80 km, respectively). Results of the present study suggest that there is limited scope to improve the technical efficiency of the fishing fleet since both were operated at better efficiency conditions. However, the lower gross revenue per trip in SSF can be improved and higher production cost in LSF can be minimized by improving the performance of the fishing fleets in Biosphere Reserve

    An evaluation of possible mechanisms for anomalous resistivity in the solar corona

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    A wide variety of transient events in the solar corona seem to require explanations that invoke fast reconnection. Theoretical models explaining fast reconnection often rely on enhanced resistivity. We start with data derived from observed reconnection rates in solar flares and seek to reconcile them with the chaos-induced resistivity model of Numata & Yoshida (2002) and with resistivity arising out of the kinetic Alfv\'en wave (KAW) instability. We find that the resistivities arising from either of these mechanisms, when localized over lengthscales of the order of an ion skin depth, are capable of explaining the observationally mandated Lundquist numbers.Comment: Accepted, Solar Physic

    Screening the medicines for Malaria Venture "Malaria Box" against the Plasmodium falciparum aminopeptidases, M1, M17 and M18

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    Malaria is a parasitic disease that remains a global health burden. The ability of the parasite to rapidly develop resistance to therapeutics drives an urgent need for the delivery of new drugs. The Medicines for Malaria Venture have compounds known for their antimalarial ac- tivity, but not necessarily the molecular targets. In this study, we assess the ability of the “MMV 400” compounds to inhibit the activity of three metalloaminopeptidases from Plasmo- dium falciparum, PfA-M1, PfA-M17 and PfM18 AAP. We have developed a multiplex assay system to allow rapid primary screening of compounds against all three metalloaminopepti- dases, followed by detailed analysis of promising compounds. Our results show that there were no PfM18AAP inhibitors, whereas two moderate inhibitors of the neutral aminopepti- dases PfA-M1 and PfA-M17 were identified. Further investigation through structure-activity relationship studies and molecular docking suggest that these compounds are competitive inhibitors with novel binding mechanisms, acting through either non-classical zinc coordina- tion or independently of zinc binding altogether. Although it is unlikely that inhibition of PfA- M1 and/or PfA-M17 is the primary mechanism responsible for the antiplasmodial activity re- ported for these compounds, their detailed characterization, as presented in this work, pave the way for their further optimization as a novel class of dual PfA-M1/PfA-M17 inhibitors uti- lising non-classical zinc binding groups
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