X-ray activity cycle on the active ultra-fast rotator AB Dor A? Implication of correlated coronal and photometric variability

Although chromospheric activity cycles have been studied in a larger number of late-type stars for quite some time, very little is known about coronal activity-cycles in other stars and their similarities or dissimilarities with the solar activity cycle. While it is usually assumed that cyclic activity is present only in stars of low to moderate activity, we investigate whether the ultra-fast rotator AB Dor, a K dwarf exhibiting signs of substantial magnetic activity in essentially all wavelength bands, exhibits a X-ray activity cycle in analogy to its photospheric activity cycle of about 17 years and possible correlations between these bands. We analysed the combined optical photometric data of AB Dor A, which span ~35 years. Additionally, we used ROSAT and XMM-Newton X-ray observations of AB Dor A to study the long-term evolution of magnetic activity in this active K dwarf over nearly three decades and searched for X-ray activity cycles and related photometric brightness changes. AB Dor A exhibits photometric brightness variations ranging between 6.75 < Vmag < 7.15 while the X-ray luminosities range between 29.8 < log LX [erg/s] < 30.2 in the 0.3-2.5 keV. As a very active star, AB Dor A shows frequent X-ray flaring, but, in the long XMM-Newton observations a kind of basal state is attained very often. This basal state probably varies with the photospheric activity-cycle of AB Dor A which has a period of ~17 years, but, the X-ray variability amounts at most to a factor of ~2, which is, much lower than the typical cycle amplitudes found on the Sun.Comment: 10 page

X-raying the coronae of HD~155555

We present an analysis of the high-resolution Chandra observation of the multiple system, HD 155555 (an RS CVn type binary system, HD 155555 AB, and its spatially resolved low-mass companion HD 155555 C). This is an intriguing system which shows properties of both an active pre-main sequence star and a synchronised (main sequence) binary. We obtain the emission measure distribution, temperature structures, plasma densities, and abundances of this system and compare them with the coronal properties of other young/active stars. HD 155555 AB and HD 155555 C produce copious X-ray emission with log Lx of 30.54 and 29.30, respectively, in the 0.3-6.0 keV energy band. The light curves of individual stars show variability on timescales of few minutes to hours. We analyse the dispersed spectra and reconstruct the emission measure distribution using spectral line analysis. The resulting elemental abundances exhibit inverse first ionisation potential effect in both cases. An analysis of He-like triplets yields a range of coronal electron densities ~10^10-10^13 cm-3. Since HD 155555 AB is classified both as an RS CVn and a PMS star, we compare our results with those of other slightly older active main-sequence stars and T Tauri stars, which indicates that the coronal properties of HD 155555 AB closely resemble that of an older RS CVn binary rather than a younger PMS star. Our results also suggests that the properties of HD 155555 C is very similar to those of other active M dwarfs.Comment: 17 pages, 23 figues, Accepted in Ap

Artisanal Fishery for Prawns at Uppada near Kakinada in Andhra Pradesh coast

Uppada (Lat. 17° 6' N, Long 82° 23' E) is an important marine fish landing centre of Kakinada region where prawns form about 4% to 95% in thetotal fish landings. Twenty three species of penaeid prawns and 4 species of non-penaeid prawns contribute to the prawn fishery of which 10 species of penaeid prawns and 3 species of non-penaeid prawns form regular fishery, throughout the year. Data on prawn catches at Uppada collected for aperiod of 5 years from 1979 to 1983 show that an average 501.5 t of piawns are landed per annum at this centre, accounting for 24.1 % of the total fish landings. Penaeid prawns formed 82.4% in total prawn landings and 19.8% in total fish landings

PLANT DISESASE DETECTION BY USING IMAGE PROCESSING TECHNIQUES

In agriculture research of automatic leaf disease detection is an essential research topic as it may prove benefits in monitoring large fields of crops, and thus automatically detects symptoms of the disease as soon as they appear on plant leaves. The term disease is usually used only for the destruction of live plants. This paper provides various methods used to study of leaf disease detection using image processing. The methods studies are for increasing throughput and reduction subjects arising from human experts in detecting the leaf disease [1].digital image processing is a technique used for enhancement of the image. To improve agricultural products automatic detection of symptoms is beneficial

Structure and variability in the corona of the ultrafast rotator LO Peg

Low-mass ultrafast rotators show the typical signatures of magnetic activity and are known to produce flares, probably as a result of magnetic reconnection. As a consequence, the coronae of these stars exhibit very large X-ray luminosities and high plasma temperatures, as well as a pronounced inverse FIP effect. To probe the relationship between the coronal properties with a spectral type of ultra-fast rotators with rotation period P < 1d, we analyse the K3 rapid-rotator LO Peg observed with XMM-Newton and compare it with other low-mass rapid rotators of spectral types G9-M1. We investigate the temporal evolution of coronal properties like the temperatures, emission measures, abundances, densities and the morphology of the involved coronal structures. We find two distinguishable levels of activity in the XMM-Newton observation of LO~Peg, which shows significant X-ray variability both in phase and amplitude, implying the presence of an evolving active region on the surface. The X-ray flux varies by 28%, possibly due to rotational modulation. During our observation, a large X-ray flare with a peak X-ray luminosity of 2E30 erg/s and an energy of 7.3E33 erg was observed. At the flare onset we obtain clear signatures for the occurrence of the Neupert effect. The flare plasma also shows an enhancement of iron by a factor of 2 during the rise and peak phase of the flare. Our modeling analysis suggests that the scale size of the flaring X-ray plasma is smaller than 0.5 R_star. Further, the flare loop length appears to be smaller than the pressure scale height of the flaring plasma. Our studies show that the X-ray properties of the LO~Peg are very similar to those of other low-mass ultrafast rotators, i.e., the X-ray luminosity is very close to saturation, its coronal abundances follow a trend of increasing abundance with increasing first ionisation potential, the so-called inverse FIP effect.Comment: 11 pages, 15 figures and 4 tables. Accepted for publication by Astronomy and Astrophysic

MOSQUITO LARVICIDAL EFFICACY OF THE ACETONE LEAF EXTRACT OF SOLANUM TRILOBATUM AGAINST CULEX QUINQUEFASCIATUS AND AEDES AEGYPTI

Objective: The main objective of our study is to control the vector-borne disease. It is one among the major disease burden in developing countries. There are lots of researches carried out using the various plant extracts against larvicidal activities of the Culex quinquefasciatus and Aedes aegypti. The present investigation was aimed to investigate the phytochemical analysis and mosquito larvicidal activities of Solanum trilobatum in acetone extract against the second instar larvae of C. quinquefasciatus and A. aegypti. Methods: The leaf extract of S. trilobatum was subjected to phytochemical analysis and Gas Chromatography–Mass Spectrometry analysis. The mortality rates of the second instar larvae were recorded after 24, 48, 72, and 96 h of exposure. The lethal concentration (LC)50 and LC90 were determined followed by probit analysis.Results: The LC50 values for C. quinquefasciatus were found to be 265.69 ppm, 227.59 ppm, 212.42 ppm, and 189.47 ppm at various time intervals, and the LC90 values were 558.27 ppm, 504.92 ppm, 479.09 ppm, and 444.28 ppm. Similarly, LC50 values for A. aegypti were noticed at 301.09 ppm, 256.01 ppm, 209.75 ppm, and 167.44 ppm and the LC90 values were 582.34 ppm, 477.52 ppm, 419.40 ppm, and 371.84 ppm for the time interval of 24 h, 48 h, 72 h, and 96 h.Conclusion: The result of the current work revealed that the leaf extract of the S. trilobatum has the potential to be acted as an alternative for the controlling of the mosquitoes

Factors Affecting People’s Participation in Home Composting in Moratuwa and Kaduwela Municipalities in Western Province of Sri Lanka: A Comparative Study

Home composting is considered an effective method in solid waste management as composting reduces the amount of solid waste in the place of generation itself. However, many people are reluctant to adopt home composting for various reasons in Sri Lanka. This study examines the most significant factors influencing people's home composting based on Kaduwela and Moratuwa Municipalities (MC) of Western Province in Sri Lanka. Both Municipalities encourage composting programs in their areas. The study population was the total number of households in Moratuwa and Kaduwela Municipalities. For the sample, 2% (1808 households) of the population (households) from both Municipalities were selected randomly. The quantitative research method was used, and data were collected by using a structured close-ended questionnaire. Data were analyzed by using SPSS statistical software with descriptive and inferential statistics. Based on the analysis, the study confirmed that market opportunities for compost, social diffusion, access to the garden, higher family income level, local government intervention, and pro-environmental behavior significantly affect people's participation in home composting in both MCs. In addition to that, attitudes for gardening and general concern for the environment significantly affect Moratuwa MC, while health risks and attitudes for composting significantly affect Kaduwela MC for the people's participation in home composting. In comparatively, people's participation in home composting in Kaduwela MC relatively performs better than Moratuwa MC. Keywords: Home Composting, Municipal Solid Waste Management, Sri Lank