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

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

Strong interrelationship between anomalous electric-field induced lattice strain along non-polar direction and domain reorientation in pseudorhombohedral piezoelectric ceramic BiScO3-PbTiO3

The lattice strain and domain switching behaviour was investigated as a function of cyclic field and grain orientation for a pseudorhombohedral composition of the high Curie point piezoelectric system xBiScO3 - (1-x)PbTiO3 (x = 0.40) by in-situ electric field diffraction technique with high energy synchrotron x-rays. Along the field direction, the system exhibts five time large strain along 100 as compared to the 111 direction. A one-to-one correspondence between the 200 lattice strain and the 111 domain switching suggests a strong correlation between the two phenomena.Comment: 11 pages, 7 figure

Catalytic Philanthropy In India

Catalytic Philanthropy is still in its infancy in India. Despite this, there are a surprising number of exemplary cases where Indian philanthropists are creating large-scale social change far beyond the resources invested. This report highlights these practices as well as the key issues that need to be addressed to accelerate its evolution

A STUDY ON INSTRUCTIONAL SUPERVISION BY PRINCIPALS IN TYPE 1C AND TYPE 2 SCHOOLS IN SRI LANKA

The main purpose of this study was to examine how principals’ engage in instructional supervision in Type 1C and Type 2 school in Sri Lanka. Three research questions were used to guide the study to a rational conclusion. Mixed Method was adopted in the study in order to triangulate data. Both questionnaire and semi structured interview schedules &nbsp;were used to obtain relevant data from 150 teachers, 10 principals and 10 sectional heads in 10 selected Type 1C and Type 2 &nbsp;schools using the simple random sampling techniques. Tables, percentages and graphs were used to analyze quantitative data and the qualitative data was analyzed by using thematic analysis and answer the research questions. The findings revealed that all the principals in the type 1C and Type 2 schools have positive perception about the role of instructional supervision and have formed an instructional supervisory team including the principal. However, the study revealed that the majority of principals in the type 1C and Type 2 schools do not engage in role of instructional supervision due to the major challenge of having engage in general administration roles than the instructional roles. The study further revealed that the existing internal supervisory team engage in instructional supervision role rarely and do not conduct post observational discussions which facilitate teachers to identify their strength and the areas that need further improvement. It is, therefore, recommended that, the principals need to carry out an adequate instructional supervision of teachers so as to improve their teaching skills and professional development. &nbsp

X-ray emission from the super-Earth host GJ 1214

Stellar activity can produce large amounts of high-energy radiation, which is absorbed by the planetary atmosphere leading to irradiation-driven mass-loss. We present the detection and an investigation of high-energy emission in a transiting super-Earth host system, GJ 1214, based on an XMM-Newton observation. We derive an X-ray luminosity LX=7.4E25 erg/s and a corresponding activity level of log(LX/Lbol)~ -5.3. Further, we determine a coronal temperature of about -3.5 MK, which is typical for coronal emission of moderately active low-mass stars. We estimate that GJ 1214 b evaporates at a rate of 1.3E10 g/s and has lost a total of ~2-5.6 MEarth.Comment: 5 pages, 3 figures, published in APJ

Primary Education in India: A Case Study of Government- Run Primary Schools in Rudraram

In India, we have three different types of schools, namely schools that follow state syllabus, schools that follow central syllabus and schools that follow International curriculum.  Hence, at any class level, we end up with students who have different levels of academic knowledge.  Coming to the rural villages, students who come from economically backward classes are obliged to opt for Government run schools due to their financial constraints.  The Government run schools teach in vernacular medium.  The present paper deals with the limitations of Government run schools in terms of performance when compared to Central Board schools and International curriculum schools.   For the purpose of present case study, the Mandal Parishad Primary school and Zilla Parishad Primary school in Rudraram, Patancheru Mandal in Andhra Pradesh State are considered.  The students in Zilla and Mandal Parishad Primary schools are basically from a weak economic background.  Students of these schools are beleaguered with linguistic, social, and financial problems.  Teachers who teach in these Parishad Primary schools should keep these facts in mind while teaching the students.    These Parishad Primary schools need teachers who not only can teach the subject to the students but also who are aware of the problems that students face in their daily lives so that the teachers can motivate them to excel and exceed in academics.  The present study deals with various factors that influence the performance of students in Zilla and Mandal Parishad Primary schools.  The study is carried out with the aim to call attention to the issues that hinder the progress of students.  These concerns can be identified and addressed by proper channels so that the Parishad Primary School students can emerge as competent individuals on par with students from schools run by Central Government and private sector.  The paper expounds that the society also has a major role to play in the improvement of Zilla Parishad Primary schools.  Instead of depending upon the Government alone for financial aid, society should come forward to improve rural education as these students are a part of future India. Keywords: Zilla Parishad Primary school, Mandal Parishad Primary school, rural education and Primary school education

ASSESSMENT OF α- AMYLASE INHIBITORY ACTION OF SOME EDIBLE PLANT SOURCES

Diabetes mellitus is one of the major causes for various manifestations of diseases and clinical complications. Plants are good sources of medicinal compounds and some are traditionally used to control Diabetes mellitus. In this study, the anti-diabetic potential of some edible plants was assessed by α-amylase inhibition assay. Among the studied plants, the extracts of Amaranthus dubius and Alternanthera sessilis were found to possess better inhibition potential against α-amylase enzyme. Acarbose and metformin used as standards for reference showed 67% and 48% inhibition efficiency respectively at a concentration of 250 µg/mL and 500 µg/mL. The results of the study ascertain the use of plants in the control of Diabetes mellitus. The inhibitory action of α-amylase mediated through the synergistic action of the phytoconstituents in the plants, lowers the glycemic level, reducing the risks associated with a sudden increase in blood sugar. The results of the study demonstrate the successful use of in vitro models in screening the plant sources for anti-diabetic activity.Â