The subarcsecond mid-infrared view of local active galactic nuclei: III. Polar dust emission

Recent mid-infrared (MIR) interferometric observations showed in few active galactic nuclei (AGN) that the bulk of the infrared emission originates from the polar region above the putative torus, where only little dust should be present. Here, we investigate whether such strong polar dust emission is common in AGN. Out of 149 Seyferts in the MIR atlas of local AGN (Asmus et al.), 21 show extended MIR emission on single dish images. In 18 objects, the extended MIR emission aligns with the system axis position angle, established by [OIII], radio, polarisation and maser based position angle measurements. The relative amount of resolved MIR emission is at least 40 per cent and scales with the [OIV] fluxes implying a strong connection between the extended continuum and [OIV] emitters. These results together with the radio-quiet nature of the Seyferts support the scenario that the bulk of MIR emission is emitted by dust in the polar region and not by the torus, which would demand a new paradigm for the infrared emission structure in AGN. The current low detection rate of polar dust in the AGN of the MIR atlas is explained by the lack of sufficient high quality MIR data and the requirement for the orientation, NLR strength and distance of the AGN. The James-Webb Space Telescope will enable much deeper nuclear MIR studies with comparable angular resolution, allowing us to resolve the polar emission and surroundings in most of the nearby AGN.Comment: Accepted for publication in ApJ on Mar 08 (submitted Dec 22

Gender and Social Capital Mediated Technology Adoption

This study explores gender-differentiated benefits from the social capital buildup in technology uptake, and the decision-making patterns of men and women with respect to production, consumption and household task; and allocation of resources. The background research examined women’s role in developing social capital, and research developed a case study of the groundnut producing areas of Maharashtra in western India, and compared ‘with’ and ‘without’ technology situations, and ‘before’ and ‘after’ situations in relation to the package of groundnut production technology introduced in the region in 1987. The paper addresses three aspects: (1) social networks in technology adoption, (2) the gender-based activity pattern, and (3) build-up of social capital leading to improvements in the welfare of farmers and the farming community with a gender perspective. Available evidence suggests substantial differences in networks of men and women, particularly in composition. The evidence suggests that men belong to more formal networks reflecting their employment or occupation status, while women have more informal networks that are centered on family and kin. Findings show that women who are engaged in agriculture and allied activities develop bonding social capital characterized by strong bonds such as that found among family members or among members of an ethnic group. Men who are engaged in agriculture, on the other hand, develop bridging social capital characterized by weaker, less dense but more crosscutting ties such as with farmers, acquaintances, friends from different ethnic groups and friends of friends. Women’s employment opportunities significantly improved with the introduction of technology. Finally, the study concludes that while technology development and exchange can build upon social capital as a means of empowering women, much more needs to be learned about the approaches that foster build-up of social capital.

A survey of single ended tuned grid tuned plate class C power amplifiers

The analysis of tuned grid-tuned plate Class C power amplifiers has been treated by many authors in many ways. The methods differ in accuracy and in time required to obtain the end results. A survey of most important of these methods was taken up by the author of this thesis with an aim towards studying their accuracies, advantages and disadvantages. A general survey of this type of analysis has not been found in the literature. In this survey only the most important phases of the tuned grid-tuned plate single ended Class C power amplifiers are discussed. This survey has been divided into four main sections. Part I. In this section a general survey of the following methods of solution of Class C amplifiers has been made. (a) Exact Analysis. This is a graphical analysis based on the use of constant current curves. It was derived by I. E. Mouromtseff and H. N. Kosanowski in 1535. On the basis of this analysis, a method of obtaining contour diagrams of various quantities such as output power, plate dissipation etc., are also discussed. Following the discussion of contour diagrams, an analysis by W. L. Everitt is given. This analysis is more or less exact. It makes the use of transfer characteristics of tubes and is based on the assumption that the transfer characteristics are linear. (b) Approximate Analysis. Four approximate methods of solving Class C amplifier problems have been discussed in this part of the thesis. The first method is that of F. E. Terman. This analysis is based upon the total space current in the vacuum tubes, and has been applied to triode as well as the pentode tubes. At the end of this analysis an outline for the design of Class C amplifiers is given. This is followed by a discussion of an approximate analysis of W. G. Wagener. In the latter analysis, a simplified method is given for quickly computing with reasonable accuracy the performance of Class C amplifiers. The third analysis is that of E. H. Schulz which makes use of radio frequency charts. These charts consist of various quantities such as the ratios of various components of current etc., as a function of the operative angle of current flow. The fourth analysis covers a step by step procedure of Class C amplifier design. This analysis makes use of charts in which ratios of peak, plate current to d. c. plate current are given as a function of the ratios of fundamental plate current to d. c. plate current and also uses constant current curves. (c) Illustrative Computations. In order to illustrate the various methods of analysis, an actual Class C amplifier design, problem has been worked out using a particular tube. The accuracies of the various analysts are compared and their advantages and disadvantages are discussed. (d) Factors affecting operation of Class C amplifiers. Here, a brief discussion has been given about the requirements that should be fulfilled by the plate tank circuits. Also, an analysis of grid driving power is discussed and a brief resume is made of the methods of obtaining grid bias voltage in Class C amplifiers. Part II. This section covers modulation of Class C amplifiers. In the first part of this section, a general discussion of amplitude modulation is given and this is followed by a discussion of a particular method of plate modulation. The remaining portion of tills section is devoted to analysis and methods of grid, suppressor, cathode and screen grid modulation. Part III. Neutralization of interelectrode capacitance has an important bearing on the performance of Class C amplifiers, and is discussed in this section. Part IV. In this section some of the problems that are involved in operation of Class C amplifiers at high frequencies are discussed. One of the most important of these is the effect of transit time in operation of tubes at high frequencies. Also, the effects of interelectrode capacitance and lead inductance are considered --Introduction, pages 1-4

The Evaluation of Schools to College and Career (S2C) Readiness Program for Middle School Student

There is a lack of research on what it means to be college and career ready at the middle school level, and this creates confusion for students when they enter high school and must select courses that are aligned with their college and career goals. This study sought to understand how the Schools to College and Career (S2C) Readiness Program impacts middle school students at the charter school. In order to understand this impact, the study looked at how the S2C Readiness Program relates to students’ understanding and awareness of CCR at the school. Using a quantitative approach this study will sought to answer: What factors influence middle school students\u27 awareness of college and career options after completing the S2C Readiness Program? To answer the guiding question middle school students completed two surveys. Archival data was also collected and analyzed. The results from the student survey responses showed an increase in interest in different careers as student performance level (measured from MAP score) increased. Furthermore, as students completed the S2C Readiness Program, their understanding of basic skills and content knowledge also increased. The results did show an increase in engagement and interest in their S2C elective courses. Also, students responded with an understanding of what it means to be college and career ready as they completed the S2C Readiness Program. There was also an increase in students seeking to understand what it means to be college and career ready as students get older. The research did not support a positive link between S2C elective class choice and college and career awareness. Many students responded that they did not explore college and career interests in their S2C class or on their own and did not engage in projects related to college and careers in their S2C elective class. This study sought to understand this impact, the study looked at how the S2C Readiness Program impacted students’ understanding and awareness of CCR at the charter school. Knowing that many students do not have the skills and tools necessary to be college and career ready this study hoped to provide insight for improving the S2C Readiness Program at the charter school. This research provided recommendations for improving the S2C Readiness Program at the charter school as well as college and career education opportunities in middle schools in general. This dissertation concluded with recommendations for future research to support such initiatives from elementary to the high school level

Lipid peroxidation is essential for α-synuclein-induced cell death.

Parkinson's disease is the second most common neurodegenerative disease and its pathogenesis is closely associated with oxidative stress. Deposition of aggregated α-synuclein (α-Syn) occurs in familial and sporadic forms of Parkinson's disease. Here, we studied the effect of oligomeric α-Syn on one of the major markers of oxidative stress, lipid peroxidation, in primary co-cultures of neurons and astrocytes. We found that oligomeric but not monomeric α-Syn significantly increases the rate of production of reactive oxygen species, subsequently inducing lipid peroxidation in both neurons and astrocytes. Pre-incubation of cells with isotope-reinforced polyunsaturated fatty acids (D-PUFAs) completely prevented the effect of oligomeric α-Syn on lipid peroxidation. Inhibition of lipid peroxidation with D-PUFAs further protected cells from cell death induced by oligomeric α-Syn. Thus, lipid peroxidation induced by misfolding of α-Syn may play an important role in the cellular mechanism of neuronal cell loss in Parkinson's disease. We have found that aggregated α-synuclein-induced production of reactive oxygen species (ROS) that subsequently stimulates lipid peroxidation and cell death in neurons and astrocytes. Specific inhibition of lipid peroxidation by incubation with reinforced polyunsaturated fatty acids (D-PUFAs) completely prevented the effect of α-synuclein on lipid peroxidation and cell death

The subarcsecond mid-infrared view of local active galactic nuclei: II. The mid-infrared--X-ray correlation

We present an updated mid-infrared (MIR) versus X-ray correlation for the local active galactic nuclei (AGN) population based on the high angular resolution 12 and 18um continuum fluxes from the AGN subarcsecond MIR atlas and 2-10 keV and 14-195 keV data collected from the literature. We isolate a sample of 152 objects with reliable AGN nature and multi-epoch X-ray data and minimal MIR contribution from star formation. Although the sample is not homogeneous or complete, we show that our results are unlikely to be affected by biases. The MIR--X-ray correlation is nearly linear and within a factor of two independent of the AGN type and the wavebands used. The observed scatter is <0.4 dex. A possible flattening of the correlation slope at the highest luminosities probed (~ 10^45 erg/s) is indicated but not significant. Unobscured objects have, on average, an MIR--X-ray ratio that is only <= 0.15 dex higher than that of obscured objects. Objects with intermediate X-ray column densities (22 < log N_H < 23) actually show the highest MIR--X-ray ratio on average. Radio-loud objects show a higher mean MIR--X-ray ratio at low luminosities, while the ratio is lower than average at high luminosities. This may be explained by synchrotron emission from the jet contributing to the MIR at low-luminosities and additional X-ray emission at high luminosities. True Seyfert 2 candidates and double AGN do not show any deviation from the general behaviour. Finally, we show that the MIR--X-ray correlation can be used to verify the AGN nature of uncertain objects. Specifically, we give equations that allow to determine the intrinsic 2-10 keV luminosities and column densities for objects with complex X-ray properties to within 0.34 dex. These techniques are applied to the uncertain objects of the remaining AGN MIR atlas, demonstrating the usefulness of the MIR--X-ray correlation as an empirical tool.Comment: Accepted for publication in MNRAS, 40 pages, 25 figure

Insights on neutrino lensing

We discuss the gravitational lensing of neutrinos by astrophysical objects. Unlike photons, neutrinos can cross a stellar core; as a result, the lens quality improves. We also estimate the depletion of the neutrino flux after crossing a massive object and the signal amplification expected. While Uranians alone would benefit from this effect in the Sun, similar effects could be considered for binary systems.Comment: 15 pages, 4 figures, to be published in Phys. Lett.