Recent Editions

This semiannual bibliography of documentary editions recently published in the fields of American and British history, literature, and culture is generally restricted to scholarly first editions of English language works. In addition to the bibliographical references, Internet addresses are provided for the editorial project or the publisher

Recent Editions

This semiannual bibliography of documentary editions recently published in the fields of American and British history, literature, and culture is generally restricted to scholarly first editions of English language works. In addition to the bibliographical references, Internet addresses are provided for the editorial project or the publisher

Is the Bardeen-Petterson effect responsible for the warping and precession in NGC 4258?

Strong evidence for the presence of a warped Keplerian accretion disc in NGC4258 (M 106) has been inferred from the kinematics of water masers detected at sub-parsec scales. Assuming a power-law accretion disc and using constraints on the disc parameters derived from observational data, we have analyzed the relativistic Bardeen-Petterson effect driven by a Kerr black hole as the potential physical mechanism responsible for the disc warping. We found that the Bardeen-Petterson radius is comparable to or smaller than the inner radius of the maser disc (independent of the allowed value for the black hole spin parameter). Numerical simulations for a wide range of physical conditions have shown that the evolution of a misaligned disc due to the Bardeen-Petterson torques usually produces an inner flat disc and a warped transition region with a smooth gradient in the tilt and twist angles. Since this structure is similar to that seen in NGC 4258, we propose that the Bardeen-Petterson effect may be responsible for the disc warping in this galaxy. We estimated the time-scale necessary for the disc inside of the Bardeen-Petterson radius to align with the black hole's equator, as a function of the black hole spin. Our results show that the Bardeen-Petterson effect can align the disc within a few billion years in the case of NGC 4258. Finally, we show that if the observed curvature of the outer anomalous arms in the galactic disc of NGC 4258 is associated with the precession of its radio jet/counterjet, then the Bardeen-Petterson effect can provide the required precession period.Comment: 10 pages, 5 figures, 1 table, accepted for publication in The Monthly Notices of the Royal Astronomical Societ

The mass loss process in dwarf galaxies from 3D hydrodynamical simulations: the role of dark matter and starbursts

Theoretical $\Lambda$CDM cosmological models predict a much larger number of low mass dark matter haloes than has been observed in the Local Group of galaxies. One possible explanation is the increased difficulty of detecting these haloes if most of the visible matter is lost at early evolutionary phases through galactic winds. In this work we study the current models of triggering galactic winds in dwarf spheroidal galaxies (dSph) from supernovae, and study, based on 3D hydrodynamic numerical simulations, the correlation of the mass loss rates and important physical parameters as the dark matter halo mass and its radial profile, and the star formation rate. We find that the existence of winds is ubiquitous, independent on the gravitational potential. Our simulations revealed that the Rayleigh-Taylor Instability (RTI) may play a major role on pushing matter out of these systems, even for very massive haloes. The instability is responsible for 5 - 40% of the mass loss during the early evolution of the galaxy, being less relevant at $t > 200$Myrs. There is no significant difference in the mass loss rates obtained for the different dark matter profiles studied (NFW and logarithmic). We have also found a correlation between the mass loss rate and both the halo mass and the rate of supernovae, as already reported in previous works. Besides, the epoch in which most of the baryon galactic matter is removed from the galaxy varies depending on the SN rate and gravitational potential. The later, combined to the importance of the RTI in each model, may change our understanding about the chemical evolution of dwarf galaxies, as well as in the heavy element contamination of the intergalactic medium at high redshifts.Comment: MNRAS, accepte

Public Vocational School Teachers\u27 Experiences and Perceived Self-Efficacy in Working with Students with Disabilities in an Inclusive Environment: A Phenomenological Inquiry Study

Full inclusion of students with disabilities within the general education classroom has been a longstanding goal of many school districts within the United States. Many studies have been conducted to understand what attributes are needed for successful inclusion with the evidence pointing to the need for teachers to have a strong sense of instructional self-efficacy when working with students with disabilities. Copious research concerning teachers’ experiences with inclusive education has been conducted across typical public-school settings; however, scant information is known about inclusive education experiences of general education teachers employed in vocational high schools. The purpose of this transcendental phenomenological study was to describe the experiences that shape and/or affect the self-efficacy of vocational educators teaching students with disabilities in rural inclusive vocational classrooms. The research questions were framed so as to discover what individual, environmental, and prior experiences are be associated with general vocational education teachers’ sense of self-efficacy in teaching students with disabilities in a vocational educational inclusive classroom setting. Criterion-based sampling was used to recruit between 10-15, with a minimum of 10, faculty members from a rural medium-sized technical school in western Massachusetts. Using the Teacher Efficacy for Inclusive Practices scale, one-on-one interviews, and a focus group, the perceptions and experiences related to inclusion were collected, coded, and thematically analyzed using NVivo. From the data, four themes emerged: (a) successful inclusion, (b) prior experiences, (c) awareness and (d) school environment. Study findings may inform curriculum and best practices for teaching to inclusive vocational classrooms and guide professional development decisions regarding inclusive educational practices in vocational classrooms