85 research outputs found
Infrared Spectroscopic Study of a Selection of AGB and Post-AGB Stars
We present here near-infrared spectroscopy in the H and K bands of a
selection of nearly 80 stars that belong to various AGB types, namely S type, M
type and SR type. This sample also includes 16 Post-AGB (PAGB) stars. From
these spectra, we seek correlations between the equivalent widths of some
important spectral signatures and the infrared colors that are indicative of
mass loss. Repeated spectroscopic observations were made on some PAGB stars to
look for spectral variations. We also analyse archival SPITZER mid-infrared
spectra on a few PAGB stars to identify spectral features due to PAH molecules
providing confirmation of the advanced stage of their evolution. Further, we
model the SEDs of the stars (compiled from archival data) and compare
circumstellar dust parameters and mass loss rates in different types.
Our near-infrared spectra show that in the case of M and S type stars, the
equivalent widths of the CO(3-0) band are moderately correlated with infrared
colors, suggesting a possible relationship with mass loss processes. A few PAGB
stars revealed short term variability in their spectra, indicating episodic
mass loss: the cooler stars showed in CO first overtone bands and the hotter
ones showed in HI Brackett lines. Our spectra on IRAS 19399+2312 suggest that
it is a transition object. From the SPITZER spectra, there seems to be a
dependence between the spectral type of the PAGB stars and the strength of the
PAH features. Modelling of SEDs showed among the M and PAGB stars that the
higher the mass loss rates, the higher the [K-12] colour in our sample.Comment: 14 pages; accepted in MNRAS, 200
Participation in Transition(s):Reconceiving Public Engagements in Energy Transitions as Co-Produced, Emergent and Diverse
This paper brings the transitions literature into conversation with constructivist Science and Technology Studies (STS) perspectives on participation for the first time. In doing so we put forward a conception of public and civil society engagement in sustainability transitions as co-produced, relational, and emergent. Through paying close attention to the ways in which the subjects, objects, and procedural formats of public engagement are constructed through the performance of participatory collectives, our approach offers a framework to open up to and symmetrically compare diverse and interconnected forms of participation that make up wider socio-technical systems. We apply this framework in a comparative analysis of four diverse cases of civil society involvement in UK low carbon energy transitions. This highlights similarities and differences in how these distinct participatory collectives are orchestrated, mediated, and subject to exclusions, as well as their effects in producing particular visions of the issue at stake and implicit models of participation and ‘the public’. In conclusion we reflect on the value of this approach for opening up the politics of societal engagement in transitions, building systemic perspectives of interconnected ‘ecologies of participation’, and better accounting for the emergence, inherent uncertainties, and indeterminacies of all forms of participation in transitions
HD 11397 and HD 14282 - Two new barium stars?
We have performed a detailed abundance analysis of the content of s-process
elements of two dwarf stars with suspected overabundace of those elements. Such
stars belong to a special kinematic sample of the solar neighborhood, with
peculiar kinematics and different chemical abundances when compared to "normal"
disk stars. We aim to define if those stars can be identified as barium stars,
based on their s-process elements abundances, and their classification, i.e.,
if they share their chemical profile with strong or mild barium stars. We also
intend to shed light on the possible origins of the different kinds of barium
stars. Spectra have been taken by using the FEROS spectrograph at the 1.52m
telescope of ESO, La Silla. Abundances have been derived for 18 elements, by
matching the synthetic profile with the observed spectrum. We have found that
HD 11397 shows a mild enhancement for most of the s-process elements as well as
for some r-process elements. This star seems to share its abundance profile
with the mild Ba-stars. Although showing some slight chemical anomalies for Y,
Sr, Mo, and Pb, HD 14282 depicts a chemical pattern similar to the normal stars
with slight s-process enhancements.Comment: 11 pages, 5 figure
Limits to reconstructing paleotopography from thermochronometer data
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/95240/1/jgrf851.pd
African Americans, Gentrification, and Neoliberal Urbanization: the Case of Fort Greene, Brooklyn
This article examines the gentrification of Fort Greene, which is located in the western part of black Brooklyn, one of the largest contiguous black urban areas in the USA. Between the late 1960s and 2003, gentrification in Fort Greene followed the patterns discovered by scholars of black neighborhoods; the gentrifying agents were almost exclusively black and gentrification as a process was largely bottom-up because entities interested in the production of space were mostly not involved. Since 2003, this has changed. Whites have been moving to Fort Greene in large numbers and will soon represent the numerical majority. Public and private interventions in and around Fort Greene have created a new top-down version of gentrification, which is facilitating this white influx. Existing black residential and commercial tenants are replaced and displaced in the name of urban economic development
3D: diversity, dynamics, differential testing – a proposed pipeline for analysis of next-generation sequencing T cell repertoire data
Quantitative characterization of T-cell repertoire and biomarkers in kidney transplant rejection
The Gravina Sequence: Remnants of a Mid-Mesozoic oceanic arc in southern southeast Alaska
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