3,036 research outputs found
Reimagining Icarus: Ethics, Law and Policy Considerations for Commercial Human Spaceflight
Commercial human spaceflight presents an area for engaging novel human activity and objectives, to include space exploration, entertainment, transportation and extraterrestrial resource acquisition. The inherent dangers and lack of scientific and medical certainty involved however raise interrelated questions of ethics, bioethics, law and public policy. This is particularly the case with spaceflight participant (SFP) screening, selection, and commercial human spaceflight activities where regulations are currently silent or lacking. In the absence of established law, ethics can play an important role by informing industry standards, policies and best practices. Understanding the fundamental ethical values at stake in the application of new technologies and societal opportunities therefore is a significant step in establishing a practical, moral and sustainable framework for human expansion into space. As the frequency and reliability of private human spaceflight activities advances, spaceflight is likely to take on the legal and ethical vestiges of common carriers, with distinct passenger rights and higher standards of care attributed to the launch operator as a common carrier. This chapter raises some of the complex issues and challenges that face the private spaceflight industry and that merit collaborative discussion across disciplines and the global space transportation community going forward
Site Location Modeling and Prehistoric Rock Shelter Selection on the Upper Cumberland Plateau of Tennessee
Using data collected from 2 archaeological surveys of the Upper Cumberland Plateau (UCP), Pogue Creek Gorge and East Obey, a site location model was developed for prehistoric rock shelter occupation in the region. Further, the UCP model was used to explore factors related to differential site selection of rock shelters. Different from traditional approaches such as those that use (aspatial) logistic regression, the UCP model was developed using spatial logistic regression. However, models were also generated using other regression-based approaches in an effort to demonstrate the need for a spatial approach to archaeological site location modeling. Based on the UCP model, proximity to the vegetation zones of Southern Red Oak and Hickory were the most influential factors in prehistoric site selection of rock shelters on the UCP
Review of \u3ci\u3eThe Chosen Folks: Jews on the Frontiers of Texas\u3c/i\u3e by Bryan Edward Stone
Bryan Stone\u27s The Chosen Folks deserves widespread appeal. Those interested in Jewish studies, Texas history, and immigration will certainly find it a useful analysis. What\u27s more, those concerned with the frontier-where Jewish, Texan, immigrant, and other identities intertwine, influence, and define each other-will especially benefit. Stone aptly applies the modern reconceptualization of the frontier to describe the experiences of Jews- the quintessential frontierspeople -in Texas, a quintessential frontier.
Throughout the book Stone uses the frontier to organize and interpret the Texas Jewish experience. For example, the Republic of Texas\u27s location on a geographic frontier allowed Jews to develop an interior frontier wherein they could express or hide their Jewishness in accord with their circumstances. Furthermore, the geographic frontier enhanced Jews\u27 sense of being both insiders and outsiders in the newly formed state. Living great distances from centers of Jewish life, they identified with the dominant Anglo culture. Their Jewish heritage, however, distinguished them to some extent from the Anglo majority
Bioaccumulation surveillance in Milford Haven Waterway
Biomonitoring of contaminants (metals, organotins, PAHs, PCBs) was
carried out along the Milford Haven Waterway (MHW) and at a reference site in the
Tywi Estuary during 2007-2008. The species used as bioindicators encompass a
variety of uptake routes - Fucus vesiculosus (dissolved contaminants); Littorina
littorea (grazer); Mytilus edulis and Cerastoderma edule (suspension feeders); and
Nereis diversicolor (omnivore which often reflects contaminants in sediment).
Differences in feeding strategy and habitat preference have subtle implications for
bioaccumulation trends though, with few exceptions, contaminant body burdens in
Milford Haven (MH) were higher than those at the Tywi reference site, reflecting
inputs.
Elevated concentrations of metals were occasionally observed at individual MH sites,
whilst As and Se (molluscs and seaweed) were, for much of MHW, consistently at the
higher end of the UK range. However, for the majority of metals, distributions in MH
biota were not exceptional by UK standards. Several metal-species combinations
indicated increases in bioavailability at upstream sites, which may reflect the
influence of geogenic or other land-based sources – perhaps enhanced by lower
salinity (greater proportions of more bioavailable forms).
TBT levels in MH mussels were below OSPAR toxicity thresholds and in the Tywi
were close to zero. Phenyltins were not accumulated appreciably in Mytilus, whereas
some Nereis populations may have been subjected to localized (historical) sources.
PAHs in Nereis tended to be evenly distributed across most sites, but with somewhat
higher values at Dale for acenaphthene, fluoranthene, pyrene, benzo(a)anthracene and
chrysene; naphthalenes tended to be enriched further upstream in the mid-upper
Haven (a pattern seen in mussels for most PAHs). Whilst concentrations in MH
mussels were mostly above reference site and OSPAR backgrounds, it is unlikely that
ecotoxicological guidelines would be exceeded.
PCBs in mussels were between upper and lower OSPAR guidelines and were unusual
in their distribution in that highest levels occurred at the mouth of MH.
Condition indices (CI) of bivalves (mussels and cockles) were highest at the Tywi
reference site and at the seaward end of MH, decreasing upstream along the
Waterway. There were a number of significant (negative) relationships between CI
and body burdens and multivariate analysis indicated that a combination of
contaminants could influence the pattern in condition (and sub-lethal responses such
as MT and TOSC) across sites. Cause and effect needs to be tested more rigorously in
future assessments
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Cross-platform validation of notional baseline architecture models of naval electric ship power systems
To support efforts in assessing the relative merit of alternative power system architectures for future naval combatants, the Electric Ship Research and Development Consortium (ESRDC) has developed notional baseline models for each of the primary candidate architectures currently considered, medium-voltage DC (MVDC), conventional 60 Hz medium-voltage (MVAC), and high-frequency medium-voltage (HFAC). Initial efforts have focused on the development of a consistent set of component models, of which the system models can be comprised, and the basic definition of the system models. The broader objectives of the consortium, however, go beyond the definition of the baseline models. The focus is on the process by which the models are implemented in software and validated, the process by which the performance of the disparate system models are objectively and quantitatively assessed and compared, and, ultimately, the process by which the relative merits of the architectures may be assessed. This paper focuses specifically on cross-platform component validation.Center for Electromechanic
Intersex related gene expression profiles in clams Scrobicularia plana : molecular markers and environmental application
Intersex, the appearance of female characteristics in male gonads, has been identified in several aquatic species. It is a widespread phenomenon in populations of the bivalve, Scrobicularia plana, from the southwest coast of the U.K. Genes previously identified as differentially expressed (ferritin, testicular haploid expressed gene, THEG, proliferating cell nuclear antigen, PCNA; receptor activated protein kinase C, RACK; cytochrome B, CYB; and cytochrome c oxidase 1, COX1) in intersex clams relative to normal male clams, were selected for characterisation and an environmental survey of the Channel region. Transcripts were significantly differentially expressed at sites with varying intersex incidence and contaminant burdens. Significant correlations between specific gene expressions, key contaminants and sampling locations have been identified, though no single gene was associated with intersex incidence. The results highlight the difficulty in understanding the intersex phenomenon in molluscs where there is still a lack of knowledge on the control of normal reproduction
Pulsar Science with the Green Bank 43m Telescope
The 43m telescope at the NRAO site in Green Bank, WV has recently been
outfitted with a clone of the Green Bank Ultimate Pulsar Processing Instrument
(GUPPI \cite{Ransom:2009}) backend, making it very useful for a number of
pulsar related studies in frequency ranges 800-1600 MHz and 220-440 MHz. Some
of the recent science being done with it include: monitoring of the Crab
pulsar, a blind search for transient sources, pulsar searches of targets of
opportunity, and an all-sky mapping project. For the Crab monitoring project,
regular observations are searched for giant pulses (GPs), which are then
correlated with -ray photons from the \emph{Fermi} spacecraft. Data
from the all-sky mapping project are first run through a pipeline that does a
blind transient search, looking for single pulses over a DM range of 0-500
pc~cm. These projects are made possible by MIT Lincoln Labs.Comment: 2 pages, 1 figure, to appear in AIP Conference Proceedings of Pulsar
Conference 2010 "Radio Pulsars: a key to unlock the secrets of the Universe",
Sardinia, October 201
HI Clouds in the M81 Filament as Dark Matter Minihalos--A Phase-Space Mismatch
Cosmological galaxy formation models predict the existence of dark matter
minihalos surrounding galaxies and in filaments connecting groups of galaxies.
The more massive of these minihalos are predicted to host HI gas that should be
detectable by current radio telescopes such as the GBT. We observed the region
including the M81/M82 and NGC 2403 galaxy groups, searching for observational
evidence of an HI component associated with dark matter halos within the "M81
Filament", using the Robert C. Byrd Green Bank Telescope (GBT). The map covers
an 8.7 degree x 21.3 degree (480 kpc x 1.2 Mpc) region centered between the
M81/M82 and NGC 2403 galaxy groups. Our observations cover a wide velocity
range, from -890 to 1320 km/s, which spans much of the range predicted by
cosmological N-body simulations for dark matter minihalo velocities. Our search
is not complete in the velocity range -210 to 85 km/s, containing Galactic
emission and the HVC Complex A. For an HI cloud at the distance of M81, with a
size < 10 kpc, our average 5-sigma mass detection limit is 3.2 x 10^6 M_Sun,
for a linewidth of 20 km/s. We compare our observations to two large
cosmological N-body simulations and find that the simulation predicts a
significantly greater number of detectable minihalos than are found in our
observations, and that the simulated minihalos do not match the phase space of
observed HI clouds. These results place strong constraints on the HI gas that
can be associated with dark-matter halos. Our observations indicate that the
majority of extragalactic HI clouds with a mass greater than 10^6 M_Sun are
likely to be generated through tidal stripping caused by galaxy interactions.Comment: 15 pages, 7 figures. Accepted for publication in the AJ with minor
revision
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