4,435 research outputs found
Space Shuttle 2 advanced space transportation system, volume 2
To determine the best configuration from all candidate configurations, it was necessary first to calculate minimum system weights and performance. To optimize the design, it is necessary to vary configuration-specific variables such as total system weight, thrust-to-weight ratios, burn durations, total thrust available, and mass fraction for the system. Optimizing each of these variables at the same time is technically unfeasible and not necessarily mathematically possible. However, discrete sets of data can be generated which will eliminate many candidate configurations. From the most promising remaining designs, a final configuration can be selected. Included are the three most important designs considered: one which closely approximates the design criteria set forth in a Marshall Space Flight Center study of the Shuttle 2; the configuration used in the initial proposal; and the final configuration. A listing by cell of the formulas used to generate the aforementioned data is included for reference
Space Shuttle 2 Advanced Space Transportation System. Volume 1: Executive Summary
An investigation into the feasibility of establishing a second generation space transportation system is summarized. Incorporating successful systems from the Space Shuttle and technological advances made since its conception, the second generation shuttle was designed to be a lower-cost, reliable system which would guarantee access to space well into the next century. A fully reusable, all-liquid propellant booster/orbiter combination using parallel burn was selected as the base configuration. Vehicle characteristics were determined from NASA ground rules and optimization evaluations. The launch profile was constructed from particulars of the vehicle design and known orbital requirements. A stability and control analysis was performed for the landing phase of the orbiter's flight. Finally, a preliminary safety analysis was performed to indicate possible failure modes and consequences
WSPEC: A waveguide filter-bank focal plane array spectrometer for millimeter wave astronomy and cosmology
Imaging and spectroscopy at (sub-)millimeter wavelengths are key frontiers in
astronomy and cosmology. Large area spectral surveys with moderate spectral
resolution (R=50-200) will be used to characterize large scale structure and
star formation through intensity mapping surveys in emission lines such as the
CO rotational transitions. Such surveys will also be used to study the SZ
effect, and will detect the emission lines and continuum spectrum of individual
objects. WSPEC is an instrument proposed to target these science goals. It is a
channelizing spectrometer realized in rectangular waveguide, fabricated using
conventional high-precision metal machining. Each spectrometer is coupled to
free space with a machined feed horn, and the devices are tiled into a 2D array
to fill the focal plane of the telescope. The detectors will be aluminum
Lumped-Element Kinetic Inductance Detectors (LEKIDs). To target the CO lines
and SZ effect, we will have bands at 135-175 GHz and 190-250 GHz, each
Nyquist-sampled at R~200 resolution. Here we discuss the instrument concept and
design, and successful initial testing of a WR10 (i.e. 90 GHz) prototype
spectrometer. We recently tested a WR5 (180 GHz) prototype to verify that the
concept works at higher frequencies, and also designed a resonant backshort
structure that may further increase the optical efficiency. We are making
progress towards integrating a spectrometer with a LEKID array and deploying a
prototype device to a telescope for first light.Comment: 7 pages, 4 figures, submitted to Journal of Low Temperature Physic
The metric tide: report of the independent review of the role of metrics in research assessment and management
This report presents the findings and recommendations of the Independent Review of the Role of Metrics in Research Assessment and Management. The review was chaired by Professor James Wilsdon, supported by an independent and multidisciplinary group of experts in scientometrics, research funding, research policy, publishing, university management and administration.
This review has gone beyond earlier studies to take a deeper look at potential uses and limitations of research metrics and indicators. It has explored the use of metrics across different disciplines, and assessed their potential contribution to the development of research excellence and impact. It has analysed their role in processes of research assessment, including the next cycle of the Research Excellence Framework (REF). It has considered the changing ways in which universities are using quantitative indicators in their management systems, and the growing power of league tables and rankings. And it has considered the negative or unintended effects of metrics on various aspects of research culture.
The report starts by tracing the history of metrics in research management and assessment, in the UK and internationally. It looks at the applicability of metrics within different research cultures, compares the peer review system with metric-based alternatives, and considers what balance might be struck between the two. It charts the development of research management systems within institutions, and examines the effects of the growing use of quantitative indicators on different aspects of research culture, including performance management, equality, diversity, interdisciplinarity, and the ‘gaming’ of assessment systems. The review looks at how different funders are using quantitative indicators, and considers their potential role in research and innovation policy. Finally, it examines the role that metrics played in REF2014, and outlines scenarios for their contribution to future exercises
Differential motif enrichment analysis of paired ChIP-seq experiments
Motif enrichment analysis of transcription factor ChIP-seq data can help identify transcription factors that cooperate or compete. Previously, little attention has been given to comparative motif enrichment analysis of pairs of ChIP-seq experiments, where the binding of the same transcription factor is assayed under different conditions. Such comparative analysis could potentially identify the distinct regulatory partners/competitors of the assayed transcription factor under different conditions or at different stages of development
Characterizing the Cool KOIs. VI. H- and K-band Spectra of Kepler M Dwarf Planet-Candidate Hosts
We present H- and K-band spectra for late-type Kepler Objects of Interest
(the "Cool KOIs"): low-mass stars with transiting-planet candidates discovered
by NASA's Kepler Mission that are listed on the NASA Exoplanet Archive. We
acquired spectra of 103 Cool KOIs and used the indices and calibrations of
Rojas-Ayala et al. to determine their spectral types, stellar effective
temperatures and metallicities, significantly augmenting previously published
values. We interpolate our measured effective temperatures and metallicities
onto evolutionary isochrones to determine stellar masses, radii, luminosities
and distances, assuming the stars have settled onto the main-sequence. As a
choice of isochrones, we use a new suite of Dartmouth predictions that reliably
include mid-to-late M dwarf stars. We identify five M4V stars: KOI-961
(confirmed as Kepler 42), KOI-2704, KOI-2842, KOI-4290, and the secondary
component to visual binary KOI-1725, which we call KOI-1725 B. We also identify
a peculiar star, KOI-3497, which has a Na and Ca lines consistent with a dwarf
star but CO lines consistent with a giant. Visible-wavelength adaptive optics
imaging reveals two objects within a 1 arc second diameter; however, the
objects' colors are peculiar. The spectra and properties presented in this
paper serve as a resource for prioritizing follow-up observations and planet
validation efforts for the Cool KOIs, and are all available for download online
using the "data behind the figure" feature.Comment: Accepted for publication in the Astrophysical Journal Supplement
Series (ApJS). Data and table are available in the sourc
Characterizing the Cool KOIs II. The M Dwarf KOI-254 and its Hot Jupiter
We report the confirmation and characterization of a transiting gas giant
planet orbiting the M dwarf KOI-254 every 2.455239 days, which was originally
discovered by the Kepler mission. We use radial velocity measurements, adaptive
optics imaging and near infrared spectroscopy to confirm the planetary nature
of the transit events. KOI-254b is the first hot Jupiter discovered around an
M-type dwarf star. We also present a new model-independent method of using
broadband photometry to estimate the mass and metallicity of an M dwarf without
relying on a direct distance measurement. Included in this methodology is a new
photometric metallicity calibration based on J-K colors. We use this technique
to measure the physical properties of KOI-254 and its planet. We measure a
planet mass of Mp = 0.505 Mjup, radius Rp = 0.96 Rjup and semimajor axis a =
0.03 AU, based on our measured stellar mass Mstar = 0.59 Msun and radius Rstar
= 0.55 Rsun. We also find that the host star is metal-rich, which is consistent
with the sample of M-type stars known to harbor giant planets.Comment: AJ accepted (in press
Making Open Data Work for Civic Advocacy
The value of data in supporting citizen participation in processes of place-making and community building is widely recognised. While the open data movement now permits citizens to acquire governmental data relating to their communities, little to no effort is made to ensure that these datasets are accessible and interpretable by non-professionals. Through a series of community engagements spanning an 18-month period, we co-designed Data:In Place, an open source web tool which supports citizens in accessing, interpreting and making sense of open data. Leveraging visual map-based querying, citizens can access official statistics about their community, interrogate the data, and map their own data sources to create data visualisations. Reflecting on the participatory design process and the designed technology, we provide a framing to make open data work for civic advocacy
Characterization the Cool KOIs. II. The M Dwarf KOI-254 and its Hot Jupiter
We report the confirmation and characterization of a transiting gas giant planet orbiting the M dwarf KOI-254 every 2.455239 days, which was originally discovered by the Kepler mission. We use radial velocity measurements, adaptive optics imaging, and near-infrared spectroscopy to confirm the planetary nature of the transit events. KOI-254 b is the first hot Jupiter discovered around an M-type dwarf star. We also present a new model-independent method of using broadband photometry to estimate the mass and metallicity of an M dwarf without relying on a direct distance measurement. Included in this methodology is a new photometric metallicity calibration based on J – K colors. We use this technique to measure the physical properties of KOI-254 and its planet. We measure a planet mass of M_P = 0.505 M_(Jup), radius R_P = 0.96 R_(Jup), and semimajor axis a = 0.030 AU, based on our measured stellar mass M_* = 0.59 M_☉ and radius R_* = 0.55 R_☉. We also find that the host star is metal-rich, which is consistent with the sample of M-type stars known to harbor giant planets
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Production of ent-kaurene from lignocellulosic hydrolysate in Rhodosporidium toruloides.
BACKGROUND:Rhodosporidium toruloides has emerged as a promising host for the production of bioproducts from lignocellulose, in part due to its ability to grow on lignocellulosic feedstocks, tolerate growth inhibitors, and co-utilize sugars and lignin-derived monomers. Ent-kaurene derivatives have a diverse range of potential applications from therapeutics to novel resin-based materials. RESULTS:The Design, Build, Test, and Learn (DBTL) approach was employed to engineer production of the non-native diterpene ent-kaurene in R. toruloides. Following expression of kaurene synthase (KS) in R. toruloides in the first DBTL cycle, a key limitation appeared to be the availability of the diterpene precursor, geranylgeranyl diphosphate (GGPP). Further DBTL cycles were carried out to select an optimal GGPP synthase and to balance its expression with KS, requiring two of the strongest promoters in R. toruloides, ANT (adenine nucleotide translocase) and TEF1 (translational elongation factor 1) to drive expression of the KS from Gibberella fujikuroi and a mutant version of an FPP synthase from Gallus gallus that produces GGPP. Scale-up of cultivation in a 2 L bioreactor using a corn stover hydrolysate resulted in an ent-kaurene titer of 1.4 g/L. CONCLUSION:This study builds upon previous work demonstrating the potential of R. toruloides as a robust and versatile host for the production of both mono- and sesquiterpenes, and is the first demonstration of the production of a non-native diterpene in this organism
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