35,682 research outputs found
Fifteen-foot diameter modular space station Kennedy Space Center launch site support definition (space station program Phase B extension definition)
This document defines the facilities, equipment, and operational plans required to support the MSS Program at KSC. Included is an analysis of KSC operations, a definition of flow plans, facility utilization and modifications, test plans and concepts, activation, and tradeoff studies. Existing GSE and facilities that have a potential utilization are identified, and new items are defined where possible. The study concludes that the existing facilities are suitable for use in the space station program without major modification from the Saturn-Apollo configuration
Photometric reverberation mapping of 3C120
We present the results of a five month monitoring campaign of the local
active galactic nuclei (AGN) 3C120. Observations with a median sampling of two
days were conducted with the robotic 15cm telescope VYSOS-6 located near Cerro
Armazones in Chile. Broad band (B,V) and narrow band (NB) filters were used in
order to measure fluxes of the AGN and the H_beta broad line region (BLR)
emission line. The NB flux is constituted by about 50% continuum and 50% H_beta
emission line. To disentangle line and continuum flux, a synthetic H_beta light
curve was created by subtracting a scaled V-band light curve from the NB light
curve. Here we show that the H_beta emission line responds to continuum
variations with a rest frame lag of 23.6 +/- 1.69 days. We estimate a virial
mass of the central black hole M_BH = 57 +/- 27 * 10^6 solar masses, by
combining the obtained lag with the velocity dispersion of a single
contemporaneous spectrum. Using the flux variation gradient (FVG) method, we
determined the host galaxy subtracted rest frame 5100A luminosity at the time
of our monitoring campaign with an uncertainty of 10% (L_AGN = 6.94 +/- 0.71*
10^43 ergs^-1). Compared with recent spectroscopic reverberation results, 3C120
shifts in the R_BLR - L_AGN diagram remarkably close to the theoretically
expected relation of R-L^0.5. Our results demonstrate the performance of
photometric AGN reverberation mapping, in particular for efficiently
determining the BLR size and the AGN luminosityComment: 11 pages, 11 figures, Published in Astronomy and Astrophysic
A new list of thorium and argon spectral lines in the visible
Aims. We present a new list of thorium and argon emission lines in the
visible obtained by analyzing high-resolution (R=110,000) spectra of a ThAr
hollow cathode lamp. The aim of this new line list is to allow significant
improvements in the quality of wavelength calibration for medium- to
high-resolution astronomical spectrographs. Methods. We use a series of ThAr
lamp exposures obtained with the HARPS instrument (High Accuracy
Radial-velocity Planet Searcher) to detect previously unknown lines, perform a
systematic search for blended lines and correct individual wavelengths by
determining the systematic offset of each line relative to the average
wavelength solution. Results. We give updated wavelengths for more than 8400
lines over the spectral range 3785-6915 A. The typical internal uncertainty on
the line positions is estimated to be ~10 m/s (3.3 parts in 10^8 or 0.18 mA),
which is a factor of 2-10 better than the widely used Los Alamos Atlas of the
Thorium Spectrum (Palmer & Engleman 1983). The absolute accuracy of the global
wavelength scale is the same as in the Los Alamos Atlas. Using this new line
list on HARPS ThAr spectra, we are able to obtain a global wavelength
calibration which is precise at the 20 cm/s level (6.7 parts in 10^10 or 0.0037
mA). Conclusions. Several research fields in astronomy requiring high-precision
wavelength calibration in the visible (e.g. radial velocity planet searches,
variability of fundamental constants) should benefit from using the new line
list.Comment: 7 pages, 6 figures, accepted for publication in A&
The Gravitomagnetic Influence on Gyroscopes and on the Lunar Orbit
Gravitomagnetism--a motional coupling of matter analogous to the Lorentz
force in electromagnetism--has observable consequences for any scenario
involving differing mass currents. Examples include gyroscopes located near a
rotating massive body, and the interaction of two orbiting bodies. In the
former case, the resulting precession of the gyroscope is often called ``frame
dragging,'' and is the principal measurement sought by the Gravity Probe-B
experiment. The latter case is realized in the earth-moon system, and the
effect has in fact been confirmed via lunar laser ranging (LLR) to
approximately 0.1% accuracy--better than the anticipated accuracy of the
Gravity-Probe-B result. This paper shows the connnection between these
seemingly disparate phenomena by employing the same gravitomagnetic term in the
equation of motion to obtain both gyroscopic precession and modification of the
lunar orbit. Since lunar ranging currently provides a part in a thousand fit to
the gravitomagnetic contributions to the lunar orbit, this feature of
post-Newtonian gravity is not adjustable to fit any anomalous result beyond the
0.1% level from Gravity Probe-B without disturbing the existing fit of theory
to the 36 years of LLR data.Comment: 4 pages; accepted for publication in Physical Review Letter
Collection and rejuvenation of rare/scarce plants for the nursey stock industry.
End of Project ReportThe main objectives of this project were:
• Location of scarce/rare or new plants of high garden merit with tolerance to disease and
pests
• Rejuvenation.
• Conservation of rejuvenated plants in the original gardens from which they were
collected, at the Kinsealy Research Centre and in other selected locations.
• Evaluation of the collection for a variety of uses – foliage, patio etc. over a range of
different conditions and locations.
• Plant identification.
• Commercialisation of these plants by the trade to extend their range of plants.European
Union Structural Funds (EASSF
N-methylation of a bactericidal compound as a resistance mechanism in Mycobacterium tuberculosis
The rising incidence of antimicrobial resistance (AMR) makes it imperative to understand the underlying mechanisms. Mycobacterium tuberculosis (Mtb) is the single leading cause of death from a bacterial pathogen and estimated to be the leading cause of death from AMR. A pyrido-benzimidazole, 14, was reported to have potent bactericidal activity against Mtb. Here, we isolated multiple Mtb clones resistant to 14. Each had mutations in the putative DNA-binding and dimerization domains of rv2887, a gene encoding a transcriptional repressor of the MarR family. The mutations in Rv2887 led to markedly increased expression of rv0560c. We characterized Rv0560c as an S-adenosyl-L-methionine-dependent methyltransferase that N-methylates 14, abolishing its mycobactericidal activity. An Mtb strain lacking rv0560c became resistant to 14 by mutating decaprenylphosphoryl-beta-d-ribose 2-oxidase (DprE1), an essential enzyme in arabinogalactan synthesis; 14 proved to be a nanomolar inhibitor of DprE1, and methylation of 14 by Rv0560c abrogated this activity. Thus, 14 joins a growing list of DprE1 inhibitors that are potently mycobactericidal. Bacterial methylation of an antibacterial agent, 14, catalyzed by Rv0560c of Mtb, is a previously unreported mechanism of AMR
Using Case-Based Learning to Facilitate Clinical Reasoning Across Practice Courses in an Occupational Therapy Curriculum
Although occupational therapy educators have historically used cases as a means to prepare students for clinical practice, there is little evidence that this instructional method actually facilitates clinical reasoning. This convergent, parallel mixed methods study examined how the use of varied case formats, built on the tenets of case-based learning, facilitated specific components of clinical reasoning, and explored how the cases contributed to readiness for professional practice. Case formats included text, video, role-playing, simulated patients, and a client. Case-based learning activities included application of models and frames of reference, conducting assessments, planning and implementing interventions, clinical documentation, and identification of reasoning used. All cases included the opportunity for instructors to provide direct and appropriate feedback, and facilitation of student reflection on their performance. The Self-Assessment of Clinical Reflection and Reasoning (SACRR) was used for quantitative data analysis and detected statistically significant changes in the use of theory and frames of reference to inform practice and in student reasoning about interventions, following case-based learning. Student surveys allowed for pragmatic qualitative analysis, and identified the themes of self-awareness, confidence, and developing competence related to readiness for fieldwork and clinical practice. Student preferences for case format and benefits of varied types of cases were identified. Case-based learning used different case formats, and contributed to the occupational therapy student transition from a clinical reasoning novice to an advanced beginner. Knowledge of this process is useful to occupational therapy educators in structuring case-based learning activities to influencing reasoning
Quantum Chessboards in the Deuterium Molecular Ion
We present a new algorithm for vibrational control in deuterium molecules
that is feasible with current experimental technology. A pump mechanism is used
to create a coherent superposition of the D2+ vibrations. A short, intense
infrared control pulse is applied after a chosen delay time to create selective
interferences. A `chessboard' pattern of states can be realized in which a set
of even- or odd-numbered vibrational states can be selectively annihilated or
enhanced. A technique is proposed for experimental realization and observation
of this effect using 5 fs pulses of 790 nm radiation, with intermediate
intensity (5e13 W/cm2)Comment: 12 pages, 5 figure
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