6,394 research outputs found
Status of LIGO
LIGO construction has been completed. The three interferometers at the two LIGO observatory sites (Livingston, Louisiana and Hanford, Washington) have been operated successfully as power-recycled Michelson interferometers with Fabry-Perot arm cavities. Commissioning of the interferometers has progressed to operating them simultaneously in this final optical configuration. The initial coincidence operation between the observatory sites has provided a full test of the detector hardware and software subsystems, and full operation of the data acquisition and data analysis systems. The LIGO Laboratory and the LIGO Scientific Collaboration are working together to exploit the early series of interleaved engineering and science runs to commission the detector and data systems, to provide a detailed characterization of the detector and to produce the first scientific results from LIGO. The operation of LIGO is also coordinated with operation of the GEO 600 detector and the ALLEGRO resonant mass detector. The status of this early operation and data study will be presented
The Thirty Meter Telescope (TMT): An International Observatory
The Thirty Meter Telescope (TMT) will be the first truly global ground-based optical/infrared observatory. It will initiate the era of extremely large (30-meter class) telescopes with diffraction limited performance from its vantage point in the northern hemisphere on Mauna Kea, Hawaii, USA. The astronomy communities of India, Canada, China, Japan and the USA are shaping its science goals, suite of instrumentation and the system design of the TMT observatory. With large and open Nasmyth-focus platforms for generations of science instruments, TMT will have the versatility and flexibility for its envisioned 50 years of forefront astronomy. The TMT design employs the filled-aperture finely-segmented primary mirror technology pioneered with the W.M. Keck 10-meter telescopes. With TMTâs 492 segments optically phased, and by employing laser guide star assisted multi-conjugate adaptive optics, TMT will achieve the full diffraction limited performance of its 30-meter aperture, enabling unprecedented wide field imaging and multi-object spectroscopy. The TMT project is a global effort of its partners with all partners contributing to the design, technology development, construction and scientific use of the observatory. TMT will extend astronomy with extremely large telescopes to all of its global communities
Interview with Gary H. Sanders
Interview October 16, 1998, with Gary H. Sanders, then project manager for LIGO; currently (2010) project manager for the Thirty-Meter Telescope.
Recalls building cyclotron, Stuyvesant High School. Physics major, Columbia University (BA 1967): Mel Schwartz, Leon Lederman, Jack Steinberger, T. D. Lee; politically active. PhD, high-energy physics (MIT, 1971). Three years with Samuel C. C. Ting at DESY in Germany. Princeton postdoc with A. J. S. Smith. Brookhaven and Fermilab. Leaves for Los Alamos, 1978. To Brookhaven, 1984, kaon decay experiment.
Proposes neutrino experiment, Los Alamos. Meets Barry Barish, member DOE review committee. Discusses neutrino oscillation experiments. Involved with SSC [Superconducting Super Collider] in 1989 through Ting, who builds a detector for it. Troubles between Ting and Roy Schwitters, SSC director. Barish as co-leader of U.S. groups with Ting. Ting detector project falls through; Sanders and Barish pick it up. 1993, Congress cancels SSC. Barish returns to Caltech; Sanders to Los Alamos to GLAST [Gamma-ray Large Area Space Telescope]; investigates WWII human radiation experiments at Los Alamos.
Rochus (Robbie) Vogt removed as LIGO director, replaced by Barish (1994), who brings Sanders in as project manager. His first impressions of LIGO. Comments on Kip Thorne, Rainer Weiss, Vogt, and Ronald W. P. Drever. NSB review of LIGO, fall 1994. Many LIGO scientists left. Caltech as ideal LIGO venue.
Collaboration with foreign gravity-wave groups. Common data format. LIGO Scientific Collaboration. LIGO origins at Caltech in 1970s. Discusses need for openness in LIGO
Status of LIGO
LIGO construction has been completed. The three interferometers at the two LIGO observatory sites (Livingston, Louisiana and Hanford, Washington) have been operated successfully as power-recycled Michelson interferometers with Fabry-Perot arm cavities. Commissioning of the interferometers has progressed to operating them simultaneously in this final optical configuration. The initial coincidence operation between the observatory sites has provided a full test of the detector hardware and software subsystems, and full operation of the data acquisition and data analysis systems. The LIGO Laboratory and the LIGO Scientific Collaboration are working together to exploit the early series of interleaved engineering and science runs to commission the detector and data systems, to provide a detailed characterization of the detector and to produce the first scientific results from LIGO. The operation of LIGO is also coordinated with operation of the GEO 600 detector and the ALLEGRO resonant mass detector. The status of this early operation and data study will be presented
Excitonic effects on coherent phonon dynamics in single wall carbon nanotubes
We discuss how excitons can affect the generation of coherent radial
breathing modes in ultrafast spectroscopy of single wall carbon nanotubes.
Photoexcited excitons can be localized spatially and give rise to a spatially
distributed driving force in real space which involves many phonon wavevectors
of the exciton-phonon interaction. The equation of motion for the coherent
phonons is modeled phenomenologically by the Klein-Gordon equation, which we
solve for the oscillation amplitudes as a function of space and time. By
averaging the calculated amplitudes per nanotube length, we obtain
time-dependent coherent phonon amplitudes that resemble the homogeneous
oscillations that are observed in some pump-probe experiments. We interpret
this result to mean that the experiments are only able to see a spatial average
of coherent phonon oscillations over the wavelength of light in carbon
nanotubes and the microscopic details are averaged out. Our interpretation is
justified by calculating the time-dependent absorption spectra resulting from
the macroscopic atomic displacements induced by the coherent phonon
oscillations. The calculated coherent phonon spectra including excitonic
effects show the experimentally observed symmetric peaks at the nanotube
transition energies in contrast to the asymmetric peaks that would be obtained
if excitonic effects were not included.Comment: submitted to Phys. Rev. B on 7 May 2013, revised on 17 July and 13
August 2013, published 30 August 201
Continuous, 8-Paddock, and 16-Paddock Grazing at Two Stocking Rates With Different Breed Types
Last updated: 6/12/200
A Missense Mutation in Canine CLN6 in an Australian Shepherd with Neuronal Ceroid Lipofuscinosis
The childhood neuronal ceroid lipofuscinoses (NCLs) are inherited neurodegenerative diseases that are progressive and ultimately fatal. An Australian Shepherd that exhibited a progressive neurological disorder with signs similar to human NCL was evaluated. The cerebral cortex, cerebellum, and retina were found to contain massive accumulations of autofluorescent inclusions characteristic of the NCLs. Nucleotide sequence analysis of DNA from the affected dog identified a T to C variant (c.829T>C) in exon 7 of CLN6. Mutations in the human ortholog underlie a late-infantile form of NCL in humans. The T-to-C transition results in a tryptophan to arginine amino acid change in the predicted protein sequence. Tryptophans occur at homologous positions in the CLN6 proteins from all 13 other vertebrates evaluated. The c.829T>C transition is a strong candidate for the causative mutation in this NCL-affected dog. Dogs with this mutation could serve as a model for the analogous human disorder
Validation of cardiovascular magnetic resonance assessment of pericardial adipose tissue volume
© 2009 Nelson et al; licensee BioMed Central Ltd.Background Pericardial adipose tissue (PAT) has been shown to be an independent predictor of coronary artery disease. To date its assessment has been restricted to the use of surrogate echocardiographic indices such as measurement of epicardial fat thickness over the right ventricular free wall, which have limitations. Cardiovascular magnetic resonance (CMR) offers the potential to non-invasively assess total PAT, however like other imaging modalities, CMR has not yet been validated for this purpose. Thus, we sought to describe a novel technique for assessing total PAT with validation in an ovine model. Methods 11 merino sheep were studied. A standard clinical series of ventricular short axis CMR images (1.5T Siemens Sonata) were obtained during mechanical ventilation breath-holds. Beginning at the mitral annulus, consecutive end-diastolic ventricular images were used to determine the area and volume of epicardial, paracardial and pericardial adipose tissue. In addition adipose thickness was measured at the right ventricular free wall. Following euthanasia, the paracardial adipose tissue was removed from the ventricle and weighed to allow comparison with corresponding CMR measurements. Results There was a strong correlation between CMR-derived paracardial adipose tissue volume and ex vivo paracardial mass (R2 = 0.89, p < 0.001). In contrast, CMR measurements of corresponding RV free wall paracardial adipose thickness did not correlate with ex vivo paracardial mass (R2 = 0.003, p = 0.878). Conclusion In this ovine model, CMR-derived paracardial adipose tissue volume, but not the corresponding and conventional measure of paracardial adipose thickness over the RV free wall, accurately reflected paracardial adipose tissue mass. This study validates for the first time, the use of clinically utilised CMR sequences for the accurate and reproducible assessment of pericardial adiposity. Furthermore this non-invasive modality does not use ionising radiation and therefore is ideally suited for future studies of PAT and its role in cardiovascular risk prediction and disease in clinical practiceAdam J Nelson, Matthew I Worthley, Peter J Psaltis, Angelo Carbone, Benjamin K Dundon, Rae F Duncan, Cynthia Piantadosi, Dennis H Lau, Prashanthan Sanders, Gary A Wittert and Stephen G Worthle
Efficacious, effective, and embedded interventions: Implementation research in infectious disease control
Background: Research in infectious disease control is heavily skewed towards high end
technology; development of new drugs, vaccines and clinical interventions. Oft ignored, is the
evidence to inform the best strategies that ensure the embedding of interventions into health
systems and amongst populations. In this paper we undertake an analysis of the challenge in the
development of research for the sustainable implementation of disease control interventions.
Results: We highlight the fundamental differences between the research paradigms associated
with the development of technologies and interventions for disease control on the one hand and the research paradigms required for enhancing the sustainable uptake of those very same
interventions within the communities on the other. We provide a definition for implementation
research in an attempt to underscore its critical role and explore the multidisciplinary science
needed to address the challenges in disease control.
Conclusion: The greatest value for money in health research lies in the sustainable and effective implementation of already proven, efficacious solutions. The development of implementation research that can help provide some solutions on how this can be achieved is sorely needed
Pressure pain thresholds fluctuate with, but do not usefully predict, the clinical course of painful temporomandibular disorder
Central sensitization elicits pain hypersensitivity and is thought to be causally implicated in painful temporomandibular disorder (TMD). This causal inference is based on cross-sectional evidence that people with TMD have greater sensitivity than controls to noxious stimuli. We tested this inference in the OPPERA prospective cohort study of 3,258 adults with no lifetime history of TMD when enrolled (Visit 1). During five years of follow-up, one group labelled âpersistent TMD casesâ (n=72) developed first-onset TMD by Visit 2 that persisted â„6 months until Visit 3. Another group labelled âtransient TMD casesâ (n=75) developed first-onset TMD at Visit 2 which resolved by Visit 3. Randomly sampled âcontrolsâ (n=126) remained TMD-free throughout all three visits. At each visit, pressure pain thresholds (PPTs) were measured by algometry at 10 cranial and bodily sites. In persistent TMD cases, mean PPTs reduced 43 kPa (P<0.0001) between Visits 1 and 2 and thereafter did not change significantly. In transient TMD cases, mean PPTs reduced 41 kPa (P<0.001) between Visits 1 and 2, and then increased 20 kPa (P<0.001) by Visit 3. These patterns were similar after excluding cranial sites symptomatic for TMD. Importantly, Visit 1 PPTs had no clinically useful prognostic value in predicting first-onset TMD (odds ratio [OR] 1.07, P=0.15). Among first-onset cases, Visit 2 PPTs were modest predictors of persistent TMD (OR=1=.36, P=0.002). In this longitudinal study, PPTs reduced when TMD developed then rebounded when TMD resolved. However, pre-morbid PPTs poorly predicted TMD incidence, countering the hypothesis that they signify mechanisms causing first-onset TMD
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