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OBJECTIVES/SPECIFIC AIMS: Our research hypothesis is that resting state fMRI (rsfMRI) data can be used to identify regions of the brain which are associated with cognitive decline in patients – thereby providing a tool by which to characterize AD progression in patients. METHODS/STUDY POPULATION: We used data from the Alzheimer’s Disease Neuroimaging Initiative (ADNI) to analyze Mini-Mental State Examination (MMSE) questionnaire scores from 14 patients diagnosed with AD at two measurement occasions. RsfMRI data was available at the first of these occasions for these patients. These rsfMRI data were summarized into 264 node-based graph theory measures of clustering coefficient and eigenvector centrality. To address our research hypothesis, we modeled changes in patient MMSE scores over time as a function of these rsfMRI data, controlling for relevant confounding factors. This model accounted for the high-dimensionality of our predictor data, the longitudinal nature of the outcome, and our desire to identify a subset of regions in the brain most associated with the MMSE outcome. RESULTS/ANTICIPATED RESULTS: The use of either the clustering coefficient or eigenvector centrality rsfMRI predictors in modeling MMSE scores for patients over time resulted in the identification of different subsets of brain regions associated with cognitive decline. This suggests that these predictors capture different information on patient propensity for cognitive decline. Further work is warranted to validate these results on a larger sample of ADNI patients. DISCUSSION/SIGNIFICANCE OF IMPACT: We conclude that different rsfMRI graph theory measures capture different aspects of cognitive function and decline in patients, which could be a future consideration in clinical practice.
This literature review aimed to identify the range of methods used in after action reviews (AARs) of public health emergencies and to develop appraisal tools to compare methodological reporting and validity standards.
A review of biomedical and gray literature identified key approaches from AAR methodological research, real-world AARs, and AAR reporting templates. We developed a 50-item tool to systematically document AAR methodological reporting and a linked 11-item summary tool to document validity. Both tools were used sequentially to appraise the literature included in this study.
This review included 24 highly diverse papers, reflecting the lack of a standardized approach. We observed significant divergence between the standards described in AAR and qualitative research literature, and real-world AAR practice. The lack of reporting of basic methods to ensure validity increases doubt about the methodological basis of an individual AAR and the validity of its conclusions.
The main limitations in current AAR methodology and reporting standards may be addressed through our 11 validity-enhancing recommendations. A minimum reporting standard for AARs could help ensure that findings are valid and clear for others to learn from. A registry of AARs, based on a common reporting structure, may further facilitate shared learning. (Disaster Med Public Health Preparedness. 2019;13:618-625)
During 1990, the Parkes radio telescope made a new, deep survey of the southern sky at 4850 MHz (the PMN Survey: see e.g. Griffith and Wright, 1993; Wright et al., 1994). The declination coverage of the survey was from δ = −87° to +10°. The flux limit of the survey was around 30 mJy, although dependent on declination. This survey increased the number of known, southern radio sources by a factor of about 6 to over 65,000.
The Molonglo Observatory Synthesis Telescope is equipped with a transient event monitoring system which operates during normal synthesis observations. The device is designed to respond to impulsive signals which occur within the passband (843.0 ± 1.5 MHz) with time scales between 0.001 ms and 800 ms. The multiple beam facility of the telescope provides some discrimination against local interference. An upper limit of 1.7 × 10−2 events s−1 sr−1 has been placed on celestial events with durations between 1 ms and 25 ms and energy density ≥ 10−28 J m−2 Hz−1. The monitoring system has been recently reconfigured to improve the recognition and rejection of impulsive signals of non-celestial origin.
We present an overview of the survey for radio emission from active stars that has been in progress for the last six years using the observatories at Fleurs, Molonglo, Parkes and Tidbinbilla. The role of complementary optical observations at the Anglo-Australian Observatory, Mount Burnett, Mount Stromlo and Siding Spring Observatories and Mount Tamborine are also outlined. We describe the different types of star that have been included in our survey and discuss some of the problems in making the radio observations.
A small astronomical observatory has been constructed on the edge of the Macquarie University campus at North Ryde in Sydney. It will be used primarily for photoelectric observations of variable stars. Further improvements to the present observing system are being planned and observations have already started on β Cepheids.
The single G8V active chromosphere star HD36705 (AB Dor) was observed at 8.4 GHz with the Parkes 64 m telescope during three observing sessions involving a total of 21 days in the interval 1985 December to 1986 February. Subsequent photometric observations were made of the star with the 0.25 m and 0.45 m telescopes of the Monash Observatory in 1986 March-April. Two strong radio flares, each lasting three days, were detected; they yielded peak radio powers of P8.4≈4×109 W Hz-1, comparable with the microwave power emitted by the RS CVn binaries. Significant circular polarization of 13% left-hand was measured on only one of the six active days. The 8.4 GHz flux density showed smooth variation over an interval of several hours, consistent with the flare source being partly occulted by the stellar disk as the star rotated. When all the radio data was phase-binned using the known rotation period of 0.514 day we found two radio maxima corresponding to radio sources at stellar longitudes ~180° apart. The subsequent photometric data showed intensity variations that were consistent with the starspots at the same approximate longitudes. We thus interpret our radio curve as showing the presence of comparatively small (<0.5 D*) radio sources in the corona above the star spots. The upper limit to source diameter gives a peak brightness temperature ≥2×l010 K, which can be achieved by gyro-synchrotron emission only if the source is optically thick and the electrons, with average energy ~ 2 MeV, have a hard energy spectrum. The observed radiation can be due only to very high harmonics of the gyro-frequency, leading to an estimate for the magnetic field strength of ~30G.
The Molonglo Observatory synthesis telescope has been used to obtain twelve observations of a 23′ arc field containing the active star AB Dor. On each occasion, an unresolved source close to the optical position of AB Dor was observed. The source exhibits day-to-day variations of flux density, with a mean value of ∼4 mJy. The identification of the source with the star and the variations in emission are discussed.
The design and scientific applications of a 96-channel filter spectrograph of 1 MHz resolution are presented. The spectrograph is currently under construction and will be installed on the Parkes telescope in 1987-1988. Its main scientific objective is dynamic spectral studies of decimetre- and metre-wavelength bursts from flare stars. However, it will also be used for performing large-scale pulsar surveys, and dynamic spectral observations of interplanetary scintillation of compact sources, interstellar scintillation of compact extragalactic sources, and interesting radio sources in general.
We show that plasma emission generated in the coronae of flare stars should be detectable at metre- and decimetre-wavelengths. We plan to search for fundamental and second-harmonic plasma radiation by observing in two harmonically related bands, 200 to 250 MHz and 400 to 500 MHz. With noise-adding to stabilize receiver gain, the sensitivity (3σ) of each channel of the spectrograph is ∼ 1.5 Jy for a 1-s integration. Previous studies have reported peak flux densities of up to ∼ 35 Jy and ∼ 12 Jy at 240 MHz and 410 MHz respectively for radio bursts from flare stars.
The physical properties and spatial distribution of 12 pulsars discovered with the Molonglo radio telescope have been discussed by Mills. Several more pulsars have been detected and details will be published when the measurements are complete. Parameters of a recently discovered pulsar, MP 0628, are given in Table I. All the Molonglo pulsars have been found by visual examination of chart records. The use of pulse lengthening circuits to improve the visibility of pulsars on slow charts, and the continuation of the observations over several hundred hours with the greatest available sensitivity have been factors contributing significantly to the success of the Molonglo pulsar search.
The Molonglo Observatory Synthesis Telescope is being used in a continuing program of observation of known Southern active stars. By May, 1987, a total of forty-one stars had been observed and 843 MHz quiescent emission, presumably associated with the star, had been detected in nine instances. The emission from five of these stars has shown marked variation on a time-scale > 1 day.
In its normal synthesis mode of operation, the Molonglo Observatory Synthesis Telescope (MOST) tracks a region of sky for a period of 12 hours with 64 real-time fan beams having high sensitivity at 843 MHz (Mills 1981). It thus provides an excellent opportunity to monitor the sky at the same time for transient radio events. During a 12 hour synthesis observation the fan beams rotate 180° on the field. Thus any sources producing occasional radio transients can be located by analysing the positions of the beams on which the events are recorded. Futhermore, by rejecting events which occur simultaneously on non-adjacent beams, local terrestrial sources of impulsive interference may be eliminated. This technique for recognizing extra-terrestrial sources was of considerable value in the first Molonglo pulsar search when only two beams were used.
We describe bright microwave events that were first detected with the Parkes 64-m telescope at 8.4 or 22 GHz from six active-chromosphere stars. In some flares spectral data were obtained over a large frequency range from simultaneous measurements with the Parkes reflector (8.4 or 22 GHz), the Tidbinbilla interferometer (8.4 and 2.29 GHz), the Fleurs synthesis telescope (1.42 GHz) and the Molonglo Observatory synthesis telescope (0.843 GHz). Data on circular polarization were obtained from the Parkes observations at 8.4 GHz.
The stars were in a wide variety of evolutionary states, ranging from a single pre-main-sequence star (HD 36705), two RS CVn binaries (HD 127535, HD 128171), an Algol (HD 132742) and two apparently single K giants (HD 32918 and HD 196818). Their high brightness temperatures, positive spectral indices and low polarization are consistent with optically thick gyrosynchrotron emission from mildly relativistic electrons with average energies 0.5 to 3 MeV gyrating in inhomogeneous magnetic fields of 5 to 100 G.
During 1990 we surveyed the southern sky using a multi-beam receiver at frequencies of 4850 and 843 MHz. The half-power beamwidths were 4 and 25 arcmin respectively. The finished surveys cover the declination range between +10 and −90 degrees declination, essentially complete in right ascension, an area of 7.30 steradians. Preliminary analysis of the 4850 MHz data indicates that we will achieve a five sigma flux density limit of about 30 mJy. We estimate that we will find between 80 000 and 90 000 new sources above this limit. This is a revised version of the paper presented at the Regional Meeting by the first four authors; the surveys now have been completed.
The binary flare star AT Mic has been observed with the VLA (5 GHz and 1.5 GHz) and, nearly simultaneously, with the MOST (0.843 GHz). There appears to be a slowly varying component of the radio intensity, with a flux density greater at 0.843 GHz than at higher frequencies. It is suggested that above 1 GHz the emission is possibly produced by incoherent gryosynchrotron radiation, whereas below 1 GHz a coherent mechanism predominates.
Known Southern flare stars and RSCVn-like variables are being observed with the Molonglo Observatory Synthesis Telescope in an attempt to detect quiescent (non-flaring) emission. Two flare stars out of 7 and one RSCVn out of 8 have been detected. Quiescent emission has not been observed previously from these sources at such a low frequency. All sources so far detected have mean flux densities below 10 mJy and in at least two of them the emission varies with a time scale of about one day.