4,570 research outputs found

    Comparison of medium frequency pulsed radar interferometer and correlation analysis winds, part 2

    Get PDF
    In order to test whether the chosen Doppler peaks represent localized scatters in motion, as opposed to some sort of integrated composite, an attempt was made to determine the change in position of single scatterers over a series of sequential records. A four-antenna system was employed which had 1 degree of freedom in phase. Due to limitations N-S linear transmission and E-W linear reception were used. The Doppler frequency peak selection criteria were that at least two of the four power spectra should have a local peak, and that normalized phase discrepancy, should be less than 0.3. The lack of success in tracking individual scatters seems to suggest a short lifetime. If this is the case, then the present experiment is not able to resolve the difference found between the correlation analysis true velocity and the interferometer value. On the other hand, it appears that the interferometer may be of some use in tracking waves

    Measurement of the horizontal velocity of wind perturbations in the middle atmosphere by spaced MF radar systems

    Get PDF
    Two remote receiving sites have been set up at a distance of approx 40 km from the main MF radar system. This allows measurement of upper atmosphere winds from 60-120 km (3 km resolution) at the corners of an approximately equilateral triangle of side approx 20 km. Some preliminary data are compared through cross correlation and cross spectral analysis in an attempt to determine the horizontal velocity of wind perturbations and/or the horizontal wavelength and phase velocity of gravity waves

    A threshold caloric test- results in normal subjects

    Get PDF
    Threshold caloric test on normal subjects - responses to hot and cold caloric stimulatio

    Cortical activity evoked by inoculation needle prick in infants up to one-year old

    Get PDF
    Inoculation is one of the first and most common experiences of procedural pain in infancy. However, little is known about how needle puncture pain is processed by the central nervous system in children. In this study, we describe for the first time the event-related activity in the infant brain during routine inoculation using electroencephalography. Fifteen healthy term-born infants aged 1 to 2 months (n = 12) or 12 months (n = 5) were studied in an outpatient clinic. Pain behavior was scored using the Modified Behavioral Pain Scale. A distinct inoculation event-related vertex potential, consisting of 2 late negative-positive complexes, was observable in single trials after needle contact with the skin. The amplitude of both negative-positive components was significantly greater in the 12-month group. Both inoculation event-related potential amplitude and behavioral pain scores increased with age but the 2 measures were not correlated with each other. These components are the first recordings of brain activity in response to real-life needle pain in infants up to a year old. They provide new evidence of postnatal nociceptive processing and, combined with more traditional behavioral pain scores, offer a potentially more sensitive measure for testing the efficacy of analgesic protocols in this age group

    Can the U.S. Get There from Here?

    Get PDF
    Climate change impacts in the United States are increasingly evident and come with steep economic and social costs. The frequency and intensity of extreme weather events has increased in recent years, bringing record-breaking heat, heavy precipitation, coastal flooding, severe droughts, and damaging wildfires.According to the National Oceanic and Atmospheric Administration (NOAA), weather-related damages in the United States were $60 billion in 2011, and are expected to be significantly greater in 2012.The mounting costs convey an unmistakable urgency to address climate change by reducing greenhouse gas emissions (GHGs). This report examines pathways for GHG reductions in the United States through actions taken at the federal and state levels without the need for new legislation from the U.S. Congress

    Data Processing Methodologies to Investigate the Association between Depositional Environments and Trace Fossil Occurrence

    Get PDF
    The transition from late Ediacaran to early Cambrian records important paleobiological and paleoecological changes. These are observed in the Fortunian diversification event and the Agronomic Revolution, which describe significant body plan diversification, increased behavioral complexity in trace fossils, and a shift from matgrounds to mixgrounds ecosystems. To provide a more thorough understanding of this dramatic transition, data mining techniques (i.e. visual and statistical analysis) are used to investigate the relationship between depositional environments and trace fossil occurrence. To facilitate analysis, an ichnological database has been designed and implemented using Microsoft Access. The creation of this database is important in that it provides a platform for data digitization and subsequent data mining, while also accounting for fundamental differences between trace fossils and body fossils. Current paleontology databases do not recognize this distinction, which stems from the fact that trace fossils represent organism behavior, while body fossils record the phylogenetic affinities of an organism. Analysis of the ichnologic data compiled is supported with additional datasets, with a large focus on utilizing detrital zircon to infer geodynamic settings and to provide validation of paleogeographic reconstruction models via visual provenance analysis. A more quantified version of detrital zircon provenance analysis by way of Multidimensional Scaling (MDS) was conducted; however, this study has shown that MDS is best utilized at a regional scale. In combining all supplementary datasets, paleogeographic reconstructions for the Ediacaran, Terreneuvian, and Cambrian Epoch 2 have been constructed. With an appropriate spatial and temporal context, visual analysis of ichnologic data displays a global distribution of trace fossils through this transition, implying the utilization of available ecospace and a lack of paleoclimatic restrictions. Statistical analysis in the form of Correspondence Analysis (CA) displays a clear lack of relationships between ichnogenera and depositional environments during the Ediacaran, suggesting trace fossils were facies-crossing prior to Phanerozoic-style ecosystems. CA produces markedly different results during the early Cambrian, displaying ichnogenera differentiation between depositional environments (i.e. increasing beta ichnodiversity) in the relationship between Oldhamia and deep marine depositional environments. These results lend support to the Agronomic Revolution, as microbial matgrounds were forced into increasingly stressful paleoenvironments (i.e., deep marine settings) during this paleoecological revolution

    Cortical pain responses in human infants

    Get PDF
    Despite the recent increase in our understanding of the development of pain processing, it is still not known whether premature infants are capable of processing pain at a cortical level. In this study, changes in cerebral oxygenation over the somatosensory cortex were measured in response to noxious stimulation using real-time near-infrared spectroscopy in 18 infants aged between 25 and 45 weeks postmenstrual age. The noxious stimuli were heel lances performed for routine blood sampling; no blood tests were performed solely for the purpose of the study. Noxious stimulation produced a clear cortical response, measured as an increase in total hemoglobin concentration [HbT] in the contralateral somatosensory cortex, from 25 weeks (mean Delta[HbT] = 7.74 mu mol/L; SE, 1.10). Cortical responses were significantly greater in awake compared with sleeping infants, with a mean difference of 6.63 mu mol/L [95% confidence interval (CI) limits: 2.35, 10.91 mu mol/L; mean age, 35.2 weeks]. In awake infants, the response in the contralateral somatosensory cortex increased with age ( regression coefficient, 0.698 mu mol/L/week; 95% CI limits: 0.132, 1.265 mu mol/L/week) and the latency decreased with age (regression coefficient, -0.9861 mu mol/L/week; 95% CI limits: -1.5361, -0.4361 mu mol/L/week; age range, 25-38 weeks). The response was modality specific because no response was detected after non-noxious stimulation of the heel, even when accompanied by reflex withdrawal of the foot. We conclude that noxious information is transmitted to the preterm infant cortex from 25 weeks, highlighting the potential for both higher-level pain processing and pain-induced plasticity in the human brain from a very early age
    • …
    corecore