The long term effects of sports concussion on retired Australian football players: a study using Transranial Magnetic Stimulation

This study investigated corticomotor excitability and inhibition, cognitive functioning, and fine motor dexterity in retired elite and amateur Australian football (AF) players who had sustained concussions during their playing careers. Forty male AF players who played at the elite level (n=20; mean age 49.7±5.7 years) or amateur level (n=20; mean age 48.4±6.9 years), and had sustained on average 3.2 concussions 21.9 years previously, were compared with 20 healthy age-matched male controls (mean age 47.56±6.85 years). All participants completed assessments of fine dexterity, visuomotor reaction time, spatial working memory (SWM), and associative learning (AL). Transcranial magnetic stimulation (TMS) was used to measure corticospinal excitability: stimulus-response (SR) curves and motor evoked potential (MEP) 125% of active motor threshold (aMT); and intracortical inhibition: cortical silent period (cSP), short-interval intracortical inhibition (SICI), and long-interval intracortical inhibition (LICI). Healthy participants performed better in dexterity (p=0.003), reaction (p=0.003), and movement time (p=0.037) than did both AF groups. Differences between AF groups were found in AL (p=0.027) and SWM (p=0.024). TMS measures revealed that both AF groups showed reduced cSP duration at 125% aMT (p>0.001) and differences in SR curves (p>0.001) than did healthy controls. Similarly, SICI (p=0.012) and LICI (p=0.009) were reduced in both AF groups compared with controls. Regression analyses revealed a significant contribution to differences in motor outcomes with the three measures of intracortical inhibition. The measures of inhibition differed, however, in terms of which performance measure they had a significant and unique predictive relationship with, reflecting the variety of participant concussion injuries. This study is the first to demonstrate differences in motor control and intracortical inhibition in AF players who had sustained concussions during their playing career two decades previously

Half a century of satellite remote sensing of sea-surface temperature

Sea-surface temperature (SST) was one of the first ocean variables to be studied from earth observation satellites. Pioneering images from infrared scanning radiometers revealed the complexity of the surface temperature fields, but these were derived from radiance measurements at orbital heights and included the effects of the intervening atmosphere. Corrections for the effects of the atmosphere to make quantitative estimates of the SST became possible when radiometers with multiple infrared channels were deployed in 1979. At the same time, imaging microwave radiometers with SST capabilities were also flown. Since then, SST has been derived from infrared and microwave radiometers on polar orbiting satellites and from infrared radiometers on geostationary spacecraft. As the performances of satellite radiometers and SST retrieval algorithms improved, accurate, global, high resolution, frequently sampled SST fields became fundamental to many research and operational activities. Here we provide an overview of the physics of the derivation of SST and the history of the development of satellite instruments over half a century. As demonstrated accuracies increased, they stimulated scientific research into the oceans, the coupled ocean-atmosphere system and the climate. We provide brief overviews of the development of some applications, including the feasibility of generating Climate Data Records. We summarize the important role of the Group for High Resolution SST (GHRSST) in providing a forum for scientists and operational practitioners to discuss problems and results, and to help coordinate activities world-wide, including alignment of data formatting and protocols and research. The challenges of burgeoning data volumes, data distribution and analysis have benefited from simultaneous progress in computing power, high capacity storage, and communications over the Internet, so we summarize the development and current capabilities of data archives. We conclude with an outlook of developments anticipated in the next decade or so

The accuracy of the AATSR sea surface temperatures in the Caribbean

The Along-Track Scanning Radiometer (ATSR) series of instruments provides the means to obtain accurate measurements of sea surface temperature (SST), with a target total uncertainty of ± 0.3 K, 1 σ. In this paper, we present validation results from 1 year of comparisons between 1 km resolution SSTs derived from the third instrument in the series, the Advanced ATSR (AATSR), and in situ measurements obtained during 2003 from the Marine-Atmospheric Emitted Radiance Interferometer (M-AERI) over the Caribbean. Our dataset consists of 99 cloud-free matchups, 25 of which are two-channel SST retrievals (daytime) and 74 three-channel SST retrievals (nighttime). Validation results for both dual- and nadir-view SSTs for these matchups are presented. We demonstrate that the dual–nadir SST measurement difference (D–N) can be used to classify matchups and attribute the likely cause of a particularly high D–N to outbreaks of Saharan dust. Under conditions of ‘normal’ D–N, the bias and standard deviation of the two- and three-channel dual-view retrievals is − 0.05 K and 0.26 K, and 0.02 K and 0.25 K, respectively. Dual-view SSTs obtained when the D–N is high over the Caribbean exhibit significant warm biases of 0.60 K and 0.32 K for two- and three-channel retrievals, respectively. Cool biases, with respect to the bias for ‘normal’ D–N, are observed in the nadir three-channel (N3) SSTs; for matchups with high D–N, the bias and standard deviation are − 0.16 K and 0.31 K, compared with 0.14 K and 0.24 K for ‘normal’ D–N. The distribution of the nadir two-channel retrievals is non-Gaussian and the apparent accuracy is comparatively poor, demonstrating clearly the advantages of using a sensor with dual-viewing capabilities to obtain a superior atmospheric correction, particularly when data from an additional short-wave infrared channel (e.g. at 3.7 μm) is not available

Future Development of the Operational AATSR LST Product

Future Development of the Operational AATSR LST Produc

An Accuracy Assessment of AATSR LST Data Using Theoretical and Empirical Methods

An Accuracy Assessment of AATSR LST Data Using Theoretical and Empirical Method

The geostationary tropospheric pollution explorer (GeoTROPE) mission: objectives, requirements and mission concept

International audienceOne of the major challenges facing atmospheric sciences is to assess, understand and quantify the impact of natural and an-thropogenic pollution on the quality of life on Earth on a local, regional and continental scale. It has become apparent that pollution originating from local/regional events can have serious effects on the composition of the lower atmosphere on a continental scale. However, to understand the effects of regional pollution on a continental scale there is a requirement to transcend traditional atmospheric spatial and temporal scales and attempt to monitor the entire atmosphere at the same time. In the troposphere the variability of chemical processes, of source strength and the dynamics induce important short term, i.e., sub-hourly, variations and significant horizontal and vertical variability of constituents and geophysical parameters relevant to a range of contemporary issues such as air quality. To study tropospheric composition, it is therefore required to link diurnal with seasonal and annual timescales, as well as local and regional with continental spatial scales, by performing sub-hourly measurements at appropriate horizontal and vertical resolution. Tropospheric observations from low-Earth orbit (LEO) platforms have already demonstrated the potential of detecting constituents relevant for air quality but they are limited, for example by the daily revisit time and local cloud cover statistics. The net result of this is that the troposphere is currently significantly under sampled. Measurements from Geostationary Orbit (GEO) offer the only practical approach to the observation of diurnal variation from space with the pertinent horizontal resolution. The Geostationary Tropospheric Pollution Explorer (GeoTROPE) is an attempt to determine tropospheric constituents with high temporal and spatial resolution. The paper will summarise the needs for geostationary observations of tropospheric composition and will give the mission objectives and the requirements

The accuracy of SST retrievals from AATSR: An initial assessment through geophysical validation against in situ radiometers, buoys and other SST data sets

The Advanced Along-Track Scanning Radiometer (AATSR) was launched on Envisat in March 2002. The AATSR instrument is designed to retrieve precise and accurate global sea surface temperature (SST) that, combined with the large data set collected from its predecessors, ATSR and ATSR-2, will provide a long term record of SST data that is greater than 15 years. This record can be used for independent monitoring and detection of climate change. The AATSR validation programme has successfully completed its initial phase. The programme involves validation of the AATSR derived SST values using in situ radiometers, in situ buoys and global SST fields from other data sets. The results of the initial programme presented here will demonstrate that the AATSR instrument is currently close to meeting its scientific objectives of determining global SST to an accuracy of 0.3 K (one sigma). For night time data, the analysis gives a warm bias of between +0.04 K (0.28 K) for buoys to +0.06 K (0.20 K) for radiometers, with slightly higher errors observed for day time data, showing warm biases of between +0.02 (0.39 K) for buoys to +0.11 K (0.33 K) for radiometers. They show that the ATSR series of instruments continues to be the world leader in delivering accurate space-based observations of SST, which is a key climate parameter. <br/