Improved dynamic geomagnetic rigidity cutoff modeling: testing predictive accuracy

. In the polar atmosphere, significant chemical and ionization changes occur during solar proton events (SPE). The access of solar protons to this region is limited by the dynamically changing geomagnetic field. In this study we have used riometer absorption observations to investigate the accuracy of a model to predict Kp-dependent geomagnetic rigidity cutoffs, and hence the changing proton fluxes. The imaging riometer at Halley, Antarctica is ideally situated for such a study, as the rigidity cutoff sweeps back and forth across the instrument's field of view, providing a severe test of the rigidity cutoff model. Using observations from this riometer during five solar proton events, we have confirmed the basic accuracy of this rigidity model. However, we find that the model can be improved by setting a lower Kp limit (i.e., Kp=5 instead of 6) at which the rigidity modeling saturates. We also find that for L>4.5 the apparent L-shell of the beam moves equatorwards. In addition, the Sodankyla Ion and Neutral Chemistry model is used to determine an empirical relationship between integral proton precipitation fluxes and nighttime ionosphere riometer absorption, in order to allow consideration of winter time SPEs. We find that during the nighttime the proton flux energy threshold is lowered to include protons with energies of >5 MeV in comparison with >10 MeV for the daytime empirical relationships. In addition, we provide an indication of the southern and northern geographic regions inside which SPEs play a role in modifying the neutral chemistry of the stratosphere and mesosphere

The concentration and biomagnification of trace metals and metalloids across four trophic levels in a marine food web

To be able to assess progress towards “Good Environmental Status” adopted across European Member States, and by the United Kingdom through its 3-stage Marine Strategy, contaminant concentrations and their biological effects need to be assessed in environmental samples by comparison to assessment criteria. This study examines the variability of concentrations (inter- and intra- species variation) of three priority heavy metals (Hg, Cd and Pb) and six additional trace metals and metalloids (As, Ni, Se, Zn, Cu and Cr) in twenty-three species across four trophic levels from different locations around Scotland. Trophic magnification factors (TMFs) were calculated using two methods for metals/metalloids possessing a significant trophic relationship (Hg, Cd, Cu, Ni and Zn) to refine and improve the application of TMFs to assess and predict biomagnification risk of metals/metalloids to biota in the environment. It was concluded that a reasonable balance in sample numbers of lower- versus higher-trophic level organisms is highly recommended when calculating TMFs and appropriate species selection is vital to ensure TMFs accurately represent the selected ecosystem

Terrain Park Injuries

Background: This study examined demographics, injury pattern, and hospital outcome in patients injured in winter resort terrain parks.Methods: The study included patients >12 years of age who presented to a regional trauma center with an acute injury sustained at a winter resort. Emergency department (ED) research assistants collected patient injury and helmet use information using a prospectively designed questionnaire. ED and hospital data were obtained from trauma registry and hospital records.Results: Seventy-two patients were injured in a terrain park, and 263 patients were injured on non-terrain park slopes. Patients injured in terrain parks were more likely to be male [68/72 (94%) vs. 176/263 (67%), p<0.0001], younger in age [23 ± 7 vs. 36 ± 17, p<0.0001], live locally [47/72 (65%) vs. 124/263 (47%), p=0.006], use a snowboard [50/72 (69%) vs. 91/263 (35%), p<0.0001], hold a season pass [46/66 (70%) vs. 98/253 (39%), p<0.0001], and sustain an upper extremity injury [29/72 (40%) vs. 52/263 (20%), p<0.001] when compared to patients injured on non-terrain park slopes. There were no differences between the groups in terms of EMS transport to hospital, helmet use, admission rate, hospital length of stay, and patients requiring specialty consultation in the ED.Conclusions: Patients injured in terrain parks represent a unique demographic within winter resort patrons. Injury severity appears to be similar to those patients injured on non-terrain park slopes.[West J Emerg Med. 2009;10(4):257-262.

The concentration and biomagnification of PCBs and PBDEs across four trophic levels in a marine food web.

Contracting Parties to the OSPAR Convention for the Protection of the Maine Environment of the North-East Atlantic are required to undertake monitoring and assessment of both inorganic and organic contaminants. There is a requirement to assess contaminants across different trophic levels on an ecosystem-specific basis. However, this is currently constrained by the availability of relevant samples to cover the full range of trophic levels. This study investigates the variability (inter- and intra-species variation) of the concentrations and distributions of thirty-two polychlorinated biphenyl (PCB) congeners and nine polybrominated diphenyl ether (PBDE) congeners in twenty-six species covering four trophic levels from different geographic locations around Scotland. Trophic magnification factors (TMFs) were calculated using a traditional method and a balanced method for both the ICES-7 PCBs and BDE47, to refine and improve the application of TMFs to assess and predict biomagnification risk to biota in the marine environment. There were clear differences in congener percentage distribution between sample categories and species, with differences influenced by physiological processes and eco-biological parameters. Trophic magnification was found to occur for the ICES-7 PCBs and BDE47 using the traditional method, with the highest degree of trophic magnification reported for CB52. An unbalanced dataset was found to influence the calculated TMF and in some cases, the overall conclusion of the trophic transfer of PCB and PBDE congeners. The balanced method is highly recommended for calculating TMFs to ensure that the TMF is a true indication of the biomagnification potential, particularly when conducting regional comparisons for which sampling requirements are difficult to achieve

Rapid improvement of cognitive maps in the awake state

Post-navigation awake quiescence, relative to task engagement, benefits the accuracy of a new “cognitive map”. This effect is hypothesized to reflect awake quiescence, like sleep, being conducive to the consolidation and integration of new spatial memories. Sleep has been shown to improve cognitive map accuracy over time. It remained unknown whether awake quiescence can induce similar time-related improvements in new cognitive maps, or whether it simply counteracts their decay. We examined this question via two experiments. In Experiment 1, using an established cognitive mapping paradigm, we reveal that map accuracy for a virtual town was significantly better in people whose memory was probed after 10 min of post-navigation awake quiescence or ongoing cognitive engagement, relative to those whose memory was probed shortly after initial navigation. In Experiment 2, using a newly developed cognitive mapping task that involved a more complex and real-life virtual town, we again found that map accuracy was superior in those whose memory was probed after 10 min of awake quiescence than those who were tested soon after navigation. These findings indicate that actual improvements in human memories are not restricted to sleep. Thus, contrary to conventional wisdom and theories, the passage of (day)time need not always result in forgetting

Nano-thermal imaging of the stratum corneum and its potential use for understanding of the mechanism of skin penetration enhancer

Nano-thermal analysis (nano-TA) is a localised thermal technique which maps a surface in terms of thermal transitions by combining atomic force microscopy with the use of thermal probes, allowing a spatial resolution of sub–100 nm. In this communication, we describe the application of a localised nano-TA approach, transition temperature microscopy (TTM), to investigate the thermotropic properties of porcine stratum corneum (PSC) as a function of depth and the influence of penetration enhancer on the nano-thermal properties of PSC. The investigations were conducted on PSC removed using tape strips. The transition temperature of PSC recorded at ∼220 °C was ascribed to protein denaturation/degradation. A decrease in the transition temperature was observed with an increase of skin depth. ‘Transition depression’ was observed when PSC was treated with propylene glycol, suggesting its water extraction effect on SC protein and a drop in the biomechanical properties of the SC. TTM has the potential to be extended to on in situ investigations of various penetration enhancers

Development and biological evaluation of Iinkjet printed drug coatings on intravascular stent

Inkjet–printing technology was used to apply biodegradable and biocompatible polymeric coatings of poly(D, L lactide) with the antiproliferative drugs simvastatin (SMV) and paclitaxel (PCX) on coronary metal stents. A piezoelectric dispenser applied coating patterns of very fine droplets (300 xL) and ink jetting was optimized to develop uniform, accurate and reproducible coatings of high yields on the stent strut. The drug loaded polymeric coatings were assed by scanning electron microscopy (SEM), atomic force microscopy (AFM) and transition thermal microscopy (TTM) where a phase separation was observed for SMV/PLA layers while PCX showed a uniform distribution within the polymer layers. Cytocompatibility studies of PLA coatings showed excellent cell adhesion with no decrease of cell viability and proliferation. In vivo stent implantation studies showed significant intra stent restenosis (ISR) for PXC/PLA and PLA plain coatings similar to marketed Presillion (bare metal) and Cypher (drug eluting) stents. The investigation of several cytokine levels after seven days of stent deployment showed no inflammatory response and hence no in vivo cytotoxicity related to PLA coatings. Inkjet printing can be employed as a robust coating technology for the development of drug eluting stents compared to the current conventional approaches

Energetic outer radiation belt electron precipitation during recurrent solar activity

Transmissions from three U.S. VLF (very low frequency) transmitters were received at Churchill, Canada, during an event study in May to November, 2007. This period spans four cycles of recurrent geomagnetic activity spaced similar to 27 days apart, with daily Sigma Kp reaching similar to 30 at the peaks of the disturbances. The difference in the amplitude of the signals received during the day and during the night varied systematically with geomagnetic activity, and was used here as a proxy for ionization changes caused by energetic electron precipitation. For the most intense of the recurrent geomagnetic storms there was evidence of electron precipitation from 3 300 keV and similar to 1 MeV trapped electrons, and also consistent with the daily average ULF (ultralow frequency) Pc1-2 power (L = 3.9) from Lucky Lake, Canada, which was elevated during the similar to 1 MeV electron precipitation period. This suggests that Pc1-2 waves may play a role in outer radiation belt loss processes during this interval. We show that the > 300 keV trapped electron flux from POES is a reasonable proxy for electron precipitation during recurrent high-speed solar wind streams, although it did not describe all of the variability that occurred. While energetic electron precipitation can be described through a proxy such as Kp or Dst, careful incorporation of time delays for different electron energies must be included. Dst was found to be the most accurate proxy for electron precipitation during the weak recurrent-activity period studied

Comparable rest-related promotion of spatial memory consolidation in younger and older adults

Flexible spatial navigation depends on cognitive mapping, a function that declines with increasing age. In young adults, a brief period of postnavigation rest promotes the consolidation and integration of spatial memories into accurate cognitive maps. We examined (1) whether rest promotes spatial memory consolidation and integration in older adults; and (2) whether the magnitude of the rest benefit changes with increasing age. Young and older adults learned a route through a virtual environment, followed by a 10-minute delay comprising either wakeful rest or a perceptual task, and a subsequent cognitive mapping task, requiring the pointing to landmarks from different locations. Pointing accuracy was lower in the older than younger adults. However, there was a comparable rest-related enhancement in pointing accuracy in the 2 age groups. Together our findings suggest that (1) the age-related decline in cognitive mapping cannot be explained by increased consolidation interference in older adults; and (2) as we grow older, rest continues to support the consolidation and integration of spatial memories

Semantic and generative models for lossy text compression

The apparent divergence between the research paradigms of text and image compression has led us to consider the potential for applying methods developed for one domain to the other. This paper examines the idea of "lossy" text compression, which transmits an approximation to the input text rather than the text itself. In image coding, lossy techniques have proven to yield compression factors that are vastly superior to those of the best lossless schemes, and we show that this a also the case for text. Two different methods are described here, one inspired by the use of fractals in image compression. They can be combined into an extremely effective technique that provides much better compression than the present state of the art and yet preserves a reasonable degree of match between the original and received text. The major challenge for lossy text compression is identified as the reliable evaluation of the quality of this match