Spread-F ionospheric irregularities and their relationship to stable auroral red arcs at magnetic mid-latitudes

The signature of the stable auroral red arc (SAR arc) as it appears on ionograms is described. The key features are a very significant increase in the amount of spread-F and a reduction in the maximum plasma density compared with regions just equatorward and poleward of the SAR arc Identification of the SAR arc signature is made by using complementary data from the global auroral imaging instrument on board the Dynamics Explorer-1 satellite. At sunspot minimum there is a positive correlation between the occurrence of spread-F on ionograms from Argentine Islands, Antarctica (65°S, 64°W; L = 2.3) and magnetic activity. In contrast, at sunspot maximum there is a weak negative correlation when the K magnetic index is less than 6. but a significant increase in spread-F occurrence at K ⩾ 6. Detailed study of ionograms shows that there are two distinct regions where considerable spread-F is observed. These are the region where SAR arcs occur and the poleward edge of the mid-latitude ionospheric trough. They are separated by a region associated with the trough minimum, where comparatively little spread-F is seen. It is suggested that the movement of these features to lower latitudes with increasing magnetic and solar activity can explain the lack of correspondence between variations of spread-F occurrence as a function of magnetic activity at sunspot maximum compared with that at sunspot minimum at Argentine Islands. read more

The effect of temperature on the growth of Candida saké isolated from the leaves of a subantarctic grass

During a survey of microfungi on the subantarctic island of South Georgia, large numbers of phylloplane yeasts were isolated in late spring from leaves of a tussock grass. The dominant yeast was identified asCandida saké, this being the first record for the Antarctic region. Isolates in liquid culture had a temperature optimum for growth of 20–25°C. It was capable of assimilation of a range of simple carbohydrates, similar to those found in leachates from new leaves of the tussock grass. The seasonal decline of yeasts on the phylloplane is discussed in terms of the availability of leachate and the growth of filamentous microfungi on new leaves.

Fasting metabolism in Antarctic fur seal (Arctocephalus gazella) pups

first_imgThe metabolism of 52–73-day old Antarcticfursealpups from Bird Island, South Georgia, was investigated during fasting periods of normal duration while their mothers were at sea foraging. Body mass decreased exponentially with pups losing 3.5–3.8% of body mass per day. Resting metabolic rate also decreased exponentially from 172–197 ml (O2)·min−1 at the beginning of the fast and scaled to Mb0.74 at 2.3 times the level predicted for adult terrestrial mammals of similar size. While there was no significant sex difference in RMR, female pups had significantly higher (F1,18=6.614, P<0.019) mass-specific RMR than male pups throughout the fasting period. Fasting FMR was also significantly (t15=2.37, P<0.035) greater in females (823 kJ·kg−1·d−1) than males (686 kJ·kg−1·d−1). Average protein turnover during the study period was 19.3 g·d−1 and contributed to 5.4% of total energy expenditure, indicating the adoption of a protein-sparing strategy with a reliance on primarily lipid catabolism for metabolic energy. This is supported by observed decreases in plasma BUN, U/C, glucose and triglyceride concentrations, and an increase in β-HBA concentration, indicating that Antarcticfursealspups adopt this strategy within 2–3 days of fasting. Mean RQ also decreased from 0.77 to 0.72 within 3 days of fasting, further supporting a rapid commencement of protein-sparing. However, RQ gradually increased thereafter to 0.77, suggesting a resumption of protein catabolism which was not substantiated by changes in plasma metabolites. Female pups had higher TBL (%) than males for any given mass, which is consistent with previous findings in this and other furseal species, and suggests sex differences in metabolic fuel use. The observed changes in plasma metabolites and protein turnover, however, do not support this.last_img read more

A window on West Antarctic crustal boundaries: the junction between the Antarctic Peninsula, the Filchner Block, and Weddell Sea oceanic lithosphere

first_imgA new airborne magnetic survey of the southeastern Antarctic Peninsula and adjacent Weddell Sea embayment (WSE) region suggests a continuity of geological structure between the eastern Antarctic Peninsula and the attenuated continental crust of the Filchner Block. This has implications for the reconstructed position of the Ellsworth-Whitmore Mountains block in Gondwana, which is currently uncertain. Palaeomagnetic data indicate that it has migrated from a Palaeozoic position between South Africa and Coats Land to its current position as a microplate embedded in central West Antarctica. The most obvious route for migration is between the Antarctic Peninsula and the Weddell Sea embayment. Evidence that geological structures are continuous across the boundary places constraints on the timing and pathway of migration. Magnetic textures suggest the presence of shallow features extending from the Beaumont Glacier Zone (BGZ) in the west for at least 200 kin into the Weddell Sea embayment. These data suggest that the Eastern Domain of the Antarctic Peninsula and the stretched continental crust of the Filchner Block share a common recent, probably post-Early Jurassic, history. However, examination of deep anomalies indicates differences in the magnetic characteristics of the two blocks. The boundary may mark either the edge of extended continental crust, or a discontinuity between two, once separated, blocks. This discontinuity, or pre-Late Jurassic Antarctic Peninsula terrane boundaries to the west, may have allowed the passage of the Ellsworth-Whitmore Mountains block to its present location.last_img read more

Intra-annual variability in the density of Antarctic krill (Euphausia superba) at South Georgia, 2002-2005: within-year variation provides a new framework for interpreting previous ‘annual’ estimates of krill density

first_imgUpward-looking acoustic Doppler current profilers (300 kHz) and echo sounders (125 kHz) were deployed on moorings on- and off-shelf to the northwest of South Georgia between 14 October 2002 and 29 December 2005 to measure density of Antarctic krill and environmental parameters continuously. A distinct seasonal pattern in krill density, recurring consistently over all three years, was detected. Krill densities in winter were predominantly low (mean = 18.7 g m(-2), SD = 24.3), but had risen substantially by summer in each year (mean = 89.5 g m(-2), SD = 64.2). A sinusoidal regression model (period = 52 weeks) with time as the independent variable explained 64% of the observed week-to-week variation. Estimates of krill density from moored instruments were not statistically different (P > 0.05) from estimates derived from standard ship-based krill surveys in adjacent time periods, suggesting that the point estimates from moored instruments were representative of krill density in a wider spatial context (ship surveys cover c. 100 x 100 km). Data from moored instruments were used to explore whether high-frequency temporal variation (i.e. within-year) could have led to the perceived between-year variation in krill density arising from previous summer surveys in the South Georgia western core box region between 1990 and 2005. Comparison of these ‘snap-shot’ ship survey estimates with the observed pattern of within-year variability showed that some of the apparent ‘year-to-year’ variation could simply be attributed to sampling on different dates of the year (e.g. November cf. February). However, there were some survey estimates that were significantly different (P < 0.01) from the regression-predicted within-year variation. Years that stand out for markedly low krill density (i.e. densities below the range expected due to intra-annual variation) were 1993/94, 1998/99 and 1999/2000. Moored instruments provide valuable data that could be important for ecosystem-based management at South Georgia because, for example, they will enable predator-prey functional responses to be explored there for the first time at appropriate temporal scales, and will enable hypotheses relating variation in krill abundance to physical oceanographic variability to be tested.last_img read more

Aspects of resilience of polar sea ice algae to changes in their environment

first_imgSea ice algae are primary producers of the ice-covered oceans in both polar regions. Changes in sea ice distribution are potentially altering exposure to photosynthetically active radiation (PAR) and ultraviolet-B (UV-B) wavelengths of light. Incubations using monospecific cultures of common species from the Ross Sea, Antarctic Peninsula and Arctic Ocean were carried out at ecologically relevant light levels during periods of 7 days to examine tolerance to conditions likely to be faced during sea ice thinning and melt. Algal responses were assessed using chlorophyll fluorescence techniques and superoxide dismutase (SOD) activity. Quantum yields of cultures incubated in the dark and at ambient light did not differ. At higher light levels, the Ross Sea and Arctic cultures showed no significant change in photosynthetic health. Cultures from the Antarctic Peninsula showed a significant decrease. Antarctic cultures showed no detectable changes in SOD activity. Arctic culture showed dynamic changes, initially increasing, then decreasing to the end of the study. The general lack of significant changes signals the need for further parameters to be assessed during such experiments. The coupling between measured parameters appeared to protect photosynthetic health, even though significant effects have been detected in other studies when subjected to PAR or UV-B alone.last_img read more

Contrasting effects of tropical cyclones on the annual survival of a pelagic seabird in the Indian Ocean

first_imgTropical cyclones are renowned for their destructive nature and are an important feature of marine and coastal tropical ecosystems. Over the last 40 years, their intensity, frequency and tracks have changed, partly in response to ocean warming, and future predictions indicate that these trends are likely to continue with potential consequences for human populations and coastal ecosystems. However, our understanding of how tropical cyclones currently affect marine biodiversity, and pelagic species in particular, is limited. For seabirds, the impacts of cyclones are known to be detrimental at breeding colonies, but impacts on the annual survival of pelagic adults and juveniles remain largely unexplored and no study has simultaneously explored the direct impacts of cyclones on different life-history stages across the annual life cycle. We used a 20-year data set on tropical cyclones in the Indian Ocean, tracking data from 122 Round Island petrels and long-term capture–mark–recapture data to explore the impacts of tropical cyclones on the survival of adult and juvenile (first year) petrels during both the breeding and migration periods. The tracking data showed that juvenile and adult Round Island petrels utilize the three cyclone regions of the Indian Ocean and were potentially exposed to cyclones for a substantial part of their annual cycle. However, only juvenile petrel survival was affected by cyclone activity; negatively by a strong cyclone in the vicinity of the breeding colony and positively by increasing cyclone activity in the Northern Indian Ocean where they spend the majority of their first year at sea. These contrasting effects raise the intriguing prospect that the projected changes in cyclones under current climate change scenarios may have positive as well as the more commonly perceived negative impacts on marine biodiversity.last_img read more

Ivanka Trump says it’s ‘ridiculous’ that Serena Williams is being ‘penalized’ for her pregnancy

first_img Beau Lund Written by FacebookTwitterLinkedInEmailAl Bello/Getty Images(WASHINGTON) — Ivanka Trump is not happy about the way Serena Williams was treated in the lead up to the French Open. The First Daughter came to the defense of the tennis star on social media on Thursday, writing that it was “ridiculous” that Williams was unseeded from the tennis tournament after having taken time off from the game to give birth to her daughter. “This is ridiculous,” Trump wrote in a tweet Thursday. “@SerenaWilliams is a formidable athlete (best ever!) and loving new mother. No person should ever be penalized professionally for having a child! The #WTA should change this rule immediately. #FrenchOpen.”Without being seeded, Williams, a 23-time Grand Slam winner who has won the French Open three times, could face highly-ranked opponents in the early rounds of the tournament.She returned to the World Tennis Association tour in March after giving birth to her daughter, and has won twice and lost twice.  Williams has not commented publicly about the seeding situation, but she hasn’t been laying low in recent weeks, either.Last weekend, she was in England and attended the royal wedding – as she is a friend of the newly-minted Duchess of Sussex, Meghan Markle.Copyright © 2018, ABC Radio. All rights reserved.center_img May 25, 2018 /Sports News – National Ivanka Trump says it’s ‘ridiculous’ that Serena Williams is being ‘penalized’ for her pregnancylast_img read more

UVU Women’s Basketball Incoming Freshman Helps Portugal’s U-19 Squad To Solid Finish

first_imgJune 12, 2018 /Sports News – Local UVU Women’s Basketball Incoming Freshman Helps Portugal’s U-19 Squad To Solid Finish Tags: asgrbasketball.com/Kamaile Kandiah/Maria Carvalho/Sophia Jacobsson/UVU Women’s Basketball FacebookTwitterLinkedInEmailLISBON, Portugal-This past weekend, incoming Utah Valley women’s basketball freshman Maria Carvalho helped guide AD Vagos to a runner-up finish at the Portuguese Basketball Federation U-19 National Championships.A point guard out of Lisbon, Carvalho ended the four-team final round with a top-5 ranking among all players, having amassed 12.3 points, 9.1 rebounds and a team-high 3 assists per game.Additionally, Carvalho ended up being tied for a tournament-best 2.7 steals per contest en route to finishing fourth in the MVP race at Portugal’s U-19 national tournament.The 5’8″ Carvalho is part of a five-member incoming recruiting class for the Wolverines which is ranked 165th in the nation on asgrbasketball.com, the highest ranking a recruiting class has ever received in UVU women’s basketball history.Carvalho is one of three point guards in the class, the others being 5’5″ Kamaile Kandiah and 5’3″ Sophia Jacobsson. Brad James Written bylast_img read more

Former Gunnison High Star Drew Hill Transfers To South Mountain CC

first_imgJune 28, 2018 /Sports News – Local Former Gunnison High Star Drew Hill Transfers To South Mountain CC Written by Tags: Drew Hill/Kyle McDonald/South Mountain CC FacebookTwitterLinkedInEmailPHOENIX-Per information from ksl.com Utah Valley University sportswriter Kyle McDonald, former Gunnison High baseball star pitcher Drew Hill has transferred to South Mountain CC of Phoenix.Hill, who struggled with the Wolverines, (he was 0-3 last season with a 5.79 ERA) will look to turn his collegiate fortunes around with the Cougars, one of the more storied programs in the NJCAA.Hill joins a program that has been a refuge for Division I transfers, as the Cougars have had 103 D-1 transfers since 2000.Additionally, the Cougars boast 60 MLB draft picks since 2000 as well. Brad Jameslast_img read more