Survival and water loss in some Antarctic arthropods

first_imgSeven species of Antarctic micro-arthropods (4 mites and 3 collembolans) were examined to determine their resistance to dehydration and their survival under dry conditions. Water loss at r.h. 5% at temperatures in the range −10 to 45°C was measured gravimetrically using a recording micro-balance. Survival of samples of mites was monitored after exposure to r.h. 5% and temperatures in the range 0–20°C. Rates of water loss ranged from 0 to about 30% fresh weight h−1 depending on temperature and species. The 3 Collembola were least resistant and the 2 oribatid mites were most resistant to dehydration under the experimental conditions. The optimal survival temperature of the mite Alaskozetes antarcticus was around 10°C under 5% r.h.; there were no significant differences in rate of water loss between temperatures. The results are discussed in terms of possible control mechanisms and the type of habitat occupied by each species.last_img read more

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The theory of radio windows in planetary magnetospheres

first_imgThe theory of radio windows given in two previous papers for a stratified cold plasma is extended to apply in a warm plasma. It is used to investigate one suggested mechanism for the production of non-thermal continuum radiation in magnetospheric cavities. The source is a plasma wave that enters a region where there is a gradient of electron concentration and there undergoes partial linear mode conversion to give ordinary and extraordinary electromagnetic waves and a reflected plasma wave. This theory is needed particularly for the plasmapause and magnetopause where the concentration gradients may be large. It is therefore necessary to use a full-wave integration of the governing differential equations. These are derived for a warm plasma. When they are integrated, the problem of numerical swamping is severe and is dealt with by a special method. Some typical results are presented and discussed.last_img read more

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Environmental assessment in the Antarctic

first_imgEnvironmental impact assessment (EIA) is generally recognized as a useful tool in reducing human impacts on the environment. The Antarctic environment is especially sensitive to harmful perturbation. Regulations introduced under the Antarctic Treaty have provided limited environmental protection. Following proposals from the Scientific Committee on Antarctic Research, the XIV Antarctic Treaty Consultative Meeting in October 1987 adopted a Recommendation which suggested guidelines to be used in a formal system of environmental impact assessment for scientific research and associated logistic activities in the Antarcticlast_img read more

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Prospects for survival in the Southern Ocean: vulnerability of benthic species to temperature change

first_imgOrganisms have a limited number of responses that enhance survival in changing environments. They can: 1. Cope within existing physiological flexibility; 2. Adapt to changing conditions; or 3. Migrate to sites that allow survival. Species inhabiting coastal seabed sites around Antarctica have poorer physiological capacities to deal with change than species elsewhere. They die when temperatures are raised by only 5–10°C above the annual average, and many species lose the ability to perform essential functions, e.g. swimming in scallops or burying in infaunal bivalve molluscs when temperatures are raised only 2–3°C. The ability to adapt, or evolve new characters to changing conditions depends, at least in part, on generation time. Antarctic benthic species grow slowly and develop at rates often x5–x10 slower than similar temperate species. They also live to great age, and exhibit deferred maturity. Longer generation times reduce the opportunities to produce novel mutations, and result in poorer capacities to adapt to change. Intrinsic capacities to colonize new sites and migrate away from deteriorating conditions depend on adult abilities to locomote over large distances, or for reproductive stages to drift for extended periods. The slow development of Antarctic benthic species means their larvae do spend extended periods in the water column. However, whereas most continents have coastlines extending over a wide range of latitude, Antarctica is almost circular in outline, is isolated from other oceans by the circumpolar current, and its coastline covers few degrees of latitude. Thus in a warming environment there are fewer places to migrate to. On all three major criteria Antarctic benthic species appear less capable than species elsewhere of responding to change in ways that can enhance survival.last_img read more

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Simulation of EMIC wave excitation in a model magnetosphere including structured high-density plumes

first_imgThe HOTRAY code is used to evaluate the path integrated gain of electromagnetic ion cyclotron (EMIC) waves as a function of frequency in two propagation bands above the O+ and He+ gyrofrequencies. Calculations are performed over a range of L shell (3 < L 40 dB) is found near the plasmapause, within regions with density structure in the plume, and in the low-density trough at L >= 6.5. As a self-consistent test on whether EMIC waves play an important role in relativistic electron loss from the radiation belts, the minimum cyclotron resonant electron energy is evaluated as a function of wave frequency and L shell for those EMIC waves that exhibit significant gain. The lowest electron resonant energies (approximately a few MeV) are found in structured plumes. The sensitivities of both the wave gain and electron minimum resonant energy to variation in thermal ion compositions, the energetic proton properties, or plume density structure are also investigated.last_img read more

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Demographic parameters of black-browed albatrosses Thalassarche melanophris from the Falkland Islands

first_imgBlack-browed albatrosses Thalassarche melanophris are currently classified as globally endangered. The most important populations of this species are believed to be declining due to, amongst other factors, unsustainable levels of incidental mortality in fishing gear. However, detailed demographic data are lacking for several critical populations, including the largest of all, nesting in the Falkland Islands. Here, we present data from the first Falkland Islands detailed demographic study (at New Island) and show that, from 2003 to 2009, the mean adult survival probability was 0.942 (95% CI: 0.930-0.952). Nesting frequency of adults is amongst the highest recorded for Thalassarche albatrosses and breeding success (0.564 chicks per egg) is within normal values. The nesting population in the intensively studied plots experienced an increase of 4% per year from 2004 to 2009. These results indicate that the Falklands population may not be as threatened as previously supposed, although studies from more sites and a longer time series are needed to confirm or refute this. The high survival rates may partly reflect recent efforts to mitigate bycatch made by the Falkland Islands and other fisheries in the region. The reinforcement of such initiatives may be critical to buffer the black-browed albatross population against ecosystem shifts and natural disasters (such as harmful algal blooms) that will likely become more frequent with ongoing global changes.last_img read more

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Warm climate isotopic simulations: what do we learn about interglacial signals in Greenland ice cores?

first_imgMeasurements of Last Interglacial stable water isotopes in ice cores show that central Greenland d18Oincreased by at least 3& compared to present day. Attempting to quantify the Greenland interglacialtemperature change from these ice core measurements rests on our ability to interpret the stable waterisotope content of Greenland snow. Current orbitally driven interglacial simulations do not show d18O ortemperature rises of the correct magnitude, leading to difficulty in using only these experiments toinform our understanding of higher interglacial d18O. Here, analysis of greenhouse gas warmed simulationsfrom two isotope-enabled general circulation models, in conjunction with a set of Last Interglacialsea surface observations, indicates a possible explanation for the interglacial d18O rise. A reduction in thewinter time sea ice concentration around the northern half of Greenland, together with an increase in seasurface temperatures over the same region, is found to be sufficient to drive a >3& interglacialenrichment in central Greenland snow. Warm climate d18O and dD in precipitation falling on Greenlandare shown to be strongly influenced by local sea surface condition changes: local sea surface warmingand a shrunken sea ice extent increase the proportion of water vapour from local (isotopically enriched)sources, compared to that from distal (isotopically depleted) sources. Precipitation intermittencychanges, under warmer conditions, leads to geographical variability in the d18O against temperaturegradients across Greenland. Little sea surface warming around the northern areas of Greenland leads tolow d18O against temperature gradients (0.1e0.3& per �C), whilst large sea surface warmings in theseregions leads to higher gradients (0.3e0.7& per �C). These gradients imply a wide possible range ofpresent day to interglacial temperature increases (4 to >10 �C). Thus, we find that uncertainty about localinterglacial sea surface conditions, rather than precipitation intermittency changes, may lead to thelargest uncertainties in interpreting temperature from Greenland ice cores. We find that interglacial seasurface change observational records are currently insufficient to enable discrimination between thesedifferent d18O against temperature gradients. In conclusion, further information on interglacial sea surfacetemperatures and sea ice changes around northern Greenland should indicate whether þ5 �C duringthe Last Interglacial is sufficient to drive the observed ice core d18O increase, or whether a larger temperatureincreases or ice sheet changes are also required to explain the ice core observations.last_img read more

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Utah Men’s Tennis Aces Pac-12 Academic Awards

first_imgMay 29, 2018 /Sports News – Local Utah Men’s Tennis Aces Pac-12 Academic Awards FacebookTwitterLinkedInEmailSALT LAKE CITY-Tuesday,  University of Utah men’s tennis capped off a successful on-court season by setting a new program record for academic achievement.The Utes placed seven student-athletes on the Pac-12 All-Academic squads, showing the Utes can both ace the textbooks as well as their competition.Senior Egbert Weverink of Amsterdam, The Netherlands became the second Ute in program history to earn 1st team Pac-12 all-academic honors in consecutive seasons.Furthermore, Slava Shainyan, a sophomore from Moscow, Russia was selected to the all-Pac-12 first team, his first honor as a Ute.Making the second team was senior Santiago Sierra of Mexico City, Mexico as he joined current Utes’ assistant Matt Cowley as the only Ute in program history to earn Pac-12 all-academic honors in three consecutive seasons. Joining Sierra on the second team were junior Dan Allen of London, England, junior Joe Woolley of Boston, England and junior David Micevski of Skopje, Macedonia.Earning honorable mention honors for the Utes was redshirt sophomore Azat Hankuliyev of Salt Lake City. This was his first postseason recognition from the Pac-12.Since joining the Pac-12 in 2012, Utah men’s tennis has had 17 student-athletes earn 31 Pac-12 all-academic honors.In order to eligible for selection to the Pac-12’s all-academic squad, a student-athlete must have a minimum 3.0 GPA and compete in at least 50 percent of his team’s matches in men’s tennis. Brad James Tags: All-Academic Squad/Azat Hankuliyev/Dan Allen/David Micevski/Egbert Weverink/Joe Woolley/Matt Cowley/Santiago Sierra/Slava Shainyan/Utah Men’s Tennis Written bylast_img read more

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Major League Baseball announces plan to implement pitch clock during Spring Training

first_img Written by FacebookTwitterLinkedInEmailpoetic_disorder/iStock(NEW YORK) — Major League Baseball has announced that it will implement a pitch timer during Spring Training games, with the potential for that mechanism to be used in regular season games as well.According to a news release, the 20-second clock will be implemented in three stages. Initially, the timer will be used without enforcement as umpires and players become familiar with the rule. Beginning next week, umpires will be instructed to remind pitchers and hitters who violate the rule with no penalty. And later in Spring Training, batters will be required to be in the batter’s box and alert to the pitcher with at least five seconds remaining on the clock. The pitcher will have to begin his windup or come to a set position before the timer expires. A ball or strike will be assessed based on which party violates the rule.MLB says the timer will not be used on the first pitch of an at-bat. On any ensuing pitch, the clock will start when the pitcher receives the ball back from the catcher.Negotiations between the league and the MLB Players Union will determine whether the rule will also be used in the regular season. Copyright © 2019, ABC Radio. All rights reserved. February 22, 2019 /Sports News – National Major League Baseball announces plan to implement pitch clock during Spring Trainingcenter_img Beau Lundlast_img read more

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Cancer survivor David Quessenberry gets first NFL touchdown catch

first_img Written by September 16, 2019 /Sports News – National Cancer survivor David Quessenberry gets first NFL touchdown catch Beau Lundcenter_img FacebookTwitterLinkedInEmail33ft/iStock(NASHVILLE, Tenn.) — The Tennessee Titans pulled off an epic touchdown pass to offensive lineman David Quessenberry on Sunday, which made his fourth career NFL game extra special for the cancer survivor. The 1-yard pass from quarterback Marcus Mariota notched the offensive tackle’s first touchdown in the NFL.“It was a simple route — any of the offensive linemen on this team could have caught that ball,” Quessenberry said after the game. “I just happened to be the guy who had his number called on that play and was able to come down with it. All I was thinking was, ‘Don’t drop it.’”But what made the moment even more memorable, Quessenberry was diagnosed with non-Hodgkin’s lymphoma in June 2014 while he was with the Houston Texans and battled back to make the final 53-man roster with the Titans this year. “I have been through a lot, and it has been a long journey to get here,” Quessenberry said. “Even with all of that, to go out there and score a touchdown, it is crazy. That was amazing. It was epic.”In February 2015, his cancer went into remission after radiation was completed and once he completed his full treatment in April 2017, he returned to practice with the team before moving to Tennessee last year. Quessenberry’s teammates rushed the end zone upon his TD catch at their home opener in Nissan Stadium on Sunday, but the team fell short to the Indianapolis Colts 19-17. Copyright © 2019, ABC Radio. All rights reserved.last_img read more

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