Month: May 2021

In situ measurements of transionospheric VLF wave injection

first_imgVLF waves at 3.85 kHz from the Siple, Antarctica, transmitter were continuously measured by electric and magnetic receivers on a sounding rocket as the waves propagated through the neutral atmosphere and into the ionosphere. The change from linear to circular polarization was clearly observed along with severe attenuation of the VLF signal in the D region. Interferometric measurements established the index of refraction and provided an independent calibration of the rocket‐borne receivers. An upper bound on the VLF power radiated is estimated to be 1.7×10³ W during a period when the antenna was driven at 115×10³ W. The power estimated to be entering the ionosphere is between 3 W and 12 W and depends on assumptions concerning the geometrical distribution of wave power.last_img read more

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A suggested model for the IRI plasmapheric distribution

first_imgA model has been constructed which grafts IRI topside profiles to field-aligned diffusive equilibrium profiles at a “reference level” near 650 km altitude. For different values of geographic latitude, longitude, sunspot number, season and time, the properties of the plasma distribution in the equatorial plane are investigated. These are compared with observations made by satellite (particularly GEOS and ISEE) and also with deductions made from whistler observations.last_img

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Seasonal variation in the effects of hard substratum biofilming on settlement of marine invertebrate larvae

first_imgThe effect of season on “biofilming”;, as a cue for the settlement of marine invertebrate larvae, was investigated in a long‐term field study during the years 1992–1994. The series of settlement experiments was conducted in a tidal rapid on the west coast of Scotland, and involved manipulations of artificial panels. Biofilming of substrata, whilst excluding larval settlement, was achieved by the enclosure of panels within tight‐fitting (but removable) mesh screens so that the number of settlers on filmed and unfilmed substrata were counted in the initial absence of other incumbent post‐larvae. Depending on larval species, the effects of biofilming were found to be either facilitatory or inhibitory. Significant within‐ and between‐species seasonal differences in the settlement responses were detected, and a reversal of the effect of biofilming on larval settlement response, from inhibitory to facilitatory and vice versa, was noted with season in the case of some taxonomic groups and species (e.g. Tubulipora sp., Plagioecia sp., Electra pilosa (L.)). The present study emphasizes the need for extended field studies of larval responses to environmental cues, when the focus of interest is in drawing general inferences about naturally occurring behavioural patterns at settlement.last_img read more

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Krill fishing in the Scotia Sea in relation to bathymetry, including the detailed distribution around South Georgia

first_imgAnalyses of the distribution of krill fishing based on fine-scale (0.5″ latitude x1″ longitude) data show that harvesting in the Scotia Sea has been mainly in shelf andshelf-break areas on the northern side of the Scotia Arc. Regional analyses reveal thattliere are restricted parts of shelf and shelf-break areas where high catches have beenobtained. Altliough these data give a general idea of where the fishery has operated,they do not reveal the localised nature of the fishing operation. Over the last threewinter fishing seasons (1993 to 1995) individual trawl statistics have been recorded inthe South Georgia area. Analyses of these data show marked interannual variability inthe distribution of trawls. The data for 1993 were only available from August but thefishery was restricted in that period to an area on the western edge of the shelf breakwhere negligible fishing occurred in the following two seasons. In 1994 the fishery wasalmost totally based over a large shallow bank area on the northeast shelf edge. During1995 the fishery was still predominantly in this area but also operated further west 011 arange of banks associated with submarine valleys. The results are discussed in relationto the ecology of krill and the fishery’s interaction with local predator colonieslast_img read more

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The Polonez Cove Formation of King George Island, Antarctica: stratigraphy, facies and implications for mid-Cenozoic cryosphere development

first_imgThe middle to late Oligocene Polonez Cove Formation, exposed on south-eastern King George Island, South Shetland Islands, provides rare evidence of mid-Cenozoic West Antarctic cryosphere evolution. A revised lithostratigraphy and facies analysis and a review of the palaeoenvironmental significance of the formation are presented here. The diamictite-dominated basal member of the formation (Krakowiak Glacier Member) records the presence and retreat of marine-based ice on a shallow continental shelf. Five overlying members are recognized. These consist of basaltic-sourced sedimentary rocks and lavas and represent a variety of shoreface and shallow continental shelf environments in an active volcanic setting. These units contain diverse reworked and ice-rafted exotic clasts that become sparse towards the top of the formation, suggesting a continuing but waning glacial influence. New 40Ar/39Ar dates from interbedded lava flows indicate a late Oligocene age (25·6–27·2 Ma) for the Polonez Cove Formation, but are slightly younger than skeletal carbonate Sr-isotope ages obtained previously (28·5–29·8 Ma). There is evidence for wet-based subice conditions at the base of the Polonez Cove Formation, but no sedimentary facies to suggest substantial meltwater. This may reflect a subpolar setting or may result from lack of preservation or a high-energy depositional environment. A northern Antarctic Peninsula/South Shetland Islands provenance is probable for most non-basaltic clasts, but certain lithologies with possible origins in the Transantarctic and Ellsworth Mountains also occur sparsely throughout the formation. There is evidence to suggest that the presence of such far-travelled clasts within subglacially deposited facies at the base of the formation reflects the advance of a local ice cap across marine sediments containing the clasts as ice-rafted material. The presence of these clasts suggests that extensive marine-based ice drained into the southern Weddell Sea region and that a strong Weddell Sea surface current operated both before and during deposition of the Polonez Cove Formation.last_img read more

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Geophysical Validation of SCIAMACHY NO2 Vertical Columns: Overview of Early 2004 Results.

first_imgFollowing the recommendations drawn after the Commissioning Phase of the ENVISAT satellite in 2002, SCIAMACHY near real time data processors were upgraded to version 5.01 in early 2004. Before public release of the new SCIAMACHY nitrogen dioxide (NO2) vertical column data product, several validation teams investigated its improvement and assessed its geophysical consistency by means of correlative studies involving NDSC-affiliated groundbased networks of DOAS UV-visible and FTIR spectrometers and the ERS-2 GOME satellite. In parallel, preliminary SCIAMACHY NO2 column data products generated by research processors under development at scientific institutes were also tested, using the same correlative data and validation procedures. Digesting the results obtained by a list of validation teams and SCIAMACHY data processing teams, this overview paper draws a preliminary quality assessment of the SCIAMACHY NO2 column data sets available in spring 2004.last_img read more

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Inferring sites of subglacial erosion using the Pb isotopic composition of ice-rafted feldspar: Examples from the Weddell Sea, Antarctica

first_imgThe delivery of ice-rafted debris (IRD) from glaciated margins is a function of ice sheet dynamics. Shifts in supply and sourcing of IRD can therefore identify episodes of ice sheet instability; however, records can be difficult to correctly interpret because the subglacial geology of the catchment areas, which controls IRD composition, may be obscured. Importantly, variations can also result from shifts in erosion sites due to changes in the basal ice sheet conditions. This study evaluates where subglacial erosion has occurred in catchments that flow into the southern Weddell Sea, Antarctica, by determining the Pb isotopic compositions of individual ice-rafted feldspars from late Holocene marine sediments. Feldspar compositions match those of rock units inferred (through extrapolation of outcrop, magnetic, and gravity data) to compose areas where ice velocity, bed roughness, and shear stress are high. Significantly, signals from areas where ice velocities are high but bed roughness and shear stresses are low were not recorded, suggesting that there is reduced bedrock erosion in these regions. Major variations in IRD composition in the Weddell Sea can result from changing the loci of subglacial erosion, and do not necessarily correspond with major ice sheet instability.last_img read more

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Prep Sports Roundup: 3/23

first_img FacebookTwitterLinkedInEmailBoys BasketballHOLLADAY, Utah-Kade Lamborn and Sano Gasana had 17 points apiece as the 2-A All-Stars downed the 1-A All-Stars 91-83 Friday at Olympus High School. Panguitch’s Jace Eyre had 21 points in the loss for the 1-A All-Stars.HOLLADAY, Utah-Boston Douglas led the way with 16 points and the 3-A All-Stars bested the 4-A All-Stars 111-106 at Olympus High School Friday. Delta’s Brett Roundy posted 14 points and Max Gurney of Juab added 12 more points in the win.SoftballRegion 15BLANDING, Utah-Graciee Christiansen and Addelyn Brotherson each tripled as the North Sanpete Hawks routed San Juan 11-1 Friday in the first game of a Region 15 softball doubleheader.BLANDING, Utah-Brooke Price went yard, helping the North Sanpete Hawks to a 13-3 win over San Juan, completing a Region 15 softball doubleheader sweep Friday.Baseball2-A NorthGUNNISON, Utah-Avery Anderson, Bowen Jensen, Chance Helms, Creed Mogle and Ty Hill each doubled as the Gunnison Bulldogs pounded Duchesne 20-1 Friday in 2-A North baseball action.Region 15MONROE, Utah-Easton Hunt homered twice, including a grand slam, and finished with six RBI to lead the South Sevier Rams to a 15-5 rout of Emery Friday in Region 15 baseball action. Gage Ekker earned the win on the mound in a complete game five inning performance.Non-RegionENTERPRISE, Utah-Andrew Bowler earned the win on the mound as the Enterprise Wolves outlasted the North Sevier Wolves 3-2 in non-region baseball action Friday. Brad James Written by Tags: Baseball/Boys Basketball/Brett Roundy/Gunnison/Jace Eyre/Max Gurney/North Sanpete/Softball/South Sevier March 23, 2018 /Sports News – Local Prep Sports Roundup: 3/23last_img read more

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Eric Reid takes a knee during national anthem upon his return to the NFL

first_imgOctober 7, 2018 /Sports News – National Eric Reid takes a knee during national anthem upon his return to the NFL Beau Lund Written bycenter_img FacebookTwitterLinkedInEmailGrant Halverson/Getty Images(NEW YORK) —  Eric Reid, a defensive back with the Carolina Panthers, took a knee on the field on Sunday during the national anthem before a game against the New York Giants.The game marked Reid’s return to the NFL after an uncertain few months as a free agent which he believes were because of his continued protests against racism and police brutality.Reid’s contract with the San Francisco 49ers expired in March and he remained unsigned until two weeks ago, when he joined the Panthers on a one-year contract.The news of Reid rejoining the NFL came amid speculation by some fans and players that the 26-year-old had not been signed due to his activism on the field.“I think we all know why he hasn’t received a call,” Carolina Panthers wide receiver Torrey Smith, a member of the NFL Players Coalition, said days before Reid was signed by the Panthers, echoing a suggestion previously made by others in the coalition, including Devin McCourty from the New England Patriots, and Malcolm Jenkins from the Philadelphia Eagles.“The notion that I can be a great signing for your team for cheap, not because of my skill set but because I’ve protested systemic oppression, is ludicrous,” Reid tweeted in March.Reid was the first to join teammate Colin Kaepernick in taking a knee during the National Anthem in 2016.He continued his protest even after Kaepernick’s contract wasn’t renewed at the end of the 2016 season, and he and other players who followed suit have become targets of President Donald Trump, who launched an ongoing battle with the NFL in September 2017 for allowing the protests. In August of this year, Trump said that players who don’t take a knee should be “suspended without pay.”Reid and Kaepernick filed a grievance against the NFL in May, claiming that league owners colluded to keep them from playing because of their protests on the field.Reid said last week he wasn’t sure whether his protests for social justice would include taking a knee during the national anthem but added that he doesn’t plan on dropping his grievance against the NFL even after getting signed.Kaepernick, who has remained unsigned, has continued to work for social justice issues, becoming a symbol of the modern civil rights movement.On Sunday, Kaepernick tweeted his support for Reid’s protest.“My Brother @E_Reid35, with @KSTiLLS and @iThinkIsee12, continue to take a knee against systemic oppression. They are unwavering in their conviction! #ImWithReid,” former San Francisco 49ers quarterback Colin Kaepernick tweeted on Sunday, in support of Reid.ABC News has reached out to the NFL for a request for comment, but a call was not immediately returned.Copyright © 2018, ABC Radio. All rights reserved.last_img read more

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Chicago Bulls fire Fred Hoiberg, name Jim Boylen head coach

first_img Written by FacebookTwitterLinkedInEmailPhil Ellsworth/ESPN Images(NEW YORK) — The Chicago Bulls have fired head coach Fred Hoiberg after a 5-19 start to the season.Hoiberg coached the team starting in 2015, leading them to a playoff appearance in 2016.Bulls vice president of basketball operations John Paxson thanked Hoiberg for his time with the team, and insisted the move was not about the team’s poor start to the season.“At media day, [General Manager Gar Forman] and I spoke about how we weren’t going to evaluate things based on wins and losses,” he told reporters. “This decision was not based on our record.”The Bulls have started the season missing some key players, including starting point guard Kris Dunn and small forward Lauri Markannen who only made his season debut on Dec. 1. Paxson also told reporters the injured players were not an excuse.“What we’re lacking is kind of an energy and spirit about our team and we need to get that back,” he said. “It’s not as simple as saying we would’ve gotten that with healthy players, with Lauri coming back, Kris Dunn coming back, Bobby [Portis] coming back. It wasn’t going to be that simple.”Assistant coach Jim Boylen has been tapped to replace Hoiberg as head coach on a long term basis, and not just as an interim coach.“I think it sends a message to the team that they have faith in me,” he told reporters. “We’re going to try to build this thing from where Fred had it.”Boylen has served with an assistant for several NBA teams, including the Indiana Pacers and the San Antonio Spurs. His only prior head coaching experience was for four seasons at the University of Utah.Boylen will most likely want to start with improving the team’s offense. The Bulls are 28th in points per game with 103.4.Copyright © 2018, ABC Radio. All rights reserved. December 4, 2018 /Sports News – National Chicago Bulls fire Fred Hoiberg, name Jim Boylen head coachcenter_img Beau Lundlast_img read more

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