1,542 research outputs found
Snagged setae: evaluating alternatives to cotton wool bungs for liquid-stored specimens
Society for the Preservation of Natural History Collections Copyright © 2018. All rights reserved. Article is available as open access. The attached file is the published pdf version
100 years of deep-sea tubeworms in the collections of the Natural History Museum, London
Despite having being discovered relatively recently, the Siboglinidae family of poly- chaetes have a controversial taxonomic history. They are predominantly deep sea tube- dwelling worms, often referred to simply as ‘tubeworms’ that include the magnificent me- tre-long Riftia pachyptila from hydrothermal vents, the recently discovered ‘bone-eating’ Osedax and a diverse range of other thin, tube-dwelling species. For a long time they were considered to be in a completely separate Phylum, the Pogonophora, but with the discovery of a segmented posterior and then conclusive DNA evidence, they were re- stored to the Phylum Annelida. In this project curation and research teams have com- bined to enhance the Museum’s collection. This has been facilitated through targeted donation requests, comprehensive digitisation, a location move to the rightful taxonomic place and teaming up with global database initiatives to promote the collection.NatSCA supports open access publication as part of its mission is to promote and support natural science collections. NatSCA uses the Creative Commons Attribution License (CCAL)
http://creativecommons.org/licenses/by/2.5/Â Â for all works we publish. Under CCAL authors retain ownership of the copyright for their article, but authors allow anyone to download, reuse, reprint, modify, distribute, and/or copy articles in NatSCA publications, so long as the original authors and source are cited. The attached file is the published version of the article
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A laser probe <sup>40</sup>Ar /<sup>39</sup>Ar and INAA investigation of four Apollo granulitic breccias
Infrared laser probe 40Ar/39Ar geochronology, instrumental neutron activation analysis (INAA) and analytical electron microscopy have been performed on four 0.5 x 1.0 x 0.3 cm polished rock tiles of Apollo 16 and 17 granulitic breccias (60035, 77017, 78155, and 79215). Pyroxene thermometry indicates that these samples were re-equilibrated and underwent peak metamorphic sub-solidus recrystallization at
1000 – 1100°C, which resulted in homogeneous mineral compositions and granoblastic textures.
40Ar/39Ar data from this study reveal that three samples (60035, 77017, and 78155) have peak metamorphic ages of ~4.1 Ga. Sample 79215 has a peak metamorphic age of 3.9 Ga, which may be related to Serenitatis basin formation. All four samples contain moderately high concentrations of meteoritic siderophiles. Enhanced siderophile contents in three of the samples provide evidence for projectile
contamination of their target lithologies occurring prior to peak metamorphism.
Post-peak metamorphism, low-temperature (<300ºC) events caused the partial resetting of argon in the two finer-grained granulites (60035 and 77017). These later events did not alter the mineralogy or texture of the rocks, but caused minor brecciation and the partial release of argon from plagioclase. Interpretation of the low-temperature data indicates partial resetting of the argon systematics to as young as 3.2 Ga for 60035 and 2.3 Ga for 77017. Cosmic ray exposure ages range from 6.4 to ~339 Ma.
Our results increase the amount of high-precision data available for the granulitic breccias and lunar highlands crustal samples. The results demonstrate the survival of pre-Nectarian material on the lunar surface and document the effects of contact metamorphic and impact processes during the pre-Nectarian Epoch, as well as the low-temperature partial resetting of ages by smaller impact events after 3.9 Ga.
The mineralogy and chemical composition of these rocks, as well as exhumation constraints, indicate that the source of heat for metamorphism was within kilometres of the surface via burial beneath impact melt sheets or hot ejecta blankets
Modification of classical electron transport due to collisions between electrons and fast ions
A Fokker-Planck model for the interaction of fast ions with the thermal
electrons in a quasi-neutral plasma is developed. When the fast ion population
has a net flux (i.e. the distribution of the fast ions is anisotropic in
velocity space) the electron distribution function is significantly perturbed
from Maxwellian by collisions with the fast ions, even if the fast ion density
is orders of magnitude smaller than the electron density. The Fokker-Planck
model is used to derive classical electron transport equations (a generalized
Ohm's law and a heat flow equation) that include the effects of the
electron-fast ion collisions. It is found that these collisions result in a
current term in the transport equations which can be significant even when
total current is zero. The new transport equations are analyzed in the context
of a number of scenarios including particle heating in ICF and MIF
plasmas and ion beam heating of dense plasmas
Thermal acclimation of leaf and root respiration: an investigation comparing inherently fast- and slow-growing plant species
We investigated the extent to which leaf and root respiration W differ in their response to short- and long-term changes in temperature in several contrasting plant species (herbs, grasses, shrubs and trees) that differ in inherent relative growth rate (RGR, increase in mass per unit starting mass and time). Two experiments were conducted using hydroponically grown plants. In the long-term (LT) acclimation experiment, 16 species were grown at constant 18,23 and 28degreesC. In the short-term (ST) acclimation experiment, 9 of those species were grown at 25/20degreesC (day/night) and then shifted to a 15/10degreesC for 7 days. Short-term Q(10) values (proportional change in R per 10degreesC) and the degree of acclimation to. longer-term changes in temperature were compared. The effect of growth temperature on root and leaf soluble sugar and nitrogen concentrations was examined. Light-saturated photosynthesis (A(sat)) was also measured in the LT acclimation experiment. Our results show that Q(10) values and the degree of acclimation are highly variable amongst species and that roots exhibit lower Q(10) values than leaves over the 15-25degreesC measurement temperature range. Differences in RGR or concentrations of soluble sugars/nitrogen could not account for the inter-specific differences in the Q(10) or degree of acclimation. There were no systematic differences in the ability of roots and leaves to acclimate when plants developed under contrasting temperatures (LT acclimation). However, acclimation was greater in both leaves and roots that developed at the growth temperature (LT acclimation) than in pre-existing leaves and roots shifted from one temperature to another (ST acclimation). The balance between leaf R and A(sat) was maintained in plants grown at different temperatures, regardless of their inherent relative growth rate. We conclude that there is tight coupling between the respiratory acclimation and the temperature under which leaves and roots developed and that acclimation plays an important role in determining the relationship between respiration and photosynthesis
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112th Congress
The economic rationale for interventions in energy markets helps inform the debate surrounding energy tax policy. This report begins by providing background on the economic rationale for energy market interventions, highlighting various market failures. After identifying possible market failures in the production and consumption of energy, possible interventions are discussed. The report concludes with an analysis of energy tax policy as it stands at the start of the 112th Congress
Halothane hepatitis with renal failure treated with hemodialysis and exchange transfusion
A 38-year-old white female, hepatitis B antigen negative, developed fluminating hepatic failure associated with oliguria and severe azotemia after two halothane anesthesia and without exposure to other hepatotoxic drugs or blood transfusions. She was treated with multiple hemodialysis and exchange blood transfusion. The combined treatment corrected the uremic abnormalities and improved her level of consciousness. The liver and kidney function gradually improved, and she made a complete recovery, the first recorded with hepatic and renal failure under these post-anesthetic conditions. Further evaluation of this combined treatment used for this patient is warranted. © 1974 The Japan Surgical Society
Medical treatment of ascites in cirrhosis
Medical treatment of cirrhotic ascites is essentially supportive, dictated by the patient's discomfort, impaired cardiovascular or respiratory function and potential for infection. Treatment of ‘simple’ ascites (moderate fluid accumulation, serum albumin > 3.5 g/dl, serum creatinine < 1.5 mg/dl, no electrolyte disturbance) is implemented sequentially. Only 10% of patients respond to dietary sodium restriction and bed rest; most require pharmacotherapy consisting of spironolactone, which increases the proportion of responding patients to 65% and loop diuretics, which may produce clinical improvement in an additional 20% (85% in all); in the remaining 15% of refractory patients, use of novel adjunctive therapies may be attempted. Patients with tense ascites, impaired renal function and electrolyte disturbances merit special consideration before diuretics are introduced. Spironolactone has long been a standard for the treatment of cirrhotic ascites because it directly antagonizes aldosterone. The loop diuretic most frequently added to spironolactone has been furosemide. However, there is preliminary evidence that torasemide may be more effective in some patients. Other investigational agents that may play a role in treatment of patients resistant to conventional drugs include ornipressin (a vasopressin analogue) and atrial natriuretic factor
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