671 research outputs found
Loki, Io: New groundbased observations and a model describing the change from periodic overturn
Loki Patera is the most powerful volcano in the solar system. We have
obtained measurements of Loki's 3.5 micron brightness from NASA's Infrared
Telescope Facility (IRTF) and have witnessed a change from the periodic
behavior previously noted. While Loki brightened by a factor of several every
540 days prior to 2001, from 2001 through 2004 Loki remained at a constant,
medium brightness. We have constructed a quantitative model of Loki as a
basaltic lava lake whose solidified crust overturns when it becomes buoyantly
unstable. By altering the speed at which the overturn propagates across the
patera, we can match our groundbased brightness data. In addition, we can match
other data taken at other times and wavelengths. By slowing the propagation
speed dramatically, we can match the observations from 2001-2004. This slowing
may be due to a small change in volatile content in the magma
The Sandwich algorithm for spatial equilibrium analysis
Recent advances in mathematical programming techniques have
made it possible to provide more realistic solutions to applied
economic problems. Although mathematical programming techniques are
widely used, the economic content of the solutions is often limited by
the assumptions imposed by the algorithms available. This report is
designed to demonstrate the increased flexibility which is currently
available for the solution of a wide range of spatial economic
problems.
Transportation and transhipment models have been widely used in
the analysis of the impact of policy changes on spatial activity,
Borrell & Zwart [l]; Beck, Rathbun and Abbott [2]. One of the major
shortcomings of such models has been an inability to model the impact
of more flexible pricing policies on regional supply and demand, while
maintaining the realistic non linearities which are associated with
processing and transportation costs. In this paper a simplified
version of the transhipment model developed by Borrell & Zwart [l] is
modified to incorporate regional supply response while at the same time
retaining complex processing and handling cost relationships.
This report outlines the general form of the spatial
equilibrium problem and some of the solution techniques available, in a
format easily understood by readers not conversant with operational
research techniques. Initially the problem is defined and solution
methods used in the past are then briefly described. The advantages
and disadvantages of these methods are outlined before showing how a
relatively new solution technique may be able to improve both the scope
and flexibility of the problems being solved
Preliminary Archeological Investigations at the Callawassie Island Burial Mound (38BU19), Beaufort County, South Carolina
https://scholarcommons.sc.edu/archanth_books/1176/thumbnail.jp
Consumption of Aquatic Plants by the West Indian Manatee
Because manatees (Trichechus manatus) are large aquatic herbivores they have often been considered as potential control agents for aquatic plants. Several problems are associated with this concept, and a major one has been the gap in knowledge concerning food consumption rates of manatees. We estimated food consumption by measuring chews per unit time, chews per amount of food consumed, and time spent chewing food. Data were collected on captive manatees of various sizes and used to construct regression equations that predict consumption rates based on body size. Time budget data were obtained by radiotelemetry of free-ranging animals. Estimates of consumption rates for manatees eating hydrilla (Hydrilla verticillata Royle) were compared to the estimates biomass of hydrilla in Kings Bay, Florida, the overwintering site for a large manatee populations (116 in the winter of 1980-1981). Estimates show that nearly ten times as many manatees would have been needed just to consume the standing biomass of hydrilla. The inefficiency of manatees as control agents for aquatic plants becomes even more apparent when plant productivity is included in these estimates
Phylogeny and taxonomy of the round-eared sengis or elephant-shrews, genus Macroscelides (Mammalia, Afrotheria, Macroscelidea)
CITATION: Dumbacher, J. P., Rathbun, G. B., Smit, H. A. & Eiseb, S. J. 2012. Phylogeny and taxonomy of the round-eared sengis or elephant-shrews, genus Macroscelides (Mammalia, Afrotheria, Macroscelidea). PLoS ONE, 7(3):e32410, doi:10.1371/journal.pone.0032410.The original publication is available at http://journals.plos.org/plosoneThe round-eared sengis or elephant-shrews (genus Macroscelides) exhibit striking pelage variation throughout their ranges. Over ten taxonomic names have been proposed to describe this variation, but currently only two taxa are recognized (M. proboscideus proboscideus and M. p. flavicaudatus). Here, we review the taxonomic history of Macroscelides, and we use data on the geographic distribution, morphology, and mitochondrial DNA sequence to evaluate the current taxonomy. Our data support only two taxa that correspond to the currently recognized subspecies M. p. proboscideus and M. p. flavicaudatus. Mitochondrial haplotypes of these two taxa are reciprocally monophyletic with over 13% uncorrected sequence divergence between them. PCA analysis of 14 morphological characters (mostly cranial) grouped the two taxa into non-overlapping clusters, and body mass alone is a relatively reliable distinguishing character throughout much of Macroscelides range. Although fieldworkers were unable to find sympatric populations, the two taxa were found within 50 km of each other, and genetic analysis showed no evidence of gene flow. Based upon corroborating genetic data, morphological data, near sympatry with no evidence of gene flow, and differences in habitat use, we elevate these two forms to full species. © 2012 Dumbacher et al.http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0032410Publisher's versio
Advances in studying phasic dopamine signaling in brain reward mechanisms
The last sixty years of research has provided extraordinary advances of our knowledge of the reward system. Since its discovery as a neurotransmitter by Carlsson and colleagues (1), dopamine (DA) has emerged as an important mediator of reward processing. As a result, a number of electrochemical techniques have been developed to measure DA in the brain. Together, these techniques have begun to elucidate the complex roles of tonic and phasic DA signaling in reward processing and addiction. In this review, we will first provide a guide for the most commonly used electrochemical methods for DA detection and describe their utility in furthering our knowledge about DA's role in reward and addiction. Second, we will review the value of common in vitro and in vivo preparations and describe their ability to address different types of questions. Last, we will review recent data that has provided new mechanistic insight of in vivo phasic DA signaling and its role in reward processing and reward-mediated behavior
Competencies Through Community Engagement: Developing the Core Competencies for Cataloging and Metadata Professional Librarians
In 2015 the Association for Library Collections and Technical Services Cataloging and Metadata Management Section (ALCTS CaMMS) Competencies for a Career in Cataloging Interest Group (CECCIG) charged a task force to create a core competencies document for catalogers. The process leading to the final document, the Core Competencies for Cataloging and Metadata Professional Librarians, involved researching the use of competencies documents, envisioning an accessible final product, and engaging in collaborative writing. Additionally, the task force took certain measures to solicit and incorporate feedback from the cataloging community throughout the entire process. The Competencies document was approved by the ALCTS Board of Directors in January 2017. Task force members who were involved in the final stages of the document’s creation detail their processes and purposes in this paper and provide recommendations for groups approaching similar tasks
Split Suckling, Birth Order, and Birth Weight Affects Colostrum Intake and Pre-Weaning Weight Gain
Thirty sows (DNA Line 241, n = 10/treatment) and litters (sired by Line 600, pigs n = 412) were used to determine the effects of split suckling on immunocrit, colostrum intake, and growth of low birth weight pigs and pigs that farrow last in the birth order. Three treatments were used 1) control, all pigs suckled ad libitum; 2) weight based, the heaviest 6 pigs were removed for 1.5 h; or 3) birth order based, the first half of the litter was removed for 1.5 h. Over all litters, heavier pigs at birth had greater (P \u3c 0.01) colostrum intake and pigs born in the last half of the litter had lower (P \u3c 0.01) immunocrits (a measure of circulating immunoglobulins) than pigs born in the first half of the litter. Removing the heaviest 6 pigs for 1.5 h beginning 6 h after farrowing resulted in increased (P \u3c 0.05) weight gain by d 7. A tendency (P = 0.15) for treatment × birth order interactions suggests that split suckling increased colostrum intake for the later born pigs
Participation of women scientists in ESA solar system missions: A historical trend
We analyzed the participation of women scientists in 10 ESA (European Space Agency) Solar System missions over a period of 38 years. Being part of a spacecraft mission science team can be considered a proxy to measure the "success"in the field. Participation of women in PI (Principal Investigators) teams varied between 4% and 25 %, with several missions with no women as PI. The percentage of female scientists as Co-I (Co-Investigators) is always less than 16 %. This number is lower than the percentage of women in the International Astronomical Union from all ESA's Member State (24 %), which can give us an indication of the percentage of women in the field. We encountered many difficulties to gather the data for this study. The list of team members were not always easily accessible. An additional difficulty was to determine the percentage of female scientists in planetary science in Europe. We would like to encourage the planetary community as a whole, as well as international organizations, universities and societies to continuously gather statistics over many years. Detailed statistics are only the first step to closely monitor the development of achievement gaps and initiate measures to tackle potential causes of inequity, leading to gender inequalities in STEM careers
- …