907 research outputs found
Round Goby Predation on Smallmouth Bass Offspring in Nests during Simulated Catch-and-Release Angling
Round goby Neogobius melanostomus first appeared in Lake Erie in 1993 and now
occur in extremely high densities in some areas. As known nest predators, round goby currently
pose a threat to nest-guarding smallmouth bass Micropterus dolomieu. We conducted manipulative
experiments to evaluate the combined effects of round goby predation and catch-and-release angling
during 1999–2001 in the Bass Islands, Lake Erie. We quantified how many smallmouth bass
offspring were consumed by round goby when nest-guarding smallmouth bass males were present,
removed, and recovering from angling-related stress. In 10 h of video observations, we only saw
one instance of round goby consuming smallmouth bass offspring while the nest was guarded.
Upon removal of nest-guarding smallmouth bass, round goby quickly entered unguarded nests
(4.3 round goby/min for nests with unhatched embryos and 1.8 round goby/min for nests with
hatched embryos). During experimental catch-and-release angling, round goby consumed an average
of 2,000 unhatched embryos before the guardian male returned, but postreturn offspring
losses were minimal while the male recovered from angling stress. For an average smallmouth
bass nest in the Bass Islands, round goby could consume all offspring from an unguarded nest in
about 15 min. Round goby predation and smallmouth bass angling combined to reduce survival
of smallmouth bass embryos, but we did not observe round goby consuming free-swimming larvae
or juveniles. If the number of surviving smallmouth bass embryos drives adult population size,
managers should consider angling regulations that reduce interference with nesting males, thus limiting the deleterious effects of round goby.This research was funded by Federal Aid in Sport Fish Restoration Project
F-69-P, administered jointly by the U.S. Fish and Wildlife Service and the Ohio Department of Natural Resources, Division of Wildlife, and the Department of Evolution, Ecology, and Organismal Biology at Ohio State University
Increased parental care cost for nest-guarding fish in a lake with hyperabundant nest predators
Although parental care increases offspring survival, providing care is costly, reducing parental growth and survival and, thereby, compromising future reproductive success. To determine if an exotic benthic predator might be affecting parental care by nest-guarding smallmouth bass (Micropterus dolomieu), we compared nest-guarding behavior and energy expenditures in two systems, one with a hyperabundant recently introduced predator, the round goby (Neogobious melanostomus). In Lake Erie, USA, smallmouth bass vigorously defended their nests from benthic round gobies. In Lake Opeongo, Canada, smallmouth bass were exposed to fewer and predominantly open-water predators and were less active in their nest defense. From scuba and video observations, we documented that nest-guarding smallmouth bass chased predators (99% of which were round gobies) nine times more frequently in Lake Erie than in Lake Opeongo. This heightened activity resulted in a significant decline in weight and energetic content of guarding males in Lake Erie but no change in Lake Opeongo males. Bioenergetic simulations revealed that parental care increased smallmouth bass standard metabolic rate by 210% in Lake Erie but only by 28% in Lake Opeongo. As energy reserves declined and offspring became increasingly independent, males in both lakes consumed more prey and spent more time foraging away from their nests; however, nest-guarding smallmouth bass consumed few prey and, in Lake Erie, rarely consumed round gobies. Therefore, increased parental care costs owing to the presence of round gobies could affect future growth, reproduction, and survival if smallmouth bass approach critically low energy reserves.Funding for this project was provided by Federal Aid in Sport Fish Restoration Project F-69-P, administered jointly by United States Fish and Wildlife Service and Ohio Department of Natural Resources, Division of Wildlife, a Sigma Xi Grant-in-Aid awarded to G.B.S., and the Department of Evolution, Ecology, and Organismal Biology at The Ohio State University
Ferroelectric Nanotubes
We report the independent invention of ferroelectric nanotubes from groups in
several countries. Devices have been made with three different materials: lead
zirconate-titanate PbZr1-xTixO3 (PZT); barium titanate BaTiO3; and strontium
bismuth tantalate SrBi2Ta2O9 (SBT). Several different deposition techniques
have been used successfully, including misted CSD (chemical solution
deposition) and pore wetting. Ferroelectric hysteresis and high optical
nonlinearity have been demonstrated. The structures are analyzed via SEM, TEM,
XRD, AFM (piezo-mode), and SHG. Applications to trenching in Si dynamic random
access memories, ink-jet printers, and photonic devices are discussed.
Ferroelectric filled pores as small as 20 nm in diameter have been studied
Polymeric Liquids in Nanoporous Photonic Structures: From Precursor Film Spreading to Imbibition Dynamics at the Nanoscale
Polymers are known to wet nanopores with high surface energy through an
atomically thin precursor film followed by slower capillary filling. We present
here light interference spectroscopy using a nanoporous membrane-based chip
that allows us to observe the dynamics of these phenomena in situ with
sub-nanometer spatial and milli- to microsecond temporal resolution. The device
consists of a mesoporous silicon film (average pore size 6 nm) with an
integrated photonic crystal, which permits to simultaneously measure the phase
shift of the thin-film interference and the resonance of the photonic crystal
upon imbibition. For a styrene dimer, we find a flat fluid front without a
precursor film, while the pentamer forms an expanding molecular thin film
moving in front of the menisci of the capillary filling. These different
behaviors are attributed to a significantly faster pore-surface diffusion
compared to the imbibition dynamics for the pentamer and vice versa for the
dimer. In addition, both oligomers exhibit anomalously slow imbibition
dynamics, which could be explained by apparent viscosities of six and eleven
times the bulk value, respectively. However, a more consistent description of
the dynamics is achieved by a constriction model that emphasizes the increasing
importance of local undulations in the pore radius with the molecular size and
includes a sub-nanometer hydrodynamic dead, immobile zone at the pore wall, but
otherwise uses bulk fluid parameters. Overall, our study illustrates that
interferometric, opto-fluidic experiments with nanoporous media allow for a
remarkably detailed exploration of the nano-rheology of polymeric liquids.Comment: 9 pages, 5 figure
The LISA PathFinder DMU and Radiation Monitor
The LISA PathFinder DMU (Data Management Unit) flight model was formally
accepted by ESA and ASD on 11 February 2010, after all hardware and software
tests had been successfully completed. The diagnostics items are scheduled to
be delivered by the end of 2010. In this paper we review the requirements and
performance of this instrumentation, specially focusing on the Radiation
Monitor and the DMU, as well as the status of their programmed use during
mission operations, on which work is ongoing at the time of writing.Comment: 11 pages, 7 figures, prepared for the Proceedings of the 8th
International LISA Symposium, Classical and Quantum Gravit
Influence of organic diet on the amount of conjugated linoleic acids in breast milk of lactating women in the Netherlands
The aim of the present study was to find out whether the incorporation of organic dairy and meat products in the maternal diet affects the contents of the conjugated linoleic acid isomers (CLA) and trans-vaccenic acid (TVA) in human breast milk. To this purpose, milk samples from 312 breastfeeding mothers participating in the KOALA Birth Cohort Study have been analysed. The participants had documented varying lifestyles in relation to the use of conventional or organic products. Breast milk samples were collected 1month postpartum and analysed for fatty acid composition. The content of rumenic acid (the main CLA) increased in a statistically significant way while going from a conventional diet (no organic dairy/meat products, 0·25 weight % (wt%), n 186) to a moderately organic diet (50-90% organic dairy/meat, 0·29wt%, n 33, P=0·02) and to a strict organic diet (>90% organic dairy/meat, 0·34wt%, n 37, P≤0·001). The levels of TVA were augmented among the participants with a moderately organic diet (0·54wt%) and those with a strict organic diet (0·59wt%, P≤0·001), in comparison with the conventional group (0·48wt%). After adjusting for covariables (recruitment group, maternal age, maternal education, use of supplements and season), statistical significance was retained in the group of the strict organic dairy users (P<0·001 for rumenic acid). Hence, the levels of CLA and TVA in human milk can be modulated if breastfeeding mothers replace conventional dairy and/or meat products by organic ones. A potential contribution of CLA and TVA to health improvement is briefly discusse
Mice with an induced mutation in collagen 8A2 develop larger eyes and are resistant to retinal ganglion cell damage in an experimental glaucoma model
PURPOSE: To study susceptibility to glaucoma injury as it may be affected by mutations in ocular connective tissue components. METHODS: Mice homozygous for an N-ethyl-N-nitrosourea induced G257D exchange (Gly to Asp) missense mutation (Aca23) in their collagen 8A2 gene were studied to measure intraocular pressure (IOP), axial length and width, number of retinal ganglion cells (RGC), and inflation responses. Three month old homozygous Aca23 mutant and wild type (WT) mice had 6 weeks exposure to elevated IOP induced by polystyrene microbead injection. Additional Aca23 and matched controls were studied at ages of 10 and 18 months. RESULTS: Aca23 mice had no significant difference from WT in IOP level, and in both strains IOP rose with age. In multivariable models, axial length and width were significantly larger in Aca23 than WT, became larger with age, and were larger after exposure to glaucoma (n=227 mice). From inflation test data, the estimates of scleral stress resultants in Aca23 mice were similar to age-matched and younger WT C57BL/6 (B6) mice, while the strain estimates for Aca23 were significantly less than those for either WT group in the mid-sclera and in some of the more anterior scleral measures (p<0.001; n=29, 22, 20 eyes in Aca23, older WT, younger WT, respectively). With chronic IOP elevation, Aca23 eyes increased 9% in length and 7% in width, compared to untreated fellow eyes (p<0.05, <0.01). With similar elevated IOP exposure, WT eyes enlarged proportionately twice as much as Aca23, increasing in length by 18% and in nasal-temporal width by 13% (both p<0.001, Mann-Whitney test). In 4 month old control optic nerves, mean RGC axon number was not different in Aca23 and WT (46,905±7,592, 43,628±11,162, respectively; p=0.43, Mann-Whitney test, n=37 and 29). With chronic glaucoma, Aca23 mice had a mean axon loss of only 0.57±17%, while WT mice lost 21±31% (median loss: 1% versus 10%, n=37, 29, respectively; p=0.001; multivariable model adjusting for positive integral IOP exposure). CONCLUSIONS: The Aca23 mutation in collagen 8α2 is the first gene defect found to alter susceptibility to experimental glaucoma, reducing RGC loss possibly due to differences in mechanical behavior of the sclera. Detailed study of the specific changes in scleral connective tissue composition and responses to chronic IOP elevation in this strain could produce new therapeutic targets for RGC neuroprotection
Awe and Wonder in Scientific Practice: Implications for the Relationship Between Science and Religion
This paper examines the role of awe and wonder in scientific practice.
Drawing on evidence from psychological research and the writings of scientists and science communicators, I argue that awe and wonder play a crucial role in scientific discovery. They focus our attention on the natural world, encourage open-mindedness, diminish the self (particularly feelings of self-importance), help to accord value to the objects that are being studied, and provide a mode of understanding in the absence of full knowledge. I will flesh out implications of the role of awe and wonder in scientific discovery for debates on the relationship between science and religion. Abraham Heschel argued that awe and wonder are religious emotions because they reduce our feelings of self-importance, and thereby help to cultivate the proper reverent attitude towards God. Yet metaphysical naturalists such as Richard Dawkins insist that awe and wonder need not lead to any theistic commitments for scientists. The awe some scientists experience can be regarded as a form of non-theistic spirituality, which is neither a reductive naturalism nor theism. I will attempt to resolve the tension between these views by identifying some common ground
Library Cultures of Data Curation: Adventures in Astronomy
University libraries are partnering with disciplinary data producers to provide long-term digital curation of research datasets. Managing dataset producer expectations and guiding future development of library services requires understanding the decisions libraries make about curatorial activities, why they make these decisions, and the effects on future data reuse. We present a study, comprising interviews (n=43) and ethnographic observation, of two university libraries who partnered with the Sloan Digital Sky Survey (SDSS) collaboration to curate a significant astronomy dataset. The two libraries made different choices of the materials to curate and associated services, which resulted in different reuse possibilities. Each of the libraries offered partial solutions to the SDSS leaders’ objectives. The libraries’ approaches to curation diverged due to contextual factors, notably the extant infrastructure at their disposal (including technical infrastructure, staff expertise, values and internal culture, and organizational structure). The Data Transfer Process case offers lessons in understanding how libraries choose curation paths and how these choices influence possibilities for data reuse. Outcomes may not match data producers’ initial expectations but may create opportunities for reusing data in unexpected and beneficial ways
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Ulcerative colitis-risk loci on chromosomes 1p36 and 12q15 found by genome-wide association study.
Ulcerative colitis is a chronic inflammatory disease of the colon that presents as diarrhea and gastrointestinal bleeding. We performed a genome-wide association study using DNA samples from 1,052 individuals with ulcerative colitis and preexisting data from 2,571 controls, all of European ancestry. In an analysis that controlled for gender and population structure, ulcerative colitis loci attaining genome-wide significance and subsequent replication in two independent populations were identified on chromosomes 1p36 (rs6426833, combined P = 5.1 x 10(-13), combined odds ratio OR = 0.73) and 12q15 (rs1558744, combined P = 2.5 x 10(-12), combined OR = 1.35). In addition, combined genome-wide significant evidence for association was found in a region spanning BTNL2 to HLA-DQB1 on chromosome 6p21 (rs2395185, combined P = 1.0 x 10(-16), combined OR = 0.66) and at the IL23R locus on chromosome 1p31 (rs11209026, combined P = 1.3 x 10(-8), combined OR = 0.56; rs10889677, combined P = 1.3 x 10(-8), combined OR = 1.29)
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